WO2020005002A1

WO2020005002A1 - Method and device for deriving template area according to inter-prediction in image coding system

Info

Publication number: WO2020005002A1
Application number: PCT/KR2019/007872
Authority: WO
Inventors: 박내리; 남정학; 이재호; 장형문
Original assignee: 엘지전자 주식회사
Priority date: 2018-06-28
Filing date: 2019-06-28
Publication date: 2020-01-02

Abstract

A method by which a decoding device decodes an image, according to the present invention, comprises the steps of: deriving a merge index of a current block; constructing a merge candidate list of the current block; deriving a template area adjacent to the current block; rearranging the merge candidate list on the basis of the template area; and generating a predicted block for the current block on the basis of the merge index and the merge candidate list, wherein the template area includes, from among a left peripheral area and an upper peripheral area adjacent to the current block, an area not included in a previous block to be restored immediately before the current block.

Description

Method and apparatus for deriving template region according to inter prediction in image coding system

The present invention relates to image coding technology, and more particularly, to a method and apparatus for deriving a template region according to inter prediction in an image coding system.

Recently, the demand for high resolution and high quality images such as high definition (HD) images and ultra high definition (UHD) images is increasing in various fields. The higher the resolution and the higher quality of the image data, the more information or bit rate is transmitted than the existing image data. Therefore, the image data can be transmitted by using a medium such as a conventional wired / wireless broadband line or by using a conventional storage medium. In the case of storage, the transmission cost and the storage cost are increased.

Accordingly, a high efficiency image compression technique is required to effectively transmit, store, and reproduce high resolution, high quality image information.

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

Another object of the present invention is to provide a method and apparatus for removing a pipeline delay when a template matching method is used in a process of refining a motion vector during decoding.

Another technical problem of the present invention is to provide a method and apparatus for adaptively deriving a template region in order to eliminate pipeline delay.

Another technical problem of the present invention is to provide a method and apparatus for grouping candidates in consideration of memory bandwidth.

According to an embodiment of the present invention, there is provided an image decoding method performed by a decoding apparatus. The method includes deriving a merge index of a current block, constructing a merge candidate list of the current block, deriving a template region adjacent to the current block, and rearranging the merge candidate list based on the template region. And generating a predicted block for the current block based on the merge index and the merge candidate list, wherein the template region includes a region of the current block among a left peripheral region and an upper peripheral region adjacent to the current block. And a region not included in the previous block to be restored immediately before.

According to another embodiment of the present invention, a decoding apparatus for performing image decoding is provided. The decoding apparatus derives an entropy decoding unit for obtaining prediction information about a current block and a merge index of the current block, constructs a merge candidate list of the current block, derives a template region adjacent to the current block, and generates the template. Reordering the merge candidate list based on a region, and generating a predicted block for the current block based on the merge index and the merge candidate list, wherein the template region includes a left periphery adjacent to the current block. And an area not included in a previous block restored immediately before the current block among an area and an upper peripheral area.

According to another embodiment of the present invention, a video encoding method performed by an encoding apparatus is provided. The method includes constructing a merge candidate list of a current block, deriving a template region adjacent to the current block, rearranging the merge candidate list based on the template region, and deriving a merge index of the current block. Generating a predicted block for the current block based on the merge index and the merge candidate list, and generating, encoding, and outputting predictive information about the current block, wherein the template region includes: And a region not included in the previous block restored immediately before the current block among the left peripheral region and the upper peripheral region adjacent to the current block.

According to another embodiment of the present invention, a video encoding apparatus is provided. The encoding apparatus constructs a merge candidate list of the current block, derives a template region adjacent to the current block, rearranges the merge candidate list based on the template region, derives a merge index of the current block, A predictor for generating a predicted block for the current block based on a merge index and the merge candidate list, and an entropy encoding unit for generating, encoding, and outputting predictive information about the current block, wherein the template region includes: And a region not included in the previous block to be restored immediately before the current block among the left peripheral region and the upper peripheral region adjacent to the block.

According to the present invention, motion information can be derived from a neighboring block and refined the derived motion information to increase the accuracy of motion prediction.

According to the present invention, the process of refining a motion vector during decoding can be improved to be friendly to hardware to increase the utilization, thereby improving coding efficiency.

1 is a diagram schematically illustrating a configuration of a video encoding apparatus to which the present invention may be applied.

2 is a diagram schematically illustrating a configuration of a video decoding apparatus to which the present invention may be applied.

3 schematically illustrates an example of pipeline delay occurrence.

4 illustrates an example in which a block is divided into quadtrees.

5 shows an example in which a block is divided into a binary tree and a ternary tree and the direction is horizontal.

6 shows an example in which a block is divided into a binary tree and a ternary tree and the direction is vertical.

7 schematically illustrates an example of a decoding process for determining a template region to apply to a current block.

8 schematically illustrates an example of a simplified decoding process of determining a template region to be applied to a current block.

9A and 9B show an example of expansion of a template area when a block is divided into ternary trees and the direction is vertical.

10 schematically shows an example of a decoding process for extending a template region to apply to a current block.

11A and 11B illustrate examples of template regions to be applied to a current block according to split information of a previous block.

12 schematically illustrates an example of a decoding process of determining a template to apply to a current block according to partition information of a previous block.

13 shows an example of a decoding process of grouping MVP candidate lists and determining a template region.

14 illustrates an example of a decoding process in which a refinement process is added to FIG. 13.

15 schematically illustrates an image encoding method by an encoding apparatus according to the present invention.

16 schematically illustrates an image decoding method by a decoding apparatus according to the present invention.

17 schematically illustrates a content streaming system structure.

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. The terms "comprise" or "having" in this specification are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features It is to be understood that the numbers, steps, operations, components, parts or figures do not exclude in advance the presence or possibility of adding them.

On the other hand, each configuration in the drawings described in the present invention are shown independently for the convenience of description of the different characteristic functions, it does not mean that each configuration is implemented by separate hardware or separate software. 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.

The video / picture coding system can include a source device and a receiving device. The source device may deliver the encoded video / image information or data to the receiving device via a digital storage medium or network in the form of a file or streaming.

The source device may include a video source, an encoding apparatus, and a transmitter. The receiving device may include a receiving unit, a decoding apparatus, and a renderer. The encoding device may be called a video / image encoding device, and the decoding device may be called a video / image decoding device. The transmitter may be included in the encoding device. The receiver may be included in the decoding device. The renderer may include a display unit, and the display unit may be configured as a separate device or an external component.

The video source may acquire the video / image through a process of capturing, synthesizing, or generating the video / image. The video source may comprise a video / image capture device and / or a video / image generation device. The video / image capture device may include, for example, one or more cameras, video / image archives including previously captured video / images, and the like. Video / image generation devices may include, for example, computers, tablets and smartphones, and may (electronically) generate video / images. For example, a virtual video / image may be generated through a computer or the like. In this case, the video / image capturing process may be replaced by a process of generating related data.

The encoding device may encode the input video / image. The encoding apparatus may perform a series of procedures such as prediction, transform, and quantization for compression and coding efficiency. The encoded data (encoded video / image information) may be output in the form of a bitstream.

The transmitter may transmit the encoded video / video information or data output in the form of a bitstream to the receiver of the receiving device through a digital storage medium or a network in the form of a file or streaming. The digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and the like. The transmission unit may include an element for generating a media file through a predetermined file format, and may include an element for transmission through a broadcast / communication network. The receiver may receive / extract the bitstream and transmit the received bitstream to the decoding apparatus.

The decoding apparatus may decode the video / image by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to the operation of the encoding apparatus.

The renderer may render the decoded video / image. The rendered video / image may be displayed through the display unit.

The present invention relates to video / picture coding. For example, the methods / embodiments disclosed in the present invention may include a versatile video coding (VVC) standard, an essential video coding (EVC) standard, an AOMedia Video 1 (AV1) standard, a second generation of audio video coding standard (AVS2) or a next generation video / It can be applied to the method disclosed in the image coding standard (eg H.267 or H.268, etc.).

In the present invention, various embodiments related to video / image coding are presented, and unless otherwise stated, the above embodiments may be performed in combination with each other.

In the present invention, video may refer to a series of images over time. A picture generally refers to a unit representing one image in a specific time zone, and a slice / tile is a unit constituting part of a picture in coding. The slice / tile may comprise one or more coding tree units (CTUs). One picture may consist of one or more slices / tiles. One picture may consist of one or more tile groups. One tile group may include one or more tiles. The brick may represent a rectangular region of CTU rows within a tile in the picture.

In the present invention, tile groups and slices may be used interchangeably. For example, in this document, tile group / tile group header may be called slice / slice header.

A pixel or a pel may refer to a minimum unit constituting one picture (or image). Also, 'sample' may be used as a term corresponding to a pixel. A sample may generally represent a pixel or a value of a pixel, and may represent only a pixel / pixel value of a luma component or only a pixel / pixel value of a chroma component.

A unit may represent a basic unit of image processing. The unit may include at least one of a specific region of the picture and information related to the region. One unit may include one luma block and two chroma (ex. Cb, cr) blocks. The unit may be used interchangeably with terms such as block or area in some cases. In a general case, an M × N block may comprise a sample (or sample array) or a set (or array) of transform coefficients of M columns and N rows.

In the present invention, "/" and "," are interpreted as "and / or". For example, "A / B" is interpreted as "A and / or B" and "A, B" is interpreted as "A and / or B". In addition, "A / B / C" means "at least one of A, B and / or C". In addition, "A, B, C" also means "at least one of A, B and / or C."

In addition, in this document "or" is interpreted as "and / or". For example, "A or B" may mean 1) "A" only, 2) "B" only, or 3) "A and B". In other words, "or" in this document may mean "additionally or alternatively".

Referring to FIG. 1, the encoding apparatus 100 may include an image splitter 110, a subtractor 115, a transformer 120, a quantizer 130, an inverse quantizer 140, an inverse transformer 150, The adder 155, the filter 160, the memory 170, the inter predictor 180, the intra predictor 185, and the entropy encoder 190 may be configured. The inter predictor 180 and the intra predictor 185 may be collectively called a predictor. That is, the predictor may include an inter predictor 180 and an intra predictor 185. The transform unit 120, the quantization unit 130, the inverse quantization unit 140, and the inverse transform unit 150 may be included in the residual processing unit. The residual processing unit may further include a subtracting unit 115. The image divider 110, the subtractor 115, the transformer 120, the quantizer 130, the inverse quantizer 140, the inverse transformer 150, the adder 155, and the filter 160 are described above. ), The inter predictor 180, the intra predictor 185, and the entropy encoder 190 may be configured by one hardware component (eg, an encoder chipset or a processor) according to an embodiment. In addition, the memory 170 may include a decoded picture buffer (DPB) or may be configured by a digital storage medium. The hardware component may further include the memory 170 as an internal / external component.

The image divider 110 may divide the input image (or picture or frame) input to the encoding apparatus 100 into one or more processing units. For example, the processing unit may be called a coding unit (CU). In this case, the coding unit may be recursively divided according to a quad-tree binary-tree ternary-tree (QTBTTT) structure from a coding tree unit (CTU) or a largest coding unit (LCU). Can be. For example, one coding unit may be divided into a plurality of coding units of a deeper depth based on a quad tree structure, a binary tree structure, and / or a ternary tree structure. In this case, for example, the quad tree structure may be applied first and the binary tree structure and / or ternary tree structure may be applied later. Alternatively, the binary tree structure may be applied first. The coding procedure according to the present invention may be performed based on the final coding unit that is no longer split. In this case, the maximum coding unit may be used as the final coding unit immediately based on coding efficiency according to the image characteristic, or if necessary, the coding unit is recursively divided into coding units of lower depths and optimized. A coding unit of size may be used as the final coding unit. Here, the coding procedure may include a procedure of prediction, transform, and reconstruction, which will be described later. As another example, the processing unit may further include a prediction unit (PU) or a transform unit (TU). In this case, the prediction unit and the transform unit may be partitioned or partitioned from the aforementioned final coding unit, respectively. The prediction unit may be a unit of sample prediction, and the transformation unit may be a unit for deriving a transform coefficient and / or a unit for deriving a residual signal from the transform coefficient.

The unit may be used interchangeably with terms such as block or area in some cases. In a general case, an M × N block may represent a set of samples or transform coefficients composed of M columns and N rows. A sample may generally represent a pixel or a value of a pixel, and may only represent pixel / pixel values of the luma component, or only pixel / pixel values of the chroma component. A sample may be used as a term corresponding to one picture (or image) for a pixel or a pel.

The encoding apparatus 100 subtracts the prediction signal (predicted block, prediction sample array) output from the inter prediction unit 180 or the intra prediction unit 185 from the input image signal (original block, original sample array). A signal may be generated (residual signal, residual block, residual sample array), and the generated residual signal is transmitted to the converter 120. In this case, as shown, a unit that subtracts a prediction signal (prediction block, prediction sample array) from an input image signal (original block, original sample array) in the encoder 100 may be called a subtraction unit 115. The prediction unit may perform a prediction on a block to be processed (hereinafter, referred to as a current block) and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is applied on a current block or CU basis. As described later in the description of each prediction mode, the prediction unit may generate various information related to prediction, such as prediction mode information, and transmit the generated information to the entropy encoding unit 190. The information about the prediction may be encoded in the entropy encoding unit 190 and output in the form of a bitstream.

The intra predictor 185 may predict the current block by referring to the samples in the current picture. The referenced samples may be located in the neighborhood of the current block or may be located apart according to the prediction mode. In intra prediction, prediction modes may include a plurality of non-directional modes and a plurality of directional modes. Non-directional mode may include, for example, DC mode and planner mode (Planar mode). The directional mode may include, for example, 33 directional prediction modes or 65 directional prediction modes according to the degree of detail of the prediction direction. However, as an example, more or less directional prediction modes may be used depending on the setting. The intra predictor 185 may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring block.

The inter predictor 180 may derive the predicted block with respect to the current block based on the reference block (reference sample array) specified by the motion vector on the reference picture. In this case, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information may be predicted in units of blocks, subblocks, or samples based on the correlation of the motion information between the neighboring block and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter prediction, the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block present in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different. The temporal neighboring block may be referred to as a collocated reference block, a collocated CU (colCU), and the like, and a reference picture including the temporal neighboring block is called a collocated picture (colPic). It may be. For example, the inter prediction unit 180 constructs a motion information candidate list based on neighboring blocks and provides information indicating which candidates are used to derive a motion vector and / or a reference picture index of the current block. Can be generated. Inter prediction may be performed based on various prediction modes. For example, in case of a skip mode and a merge mode, the inter prediction unit 180 may use motion information of a neighboring block as motion information of a current block. In the skip mode, unlike the merge mode, the residual signal may not be transmitted. In the motion vector prediction (MVP) mode, the motion vector of the neighboring block is used as a motion vector predictor and the motion vector difference is signaled by signaling a motion vector difference. Can be directed.

The prediction unit may generate a prediction signal based on various prediction methods described below. For example, the prediction unit may not only apply intra prediction or inter prediction to predict one block but also simultaneously apply intra prediction and inter prediction. This may be called combined inter and intra prediction (CIIP). In addition, the prediction unit may perform intra block copy (IBC) to predict a block. The intra block copy may be used for content video / video coding of a game or the like, for example, screen content coding (SCC). The IBC basically performs prediction in the current picture but may be performed similarly to inter prediction in that a reference block is derived in the current picture. That is, the IBC can use at least one of the inter prediction techniques described in this document.

The prediction signal generated by the prediction unit (including the inter prediction unit 180 and / or the intra prediction unit 185) may be used to generate a reconstruction signal or to generate a residual signal. The transformer 120 may apply transform techniques to the residual signal to generate transform coefficients. For example, the transformation technique may be a discrete cosine transform (DCT), a discrete sine transform (DST), a karhunen-lo *? * Ve transform (KLT), a graph-based transform (GBT), or a conditionally non-linear transform (CNT). It may include at least one of. Here, GBT means a conversion obtained from this graph when the relationship information between pixels is represented by a graph. CNT refers to a transform that is generated based on and generates a prediction signal using all previously reconstructed pixels. In addition, the conversion process may be applied to pixel blocks having the same size as the square, or may be applied to blocks of variable size rather than square.

The quantization unit 130 quantizes the transform coefficients and transmits them to the entropy encoding unit 190. The entropy encoding unit 190 encodes the quantized signal (information about the quantized transform coefficients) and outputs the bitstream. have. The information about the quantized transform coefficients may be referred to as residual information. The quantization unit 130 may rearrange block quantized transform coefficients into a one-dimensional vector form based on a coefficient scan order, and quantize the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form. Information about transform coefficients may be generated. The entropy encoding unit 190 may perform various encoding methods such as, for example, exponential Golomb, context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC), and the like. The entropy encoding unit 190 may encode information necessary for video / image reconstruction other than quantized transform coefficients (for example, values of syntax elements) together or separately. Encoded information (eg, encoded video / image information) may be transmitted or stored in units of NALs (network abstraction layer) in the form of a bitstream. The video / image information may further include information about various parameter sets such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may further include general constraint information. Signaling / transmitted information and / or syntax elements described later in this document may be encoded and included in the bitstream through the above-described encoding procedure. The bitstream may be transmitted over a network or may be stored in a digital storage medium. The network may include a broadcasting network and / or a communication network, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and the like. The signal output from the entropy encoding unit 190 may include a transmitting unit (not shown) for transmitting and / or a storing unit (not shown) for storing as an internal / external element of the encoding apparatus 100, or the transmitting unit It may be included in the entropy encoding unit 190.

The quantized transform coefficients output from the quantization unit 130 may be used to generate a prediction signal. For example, the inverse quantization and inverse transform may be applied to the quantized transform coefficients through the inverse quantization unit 140 and the inverse transform unit 150 to restore the residual signal (residual block or residual samples). The adder 155 adds the reconstructed residual signal to the predicted signal output from the inter predictor 180 or the intra predictor 185 so that a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) is added. Can be generated. If there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as the reconstructed block. The adder 155 may be called a restoration unit or a restoration block generation unit. The generated reconstruction signal may be used for intra prediction of a next processing target block in a current picture, and may be used for inter prediction of a next picture through filtering as described below.

Meanwhile, luma mapping with chroma scaling (LMCS) may be applied during picture encoding and / or reconstruction.

The filtering unit 160 may improve subjective / objective image quality by applying filtering to the reconstruction signal. For example, the filtering unit 160 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and the modified reconstructed picture is stored in the memory 170, specifically, the DPB of the memory 170. Can be stored in The various filtering methods may include, for example, deblocking filtering, a sample adaptive offset, an adaptive loop filter, a bilateral filter, and the like. As described below in the description of each filtering method, the filtering unit 160 may generate various information about the filtering and transmit the generated information to the entropy encoding unit 190. The filtering information may be encoded in the entropy encoding unit 190 and output in the form of a bitstream.

The modified reconstructed picture transmitted to the memory 170 may be used as the reference picture in the inter predictor 180. When the inter prediction is applied through the encoding apparatus, the encoding apparatus may avoid prediction mismatch between the encoding apparatus 100 and the decoding apparatus, and may improve encoding efficiency.

The memory 170 DPB may store the modified reconstructed picture for use as a reference picture in the inter predictor 180. The memory 170 may store the motion information of the block from which the motion information in the current picture is derived (or encoded) and / or the motion information of the blocks in the picture that have already been reconstructed. The stored motion information may be transmitted to the inter predictor 180 to use the motion information of the spatial neighboring block or the motion information of the temporal neighboring block. The memory 170 may store reconstructed samples of reconstructed blocks in the current picture, and transfer the reconstructed samples to the intra predictor 185.

Referring to FIG. 2, the decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantizer 220, an inverse transform unit 230, an adder 235, a filter 240, a memory 250, and an inter The prediction unit 260 and the intra prediction unit 265 may be configured. The inter predictor 260 and the intra predictor 265 may be collectively called a predictor. That is, the predictor may include an inter predictor 180 and an intra predictor 185. The inverse quantization unit 220 and the inverse transform unit 230 may be collectively called a residual processing unit. That is, the residual processing unit may include an inverse quantization unit 220 and an inverse transformation unit 230. The entropy decoder 210, the inverse quantizer 220, the inverse transformer 230, the adder 235, the filter 240, the inter predictor 260, and the intra predictor 265 are described in the embodiment. It may be configured by one hardware component (for example, decoder chipset or processor). In addition, the memory 250 may include a decoded picture buffer (DPB) or may be configured by a digital storage medium. The hardware component may further include the memory 250 as an internal / external component.

When a bitstream including video / image information is input, the decoding apparatus 200 may reconstruct an image corresponding to a process in which video / image information is processed in the encoding apparatus of FIG. 1. For example, the decoding apparatus 200 may derive units / blocks based on block division related information obtained from the bitstream. The decoding apparatus 200 may perform decoding using a processing unit applied in the encoding apparatus. Thus, the processing unit of decoding may be a coding unit, for example, and the coding unit may be divided along the quad tree structure, binary tree structure and / or ternary tree structure from the coding tree unit or the largest coding unit. One or more transform units may be derived from the coding unit. The reconstructed video signal decoded and output through the decoding apparatus 200 may be reproduced through the reproducing apparatus.

The decoding apparatus 200 may receive a signal output from the encoding apparatus of FIG. 1 in the form of a bitstream, and the received signal may be decoded through the entropy decoding unit 210. For example, the entropy decoding unit 210 may parse the bitstream to derive information (eg, video / image information) necessary for image reconstruction (or picture reconstruction). The video / image information may further include information about various parameter sets such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may further include general constraint information. The decoding apparatus may further decode the picture based on the information about the parameter set and / or the general restriction information. Signaling / received information and / or syntax elements described later in this document may be decoded through the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit 210 decodes information in a bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, quantized values of syntax elements required for image reconstruction, and transform coefficients for residuals. Can be output. More specifically, the CABAC entropy decoding method receives a bin corresponding to each syntax element in a bitstream, and decodes syntax element information and decoding information of neighboring and decoding target blocks or information of symbols / bins decoded in a previous step. The context model may be determined using the context model, the probability of occurrence of a bin may be predicted according to the determined context model, and arithmetic decoding of the bin may be performed to generate a symbol corresponding to the value of each syntax element. have. In this case, the CABAC entropy decoding method may update the context model by using the information of the decoded symbol / bin for the context model of the next symbol / bean after determining the context model. The information related to the prediction among the information decoded by the entropy decoding unit 210 is provided to a predictor (the inter predictor 260 and the intra predictor 265), and the entropy decoding performed by the entropy decoder 210 is performed. Dual values, that is, quantized transform coefficients and related parameter information, may be input to the inverse quantizer 220. In addition, information on filtering among information decoded by the entropy decoding unit 210 may be provided to the filtering unit 240. Meanwhile, a receiver (not shown) that receives a signal output from the encoding apparatus may be further configured as an internal / external element of the decoding apparatus 200, or the receiver may be a component of the entropy decoding unit 210. Meanwhile, the decoding apparatus according to this document may be referred to as a video / image / picture decoding apparatus, and the decoding apparatus may be divided into an information decoder (video / image / picture information decoder) and a sample decoder (video / image / picture sample decoder). It may be. The information decoder may include the entropy decoding unit 210, and the sample decoder may include the inverse quantization unit 220, an inverse transformer 230, an adder 235, a filter 240, and a memory 250. ), The inter predictor 260, and the intra predictor 265.

The inverse quantization unit 220 may dequantize the quantized transform coefficients and output the transform coefficients. The inverse quantization unit 220 may rearrange the quantized transform coefficients in the form of a two-dimensional block. In this case, the reordering may be performed based on the coefficient scan order performed by the encoding apparatus. The inverse quantization unit 220 may perform inverse quantization on quantized transform coefficients using a quantization parameter (for example, quantization step size information), and may obtain transform coefficients.

The inverse transformer 230 inversely transforms the transform coefficients to obtain a residual signal (residual block, residual sample array).

The prediction unit may perform prediction on the current block and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is applied to the current block based on the information about the prediction output from the entropy decoding unit 210, and may determine a specific intra / inter prediction mode.

The intra predictor 265 may predict the current block by referring to samples in the current picture. The referenced samples may be located in the neighborhood of the current block or may be located apart according to the prediction mode. In intra prediction, prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The intra predictor 265 may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring block.

The inter prediction unit 260 may derive the predicted block for the current block based on the reference block (reference sample array) specified by the motion vector on the reference picture. In this case, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information may be predicted in units of blocks, subblocks, or samples based on the correlation of the motion information between the neighboring block and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter prediction, the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block present in the reference picture. For example, the inter prediction unit 260 may construct a motion information candidate list based on neighboring blocks and derive a motion vector and / or a reference picture index of the current block based on the received candidate selection information. Inter prediction may be performed based on various prediction modes, and the information about the prediction may include information indicating a mode of inter prediction for the current block.

The adder 235 reconstructs the obtained residual signal by adding the obtained residual signal to a predictive signal (predicted block, predictive sample array) output from the predictor (including the inter predictor 260 and / or the intra predictor 265). A signal (restored picture, reconstructed block, reconstructed sample array) can be generated. If there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as the reconstructed block.

The adder 235 may be called a restoration unit or a restoration block generation unit. The generated reconstruction signal may be used for intra prediction of the next block to be processed in the current picture, may be output through filtering as described below, or may be used for inter prediction of the next picture.

Meanwhile, luma mapping with chroma scaling (LMCS) may be applied in the picture decoding process.

The filtering unit 240 may improve subjective / objective image quality by applying filtering to the reconstruction signal. For example, the filtering unit 240 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and the modified reconstructed picture may be stored in the memory 250, specifically, the DPB of the memory 250. Can be sent to. The various filtering methods may include, for example, deblocking filtering, a sample adaptive offset, an adaptive loop filter, a bilateral filter, and the like.

The (modified) reconstructed picture stored in the DPB of the memory 250 may be used as the reference picture in the inter predictor 260. The memory 250 may store the motion information of the block from which the motion information in the current picture is derived (or decoded) and / or the motion information of the blocks in the picture that have already been reconstructed. The stored motion information may be transmitted to the inter predictor 260 to use the motion information of the spatial neighboring block or the motion information of the temporal neighboring block. The memory 250 may store reconstructed samples of reconstructed blocks in the current picture, and transfer the reconstructed samples to the intra predictor 265.

In the present specification, the embodiments described by the filtering unit 160, the inter prediction unit 180, and the intra prediction unit 185 of the encoding apparatus 100 are respectively the filtering unit 240 and the inter prediction of the decoding apparatus 200. The same may also apply to the unit 260 and the intra predictor 265.

The prediction unit of the encoding apparatus / decoding apparatus may derive the prediction sample by performing inter prediction on a block basis. Inter prediction may represent prediction derived in a manner dependent on data elements (e.g. sample values, motion information, etc.) of the picture (s) other than the current picture. When inter prediction is applied to the current block, a predicted block (prediction sample array) for the current block is derived based on a reference block (reference sample array) specified by a motion vector on the reference picture indicated by the reference picture index. Can be. In this case, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information of the current block may be predicted in units of blocks, subblocks, or samples based on the correlation of the motion information between the neighboring block and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include inter prediction type (L0 prediction, L1 prediction, Bi prediction, etc.) information. When inter prediction is applied, the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block present in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different. The temporal neighboring block may be referred to as a collocated reference block, a collocated CU (colCU), and the like, and a reference picture including the temporal neighboring block is called a collocated picture (colPic). It may be. For example, a motion information candidate list may be constructed based on neighboring blocks of the current block, and a flag indicating which candidate is selected (used) to derive a motion vector and / or a reference picture index of the current block. Or index information may be signaled. Inter prediction may be performed based on various prediction modes. For example, in the case of the skip mode and the merge mode, the motion information of the current block may be the same as the motion information of the selected neighboring block. In the skip mode, unlike the merge mode, the residual signal may not be transmitted. In the case of a motion vector prediction (MVP) mode, a motion vector of a selected neighboring block is used as a motion vector predictor, and a motion vector difference may be signaled. In this case, the motion vector of the current block may be derived using the sum of the motion vector predictor and the motion vector difference.

The motion information may include L0 motion information and / or L1 motion information according to an inter prediction type (L0 prediction, L1 prediction, Bi prediction, etc.). The motion vector in the L0 direction may be referred to as an L0 motion vector or MVL0, and the motion vector in the L1 direction may be referred to as an L1 motion vector or MVL1. The prediction based on the L0 motion vector may be called L0 prediction, the prediction based on the L1 motion vector may be called L1 prediction, and the prediction based on both the L0 motion vector and the L1 motion vector may be called pair (Bi) prediction. Can be. Here, the L0 motion vector may indicate a motion vector associated with the reference picture list L0 (L0), and the L1 motion vector may indicate a motion vector associated with the reference picture list L1 (L1). The reference picture list L0 may include pictures that are earlier in the output order than the current picture as reference pictures, and the reference picture list L1 may include pictures that are later in the output order than the current picture. The previous pictures may be called forward (reference) pictures, and the subsequent pictures may be called reverse (reference) pictures. The reference picture list L0 may further include pictures that are later in the output order than the current picture as reference pictures. In this case, the previous pictures may be indexed first in the reference picture list L0 and the subsequent pictures may be indexed next. The reference picture list L1 may further include previous pictures as reference pictures in output order than the current picture. In this case, the subsequent pictures may be indexed first in the reference picture list 1 and the previous pictures may be indexed next. The output order may correspond to a picture order count (POC) order.

Inter prediction may be performed using motion information of the current block. The encoding apparatus may derive optimal motion information for the current block through a motion estimation procedure. For example, the encoding apparatus may search for a similar reference block having a high correlation using the original block in the original picture for the current block in fractional pixel units within a predetermined search range in the reference picture, thereby deriving motion information. Can be. Similarity of blocks can be derived based on the difference of phase based sample values. For example, the similarity of the blocks may be calculated based on the SAD between the current block (or template of the current block) and the reference block (or template of the reference block). In this case, motion information may be derived based on a reference block having the smallest SAD in the search area. The derived motion information may be signaled to the decoding apparatus according to various methods based on the inter prediction mode.

An embodiment of the present invention relates to inter prediction, and may propose a method for hardware-friendly improvement of a process of refining a motion vector. In other words, an embodiment of the present invention may propose various methods for adaptively determining a template region in order to remove a pipeline delay that may occur when using a template matching method. A method for grouping candidates may be proposed in consideration of memory bandwidth.

In other words, the process of predicting motion information in inter prediction may be essentially applied to reduce motion information and residual signals. A merge mode in which motion information is derived from neighboring blocks to save information on a motion vector and a reference block is an example of the process, and the accuracy of motion prediction can be improved by refining motion information derived from limited information. However, since the decoder-side motion derivation (DMVD) process has low affinity in hardware, one embodiment may propose a method that can utilize the DMVD process or method by improving it.

3 schematically illustrates an example of pipeline delay occurrence.

The template matching method, which is one of DMVD methods, may be applied based on a cost between a neighboring area of the current block and a neighboring block of the block indicated by the MVP candidate motion vector, by using this to update a candidate in the candidate list. Or reorder candidates in the candidate list. Here, the adjacent region may refer to a template or a template region, a candidate may refer to a motion information candidate, and the candidate list may refer to a motion information candidate list. Here, the adjacent region of the current block is used as the left peripheral region and the upper peripheral region of the current block, and the adjacent block of the block indicated by the MVP candidate motion vector is also used by the left peripheral region and the upper peripheral region of the block indicated by the MVP candidate motion vector. It became. However, when using such an area, a pipeline delay may occur.

For example, a general motion compensation (MC) process may include an MV request process and a process of reconstruction with the MC. Since the reference picture needs to be stored, the entire picture information can be stored in external memory or double date rate (DDR) due to the amount of data. If stored in external memory or DDR, 400 to 500 cycles are used to fetch data. Degree may be required. In order to reduce the latency, a request for fetching a reference block from DDR may be executed before motion compensation to be hidden during motion compensation of the previous block.

Referring to FIG. 3, a normal pipeline architecture may represent a general pipeline structure, and with TM (recon block) may represent a pipeline structure when using a template matching method. Here, the MV request may refer to a request for patching a reference block, and MC and Recon may refer to a process of restoring with the MC.

However, when refining or reordering the motion information using the template matching method, the reconstructed pixel value of the previous block may be required before the motion compensation of the current block, that is, before the MV request. Therefore, since the MV Request of the current block must be performed after the Recon of the previous block, pipeline delay may occur.

In one embodiment, a template region of a block may be adaptively determined to apply template matching without such a pipeline delay. That is, in an embodiment, in order to prevent pipeline delay, an area not included in a previous block (previous block) of the current block may be determined as a template area, and the block may be a quadtree (QT) or binary. A case in which a tree is divided into a binary tree (BT) and a ternary tree (TT) will be described below with reference to FIGS. 4 to 6.

4 illustrates an example in which a block is divided into quadtrees.

Referring to FIG. 4, the quadtree may use the upper region without delay and may use the left region without delay only when the index (pu index) in the partition is 2. That is, only when the index in the partition is 2, the upper region as well as the left region may be used as a template region without delay. Here, the index within the partition zone may be referred to as a partition index.

In other words, the block divided into quadtrees may be coded in the order of the upper left, upper right, lower left and lower right. Alternatively, the motion compensation and restoration process may be performed using the template region. Accordingly, the split index may be 0 in the upper left region, 1 in the upper right region, 2 in the lower left region, and 3 in the lower right region. Here, the block to be divided may be referred to as an upper block, and the divided upper left area, upper right area, lower left area and lower right area are referred to as the upper left block, upper right block, lower left block and lower right block, respectively. May be referred to.

For example, when the current block is an upper left region in a block having a partition index of 0, it may be as shown first in the top of FIG. 4. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is a right upper region in a block having a partition index of 1, the current block may be as shown second above from FIG. 4. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is a lower left region in a block having a partition index of 2, the current block may be the third as shown above in FIG. 4. That is, since neither the left peripheral region nor the upper peripheral region of the current block is included in the previous block (previous block), both the left peripheral region and the upper peripheral region may be used as the template region.

For example, when the current block is the lower right region in the block having the partition index of 3, the current block may be as shown fourth from the top of FIG. 4. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

Referring to FIG. 5, when the binary tree and the ternary tree are horizontally divided, the upper region may be available without delay when the partition index (pu index) is 0, and the left region may be available without delay when the binary index and the ternary tree are greater than zero. have. That is, when the partition index is 0, only the upper region may be used as the template region without delay, and when the partition index is 0, only the upper region is used.

In other words, a block divided into a binary tree may be coded in an upper and a lower order, and a block divided into a ternary tree may be coded in an upper, a middle and a lower order. Alternatively, the motion compensation and restoration process may be performed using the template region. Thus, when the block is divided into binary trees, the partition index may be 0 in the upper region of the block and 1 in the lower region. When the block is partitioned into the ternary tree, the partition index may be 0 in the block. The side region may be 1 and the lower region may be 2. Here, the block to be divided may be referred to as an upper block, and the divided upper and lower regions are the upper block and the lower block, respectively, and the upper region, the middle region, and the lower region are the upper block, the middle block, and the lower region, respectively. May be referred to as a block.

For example, when the current block is an upper region in a block having a partition index of 0 according to the binary tree, it may be as shown first in the upper left of FIG. 5. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is a lower region in a block having a partition index of 1 according to the binary tree, the second block may be the second from the upper left of FIG. 5. That is, since the delay may occur as the upper peripheral area of the current block is included in the previous block (the previous block), the left peripheral area of the current block may be used as the template area.

For example, when the current block is an upper region in a block having a partition index of 0 according to the ternary tree, it may be as shown first in the upper right of FIG. 5. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is a central region in a block having a partition index of 1 according to the ternary tree, the current block may be as shown second from the upper right of FIG. 5. That is, since the delay may occur as the upper peripheral area of the current block is included in the previous block (the previous block), the left peripheral area of the current block may be used as the template area.

For example, when the current block is a lower region in a block having a partition index of 2 according to the ternary tree, the current block may be the third as shown in the upper right of FIG. 5. That is, since the delay may occur as the upper peripheral area of the current block is included in the previous block (the previous block), the left peripheral area of the current block may be used as the template area.

Referring to FIG. 6, when the binary tree and the ternary tree are vertically partitioned, the upper region may be always available without delay regardless of the pu index. That is, only the upper region can be used as a template region without delay.

In other words, the blocks divided into binary trees may be coded in the left and right order, and the blocks divided into the ternary tree may be coded in the left, center and right order. Alternatively, the motion compensation and restoration process may be performed using the template region. Therefore, when the block is divided into binary trees, the partition index may be 0 in the left region and the right region in the block, and when the block is divided into the ternary tree, the partition index may be 0 in the block and the center of the left region in the block. The side region may be 1 and the right region may be 2. Here, the block to be divided may be referred to as an upper block, and the divided left and right regions are the left block and the right block, respectively, and the left region, the central region, and the right region are the left block, the center block, and the right region, respectively. May be referred to as a block.

For example, when the current block is a left region within a block having a partition index of 0 according to the binary tree, the current block may be the first shown in the upper left of FIG. 6. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is the right region in the block having the partition index of 1 according to the binary tree, the second block may be the second from the upper left of FIG. 6. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is a left region in a block having a partition index of 0 according to the ternary tree, the current block may be the first shown in the upper right of FIG. 6. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is a central region in a block having a partition index of 1 according to the ternary tree, the current block may be as shown second from the upper right of FIG. 6. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

For example, when the current block is a right region in a block having a partition index of 2 according to the ternary tree, the current block may be the third as shown in the upper right of FIG. 6. That is, since the delay may occur as the left peripheral area of the current block is included in the previous block (the previous block), the upper peripheral area of the current block may be used as the template area.

According to an embodiment, a usable template region may be determined according to each partitioning structure or information, and may be applied by checking availability on a block basis. In other words, one embodiment uses a partitioning structure (QT / BT / TT) of the current block, a split direction (horizontal / vertical) and a split index (pu index (0, 1, 2, 3) in the case of BT / TT). Availability can be checked and a template area can be determined or derived.

Referring to FIG. 7, an embodiment may obtain MERGE_INDEX and configure an MVP candidate list. Thereafter, the left template availability can be checked (bLeftAvail), and the above template availability can be checked (bAboveAvail). That is, it is possible to check whether the left peripheral area of the current block is included in the previous block (previous block) and check whether it is available as a template. You can check if it is possible.

Thereafter, an embodiment may determine whether at least one of the left template and the top template is available (bLeftAvail || bAboveAvail), and if not all, the related procedure or process may be terminated immediately. However, when at least one of the left template and the upper template is available, the candidate list may be rearranged based on the available template or template region, and the candidate may be derived from the candidate list to perform refinement. That is, rearrangement and refinement may be performed using a template matching method based on some regions of the left peripheral region and the upper peripheral region adjacent to the current block.

In addition, it is possible to determine whether to update based on the result of refinement. When updating, the refined candidate can be added to the MVP candidate list, and the duplicate check process, additional candidate addition process, and finally the MVP candidate list can be added. The update process can be performed. However, in the case of not updating based on the result of refinement, a duplicate check process, an additional candidate addition process, and a process of finally updating the MVP candidate list may be performed. Here, the additional candidate adding process may mean adding 0 vectors and / or various other candidates when the number of candidates in the candidate list is less than the maximum number, and finally updating the MVP candidate list. May refer to a process of finally updating the candidate list after adding additional candidates, but the process of adding additional candidates and finally updating the MVP candidate list may be omitted. Alternatively, the maximum number of candidates in the candidate list may be omitted.

Here, the availability check process of the left template and the availability check process of the upper template may be described in more detail as follows. One embodiment may first assume that the left template is not available (bLeftAvail = FALSE). Subsequently, it can be determined whether the partitioning structure is quadtree and the partition index is 2 (QT && pu idx == 2), the partitioning structure is a binary tree or ternary tree, the partition direction is horizontal, and the partition index is greater than 0 (BT / TT && Hor Split && idx> 0). If at least one of the two is satisfied or TRUE, it can be determined that the left template is available (bLeftAvail = TRUE). However, if both are not satisfied or both are FALSE, the assumption that the left template is not available may not be changed.

In addition, one embodiment may assume that the upper template is available (bAboveAvail = TRUE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the upper template is unavailable (bAboveAvail = FALSE). However, when not satisfied or FALSE, the assumption that the upper template is available may not be changed.

In the above-described embodiment, the availability of the template may be determined based on a partitioning structure and a partition index (pu index). That is, the availability of the templates on the left and top of the current block can be determined, and thus the left and / or top template region can be used.

However, an embodiment may minimize information and conditions that can be determined to reduce the complexity of the decoder. That is, an embodiment may use the partitioning structure (QT / BT / TT) of the current block, the split direction (horizontal / vertical) and the split index (pu index (0, 1, 2, 3)) in the case of BT / TT. However, if the partitioning structure is a quadtree, the condition for determining the partition index is 2 can be eliminated, and thus the information and conditions that can be determined can be minimized. The availability checking process can be described as follows.

Referring to FIG. 8, one embodiment may first assume that the left template is not available (bLeftAvail = FALSE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the template on the left is available (bLeftAvail = TRUE). However, in the case of not satisfied or FALSE, the assumption that the left template cannot be used may not be changed.

In other words, when divided into quadtrees, the partition index may not be considered and the upper template may be always used. In addition, when a partition is divided into a binary tree or a ternary tree and the split direction is vertical, the upper template may always be used without considering the split index. In addition, when the partition is divided into a binary tree or a ternary tree and the division direction is horizontal, an upper template may be used when the partition is 0, and a left template may be used when the partition is larger than 0.

As described above, the left peripheral region and the upper peripheral region of the current block may be used as the template region, and the left peripheral region or the upper peripheral region may be used as the template region.

According to an embodiment, when the left peripheral area or the upper peripheral area is used as the template area of the current block, each area may be extended. That is, when the left peripheral area of the current block is used as the template area, the left peripheral area may be extended. When the upper peripheral area of the current block is used as the template area, the upper peripheral area may be extended.

When the current block is a left region in which the partition index of the ternary tree in the vertical direction is 0, an upper peripheral region adjacent to the current block may be used as a template region. However, the width of the template region may be narrow due to the division according to the vertical ternary tree. That is, the accuracy may be reduced due to the narrow template area. Thus, an embodiment may extend the upper peripheral area used as the template area.

Referring to FIG. 9A, the template area of the current block may be an upper peripheral area adjacent to the current block, but may extend the height of the upper peripheral area. For example, the height of the upper peripheral area was 2 sample distances but could be extended to 4 sample distances.

Referring to FIG. 9B, the template area of the current block may be extended from an upper peripheral area adjacent to the current block to an upper peripheral area adjacent to the current block or a block before splitting. That is, the width of the upper peripheral area can be extended.

In this case, since the extended regions are not all included in the previous block (the previous block), the pipeline delay may not occur.

As described above, when the template region is extended, the availability check process of the left template and the availability check process of the upper template in the decoding process may be as follows.

Referring to FIG. 10, one embodiment may first assume that the left template is unavailable (bLeftAvail = FALSE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the template on the left is available (bLeftAvail = TRUE). However, in the case of not satisfied or FALSE, the assumption that the left template cannot be used may not be changed.

In addition, an embodiment may determine whether the left template is not available and the upper template is available (! BLeftAvail && bAboveAvail) based on the above-described determination. One embodiment may extend the upper template region as described above when it is satisfied or TRUE, and may not extend the upper template region when it is not satisfied or FALSE.

In an embodiment, the template area of the current block may be determined differently according to the split information of the previous block (the previous block). In the above-described bar, the case in which the previous block is vertically divided is described, but the previous block may be horizontally divided according to the binary tree or the ternary tree, or may be divided into quadtrees.

For example, referring to FIG. 11A, both the current block and the previous block may be divided into quadtrees. Here, when the current block is an upper left region in a block having a partition index of 0 according to the quadtree, since both the left peripheral region and the upper peripheral region of the current block are not included in the previous block (the previous block), the current block may be used as a template region. have.

For example, referring to FIG. 11B, the current block may be divided into a binary tree in the vertical direction, and the previous block may be divided into a quadtree. Here, when the current block is a left region in a block having a partition index of 0 according to the vertical binary tree, the upper peripheral region of the current block is not included in the previous block (previous block), and thus may be used as a template region. However, since only a part of the left peripheral area of the current block is included in the previous block, the left peripheral area may not be used as the template area. However, some regions not included in the previous block among the left peripheral regions may be used as template regions.

According to an embodiment, a usable template region may be determined according to partitioning information of a current block and a previous block, and the availability of a template area may be checked and applied in units of blocks. In other words, in one embodiment, the partitioning structure (QT / BT / TT) of the current block, the split direction (horizontal / vertical) in the case of BT / TT, the partition index (pu index (0, 1, 2, 3)), the current The availability of the block, the partitioning structure of the previous block (QT / BT / TT), and the size of the previous block may be used to check availability, and the template area may be determined or derived.

For example, one embodiment may check the availability of the left and upper blocks using the partitioning information, the partitioning direction, and the partition index of the current block, and for the case where the current block is divided into quadtrees and the partition index is 0. By comparing the height of the current block and the height of the left block, if the height of the left block is the same or less than the height of the current block, the left template area can be changed to be used.

For example, referring to FIG. 12, one embodiment may first assume that the left template is not available (bLeftAvail = FALSE). Then, it can be determined whether the partitioning structure of the current block is quadtree and the partition index is 2 (QT && pu idx == 2), and whether the partitioning structure is a binary tree or a ternary tree, the horizontal direction and the partition index is greater than zero ( BT / TT && Hor Split && idx> 0). One embodiment may determine that the left template is available if at least one of the two is satisfied or TRUE (bLeftAvail = TRUE). However, if both are not satisfied or FALSE, it is possible to determine whether the partition structure of the current block is quadtree and the partition index is 0 (QT && pu idx == 0), and the height of the current block (CurBlk_H) is It may be determined whether it is greater than or equal to the height LeftBlk_H of the block (or the previous block or the left block). One embodiment may determine that the left template is available if both are satisfied or TRUE (bLeftAvail = TRUE). However, if either of them is not satisfied or FALSE, the assumption that the left template is not available may not be changed.

In addition, one embodiment may assume that the upper template is available (bAboveAvail = TRUE). Then, it can be determined whether the partitioning structure of the current block is a binary tree or ternary tree, the split direction is horizontal, and the split index is greater than 0 (BT / TT && Hor Split && idx> 0), and if it is satisfied or TRUE, If so, it can be determined that the upper template is unavailable (bAboveAvail = FALSE). However, when not satisfied or FALSE, the assumption that the upper template is available may not be changed.

In addition, when only the upper peripheral area of the current block is available as a template area, the extension of the upper peripheral area may also be applied, and the availability of the left template area and the upper template area is checked, but the motion vector (MV) located on the upper side and the left side are checked. If the reliability is low by using only one side due to a large difference in MV located at, it may be checked whether the left template region is applied based on the condition in FIG. 12.

The template matching method according to an embodiment may be applied to the rearrangement process of the MVP candidate list. In this case, a motion compensation (MC) process of a template region is required for each candidate, and therefore, due to a patch from an external memory or a double data rate (DDR) within a limited memory bandwidth, Delays can occur. Accordingly, in order to solve the memory bandwidth problem, an embodiment may group the MVP candidate list and rearrange the candidates included in only a specific group.

For example, if there are six candidates in the MVP candidate list, they can be divided into two groups (Examples 1-[0, 1], [2, 3], [4, 5]) and divided into three groups. It may be divided (Example 2-[0, 1, 2], [3, 4, 5]). That is, the number of candidates for each group may vary according to the number of candidates. In addition, the number of candidates in each group may be different (Examples 3-[0, 1], [2, 3, 4, 5]), and only a specific group is targeted to reduce complexity (Examples 4-[0.1]. 2]) may be rearranged.

In one embodiment, when the prediction mode of the current block is the merge mode, the merge index (MERGE_INDEX) may be an index for indicating the MVP selected in the candidate list, and the decoding complexity may be improved by rearranging only the candidate group indicated by the index. have. In the above description, the MVP candidate or the MVP candidate list may be referred to as a merge candidate or a merge candidate list according to the merge mode.

Example 1 may be divided into three groups, so that the reordering range may be small. However, since template matching is performed on only two candidates in the group indicated by the index, efficiency in terms of complexity may be high. Also, Example 2 may be in a trade of relationship in reordering range and target candidates compared to Example 1. Example 3 can be applied to candidates with a high possibility of reordering, such as the [2, 3, 4, 5] group by including a different number of candidates for each group, and can take advantage in complexity and performance. Example 4 may reorder the specific group only, greatly reducing the complexity.

In one embodiment, candidates in the candidate list may be grouped, and since duplicate candidates may exist in each group, a new duplicate candidate may be added by performing a duplicate check. Here, the duplicate check may be referred to as a pruning process.

As described above, a method of determining a template area and a method of grouping candidates in a candidate list may be applied together as described above. That is, a template matching method may be used based on the determined template region, and thus the candidate list may be rearranged.

Referring to FIG. 13, an embodiment may obtain index information. Here, the index information may mean information indicating a specific candidate in the candidate list, and may also be referred to as a merge index or MERGE_INDEX. One embodiment may construct a candidate list of a group to which the index belongs. That is, the group including the candidate indicated by the index information in the candidate list and the candidates within the group can be derived. Then, one embodiment may check the availability of the template area of the current block. Here, the template region may include a left peripheral region and an upper peripheral region adjacent to the current block.

According to an embodiment, if there is a template region available, the candidate list may be rearranged based on the template region. That is, the candidate list may be rearranged based on the template area of the current block and the template area of the block indicated by the candidate. Here, the relative position between the current block and the template region may be the same as the relative position between the template region of the block indicated by the candidate and the block indicated by the candidate.

According to an embodiment, duplicate checks may be performed on candidates in a candidate list, and additional candidates may be added when the number of candidates in the candidate list is smaller than the maximum number because duplicate candidates are excluded due to the duplicate check. Based on this, the candidate list can be updated. However, when there is no duplicate candidate as a result of the duplicate check, the candidate list may be updated based on the rearranged candidate.

In addition, when an available template region does not exist, one embodiment may not perform a reordering process or the like and immediately terminate the related procedure or process.

According to an exemplary embodiment, a template matching method may be used based on the determined template region, and through this, not only the rearrangement of the candidate list but also refinement may be performed on the target candidate.

Referring to FIG. 14, an embodiment may obtain index information. Here, the index information may mean information indicating a specific candidate in the candidate list, and may also be referred to as a merge index or MERGE_INDEX. One embodiment may construct a candidate list of a group to which the index belongs. That is, the group including the candidate indicated by the index information in the candidate list and the candidates within the group can be derived. Then, one embodiment may check the availability of the template area of the current block. Here, the template region may include a left peripheral region and an upper peripheral region adjacent to the current block.

According to an embodiment, if there is a template region available, the candidate list may be rearranged based on the template region. That is, the candidate list may be rearranged based on the template area of the current block and the template area of the block indicated by the candidate. In addition, an embodiment may refine the target candidate in the candidate list based on the available template region. Here, the relative position between the current block and the template region may be the same as the relative position between the template region of the block indicated by the candidate and the block indicated by the candidate.

According to an embodiment, duplicate checks may be performed on candidates in a candidate list, and additional candidates may be added when the number of candidates in the candidate list is smaller than the maximum number because duplicate candidates are excluded due to the duplicate check. Based on this, the candidate list can be updated. However, if there are no candidates duplicated as a result of the duplicate check, the candidate list may be updated based on the candidate refined immediately.

The method disclosed in FIG. 15 may be performed by the encoding apparatus disclosed in FIG. 1. Specifically, for example, S1500 to S1540 of FIG. 15 may be performed by the prediction unit of the encoding apparatus, and S1550 may be performed by the entropy encoding unit of the encoding apparatus. In addition, although not shown, a process of deriving a residual sample for the current block based on the original sample and the prediction sample for the current block may be performed by a subtractor of the encoding apparatus, The generating of the information about the residual on the basis of the current block may be performed by a converter of the encoding apparatus. The encoding of the information on the residual and the prediction of the current block may be performed. It may be performed by the entropy encoding unit of the encoding device.

The encoding apparatus configures a merge candidate list of the current block (S1500). The encoding apparatus may derive neighboring blocks for the motion information candidate list of the current block among neighboring blocks of the current block. The encoding apparatus may select neighboring blocks for the motion information candidate list of the current block among the neighboring blocks of the current block. The encoding apparatus may construct the motion information candidate list based on the derived or selected neighboring blocks. The encoding apparatus may derive motion information of the selected neighboring blocks as motion information candidates of the current block, and construct the motion information candidate list including the motion information candidates. In addition, the encoding apparatus may derive the motion information derived by combining the motion information of the selected neighboring blocks as the motion information candidate of the current block, and configure the motion information candidate list including the motion information candidate. Meanwhile, the motion information candidate list may indicate a merge candidate list as the current block is a merge mode, but an MVP candidate list may be used when the current block is an AMVP mode.

The encoding apparatus derives a template region adjacent to the current block (S1510). The template region may include a region not included in a previous block restored immediately before the current block among a left peripheral region and an upper peripheral region adjacent to the current block. That is, the template region may be a left peripheral region adjacent to the current block, an upper peripheral region, and may be a left peripheral region and an upper peripheral region. However, the template area may be an area not included in the previous block (or the previous block) that is restored immediately before the pipeline delay does not occur. That is, the template region may be a region or a portion of the left peripheral region and the upper peripheral region not included in the previous block.

For example, the template region is partitioned when the partitioning structure information of the current block, the partitioning index information of the current block, and the partitioning structure of the current block are binary-tree or ternary-tree. It may be derived based on split direction information. Here, the split index information may be represented by pu index or pu idx and may have any one of 0, 1, 2, and 3.

For example, the template region may determine whether the left peripheral region is available (bLeftAvail), and then determine whether the upper peripheral region is available (bAboveAvail). Here, the left peripheral region may be referred to as a left template or left template region, and the upper peripheral region may be referred to as an upper template or an upper template region.

For example, first of all, it can be assumed that the left template is not available (bLeftAvail = FALSE). Thereafter, when the partitioning structure is a quadtree and the partition index information of the current block is 2, or the partitioning structure of the current block is a binary tree in a horizontal direction or a ternary tree in a horizontal direction, the partition index information of the current block. When is greater than 0, the template region may include the left peripheral region. That is, an embodiment may determine whether a partitioning structure is a quadtree and a partition index of 2 (QT && pu idx == 2) for the current block, the partitioning structure is a binary tree or a ternary tree, and the partitioning direction is horizontal. It may be determined whether the split index is greater than 0 (BT / TT & & Hor Split && idx> 0), and if at least one of the two is satisfied or TRUE, it may be determined that the left template is available. However, if both are not satisfied or both are FALSE, the assumption that the left template is not available may not be changed.

For example, when the partitioning structure of the current block is not a binary tree in the horizontal direction or a ternary tree in the horizontal direction, or when the partition index information of the current block is not greater than 0, the template area may include the upper peripheral area. It may include. That is, one embodiment may assume that the upper template is available (bAboveAvail = TRUE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the upper template is unavailable (bAboveAvail = FALSE). However, when not satisfied or FALSE, the assumption that the upper template is available may not be changed. A more detailed description has been given above with reference to FIG. 7.

For example, when the partitioning structure of the current block is not a horizontal binary-tree or a horizontal ternary-tree, or the partition index information of the current block is not greater than zero. The template region may not include the left peripheral region. That is, one embodiment may first assume that the left template is unavailable (bLeftAvail = FALSE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the template on the left is available (bLeftAvail = TRUE). However, in the case of not satisfied or FALSE, the assumption that the left template cannot be used may not be changed. In addition, one embodiment may assume that the upper template is available (bAboveAvail = TRUE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the upper template is unavailable (bAboveAvail = FALSE). However, when not satisfied or FALSE, the assumption that the upper template is available may not be changed. As described above, the complexity may be reduced by removing a condition for determining the case where the partition index is 2 when the partitioning structure is the quadtree. A more detailed description has been given above with reference to FIG. 8.

For example, when the template region includes the upper peripheral region, the width of the upper peripheral region may extend to the width of the upper block of the current block. In other words, the template area of the current block may be extended from an upper peripheral area adjacent to the current block to an upper peripheral area adjacent to the current block or a block before splitting. That is, when the upper peripheral area of the current block is used as the template area, the width of the upper peripheral area can be extended. In addition, one embodiment may extend the height of the upper peripheral area. A more detailed description has been given above with reference to FIGS. 9A and 9B.

For example, the template region may include partitioning structure information of the previous block, size information of the previous block, size information of the current block, partitioning structure information of the current block, partition index information of the current block, and the current block. If the partitioning structure is a binary-tree or ternary-tree, it may be derived based on split direction information. Here, the split index information may be represented by pu index or pu idx and may have any one of 0, 1, 2, and 3. In addition, the size information of the current block may include the height information of the current block, the height information of the current block may be represented by CurBlk_H. The size information of the previous block may include height information of the previous block, and the height information of the previous block may be represented as LeftBlk_H. Here, the previous block may be referred to as the left block because it may be located around the left side of the current block.

For example, when the partitioning structure of the current block is a quadtree, the partition index information of the current block is 0, and the height of the current block is greater than or equal to the height of the previous block, the template area is the left side. It may include a peripheral area. That is, one embodiment may first assume that the left template is unavailable (bLeftAvail = FALSE). Then, it can be determined whether the partitioning structure of the current block is quadtree and the partition index is 2 (QT && pu idx == 2), and whether the partitioning structure is a binary tree or a ternary tree, the horizontal direction and the partition index is greater than zero ( BT / TT && Hor Split && idx> 0). One embodiment may determine that the left template is available if at least one of the two is satisfied or TRUE (bLeftAvail = TRUE). However, if both are not satisfied or FALSE, it is possible to determine whether the partition structure of the current block is quadtree and the partition index is 0 (QT && pu idx == 0), and the height of the current block (CurBlk_H) is It may be determined whether it is greater than or equal to the height LeftBlk_H of the block (or the previous block or the left block). One embodiment may determine that the left template is available if both are satisfied or TRUE (bLeftAvail = TRUE). However, if either of them is not satisfied or FALSE, the assumption that the left template is not available may not be changed. In addition, one embodiment may assume that the upper template is available (bAboveAvail = TRUE). Then, it can be determined whether the partitioning structure of the current block is a binary tree or ternary tree, the split direction is horizontal, and the split index is greater than 0 (BT / TT && Hor Split && idx> 0), and if it is satisfied or TRUE, If so, it can be determined that the upper template is unavailable (bAboveAvail = FALSE). However, when not satisfied or FALSE, the assumption that the upper template is available may not be changed. A more detailed description has been given above with reference to FIG. 12.

The encoding apparatus rearranges the merge candidate list based on the template region (S1520). In other words, the candidate list may be rearranged based on the template area of the current block and the template area of the block indicated by the candidate. Here, the candidate may be a candidate included in the merge candidate list. Here, the relative position between the current block and the template region may be the same as the relative position between the template region of the block indicated by the candidate and the block indicated by the candidate.

For example, the encoding apparatus may group candidates in the merge candidate list and rearrange candidates in a group including candidates according to the merge index based on the template region. Here, grouping may be for solving the bandwidth problem. The encoding apparatus may group candidate lists to rearrange only candidates included in a specific group. In one embodiment, when the prediction mode of the current block is the merge mode, the merge index (MERGE_INDEX) may be an index for indicating the MVP selected in the candidate list, and complexity may be improved by rearranging only the candidate groups indicated by the index. .

Although not shown, the encoding apparatus may refine the target candidate in the candidate list based on the available template region. That is, the encoding apparatus may derive a specific candidate in the merge candidate list, refine the specific candidate based on the template region, and add the refined specific candidate to the merge candidate list. You can add That is, refinement may also be performed using the derived template region-based template matching method. Here, the relative position between the current block and the template region may be the same as the relative position between the template region of the block indicated by the candidate and the block indicated by the candidate.

The encoding apparatus derives the merge index of the current block (S1530). The merge index may indicate index information and may indicate MERGE_INDEX. The merge index may include information indicating a specific candidate to be used for prediction in the motion information candidate list. The encoding apparatus may select or derive a specific motion information candidate from among motion information candidates of the motion information candidate list based on a merge index, and may derive the selected motion information candidate as motion information for the current block. That is, the encoding apparatus may derive a merge index indicating a candidate to be derived to generate a predicted block of the current block in the merge candidate list.

The encoding apparatus generates a predicted block for the current block based on the merge index and the merge candidate list (S1540). That is, motion information may be derived based on the merge index and the merge candidate list. Alternatively, motion information may be derived based on a candidate indicated by the merge index in the merge candidate list. In addition, prediction of the current block may be performed based on the motion information. A prediction block of the current block may be derived based on the motion information, and a reconstruction block may be derived based on the prediction block. In detail, the encoding apparatus may derive a reference block within a reference picture based on the motion information. The motion information may include a motion vector and a reference picture index. The encoding apparatus may derive the reference picture indicated by the reference picture index among the reference pictures of the reference picture list as the reference picture of the current block, and convert the block indicated by the motion vector in the reference picture into the reference block of the current block. Can be derived. The encoding apparatus may generate a prediction sample based on the reference block.

In addition, the encoding apparatus may generate a residual sample based on the original sample and the generated prediction sample. The encoding apparatus may generate information about the residual based on the residual sample. The information about the residual may include transform coefficients related to the residual sample. The encoding apparatus may derive the reconstructed sample based on the prediction sample and the residual sample. That is, the encoding apparatus may derive the reconstructed sample by adding the prediction sample and the residual sample. Here, the encoding apparatus may generate a residual block based on the original block and the predicted block, and may generate information about the residual based on this. In addition, the encoding apparatus may encode the information about the residual and output the bitstream. The bitstream may be transmitted to a decoding apparatus via a network or a storage medium.

The encoding apparatus generates, encodes, and outputs prediction information about the current block (S1550). The encoding apparatus may encode and output the video information including the information on the prediction of the current block in the form of a bitstream. For example, the encoding apparatus may determine the prediction mode of the current block, and generate information indicating the prediction mode. In addition, information on the merge candidate list structure of the current block and information on the merge index may be generated. In addition, template related information, reordering related information, and / or refinement related information about the current block may be generated. In addition, information about the residual may be generated. The above-described information about prediction of the current block may include all of the above-described information or may include only a part of the information. The bitstream may be transmitted to a decoding apparatus via a network or a storage medium.

The method disclosed in FIG. 16 may be performed by the decoding apparatus disclosed in FIG. 2. Specifically, for example, S1600 to S1640 of FIG. 16 may be performed by the prediction unit of the decoding apparatus. In addition, although not shown, a process of acquiring image information including information on prediction of a current block and information on residual through a bitstream may be performed by an entropy decoding unit of the decoding apparatus. The process of deriving the residual sample for the current block based on the dual information may be performed by an inverse transform unit of the decoding apparatus, and the process of generating a reconstructed picture based on the prediction sample and the residual sample may be performed. It may be performed by an adder of the decoding apparatus.

The decoding apparatus derives the merge index of the current block (S1600). The merge index may indicate index information and may indicate MERGE_INDEX. The merge index may include information indicating a specific candidate to be used for prediction in the motion information candidate list. The decoding apparatus may select or derive a specific motion information candidate from the motion information candidates of the motion information candidate list to be described later based on the merge index, and may derive the selected motion information candidate as motion information for the current block.

The decoding apparatus configures a merge candidate list of the current block (S1610). The decoding apparatus may derive neighboring blocks for the motion information candidate list of the current block among neighboring blocks of the current block. The decoding apparatus may select neighboring blocks for the motion information candidate list of the current block among the neighboring blocks of the current block. The decoding apparatus may construct the motion information candidate list based on the derived or selected neighboring blocks. The decoding apparatus may derive the motion information of the selected neighboring blocks as motion information candidates of the current block, and construct the motion information candidate list including the motion information candidates. In addition, the decoding apparatus may derive the motion information derived by combining the motion information of the selected neighboring blocks as the motion information candidate of the current block, and configure the motion information candidate list including the motion information candidate. Meanwhile, the motion information candidate list may indicate a merge candidate list as the current block is a merge mode, but an MVP candidate list may be used when the current block is an AMVP mode.

The decoding apparatus derives a template region adjacent to the current block (S1620). The template region may include a region not included in a previous block restored immediately before the current block among a left peripheral region and an upper peripheral region adjacent to the current block. That is, the template region may be a left peripheral region adjacent to the current block, an upper peripheral region, and may be a left peripheral region and an upper peripheral region. However, the template area may be an area not included in the previous block (or the previous block) that is restored immediately before the pipeline delay does not occur. That is, the template region may be a region or a portion of the left peripheral region and the upper peripheral region not included in the previous block.

For example, when the partitioning structure of the current block is not a horizontal binary-tree or a horizontal ternary-tree, or the partition index information of the current block is not greater than zero. The template region may not include the left peripheral region. That is, one embodiment may first assume that the left template is unavailable (bLeftAvail = FALSE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the template on the left is available (bLeftAvail = TRUE). However, in the case of not satisfied or FALSE, the assumption that the left template cannot be used may not be changed. In addition, one embodiment may assume that the upper template is available (bAboveAvail = TRUE). Subsequently, it may be determined whether the partitioning structure is a binary tree or a ternary tree and the splitting direction is horizontal and the splitting index is greater than 0 (BT / TT && Hor Split && idx> 0). It can be determined that the upper template is unavailable (bAboveAvail = FALSE). However, when not satisfied or FALSE, the assumption that the upper template is available may not be changed. As described above, when the partitioning structure is a quadtree, the complexity of the decoder may be reduced by removing a condition for determining the case where the partition index is 2. A more detailed description has been given above with reference to FIG. 8.

The decoding apparatus rearranges the merge candidate list based on the template region in operation S1630. In other words, the candidate list may be rearranged based on the template area of the current block and the template area of the block indicated by the candidate. Here, the candidate may be a candidate included in the merge candidate list. Here, the relative position between the current block and the template region may be the same as the relative position between the template region of the block indicated by the candidate and the block indicated by the candidate.

For example, the decoding apparatus may group candidates in the merge candidate list and rearrange candidates in a group including candidates according to the merge index based on the template region. Here, grouping may be for solving the bandwidth problem. The decoding apparatus may group the candidate list and rearrange only the candidates included in the specific group. In one embodiment, when the prediction mode of the current block is the merge mode, the merge index (MERGE_INDEX) may be an index for indicating the MVP selected in the candidate list, and the decoding complexity may be improved by rearranging only the candidate group indicated by the index. have.

Although not shown, the decoding apparatus may perform refinement on the target candidate in the candidate list based on the available template region. That is, the decoding apparatus may derive a specific candidate in the merge candidate list, refine the specific candidate based on the template region, and add the refined specific candidate to the merge candidate list. You can add That is, refinement may also be performed using the derived template region-based template matching method. Here, the relative position between the current block and the template region may be the same as the relative position between the template region of the block indicated by the candidate and the block indicated by the candidate.

The decoding apparatus generates a predicted block for the current block based on the merge index and the merge candidate list (S1640). That is, motion information may be derived based on the merge index and the merge candidate list. Alternatively, motion information may be derived based on a candidate indicated by the merge index in the merge candidate list. In addition, prediction of the current block may be performed based on the motion information. A prediction block of the current block may be derived based on the motion information, and a reconstruction block may be derived based on the prediction block. In detail, the decoding apparatus may derive a reference block within a reference picture based on the motion information. The motion information may include a motion vector and a reference picture index. The decoding apparatus may derive the reference picture indicated by the reference picture index among the reference pictures of the reference picture list as the reference picture of the current block, and convert the block indicated by the motion vector in the reference picture as the reference block of the current block. Can be derived. The decoding apparatus may generate a prediction sample based on the reference block, and may directly use the prediction sample as a reconstruction sample according to a prediction mode, or generate a reconstruction sample by adding a residual sample to the prediction sample. . If there is a residual sample for the current block, the decoding apparatus may obtain information about the residual for the current block from the bitstream. The information about the residual may include transform coefficients regarding the residual sample. The decoding apparatus may derive the residual sample (or residual sample array) for the current block based on the residual information. The decoding apparatus may generate a reconstructed sample based on the prediction sample and the residual sample, and may derive a reconstructed block or a reconstructed picture based on the reconstructed sample. Thereafter, as described above, the decoding apparatus may apply an in-loop filtering procedure, such as a deblocking filtering and / or SAO procedure, to the reconstructed picture in order to improve subjective / objective picture quality as necessary.

In the above-described embodiment, the methods are described based on a flowchart as a series of steps or blocks, but the present invention is not limited to the order of steps, and any steps may occur in a different order or simultaneously from other steps as described above. have. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

The above-described method according to the present invention may be implemented in software, and the encoding device and / or the decoding device according to the present invention may perform image processing of, for example, a TV, a computer, a smartphone, a set-top box, a display device, and the like. It can be included in the device.

When embodiments of the present invention are implemented in software, the above-described method may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in memory and executed by a processor. The memory may be internal or external to the processor and may be coupled to the processor by various well known means. The processor may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage device.

17 schematically illustrates a content streaming system structure.

That is, the embodiments described in the present invention may be implemented and performed on a processor, a microprocessor, a controller or a chip. For example, the functional units shown in each drawing may be implemented and performed on a computer, processor, microprocessor, controller, or chip.

In addition, the decoding apparatus and encoding apparatus to which the present invention is applied include a multimedia broadcasting transmitting and receiving device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video chat device, a real time communication device such as video communication, and mobile streaming. Devices, storage media, camcorders, video on demand (VoD) service providers, over the top video (OTT) devices, internet streaming service providers, 3D (3D) video devices, video telephony video devices, and medical video devices It may be included and used to process a video signal or a data signal. For example, the OTT video device may include a game console, a Blu-ray player, an internet access TV, a home theater system, a smartphone, a tablet PC, a digital video recorder (DVR), and the like.

In addition, the processing method to which the present invention is applied can be produced in the form of a program executed by a computer, and can be stored in a computer-readable recording medium. Multimedia data having a data structure according to the present invention can also be stored in a computer-readable recording medium. The computer readable recording medium includes all kinds of storage devices and distributed storage devices in which computer readable data is stored. The computer-readable recording medium may be, for example, a Blu-ray disc (BD), a universal serial bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical disc. It may include a data storage device. The computer-readable recording medium also includes media embodied in the form of a carrier wave (for example, transmission over the Internet). In addition, the bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted through a wired or wireless communication network. In addition, an embodiment of the present invention may be implemented as a computer program product by program code, which may be performed on a computer by an embodiment of the present invention. The program code may be stored on a carrier readable by a computer.

In addition, the content streaming system to which the present invention is applied may largely include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.

The encoding server compresses content input from multimedia input devices such as a smart phone, a camera, a camcorder, etc. into digital data to generate a bitstream and transmit the bitstream to the streaming server. As another example, when multimedia input devices such as smart phones, cameras, camcorders, etc. directly generate a bitstream, the encoding server may be omitted. The bitstream may be generated by an encoding method or a bitstream generation method to which the present invention is applied, and the streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.

The streaming server transmits the multimedia data to the user device based on the user's request through the web server, and the web server serves as a medium for informing the user of what service. When a user requests a desired service from the web server, the web server delivers it to a streaming server, and the streaming server transmits multimedia data to the user. In this case, the content streaming system may include a separate control server. In this case, the control server plays a role of controlling a command / response between devices in the content streaming system.

The streaming server may receive content from a media store and / or an encoding server. For example, when the content is received from the encoding server, the content may be received in real time. In this case, in order to provide a smooth streaming service, the streaming server may store the bitstream for a predetermined time.

Examples of the user device include a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), navigation, a slate PC, Tablet PCs, ultrabooks, wearable devices, such as smartwatches, glass glasses, head mounted displays, digital TVs, desktops Computer, digital signage, and the like. Each server in the content streaming system may be operated as a distributed server, in which case data received from each server may be distributed.

Claims

In the image decoding method performed by the decoding apparatus,

Deriving a merge index of the current block;

Constructing a merge candidate list of the current block;

Deriving a template region adjacent to the current block;

Reordering the merge candidate list based on the template region; And

Generating a predicted block for the current block based on the merge index and the merge candidate list,

And the template region includes a region not included in a previous block to be restored immediately before the current block among a left peripheral region and an upper peripheral region adjacent to the current block.
The method of claim 1,

The template region may have a partitioning direction when partitioning structure information of the current block, partition index information of the current block, and a partitioning structure of the current block are binary-tree or ternary-tree. The image decoding method, characterized in that derived based on the information.
The method of claim 1,

If the partitioning structure of the current block is a quadtree and the partition index information of the current block is 2, or the partitioning structure of the current block is a horizontal binary tree or a horizontal ternary tree ( ternary-tree), when the partition index information of the current block is greater than 0, the template region includes the left peripheral region.
The method of claim 1,

The template region when the partitioning structure of the current block is not a horizontal binary-tree or a horizontal ternary-tree or when the partition index information of the current block is not greater than zero. Is characterized by including the upper peripheral region.
The method of claim 1,

The template region when the partitioning structure of the current block is not a horizontal binary-tree or a horizontal ternary-tree or when the partition index information of the current block is not greater than zero. Does not include the left peripheral region.
The method of claim 1,

And when the template region includes the upper peripheral region, the width of the upper peripheral region extends to the width of an upper block of the current block.
The method of claim 1,

The template region may include binary partitioning structure information of the previous block, size information of the previous block, size information of the current block, partitioning structure information of the current block, partition index information of the current block, and partitioning structure of the current block. In the case of a binary tree or a ternary tree, the image decoding method is derived based on split direction information.
The method of claim 1,

If the partitioning structure of the current block is a quadtree, the partition index information of the current block is 0, and the height of the current block is greater than or equal to the height of the previous block, the template region includes the left peripheral region. The video decoding method, characterized in that.
The method of claim 1,

Reordering the merge candidate list based on the template region,

Grouping candidates in the merge candidate list; And

And rearranging the candidates in the group including the candidates according to the merge index based on the template region.
The method of claim 1,

Deriving a specific candidate in the merge candidate list;

Refining the specific candidate based on the template region; And

And adding the refined specific candidate to the merge candidate list.
In the video encoding method performed by the encoding device,

Constructing a merge candidate list of the current block;

Deriving a template region adjacent to the current block;

Reordering the merge candidate list based on the template region;

Deriving a merge index of the current block;

Generating a predicted block for the current block based on the merge index and the merge candidate list; And

Generating, encoding, and outputting prediction information about the current block;

And the template region includes a region of a left peripheral region and an upper peripheral region adjacent to the current block not included in a previous block to be restored immediately before the current block.
The method of claim 11,

The template region may have a partitioning direction when partitioning structure information of the current block, partition index information of the current block, and a partitioning structure of the current block are binary-tree or ternary-tree. The image encoding method, characterized in that derived based on the information.
The method of claim 11,

If the partitioning structure of the current block is a quadtree and the partition index information of the current block is 2, or the partitioning structure of the current block is a horizontal binary tree or a horizontal ternary tree ( ternary-tree), when the partition index information of the current block is greater than 0, the template region includes the left peripheral region.
The method of claim 11,

The template region when the partitioning structure of the current block is not a horizontal binary-tree or a horizontal ternary-tree or when the partition index information of the current block is not greater than zero. Is characterized by including the upper peripheral region.
A decoding apparatus for performing an image decoding method,

An entropy decoding unit for obtaining prediction information on the current block; And

Derive a merge index of a current block, construct a merge candidate list of the current block, derive a template region adjacent to the current block, rearrange the merge candidate list based on the template region, and merge the merge index and the A prediction unit generating a predicted block for the current block based on a merge candidate list,

And the template region includes a region not included in a previous block to be restored immediately before the current block among a left peripheral region and an upper peripheral region adjacent to the current block.