KR20230043818A - Method for inter prediction and apparatus thereof - Google Patents

Abstract

An image decoding apparatus according to the present invention includes: a motion estimation part for deriving motion information of a current block as motion information including L0 motion information and L1 motion information; a motion compensation part for generating a prediction block by performing motion compensation on the current block based on at least one of the L0 motion information and the L1 motion information; and a restoration block generation part for generating a restoration block corresponding to the current block based on the prediction block. According to the present invention, the efficiency of encoding the image can be improved.

Description

Inter prediction method and its device {METHOD FOR INTER PREDICTION AND APPARATUS THEREOF}

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

Recently, as broadcasting services with high definition (HD) resolution are expanded not only domestically but also globally, many users are getting used to high-resolution and high-definition images, and many organizations are accelerating the development of next-generation video equipment. In addition, as interest in UHD (Ultra High Definition) having a resolution four times higher than that of HDTV increases along with HDTV, a compression technology for a higher resolution and higher quality image is required.

For image compression, inter prediction technology predicts pixel values included in the current picture from temporally previous and/or subsequent pictures, and predicts pixel values included in the current picture using pixel information in the current picture. An intra prediction technique, an entropy coding technique in which short codes are assigned to symbols with a high frequency of occurrence and long codes are assigned to symbols with a low frequency of occurrence may be used.

A technical problem 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 a video decoding method and apparatus capable of improving video encoding efficiency.

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

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

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

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

The L0 motion information includes an L0 motion vector and an L0 reference picture number, the L0 reference picture number indicates a Picture Order Count (POC) allocated to the L0 reference picture, and the L1 motion information includes an L1 motion vector and an L1 reference picture. It includes a picture number, and the L1 reference picture number may indicate a Picture Order Count (POC) allocated 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 determines, based on the L0 motion information among the L0 motion information and the L1 motion information, You can perform uni prediction.

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

Another embodiment of the present invention is a video decoding device. The apparatus may include a motion prediction unit for deriving motion information of a current block as motion information including L0 motion information and L1 motion information, and motion for the current block based on at least one of the L0 motion information and the L1 motion information. By performing compensation, a motion compensation unit for generating a prediction block corresponding to the current block and a restoration block generation unit for generating a restoration block corresponding to the current block based on the prediction block, wherein the motion compensation unit comprises: 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 a video decoding device. The apparatus includes a motion estimation unit for deriving motion information from an already reconstructed picture, a motion compensation unit for generating a prediction block corresponding to a current block based on the derived motion information, and a motion compensation unit for generating the current block based on the prediction block. A reconstruction block generation unit for generating a corresponding reconstruction block, wherein the motion information includes a motion vector and a reference picture index, and the motion estimation unit sets the reference picture index to 0, and the image The motion vector is derived based on a col block corresponding to the current block in the reconstructed picture.

The coding mode of the current block is a merge mode, and the motion compensation unit selects the temporal motion information as motion information of the current block and performs motion compensation based on the selected motion information, thereby performing motion compensation on the current block. A prediction block corresponding to can be generated.

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

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

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

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

According to the temporal motion information derivation method according to the present invention, video encoding efficiency can 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 a video decoding apparatus to which the present invention is applied.
3 is a flowchart schematically illustrating an embodiment of an inter prediction method.
4 is a diagram schematically illustrating an embodiment of an inter prediction method when bi-prediction is applied.
5 is a diagram schematically illustrating an embodiment of motion information of an encoded image.
6 is a flowchart schematically illustrating an embodiment of a method of deriving temporal motion information of a current block according to the present invention.
7 is a diagram schematically illustrating an embodiment of a reconstructed neighboring block used for resetting L1 temporal motion information.
FIG. 8 is a block diagram schematically illustrating an embodiment of an inter-prediction apparatus capable of deriving temporal motion information according to the embodiment of FIG. 6 .
9 is a flowchart schematically illustrating another embodiment of a method for deriving temporal motion information of a current block according to the present invention.
10 is a diagram schematically illustrating an embodiment of a second collocated block used for resetting L1 temporal motion information.
11 is a block diagram schematically illustrating an embodiment of an inter-prediction apparatus capable of deriving temporal motion information according to the embodiment of FIG. 9 .
12 is a diagram schematically illustrating an embodiment of a method of deriving motion information of a current block according to the present invention.
FIG. 13 is a block diagram schematically illustrating an embodiment of an inter-prediction apparatus capable of deriving motion information according to the embodiment of FIG. 12 .
14 is a flowchart schematically illustrating another embodiment of a method for deriving temporal motion information of a current block according to the present invention.
FIG. 15 is a block diagram schematically illustrating an embodiment of an inter-prediction device capable of deriving temporal motion information according to the embodiment of FIG. 14 .

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely with reference to drawings. In describing the embodiments of the present specification, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

It is understood that when a component is referred to as “connected” or “connected” to another component, it may be directly connected or connected to the other component, but other components may exist in the middle. It should be. In addition, the description of "including" a specific configuration in the present invention does not exclude configurations other than the corresponding configuration, and means that additional configurations may be included in the practice of the present invention or the scope of 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. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention.

In addition, components appearing in the embodiments of the present invention are shown independently to represent different characteristic functions, and do not mean that each component is made of separate hardware or a single software component unit. That is, each component is listed and included as each component for convenience of explanation, and at least two components of each component can be combined to form a single component, or one component can be divided into a plurality of components to perform a function, and each of these components can be divided into a plurality of components. Integrated embodiments and separated embodiments of components are also included in the scope of the present invention as long as they do not depart from the essence of the present invention.

In addition, some of the components may be optional components for improving performance rather than essential components that perform essential functions in the present invention. The present invention can be implemented by including only components essential to implement the essence of the present invention, excluding components used for performance improvement, and a structure 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 video encoding apparatus 100 includes a motion estimation unit 111, a motion compensation unit 112, an intra prediction unit 120, a switch 115, a subtractor 125, and a transform 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 prediction within a picture, and inter prediction means prediction between pictures. In the case of the intra mode, the switch 115 may be switched to the intra mode, and in the case of the inter mode, the switch 115 may be switched to the inter mode. After generating a prediction block for an input block of an input image, the image encoding apparatus 100 may encode a residual between the input block and the prediction block.

In the case of the intra mode, the intra prediction unit 120 may generate a prediction block by performing spatial prediction using pixel values of previously encoded blocks adjacent to 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 picture stored in the reference picture buffer 190 during the motion estimation process. there is. The motion compensator 112 may generate a prediction block by performing motion compensation using a motion vector.

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

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

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

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

The reconstructed block passes through a filter unit 180, and the filter unit 180 applies at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the reconstructed block or the reconstructed picture. can do. The filter unit 180 may also be called an adaptive in-loop filter. The deblocking filter may remove block distortion and/or blocking artifacts generated at the boundary between blocks. SAO may 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 a reconstructed image with an original image, and may be performed only when high efficiency is applied. A 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 a video decoding apparatus to which the present invention is applied.

* Referring to FIG. 2, the video 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, 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 an intra mode or inter mode, and output a reconstructed image, that is, a reconstructed image. In the intra mode, the switch may be converted to intra, and in the case of the inter mode, the switch may be converted to inter. The image decoding apparatus 200 may generate a reconstructed block, that is, a reconstructed block, by obtaining a residual block from the input bitstream, generating a prediction block, and then adding the residual block and the prediction block.

The entropy decoding unit 210 may generate symbols including symbols in the form of quantized coefficients by entropy decoding the input bitstream according to a probability distribution. 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 with a high probability of occurrence and a large number of bits are allocated to a symbol with a low probability of occurrence to express the symbol, thereby increasing the size of the bit stream for each symbol. can be reduced Therefore, compression performance of image decoding may be improved through the entropy decoding method.

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

In the intra mode, the intra prediction unit 240 may generate a prediction block by performing spatial prediction using pixel values of previously decoded blocks adjacent to the current block. In the case of the inter mode, the motion compensation unit 250 may generate a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference picture buffer 270 .

The residual block and the prediction block are added through the adder 255, and the added block 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 a reconstructed picture. The filter unit 260 may output a reconstructed image, that is, a restored 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 video encoding and decoding. When encoding and decoding an image, the encoding or decoding unit refers to the divided unit when encoding or decoding an image by dividing it, such as a coding unit (CU), a prediction unit (PU), and a transform unit (TU). : Transform Unit), a transform block, and the like. One block may be further divided into smaller sub-blocks. In addition, in this specification, “picture” may be replaced with “frame”, “field” and/or “slice” depending on the context, and such distinction can be easily made by those skilled in the art. There will be. For example, P picture, B picture, and forward B picture described later may be replaced with P slice, B slice, and forward B slice, respectively, depending on the context.

3 is a flowchart schematically illustrating 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 decoder may derive motion information of the current block and then perform inter prediction and/or motion compensation based on the derived motion information. At this time, the encoder and decoder use motion information of a collocated block corresponding to the current block in a reconstructed neighboring block and/or a previously reconstructed collocated picture. By using it, encoding/decoding efficiency can be improved. Here, the reconstructed neighboring block is a block in the current picture that has already been encoded and/or decoded and reconstructed, and may include a block adjacent to the current block and/or a block located at an outer corner of the current block. In addition, the encoder and the decoder may determine a predetermined relative position based on a block located at the same spatial position as the current block in the collocated picture, and the determined predetermined relative position (existing at the same spatial position as the current block) The collocated block may be derived based on the location inside and/or outside the block being called). Here, as an example, a call picture may correspond to one picture among reference pictures included in the reference picture list.

Meanwhile, the motion information derivation method may vary according to the prediction mode of the current block. Prediction modes applied for inter prediction may include advanced motion vector predictor (AMVP), merge, and the like.

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

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

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

The encoder may select a merge candidate capable of providing optimal encoding efficiency as motion information for the current block from among merge candidates included in the merge candidate list. 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 the merge candidates included in the merge candidate list using the transmitted merge index, and may determine the selected merge candidate as motion information of the current block. Therefore, when the merge mode is applied, motion information of the reconstructed neighboring block and/or collocated block may be used as motion information of the current block.

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

Referring back to FIG. 3 , the encoder and decoder may generate a prediction block of the current block by performing motion compensation on the current block based on the derived motion information (S320). Here, the prediction block may refer to 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. Therefore, in the embodiments described below, a prediction block may be referred to as a 'motion compensated block' and/or a 'motion compensated image' depending on the context, and such classification is easy for those skilled in the art. will be able to do

Meanwhile, pictures for which inter prediction is performed may include P pictures and B pictures. A P picture can mean a picture for which unidirectional prediction is performed using one reference picture, and a B picture means a picture for which forward, backward, or bidirectional prediction is performed using one or more, for example, two reference pictures. can do. For example, in a B picture, inter prediction may be performed using one forward reference picture (past picture) and one backward reference picture (future picture). Also, for a B picture, prediction may be performed using two forward reference pictures or prediction may be performed using two backward reference pictures.

Here, reference pictures may be managed by a reference picture list. One reference picture is used in the P picture, and the reference picture can be assigned to reference picture list 0 (L0 or List0). Two reference pictures are used in the B picture, and the two reference pictures can be assigned to reference picture list 0 and 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 backward reference picture may be assigned to reference picture list 1. However, the reference picture allocation method is not limited thereto, and a forward reference picture may be allocated to reference picture list 1, and a backward reference picture may be allocated to reference picture list 0. Hereinafter, the reference picture allocated to reference picture list 0 is referred to as an L0 reference picture, and the reference picture allocated to reference picture list 1 is referred to as an L1 reference picture.

Reference pictures can generally be assigned to a reference picture list in descending order according to reference picture numbers. Here, the reference picture number may refer to a number assigned to each reference picture in the order of POC (Picture Order Count), and the POC order may mean a display order and/or a time order of pictures. For example, two reference pictures having the same reference picture number may correspond to the same reference picture. Reference pictures assigned to the reference picture list may be rearranged by a Reference Picture List Reordering (RPLR) or Memory Management Control Operation (MMCO) command.

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

Bi-prediction can be used as a concept that includes all of forward prediction, backward prediction, and bi-prediction, but in the embodiments described later, for convenience, prediction using two reference pictures (L0 reference picture and L1 reference picture) is referred to as bi-prediction. That is, bi-prediction in embodiments to be described later may mean bi-prediction, and can be understood as a concept including all forward, backward, and bi-directional predictions using two reference pictures (L0 reference picture and L1 reference picture). . In addition, even when bi-prediction is performed, forward prediction or backward prediction may be performed. However, in embodiments described later, for convenience, prediction using only one reference picture is referred to as uni-directional prediction. That is, in the embodiments to be described later, uni-prediction may mean uni-prediction, and should be understood as a concept including prediction using only one reference picture. In addition, information indicating whether uni-prediction (uni-prediction) or bi-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 illustrating an embodiment of an inter prediction method when bi-prediction is applied.

As described above, the encoder and decoder can perform bidirectional prediction as well as unidirectional prediction in inter prediction. When bi-prediction is applied, each block on which prediction is performed may have two reference pictures (an L0 reference picture and an L1 reference picture). Also, at this time, each block on which bi-directional 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 reference picture list 0 and reference picture list 1 and use it for prediction. That is, two reference pictures including an L0 reference picture and an L1 reference picture may be used for bidirectional prediction. Hereinafter, motion information corresponding to an L0 reference picture is referred to as L0 motion information, and motion information corresponding to an L1 reference picture is referred to as L1 motion information. Also, motion compensation using L0 motion information is referred to as L0 motion compensation, and motion compensation using L1 motion information is referred to as L1 motion compensation.

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

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

Hereinafter, motion compensation applied in bi-directional prediction is referred to as bi-directional motion compensation. Correspondingly, motion compensation applied in unidirectional prediction may be referred to as unidirectional motion compensation.

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

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

An encoder and a decoder may use a forward B picture to increase inter prediction efficiency in a low-latency application environment. Here, the forward B picture may mean a B picture for which only forward prediction is performed. When a forward B picture is used, each block on which prediction is performed may have two pieces of motion information (L0 motion information and L1 motion information). In a forward B picture, the L0 reference picture list and the L1 reference picture list can generally be set identically. Hereinafter, in this specification, it is assumed that the L0 reference picture list and the L1 reference picture list are the same when a forward B picture is used.

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

The image shown in FIG. 5 is coded using forward B pictures. Accordingly, each block in an encoded 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 pieces of motion information, a block having the same L0 motion information (eg, reference picture number and motion vector) and L1 motion information (eg, reference picture number and motion vector) is There may be many.

A block having the same L0 motion information (eg, reference picture number, motion vector) and L1 motion information (eg, reference picture number, motion vector) in the forward B picture may be generated due to the temporal motion information derivation method. there is. As described above, temporal motion information may be derived from motion information of a collocated block corresponding to a current block in an already reconstructed collocated picture. For example, when deriving L0 temporal motion information of a current block, an encoder and a decoder may use L0 motion information of a collocated block corresponding to the current block within a collocated picture. However, when L0 motion information does not exist in the collocated block, the encoder and decoder may use L1 motion information of the collocated block as L0 temporal motion information of the current block. Conversely, when deriving the L1 temporal motion information of the current block, the encoder and the decoder may use the L1 motion information of the collocated block corresponding to the current block within the collocated picture. However, when L1 motion information does not exist in the collocated block, the encoder and decoder may use L0 motion information of the collocated block as L1 temporal motion information of the current block. As a result of performing the above process, a phenomenon in which the L0 motion information and the L1 motion information of the current block become the same may occur. Therefore, 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, when the reference picture number and motion vector) and L1 temporal motion information (eg, reference picture number and motion vector) are the same, the motion information of the collocated block corresponding to the current block in the previously reconstructed collocated picture is L0 A case of having only one of motion information and L1 motion information may be included.

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

When motion compensation is performed for a block having the same L0 motion information and L1 motion information, the same process may be repeatedly performed twice in one block. Since this is very inefficient from the point of view of encoding, an inter prediction method and/or a motion compensation method capable of reducing computational complexity and improving encoding efficiency can be provided by solving the above problems. For example, 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, the encoder and decoder perform the motion compensation process only once. The computational complexity can be reduced. As another example, 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, the encoder and decoder use the L0 motion information and/or the L1 motion information. Encoding efficiency may be increased by resetting information.

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

Embodiments to be described later are described based on temporal motion information, but the present invention is not limited thereto. For example, the methods according to the embodiment of FIG. 6 include not only temporal motion information in merge mode and/or AMVP mode, but also motion information of a current block derived based on a merge candidate list in merge mode and/or AMVP mode. The same or similar method can be applied to motion information of the current block derived based on the predicted motion vector candidate list.

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

Referring to FIG. 6, an encoder and a decoder determine whether L0 temporal motion information and L1 temporal motion information are the same in temporal motion information derived based on a collocated block, 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 (S610).

When the L0 temporal motion information and the L1 temporal motion information are not identical, that is, when the L0 reference picture number and the L1 reference picture number are not identical and/or the L0 motion vector and the L1 motion vector are not identical, the encoder and decoder call Temporal motion information derived based on the block may be used as temporal motion information for the current block as it is. When AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate for the current block. Also, 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 a block having motion information exists among reconstructed neighboring blocks at 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 has already been 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 motion information of a reconstructed neighboring block does not exist (for example, when a block having motion information does not exist among reconstructed neighboring blocks at a predetermined position and/or a position selected by a predetermined method), an encoder and a decoder The machine may reset the prediction direction information of the current block to unidirectional prediction (S630). Also, at this time, the encoder and decoder may use only L0 temporal motion information as temporal motion information of the current block.

When motion information of a reconstructed neighboring block exists (for example, when a block having motion information exists among reconstructed neighboring blocks at a predetermined position and/or a position selected by a predetermined method), the encoder and decoder The motion information of the reconstructed neighboring block may be used as the 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 the motion information of the reconstructed neighboring block. A specific embodiment of the reconstructed neighboring block used for setting the L1 temporal motion information will be described later.

In the above-described embodiment, the method 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 in the flowchart may be deleted. For example, in the above-described embodiment, steps S620 and S640 may be omitted. At this time, when the L0 temporal motion information and the L1 temporal motion information are the same, the encoder and the decoder may reset the prediction direction information of the current block to unidirectional prediction (S630). Also, at this time, the encoder and decoder may use only L0 temporal motion information as temporal motion information of the current block.

Meanwhile, in the above-described embodiment, whether or not to perform processes S620 to S640 is determined based on the equality of L0 temporal motion information and L1 temporal motion information, but the encoder and decoder determine whether to perform processes S620 to S640 based on other conditions. may be

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

As another embodiment, the encoder and decoder may determine whether to perform processes S620 to S640 based on the prediction direction of the collocated block. As described above, 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 decoder may perform steps S620 to S640 when the motion information (prediction direction) of the collocated block is unidirectional prediction instead of bidirectional prediction. This is because, when the prediction direction of the collocated block is unidirectional prediction, the L0 temporal motion information and the L1 temporal motion information may be the same in temporal motion information derived based on the collocated block as a result.

As another embodiment, the encoder and decoder may determine whether to perform processes S620 to S640 based on information on whether motion information exists in the collocated block. For example, the encoder and decoder may perform steps S620 to S640 when motion information does not exist in the collocated block. In this case, L0 temporal motion information instead of L1 temporal motion information may be reset in step S640 described above. That is, the encoder and decoder may set L0 temporal motion information as motion information of a reconstructed neighboring block, and perform unidirectional prediction rather than bidirectional prediction on the current block. In addition, when motion information does not exist in the collocated block, the encoder and decoder may reset both the L0 temporal motion information and the L1 temporal motion information in step S640 described above. That is, the encoder and decoder may set the L0 temporal motion information and the L1 temporal motion information as motion information of the reconstructed neighboring block, and may perform bi-directional prediction on the current block.

As another embodiment, the encoder and decoder may determine whether to perform processes S620 to S640 based on the size of the current block. For 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, for example, one of 8x8, 16x16, and 32x32. At this time, the encoder and decoder may perform steps S620 to S640 when the size of the current block is smaller than a predetermined size.

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

The condition for determining whether or not to perform the steps S620 to S640 is not limited to the above-described embodiment, and various conditions may be applied according to conditions and/or needs.

Meanwhile, when AMVP is applied, the encoder and/or decoder may use a candidate having the smallest difference from the motion vector of the current block among the motion vector predictor candidates in the predictor motion vector candidate list as the predictive motion vector of the current block, and merge is applied. In this case, the encoder and/or the decoder may use a merge candidate capable of providing optimal coding 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 reconstructed. 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 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 above-described step of determining whether or not a restored neighboring block exists (S630) may be omitted. Hereinafter, in an embodiment to be described later, a motion information candidate list may be understood as a concept including a predictive 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 decoder may use one of the motion information candidates included in the motion information candidate list of the current block as the L1 temporal motion information. Motion information used as L1 temporal motion information in the motion information candidate list of the current block may be determined in various ways.

As an embodiment, the encoder and decoder may sequentially search motion information candidates in the motion information candidate list from the first motion information candidate to the last motion information candidate. In this case, the encoder and 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 collocated block as the L1 temporal motion information of the current block. In this case, the encoder and decoder may use the L0 motion information of the first motion information candidate having the same reference picture number as the L1 reference picture number, or the first motion information candidate having the same reference picture number as the L1 reference picture number. L1 motion information of may be used. Meanwhile, motion information having the same reference picture number as the L1 reference picture number of the L1 temporal motion information derived based on the collocated 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 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.

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

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

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

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

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

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

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

Meanwhile, the encoder and decoder may not use the motion information and/or the motion information candidate list of the reconstructed neighboring block to reset the L1 temporal motion information (eg, L1 motion vector) of the current block in the above-described step S640. may be At this time, the encoder and decoder may reset 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 motion vectors.

As an embodiment, the encoder and the decoder transmit motion information indicating a relative position moved based on a predetermined distance and/or direction from a position indicated by L0 temporal motion information (L0 motion vector) of the current block to L1 of the current block. It can be used as temporal motion information (L1 motion vector). As an example, the encoder and decoder have a 1/4 pixel size in the vertical and/or horizontal direction (eg, (-1,0), (1,0), ( 0,-1), (0,1), (-1,-1), (-1,1), (1,-1), (1,1) etc. Here, 1/4 pixel unit is 1 corresponds to.) may be used as L1 temporal motion information of the current block. As another example, the encoder and decoder have a 1/2 pixel size in the vertical and/or horizontal direction (eg, (-2,0), (2,0), ( 0,-2), (0,2), (-2,-2), (-2,2), (2,-2), (2,2) etc. Here, 1/4 pixel unit is 1 corresponds to.) may be used as L1 temporal motion information of the current block. As another example, the encoder and decoder have integer pixel sizes (eg, (-4,0), (4,0), (0) in the vertical and/or horizontal directions 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 equals 1 corresponding.) may be used as the L1 temporal motion information of the current block. Meanwhile, since a motion vector includes a vertical component and a horizontal component, the above-described methods (movement by 1/4 pixel size, movement by 1/2 pixel size, and movement by integer pixel size) Each component may be applied independently. In this case, the movement distance in the horizontal direction and the movement distance in the vertical direction may be different from each other.

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

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

Meanwhile, in the above-described embodiment, the temporal motion information input in step S610 before resetting 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 collocated block as described above, and the L0 reference picture index and the L1 reference picture index may be reference pictures spatially derived from the reconstructed neighboring blocks. can be an index. In this case, the L0 reference picture index and the L1 reference picture index may be set to the smallest non-negative value 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 a 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, only for the embodiments of FIGS. 6 to 8 described later, for convenience of description, the temporal motion information input in step S610 before resetting the temporal motion information is referred to as input temporal motion information (L0 input temporal motion information, L1 input temporal motion information). . In addition, the motion vector included in the input temporal motion information is the input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is the 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 numbers, L1 input reference picture numbers).

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 a reset process for the L1 input reference picture index are described.

As 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 may use the motion information of the reconstructed neighboring block as the L1 temporal motion information of the current block. At this time, the encoder and 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.

As 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 the decoder may reset both the L0 input reference picture index and the L1 input reference picture index to a value of 0 and use them as final temporal motion information. This is because when the L0 input temporal motion information and the L1 input temporal motion information are the same, there is a high probability that both the L0 reference picture index and the L1 reference picture index are 0.

As 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 value. For example, 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. In this case, for example, the encoder and 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 to reset 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 to reset the L1 input reference picture index.

Meanwhile, as described above, the encoder and decoder may derive the final L1 temporal motion vector by resetting the L1 input motion vector value in the L1 input temporal motion information to the same value as the motion vector of the reconstructed neighboring block. In this case, 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 final L1 temporal motion information without a resetting process, or may be used as final L1 temporal motion information through a resetting process as in the above-described embodiment. In this case, 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 from each other. In this case, the encoder and decoder may perform scaling on motion vectors of the reconstructed neighboring blocks and use the scaled motion vectors as 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). In the following embodiments, it is assumed that the L1 input motion vector is reset based on the reconstructed neighboring block. That is, it is assumed that the encoder and decoder reset the L1 input motion vector to one value among the motion vectors of the reconstructed neighboring blocks.

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

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

In another embodiment, the encoder and the decoder only select motion vectors whose difference from the L0 temporal motion information (L0 motion vector) of the current block is equal to or less than a predetermined threshold among the motion vectors of the reconstructed neighboring blocks in order to reset 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. In this case, for example, the L1 input reference picture index may be used as the final L1 temporal motion information without a resetting process. As another example, an L1 input reference picture index value may be reset to a reference picture index value of a reconstructed neighboring block, and the reset reference picture index may be used as 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 for each of these have been described above, they will be omitted here.

The combination of the embodiments of the motion vector resetting process and the reference picture index resetting process 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. there is.

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, 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 reset the prediction direction information of the current block to unidirectional prediction. At this time, the encoder and 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 as a combined combination with the above-described embodiments.

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

As described above, a reconstructed neighboring block is a block in a current picture that has already been 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 710 . In the embodiment of FIG. 7 , the block located at the lower left corner outside the current block 710 is referred to as the lower left corner block (A), and the block located at the upper left corner outside the current block 710 is referred to as the upper left corner block (E). ), and the block located at the upper right corner outside the current block 710 is referred to as the upper right corner block (C). In addition, among the blocks adjacent to the left of the current block 710, the uppermost block is the leftmost block (F), and among the blocks adjacent to the left of the current block 710, the lowermost block is the leftmost block (A), and the current block ( 710) Among the blocks adjacent to the top, the leftmost block is referred to as the top leftmost block (G), and the rightmost block among the blocks adjacent to the top of the current block 710 is referred to as the top rightmost block (B).

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

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

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

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

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

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

Inputs for the temporal motion information derivation process may include the position of the top-left sample of the current block (xP, yP), an input motion vector (mvLXCol), and an input reference picture number (RefPicOrder (currPic, refIdxLX, LX)). there is. Here, currPic may mean the current picture. Outputs of the process may be a motion vector (mvLXCol) used as the final temporal motion information and information indicating whether the final temporal motion information exists (availableFlagLXCol). Here, X may have a value of 0 or 1. For example, when X is 0, mvLXCol, refIdxLX, and LX may represent mvL0Col, refIdxL0, and L0, which may mean variables related to L0 temporal motion information. Also, mvLX can represent a motion vector, mvLX[0] can mean a motion vector of an x component, and mvLX[1] can mean a motion vector of a 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. If the refIdxLX value is 0, refIdxLX may indicate the first reference picture in the LX reference picture list, and if the refIdxLX value is -1, refIdxLX may indicate that no reference picture exists in the reference picture list. In addition, predFlagLX, which will be described later, may indicate whether motion compensation is performed when generating a prediction block. For example, when the value of predFlagLX is 1, an encoder and a 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 (ie, the L0 reference picture number and the L1 reference picture number are the same), the encoder and The decryptor may perform the following process.

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

mvL1Col = mvL0A

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

mvL1Col = mvL0B

Otherwise, if there is an upper-left corner block (E(xP-1, yP-1)) located at the upper-left corner outside the current block, the upper-left corner 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 about the leftmost block E.

mvL1Col = mvL0E

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

availableFlagL1Col = 0

Then, the encoder and decoder may perform the following process.

availableFlagCol = availableFlagL0Col || availableFlagL1Col

predFlagLXCol = availableFlagLXCol

Here, availableFlagCol may indicate whether temporal motion information is derived, and predFlagLXCol may indicate whether or not final temporal motion information for each of the L0 temporal motion information and the L1 temporal motion information exists.

FIG. 8 is a block diagram schematically illustrating an embodiment of an inter-prediction apparatus capable 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 restored neighboring block motion information determination unit 820, a prediction direction information resetting 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 determining unit 810 determines whether L0 temporal motion information and L1 temporal motion information are the same in the input temporal motion information, that is, the L0 reference picture number and the L1 reference picture number are identical and the L0 motion vector It may be determined whether the L1 motion vector and L1 are the same.

When the L0 temporal motion information and the L1 temporal motion information are not identical, the inter prediction device may use the input temporal motion information as it is as the temporal motion information of the current block. When AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate for the current block. Also, 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 restored neighboring block motion information determining unit 820 may be performed.

Meanwhile, as described above with reference to FIG. 6 , the temporal motion information determining unit 810 determines whether the L0 temporal motion information and the L1 temporal motion information are identical, but whether the L0 reference picture number and the L1 reference picture number are identical or predicts a collocated block. direction can be determined. For example, when 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 it is 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 restored neighboring block motion information determining unit 820 may be performed. As another example, when the prediction direction of the collocated block is bidirectional prediction, the inter-prediction device may use input temporal motion information as it is as temporal motion information of the current block, and if the prediction direction of the collocated block is unidirectional prediction, the motion of the reconstructed neighboring blocks A judgment 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 motion information of a reconstructed neighboring block does not exist (for example, when a block having motion information does not exist among reconstructed neighboring blocks at a predetermined position and/or a position selected by a predetermined method), prediction direction information A process of resetting prediction direction information and setting L0 motion information by the resetting and L0 motion information setting unit 830 may be performed. In addition, when motion information of a reconstructed neighboring block exists (for example, when a block having motion information among reconstructed neighboring blocks at a predetermined position and/or a position selected by a predetermined method exists), L1 temporal motion A resetting process by the information resetting unit 840 may be performed.

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

When motion information of the reconstructed neighboring block exists, the L1 temporal motion information resetter 840 may reset the L1 temporal motion information of the current block to the motion information of the restored neighboring block. That is, the inter-prediction apparatus may use the motion information of the reconstructed neighboring block as the L1 temporal motion information of the current block. At this time, for example, when the L1 temporal motion information resetter 840 searches for motion information to be used as the L1 temporal motion information of the current block in the restored neighboring blocks, it does not select the motion information having the zero vector (0,0). It is also possible to select only motion information that does not have zero vectors (0,0). Meanwhile, the L1 temporal motion information resetter 840 may reset the L1 temporal motion information of the current block based on the motion information candidate list of the current block. Since specific embodiments of each of the above-described methods have been described above with reference to FIGS. 6 and 7, they will be omitted herein.

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

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

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

Referring to FIG. 9, an encoder and a decoder determine whether L0 temporal motion information and L1 temporal motion information are the same in temporal motion information derived based on a collocated block, 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 (S910). Hereinafter, only for the embodiments of FIGS. 9 to 11 described later, for convenience of description, the temporal motion information input in step S910 before resetting the 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 the input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is the 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 numbers, L1 input reference picture numbers).

When the L0 input temporal motion information and the L1 input temporal motion information are not identical, that is, when the L0 input reference picture number and the L1 input reference picture number are not identical and/or the L0 input motion vector and the L1 input motion vector are not identical , the encoder and decoder can use the input temporal motion information derived based on the collocated block as the temporal motion information of the current block. When AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate of the current block. Also, when 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 motion information of the collocated block exists (S920). Here, the collocated block may be a newly derived collocated block other than a collocated block used for deriving input temporal motion information. For example, the encoder and decoder may determine whether a block having motion information exists among collocated blocks at a predetermined position and/or a position selected by a predetermined method.

Hereinafter, only for the embodiments of FIGS. 9 to 11, for convenience of description, the collocated block used for deriving input temporal motion information is referred to as a first collocated block, and as in step S920, it is subject to determination of whether motion information exists and will be described later. As in step S940, the collocated block used for resetting the L1 input temporal motion information is referred to as the second collocated block. Also, a collocated picture including a first collocated block is referred to as a first collocated picture, and a collocated picture including a second collocated block is referred to as a second collocated picture. Here, as an example, each of the first collocated picture and the second collocated picture may correspond to one picture among reference pictures included in the reference picture list.

When motion information of the second collocated block does not exist (for example, when a block having motion information does not exist among the second collocated blocks at a predetermined position and/or a position selected by a predetermined method), an encoder and a decoder The machine may reset the prediction direction information of the current block to unidirectional prediction (S930). Also, at this time, the encoder and decoder may use only L0 input temporal motion information as temporal motion information of the current block.

When motion information of the second collocated block exists (for example, when a block having motion information exists among the second collocated blocks at a predetermined position and/or a position selected by a predetermined method), the encoder and decoder Motion information of the second collocated block may be used as 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 the motion information of the second collocated block. A specific embodiment of the second collocated picture and the second collocated 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 in 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 reset the prediction direction information of the current block to unidirectional prediction (S930). Also, at this time, the encoder and decoder may use only L0 input temporal motion information as final temporal motion information of the current block.

Meanwhile, in the above-described embodiment, whether or not to perform steps S920 to S940 is determined based on the equality of L0 input temporal motion information and L1 input temporal motion information, but the encoder and decoder determine whether to perform steps S920 to S940 based on other conditions. can also decide

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

As another embodiment, the encoder and decoder may determine whether to perform processes S920 to S940 based on the prediction direction of the first collocated block. As described above, 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 decoder may perform steps S920 to S940 when the motion information (prediction direction) of the first collocated block is unidirectional prediction instead of bidirectional prediction. This is because when the prediction direction of the first collocated block is unidirectional prediction, the L0 input temporal motion information and the L1 input temporal motion information may be the same in input temporal motion information derived from the first collocated block as a result.

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

As another embodiment, the encoder and decoder may determine whether to perform processes S920 to S940 based on the size of the current block. For 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, for example, one of 8x8, 16x16, and 32x32. At this time, the encoder and decoder may perform steps S920 to S940 when the size of the current block is smaller than a predetermined size.

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

The condition for determining whether to perform the steps S920 to S940 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, since the L0 input temporal motion information and the L1 input temporal motion information are temporally derived motion information, they are highly likely to correspond to motion information caused by movement of an object. Therefore, when the encoder and decoder search motion information to be used as the final L1 temporal motion information of the current block in the second collocated block, motion information having zero vector (0,0) is not selected and zero vector (0,0) Motion information that does not have may be selected. This is because a block having motion information corresponding to the zero vector (0,0) is highly likely to correspond to a background rather 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 final L1 temporal motion information of the current block in the second collocated block. For example, as in S940, when the final L1 temporal motion information of the current block is derived based on the second collocated block, the encoder and decoder recall blocks having motion information different from the L0 input temporal motion information of the current block. It may be determined as a block used for deriving final L1 temporal motion information. In this case, the encoder and decoder may select only motion information having a difference of less than a predetermined threshold with the L0 input temporal motion information of the current block as the motion information to be used as the final L1 temporal motion information. Here, the predetermined threshold may be determined based on mode information of the current block, motion information of the current block, mode information of neighboring blocks, and/or motion information of neighboring blocks, and the like, and may be determined in various ways.

*In addition, in the above-described embodiments, the motion information of the second collocated block may include both L0 motion information and L1 motion information. 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 final L1 temporal motion information of the current block. For example, the encoder and decoder may use L0 motion information of the second collocated block as final L1 temporal motion information for the current block. At this time, when L0 motion information does not exist in the second collocated block, the encoder and decoder may use the L1 motion information of the second collocated block as final L1 temporal motion information for the current block. As another example, the encoder and decoder may use the L1 motion information of the second collocated block as final L1 temporal motion information for the current block. At this time, when L1 motion information does not exist in the second collocated block, the encoder and decoder may use the L0 motion information of the second collocated block as final L1 temporal motion information for the current block.

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

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

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

The method of resetting 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 collocated 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 can be applied in the same or similar manner to the case of resetting the L1 input temporal motion information based on the motion information of the second collocated 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 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 temporally derived based on the first collocated block as described above, and the L0 input reference picture index and the L1 input reference picture index are obtained from the reconstructed neighboring blocks. It may be a spatially derived reference picture index. In this case, the L0 input reference picture index and the L1 input reference picture index may be set to the smallest non-negative value among the reference picture indices 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 a reconstructed neighboring block.

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

As an embodiment, the encoder and decoder may reset the L1 input reference picture index based on the second collocated block. As described above, the encoder and decoder may use motion information of the second collocated block as final L1 temporal motion information of the current block. At this time, the encoder and 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 collocated 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.

As 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 the decoder may reset both the L0 input reference picture index and the L1 input reference picture index to a value of 0 and use them as final temporal motion information. This is because when the L0 input temporal motion information and the L1 input temporal motion information are the same, there is a high probability that both the L0 reference picture index and the L1 reference picture index are 0.

As 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 value. 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. In this case, for example, the encoder and 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 to reset 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 to reset the L1 input reference picture index.

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

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

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

In another embodiment, the encoder and the decoder may use the first collocated picture used to derive the L0 input temporal motion information as a second collocated picture as it is, as in the above-described embodiment, and the second collocated block is the second collocated picture can be derived from At this time, the encoder and the decoder derive a motion vector having a difference between the L0 input motion vector and the L0 input motion vector equal to or less than a predetermined threshold among the motion vectors of the second collocated block in order to reset the L1 input motion vector. can do. The encoder and decoder may perform scaling on the derived motion vector, and the scaled motion vector may be used as final L1 temporal motion information. In this case, for example, the L1 input reference picture index may be used as the final L1 temporal motion information without a resetting process. That is, the encoder and the decoder can directly allocate the L1 input reference picture index 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 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.

As another embodiment, the encoder and decoder may use a reference picture that is not the same as the first collocated picture used for deriving the L0 input temporal motion information as the second collocated picture. Here, the second collocated picture may be, for example, a most recently decoded reference picture among reference pictures in the L1 reference picture list that is not the same as the first collocated picture. As another example, the encoder and decoder may select a reference picture most frequently used as the second collocate picture based on reference picture indices of the reconstructed neighboring blocks. The second collocated block may be derived from the second collocated picture, and in this case, the encoder and decoder may scale and use the motion vector of the second collocated block to reset the L1 input motion vector. In this case, the scaled motion vector may be used as final L1 temporal motion information. In this case, for example, the L1 input reference picture index may be used as the final L1 temporal motion information without a resetting process. That is, the encoder and the decoder can directly allocate the L1 input reference picture index 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 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.

As another embodiment, the encoder and decoder may use a reference picture that is not the same as the first collocated picture used for deriving L0 input temporal motion information as the second collocated picture, as in the above-described embodiment, and the second collocated block. may be derived from the second call picture. Here, the second collocated picture may be, for example, a most recently decoded reference picture among reference pictures in the L1 reference picture list that is not the same as the first collocated picture. As another example, the encoder and decoder may select a reference picture most frequently used as the second collocate picture based on reference picture indices of the reconstructed neighboring blocks. At this time, the encoder and the decoder derive a motion vector having a difference between the L0 input motion vector and the L0 input motion vector equal to or less than a predetermined threshold among the motion vectors of the second collocated block in order to reset the L1 input motion vector. can do. The encoder and decoder may perform scaling on the derived motion vector, and the scaled motion vector may be used as final L1 temporal motion information. In this case, for example, the L1 input reference picture index may be used as the final L1 temporal motion information without a resetting process. That is, the encoder and the decoder can directly allocate the L1 input reference picture index 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 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 motion vector resetting process and the reference picture index resetting process 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. there is.

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

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

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

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

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

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

In the above-described embodiments, the encoder and decoder may determine only a reference picture that is not the same as the first collocated picture used for deriving the L0 input temporal motion information as the second collocated picture. In this case, only a reference picture that is not identical to the first collocated picture may be used to derive 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 according to implementation and/or needs.

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

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

In one embodiment, the encoder and the decoder derive motion information used as the final L1 temporal motion information from one block existing at a predetermined position with respect to the co-located block among blocks located inside and/or outside the co-located block. can do. At this time, one block existing at the predetermined location may correspond to the second collocated block. Here, the blocks at the predetermined positions are 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, and 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 located at a predetermined position among blocks located inside and/or outside the block at the same position in a predetermined order. In this case, the encoder and decoder may use motion information of a first block having motion information in the 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 collocated block. A 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.

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

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

11 is a block diagram schematically illustrating an embodiment of an inter-prediction apparatus capable 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 determining unit 1110, a second collocated block motion information determining unit 1120, a prediction direction resetting 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 or not L0 input temporal motion information and L1 input temporal motion information are the same in the input temporal motion information, that is, the L0 input reference picture number and the L1 input reference picture number are the same. and determine whether the L0 input motion vector and the L1 input motion vector are the same.

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

On the other hand, as described above with reference to FIG. 9 , the temporal motion information determining unit 1110 determines whether the L0 input temporal motion information and the L1 input temporal motion information are identical, not whether the L0 input reference picture number and the L1 input reference picture number are identical or not. The prediction direction of the first collocated 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 it is as the temporal motion information of the current block, and the L0 input reference picture number and the L1 input reference picture number When the reference picture numbers are the same, a decision process by the second collocated block motion information determiner 1120 may be performed. As another example, when the prediction direction of the first collocated block is bidirectional prediction, the inter-prediction device may use the input temporal motion information as it is as the temporal motion information of the current block, and if the prediction direction of the first collocated block is unidirectional prediction, the inter-prediction device may use the input temporal motion information as it is. 2 A decision process by the collocated block motion information determining unit 1120 may be performed.

The second collocated block motion information determining unit 1120 may determine whether motion information of the second collocated block exists. When motion information of the second collocated block does not exist (for example, when a block having motion information does not exist among the second collocated blocks at a predetermined position and/or a position selected by a predetermined method), prediction direction information A process of resetting prediction direction information and setting L0 motion information by the resetting and L0 motion information setting unit 1130 may be performed. In addition, when motion information of the second collocated block exists (for example, when a block having motion information exists among the second collocated blocks at a predetermined position and/or a position selected by a predetermined method), L1 temporal motion A resetting process by the information resetting unit 1140 may be performed.

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

When there is motion information of the second collocated block, the L1 temporal motion information resetter 1140 may reset the L1 input temporal motion information of the current block to the motion information of the second collocated block. That is, the inter-prediction apparatus may use motion information of the second collocated block as final L1 temporal motion information of the current block. At this time, when the motion information of the second collocated block includes the zero vector (0,0), the L1 temporal motion information resetter 1140 converts the motion information of blocks located around the second collocated block to the final block of the current block. It can also be used as L1 temporal motion information. Since specific embodiments of each of the above-described methods have been described above with reference to FIGS. 6 and 7, they will be omitted herein.

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

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

Meanwhile, in the video decoding process, an undecoded picture among previous pictures of the current picture (and/or the picture to be decoded) may exist due to excessive network traffic. In this case, an incorrect collocated block may be used in a 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. Therefore, in order to solve the above problem, in deriving the motion information of the current block, the encoder and the decoder spatially derive one of the L0 motion information and the L1 motion information based on the reconstructed neighboring block, and the other one derives the collocated block. can be derived temporally. That is, the encoder and decoder can independently set the L0 motion information and the L1 motion information. In this case, even when there is a previous picture that has not been decoded, the encoder and the decoder can restore the current picture to some extent.

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

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

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

Meanwhile, in the above-described embodiment, the encoder and decoder may derive L1 motion information based on L0 motion information. As an example, it is assumed that the L0 motion information is motion information derived based on a collocated block. In this case, as described above, the encoder and decoder may use spatial motion information spatially derived based on the reconstructed neighboring block as L1 motion information. In this case, for example, the encoder and the decoder may derive only motion information identical to 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 decoder may derive only motion information that is not identical to L0 motion information as spatial motion information to be used as L1 motion information. In this case, the encoder and the decoder may derive only motion information having a difference from the L0 motion information equal to or less than a predetermined threshold as spatial motion information to be used as the L1 motion information. Here, the predetermined threshold may be determined based on mode information of the current block, motion information of the current block, mode information of neighboring blocks, and/or motion information of neighboring blocks, and the like, and may be determined in various ways.

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

Meanwhile, when the L0 motion information and/or the L1 motion information are spatially derived based on the motion information of the reconstructed neighboring block, the motion information of the reconstructed neighboring block is spatially derived spatial motion information and temporally derived temporal motion. All information may be included. In this case, the encoder and decoder may derive L0 motion information and/or L1 motion information of the current block using only the spatial motion information derived spatially from among the motion information of the reconstructed neighboring blocks.

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

Meanwhile, in the derived motion information of the current block, L0 motion information and L1 motion information 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 reset the prediction direction information of the current block to unidirectional prediction. At this time, the encoder and decoder may use only L0 motion information as motion information of the current block.

FIG. 13 is a block diagram schematically illustrating an embodiment of an inter-prediction apparatus capable 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 integrating unit 1330.

As described above in the embodiment of FIG. 12, the encoder and decoder can independently set L0 motion information and L1 motion information. In this case, the encoder and the decoder may spatially derive one of the L0 motion information and the L1 motion information based on the reconstructed neighboring block and temporally derive the other one based on the collocated 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 motion information (spatial motion information) derived spatially based on the reconstructed neighboring blocks as L0 motion information, or motion information temporally derived based on the collocated block (temporal motion information). can be used as L0 motion information. That is, the L0 motion information may be spatially derived based on a reconstructed neighboring block or temporally derived based on a collocated block.

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

Since a specific embodiment of the method of setting the L0 motion information and the L1 motion information has been described in detail with reference to 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 integrating the motion of the current block. information can be derived.

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

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

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

Referring to FIG. 14, an encoder and a decoder determine whether L0 temporal motion information and L1 temporal motion information are the same in temporal motion information derived based on a collocated block, that is, if 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, only for the embodiments of FIGS. 14 and 15 to be described later, for convenience of description, the temporal motion information input in step S1410 before resetting the temporal motion information is input temporal motion information (L0 input temporal motion information, L1 input temporal motion information). do. In this case, the input temporal motion information may correspond to temporal motion information derived based on the collocated block. In addition, the motion vector included in the input temporal motion information is the input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is the 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 numbers, L1 input reference picture numbers). Also, in an embodiment described later, a reference picture indicated by an L0 input reference picture index is referred to as an L0 reference picture, and a reference picture indicated by an L1 input reference picture index is referred to as an L1 reference picture.

When the L0 temporal motion information and the L1 temporal motion information are not identical, that is, when the L0 reference picture number and the L1 reference picture number are not identical and/or the L0 motion vector and the L1 input motion vector are not identical, the encoder and decoder Input temporal motion information derived based on the collocated block may be used as final temporal motion information of the current block as it is. When AMVP is applied, the final temporal motion information may be determined or registered as a predictive motion vector candidate of the current block. Also, 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 L0 input temporal motion information and 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 an embodiment to be described later, the L1 reference picture may mean the same picture as the L0 reference picture.

For example, the encoder and the decoder may search for and derive motion information from the L1 reference picture in the same way. In this case, 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, include the derived motion information in a bitstream, and transmit the motion information 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 by the encoder may include a reference picture index and motion vector, and the encoder may independently transmit the reference picture index and motion vector to the 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 back to FIG. 14 , 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 motion information value derived from the L1 reference picture.

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

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

As another example, the encoder may derive a region that best matches or is similar to an input block (original block) corresponding to the current block in the L1 reference picture. In this case, the encoder may derive motion information to be used as final L1 temporal motion information of the current block based on the derived region. For example, the encoder may derive a motion vector to be used as the final L1 temporal motion information based on the position of the block corresponding to the derived region and the position of the current block, and based on the block corresponding to the derived region, the final 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 the L1 input reference picture number). In this case, the encoder and decoder may use the reference picture index (and/or reference picture index) derived from the L1 reference picture as final L1 temporal motion information of the current block.

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

On the other hand, in the above-described embodiment, whether or not to perform the steps S1420 to S1430 is determined based on the sameness of the L0 input temporal motion information and the L1 input temporal motion information, but the encoder and the decoder determine whether to perform the steps S1420 to S1430 based on other conditions. can also decide

As an embodiment, the encoder and decoder may determine whether to perform processes S1420 to S1430 based on the prediction direction of the collocated block. As described above, 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 decoder may perform steps S1420 to S1430 when the motion information (prediction direction) of the collocated block is unidirectional prediction instead of bidirectional prediction. This is because when the prediction direction of the first collocated block is unidirectional prediction, the L0 input temporal motion information and the L1 input temporal motion information may be the same in input temporal motion information derived from the first collocated block as a result.

As another embodiment, the encoder and decoder may determine whether or not to perform processes S1420 to S1430 based on information on whether motion information exists in the collocated block. For example, the encoder and decoder may perform steps S1420 to S1430 when motion information does not exist in the collocated block. In this case, in step S1430 described above, L0 input temporal motion information instead of L1 input temporal motion information may be reset. That is, the encoder and decoder may reset the L0 input temporal motion information to the motion information of the L1 reference picture, and perform unidirectional prediction rather than bidirectional prediction on the current block. In addition, when motion information does not exist in the collocated block, the encoder and decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information in step S1430 described above. That is, the encoder and decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information to the motion information of the L1 reference picture, and may perform bi-directional prediction on the current block.

As another embodiment, the encoder and decoder may perform steps S1420 to S1430 when the L0 motion vector and/or the L1 motion vector in the motion information of the collocated block correspond to the zero vector (0,0). In this case, in step S1430 described above, the encoder and decoder may reset the motion vector(s) corresponding to the zero vector (0,0). For example, the motion vector(s) corresponding to the zero vector (0,0) may be set as a motion vector of the L1 reference picture, and as another example, the motion vector(s) corresponding to the zero vector (0,0) ) may be set as a motion vector of a reconstructed neighboring block, and as another example, the motion vector(s) corresponding to the zero vector (0,0) may be set as a motion vector of a block located around the collocated block. there is. As another embodiment, the encoder and decoder may perform steps S1420 to S1430 when the L0 motion vector and/or the L1 motion vector in the motion information of the collocated block does not correspond to the zero vector (0,0). In this case, in step S1430 described above, the encoder and decoder may reset the motion vector(s) that do not correspond to the zero vector (0,0), and the motion vector(s) that does not correspond to the zero vector (0,0). ) may be reset to the motion vector of the L1 reference picture.

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

Meanwhile, motion information derived from the L1 reference picture may be the same as L0 input temporal motion information of the current block. Accordingly, when the encoder and the decoder search for motion information to be used as the final L1 temporal motion information of the current block in the L1 reference picture, they may find only motion information that is not identical to the L0 input temporal motion information. For example, as in S1430, when the final L1 temporal motion information of the current block is derived based on the L1 reference picture, the encoder and decoder only use motion information different from the L0 input temporal motion information of the current block as the final L1 temporal motion information. can be used as In this case, the encoder and decoder may select only motion information having a difference of less than a predetermined threshold with the L0 input temporal motion information of the current block as the motion information to be used as the final L1 temporal motion information. Here, the predetermined threshold may be determined based on mode information of the current block, motion information of the current block, mode information of neighboring blocks, and/or motion information of neighboring blocks, and the like, 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 temporally derived based on the collocated block as described above, and the L0 input reference picture index and the L1 input reference picture index may be spatially derived from the reconstructed neighboring block. It may be a derived reference picture index. In this case, the L0 input reference picture index and the L1 input reference picture index may be set to the smallest non-negative value among the reference picture indices 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 a reconstructed neighboring block.

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

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

Also, in the above-described embodiments, the reset L1 temporal motion information may be identical to 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 reset the prediction direction information of the current block to unidirectional prediction. At this time, the encoder and 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 as a combined combination with the above-described embodiments.

* FIG. 15 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of deriving temporal motion information according to the embodiment of FIG. 14 . The inter-prediction device according to the embodiment of FIG. 15 may include a temporal motion information determination unit 1510, a motion estimation 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 collocated block corresponding to a current block in an already reconstructed collocated picture. Here, the collocated picture may, for example, correspond to one picture among reference pictures included in the reference picture list. The encoder and the decoder may determine a predetermined relative position based on a block existing at the same spatial position as the current block in the collocated picture, and determine the determined predetermined relative position (eg, spatially identical to the current block). The collocated block may be derived based on a location inside and/or outside a block existing at the location. Temporal motion information derived based on the collocated block may include prediction direction information, an L0 reference picture number, an L1 reference picture number, an L0 motion vector, and an L1 motion vector.

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

If the L0 input temporal motion information and the L1 input temporal motion information are not the same, the inter prediction device may use the input temporal motion information as it is as the temporal motion information of the current block. When AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate for the current block. Also, 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 determiner 1510 determines 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 collocated block. 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 the L1 input reference picture number In the same case, a process by the motion predictor 1520 may be performed. As another example, when the prediction direction of the collocated block is bidirectional prediction, the input temporal motion information may be used as the temporal motion information of the current block as it is, and if the prediction direction of the collocated block is unidirectional prediction, the process by the motion predictor 1520 may be performed.

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

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

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

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

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

The above-described embodiments of FIGS. 6 to 15 may be applied individually, but may also be combined and applied in various ways according to the coding mode of each block. Hereinafter, in embodiments to be described later, a block whose coding mode is a merge mode is referred to as a merge block. Blocks that are not merge blocks may include, for example, blocks whose encoding mode is the AMVP mode. In addition, in embodiments to be described later, the current block may correspond to either a merge block or a non-merge block according to circumstances.

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

As another embodiment, the temporal motion information derivation method according to the embodiments of FIGS. 9 to 11 may be applied to the merge block, and the temporal motion information derivation method according to FIGS. 14 and 15 may be applied to blocks other than the merge block. At this time, in the merge block, if the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the newly derived collocated block, not the collocated block used to derive the input temporal motion information, is the final L1 temporal motion information of the current block. can be used as Also, in a block other than a merge block, when L0 input temporal motion information and L1 input temporal motion information are the same, motion information of an L1 reference picture may be used as final L1 temporal motion information of the current block.

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

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

In the foregoing embodiments, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of steps, and some steps may occur in a different order or concurrently with other steps as described above. can In addition, those skilled in the art will understand that the steps shown in the flow chart are not exclusive, that other steps may be included, or that one or more steps of the flow chart may be deleted without affecting the scope of the present invention. You will understand.

The foregoing embodiment includes examples of various aspects. It is not possible to describe all possible combinations to represent the various aspects, but those skilled in the art will recognize that other combinations are possible. Accordingly, it is intended that the present invention cover all other substitutions, modifications and variations falling within the scope of the following claims.

Claims (2)

In the video encoding method,
determining a prediction mode of a current block as an inter prediction mode;
deriving a motion vector of the current block;
obtaining a prediction sample corresponding to the current block by performing motion compensation on the current block based on the derived motion vector;
obtaining a residual sample for the current block based on the prediction sample;
deriving a spatial motion vector of the current block using spatial neighboring blocks of the current block;
determining a collocated picture of the current block;
deriving a temporal motion vector based on a motion vector of a collocated block corresponding to the current block in the collocated picture; Here, the collocated block is determined according to any one of a first block including the position of the lower-right pixel of the current block or a second block including the center position of the current block, and the collocated block is the first block and determined by scanning the second block according to a preset scan order.
generating a predicted motion vector candidate list for the current block using the spatial motion vector and the temporal motion vector; and
Encoding call picture information for the call picture into a bitstream,
The call picture information is information specifying a picture determined as the call picture of the current block among reference pictures in a reference picture list, and is transmitted to a decoder through the bitstream. In a recording medium containing a bitstream generated by an image encoding method,
The bitstream includes call picture information for a call picture,
determining a prediction mode of a current block as an inter prediction mode based on information included in the bitstream;
deriving a motion vector of the current block;
obtaining a prediction sample corresponding to the current block by performing motion compensation on the current block based on the derived motion vector;
obtaining a residual sample for the current block based on the prediction sample;
deriving a spatial motion vector of the current block by using spatial neighboring blocks of the current block;
determining the collocated picture of the current block;
deriving a temporal motion vector based on a motion vector of a collocated block corresponding to the current block in the collocated picture; Here, the collocated block is determined according to any one of a first block including the position of the lower-right pixel of the current block or a second block including the center position of the current block, and the collocated block is the first block and determined by scanning the second block according to a preset scan order;
generating a predicted motion vector candidate list for the current block using the spatial motion vector and the temporal motion vector; and
Encoding the call picture information for the call picture into the bitstream,
The collocated picture information is information specifying a picture determined as the collocated picture of the current block among reference pictures in a reference picture list, and is signaled to a decoder through the bitstream. A recording medium that stores streams.

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