1. A method for decoding a video, the method comprising: determining whether to split a parent node coding block based on quad-tree partitioning; determining whether to split the parent node coding block based on binarytree partitioning when it is determined that the parent node coding block is not split based on the quad-tree partitioning; splitting the parent node coding block into two non-square coding blocks of the same size by applying horizontal binary-tree partitioning or vertical binary-tree 10 partitioning when it is determined to split the parent node coding block based on the binary-tree partitioning; determining whether to split one of the non-square coding blocks into two partitions or not; and splitting the non-square coding block into two partitions by applying either the horizontal binary-tree partitioning or the vertical binary-tree partitioning when it is determined to split the non-square coding block, wherein when the parent node coding block is split based on the horizontal binary-tree partitioning, the horizontal binary-tree partitioning is determined not to be allowed to the non-square coding block, wherein when the parent node coding block is split based on the vertical binary-tree partitioning, the vertical binary-tree partitioning is determined not to be allowed to the non-square coding block, and wherein the parent node coding block has a size of 128x128.

2. The method of claim 1, wherein the method further comprises decoding size information specifying a size of a merge process region, and wherein if both the non-square coding blocks are included in the same merge processing region, one of the non-square coding blocks is not available as a merge candidate for the other of the non-square coding blocks.

3. A method for encoding a video, the method comprising: determining whether to split a parent node coding block based on quad-tree partitioning; determining whether to split the parent node coding block based on binary tree partitioning when it is determined that the parent node coding block is not split based on the quad-tree partitioning; splitting the parent node coding block into two non-square coding blocks of the same size by applying horizontal line binary-tree partitioning or vertical binarytree partitioning when it is determined to split the parent node coding block based on the binary-tree partitioning; and determining whether to split one of the non-square coding blocks into two partitions or not; and splitting the non-square coding block into two partitions by applying either the horizontal binary-tree partitioning or the vertical binary-tree partitioning when it is determined to split the non-square coding block, wherein when the parent node coding block is split based on the horizontal binary-tree partitioning, the horizontal binary-tree partitioning is determined not to be allowed to the non-square coding block, wherein when the parent node coding block is split based on the vertical binary-tree partitioning, the vertical binary-tree partitioning is determined not to be allowed to the non-square coding block, and wherein the parent node coding block has a size of 128x128.

4. The method of claim 3, wherein the method further comprises determining a size of a merge processing region, and wherein if both the non-square coding blocks are included in the same merge processing region, one of the non-square coding blocks is not available as a merge candidate for the other of the non-square coding blocks.

5. An apparatus (100) for encoding a video, the apparatus comprising: a picture partitioning unit (110) to: determine whether to split a parent node coding block based on quad-tree partitioning, determine whether to split the parent node coding block based on binarytree partitioning when it is determined that the parent node coding block is not split based on the quad-tree partitioning, split the parent node coding block into two non-square coding blocks of the same size by applying horizontal binary-tree partitioning or vertical binary-tree partitioning when it is determined to split the parent node coding block based on the binary-tree partitioning, determine whether to split one of the non-square coding blocks into two partitions or not, and split the non-square coding block into two partitions by applying either the horizontal binary-tree partitioning or the vertical binary-tree partitioning when it is determined to split the non-square coding block, wherein when the parent node coding block is split based on the horizontal binary-tree partitioning, the horizontal binary-tree partitioning is determined not to be allowed to the non-square coding block, wherein when the parent node coding block is split based on the vertical binary-tree partitioning, the vertical binary-tree partitioning is determined not to be allowed to the non-square coding block, and wherein the parent node coding block has a size of 128x128. This is a Divisional Application of Parent/Original Application 201917002143 Dated 17 January 2019 DESCRIPTION Technical Field [0001] The present invention relates to a method and an apparatus for processing video signal. Background Art [0002] Recently, demands for high-resolution and high-quality images such as high definition (HD) images and ultra-high definition (UHD) images have increased in various application fields. However, higher resolution and quality image data has increasing amounts of data in comparison with conventional image data. Therefore, when transmitting image data by using a medium such as conventional wired and wireless broadband networks, or when storing image data by using a conventional storage medium, costs of transmitting and storing increase. In order to solve these problems occurring with an increase in resolution and quality of image data, high-efficiency image encoding/decoding techniques may be utilized. [0003] Image compression technology includes various techniques, including: an inter-prediction technique of predicting a pixel value included in a current picture from a previous or subsequent picture of the current picture; an intra-prediction technique of predicting a pixel value included in a current picture by using pixel information in the current picture; an entropy encoding technique of assigning a short code to a value with a high appearance frequency and assigning a long code to a value with a low appearance frequency; etc. Image data may be effectively compressed by using such image compression technology, and may be transmitted or stored. [0004] In the meantime, with demands for high-resolution images, demands for stereographic image content, which is a new image service, have also increased. A video compression technique for effectively providing stereographic image content with high resolution and ultra-high resolution is being discussed. Disclosure Technical Problem [0005] An object of the present invention is to provide a method and an apparatus for efficiently performing inter prediction for an encoding/decoding target block in encoding/decoding a video signal. [0006] An object of the present invention is to provide a method and an apparatus for deriving a merge candidate based on a block having a pre-determined shape or a pre-determined size in encoding/decoding a video signal. [0007] An object of the present invention is to provide a method and an apparatus for performing a merge in parallel in a unit of a pre-determined shape or a pre-determined size in encoding/decoding a video signal. [0008] The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems. And, other technical problems that are not mentioned will be apparently understood to those skilled in the art from the following description. Technical Solution [0009] A method and an apparatus for decoding a video signal according to the present invention may derive a spatial merge candidate for a current block, generate a merge candidate list for the current block based on the spatial merge candidate, obtain motion information for the current block based on the merge candidate list, and perform motion compensation for the current block using the motion information. [0010] A method and an apparatus for encoding a video signal according to the present invention may derive a spatial merge candidate for a current block, generate a merge candidate list for the current block based on the spatial merge candidate, obtain motion information for the current block based on the merge candidate list, and perform motion compensation for the current block using the motion information. [0011] In the method and the apparatus for encoding/decoding a video signal according to the present invention, if the current block does not have a pre-defined shape or does not have a size equal to or greater than a pre-defined size, the spatial merge candidate of the current block may be derived based on a block having the pre-defined shape or having a size equal to or greater than the pre-defined size, the block comprising the current block. [0012] In the method and the apparatus for encoding/decoding a video signal according to the present invention, the pre-defined shape may be a square shape. [0013] In the method and the apparatus for encoding/decoding a video signal according to the present invention, the current block may have a same spatial merge candidate as a neighboring block included in the block of the square shape with the current block. [0014] In the method and the apparatus for encoding/decoding a video signal according to the present invention, if the current block and the spatial merge candidate are included in a same merge estimation region, the spatial merge candidate may be determined to be unavailable. [0015] In the method and the apparatus for encoding/decoding a video signal according to the present invention, the merge estimation region may have a square shape or a non-square shape. [0016] In the method and the apparatus for encoding/decoding a video signal according to the present invention, if the merge estimation region has the non-square shape, a number of candidate shapes of merge candidates that the merge estimation region is able to have may be restricted by a pre-defined number. [0017] The features briefly summarized above for the present invention are only illustrative aspects of the detailed description of the invention that follows, but do not limit the scope of the invention. Advantageous Effects [0018] According to the present invention, an efficient inter prediction may be performed for an encoding/decoding target block. [0019] According to the present invention, a merge candidate may be derived based on a block having a pre¬determined shape or a pre-determined size. [0020] According to the present invention, a merge can be performed in parallel in a unit of a pre¬determined shape or a pre-determined size. [0021] According to the present invention, intra prediction for an encoding/decoding target block may be performed by selecting at least one of a plurality of reference lines. [0022] According to the present invention, a reference line may be derived based on a block having a pre-determined shape or having a size equal to or greater than a pre-determined size. [0023] According to the present invention, an intra filter may be applied to at least one of a plurality of reference lines. [0024] According to the present invention, an intra prediction mode or a number of the intra prediction mode may be adaptively determined according to a reference line used for intra prediction of a current block. [0025] The effects obtainable by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. Description of Drawings [0026] FIG. 1 is a block diagram illustrating a device for encoding a video according to an embodiment of the present invention. [0027] FIG. 2 is a block diagram illustrating a device for decoding a video according to an embodiment of the present invention. [0028] FIG. 3 is a diagram illustrating an example of hierarchically partitioning a coding block based on a tree structure according to an embodiment of the present invention. [0029] FIG. 4 is a diagram illustrating a partition type in which binary tree-based partitioning is allowed according to an embodiment of the present invention. [0030] FIG. 5 is a diagram illustrating an example in which only a binary tree-based partition of a pre¬determined type is allowed according to an embodiment of the present invention. [0031] FIG. 6 is a diagram for explaining an example in which information related to the allowable number of binary tree partitioning is encoded/decoded, according to an embodiment to which the present invention is applied. [0032] FIG. 7 is a diagram illustrating a partition mode applicable to a coding block according to an embodiment of the present invention. [0033] FIG. 8 is a flowchart illustrating an inter prediction method according to an embodiment of the present invention. [0034] FIG. 9 is a diagram illustrating a process of deriving motion information of a current block when a merge mode is applied to a current block. [0035] FIG. 10 illustrates a process of deriving motion information of a current block when an AMVP mode is applied to the current block. [0036] FIG. 11 is a diagram showing a spatial merge candidate of a current block. [0037] FIG. 12 is a diagram showing a co-located block of a current block. [0038] FIG. 13 is a diagram for explaining an example of obtaining a motion vector of a temporal merge candidate by scaling a motion vector of a co-located block. [0039] FIG. 14 is a diagram showing an example of deriving a merge candidate of a non-square block on the basis of a square block. [0040] FIG. 15 is a diagram for explaining an example in which a merge candidate of a binary-tree partitioned block is derived based on an upper node block. [0041] FIG. 16 is a diagram illustrating an example of determining availability of a spatial merge candidate according to a merge estimation region. [0042] FIG. 17 is a flowchart illustrating processes of obtaining a residual sample according to an embodiment to which the present invention is applied. Mode for Invention [0043] A variety of modifications may be made to the present invention and there are various embodiments of the present invention, examples of which will now be provided with reference to drawings and described in detail. However, the present invention is not limited thereto, and the exemplary embodiments can be construed as including all modifications, equivalents, or substitutes in a technical concept and a technical scope of the present invention. The similar reference numerals refer to the similar element in described the drawings. [0044] Terms used in the specification, 'first', 'second' , etc. can be used to describe various components, but the components are not to be construed as being limited to the terms. The terms are only used to differentiate one component from other components. For example, the 'first' component may be named the 'second' component without departing from the scope of the present invention, and the 'second' component may also be similarly named the 'first' component. The term 'and/or' includes a combination of a plurality of items or any one of a plurality of terms. [0045] It will be understood that when an element is simply referred to as being 'connected to' or 'coupled to' another element without being 'directly connected to' or 'directly coupled to' another element in the present description, it may be 'directly connected to' or 'directly coupled to' another element or be connected to or coupled to another element, having the other element intervening therebetween. In contrast, it should be understood that when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements present. [0046] The terms used in the present specification are merely used to describe particular embodiments, and are not intended to limit the present invention. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. In the present specification, it is to be understood that terms such as "including", "having", etc. are intended to indicate the existence of the features, numbers, steps, actions, elements, parts, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, numbers, steps, actions, elements, parts, or combinations thereof may exist or may be added. [0047] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same constituent elements in the drawings are denoted by the same reference numerals, and a repeated description of the same elements will be omitted. [0048] FIG. 1 is a block diagram illustrating a device for encoding a video according to an embodiment of the present invention. [0049] Referring to FIG. 1, the device 100 for encoding a video may include: a picture partitioning module 110, prediction modules 120 and 125, a transform module 130, a quantization module 135, a rearrangement module 160, an entropy encoding module 165, an inverse quantization module 140, an inverse transform module 145, a filter module 150, and a memory 155. [0050] The constitutional parts shown in FIG. 1 are independently shown so as to represent characteristic functions different from each other in the device for encoding a video. Thus, it does not mean that each constitutional part is constituted in a constitutional unit of separated hardware or software. In other words, each constitutional part includes each of enumerated constitutional parts for convenience. Thus, at least two constitutional parts of each constitutional part may be combined to form one constitutional part or one constitutional part may be divided into a plurality of constitutional parts to perform each function. The embodiment where each constitutional part is combined and the embodiment where one constitutional part is divided are also included in the scope of the present invention, if not departing from the essence of the present invention. [0051] Also, some of constituents may not be indispensable constituents performing essential functions of the present invention but be selective constituents improving only performance thereof. The present invention may be implemented by including only the indispensable constitutional parts for implementing the essence of the present invention except the constituents used in improving performance. The structure including only the indispensable constituents except the selective constituents used in improving only performance is also included in the scope of the present invention. [0052] The picture partitioning module 110 may partition an input picture into one or more processing units. Here, the processing unit may be a prediction unit (PU) , a transform unit (TU) , or a coding unit (CU). The picture partitioning module 110 may partition one picture into combinations of multiple coding units, prediction units, and transform units, and may encode a picture by selecting one combination of coding units, prediction units, and transform units with a predetermined criterion (e.g., cost function). [0053] For example, one picture may be partitioned into multiple coding units. A recursive tree structure, such as a quad tree structure, may be used to partition a picture into coding units. A coding unit which is partitioned into other coding units with one picture or a largest coding unit as a root may be partitioned with child nodes corresponding to the number of partitioned coding units. A coding unit which is no longer partitioned by a predetermined limitation serves as a leaf node. That is, when it is assumed that only square partitioning is possible for one coding unit, one coding unit may be partitioned into four other coding units at most. [0054] Hereinafter, in the embodiment of the present invention, the coding unit may mean a unit performing encoding, or a unit performing decoding. [0055] A prediction unit may be one of partitions partitioned into a square or a rectangular shape having the same size in a single coding unit, or a prediction unit may be one of partitions partitioned so as to have a different shape / size in a single coding unit. [0056] When a prediction unit subjected to intra prediction is generated based on a coding unit and the coding unit is not the smallest coding unit, intra prediction may be performed without partitioning the coding unit into multiple prediction units NxN. [0057] The prediction modules 120 and 125 may include an inter prediction module 120 performing inter prediction and an intra prediction module 125 performing intra prediction. Whether to perform inter prediction or intra prediction for the prediction unit may be determined, and detailed information (e.g., an intra prediction mode, a motion vector, a reference picture, etc.) according to each prediction method may be determined. Here, the processing unit subjected to prediction may be different from the processing unit for which the prediction method and detailed content is determined. For example, the prediction method, the prediction mode, etc. may be determined by the prediction unit, and prediction may be performed by the transform unit. A residual value (residual block) between the generated prediction block and an original block may be input to the transform module 130. Also, prediction mode information, motion vector information, etc. used for prediction may be encoded with the residual value by the entropy encoding module 165 and may be transmitted to a device for decoding a video. When a particular encoding mode is used, it is possible to transmit to a device for decoding video by encoding the original block as it is without generating the prediction block through the prediction modules 120 and 125. [0058] The inter prediction module 120 may predict the prediction unit based on information of at least one of a previous picture or a subsequent picture of the current picture, or may predict the prediction unit based on information of some encoded regions in the current picture, in some cases. The inter prediction module 120 may include a reference picture interpolation module, a motion prediction module, and a motion compensation module. [0059] The reference picture interpolation module may receive reference picture information from the memory 155 and may generate pixel information of an integer pixel or less then the integer pixel from the reference picture. In the case of luma pixels, an 8-tap DCT-based interpolation filter having different filter coefficients may be used to generate pixel information of an integer pixel or less than an integer pixel in a unit of a 1/4 pixel. In the case of chroma signals, a 4-tap DCT-based interpolation filter having different filter coefficient may be used to generate pixel information of an integer pixel or less than an integer pixel in a unit of a 1/8 pixel. [0060] The motion prediction module may perform motion prediction based on the reference picture interpolated by the reference picture interpolation module. As methods for calculating a motion vector, various methods, such as a full search-based block matching algorithm (FBMA), a three step search (TSS), a new three-step search algorithm (NTS), etc., may be used. The motion vector may have a motion vector value in a unit of a 1/2 pixel or a 1/4 pixel based on an interpolated pixel. The motion prediction module may predict a current prediction unit by changing the motion prediction method. As motion prediction methods, various methods, such as a skip method, a merge method, an AMVP (Advanced Motion Vector Prediction) method, an intra block copy method, etc., may be used. [0061] The intra prediction module 125 may generate a prediction unit based on reference pixel information neighboring to a current block which is pixel information in the current picture. When the neighboring block of the current prediction unit is a block subjected to inter prediction and thus a reference pixel is a pixel subjected to inter prediction, the reference pixel included in the block subjected to inter prediction may be replaced with reference pixel information of a neighboring block subjected to intra prediction. That is, when a reference pixel is not available, at least one reference pixel of available reference pixels may be used instead of unavailable reference pixel information. [0062] Prediction modes in intra prediction may include a directional prediction mode using reference pixel information depending on a prediction direction and a non-directional prediction mode not using directional information in performing prediction. A mode for predicting luma information may be different from a mode for predicting chroma information, and in order to predict the chroma information, intra prediction mode information used to predict luma information or predicted luma signal information may be utilized. [0063] In performing intra prediction, when the size of the prediction unit is the same as the size of the transform unit, intra prediction may be performed on the prediction unit based on pixels positioned at the left, the top left, and the top of the prediction unit. However, in performing intra prediction, when the size of the prediction unit is different from the size of the transform unit, intra prediction may be performed using a reference pixel based on the transform unit. Also, intra prediction using NxN partitioning may be used for only the smallest coding unit. [0064] In the intra prediction method, a prediction block may be generated after applying an AIS (Adaptive Intra Smoothing) filter to a reference pixel depending on the prediction modes. The type of the AIS filter applied to the reference pixel may vary. In order to perform the intra prediction method, an intra prediction mode of the current prediction unit may be predicted from the intra prediction mode of the prediction unit neighboring to the current prediction unit. In prediction of the prediction mode of the current prediction unit by using mode information predicted from the neighboring prediction unit, when the intra prediction mode of the current prediction unit is the same as the intra prediction mode of the neighboring prediction unit, information indicating that the prediction modes of the current prediction unit and the neighboring prediction unit are equal to each other may be transmitted using predetermined flag information. When the prediction mode of the current prediction unit is different from the prediction mode of the neighboring prediction unit, entropy encoding may be performed to encode prediction mode information of the current block. [0065] Also, a residual block including information on a residual value which is a different between the prediction unit subjected to prediction and the original block of the prediction unit may be generated based on prediction units generated by the prediction modules 120 and 125. The generated residual block may be input to the transform module 130. [0066] The transform module 130 may transform the residual block including the information on the residual value between the original block and the prediction unit generated by the prediction modules 120 and 125 by using a transform method, such as discrete cosine transform (DCT), discrete sine transform (DST) , and KLT. Whether to apply DCT, DST, or KLT in order to transform the residual block may be determined based on intra prediction mode information of the prediction unit used to generate the residual block. [0067] The quantization module 135 may quantize values transformed to a frequency domain by the transform module 130. Quantization coefficients may vary depending on the block or importance of a picture. The values calculated by the quantization module 135 may be provided to the inverse quantization module 14 0 and the rearrangement module 160. [0068] The rearrangement module 160 may rearrange coefficients of quantized residual values. [0069] The rearrangement module 160 may change a coefficient in the form of a two-dimensional block into a coefficient in the form of a one-dimensional vector through a coefficient scanning method. For example, the rearrangement module 160 may scan from a DC coefficient to a coefficient in a high frequency domain using a zigzag scanning method so as to change the coefficients to be in the form of one-dimensional vectors. Depending on the size of the transform unit and the intra prediction mode, vertical direction scanning where coefficients in the form of two-dimensional blocks are scanned in the column direction or horizontal direction scanning where coefficients in the form of two-dimensional blocks are scanned in the row direction may be used instead of zigzag scanning. That is, which scanning method among zigzag scanning, vertical direction scanning, and horizontal direction scanning is used may be determined depending on the size of the transform unit and the intra prediction mode. [0070] The entropy encoding module 165 may perform entropy encoding based on the values calculated by the rearrangement module 160. Entropy encoding may use various encoding methods, for example, exponential Golomb coding, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC). [0071] The entropy encoding module 165 may encode a variety of information, such as residual value coefficient information and block type information of the coding unit, prediction mode information, partition unit information, prediction unit information, transform unit information, motion vector information, reference frame information, block interpolation information, filtering information, etc. from the rearrangement module 160 and the prediction modules 120 and 125. [0072] The entropy encoding module 165 may entropy encode the coefficients of the coding unit input from the rearrangement module 160. [0073] The inverse quantization module 140 may inversely quantize the values quantized by the quantization module 135 and the inverse transform module 145 may inversely transform the values transformed by the transform module 130. The residual value generated by the inverse quantization module 140 and the inverse transform module 145 may be combined with the prediction unit predicted by a motion estimation module, a motion compensation module, and the intra prediction module of the prediction modules 120 and 125 such that a reconstructed block can be generated. [0074] The filter module 150 may include at least one of a deblocking filter, an offset correction unit, and an adaptive loop filter (ALF). [0075] The deblocking filter may remove block distortion that occurs due to boundaries between the blocks in the reconstructed picture. In order to determine whether to perform deblocking, the pixels included in several rows or columns in the block may be a basis of determining whether to apply the deblocking filter to the current block. When the deblocking filter is applied to the block, a strong filter or a weak filter may be applied depending on required deblocking filtering strength. Also, in applying the deblocking filter, horizontal direction filtering and vertical direction filtering may be processed in parallel. [0076] The offset correction module may correct offset with the original picture in a unit of a pixel in the picture subjected to deblocking. In order to perform the offset correction on a particular picture, it is possible to use a method of applying offset in consideration of edge information of each pixel or a method of partitioning pixels of a picture into the predetermined number of regions, determining a region to be subjected to perform offset, and applying the offset to the determined region. [0077] Adaptive loop filtering (ALF) may be performed based on the value obtained by comparing the filtered reconstructed picture and the original picture. The pixels included in the picture may be divided into predetermined groups, a filter to be applied to each of the groups may be determined, and filtering may be individually performed for each group. Information on whether to apply ALF and a luma signal may be transmitted by coding units (CU) . The shape and filter coefficient of a filter for ALF may vary depending on each block. Also, the filter for ALF in the same shape (fixed shape) may be applied regardless of characteristics of the application target block. [0078] The memory 155 may store the reconstructed block or picture calculated through the filter module 150. The stored reconstructed block or picture may be provided to the prediction modules 120 and 125 in performing inter prediction. [0079] FIG. 2 is a block diagram illustrating a device for decoding a video according to an embodiment of the present invention. [0080] Referring to FIG. 2, the device 200 for decoding a video may include: an entropy decoding module 210, a rearrangement module 215, an inverse quantization module 220, an inverse transform module 225, prediction modules 230 and 235, a filter module 24 0, and a memory 24 5. [0081] When a video bitstream is input from the device for encoding a video, the input bitstream may be decoded according to an inverse process of the device for encoding a video. [0082] The entropy decoding module 210 may perform entropy decoding according to an inverse process of entropy encoding by the entropy encoding module of the device for encoding a video. For example, corresponding to the methods performed by the device for encoding a video, various methods, such as exponential Golomb coding, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC) may be applied. [0083] The entropy decoding module 210 may decode information on intra prediction and inter prediction performed by the device for encoding a video. [0084] The rearrangement module 215 may perform rearrangement on the bitstream entropy decoded by the entropy decoding module 210 based on the rearrangement method used in the device for encoding a video. The rearrangement module may reconstruct and rearrange the coefficients in the form of one-dimensional vectors to the coefficient in the form of two-dimensional blocks. The rearrangement module 215 may receive information related to coefficient scanning performed in the device for encoding a video and may perform rearrangement via a method of inversely scanning the coefficients based on the scanning order performed in the device for encoding a video. [0085] The inverse quantization module 220 may perform inverse quantization based on a quantization parameter received from the device for encoding a video and the rearranged coefficients of the block. [0086] The inverse transform module 225 may perform the inverse transform, i.e., inverse DCT, inverse DST, and inverse KLT, which is the inverse process of transform, i.e., DCT, DST, and KLT, performed by the transform module on the quantization result by the device for encoding a video. Inverse transform may be performed based on a transfer unit determined by the device for encoding a video. The inverse transform module 225 of the device for decoding a video may selectively perform transform schemes (e.g., DCT, DST, and KLT) depending on multiple pieces of information, such as the prediction method, the size of the current block, the prediction direction, etc. [0087] The prediction modules 230 and 235 may generate a prediction block based on information on prediction block generation received from the entropy decoding module 210 and previously decoded block or picture information received from the memory 245. [0088] As described above, like the operation of the device for encoding a video, in performing intra prediction, when the size of the prediction unit is the same as the size of the transform unit, intra prediction may be performed on the prediction unit based on the pixels positioned at the left, the top left, and the top of the prediction unit. In performing intra prediction, when the size of the prediction unit is different from the size of the transform unit, intra prediction may be performed using a reference pixel based on the transform unit. Also, intra prediction using NxN partitioning may be used for only the smallest coding unit. [0089] The prediction modules 230 and 235 may include a prediction unit determination module, an inter prediction module, and an intra prediction module. The prediction unit determination module may receive a variety of information, such as prediction unit information, prediction mode information of an intra prediction method, information on motion prediction of an inter prediction method, etc. from the entropy decoding module 210, may divide a current coding unit into prediction units, and may determine whether inter prediction or intra prediction is performed on the prediction unit. By using information required in inter prediction of the current prediction unit received from the device for encoding a video, the inter prediction module 230 may perform inter prediction on the current prediction unit based on information of at least one of a previous picture or a subsequent picture of the current picture including the current prediction unit. Alternatively, inter prediction may be performed based on information of some pre-reconstructed regions in the current picture including the current prediction unit. [0090] In order to perform inter prediction, it may be determined for the coding unit which of a skip mode, a merge mode, an AMVP mode, and an inter block copy mode is used as the motion prediction method of the prediction unit included in the coding unit. [0091] The intra prediction module 235 may generate a prediction block based on pixel information in the current picture. When the prediction unit is a prediction unit subjected to intra prediction, intra prediction may be performed based on intra prediction mode information of the prediction unit received from the device for encoding a video. The intra prediction module 235 may include an adaptive intra smoothing (AIS) filter, a reference pixel interpolation module, and a DC filter. The AIS filter performs filtering on the reference pixel of the current block, and whether to apply the filter may be determined depending on the prediction mode of the current prediction unit. AIS filtering may be performed on the reference pixel of the current block by using the prediction mode of the prediction unit and AIS filter information received from the device for encoding a video. When the prediction mode of the current block is a mode where AIS filtering is not performed, the AIS filter may not be applied. [0092] When the prediction mode of the prediction unit is a prediction mode in which intra prediction is performed based on the pixel value obtained by interpolating the reference pixel, the reference pixel interpolation module may interpolate the reference pixel to generate the reference pixel of an integer pixel or less than an integer pixel. When the prediction mode of the current prediction unit is a prediction mode in which a prediction block is generated without interpolation the reference pixel, the reference pixel may not be interpolated. The DC filter may generate a prediction block through filtering when the prediction mode of the current block is a DC mode. [0093] The reconstructed block or picture may be provided to the filter module 240. The filter module 240 may include the deblocking filter, the offset correction module, and the ALF. [0094] Information on whether or not the deblocking filter is applied to the corresponding block or picture and information on which of a strong filter and a weak filter is applied when the deblocking filter is applied may be received from the device for encoding a video. The deblocking filter of the device for decoding a video may receive information on the deblocking filter from the device for encoding a video, and may perform deblocking filtering on the corresponding block. [0095] The offset correction module may perform offset correction on the reconstructed picture based on the type of offset correction and offset value information applied to a picture in performing encoding. [0096] The ALF may be applied to the coding unit based on information on whether to apply the ALF, ALF coefficient information, etc. received from the device for encoding a video. The ALF information may be provided as being included in a particular parameter set. [0097] The memory 245 may store the reconstructed picture or block for use as a reference picture or block, and may provide the reconstructed picture to an output module. [0098] As described above, in the embodiment of the present invention, for convenience of explanation, the coding unit is used as a term representing a unit for encoding, but the coding unit may serve as a unit performing decoding as well as encoding. [0099] In addition, a current block may represent a target block to be encoded/decoded. And, the current block may represent a coding tree block (or a coding tree unit), a coding block (or a coding unit), a transform block (or a transform unit), a prediction block (or a prediction unit), or the like depending on an encoding/decoding step. [00100] A picture may be encoded/decoded by divided into base blocks having a square shape or a non-square shape. At this time, the base block may be referred to as a coding tree unit. The coding tree unit may be defined as a coding unit of the largest size allowed within a sequence or a slice. Information regarding whether the coding tree unit has a square shape or has a non-square shape or information regarding a size of the coding tree unit may be signaled through a sequence parameter set, a picture parameter set, or a slice header. The coding tree unit may be divided into smaller size partitions. At this time, if it is assumed that a depth of a partition generated by dividing the coding tree unit is 1, a depth of a partition generated by dividing the partition having depth 1 may be defined as 2. That is, a partition generated by dividing a partition having a depth k in the coding tree unit may be defined as having a depth k+1. [00101] A partition of arbitrary size generated by dividing a coding tree unit may be defined as a coding unit. The coding unit may be recursively divided or divided into base units for performing prediction, quantization, transform, or in-loop filtering, and the like. For example, a partition of arbitrary size generated by dividing the coding unit may be defined as a coding unit, or may be defined as a transform unit or a prediction unit, which is a base unit for performing prediction, quantization, transform or in-loop filtering and the like. [00102] Partitioning of a coding tree unit or a coding unit may be performed based on at least one of a vertical line and a horizontal line. In addition, the number of vertical lines or horizontal lines partitioning the coding tree unit or the coding unit may be at least one or more. For example, the coding tree unit or the coding unit may be divided into two partitions using one vertical line or one horizontal line, or the coding tree unit or the coding unit may be divided into three partitions using two vertical lines or two horizontal lines. Alternatively, the coding tree unit or the coding unit may be partitioned into four partitions having a length and a width of 1/2 by using one vertical line and one horizontal line. [00103] When a coding tree unit or a coding unit is divided into a plurality of partitions using at least one vertical line or at least one horizontal line, the partitions may have a uniform size or a different size. Alternatively, any one partition may have a different size from the remaining partitions. [00104] In the embodiments described below, it is assumed that a coding tree unit or a coding unit is divided into a quad tree structure or a binary tree structure. However, it is also possible to divide a coding tree unit or a coding unit using a larger number of vertical lines or a larger number of horizontal lines. [00105] FIG. 3 is a diagram illustrating an example of hierarchically partitioning a coding block based on a tree structure according to an embodiment of the present invention. [00106] An input video signal is decoded in predetermined block units. Such a default unit for decoding the input video signal is a coding block. The coding block may be a unit performing intra/inter prediction, transform, and quantization. In addition, a prediction mode (e.g., intra prediction mode or inter prediction mode) is determined in a unit of a coding block, and the prediction blocks included in the coding block may share the determined prediction mode. The coding block may be a square or non-square block having an arbitrary size in a range of 8x8 to 64x64, or may be a square or non-square block having a size of 128x128, 256x256, or more. [00107] Specifically, the coding block may be hierarchically partitioned based on at least one of a quad tree and a binary tree. Here, quad tree-based partitioning may mean that a 2Nx2N coding block is partitioned into four NxN coding blocks, and binary tree-based partitioning may mean that one coding block is partitioned into two coding blocks. Even if the binary tree-based partitioning is performed, a square-shaped coding block may exist in the lower depth. [00108] Binary tree-based partitioning may be symmetrically or asymmetrically performed. The coding block partitioned based on the binary tree may be a square block or a non-square block, such as a rectangular shape. For example, a partition type in which the binary tree-based partitioning is allowed may comprise at least one of a symmetric type of 2NxN (horizontal directional non-square coding unit) or Nx2N (vertical direction non-square coding unit), asymmetric type of nLx2N, nRx2N, 2NxnU, or 2NxnD. [00109] Binary tree-based partitioning may be limitedly allowed to one of a symmetric or an asymmetric type partition. In this case, constructing the coding tree unit with square blocks may correspond to quad tree CU partitioning, and constructing the coding tree unit with symmetric non-square blocks may correspond to binary tree partitioning. Constructing the coding tree unit with square blocks and symmetric non-square blocks may correspond to quad and binary tree CU partitioning. [00110] Binary tree-based partitioning may be performed on a coding block where quad tree-based partitioning is no longer performed. Quad tree-based partitioning may no longer be performed on the coding block partitioned based on the binary tree. [00111] Furthermore, partitioning of a lower depth may be determined depending on a partition type of an upper depth. For example, if binary tree-based partitioning is allowed in two or more depths, only the same type as the binary tree partitioning of the upper depth may be allowed in the lower depth. For example, if the binary tree-based partitioning in the upper depth is performed with 2NxN type, the binary tree-based partitioning in the lower depth is also performed with 2NxN type. Alternatively, if the binary tree-based partitioning in the upper depth is performed with Nx2N type, the binary tree-based partitioning in the lower depth is also performed with Nx2N type. [00112] On the contrary, it is also possible to allow, in a lower depth, only a type different from a binary tree partitioning type of an upper depth. [00113] It may be possible to limit only a specific type of binary tree based partitioning to be used for sequence, slice, coding tree unit, or coding unit. As an example, only 2NxN type or Nx2N type of binary tree-based partitioning may be allowed for the coding tree unit. An available partition type may be predefined in an encoder or a decoder. Or information on available partition type or on unavailable partition type on may be encoded and then signaled through a bitstream. [00114] FIG. 5 is a diagram illustrating an example in which only a specific type of binary tree-based partitioning is allowed. FIG. 5A shows an example in which only Nx2N type of binary tree-based partitioning is allowed, and FIG. 5B shows an example in which only 2NxN type of binary tree-based partitioning is allowed. In order to implement adaptive partitioning based on the quad tree or binary tree, information indicating quad tree-based partitioning, information on the size/depth of the coding block that quad tree-based partitioning is allowed, information indicating binary tree-based partitioning, information on the size/depth of the coding block that binary tree-based partitioning is allowed, information on the size/depth of the coding block that binary tree-based partitioning is not allowed, information on whether binary tree-based partitioning is performed in a vertical direction or a horizontal direction, etc. may be used. [00115] In addition, information on the number of times a binary tree partitioning is allowed, a depth at which the binary tree partitioning is allowed, or the number of the depths at which the binary tree partitioning is allowed may be obtained for a coding tree unit or a specific coding unit. The information may be encoded in a unit of a coding tree unit or a coding unit, and may be transmitted to a decoder through a bitstream. [00116] For example, a syntax 'max_binary_depth_idx_minusl' indicating a maximum depth at which binary tree partitioning is allowed may be encoded / decoded through a bitstream. In this case, max_binary_depth_idx_minusl + 1 may indicate the maximum depth at which the binary tree partitioning is allowed. [00117] Referring to the example shown in FIG. 6, in FIG. 6, the binary tree partitioning has been performed for a coding unit having a depth of 2 and a coding unit having a depth of 3. Accordingly, at least one of information indicating the number of times the binary tree partitioning in the coding tree unit has been performed (i.e., 2 times), information indicating the maximum depth which the binary tree partitioning has been allowed in the coding tree unit (i.e., depth 3) , or the number of depths in which the binary tree partitioning has been performed in the coding tree unit (i.e., 2 (depth 2 and depth 3)) may be encoded / decoded through a bitstream. [00118] As another example, at least one of information on the number of times the binary tree partitioning is permitted, the depth at which the binary tree partitioning is allowed, or the number of the depths at which the binary tree partitioning is allowed may be obtained for each sequence or each slice. For example, the information may be encoded in a unit of a sequence, a picture, or a slice unit and transmitted through a bitstream. Accordingly, at least one of the number of the binary tree partitioning in a first slice, the maximum depth in which the binary tree partitioning is allowed in the first slice, or the number of depths in which the binary tree partitioning is performed in the first slice may be difference from a second slice. For example, in the first slice, binary tree partitioning may be permitted for only one depth, while in the second slice, binary tree partitioning may be permitted for two depths. [00119] As another example, the number of times the binary tree partitioning is permitted, the depth at which the binary tree partitioning is allowed, or the number of depths at which the binary tree partitioning is allowed may be set differently according to a time level identifier (TemporallD) of a slice or a picture. Here, the temporal level identifier (TemporallD) is used to identify each of a plurality of layers of video having a scalability of at least one of view, spatial, temporal or quality. [00120] As shown in FIG. 3, the first coding block 300 with the partition depth (split depth) of k may be partitioned into multiple second coding blocks based on the quad tree. For example, the second coding blocks 310 to 340 may be square blocks having the half width and the half height of the first coding block, and the partition depth of the second coding block may be increased to k+1. [00121] The second coding block 310 with the partition depth of k+1 may be partitioned into multiple third coding blocks with the partition depth of k+2. Partitioning of the second coding block 310 may be performed by selectively using one of the quad tree and the binary tree depending on a partitioning method. Here, the partitioning method may be determined based on at least one of the information indicating quad tree-based partitioning and the information indicating binary tree-based partitioning. [00122] When the second coding block 310 is partitioned based on the quad tree, the second coding block 310 may be partitioned into four third coding blocks 310a having the half width and the half height of the second coding block, and the partition depth of the third coding block 310a may be increased to k+2. In contrast, when the second coding block 310 is partitioned based on the binary tree, the second coding block 310 may be partitioned into two third coding blocks. Here, each of two third coding blocks may be a non-square block having one of the half width and the half height of the second coding block, and the partition depth may be increased to k+2. The second coding block may be determined as a non-square block of a horizontal direction or a vertical direction depending on a partitioning direction, and the partitioning direction may be determined based on the information on whether binary tree-based partitioning is performed in a vertical direction or a horizontal direction. [00123] In the meantime, the second coding block 310 may be determined as a leaf coding block that is no longer partitioned based on the quad tree or the binary tree. In this case, the leaf coding block may be used as a prediction block or a transform block. [00124] Like partitioning of the second coding block 310, the third coding block 310a may be determined as a leaf coding block, or may be further partitioned based on the quad tree or the binary tree. [00125] In the meantime, the third coding block 310b partitioned based on the binary tree may be further partitioned into coding blocks 310b-2 of a vertical direction or coding blocks 310b-3 of a horizontal direction based on the binary tree, and the partition depth of the relevant coding blocks may be increased to k+3. Alternatively, the third coding

I/We Claim:
1. A method for decoding a video, the method comprising:
determining whether to split a parent node coding block based on quad-tree
partitioning;
determining whether to split the parent node coding block based on binarytree partitioning when it is determined that the parent node coding block is not split
based on the quad-tree partitioning;
splitting the parent node coding block into two non-square coding blocks of
the same size by applying horizontal binary-tree partitioning or vertical binary-tree
10 partitioning when it is determined to split the parent node coding block based on
the binary-tree partitioning;
determining whether to split one of the non-square coding blocks into two
partitions or not; and
splitting the non-square coding block into two partitions by applying either
the horizontal binary-tree partitioning or the vertical binary-tree partitioning when
it is determined to split the non-square coding block,
wherein when the parent node coding block is split based on the horizontal
binary-tree partitioning, the horizontal binary-tree partitioning is determined not to
be allowed to the non-square coding block,
wherein when the parent node coding block is split based on the vertical
binary-tree partitioning, the vertical binary-tree partitioning is determined not to be
allowed to the non-square coding block, and
wherein the parent node coding block has a size of 128x128.
2. The method of claim 1, wherein the method further comprises decoding size
information specifying a size of a merge process region, and
wherein if both the non-square coding blocks are included in the same merge
processing region, one of the non-square coding blocks is not available as a merge
candidate for the other of the non-square coding blocks.

3. A method for encoding a video, the method comprising:
determining whether to split a parent node coding block based on quad-tree
partitioning;
determining whether to split the parent node coding block based on binary tree partitioning when it is determined that the parent node coding block is not split
based on the quad-tree partitioning;
splitting the parent node coding block into two non-square coding blocks of
the same size by applying horizontal line binary-tree partitioning or vertical binarytree partitioning when it is determined to split the parent node coding block based
on the binary-tree partitioning; and
determining whether to split one of the non-square coding blocks into two
partitions or not; and
splitting the non-square coding block into two partitions by applying either
the horizontal binary-tree partitioning or the vertical binary-tree partitioning when
it is determined to split the non-square coding block,
wherein when the parent node coding block is split based on the horizontal
binary-tree partitioning, the horizontal binary-tree partitioning is determined not to
be allowed to the non-square coding block,
wherein when the parent node coding block is split based on the vertical
binary-tree partitioning, the vertical binary-tree partitioning is determined not to be
allowed to the non-square coding block, and
wherein the parent node coding block has a size of 128x128.
4. The method of claim 3, wherein the method further comprises determining
a size of a merge processing region, and
wherein if both the non-square coding blocks are included in the same merge
processing region, one of the non-square coding blocks is not available as a merge
candidate for the other of the non-square coding blocks.
5. An apparatus (100) for encoding a video, the apparatus comprising:
a picture partitioning unit (110) to:
determine whether to split a parent node coding block based on quad-tree
partitioning,
determine whether to split the parent node coding block based on binarytree partitioning when it is determined that the parent node coding block is not split
based on the quad-tree partitioning,
split the parent node coding block into two non-square coding blocks of the
same size by applying horizontal binary-tree partitioning or vertical binary-tree
partitioning when it is determined to split the parent node coding block based on
the binary-tree partitioning,
determine whether to split one of the non-square coding blocks into two
partitions or not, and
split the non-square coding block into two partitions by applying either the
horizontal binary-tree partitioning or the vertical binary-tree partitioning when it is
determined to split the non-square coding block,
wherein when the parent node coding block is split based on the horizontal
binary-tree partitioning, the horizontal binary-tree partitioning is determined not to
be allowed to the non-square coding block,
wherein when the parent node coding block is split based on the vertical
binary-tree partitioning, the vertical binary-tree partitioning is determined not to be
allowed to the non-square coding block, and
wherein the parent node coding block has a size of 128x128.

This is a Divisional Application of Parent/Original Application 201917002143 Dated 17 January 2019
DESCRIPTION
Technical Field
[0001] The present invention relates to a method
and an apparatus for processing video signal.
Background Art
[0002] Recently, demands for high-resolution and high-quality images such as high definition (HD) images and ultra-high definition (UHD) images have increased in various application fields. However, higher resolution and quality image data has increasing amounts of data in comparison with conventional image data. Therefore, when transmitting image data by using a medium such as conventional wired and wireless broadband networks, or when storing image data by using a conventional storage medium, costs of transmitting and storing increase. In order to solve these problems occurring with an increase in resolution and quality of image data, high-efficiency image encoding/decoding techniques may be utilized. [0003] Image compression technology includes various techniques, including: an inter-prediction technique of predicting a pixel value included in a current picture from a previous or subsequent picture of the current picture; an intra-prediction technique of predicting a pixel value included in a current picture by using pixel information in the current picture; an entropy encoding technique of assigning a short code to a value with a high appearance frequency and assigning a long code to a value with a low appearance frequency; etc. Image data may be effectively compressed by using such image compression

technology, and may be transmitted or stored. [0004] In the meantime, with demands for high-resolution images, demands for stereographic image content, which is a new image service, have also increased. A video compression technique for effectively providing stereographic image content with high resolution and ultra-high resolution is being discussed.
Disclosure Technical Problem
[0005] An object of the present invention is to provide a method and an apparatus for efficiently performing inter prediction for an encoding/decoding target block in encoding/decoding a video signal. [0006] An object of the present invention is to provide a method and an apparatus for deriving a merge candidate based on a block having a pre-determined shape or a pre-determined size in encoding/decoding a video signal.
[0007] An object of the present invention is to provide a method and an apparatus for performing a merge in parallel in a unit of a pre-determined shape or a pre-determined size in encoding/decoding a video signal.
[0008] The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems. And, other technical problems that are not mentioned will be apparently understood to those skilled in the art from the following description.
Technical Solution
[0009] A method and an apparatus for decoding a video signal according to the present invention may derive a spatial merge candidate for a current block,

generate a merge candidate list for the current block based on the spatial merge candidate, obtain motion information for the current block based on the merge candidate list, and perform motion compensation for the current block using the motion information. [0010] A method and an apparatus for encoding a video signal according to the present invention may derive a spatial merge candidate for a current block, generate a merge candidate list for the current block based on the spatial merge candidate, obtain motion information for the current block based on the merge candidate list, and perform motion compensation for the current block using the motion information. [0011] In the method and the apparatus for encoding/decoding a video signal according to the present invention, if the current block does not have a pre-defined shape or does not have a size equal to or greater than a pre-defined size, the spatial merge candidate of the current block may be derived based on a block having the pre-defined shape or having a size equal to or greater than the pre-defined size, the block comprising the current block.
[0012] In the method and the apparatus for encoding/decoding a video signal according to the present invention, the pre-defined shape may be a square shape.
[0013] In the method and the apparatus for encoding/decoding a video signal according to the present invention, the current block may have a same spatial merge candidate as a neighboring block included in the block of the square shape with the current block.
[0014] In the method and the apparatus for encoding/decoding a video signal according to the present invention, if the current block and the spatial merge candidate are included in a same merge estimation

region, the spatial merge candidate may be determined to be unavailable.
[0015] In the method and the apparatus for encoding/decoding a video signal according to the present invention, the merge estimation region may have a square shape or a non-square shape.
[0016] In the method and the apparatus for encoding/decoding a video signal according to the present invention, if the merge estimation region has the non-square shape, a number of candidate shapes of merge candidates that the merge estimation region is able to have may be restricted by a pre-defined number.
[0017] The features briefly summarized above for the present invention are only illustrative aspects of the detailed description of the invention that follows, but do not limit the scope of the invention.
Advantageous Effects
[0018] According to the present invention, an efficient inter prediction may be performed for an encoding/decoding target block.
[0019] According to the present invention, a merge candidate may be derived based on a block having a pre¬determined shape or a pre-determined size.
[0020] According to the present invention, a merge can be performed in parallel in a unit of a pre¬determined shape or a pre-determined size.
[0021] According to the present invention, intra prediction for an encoding/decoding target block may be performed by selecting at least one of a plurality of reference lines.
[0022] According to the present invention, a reference line may be derived based on a block having a pre-determined shape or having a size equal to or greater than a pre-determined size.
[0023] According to the present invention, an

intra filter may be applied to at least one of a plurality of reference lines.
[0024] According to the present invention, an intra prediction mode or a number of the intra prediction mode may be adaptively determined according to a reference line used for intra prediction of a current block.
[0025] The effects obtainable by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the description below.
Description of Drawings
[0026] FIG. 1 is a block diagram illustrating a device for encoding a video according to an embodiment of the present invention.
[0027] FIG. 2 is a block diagram illustrating a device for decoding a video according to an embodiment of the present invention.
[0028] FIG. 3 is a diagram illustrating an example of hierarchically partitioning a coding block based on a tree structure according to an embodiment of the present invention.
[0029] FIG. 4 is a diagram illustrating a partition type in which binary tree-based partitioning is allowed according to an embodiment of the present invention.
[0030] FIG. 5 is a diagram illustrating an example in which only a binary tree-based partition of a pre¬determined type is allowed according to an embodiment of the present invention.
[0031] FIG. 6 is a diagram for explaining an example in which information related to the allowable number of binary tree partitioning is encoded/decoded, according to an embodiment to which the present

invention is applied.
[0032] FIG. 7 is a diagram illustrating a partition mode applicable to a coding block according to an embodiment of the present invention. [0033] FIG. 8 is a flowchart illustrating an inter prediction method according to an embodiment of the present invention.
[0034] FIG. 9 is a diagram illustrating a process of deriving motion information of a current block when a merge mode is applied to a current block. [0035] FIG. 10 illustrates a process of deriving motion information of a current block when an AMVP mode is applied to the current block.
[0036] FIG. 11 is a diagram showing a spatial merge candidate of a current block.
[0037] FIG. 12 is a diagram showing a co-located block of a current block.
[0038] FIG. 13 is a diagram for explaining an example of obtaining a motion vector of a temporal merge candidate by scaling a motion vector of a co-located block.
[0039] FIG. 14 is a diagram showing an example of deriving a merge candidate of a non-square block on the basis of a square block.
[0040] FIG. 15 is a diagram for explaining an example in which a merge candidate of a binary-tree partitioned block is derived based on an upper node block.
[0041] FIG. 16 is a diagram illustrating an example of determining availability of a spatial merge candidate according to a merge estimation region. [0042] FIG. 17 is a flowchart illustrating processes of obtaining a residual sample according to an embodiment to which the present invention is applied.

Mode for Invention
[0043] A variety of modifications may be made to the present invention and there are various embodiments of the present invention, examples of which will now be provided with reference to drawings and described in detail. However, the present invention is not limited thereto, and the exemplary embodiments can be construed as including all modifications, equivalents, or substitutes in a technical concept and a technical scope of the present invention. The similar reference numerals refer to the similar element in described the drawings.
[0044] Terms used in the specification, 'first',
'second' , etc. can be used to describe various components, but the components are not to be construed as being limited to the terms. The terms are only used to differentiate one component from other components. For example, the 'first' component may be named the 'second' component without departing from the scope of the present invention, and the 'second' component may also be similarly named the 'first' component. The term 'and/or' includes a combination of a plurality of items or any one of a plurality of terms.
[0045] It will be understood that when an element is simply referred to as being 'connected to' or
'coupled to' another element without being 'directly connected to' or 'directly coupled to' another element in the present description, it may be 'directly connected to' or 'directly coupled to' another element or be connected to or coupled to another element, having the other element intervening therebetween. In contrast, it should be understood that when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements present.

[0046] The terms used in the present specification are merely used to describe particular embodiments, and are not intended to limit the present invention. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. In the present specification, it is to be understood that terms such as "including", "having", etc. are intended to indicate the existence of the features, numbers, steps, actions, elements, parts, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, numbers, steps, actions, elements, parts, or combinations thereof may exist or may be added.
[0047] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same constituent elements in the drawings are denoted by the same reference numerals, and a repeated description of the same elements will be omitted. [0048] FIG. 1 is a block diagram illustrating a device for encoding a video according to an embodiment of the present invention.
[0049] Referring to FIG. 1, the device 100 for encoding a video may include: a picture partitioning module 110, prediction modules 120 and 125, a transform module 130, a quantization module 135, a rearrangement module 160, an entropy encoding module 165, an inverse quantization module 140, an inverse transform module 145, a filter module 150, and a memory 155.
[0050] The constitutional parts shown in FIG. 1 are independently shown so as to represent characteristic functions different from each other in the device for encoding a video. Thus, it does not

mean that each constitutional part is constituted in a constitutional unit of separated hardware or software. In other words, each constitutional part includes each of enumerated constitutional parts for convenience. Thus, at least two constitutional parts of each constitutional part may be combined to form one constitutional part or one constitutional part may be divided into a plurality of constitutional parts to perform each function. The embodiment where each constitutional part is combined and the embodiment where one constitutional part is divided are also included in the scope of the present invention, if not departing from the essence of the present invention. [0051] Also, some of constituents may not be indispensable constituents performing essential functions of the present invention but be selective constituents improving only performance thereof. The present invention may be implemented by including only the indispensable constitutional parts for implementing the essence of the present invention except the constituents used in improving performance. The structure including only the indispensable constituents except the selective constituents used in improving only performance is also included in the scope of the present invention.
[0052] The picture partitioning module 110 may partition an input picture into one or more processing units. Here, the processing unit may be a prediction unit (PU) , a transform unit (TU) , or a coding unit (CU). The picture partitioning module 110 may partition one picture into combinations of multiple coding units, prediction units, and transform units, and may encode a picture by selecting one combination of coding units, prediction units, and transform units with a predetermined criterion (e.g., cost function). [0053] For example, one picture may be partitioned

into multiple coding units. A recursive tree structure, such as a quad tree structure, may be used to partition a picture into coding units. A coding unit which is partitioned into other coding units with one picture or a largest coding unit as a root may be partitioned with child nodes corresponding to the number of partitioned coding units. A coding unit which is no longer partitioned by a predetermined limitation serves as a leaf node. That is, when it is assumed that only square partitioning is possible for one coding unit, one coding unit may be partitioned into four other coding units at most.
[0054] Hereinafter, in the embodiment of the present invention, the coding unit may mean a unit performing encoding, or a unit performing decoding. [0055] A prediction unit may be one of partitions partitioned into a square or a rectangular shape having the same size in a single coding unit, or a prediction unit may be one of partitions partitioned so as to have a different shape / size in a single coding unit.
[0056] When a prediction unit subjected to intra prediction is generated based on a coding unit and the coding unit is not the smallest coding unit, intra prediction may be performed without partitioning the coding unit into multiple prediction units NxN. [0057] The prediction modules 120 and 125 may include an inter prediction module 120 performing inter prediction and an intra prediction module 125 performing intra prediction. Whether to perform inter prediction or intra prediction for the prediction unit may be determined, and detailed information (e.g., an intra prediction mode, a motion vector, a reference picture, etc.) according to each prediction method may be determined. Here, the processing unit subjected to prediction may be different from the processing unit

for which the prediction method and detailed content is determined. For example, the prediction method, the prediction mode, etc. may be determined by the prediction unit, and prediction may be performed by the transform unit. A residual value (residual block) between the generated prediction block and an original block may be input to the transform module 130. Also, prediction mode information, motion vector information, etc. used for prediction may be encoded with the residual value by the entropy encoding module 165 and may be transmitted to a device for decoding a video. When a particular encoding mode is used, it is possible to transmit to a device for decoding video by encoding the original block as it is without generating the prediction block through the prediction modules 120 and 125.
[0058] The inter prediction module 120 may predict the prediction unit based on information of at least one of a previous picture or a subsequent picture of the current picture, or may predict the prediction unit based on information of some encoded regions in the current picture, in some cases. The inter prediction module 120 may include a reference picture interpolation module, a motion prediction module, and a motion compensation module.
[0059] The reference picture interpolation module may receive reference picture information from the memory 155 and may generate pixel information of an integer pixel or less then the integer pixel from the reference picture. In the case of luma pixels, an 8-tap DCT-based interpolation filter having different filter coefficients may be used to generate pixel information of an integer pixel or less than an integer pixel in a unit of a 1/4 pixel. In the case of chroma signals, a 4-tap DCT-based interpolation filter having different filter coefficient may be used

to generate pixel information of an integer pixel or less than an integer pixel in a unit of a 1/8 pixel. [0060] The motion prediction module may perform motion prediction based on the reference picture interpolated by the reference picture interpolation module. As methods for calculating a motion vector, various methods, such as a full search-based block matching algorithm (FBMA), a three step search (TSS), a new three-step search algorithm (NTS), etc., may be used. The motion vector may have a motion vector value in a unit of a 1/2 pixel or a 1/4 pixel based on an interpolated pixel. The motion prediction module may predict a current prediction unit by changing the motion prediction method. As motion prediction methods, various methods, such as a skip method, a merge method, an AMVP (Advanced Motion Vector Prediction) method, an intra block copy method, etc., may be used.
[0061] The intra prediction module 125 may generate a prediction unit based on reference pixel information neighboring to a current block which is pixel information in the current picture. When the neighboring block of the current prediction unit is a block subjected to inter prediction and thus a reference pixel is a pixel subjected to inter prediction, the reference pixel included in the block subjected to inter prediction may be replaced with reference pixel information of a neighboring block subjected to intra prediction. That is, when a reference pixel is not available, at least one reference pixel of available reference pixels may be used instead of unavailable reference pixel information.
[0062] Prediction modes in intra prediction may include a directional prediction mode using reference pixel information depending on a prediction direction

and a non-directional prediction mode not using directional information in performing prediction. A mode for predicting luma information may be different from a mode for predicting chroma information, and in order to predict the chroma information, intra prediction mode information used to predict luma information or predicted luma signal information may be utilized.
[0063] In performing intra prediction, when the size of the prediction unit is the same as the size of the transform unit, intra prediction may be performed on the prediction unit based on pixels positioned at the left, the top left, and the top of the prediction unit. However, in performing intra prediction, when the size of the prediction unit is different from the size of the transform unit, intra prediction may be performed using a reference pixel based on the transform unit. Also, intra prediction using NxN partitioning may be used for only the smallest coding unit.
[0064] In the intra prediction method, a prediction block may be generated after applying an AIS (Adaptive Intra Smoothing) filter to a reference pixel depending on the prediction modes. The type of the AIS filter applied to the reference pixel may vary. In order to perform the intra prediction method, an intra prediction mode of the current prediction unit may be predicted from the intra prediction mode of the prediction unit neighboring to the current prediction unit. In prediction of the prediction mode of the current prediction unit by using mode information predicted from the neighboring prediction unit, when the intra prediction mode of the current prediction unit is the same as the intra prediction mode of the neighboring prediction unit, information indicating that the prediction modes of

the current prediction unit and the neighboring prediction unit are equal to each other may be transmitted using predetermined flag information. When the prediction mode of the current prediction unit is different from the prediction mode of the neighboring prediction unit, entropy encoding may be performed to encode prediction mode information of the current block.
[0065] Also, a residual block including information on a residual value which is a different between the prediction unit subjected to prediction and the original block of the prediction unit may be generated based on prediction units generated by the prediction modules 120 and 125. The generated residual block may be input to the transform module 130.
[0066] The transform module 130 may transform the residual block including the information on the residual value between the original block and the prediction unit generated by the prediction modules 120 and 125 by using a transform method, such as discrete cosine transform (DCT), discrete sine transform (DST) , and KLT. Whether to apply DCT, DST, or KLT in order to transform the residual block may be determined based on intra prediction mode information of the prediction unit used to generate the residual block.
[0067] The quantization module 135 may quantize values transformed to a frequency domain by the transform module 130. Quantization coefficients may vary depending on the block or importance of a picture. The values calculated by the quantization module 135 may be provided to the inverse quantization module 14 0 and the rearrangement module 160. [0068] The rearrangement module 160 may rearrange coefficients of quantized residual values.

[0069] The rearrangement module 160 may change a coefficient in the form of a two-dimensional block into a coefficient in the form of a one-dimensional vector through a coefficient scanning method. For example, the rearrangement module 160 may scan from a DC coefficient to a coefficient in a high frequency domain using a zigzag scanning method so as to change the coefficients to be in the form of one-dimensional vectors. Depending on the size of the transform unit and the intra prediction mode, vertical direction scanning where coefficients in the form of two-dimensional blocks are scanned in the column direction or horizontal direction scanning where coefficients in the form of two-dimensional blocks are scanned in the row direction may be used instead of zigzag scanning. That is, which scanning method among zigzag scanning, vertical direction scanning, and horizontal direction scanning is used may be determined depending on the size of the transform unit and the intra prediction mode.
[0070] The entropy encoding module 165 may perform entropy encoding based on the values calculated by the rearrangement module 160. Entropy encoding may use various encoding methods, for example, exponential Golomb coding, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC).
[0071] The entropy encoding module 165 may encode a variety of information, such as residual value coefficient information and block type information of the coding unit, prediction mode information, partition unit information, prediction unit information, transform unit information, motion vector information, reference frame information, block interpolation information, filtering information, etc. from the rearrangement module 160 and the prediction

modules 120 and 125.
[0072] The entropy encoding module 165 may entropy encode the coefficients of the coding unit input from the rearrangement module 160.
[0073] The inverse quantization module 140 may inversely quantize the values quantized by the quantization module 135 and the inverse transform module 145 may inversely transform the values transformed by the transform module 130. The residual value generated by the inverse quantization module 140 and the inverse transform module 145 may be combined with the prediction unit predicted by a motion estimation module, a motion compensation module, and the intra prediction module of the prediction modules 120 and 125 such that a reconstructed block can be generated.
[0074] The filter module 150 may include at least one of a deblocking filter, an offset correction unit, and an adaptive loop filter (ALF).
[0075] The deblocking filter may remove block distortion that occurs due to boundaries between the blocks in the reconstructed picture. In order to determine whether to perform deblocking, the pixels included in several rows or columns in the block may be a basis of determining whether to apply the deblocking filter to the current block. When the deblocking filter is applied to the block, a strong filter or a weak filter may be applied depending on required deblocking filtering strength. Also, in applying the deblocking filter, horizontal direction filtering and vertical direction filtering may be processed in parallel.
[0076] The offset correction module may correct offset with the original picture in a unit of a pixel in the picture subjected to deblocking. In order to perform the offset correction on a particular picture,

it is possible to use a method of applying offset in consideration of edge information of each pixel or a method of partitioning pixels of a picture into the predetermined number of regions, determining a region to be subjected to perform offset, and applying the offset to the determined region.
[0077] Adaptive loop filtering (ALF) may be performed based on the value obtained by comparing the filtered reconstructed picture and the original picture. The pixels included in the picture may be divided into predetermined groups, a filter to be applied to each of the groups may be determined, and filtering may be individually performed for each group. Information on whether to apply ALF and a luma signal may be transmitted by coding units (CU) . The shape and filter coefficient of a filter for ALF may vary depending on each block. Also, the filter for ALF in the same shape (fixed shape) may be applied regardless of characteristics of the application target block.
[0078] The memory 155 may store the reconstructed block or picture calculated through the filter module 150. The stored reconstructed block or picture may be provided to the prediction modules 120 and 125 in performing inter prediction.
[0079] FIG. 2 is a block diagram illustrating a device for decoding a video according to an embodiment of the present invention.
[0080] Referring to FIG. 2, the device 200 for decoding a video may include: an entropy decoding module 210, a rearrangement module 215, an inverse quantization module 220, an inverse transform module 225, prediction modules 230 and 235, a filter module 24 0, and a memory 24 5.
[0081] When a video bitstream is input from the device for encoding a video, the input bitstream may

be decoded according to an inverse process of the device for encoding a video.
[0082] The entropy decoding module 210 may perform entropy decoding according to an inverse process of entropy encoding by the entropy encoding module of the device for encoding a video. For example, corresponding to the methods performed by the device for encoding a video, various methods, such as exponential Golomb coding, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC) may be applied. [0083] The entropy decoding module 210 may decode information on intra prediction and inter prediction performed by the device for encoding a video. [0084] The rearrangement module 215 may perform rearrangement on the bitstream entropy decoded by the entropy decoding module 210 based on the rearrangement method used in the device for encoding a video. The rearrangement module may reconstruct and rearrange the coefficients in the form of one-dimensional vectors to the coefficient in the form of two-dimensional blocks. The rearrangement module 215 may receive information related to coefficient scanning performed in the device for encoding a video and may perform rearrangement via a method of inversely scanning the coefficients based on the scanning order performed in the device for encoding a video.
[0085] The inverse quantization module 220 may perform inverse quantization based on a quantization parameter received from the device for encoding a video and the rearranged coefficients of the block. [0086] The inverse transform module 225 may perform the inverse transform, i.e., inverse DCT, inverse DST, and inverse KLT, which is the inverse process of transform, i.e., DCT, DST, and KLT, performed by the transform module on the quantization

result by the device for encoding a video. Inverse transform may be performed based on a transfer unit determined by the device for encoding a video. The inverse transform module 225 of the device for decoding a video may selectively perform transform schemes (e.g., DCT, DST, and KLT) depending on multiple pieces of information, such as the prediction method, the size of the current block, the prediction direction, etc.
[0087] The prediction modules 230 and 235 may generate a prediction block based on information on prediction block generation received from the entropy decoding module 210 and previously decoded block or picture information received from the memory 245. [0088] As described above, like the operation of the device for encoding a video, in performing intra prediction, when the size of the prediction unit is the same as the size of the transform unit, intra prediction may be performed on the prediction unit based on the pixels positioned at the left, the top left, and the top of the prediction unit. In performing intra prediction, when the size of the prediction unit is different from the size of the transform unit, intra prediction may be performed using a reference pixel based on the transform unit. Also, intra prediction using NxN partitioning may be used for only the smallest coding unit.
[0089] The prediction modules 230 and 235 may include a prediction unit determination module, an inter prediction module, and an intra prediction module. The prediction unit determination module may receive a variety of information, such as prediction unit information, prediction mode information of an intra prediction method, information on motion prediction of an inter prediction method, etc. from the entropy decoding module 210, may divide a current

coding unit into prediction units, and may determine whether inter prediction or intra prediction is performed on the prediction unit. By using information required in inter prediction of the current prediction unit received from the device for encoding a video, the inter prediction module 230 may perform inter prediction on the current prediction unit based on information of at least one of a previous picture or a subsequent picture of the current picture including the current prediction unit. Alternatively, inter prediction may be performed based on information of some pre-reconstructed regions in the current picture including the current prediction unit.
[0090] In order to perform inter prediction, it may be determined for the coding unit which of a skip mode, a merge mode, an AMVP mode, and an inter block copy mode is used as the motion prediction method of the prediction unit included in the coding unit. [0091] The intra prediction module 235 may generate a prediction block based on pixel information in the current picture. When the prediction unit is a prediction unit subjected to intra prediction, intra prediction may be performed based on intra prediction mode information of the prediction unit received from the device for encoding a video. The intra prediction module 235 may include an adaptive intra smoothing (AIS) filter, a reference pixel interpolation module, and a DC filter. The AIS filter performs filtering on the reference pixel of the current block, and whether to apply the filter may be determined depending on the prediction mode of the current prediction unit. AIS filtering may be performed on the reference pixel of the current block by using the prediction mode of the prediction unit and AIS filter information received from the device for encoding a video. When the

prediction mode of the current block is a mode where AIS filtering is not performed, the AIS filter may not be applied.
[0092] When the prediction mode of the prediction unit is a prediction mode in which intra prediction is performed based on the pixel value obtained by interpolating the reference pixel, the reference pixel interpolation module may interpolate the reference pixel to generate the reference pixel of an integer pixel or less than an integer pixel. When the prediction mode of the current prediction unit is a prediction mode in which a prediction block is generated without interpolation the reference pixel, the reference pixel may not be interpolated. The DC filter may generate a prediction block through filtering when the prediction mode of the current block is a DC mode.
[0093] The reconstructed block or picture may be provided to the filter module 240. The filter module 240 may include the deblocking filter, the offset correction module, and the ALF.
[0094] Information on whether or not the deblocking filter is applied to the corresponding block or picture and information on which of a strong filter and a weak filter is applied when the deblocking filter is applied may be received from the device for encoding a video. The deblocking filter of the device for decoding a video may receive information on the deblocking filter from the device for encoding a video, and may perform deblocking filtering on the corresponding block.
[0095] The offset correction module may perform offset correction on the reconstructed picture based on the type of offset correction and offset value information applied to a picture in performing encoding.

[0096] The ALF may be applied to the coding unit based on information on whether to apply the ALF, ALF coefficient information, etc. received from the device for encoding a video. The ALF information may be provided as being included in a particular parameter set.
[0097] The memory 245 may store the reconstructed picture or block for use as a reference picture or block, and may provide the reconstructed picture to an output module.
[0098] As described above, in the embodiment of the present invention, for convenience of explanation, the coding unit is used as a term representing a unit for encoding, but the coding unit may serve as a unit performing decoding as well as encoding. [0099] In addition, a current block may represent a target block to be encoded/decoded. And, the current block may represent a coding tree block (or a coding tree unit), a coding block (or a coding unit), a transform block (or a transform unit), a prediction block (or a prediction unit), or the like depending on an encoding/decoding step.
[00100] A picture may be encoded/decoded by divided into base blocks having a square shape or a non-square shape. At this time, the base block may be referred to as a coding tree unit. The coding tree unit may be defined as a coding unit of the largest size allowed within a sequence or a slice. Information regarding whether the coding tree unit has a square shape or has a non-square shape or information regarding a size of the coding tree unit may be signaled through a sequence parameter set, a picture parameter set, or a slice header. The coding tree unit may be divided into smaller size partitions. At this time, if it is assumed that a depth of a partition generated by dividing the coding tree unit is 1, a depth of a

partition generated by dividing the partition having depth 1 may be defined as 2. That is, a partition generated by dividing a partition having a depth k in the coding tree unit may be defined as having a depth k+1.
[00101] A partition of arbitrary size generated by dividing a coding tree unit may be defined as a coding unit. The coding unit may be recursively divided or divided into base units for performing prediction, quantization, transform, or in-loop filtering, and the like. For example, a partition of arbitrary size generated by dividing the coding unit may be defined as a coding unit, or may be defined as a transform unit or a prediction unit, which is a base unit for performing prediction, quantization, transform or in-loop filtering and the like.
[00102] Partitioning of a coding tree unit or a coding unit may be performed based on at least one of a vertical line and a horizontal line. In addition, the number of vertical lines or horizontal lines partitioning the coding tree unit or the coding unit may be at least one or more. For example, the coding tree unit or the coding unit may be divided into two partitions using one vertical line or one horizontal line, or the coding tree unit or the coding unit may be divided into three partitions using two vertical lines or two horizontal lines. Alternatively, the coding tree unit or the coding unit may be partitioned into four partitions having a length and a width of 1/2 by using one vertical line and one horizontal line.
[00103] When a coding tree unit or a coding unit is divided into a plurality of partitions using at least one vertical line or at least one horizontal line, the partitions may have a uniform size or a different size. Alternatively, any one partition may have a

different size from the remaining partitions. [00104] In the embodiments described below, it is assumed that a coding tree unit or a coding unit is divided into a quad tree structure or a binary tree structure. However, it is also possible to divide a coding tree unit or a coding unit using a larger number of vertical lines or a larger number of horizontal lines.
[00105] FIG. 3 is a diagram illustrating an example of hierarchically partitioning a coding block based on a tree structure according to an embodiment of the present invention.
[00106] An input video signal is decoded in predetermined block units. Such a default unit for decoding the input video signal is a coding block. The coding block may be a unit performing intra/inter prediction, transform, and quantization. In addition, a prediction mode (e.g., intra prediction mode or inter prediction mode) is determined in a unit of a coding block, and the prediction blocks included in the coding block may share the determined prediction mode. The coding block may be a square or non-square block having an arbitrary size in a range of 8x8 to 64x64, or may be a square or non-square block having a size of 128x128, 256x256, or more.
[00107] Specifically, the coding block may be hierarchically partitioned based on at least one of a quad tree and a binary tree. Here, quad tree-based partitioning may mean that a 2Nx2N coding block is partitioned into four NxN coding blocks, and binary tree-based partitioning may mean that one coding block is partitioned into two coding blocks. Even if the binary tree-based partitioning is performed, a square-shaped coding block may exist in the lower depth. [00108] Binary tree-based partitioning may be symmetrically or asymmetrically performed. The coding

block partitioned based on the binary tree may be a square block or a non-square block, such as a rectangular shape. For example, a partition type in which the binary tree-based partitioning is allowed may comprise at least one of a symmetric type of 2NxN (horizontal directional non-square coding unit) or Nx2N (vertical direction non-square coding unit), asymmetric type of nLx2N, nRx2N, 2NxnU, or 2NxnD. [00109] Binary tree-based partitioning may be limitedly allowed to one of a symmetric or an asymmetric type partition. In this case, constructing the coding tree unit with square blocks may correspond to quad tree CU partitioning, and constructing the coding tree unit with symmetric non-square blocks may correspond to binary tree partitioning. Constructing the coding tree unit with square blocks and symmetric non-square blocks may correspond to quad and binary tree CU partitioning.
[00110] Binary tree-based partitioning may be performed on a coding block where quad tree-based partitioning is no longer performed. Quad tree-based partitioning may no longer be performed on the coding block partitioned based on the binary tree. [00111] Furthermore, partitioning of a lower depth may be determined depending on a partition type of an upper depth. For example, if binary tree-based partitioning is allowed in two or more depths, only the same type as the binary tree partitioning of the upper depth may be allowed in the lower depth. For example, if the binary tree-based partitioning in the upper depth is performed with 2NxN type, the binary tree-based partitioning in the lower depth is also performed with 2NxN type. Alternatively, if the binary tree-based partitioning in the upper depth is performed with Nx2N type, the binary tree-based partitioning in the lower depth is also performed with

Nx2N type.
[00112] On the contrary, it is also possible to allow, in a lower depth, only a type different from a binary tree partitioning type of an upper depth. [00113] It may be possible to limit only a specific type of binary tree based partitioning to be used for sequence, slice, coding tree unit, or coding unit. As an example, only 2NxN type or Nx2N type of binary tree-based partitioning may be allowed for the coding tree unit. An available partition type may be predefined in an encoder or a decoder. Or information on available partition type or on unavailable partition type on may be encoded and then signaled through a bitstream.
[00114] FIG. 5 is a diagram illustrating an example in which only a specific type of binary tree-based partitioning is allowed. FIG. 5A shows an example in which only Nx2N type of binary tree-based partitioning is allowed, and FIG. 5B shows an example in which only 2NxN type of binary tree-based partitioning is allowed. In order to implement adaptive partitioning based on the quad tree or binary tree, information indicating quad tree-based partitioning, information on the size/depth of the coding block that quad tree-based partitioning is allowed, information indicating binary tree-based partitioning, information on the size/depth of the coding block that binary tree-based partitioning is allowed, information on the size/depth of the coding block that binary tree-based partitioning is not allowed, information on whether binary tree-based partitioning is performed in a vertical direction or a horizontal direction, etc. may be used.
[00115] In addition, information on the number of times a binary tree partitioning is allowed, a depth at which the binary tree partitioning is allowed, or

the number of the depths at which the binary tree partitioning is allowed may be obtained for a coding tree unit or a specific coding unit. The information may be encoded in a unit of a coding tree unit or a coding unit, and may be transmitted to a decoder through a bitstream.
[00116] For example, a syntax
'max_binary_depth_idx_minusl' indicating a maximum depth at which binary tree partitioning is allowed may be encoded / decoded through a bitstream. In this case, max_binary_depth_idx_minusl + 1 may indicate the maximum depth at which the binary tree partitioning is allowed.
[00117] Referring to the example shown in FIG. 6, in FIG. 6, the binary tree partitioning has been performed for a coding unit having a depth of 2 and a coding unit having a depth of 3. Accordingly, at least one of information indicating the number of times the binary tree partitioning in the coding tree unit has been performed (i.e., 2 times), information indicating the maximum depth which the binary tree partitioning has been allowed in the coding tree unit (i.e., depth 3) , or the number of depths in which the binary tree partitioning has been performed in the coding tree unit (i.e., 2 (depth 2 and depth 3)) may be encoded / decoded through a bitstream.
[00118] As another example, at least one of information on the number of times the binary tree partitioning is permitted, the depth at which the binary tree partitioning is allowed, or the number of the depths at which the binary tree partitioning is allowed may be obtained for each sequence or each slice. For example, the information may be encoded in a unit of a sequence, a picture, or a slice unit and transmitted through a bitstream. Accordingly, at least one of the number of the binary tree partitioning in a

first slice, the maximum depth in which the binary tree partitioning is allowed in the first slice, or the number of depths in which the binary tree partitioning is performed in the first slice may be difference from a second slice. For example, in the first slice, binary tree partitioning may be permitted for only one depth, while in the second slice, binary tree partitioning may be permitted for two depths. [00119] As another example, the number of times the binary tree partitioning is permitted, the depth at which the binary tree partitioning is allowed, or the number of depths at which the binary tree partitioning is allowed may be set differently according to a time level identifier (TemporallD) of a slice or a picture. Here, the temporal level identifier (TemporallD) is used to identify each of a plurality of layers of video having a scalability of at least one of view, spatial, temporal or quality.
[00120] As shown in FIG. 3, the first coding block 300 with the partition depth (split depth) of k may be partitioned into multiple second coding blocks based on the quad tree. For example, the second coding blocks 310 to 340 may be square blocks having the half width and the half height of the first coding block, and the partition depth of the second coding block may be increased to k+1.
[00121] The second coding block 310 with the partition depth of k+1 may be partitioned into multiple third coding blocks with the partition depth of k+2. Partitioning of the second coding block 310 may be performed by selectively using one of the quad tree and the binary tree depending on a partitioning method. Here, the partitioning method may be determined based on at least one of the information indicating quad tree-based partitioning and the information indicating binary tree-based partitioning.

[00122] When the second coding block 310 is partitioned based on the quad tree, the second coding block 310 may be partitioned into four third coding blocks 310a having the half width and the half height of the second coding block, and the partition depth of the third coding block 310a may be increased to k+2. In contrast, when the second coding block 310 is partitioned based on the binary tree, the second coding block 310 may be partitioned into two third coding blocks. Here, each of two third coding blocks may be a non-square block having one of the half width and the half height of the second coding block, and the partition depth may be increased to k+2. The second coding block may be determined as a non-square block of a horizontal direction or a vertical direction depending on a partitioning direction, and the partitioning direction may be determined based on the information on whether binary tree-based partitioning is performed in a vertical direction or a horizontal direction.
[00123] In the meantime, the second coding block 310 may be determined as a leaf coding block that is no longer partitioned based on the quad tree or the binary tree. In this case, the leaf coding block may be used as a prediction block or a transform block. [00124] Like partitioning of the second coding block 310, the third coding block 310a may be determined as a leaf coding block, or may be further partitioned based on the quad tree or the binary tree. [00125] In the meantime, the third coding block 310b partitioned based on the binary tree may be further partitioned into coding blocks 310b-2 of a vertical direction or coding blocks 310b-3 of a horizontal direction based on the binary tree, and the partition depth of the relevant coding blocks may be increased to k+3. Alternatively, the third coding