WO2014003367A1 - Method of decoding image and device using same - Google Patents

Abstract

The present invention relates to a method of predicting an interlayer, and a device using the same, the method including the steps of: creating a first block including a value obtained by up-sampling a reconstructed value of a reference block of a reference layer corresponding to the current block; creating a second block including a prediction value induced based on an intra prediction mode of the current block; and creating a prediction block of the current block by combining the sample values of the first block and the second block. Thus, it is possible to perform intra prediction on the current layer by using intra prediction mode information on another layer.

Description

Image decoding method and apparatus using same

The present invention relates to video compression techniques, and more particularly, to a method and apparatus for performing scalable video coding.

Recently, the demand for high resolution and high quality images is increasing in various applications. As an image has a high resolution and high quality, the amount of information on the image also increases.

As information volume increases, devices with various performances and networks with various environments are emerging. With the emergence of devices of varying performance and networks of different environments, the same content is available in different qualities.

In detail, as the video quality of the terminal device can be supported and the network environment is diversified, in general, video of general quality may be used in one environment, but higher quality video may be used in another environment. .

For example, a consumer who purchases video content on a mobile terminal can view the same video content on a larger screen and at a higher resolution through a large display in the home.

In recent years, as broadcasts with high definition (HD) resolution have been serviced, many users are already accustomed to high-definition and high-definition video.Ultra High Definition (UHD) has more than four times the resolution of HDTV with HDTV. I am also interested in the services of the company.

Therefore, in order to provide various video services required by users in various environments according to the quality, based on a high-efficiency encoding / decoding method for high-capacity video, the quality of the image, for example, the image quality, the resolution of the image, the size of the image, It is necessary to provide scalability in the frame rate of video and the like. In addition, various image processing methods associated with such scalability should be discussed.

An object of the present invention is to provide a method for performing inter prediction on a current layer using information of another layer and an apparatus using the same.

Another object of the present invention is to provide a method for removing candidate redundancy in inter-layer inter prediction and an apparatus using the same.

Another object of the present invention is to provide a method for reducing complexity when removing redundancy of candidates in inter-layer inter prediction and an apparatus using the same.

An embodiment of the present invention provides motion information of adjacent neighboring blocks of a current block, motion information of a COL block corresponding to the current block within a corresponding picture of the current block, and movement of a reference block of a reference layer corresponding to the current block. Constructing a motion prediction list based on the information, and performing inter prediction of the current block based on the motion prediction list, wherein constructing the motion prediction list comprises: motion information of the neighboring block; The method may include determining whether at least one of the motion information of the COL block is overlapped with the reference block.

The configuring of the motion prediction list may include setting motion information of the reference block as a candidate of the motion prediction list, preset motion information among the motion information of at least one neighboring block, and the reference block. And determining the redundancy of the motion information of, and setting the motion information of the neighboring block, which is not the same as the motion information of the reference block, as a candidate of the motion prediction list.

The motion list is a merge candidate list of the current block, and the constituting the motion list may include at least a lowermost block among neighboring blocks adjacent to a left side of the current block and at a rightmost side among neighboring blocks adjacent to an upper end of the current block. Determining validity in order of a located block, an upper right corner block of the current block, a lower left corner block of the current block, and an upper left corner block of the current block; and in the determining of the validity, The redundancy of the motion information of the block located at the lowermost end of the neighboring blocks adjacent to the left side and the block located at the rightmost side of the neighboring blocks adjacent to the top of the current block may be determined.

Alternatively, the motion list is a motion vector predictor list of the current block, and the constituting the motion list may include selecting from a lowermost corner block among a lower left corner block of the current block and a neighboring block adjacent to the left side of the current block. Determining the validity of the second motion information selected from first motion information, an upper right corner block of the current block, a block located at the rightmost side among neighboring blocks adjacent to an upper end of the current block, and an upper left corner block of the current block; In the determining of the validity, at least one of the first motion information and the first motion information and the motion information of the reference block may be determined.

The configuring of the motion prediction list may include setting motion information of the reference block as a candidate of the motion prediction list, and determining redundancy of motion information of the COL block and motion information of the reference block. And, as a result of the determination, if the motion information of the COL block and the motion information of the reference block is not the same, setting the motion information of the COL block as a candidate of the motion prediction list.

According to another exemplary embodiment, the constructing the motion list may include setting motion information of at least one neighboring block as a candidate of the motion prediction list, and preset motion information among the motion information of the at least one neighboring block. Determining the redundancy of the motion information and the motion information of the reference block; and if the predetermined motion information and the motion information of the reference block are not the same as the result of the determination, the motion information of the reference block is candidate of the motion prediction list. It may include the step of setting to.

The constructing the motion prediction list may include setting motion information of the COL block as a candidate of the motion prediction list, determining a redundancy of motion information of the reference block and motion information of the COL block; As a result of the determination, if the motion information of the reference block and the motion information of the COL block are not the same, setting the motion information of the reference block as a candidate of the motion prediction list.

Meanwhile, it may be determined whether the motion information of the neighboring block and the motion information of the reference block overlap with the reference block.

According to another aspect of the present invention, an apparatus for decoding an image may include: motion information of adjacent neighboring blocks of a current block, motion information of a COL block corresponding to the current block in a corresponding picture of the current block, and a reference layer corresponding to the current block. Comprising a motion prediction list based on the motion information of the reference block, and comprises a prediction unit for performing the inter prediction of the current block based on the motion prediction list, the prediction unit of the motion information of the neighboring block and the COL block It may be determined whether at least one of the motion information overlaps with the reference block.

According to an embodiment of the present invention, a method of performing inter prediction on a current layer using information of another layer and an apparatus using the same are provided.

Further, according to an embodiment of the present invention, a method for removing candidate redundancy in inter-layer inter prediction and an apparatus using the same are provided.

In addition, according to an embodiment of the present invention, a method for reducing complexity when removing redundancy of candidates in inter-layer inter prediction and an apparatus using the same are provided.

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

2 is a block diagram schematically illustrating a video decoding apparatus supporting scalability according to an embodiment of the present invention.

3 is a diagram schematically illustrating candidates of motion information used for inter prediction.

 4 is a diagram schematically illustrating a method of deriving motion information of a reference layer according to the present invention.

5 is a diagram schematically illustrating candidates of motion information used when inter prediction is performed in a current layer with reference to a reference layer.

6 is a diagram schematically illustrating a method of scaling mvIL in accordance with the present invention.

7 is a control flowchart illustrating a method of decoding an image according to an embodiment of the present invention.

8 is a control flowchart illustrating a method of constructing a motion candidate list according to an embodiment of the present invention.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the invention to the specific embodiments. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the spirit of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

On the other hand, each of the components in the drawings described in the present invention are shown independently for the convenience of description of the different characteristic functions in the video encoding apparatus / decoding apparatus, each component is a separate hardware or separate software It does not mean that it is implemented. For example, two or more of each configuration may be combined to form one configuration, or one configuration may be divided into a plurality of configurations. Embodiments in which each configuration is integrated and / or separated are also included in the scope of the present invention without departing from the spirit of the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. Hereinafter, the same reference numerals are used for the same components in the drawings, and redundant description of the same components is omitted.

In a video coding method supporting scalability (hereinafter, referred to as 'scalable coding'), input signals may be processed for each layer. Depending on the layer, the input signals (input images) may differ in at least one of resolution, frame rate, bit-depth, color format, and aspect ratio. Can be.

In the present specification, scalable coding includes scalable encoding and scalable decoding.

In scalable encoding / decoding, prediction between layers is performed by using differences between layers, that is, based on scalability, thereby reducing overlapping transmission / processing of information and increasing compression efficiency.

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

Referring to FIG. 1, the encoding apparatus 100 includes an encoder 105 for layer 1 and an encoder 135 for layer 0.

Layer 0 may be a base layer, a reference layer, or a lower layer, and layer 1 may be an enhancement layer, a current layer, or an upper layer.

The encoding unit 105 of the layer 1 includes a prediction unit 110, a transform / quantization unit 115, a filtering unit 120, a decoded picture buffer (DPB) 125, an entropy coding unit 130, and a MUX (Multiplexer, 165).

The encoding unit 135 of the layer 0 includes a prediction unit 140, a transform / quantization unit 145, a filtering unit 150, a DPB 155, and an entropy coding unit 160.

The prediction units 110 and 140 may perform inter prediction and intra prediction on the input image. The prediction units 110 and 140 may perform prediction in predetermined processing units. The performing unit of prediction may be a coding unit (CU), a prediction unit (PU), or a transform unit (TU).

For example, the prediction units 110 and 140 may determine whether to apply inter prediction or intra prediction in a CU unit, determine a mode of prediction in a PU unit, and perform prediction in a PU unit or a TU unit. have. Prediction performed includes generation of a prediction block and generation of a residual block (residual signal).

Through inter prediction, a prediction block may be generated by performing prediction based on information of at least one picture of a previous picture and / or a subsequent picture of the current picture. Through intra prediction, prediction blocks may be generated by performing prediction based on pixel information in a current picture.

As a mode or method of inter prediction, there are a skip mode, a merge mode, a motion vector predictor (MVP) mode method, and the like. In inter prediction, a reference picture may be selected with respect to the current PU that is a prediction target, and a reference block corresponding to the current PU may be selected within the reference picture. The prediction units 110 and 140 may generate a prediction block based on the reference block.

The prediction block may be generated in integer sample units or may be generated in integer or less pixel units. In this case, the motion vector may also be expressed in units of integer pixels or units of integer pixels or less.

In inter prediction, motion information, that is, information such as an index of a reference picture, a motion vector, and a residual signal, is entropy encoded and transmitted to a decoding apparatus. When the skip mode is applied, residuals may not be generated, transformed, quantized, or transmitted.

In intra prediction, the prediction mode may have 33 directional prediction modes and at least two non-directional modes. The non-directional mode may include a DC prediction mode and a planner mode (Planar mode). In intra prediction, a prediction block may be generated after applying a filter to a reference sample.

The PU may be a block of various sizes / types, for example, in the case of inter prediction, the PU may be a 2N × 2N block, a 2N × N block, an N × 2N block, an N × N block (N is an integer), or the like. In the case of intra prediction, the PU may be a 2N × 2N block or an N × N block (where N is an integer). In this case, the PU of the N × N block size may be set to apply only in a specific case. For example, the NxN block size PU may be used only for the minimum size CU or only for intra prediction. In addition to the above-described PUs, PUs such as N × mN blocks, mN × N blocks, 2N × mN blocks, or mN × 2N blocks (m <1) may be further defined and used.

In addition, the prediction unit 110 may perform prediction for layer 1 using the information of the layer 0. In the present specification, a method of predicting information of a current layer using information of another layer is referred to as inter-layer prediction for convenience of description.

Information of the current layer that is predicted using information of another layer (ie, predicted by inter-layer prediction) may include texture, motion information, unit information, predetermined parameters (eg, filtering parameters, etc.).

In addition, information of another layer used for prediction for the current layer (ie, used for inter-layer prediction) may include texture, motion information, unit information, and predetermined parameters (eg, filtering parameters).

As an example of inter-layer prediction, inter-layer motion prediction is also referred to as inter-layer inter prediction. According to inter-layer inter prediction, prediction of a current block of layer 1 (current layer or enhancement layer) may be performed using motion information of layer 0 (reference layer or base layer).

In case of applying inter-layer inter prediction, motion information of a reference layer may be scaled.

As another example of inter-layer prediction, inter-layer texture prediction is also called inter-layer intra prediction or intra base layer (BL) prediction. Inter layer texture prediction may be applied when a reference block in a reference layer is reconstructed by intra prediction.

In inter-layer intra prediction, the texture of the reference block in the reference layer may be used as a prediction value for the current block of the enhancement layer. In this case, the texture of the reference block may be scaled by upsampling.

In another example of inter-layer prediction, inter-layer unit parameter prediction derives unit (CU, PU, and / or TU) information of a base layer and uses it as unit information of an enhancement layer, or based on unit information of a base layer. Unit information may be determined.

In addition, the unit information may include information at each unit level. For example, in the case of CU information, information about a partition (CU, PU and / or TU) may include information on transform, information on prediction, and information on coding. In the case of PU information, information on a PU partition and information on prediction (eg, motion information, information on a prediction mode, etc.) may be included. The information about the TU may include information about a TU partition, information on transform (transform coefficient, transform method, etc.).

In addition, the unit information may include only the partition information of the processing unit (eg, CU, PU, TU, etc.).

In another example of inter-layer prediction, inter-layer parameter prediction may derive a parameter used in the base layer to reuse it in the enhancement layer or predict a parameter for the enhancement layer based on the parameter used in the base layer.

As an example of interlayer prediction, interlayer texture prediction, interlayer motion prediction, interlayer unit information prediction, and interlayer parameter prediction have been described. However, the interlayer prediction applicable to the present invention is not limited thereto.

For example, the prediction unit 110 may use interlayer residual prediction, which predicts the residual of the current layer using the residual information of another layer as interlayer prediction, and performs prediction on the current block in the current layer based on the prediction. It may be.

In addition, the prediction unit 110 may predict the current block in the current layer by using a difference (differential image) image between the reconstructed picture of the current layer and the resampled picture of another layer as the inter-layer prediction. Inter-layer difference prediction may be performed.

In addition, the prediction unit 110 may use interlayer syntax prediction that predicts or generates a texture of a current block using syntax information of another layer as interlayer prediction. In this case, the syntax information of the reference layer used for prediction of the current block may be information about an intra prediction mode, motion information, and the like.

In this case, inter-layer syntax prediction may be performed by referring to the intra prediction mode from a block to which the intra prediction mode is applied in the reference layer and referring to motion information from the block MV to which the inter prediction mode is applied.

For example, although the reference layer is a P slice or a B slice, the reference block in the slice may be a block to which an intra prediction mode is applied. In this case, when inter-layer syntax prediction is applied, inter-layer prediction may be performed to generate / predict a texture for the current block by using an intra prediction mode of the reference block among syntax information of the reference layer.

Multiple prediction methods using the above-described interlayer may be used when predicting a specific block. For example, the prediction information of the layer 0 may be used to predict the current block while additionally using unit information or filtering parameter information of the corresponding layer 0 or the corresponding block. This combination of inter-layer prediction methods can also be applied to the predictions described below in this specification.

The transform / quantization units 115 and 145 may perform transform on the residual block in transform block units to generate transform coefficients and quantize the transform coefficients.

The transform block is a block of samples and is a block to which the same transform is applied. The transform block can be a transform unit (TU) and can have a quad tree structure.

The transform / quantization units 115 and 145 may generate a 2D array of transform coefficients by performing transform according to the prediction mode applied to the residual block and the size of the block. For example, if intra prediction is applied to a residual block and the block is a 4x4 residual array, the residual block is transformed using a discrete sine transform (DST), otherwise the residual block is transformed into a discrete cosine transform (DCT). Can be converted using.

The transform / quantization unit 115 and 145 may quantize the transform coefficients to generate quantized transform coefficients.

The transform / quantization units 115 and 145 may transfer the quantized transform coefficients to the entropy coding units 130 and 180. In this case, the transform / quantization unit 145 may rearrange the two-dimensional array of quantized transform coefficients into one-dimensional arrays according to a predetermined scan order and transfer them to the entropy coding units 130 and 180. In addition, the transform / quantizers 115 and 145 may transfer the reconstructed block generated based on the residual and the predictive block to the filtering units 120 and 150 for inter prediction.

Meanwhile, the transform / quantization units 115 and 145 may skip transform and perform quantization only or omit both transform and quantization as necessary. For example, the transform / quantization unit 115 or 165 may omit the transform for a block having a specific prediction method or a specific size block, or a block of a specific size to which a specific prediction block is applied.

The entropy coding units 130 and 160 may perform entropy encoding on the quantized transform coefficients. Entropy encoding may use, for example, an encoding method such as Exponential Golomb, Context-Adaptive Binary Arithmetic Coding (CABAC), or the like.

The filtering units 120 and 150 may apply a deblocking filter, an adaptive loop filter (ALF), and a sample adaptive offset (SAO) to the reconstructed picture.

The deblocking filter may remove distortion generated at the boundary between blocks in the reconstructed picture. The adaptive loop filter (ALF) may perform filtering based on a value obtained by comparing the reconstructed image with the original image after the block is filtered through the deblocking filter. The SAO restores the offset difference from the original image on a pixel-by-pixel basis to the residual block to which the deblocking filter is applied, and is applied in the form of a band offset and an edge offset.

The filtering units 120 and 150 may apply only the deblocking filter, only the deblocking filter and the ALF, or may apply only the deblocking filter and the SAO without applying all of the deblocking filter, ALF, and SAO.

The DPBs 125 and 155 may receive the reconstructed block or the reconstructed picture from the filtering units 120 and 150 and store the received reconstruction picture. The DPBs 125 and 155 may provide a reconstructed block or picture to the predictors 110 and 140 that perform inter prediction.

Information output from the entropy coding unit 160 of layer 0 and information output from the entropy coding unit 130 of layer 1 may be multiplexed by the MUX 185 and output as a bitstream.

Meanwhile, for the convenience of description, the encoding unit 105 of the layer 1 has been described as including the MUX 165. However, the MUX is separate from the encoding unit 105 of the layer 1 and the encoding unit 135 of the layer 0. It may be a device or a module of.

The encoding device of FIG. 1 may be implemented as an electronic device capable of capturing and encoding an image, including a camera. For example, the encoding device may be implemented in or included in a personal terminal such as a television, computer system, portable telephone or tablet PC, or the like.

2 is a block diagram illustrating an example of interlayer prediction in an encoding apparatus that performs scalable coding according to the present invention.

Referring to FIG. 2, the decoding apparatus 200 includes a decoder 210 of layer 1 and a decoder 250 of layer 0.

Layer 0 may be a base layer, a reference layer, or a lower layer, and layer 1 may be an enhancement layer, a current layer, or an upper layer.

The decoding unit 210 of the layer 1 includes an entropy decoding unit 215, a reordering unit 220, an inverse quantization unit 225, an inverse transform unit 230, a prediction unit 235, a filtering unit 240, and a memory. can do.

The decoding unit 250 of the layer 0 includes an entropy decoding unit 255, a reordering unit 260, an inverse quantization unit 265, an inverse transform unit 270, a prediction unit 275, a filtering unit 280, and a memory 285. ) May be included.

When the bitstream including the image information is transmitted from the encoding device, the DEMUX 205 may demultiplex the information for each layer and deliver the information to the decoding device for each layer.

The entropy decoding units 215 and 255 may perform entropy decoding corresponding to the entropy coding scheme used in the encoding apparatus. For example, when CABAC is used in the encoding apparatus, the entropy decoding units 215 and 255 may also perform entropy decoding using CABAC.

Information for generating a prediction block among the information decoded by the entropy decoding units 215 and 255 is provided to the prediction units 235 and 275, and a residual value of which entropy decoding is performed by the entropy decoding units 215 and 255. That is, the quantized transform coefficients may be input to the reordering units 220 and 260.

The reordering units 220 and 260 may rearrange the information of the bitstreams entropy decoded by the entropy decoding units 215 and 255, that is, the quantized transform coefficients, based on the reordering method in the encoding apparatus.

For example, the reordering units 220 and 260 may rearrange the quantized transform coefficients of the one-dimensional array into the coefficients of the two-dimensional array. The reordering units 220 and 260 may generate a two-dimensional array of coefficients (quantized transform coefficients) by performing scanning based on the prediction mode applied to the current block (transform block) and / or the size of the transform block.

The inverse quantizers 225 and 265 may generate transform coefficients by performing inverse quantization based on the quantization parameter provided by the encoding apparatus and the coefficient values of the rearranged block.

The inverse transform units 230 and 270 may perform inverse transform on the transform performed by the transform unit of the encoding apparatus. The inverse transform units 230 and 270 may perform inverse DCT and / or inverse DST on a discrete cosine transform (DCT) and a discrete sine transform (DST) performed by an encoding apparatus.

The DCT and / or DST in the encoding apparatus may be selectively performed according to a plurality of pieces of information, such as a prediction method, a size of a current block, and a prediction direction, and the inverse transformers 230 and 270 of the decoding apparatus may perform transform information performed in the encoding apparatus. Inverse transformation may be performed based on.

For example, the inverse transform units 230 and 270 may apply inverse DCT and inverse DST according to a prediction mode / block size. For example, the inverse transformers 230 and 270 may apply an inverse DST to a 4x4 luma block to which intra prediction is applied.

In addition, the inverse transform units 230 and 270 may fixedly use a specific inverse transform method regardless of the prediction mode / block size. For example, the inverse transform units 330 and 370 may apply only inverse DST to all transform blocks. In addition, the inverse transform units 330 and 370 may apply only inverse DCT to all transform blocks.

The inverse transform units 230 and 270 may generate a residual or residual block by inversely transforming the transform coefficients or the block of the transform coefficients.

The inverse transformers 230 and 270 may also skip the transformation as needed or in accordance with the manner encoded in the encoding apparatus. For example, the inverse transforms 230 and 270 may omit the transform for a block having a specific prediction method or a specific size or a block of a specific size to which a specific prediction block is applied.

The prediction units 235 and 275 may perform prediction on the current block based on prediction block generation related information transmitted from the entropy decoding units 215 and 255 and previously decoded blocks and / or picture information provided by the memories 245 and 285. A prediction block can be generated.

When the prediction mode for the current block is an intra prediction mode, the prediction units 235 and 275 may perform intra prediction on the current block based on pixel information in the current picture.

When the prediction mode for the current block is the inter prediction mode, the prediction units 235 and 275 may perform information on the current block based on information included in at least one of a previous picture or a subsequent picture of the current picture. Inter prediction may be performed. Some or all of the motion information required for inter prediction may be derived from the information received from the encoding apparatus and correspondingly.

When the skip mode is applied as the mode of inter prediction, residual is not transmitted from the encoding apparatus, and the prediction block may be a reconstruction block.

Meanwhile, the prediction unit 235 of layer 1 may perform inter prediction or intra prediction using only information in layer 1, or may perform inter layer prediction using information of another layer (layer 0).

For example, the prediction unit 235 of the layer 1 may perform prediction on the current block by using one of the motion information of the layer 1, the texture information of the layer 1, the unit information of the layer 1, and the parameter information of the layer 1.

The predictor 235 of the layer 1 may receive motion information of the layer 1 from the predictor 275 of the layer 0 to perform motion prediction. Inter-layer motion prediction is also called inter-layer inter prediction. By inter-layer motion prediction, prediction of a current block of a current layer (enhanced layer) may be performed using motion information of a reference layer (base layer). The prediction unit 335 may scale and use motion information of the reference layer when necessary.

The predictor 235 of the layer 1 may receive texture information of the layer 0 from the predictor 275 of the layer 0 to perform texture prediction. Texture prediction is also called inter layer intra prediction or intra base layer (BL) prediction. Texture prediction may be applied when the reference block of the reference layer is reconstructed by intra prediction. In inter-layer intra prediction, the texture of the reference block in the reference layer may be used as a prediction value for the current block of the enhancement layer. In this case, the texture of the reference block may be scaled by upsampling.

The predictor 235 of the layer 1 may receive unit parameter information of the layer 0 from the predictor 275 of the layer 0 to perform unit parameter prediction. By unit parameter prediction, unit (CU, PU, and / or TU) information of the base layer may be used as unit information of the enhancement layer, or unit information of the enhancement layer may be determined based on unit information of the base layer.

The predictor 235 of the layer 1 may perform parameter prediction by receiving parameter information regarding the filtering of the layer 0 from the predictor 275 of the layer 0. By parameter prediction, the parameters used in the base layer can be derived and reused in the enhancement layer, or the parameters for the enhancement layer can be predicted based on the parameters used in the base layer.

Multiple prediction methods using the above-described interlayer may be used when predicting a specific block. For example, the prediction information of the layer 0 may be used to predict the current block while additionally using unit information or filtering parameter information of the corresponding layer 0 or the corresponding block. This combination of inter-layer prediction methods can also be applied to the predictions described below in this specification.

The adders 290 and 295 may generate a reconstruction block using the prediction blocks generated by the predictors 235 and 275 and the residual blocks generated by the inverse transformers 230 and 270. In this case, the adders 290 and 295 can be viewed as separate units (restore block generation unit) for generating the reconstruction block.

Blocks and / or pictures reconstructed by the adders 290 and 295 may be provided to the filtering units 240 and 280.

Referring to the example of FIG. 2, the filtering unit 240 of the layer 1 filters the reconstructed picture by using parameter information transmitted from the predicting unit 235 of the layer 1 and / or the filtering unit 280 of the layer 0. You can also do For example, in layer 1, the filtering unit 240 may apply filtering to or between layers using the parameters predicted from the parameters of the filtering applied in the layer 0.

The memories 245 and 285 may store the reconstructed picture or block to use as a reference picture or reference block. The memories 245 and 285 may output the stored reconstructed picture through a predetermined output unit (not shown) or a display (not shown).

In the example of FIG. 2, the reordering unit, the inverse quantization unit, and the inverse transform unit have been described. However, as in the encoding apparatus of FIG. 1, the decoding apparatus is configured to perform reordering, inverse quantization, and inverse transformation in order in one module of the inverse quantization / inverse transformation unit. It can also be configured.

In the example of FIGS. 1 and 2, the prediction unit has been described, but for better understanding, the prediction unit of layer 1 may be different from the interlayer prediction unit that performs prediction using information of another layer (layer 0). It may also be regarded as including an inter / intra predictor for performing prediction without using the information of).

The decoding apparatus of FIG. 2 may be implemented as various electronic devices capable of playing back, or playing back and displaying an image. For example, the decoding device may be implemented in or included in a set-top box, a television, a computer system, a portable telephone, a personal terminal such as a tablet PC, or the like.

Due to the characteristics of an image including a plurality of layers, there is a strong correlation between the reference layer and the current layer. In scalable video coding using the correlation, the information of the current picture is predicted by using the reference picture information. Inter-layer prediction may be performed.

Inter-layer inter prediction is also called inter-layer motion prediction, and in the present specification, inter layer motion prediction and expression of inter-layer inter prediction may be mixed as necessary for better understanding of the present invention.

In inter-layer motion prediction, prediction of a current block of a current layer (enhanced layer) may be performed using motion information of a reference layer (base layer). Inter-layer motion prediction may be performed by the predictors 110 and 235 of FIGS. 1 and 2.

3 briefly illustrates an example of candidates for motion information used when inter prediction is performed in a layer without referring to another layer (hereinafter, referred to as 'inter prediction').

In FIG. 3, A0, A1, B0, B1, B2, and COL may indicate a corresponding block or may indicate motion information of the corresponding block. In this case, the motion information of the corresponding block may be a motion vector or a motion vector and a reference picture index.

Here, the case of the base layer will be described as an example of the inter prediction method.

Inter prediction in the base layer may be performed by the prediction units 140 and 275 of FIGS. 1 and 2.

The modes of inter prediction include a merge mode, a skip mode, and a mode using a motion vector predicot (MVP). The mode using the MVP may be referred to as an advanced MVP (AMVP) mode for convenience of description.

In the merge mode, motion information selected from motion information (hereinafter, referred to as motion information candidates) of neighboring blocks illustrated in FIG. 3 may be used as motion information of the current block. It can be transmitted from the encoding device indicating the selected motion information candidate to the decoding device.

In the skip mode, the motion information of the motion information candidate selected as in the merge mode is used as the motion information of the current block, but the residual is not generated / transmitted.

When the merge mode or the skip mode is applied, the prediction unit may determine the availability for the spatial candidates A0, A1, B0, B1, and B2 around the current block. Availability determination may proceed in a predetermined order. For example, the process may proceed in the order of A1 → B1 → B0 → A1 → B2.

In this case, the availability determination of each candidate may include determining the sameness as the previous candidate. For example, with regard to B1, availability determination may be made in consideration of whether A1 and motion information are the same. Specifically, if A1 is available and the motion information of A1 and B1 is the same, it may be determined that B1 is not available.

In the same manner, B0 may determine availability by considering whether motion information is identical to B1, and A0 may determine availability by considering whether motion information is identical to A1.

B2 may determine availability by considering whether both A1 and motion information are the same and whether B1 and motion information are the same.In this case, when all four previous candidates (A0, A1, B0, and B1) are available, they are not available. It can also be judged.

When a COL candidate is used, a COL picture including a COL candidate may be specified using a reference picture list. Motion information of a prediction block including a predetermined position with respect to a COL block in the same coding tree block (CTB) as the current block may be used as a COL candidate. In this case, the motion vector of the COL candidate may be scaled in consideration of the COL picture and the reference pictures of the current picture, and the reference index of the COL candidate may be set to a predetermined value (eg, 0).

With candidates determined to be available including COL candidates, a merge candidate list may be constructed according to the availability determination order.

In this case, when the slice type of the current block is B (ie, a slice to which bidirectional prediction is applied) and the number of candidates included in the current merge candidate list is less than the maximum number, candidates (combined amount prediction candidates, combined bi) are included in the merge candidate list. Prediction candidates may be added.

As described above, if the number of candidates included in the merge candidate list is smaller than the maximum number even after the merge candidate list is configured, a predetermined candidate (eg, zero merge candidate) may be added to the merge candidate list.

The prediction unit may perform inter prediction by using motion information of a candidate indicated by information transmitted from the encoding apparatus (eg, merge index merge_idx) on the merge candidate list as motion information for the current block. For example, the prediction unit may use the samples indicated by the motion information of the candidate selected by the merge index as the prediction block of the current block.

On the other hand, even when the AMVP mode is applied, the prediction unit may construct an AMVP list composed of MVP candidates.

In the AMVP mode, the prediction unit determines the availability of the candidate from A0 → A1, and determines the availability of the candidate from B0 → B1 → B2.

In determining the availability of the candidate in the order of A0 → A1, the prediction unit may include the candidate in the AMVP list when there is a candidate having the same reference picture as the current block as an available candidate. If no candidate satisfies ①, the prediction unit is first searched as available based on the difference in POC (Picture Order Count) between the current picture and the reference picture of the current picture and the POC difference between the current picture and the reference picture of the candidate. The motion vector of the candidate may be scaled. The prediction unit may include the scaled motion vector in the AMVP list.

In determining the availability of the candidates in the order of B0-> B1-> B2, the prediction unit includes the candidate in the AMVP list if there are candidates having the same reference picture as the current block as available candidates. When no candidate satisfies ① and no candidates are available among A0 and A1, the prediction unit includes a ② picture order count (POC) difference between the current picture and the reference picture of the current picture, and a POC difference between the current picture and the reference picture of the candidate. Based on, it is possible to scale the motion vector of the candidate found first as available. The prediction unit may include the scaled motion vector in the AMVP list.

In the case of using a COL candidate (temporal candidate), a COL picture including a COL candidate may be specified using a reference picture list. The motion information of the prediction block including the predetermined position with respect to the COL block in the same CTB as the current block may be used as a COL candidate. In this case, the motion vector of the COL candidate may be scaled in consideration of the COL picture and reference pictures of the current picture.

The MVP candidate determined by judging the availability of the candidate in the order of A0 → A1 is called A, and the MVP candidate determined by judging the availability of the candidate in the order of B0 → B1 → B2 is called B, and the availability of the temporal candidate is determined by When the determined MVP candidate is called COL, the AMVP list may be configured in the order of [AB COL].

In this case, when A and B are the same, the prediction unit may delete one of them from the AMVP list.

The prediction unit may adjust the number of MVP candidates in the AMVP list to 2 when all of A, B, and COL are valid. For example, the prediction unit may configure the AMVP list with A and B, and remove the COL from the AMVP list.

The predictor may add zero motion vectors as candidates when the number of candidates in the AMVP list is less than two.

The encoding apparatus decodes an MVP index indicating an MVP to use for inter prediction on a current block on an AMVP list, a motion vector difference (mvd) of a motion vector, and a reference index indicating a reference picture for a current picture on a reference picture list. Can be sent to. The reference picture list is a list of reference pictures that can be used for inter prediction, and there are L0 for forward prediction and L1 for backward prediction.

The prediction unit may generate a prediction block for the current block based on the motion vector derived from the MVP and the mvd indicated by the MVP index and the reference picture indicated by the reference index.

When the prediction block is generated by applying the merge mode / skip mode or the AMVP mode, the prediction unit may generate a reconstruction block for the current block based on the prediction block and the residual. Since the residual is not transmitted when the skip mode is applied, the prediction unit may use the prediction block as the reconstruction block.

Until now, the case of the base layer (layer 0) has been described as an example of inter prediction. However, when the inter prediction is performed without using information of another layer in the enhancement layer (layer 1), the inter prediction is performed in the same manner as described above. You can make predictions.

When inter prediction is performed on the base layer as described above, the enhancement layer may perform inter-layer motion prediction using motion information of the base layer.

Inter-layer motion prediction may be performed by the prediction units of the encoding apparatus and the decoding apparatus.

Hereinafter, inter-layer intra prediction according to the present invention will be described in detail with reference to the drawings.

 1. Derivation of motion information of reference layer

4 is a diagram schematically illustrating a method of deriving motion information of a reference layer according to the present invention. In FIG. 4, a case in which the current layer is an upper layer of the reference layer and the resolution of the current layer is higher than the resolution of the reference layer will be described as an example.

Referring to FIG. 4, a current PU may be specified based on a PU 400 of a reference layer corresponding to a PU 410 of the current layer (current PU).

Let the position specifying the current PU be (xCurr, yCurr), and the position of the reference ray corresponding to the current PU, for example, the position specifying the reference PU, be (xRef, yRef).

Let the inter-layer motion vector to be derived from the motion vector of the reference layer be mvIL, and the motion vector (eg, the motion vector of the reference PU) specified by (xRef, yRef) be mvRL.

In FIG. 4, nPSW is the width of the current PU 410, and nPSH is the height of the current PU 410.

The prediction unit may specify a current PU and specify a reference PU based on the location of the current PU to derive motion information (eg, a motion vector) of the reference PU.

 (1) Determine the position (xCurr, yCurr) specifying the current PU

The position (xCurr, yCurr) that specifies the current PU may be determined by any one of the following candidates, such as?

① LT = (xP, yP)

② RT = (xP + nPSW-1, yP)

③ LB = (xP, yP + nPSH-1)

④ RB = (xP + nPSW-1, yP + nPSH-1)

⑤ LT '= (xP-1, yP-1)

⑥ RT ’= (xP + nPSW, yP-1)

⑦ LB ’= (xP-1, yP + nPSH)

⑧ RB '= (xP + nPSW, yP + nPSH)

⑨ C0 = (xP + (nPSW >> 1) -1, yP + (nPSH >> 1) -1)

⑩ C1 = (xP + (nPSW >> 1), yP + (nPSH >> 1) -1)

2 C2 = (xP + (nPSW >> 1) -1, yP + (nPSH >> 1))

3 C3 = (xP + (nPSW >> 1), yP + (nPSH >> 1))

The position (xCurr, yCurr) that specifies the current PU may be determined and used in any one of ① to ,, or may be signaled to determine which position (xCurr, yCurr) to use after determining through RDO in the encoding apparatus. .

Alternatively, the same position may be determined as the position specifying the PU of the current layer (enhanced layer) in response to the position specifying the PU in the reference layer (base layer). For example, when the upper left end of the PU is used as a position for specifying the PU in the reference layer, the upper left LT = (xP, yP) in the PU may be determined and used as (xCurr, yCurr) in the current layer.

 (2) the target position of the reference layer (xRef, yRef)

A position to obtain a motion vector in the reference layer (the position of the reference PU) may be determined according to the ratio between the current layer and the reference layer from the position of the current PU.

Equation 1 shows a method of determining a position to obtain a motion vector in a reference layer according to the present invention.

<Equation 1>

xRef = xCurr / scale

yRef = yCurr / scale

In this case, the scale representing the ratio of the current layer to the reference layer may be determined according to two layer resolutions. For example, if the resolution of the current layer is twice the resolution of the reference layer, the value of scale applied is 2. If the resolution of the current layer is the same as that of the reference layer, the scale applied is 1.

Here, although the value of scale is determined as the resolution ratio between the current layer and the reference layer, the present invention is not limited thereto. The scale may be determined according to the type of scalability applied between the current layer and the reference layer. For example, scale may be a picture size ratio and a frame rate ratio between the current layer and the reference layer.

The prediction unit may derive the motion vector of the position (xRef, yRef), that is, the motion vector of the PU (reference PU) covering (xRef, yRef) as mvRL.

In addition, the prediction unit may derive the reference index of the PU (reference PU) covering (xRef, yRef) as the reference index refIdxIL to be used for inter-layer motion prediction.

The prediction unit may induce a motion vector mvIL to be used for inter-layer motion prediction (inter-layer inter prediction) by scaling mvRL.

Equation 2 shows a method of inducing mvIL by scaling mvRL according to the present invention.

<Formula 2>

mvIL = scale * mvRL

In Equation 2, the coefficient scale represents the ratio of the current layer to the reference layer as in Equation 1. For example, if the resolution of the current layer is twice the resolution of the reference layer, the value of scale applied is 2.

If the resolution of the current layer is the same as that of the reference layer, the applied scale value is 1, and the prediction unit may use mvRL as mvIL.

2. Interlayer Inter Prediction Using Motion Information Derived from Reference Layer

The prediction unit may perform interlayer inter prediction on the current block of the current layer (enhanced layer) using motion information derived from the reference layer. The motion information derived from the reference layer includes a motion vector mvIL and a reference index refIdxIL.

For example, when the merge mode / skip mode is applied, the prediction unit may add mvIL and refIdxIL as merge candidates to the merge candidate list for the current block.

In addition, when the AMVP mode is applied, the prediction unit may add mvIL as an MVP candidate to the AMVP list for the current block.

(1) When merge mode is applied

As described above, Table 1 shows an example of a merge candidate list configured when merge mode is applied in a layer without referring to another layer as inter prediction.

Table 1

In Table 1, A1, B1, B0, A0, B2 and COL are the same as A1, B1, B0, A0, B2 and COL of FIG. In addition, the method of constructing the merge candidate list of inter prediction in Table 1 is the same as in the merge mode of the inter prediction described above with reference to FIG. 3.

 In Table 1, the candidate located at the top may be assigned the index of the smallest value, and the candidate located at the bottom may be assigned the index of the largest value.

As shown in Table 1, when the inter prediction is performed using information in the current layer without referring to another layer, that is, the reference layer, or when the reference PU of the reference layer is invalid or predicted in the intra mode, the prediction unit A1, B1, B0. The merge candidate list may be derived in consideration of the redundancy of A0 and B2.

As described above, the prediction unit may determine the availability of candidates in the order of A1 → B1 → B0 → A0 → B2, and may exclude candidates from the list in consideration of redundancy when determining availability.

The prediction unit determines the sameness of the motion information with A1 with respect to B1, and adds B1 to the candidate list when the motion information between A1 and B1 is not the same.

Similarly, B0 considers whether the motion information is the same as B1 and the prediction unit may add B0 to the candidate list when the motion information of B0 and B1 is not the same.

The prediction unit A0 may add A1 to the candidate list when the motion information of A0 and A1 is not the same, considering whether A1 is identical to the motion information.

B2 may determine availability by considering whether both A1 and motion information are the same and whether B1 and motion information are the same.In this case, when all four previous candidates (A0, A1, B0, and B1) are available, they are not available. It can also be judged. The predictor may add B2 to the candidate list when the motion information of B2 is different from the motion information of A1 and B1, and all four previous candidates A0, A1, B0, and B1 are not available.

The prediction unit may determine the availability of the COL candidates, and may construct a merge candidate list according to the availability determination order, from the candidates determined to be available including the COL candidates.

In this case, when the number of candidates currently included in the merge candidate list is less than the maximum number, the prediction unit may add candidates (combined bi-prediction candidates) to the merge candidate list.

As described above, if the number of candidates included in the merge candidate list is smaller than the maximum number even after the merge candidate list is configured, a predetermined candidate (eg, zero merge candidate) may be added to the merge candidate list.

In addition, the predictor may determine the identity between A1, B1, B0, A0, B2, and COL at a time after constructing a list by excluding the identity between A1, B1, B0, A0, and B2. In this case, the task of leaving one of the same candidates may be performed after determining the validity of the COL.

On the other hand, when inter-layer motion prediction is applied, unlike the Table 1, the prediction unit may construct a merge candidate list including motion information derived from a reference layer.

5 briefly illustrates an example of candidates for motion information used when inter prediction is performed in a current layer with reference to a reference layer.

In FIG. 5, A 0, A 1, B 0, B 1, B 2, COL, and REF may indicate a corresponding block or may indicate motion information of the corresponding block. In this case, the motion information of the corresponding block may be a motion vector or a motion vector and a reference picture index.

For convenience of explanation, the motion information derived from the reference layer is referred to as a reference layer candidate REF. REF includes mvIL and refIdxIL.

A0, A1, B0, B1, B2, and COL of FIG. 5 are the same as A0, A1, B0, B1, B2, and COL of FIG. 3, and merge candidate lists using A0, A1, B0, B1, B2, and COL. The method of constructing is also the same as described above with reference to FIG.

Table 2 shows an example of a merge candidate list configured by the prediction unit when the merge mode of inter-layer motion prediction is applied according to the present invention. Table 2 describes the order in which reference layer candidates are added to the merge candidate list according to the present invention.

TABLE 2

In Table 2, the topmost candidate may be assigned the smallest index, and the bottommost candidate may be assigned the largest index.

When the merge mode of the inter-layer motion prediction is applied, the prediction unit may include the REF in any order of ⓐ to ⓕ in the merge candidate list of Table 2.

For example, the prediction unit may allocate the smallest index (eg, 0) to REF and include it in the order of merge candidate list. That is, the prediction unit may first add REF to the merge candidate list.

In addition, the prediction unit may allocate the largest index (eg, the maximum number of candidates that can be included in the merge candidate list minus 1) to the REF and include it in the order of the merge candidate list. That is, the prediction unit may add the REF to the merge candidate list at the latest.

The prediction unit may add REF to ⓒ which is the order after the spatial candidates. That is, the prediction unit may add the REF to the merge candidate list after determining the validity of the spatial candidates.

In addition, the prediction unit may add REF to ⓓ after the candidates for unidirectional prediction among the candidates in the current layer and before the combined bidirectional candidate. That is, the prediction unit may determine the validity of the candidates of the unidirectional prediction among the candidates in the current layer, and add the REF to the merge candidate list before adding the combined bidirectional candidate.

The prediction unit may add REF to ⓔ, which is an order after considering all candidates in the current layer. That is, the prediction unit may add the REF to the merge candidate list after reviewing all validities of the candidates in the current layer.

In addition, the prediction unit may add REF to ⓑ, which is an order after considering the candidate on the left side of the current block and the candidate on the upper side one by one. That is, the prediction unit may include the REFs in the merge candidate list after examining the validity of the candidate on the left side of the current block and the candidate on the upper side one by one.

The number of candidates included in the merge candidate list of the interlayer motion prediction of Table 2, that is, the maximum number of candidates may be the same as in Table 1. In this case, the candidates of the current layer that are lower than the REF may be excluded from the merge candidate list according to the position where the REF is included to match the maximum number of candidates. In addition, when the maximum number of candidates is satisfied as candidates of the current layer that are higher than REF, the REF may be excluded from the merge candidate list.

The number of candidates included in the merge candidate list of the interlayer motion prediction of Table 2, that is, the maximum number of candidates may be different from that of Table 1. For example, the maximum number of candidates in Table 2 may be one more than in the case of Table 1 in consideration of REF. In this case, after the merge candidate list is formed of candidates of the current layer, the merge candidate list may be completed by including REF in a predetermined position or a predetermined order. In this case, the position of the REF in the merge candidate list or the order in which the REFs are added may be predetermined, may be indicated by the encoding apparatus, or may be derived by the decoding apparatus.

Which candidate from among the candidates in the merge candidate list is used to perform the merge mode may be indicated from the encoding apparatus. For example, the prediction unit selects a candidate indicated by the information received from the encoding apparatus (for example, merge index merge_idx) on the merge candidate list as shown in Table 2, and selects a prediction block for the current block based on the block indicated by the selected motion information. Can be generated.

(2) When MVP (AMVP) mode is applied

As described above, Table 3 shows an example of a candidate list configured when the MVP mode is applied in the current layer without referring to another layer as inter prediction. In the present specification, a mode of inter prediction using MVP is called an AMVP mode, and a list composed of candidate MVPs used at this time is called an AMVP list.

TABLE 3

In Table 3, A1, B1, B0, A0, B2, COL and A and B are the same as A and B in MVP mode described using A1, B1, B0, A0, B2, COL and FIG. . In addition, the method of constructing the MVP candidate list of inter prediction in Table 3 is the same as in the MVP mode of inter prediction described above with reference to FIG. 3.

In Table 3, the topmost candidate may be assigned the smallest index, and the bottommost candidate may be assigned the largest index.

The prediction unit performs inter prediction using information in the current layer without referring to another layer, that is, the reference layer, or determines the identity between A and B when the reference PU of the reference layer is invalid or predicted in the intra mode. If A and B are the same, one of A and B can be excluded from the AMVP list. This process may be performed when determining the validity of B, may be performed after determining A and B, or may be performed after determining the validity of COL or after determining the validity of COL.

The prediction unit may determine the availability of the COL candidate when the number of candidates included in the AMVP list is A and B less than the maximum number, for example, 2, and add the COL candidates to the AMVP list.

As described above, when the number of candidates included in the AMVP list is smaller than the maximum number even after the AMVP list is configured, the prediction unit may add a predetermined candidate (eg, zero merge candidate) to the merge candidate list.

On the other hand, when inter-layer motion prediction is applied, unlike the Table 3, the prediction unit may construct an MVP candidate list including motion information derived from a reference layer. Here, the motion vector derived from the reference layer is referred to as a reference layer candidate

rence layer candidate) REF may be the REF illustrated in FIG. 5.

Table 4 shows an example of an AMVP list constructed by the prediction unit when the MVP mode of inter-layer motion prediction is applied according to the present invention. Table 4 describes the order in which reference layer candidates are added to the AMVP list according to the present invention.

Table 4

In Table 4, A1, B1, B0, A0, B2, COL and A and B are the same as A and B in MVP mode described using A1, B1, B0, A0, B2, COL and FIG. . In addition, in Table 4, the method of constructing the AMVP list with A, B, and COL is the same as described above with reference to FIG. 3.

In Table 4, the topmost candidate may be assigned the smallest index, and the bottommost candidate may be assigned the largest index.

When the MVP mode of the inter-layer motion prediction is applied, the prediction unit may include the REF in any order of ⓐ to ⓔ in the AMVP list of Table 4.

For example, the prediction unit may allocate the smallest index (eg, 0) to REF and include it in the order of ⓐ. That is, the prediction unit may add REF to the AMVP list first.

In addition, the prediction unit may allocate the largest index (eg, the maximum number of candidates that can be included in the AMVP list minus 1) to the REF and add it to the order of ⓔ. That is, the prediction unit may add REF to the end of the AMVP list.

Also, the prediction unit may include REF in ⓓ which is an order after considering all candidates in the current layer.

The prediction unit may add REF to ⓒ, which is the order after the spatial candidates. In addition, the prediction unit may include the REF in the position ⓑ after considering the candidate on the left side of the current block and before considering the candidate on the upper side.

The number of candidates included in the AMVP list of interlayer motion prediction of Table 4, that is, the maximum number of candidates may be the same as in Table 3. In this case, the candidates of the current layer that is lower than the REF may be excluded from the AMVP list, depending on the position where the REF is included to match the maximum number of candidates. In addition, when the maximum number of candidates is satisfied as candidates of the current layer that are higher than REF, the REF may be excluded from the AMVP list.

For example, when the maximum number of candidates is 2, the REF at position © may be excluded from the AMVP list.

The number of candidates included in the AMVP list of interlayer motion prediction of Table 4, that is, the maximum number of candidates may be different from that of Table 3. For example, the maximum number of candidates in Table 4 may be one more than in the case of Table 3 (eg, 2) in consideration of REF. In this case, the AMVP list may be configured as candidates of the current layer, and then the AMVP list may be completed by including REF in a predetermined position. In this case, the position of the REF in the AMVP list may be predetermined, may be indicated by the encoding apparatus, or may be derived by the decoding apparatus.

Which candidate from among the candidates in the AMVP list is used to perform the MVP mode may be indicated from the encoding apparatus. For example, the prediction unit may select a candidate whose information received from the encoding device indicates on the AMVP list as shown in Table 4, and may derive the motion vector for the current block by using the selected motion vector and mvd received from the encoding device. The prediction unit may generate a prediction block for the current block based on the derived motion vector and the reference picture indicated by the reference index received from the encoding apparatus.

Meanwhile, if a predetermined condition is satisfied, the prediction unit may scale mvIL before adding REF to the AMVP list.

For example, when the reference index of the current PU and the reference index refIdxIL of the reference PU are different, mvIL may be scaled. In other words, when the POC of the picture indicated by the reference index of the current PU (the reference picture of the current PU) and the POC of the picture indicated by the reference index of the reference PU (the reference picture of the reference PU) are different, mvIL can be scaled. have.

6 is a diagram schematically illustrating a method of scaling mvIL in accordance with the present invention.

Referring to FIG. 6, a difference between the POC of the current picture and the POC of the reference picture 620 of the current PU 600 in the current layer is referred to as tb, and the POC of the current picture and the reference picture of the reference PU 610 in the reference layer. The difference between POCs at 630 is called td.

When the pocRef, which is the POC for the reference picture 620 of the current PU 600, and the pocRefLayer, which is the POC for the reference picture 630 of the reference PU 610 are different, the prediction unit scales the REF, that is, mvIL, and includes it in the AMVP. You can.

mvIL may be scaled in the same manner as in Equation 3. The scaled mvIL is called mvIL '.

<Equation 3>

tx = (16384 + (Abs (td) >> 1)) / td

DistScaleFactor = Clip3 (? 4096, 4095, (tb * tx + 32) >> 6)

mvIL ’= Clip3 (? 8192, 8191.75, Sign (DistScaleFactor * mvIL) *

((Abs (DistScaleFactor * mvIL) + 127) >> 8))

td = Clip3 (? 128, 127, pocCurr? pocRefLayer)

tb = Clip3 (? 128, 127, pocCurr? pocRef)

In Equation 3, pocCurr represents the POC of the current picture, pocRef is the POC of the picture indicated by the reference index of the current PU, and pocRefLayer is indicated by the reference index of the reference PU, that is, the reference index of (xRef, yRef). POC of the picture.

Abs (x) becomes? X when x is smaller than 0, and x when x is greater than or equal to 0. Clip3 (x, y.c) becomes x when z is smaller than x, y when z is larger than y, and z otherwise.

When the pocRef and pocRefLayer are different, the prediction unit scales the interlayer motion vector based on the distance from each layer to the reference picture, as shown in Equation 3, and scales the scaled motion vector candidate (ie, scaled mvIL or scaled REF). Can be added to AMVP list.

In this case, the prediction unit may include the scaled REF (ie, scaled mvIL) in the AMVP list instead of the REF (ie, mvIL), and perform interlayer motion prediction using the AMVP mode in the same manner as described above.

In case of applying inter-layer motion prediction, all CU partitions can be used as they are regardless of the block size of the base layer from the perspective of the CU level. In addition, at the PU level, the encoding apparatus may apply an optimal prediction mode by performing RDO for inter prediction and inter-layer motion prediction.

Hereinafter, the determination of the redundancy of the motion information of the reference layer and the motion information of the current layer in inter-layer inter prediction according to the present invention will be described in more detail.

As described in Tables 1 and 3, when the motion information of the reference layer is not available or the reference PU is predicted to intra mode, the candidate candidates are derived when deriving the merge candidate list or the AMVP list without referring to the reference layer. The method of determining redundancy may be applied to determining redundancy of motion information of the current layer.

On the other hand, when using the REF derived from the reference layer, the prediction unit may configure the merge candidate list as shown in Table 5, and may determine the redundancy of the candidates along with the usefulness determination when constructing the merge candidate list.

Table 5

As shown in Table 5, the index of the smallest value is assigned to the REF derived from the reference layer. That is, the prediction unit sets REF as the first candidate of the merge candidate list without performing a separate redundancy determination. In this case, since the redundancy determination is not performed with the other merge candidates with respect to the REF, independence with the other merge candidates can be maintained. If the independence of REF is maintained, there is an advantage that a merge candidate list can be derived in parallel.

Alternatively, when the REF of the reference layer is used, the prediction unit may configure the merge candidate list as shown in Table 6, and may determine the redundancy of the candidates along with the usefulness determination in constructing the merge candidate list.

Table 6

According to Table 6, redundancy with REF is determined for all merge candidates other than REF. In this case, since the redundancy of each of the spatial candidates and COLs derived from the current layer and REF is checked, candidates identical to REFs among A1, B1, B0, A0, B2 and COL are not added to the merge candidate list.

Alternatively, the prediction unit may determine a redundancy of the REF only for some of the candidates other than the REF by combining a method of not determining the redundancy of the REF and all the candidates and a method of determining the redundancy of the REF and all the candidates.

For example, the prediction unit may perform redundancy determination on only some predetermined candidates as shown in Tables 7 and 8 and add candidates that do not overlap with the REF to the merge candidate list.

TABLE 7

Referring to Table 7, the prediction unit determines the redundancy with the REF only for the remaining A1, B1, B0, A0, and B2 without determining the redundancy with the REF for the COL.

Table 8

Referring to Table 8, the prediction unit may determine redundancy with REF when adding A1 and B1 to the candidate list, and may omit redundancy determination for the remaining candidates B0, A0, B2, and COL.

As described above, when the redundancy of the limited number of some candidates and the REF is determined instead of all candidates, the complexity of the redundancy determination can be reduced.

In this case, the merge candidate determined to be redundant with the REF is not limited to A1 and B1 and may be changed to another candidate. Candidates that are subject to redundancy judgment may be set as candidates that have the greatest influence on complexity reduction based on the experimental results. In addition, the number of candidates for which redundancy determination with REF is omitted may also be changed to another number, which may also be set based on experimental values.

According to another exemplary embodiment, the prediction unit may allocate REF to the middle or last index of the merge candidate list rather than the smallest index among the merge candidate lists. In this case, the prediction unit may determine the redundancy of all previous merge candidates and the REF, or may determine the redundancy of the specific some candidates and the REF. Table 9 shows the case where REF is added to the merge list after A1, B1, B0, A0, and B2.

Table 9

Referring to Table 9, the prediction unit determines candidate validity and redundancy in the order of A1, B1, B0, A0, and B2, adds A1, B1, B0, A0, and B2 to the merge candidate list according to the determination result, and then REF Can be added to the candidate list. In this case, REF may be determined to be redundant with A1 and B1 among A1, B1, B0, A0, and B2. That is, REF may be added to the candidate list only if it is different from A1 and different from B1.

Alternatively, according to another exemplary embodiment, the prediction unit may further determine whether REF and B2 are redundant in addition to A1 and B1, and may add the candidate to the candidate list when REF does not overlap with B2.

According to another embodiment, two or more REFs instead of one may be included in the merge candidate list. For example, REF is expressed as ⑧ RB '= (xP + nPSW, yP + nPSH) and ⑫ C3 = (xP + (nPSW >> 1), yP + (nPSH >> 1)) mentioned in the description of FIG. It may be motion information of a PU specified by a location. Hereinafter, for convenience of description, the motion information of the reference PU specified at the 8 position of the reference layer is referred to as REF 1, and the motion information of the reference PU specified to the X position of the reference layer is referred to as REF 2. In this case, redundancy may also be determined between REF 1 and REF 2 of two reference PUs. Table 10 shows a merge candidate list including REF 1 and REF 2.

Table 10

Referring to Table 10, the prediction unit may determine the redundancy with REF 1 when adding REF 1 to the first merge candidate list and adding A1 and B1 to the candidate list. In addition, the prediction unit may determine the validity of the REF 2 after determining the validity of the spatial merge candidates A1, B1, B0, A0, and B2, and may determine the redundancy of the REF 1 and the REF 2.

According to another embodiment, REF 2 may be added to the merge candidate list in a different order from Table 10, for example, may be added to the end of the merge candidate list. Even in this case, when REF 2 is added to the merge candidate list, redundancy with REF 1 may be determined.

On the other hand, the prediction unit may configure the AMVP list of inter-layer motion prediction as shown in Table 11, and may determine the redundancy of the candidates along with the determination of the usefulness of the candidate when constructing the AMVP list.

Table 11

As shown in Table 11, the index of the smallest value is assigned to the REF derived from the reference layer. That is, the prediction unit sets REF as the first candidate of the AMVP list without performing a separate redundancy determination. In this case, since the redundancy determination is not performed with the other merge candidates with respect to the REF, independence with other AMVP candidates can be maintained. If the independence of REF is maintained, there is an advantage of deriving AMVP lists in parallel.

Alternatively, when the REF of the reference layer is used, the prediction unit may configure the AMVP list as shown in Table 12. When the AMVP list is constructed, the prediction unit may determine the redundancy of candidates along with the usefulness determination.

Table 12

According to Table 12, for all AMVP candidates other than REF, redundancy with REF is determined. In this case, since the redundancy of each of the AMVP candidate, COL, and zero motion vectors derived from the current layer and REF is checked, the same candidate as REF will not be added to the AMVP list.

Alternatively, the prediction unit may determine a redundancy with the REF only for some of the candidates other than the REF by combining a method of not determining the redundancy of the REF and all the candidates and a method of determining the redundancy of the REF and all the candidates.

For example, the prediction unit may perform redundancy determination on only some predetermined candidates as shown in Tables 13 and 14, and add candidates that do not overlap with the REF to the AMVP list.

Table 13

Referring to Table 13, the prediction unit determines the redundancy with the REF only for the remaining A and B, without determining the redundancy with the REF for the COL and the zero motion vector candidates.

Table 14

Referring to Table 14, the prediction unit may determine redundancy with the REF only when A, B1, and COL are added to the AMVP list, and omit the redundancy determination with respect to the zero motion vector candidate.

As described above, when the redundancy of the limited number of some candidates and the REF is determined instead of all candidates, the complexity of the redundancy determination can be reduced.

According to another embodiment, the prediction unit may determine the redundancy of either REF or AREF.

As described above, candidates to be subjected to redundancy determination may be set as candidates having the greatest influence on complexity reduction based on the experimental results. In addition, the number of candidates for which redundancy determination with REF is omitted may also be set based on experimental values.

According to another exemplary embodiment, the predictor may allocate REF to the middle or last index of the AMVP list rather than the smallest index among the AMVP lists. In this case, the prediction unit may determine the redundancy of all previous merge candidates and the REF, or may determine the redundancy of the specific some candidates and the REF. Table 15 shows the case where REF is added to the AMVP list after A and B.

Table 15

Referring to Table 15, the prediction unit may determine candidate validity and redundancy in the order of A and B, add A and B to the AMVP list according to the determination result, and then add REF to the candidate list. In this case, REF may be determined to be redundant with A and B. That is, REF is different from A and can be added to the AMVP list only if it is different from B.

Alternatively, according to another embodiment, the prediction unit may determine the redundancy of the REF with either A or B.

Alternatively, the prediction unit may add the REF to the AMVP list after the COL. In this case, redundancy with all of A, B, and COL may be determined, or redundancy with some candidates may be determined.

7 is a control flowchart illustrating a method of decoding an image according to an embodiment of the present invention.

Referring to FIG. 7, the predictor first configures a motion prediction list by determining whether at least one of motion information of a neighboring block of a current block and motion information of a COL block is overlapped with a reference block (S701).

The motion prediction list may include inter-layer inter prediction for the current block, that is, a merge candidate list for inter-layer motion prediction or a list for the motion vector predictor, that is, an AMVP list.

If the motion prediction list is a merge candidate list, the motion information may be a motion vector and a reference index, and if the motion prediction list is an AMVP list, the motion information may be information about the motion vector.

The predictor includes a motion prediction list based on the motion information of adjacent neighboring blocks of the current block, the motion information of the COL block corresponding to the current block in the corresponding picture of the current block, and the motion information of the reference block of the reference layer corresponding to the current block. Configure

The motion information for the neighboring block may be B, which is motion information selected from among the motion information A, B1, B0, and B2 selected from A1, B1, B0, A0, B2, A1 and A0 of FIG. 5, and the motion for the neighboring block. The information may be included in at least one list.

The predictor determines whether at least one of the motion information of the neighboring block and the motion information of the COL block is overlapped with the reference block when constructing the motion prediction list. Such redundancy determination may be included in the process of determining the validity of the motion information when the motion information is added to the motion prediction list.

The prediction unit adds, to the motion prediction list, only motion information that is not the same as the motion information of the reference block that does not overlap with the motion information of the reference block. Hereinafter, the method will be described in more detail with reference to FIG. 8.

Thereafter, inter prediction on the current block is performed based on the motion prediction list (S702).

If the motion prediction list is a merge candidate list, the decoding apparatus receives a merge index and residual information of the current block for which candidate from the merge candidate list to use. The decoding apparatus derives the prediction block for the current block based on the received merge index information, and adds the received residual information to the prediction block to restore the current block.

If the motion prediction list is an AMVP list, the decoding apparatus receives a reference index for a reference picture, difference information for a motion vector, flag information for an MVP candidate, and residual information of a current block from an encoding device. The decoding apparatus derives a motion vector for the current block based on the difference information for the motion vector and the motion vector predictor, and generates a predictive block for the current block using the reference picture. The current block is reconstructed by the addition of the received residual information and the prediction block.

8 is a control flowchart illustrating a method of constructing a motion candidate list according to an embodiment of the present invention.

Referring to FIG. 8, the predictor sets motion information of a reference block as a candidate of a motion prediction list (S801). The motion information of the reference block may be assigned the lowest index of the motion prediction list.

After adding the motion information of the reference block to the motion prediction list, the prediction unit determines the redundancy of the motion information of the reference block and the predetermined motion information among the motion information of the neighboring blocks of the current block which is spatial motion information (S802).

The spatial motion information to be added to the motion prediction list may be at least one.

If the motion prediction list is a merge candidate list, the prediction unit may determine validity in order of spatial motion information A1, B1, B0, A0, and B2, and may determine the motion information and redundancy of the reference block with respect to A1 and B1 when determining the validity. .

Of course, the prediction unit is not limited to A1 and B1, and may determine redundancy between other motion information and motion information of the reference block.

If the motion prediction list is an AMVP list, the prediction unit judges the validity of the motion information A selected from A1 and A0 and B, which is motion information selected from B1, B0, and B2, and when determining the validity, both A and B or A and B It is possible to determine the motion information and redundancy of one of the and the reference block.

The prediction unit may also determine the redundancy of the motion information of the COL block and the motion information of the reference block (S803).

Thereafter, the prediction unit may set motion information that is not the same as motion information of the reference block as a candidate of the motion prediction list (S804).

That is, the prediction unit adds motion information of the neighboring block that is not the same as motion information of the reference block as a candidate of the motion prediction list, and if the motion information of the COL block and the motion information of the reference block are not the same, the motion information of the COL block. Is added to the candidate of the motion prediction list. This step may be performed after step S802 and after step S803, respectively.

Steps S802 and S803 may be both performed by the prediction unit, or only one of them may be performed.

According to another embodiment of the present invention, the prediction unit adds the motion information of the at least one neighboring block and / or the motion information of the COL block as a candidate of the motion prediction list, and then adds the motion information of the reference block to the motion prediction list. can do.

In this case, in the process of determining the validity of the motion information of the reference block, the prediction unit may determine whether or not it is identical to at least one of the motion information already added to the motion prediction list.

The prediction unit may determine the redundancy of the predetermined number of predetermined motion information candidates and the motion information of the reference block. The preset number of predetermined motion information candidates may be set by an experimental value.

Alternatively, the prediction unit may determine whether or not the motion information of the reference block is duplicated with all motion information added to or to be added to the motion prediction list.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, since the above-described embodiments may include examples of various aspects, a combination of each embodiment should also be understood as an embodiment of the present invention. Accordingly, the invention is intended to embrace all other replacements, modifications and variations that fall within the scope of the following claims.

Claims (16)

1. A motion prediction list based on motion information of adjacent neighboring blocks of a current block, motion information of a COL block corresponding to the current block within a corresponding picture of the current block, and motion information of a reference block of a reference layer corresponding to the current block Configuring the;

   Performing inter prediction of the current block based on the motion prediction list,

   The step of constructing the motion prediction list may include determining whether or not there is redundancy between at least one of the motion information of the neighboring block and the motion information of the COL block and the motion information of the reference block. Way.
2. The method of claim 1,

   Comprising the motion prediction list,

   Setting motion information of the reference block as a candidate of the motion prediction list;

   Determining a redundancy of predetermined motion information among the motion information of at least one neighboring block and motion information of the reference block;

   And determining the motion information of the neighboring block that is not the same as the motion information of the reference block as a candidate of the motion prediction list.
3. The method of claim 1,

   The motion list is a merge candidate list of the current block,

   Comprising the motion list,

   The lowermost block among the neighboring blocks adjacent to the left side of the current block, the uppermost block among the neighboring blocks adjacent to the upper side of the current block, the upper right corner block of the current block, the lower left corner block of the current block, Determining the validity in order of the upper left corner block of the current block,

   In the determining of the validity, the redundancy of the motion information of the block located at the bottom of the neighboring blocks adjacent to the left side of the current block and the block located at the rightmost side of the neighboring blocks adjacent to the top of the current block and the motion information of the reference block are determined. The image decoding method, characterized in that for determining.
4. The method of claim 1,

   The motion list is a motion vector predictor list of the current block,

   Comprising the motion list,

   First motion information selected from a lowermost corner block among the lower left corner block of the current block and a neighboring block adjacent to the left side of the current block, an upper right corner block of the current block, and a neighboring block adjacent to the top of the current block; Determining the validity of the second motion information selected from the block located on the right side and the upper left corner block of the current block;

   And determining the redundancy of at least one of the first motion information and the first motion information and the motion information of the reference block when determining the validity.
5. The method of claim 1,

   Comprising the motion prediction list,

   Setting motion information of the reference block as a candidate of the motion prediction list;

   Determining a redundancy of motion information of the COL block and motion information of the reference block;

   And determining the motion information of the COL block as a candidate of the motion prediction list if the motion information of the COL block and the motion information of the reference block are not the same.
6. The method of claim 1,

   Comprising the motion list,

   Setting motion information of at least one neighboring block as a candidate of the motion prediction list;

   Determining a redundancy of predetermined motion information among the motion information of the at least one neighboring block and motion information of the reference block;

   And if the predetermined motion information and the motion information of the reference block are not the same, setting the motion information of the reference block as a candidate of the motion prediction list.
7. The method of claim 1,

   Comprising the motion prediction list,

   Setting motion information of the COL block as a candidate of the motion prediction list;

   Determining a redundancy of the motion information of the reference block and the motion information of the COL block;

   And determining that the motion information of the reference block is the same as a candidate of the motion prediction list if the motion information of the reference block and the motion information of the COL block are not the same. .
8. The method of claim 1,

   And determining whether or not both the motion information of the neighboring block and the motion information of the reference block overlap with the reference block.
9. A motion prediction list based on motion information of adjacent neighboring blocks of a current block, motion information of a COL block corresponding to the current block within a corresponding picture of the current block, and motion information of a reference block of a reference layer corresponding to the current block A predicting unit configured to perform an inter prediction on the current block based on the motion prediction list,

   And the prediction unit determines whether or not there is overlap between the motion information of the neighboring block and the motion information of the COL block and the motion information of the reference block.
10. The method of claim 9,

    The prediction unit sets the motion information of the reference block as a candidate of the motion prediction list, and determines the redundancy of the motion information of the reference block and the predetermined motion information among the motion information of at least one neighboring block.

    And as a result of the determination, motion information of the neighboring block that is not identical to motion information of the reference block is set as a candidate of the motion prediction list.
11. The method of claim 9,

    The motion list is a merge candidate list of the current block,

    The prediction unit is located at the bottom of the neighboring block adjacent to the left side of the current block, the block located at the rightmost side of the neighboring block adjacent to the top of the current block, the upper right corner block of the current block, the lower left corner of the current block Block, and then the validity is determined in order of the upper left corner block of the current block,

    In determining the validity, the redundancy of the motion information of the block located at the bottom of the neighboring blocks adjacent to the left side of the current block and the block located at the rightmost side of the neighboring blocks adjacent to the top of the current block and the motion information of the reference block are determined. An apparatus for decoding an image, characterized in that.
12. The method of claim 9,

    The motion list is a motion vector predictor list of the current block,

    The prediction unit may include first motion information selected from a lowermost corner block among a lower left corner block of the current block and a neighboring block adjacent to a left side of the current block, an upper right corner block of the current block, and a top of the current block. Determining the validity of the second motion information selected from the rightmost block among the neighboring blocks and the upper left corner block of the current block;

    And determining the redundancy of at least one of the first motion information and the first motion information and the motion information of the reference block when determining the validity.
13. The method of claim 9,

    The prediction unit sets the motion information of the reference block as a candidate of the motion prediction list, and determines the redundancy of the motion information of the COL block and the motion information of the reference block.

    And determining that the motion information of the COL block is the same as a candidate of the motion prediction list if the motion information of the COL block and the reference block are not the same.
14. The method of claim 9,

    The prediction unit sets the motion information of at least one neighboring block as a candidate of the motion prediction list, and determines the redundancy of the motion information of the reference block and the predetermined motion information among the motion information of the at least one neighboring block. ,

    And the motion information of the reference block is set as a candidate of the motion prediction list if the predetermined motion information and the motion information of the reference block are not the same.
15. The method of claim 9,

    The prediction unit sets the motion information of the COL block as a candidate of the motion prediction list, and determines the redundancy of the motion information of the reference block and the motion information of the COL block,

    And if the motion information of the reference block and the motion information of the COL block are not the same, the motion information of the reference block is set as a candidate of the motion prediction list.
16. The method of claim 9,

    And the prediction unit determines whether or not both the motion information of the neighboring block and the motion information of the reference block overlap with the reference block.

Images