Patent Publication Number: US-11659209-B2

Title: Video coding method and apparatus utilizing group of encoding units

Description:
RELATED APPLICATIONS 
     This is a continuation of U.S. application Ser. No. 16/378,499, filed Apr. 8, 2019, which is a continuation application of the International Patent Application Serial No. PCT/KR2016/011524, filed Oct. 14, 2016, which claims priority to the Korean Patent Application Serial No. 10-2016-0132602, filed Oct. 13, 2016. Both of these applications are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an image processing scheme and, more particularly, to a method and apparatus for describing a block partitioning structure and a syntax on the block partitioning structure in a bitstream in a video compression scheme. 
     BACKGROUND 
     The demand for multimedia data is increasing due to diversification and miniaturization of multimedia devices, and thus there has been a need for a high efficiency video compression technology for next generation video services. Based on such a need, the MPEG and VCEG jointly established the Joint Collaborative Team on Video Coding (JCT-VC) of the video compression standardization of H.264/AVC, and established in January 2013 the standardization for HEVC, which is the latest international video compression standard. In addition, the MPEG and VCEG jointly standardized various HEVC extensions, and established the Joint Video Exploration Team (JVET) in 2015 to research the next generation video compression standards after HEVC. 
     In the video compression technology, a block partitioning structure refers to a unit in which encoding and decoding are performed, and a unit to which main encoding and decoding technologies such as prediction and transform are applied. As the video compression technology develops, the magnitude of blocks for performing encoding and decoding is gradually increasing, and in terms of block partitioning forms, more various partitioning forms are supported. In addition, the video compression is performed using units subdivided according to roles of blocks as well as units for performing encoding and decoding. In the HEVC standard, video coding and decoding are performed using unit blocks subdivided according to a block partitioning structure of quad-tree type and roles of prediction and transform. In addition, various forms of block partitioning structures such as a Quad-Tree plus Binary-Tree (QTBT) which is a form of a combination of a quad-tree and a binary-tree, a block partitioning structure of any form, and the like have been proposed for improving video encoding efficiency. In block structures having various block depths from block sizes of 128×128, 256×256, and the like to a block size of 8×8, the number of bits used for expressing block structures of various sizes and types or for representing a lot of block data is greatly increasing. 
     SUMMARY 
     It is an object of the present invention to provide a method and an apparatus capable of improving encoding efficiency compared to the existing video compression schemes by which one or more encoding blocks are combined into a group and then encoded. 
     However, the technical problem to be solved by this embodiment is not limited to the above-described technical problems, and other technical problems may exist. 
     In order to achieve the objects, video encoding and decoding method and apparatus according to an embodiment of the present invention includes a combiner for combining two or more encoding units of maximum size into a single encoding unit group; an acquirer for acquiring encoding information corresponding to the single encoding unit group; and an decoder for performing decoding on the two or more encoding units of maximum size included in the single encoding unit group according to a decoding order. 
     In order to achieve the objects, according to an embodiment of the present invention, the combiner for combining the two or more encoding units of maximum size into a single encoding unit group includes: a determiner for determining whether the encoding unit group is used or not; a determiner for determining the number of encoding units of maximum size to be included in the encoding unit group; and a determiner for determining the decoding order of the encoding units of maximum size to be included in the encoding unit group. 
     In order to achieve the objects, according to an embodiment of the present invention, the acquirer for acquiring the encoding information corresponding to the single encoding unit group includes: an acquirer for acquiring a syntax to be applied to the encoding unit group; an acquirer for acquiring encoding information commonly applied to the two or more encoding units of maximum size included in the encoding unit group using the acquired syntax information; and a storage for storing the encoding information commonly applied to the two or more encoding units of maximum size included in the encoding unit group. 
     In order to achieve the objects, according to an embodiment of the present invention, the decoder for performing decoding on the two or more encoding units of maximum size included in the single encoding unit group according to the decoding order includes: an acquirer for acquiring the decoding order for the two or more encoding units of maximum size included in the single encoding unit group; and a decoder for performing decoding on the encoding units of maximum size according to the acquired decoding order. 
     It is an object of the present invention to provide a video coding method and apparatus for efficiently representing and encoding information of partitioned encoding blocks in video coding method and apparatus using a block structure of various sizes and shapes to improve the encoding efficiency. 
     According to an embodiment of the present invention, information of one or more encoding blocks is combined into one or more groups and then encoded, thereby improving the encoding performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram illustrating a configuration of a video encoding apparatus according to an embodiment of the present invention. 
         FIG.  2    is a block diagram illustrating a configuration of a video decoding apparatus according to an embodiment of the present invention. 
         FIG.  3    is a conceptual diagram illustrating diverse types of block partitioning and a block in which diverse block partitioning is combined according to an embodiment of the present invention. 
         FIG.  4    is a conceptual diagram illustrating a single encoding unit group in which a plurality of encoding units are combined into a single group according to an embodiment of the present invention. 
         FIG.  5    is a view illustrating an example of syntax for each encoding unit group in which a plurality of encoding units are combined into a single group according to an embodiment of the present invention. 
         FIG.  6    is a view illustrating an example of a decoding order of each encoding unit in a encoding unit group according to an embodiment of the present invention. 
         FIG.  7    is a view illustrating an example of a decoding order of each encoding unit in a encoding unit group according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings attached thereto, so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification. 
     Throughout this specification, when a part is referred to as being ‘connected’ to another part, it includes not only an example where they are directly connected but also an example where the part is electrically connected with another part in between. 
     In addition, when a part is referred to as ‘comprising’ an element throughout the specification, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. 
     The term ‘a step of doing something’ or ‘a step of something’ used throughout this specification does not mean a step for something. 
     Also, the terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. 
     In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, but that does not mean that each component consists of separate hardware or one software constituent unit. That is, each component is described by arranging each component for convenience of explanation, and at least two components of components may be combined to form one component or one component may be partitioned into a plurality of components to perform functions. The integrated embodiments and the separate embodiments of each of these components are also included in the scope of the present invention without departing from the essence of the present invention. 
     In the various embodiments of the present invention described herein below, the color format refers to a form of color components constituting one picture, and the encoding block or encoding unit may be collectively referred to as including a single block or unit in which encoding and decoding are performed in video coding. The color format is not limited to a YUV format, and may be collectively referred to as including all kinds of a plurality of color formats according to color components for constituting one picture. 
     Hereinafter, a video coding method and apparatus utilizing a combination of diverse block partitioning structures proposed according to an embodiment of the present invention will be described in detail with reference to  FIG.  4   . 
       FIG.  4    is a conceptual diagram illustrating a single encoding unit group in which a plurality of encoding units are combined into a single group according to an embodiment of the present invention. 
     The video coding method and apparatus according to an embodiment of the present invention may use a encoding unit group  400  obtained by combining two or more encoding units  410 ,  420 ,  430 , and  440  of maximum size into one group to combine a plurality of encoding units into one group. The encoding unit group  400  according to an embodiment of the present invention illustrated in  FIG.  5    includes a first encoding unit  410  of maximum size, a second encoding unit  420  of maximum size, a third encoding unit  430  of maximum size, and a forth encoding unit  440  of maximum size. 
     A encoding unit group  440  according to an embodiment of the present invention shares encoding information commonly applied to encoding units of maximum size included in a corresponding group. The encoding information commonly applied to the encoding units of maximum size included in the group may include Sample Adaptive Offset (SAO) information, Adaptive Loop Filter (ALF) information, Quantization Parameter (QP), and the like. Also, a decoding order of the encoding units of maximum size included in the encoding unit group  440  may be designated. In addition, the location of the encoding unit of maximum size to be initially decoded in the group may be selected with respect to the decoding order of the encoding units of maximum size included in the encoding unit group  440 . 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings attached thereto, so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification. 
     Throughout this specification, when a part is referred to as being ‘connected’ to another part, it includes not only an example where they are directly connected but also an example where the part is electrically connected with another part in between. 
     In addition, when a part is referred to as ‘comprising’ an element throughout the specification, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. 
     The term ‘a step of doing something’ or ‘a step of something’ used throughout this specification does not mean a step for something. 
     Also, the terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. 
     In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, and that does not mean that each component consists of separate hardware or one software constituent unit. That is, each component is described by arranging each component for convenience of explanation, and at least two components of components may be combined to form one component or one component may be partitioned into a plurality of components to perform functions. The integrated embodiments and the separate embodiments of each of these components are also included in the scope of the present invention without departing from the essence of the present invention. 
     In the various embodiments of the present invention described herein below, the color format refers to a form of color components constituting one picture, and the encoding block or encoding unit may be collectively referred to as including a single block or unit in which encoding and decoding are performed in video coding. The color format is not limited to a YUV format, and may be collectively referred to as including all kinds of a plurality of color formats according to color components for constituting one picture. 
     Hereinafter, a video coding method and apparatus utilizing a combination of diverse block partitioning structures proposed according to an embodiment of the present invention will be described in detail with reference to  FIG.  4   . 
       FIG.  1    is a block diagram illustrating a configuration of video encoding method and apparatus according to an embodiment of the present invention. 
     Video encoding method and apparatus according to an embodiment of the present invention may include an inter prediction unit  120 , an intra prediction unit  125 , a subtraction unit  130 , a transform unit  140 , a quantization unit  150 , an entropy encoding unit  160 , inverse transform unit  145 , an inverse quantization unit  155 , an adding unit  135 , an in-loop filter unit  180 , and a reconstructed picture buffer  190 . 
     The inter prediction unit  120  performs motion prediction by using an input image  110  and a reconstructed image stored in the reconstructed picture buffer  190 , thereby generating a prediction signal. 
     The intra-picture prediction unit  125  performs spatial prediction by using a pixel value of a pre-reconstructed neighboring block that are adjacent to the current block to be encoded, thereby generating a prediction signal. 
     The subtraction unit  130  uses the input image and the prediction signal generated through the inter prediction unit  120  or the intra-picture prediction unit  125  to generate a residual signal. 
     The transform unit  140  and the quantization unit  150  perform transform and quantization on the residual signal generated through the subtraction unit  130  to generate a quantized coefficient. 
     The entropy encoding unit  160  performs entropy encoding on encoding information such as syntax elements and quantized coefficients defined in the video encoder, thereby outputting the bitstream. 
     The inverse transform unit  145  and the inverse quantization unit  155  receive the quantized coefficients; and perform inverse quantization and inverse transform in order, thereby generating a reconstructed residual signal. 
     The adding unit  135  generates a reconstructed signal by using the prediction signal generated through the inter prediction unit  120  or the intra prediction unit  125  and the reconstructed residual signal. 
     The reconstructed signal is transmitted to the in-loop filter unit  180 . The reconstructed picture to which the filtering is applied is stored in the reconstructed picture buffer  190 , and may be used as a reference picture in the inter prediction unit  120 . 
       FIG.  2    is a block diagram showing a configuration of video decoding apparatus and method according to an embodiment of the present invention. 
     The video decoding apparatus and method according to one embodiment includes an entropy decoding unit  210 , an inverse quantization unit  220 , an inverse transform unit  230 , an intra prediction unit  240 , an inter prediction unit  250 , an adding unit  260 , an in-loop filter unit  270 , and a reconstructed picture buffer  280 . 
     The entropy decoding unit  210  decodes the input bitstream  200  and outputs decoding information such as syntax elements and quantized coefficients. 
     The inverse quantization unit  220  and the inverse transform unit  230  receive the quantized coefficients and perform inverse quantization and inverse transform in order, thereby outputting a residual signal. 
     The intra prediction unit  240  performs spatial prediction by using a pixel value of the pre-reconstructed neighboring block adjacent to the current block to be decoded, thereby generating a prediction signal. 
     The inter prediction unit  250  performs motion compensation using motion vector extracted from the bitstream and a reconstructed picture stored in the reconstructed picture buffer  280 , thereby generating a prediction signal. 
     The prediction signal output from the intra prediction unit  240  and the inter prediction unit  250  are summed with the residual signal through the adding unit  260 , and accordingly the reconstructed signal generated on a per-block basis includes the reconstructed image. 
     The reconstructed image is transferred to the in-loop filter unit  270 . The reconstructed picture to which the filtering is applied is stored in the reconstructed picture buffer  280  and may be used as a reference picture in the inter prediction unit  250 . 
       FIG.  3    is a conceptual diagram illustrating diverse types of block partitioning and a block in which diverse block partitioning is combined according to an embodiment of the present invention. 
     A video coding method and apparatus utilizing a combination of diverse block partitioning structures according to an embodiment of the present invention includes block partitioning forms including a non-partitioned block  310 , a horizontally partitioned block  320 , a vertically partitioned block  330 , quad-partitioned block  340 , and a block structure  350  having a form of a combination of diverse block partitioning structures. 
     According to an embodiment of the present invention, the non-partitioned block  310  includes a form in which one encoding block is not partitioned, and the horizontally partitioned block  320  includes a form in which one encoding block is horizontally partitioned. In addition, according to an embodiment of the present invention, the vertically partitioned block  330  includes a form in which one encoding block is vertically partitioned, and the quad-partitioned block  340  includes a form in which one encoding block is vertically and horizontally partitioned. The one encoding block includes both a square block and a non-square block. 
     The block structure  350  having a form of a combination of diverse block partitioning structures according to an embodiment of the present invention includes a block structure of a form in which blocks  310 ,  320 ,  330 , and  340  of diverse block partitioning forms are combined. In the block partitioning structure according to the embodiment, the upper block  350  may be partitioned into four sub-blocks, i.e., a first sub-block  351 , a second sub-block  352 , a third sub-block  353 , and a fourth sub-block  354 . The first sub-block  351  according to an embodiment of the present invention is a block represented by the block partitioning form of the block  310  of a non-partitioned form, and the second sub-block  352  is a block represented by block partitioning of the block  340  of a quad-partitioned form. The one encoding block may be partitioned into one or more sub-blocks, and the partitioned sub-blocks may be repeatedly partitioned. The second sub-block  352  is quad-partitioned into four sub-sub-blocks, and each sub-sub-block indicates a block represented by block partitioning of the non-partitioned block  310 . The third sub-block  353  is a block represented by the block partitioning of the horizontally partitioned block  320  and the lower end rectangular block  356  of the sub-sub-blocks is a block represented by block partitioning of the vertically partitioned block  330 . The fourth sub-block  354  is a block represented by block partitioning of the quad-partitioned block  340 , and the first sub-sub-block and the third sub-sub-block of the fourth sub-block are blocks represented by block partitioning of the vertically partitioned block  330 . Herein, the third sub-sub-block represents an embodiment in which additional vertical partitioning is performed. 
       FIG.  5    is a view illustrating an example of syntax for each encoding unit group in which a plurality of encoding units are combined into a single group according to an embodiment of the present invention. 
     The video coding method and apparatus according to an embodiment of the present invention is provided such that, in order to combine a plurality of encoding unit into a single group and then perform decoding, encoding information which are applied in common to the encoding units of maximum size included in the group, a decoding order of the encoding units of maximum size, and location information of the encoding unit of maximum size to be initially decoded, and the like are included. 
     The encoding information, which is commonly applied to the encoding units of maximum size included in the group according to an embodiment of the present invention, is obtained by parsing syntax information for each group once on a per-group basis and acquiring the information and is applied in common to all the encoding units of maximum size included in the group. SAO information  510  may be included as an example of syntax for each encoding unit group in which a plurality of encoding units are combined into one group according to an embodiment of the present invention as shown in  FIG.  5   . The SAO information  510  is commonly applied to all the encoding units of maximum size included in the group, thereby improving encoding efficiency, compared to using SAO information on a per-existing maximum-size encoding unit basis. 
     The encoding information commonly applied to the encoding units of maximum size included in the group according to an embodiment of the present invention includes a decoding order  530  of the encoding unit of maximum size. Whether a decoding order of the encoding unit of maximum size is used or not  520  is acquired through high-level syntax information, and the high-level syntax information includes a sequence parameter, a picture parameter, and the like. In the case that whether the decoding order of the encoding unit of maximum size is used or not  520  is true, the decoding order of the encoding unit of maximum size is acquired and applied to the decoding  560  of the encoding units of maximum size. 
     The encoding information commonly applied to the encoding units of the maximum size included in the group according to an embodiment of the present invention includes an initial decoding position  550  of the encoding unit of maximum size. Whether an initial decoding position of the encoding unit of maximum size is used or not  540  is acquired through the high-level syntax information, and the high-level syntax information includes a sequence parameter, a picture parameter, and the like. In the case that whether the initial decoding position of the encoding unit of maximum size is used or not  540  is true, the initial decoding position of the encoding unit of maximum size is acquired and applied to the decoding  560  of the decoding unit of maximum size. 
       FIG.  6    is a view illustrating an example of a decoding order of each encoding unit in a encoding unit group according to an embodiment of the present invention. 
     The video coding method and apparatus according to an embodiment of the present invention includes selectively changing the decoding order of each encoding unit in the encoding unit group. The decoding order of each encoding unit in the encoding unit group is performed according to the decoding order  530  of the encoding units of maximum size. 
     The decoding order  530  of the encoding unit of maximum size according to an embodiment of the present invention includes a decoding order  610  in which the decoding is performed in this order of a first encoding unit  611  of maximum size, a second encoding unit  612  of maximum size, a third encoding unit  613  of maximum size, a fourth encoding unit  614  of maximum size. 
     The decoding order  530  of the encoding unit of maximum size according to an embodiment of the present invention includes a decoding order  620  in which the decoding is performed in this order of a first encoding unit  621  of maximum size, a third encoding unit  622  of maximum size, a second encoding unit  622  of maximum size, a fourth encoding unit  624  of maximum size. 
     The decoding order  530  of the encoding unit of maximum size according to an embodiment of the present invention includes a decoding order  630  in which the decoding is performed in this order of a first encoding unit  631  of maximum size, a second encoding unit  632  of maximum size, a fourth encoding unit  634  of maximum size, a third encoding unit  633  of maximum size. 
     The decoding order  530  of the encoding unit of maximum size according to an embodiment of the present invention includes a decoding order  640  in which the decoding is performed in this order of a first encoding unit  641  of maximum size, a third encoding unit  643  of maximum size, a fourth encoding unit  644  of maximum size, a second encoding unit  642  of maximum size. 
       FIG.  7    is a view illustrating an example of a decoding order of each encoding unit in a encoding unit group according to an embodiment of the present invention. 
     The video coding method and apparatus according to an embodiment of the present invention includes selectively changing the initial decoding position in the encoding unit group. The changing of the initial decoding position in the single encoding unit group is performed according to the initial decoding position  550  of the encoding unit of maximum size. 
     The initial decoding position  550  of the encoding units of maximum size according to an embodiment of the present invention is selected as one of all the encoding units of maximum size in a group including a first encoding unit of maximum size  711 , a second encoding unit of maximum size  712 , a third encoding unit of maximum size  713 , and a fourth encoding unit of maximum size  714 . In  FIG.  7   , as the initial decoding position  550  of the encoding unit of maximum size according to an embodiment of the present invention, there are shown an example  710  in which the second encoding unit  712  of maximum size is selected and an example  720  in which the third encoding unit  723  of maximum size is selected. The first encoding units  711  of maximum size and the fourth encoding units  714  of maximum size may be selected as the initial decoding positions  550  of the encoding unit of maximum size, including the example. 
     The present invention can be used for broadcasting equipment manufacturing, terminal manufacturing, and the like, and for industries related to source technology.