BR122021004831B1 - Method to decode an encoded video - Google Patents

Abstract

Encoding and decoding of a video using a transformation index that indicates information that indicates a structure of a transformation unit transforming the data of a current encoding unit.

Description

Technical Field

[0001] Exemplary modalities refer to video encoding, and video decoding, in which the transformation between a spatial domain and a transformation domain is performed.

Fundamentals of Technique

[0002] As hardware for playing and storing high-resolution, high-quality video content is being developed and provided, the need for a video codec to effectively encode or decode high-resolution or high-quality video content grows. quality. In a conventional video codec, a video is encoded according to a limited encoding method based on a macroblock that has a predetermined size. In the conventional video codec, video data is encoded and decoded by performing transformation and inverse transformation into macroblocks using blocks, each of which is the same size.

Revelation of the Invention Technical problem

[0003] Exemplary modalities refer to video encoding and video decoding in which the transformation between a spatial domain and a transformation domain is performed.

Solution to the Problem

[0004] According to one aspect of an exemplary embodiment, there is provided a method of encoding a video including: determining a transform unit which is a data unit into which an actual encoding unit is transformed, the encoding unit being a data unit in which a current video image is encoded; transforming the current encoding unit data based on the determined transformation unit to encode the current encoding unit data; and outputting the encoded data of the current encoding unit, encoding mode information indicating a mode of encoding the encoded data of the current encoding unit, and transformation index information indicating a structure of the transforming unit transforming the data of the unit current encoding, as a bit stream.

Advantageous Effects of the Invention

[0005] A video encoding apparatus according to an exemplary embodiment, and a video decoding apparatus, according to an exemplary embodiment, can efficiently encode and decode the information used to determine the various sizes and formats of the transformer units. having a tree structure, which are necessary to perform the transformation and inverse transformation during video encoding and decoding based on the various sizes and formats of the encoding units, by using the transform index according to an exemplary embodiment.

Brief Description of Drawings

[0006] Figure 1 is a block diagram of video encoding equipment using a transform index, according to an exemplary embodiment;

[0007] Figure 2 is a block diagram of a video decoding equipment using a transform index, according to an exemplary embodiment;

[0008] Figure 3 is a diagram illustrating the structure of a transformation unit and a transformation index, according to an exemplary embodiment;

[0009] Figure 4 is a diagram illustrating the structure of a transformation unit and a transformation index, according to an exemplary embodiment;

[00010] Figures 5 and 6 are diagrams illustrating examples of use of the transformation index, according to an exemplary embodiment;

[00011] Figure 7 is a flowchart illustrating a video encoding method using a transform index, according to an exemplary embodiment;

[00012] Figure 8 is a flowchart illustrating a video decoding method using a transform index, according to an exemplary embodiment;

[00013] Figure 9 is a block diagram of an encoding and video equipment using encoding units having a tree structure and a transform index, according to an exemplary embodiment;

[00014] Figure 10 is a block diagram of a video decoding apparatus using encoding units having a tree structure and a transform index, according to an exemplary embodiment;

[00015] Figure 11 is a diagram for describing a concept of encoding units according to an exemplary embodiment;

[00016] Figure 12 is a block diagram of an image encoder based on encoding units according to an exemplary embodiment;

[00017] Figure 13 is a block diagram of an image decoder based on encoding units according to an exemplary embodiment;

[00018] Figure 14 is a diagram illustrating deeper encoding units according to depths, and partitions according to an exemplary embodiment;

[00019] Figure 15 is a diagram for describing a relationship between an encoding unit and transformation units, according to an exemplary embodiment;

[00020] Figure 16 is a diagram for describing encoding information of encoding units corresponding to an encoded depth, according to an exemplary embodiment;

[00021] Figure 17 is a diagram of deeper coding units according to depths, according to an exemplary embodiment;

[00022] Figures 18 to 20 are diagrams for describing a relationship between encoding units, prediction units, and transformation units, according to an exemplary embodiment;

[00023] Figure 21 is a diagram for describing a relationship between an encoding unit, a prediction unit or partition, and a transformation unit, in accordance with encoding mode information from Table 1;

[00024] Fig. 22 is a flowchart illustrating a video encoding method using a transform index based on encoding units and transforming units having a tree structure, according to an exemplary embodiment; and

[00025] Fig. 23 is a flowchart illustrating a video decoding method using a transform index based on encoding units and transforming units having a tree structure, according to an exemplary embodiment.

Best Mode for Carrying Out the Invention

[00026] According to one aspect of an exemplary embodiment, there is provided a method of encoding a video including: determining a transform unit which is a data unit into which an actual encoding unit is transformed, the encoding unit being a data unit in which a current video image is encoded; transforming the current encoding unit data based on the determined transformation unit to encode the current encoding unit data; and outputting the encoded data of the current encoding unit, encoding mode information indicating a mode of encoding the encoded data of the current encoding unit, and transformation index information indicating a structure of the transforming unit transforming the data of the unit current encoding, as a bit stream.

[00027] According to another aspect of an exemplary embodiment, there is provided a method of decoding an encoded video including: receiving a bit stream of the encoded video and analyzing the received bit stream; extracting the encoded data from a current encoding unit which is a data unit in which a current image of the encoded video is encoded, encoding mode information which indicates an encoding mode of the encoded data of the current encoding unit, and transformation index that indicates a structure of a transformation unit which is a data unit into which the data of the current encoding unit is transformed, from the parsed bit stream; and performing inverse transformation on the encoded data of the current encoding unit based on the transformation index information to decode the encoded data of the current encoding unit transformed in the transformation unit.

[00028] According to another aspect of an exemplary embodiment, video encoding equipment including a processor is provided, the equipment including: a transform unit determiner which determines a transform unit which is a data unit in which a current encoding unit is transformed, the encoding unit being a data unit in which a current image of a received video is encoded; an encoding unit that transforms the data of the current encoding unit based on the transformation unit determined to encode the data of the current encoding unit; and an encoded data output unit that outputs the encoded data from the current encoding unit, encoding mode information indicating a mode of encoding the encoded data from the current encoding unit, and transformation index information indicating a structure of the encoding unit. transformation unit transforming the data from the current encoding unit.

[00029] According to another aspect of an exemplary embodiment, video decoding equipment including a processor is provided, the equipment including: a receiver that receives a bit stream of an encoded video and analyzes the received bit stream; an extractor which extracts encoded data from a current encoding unit which is a data unit in which a current image of the encoded video is encoded, encoding mode information indicating an encoding mode of the encoded data of the current encoding unit, and transform index information indicating a structure of a transform unit which is a data unit into which the current encoding unit is transformed from the parsed bit stream; and a decoder that performs inverse transformation on the encoded data of the current encoding unit based on the transform index information to decode the encoded data of the current encoding unit transformed in the transformation unit.

[00030] According to another aspect of an exemplary embodiment, there is provided video encoding equipment including a processor, the equipment including: a maximum encoding unit splitter which divides a current image into at least one maximum encoding unit; a coding unit determiner which determines coding units having a tree structure that includes coding units of a coded depth that are hierarchical according to depths in the same region as at least one maximum coding unit and independent in regions by independently determining a coding unit of a coded depth to output a coding result for each deepest coding unit out of all the deepest coding units constructed hierarchically according to the depths indicating the numbers of times wherein the at least one maximum encoding unit is spatially divided, for each of the at least one maximum encoding unit, and determining a transform unit being a data unit in which a current encoding unit among the encoding units having the tree structure is transf ormed, to encode the current encoding unit by including transformation based on the transformation unit; and an output unit that encodes and outputs the encoded data of the current image, information about an encoded depth of encoding units having the tree structure and an encoding mode, and transformation index information about a structure of the transformation units of the coding units of the coded depth, for each of the maximum coding units.

[00031] According to another aspect of an exemplary embodiment, video decoding equipment including a processor is provided, the equipment including: a receiver that receives a bit stream of an encoded video and analyzes the received bit stream; an encoded information and image data extractor that extracts encoded data from an image, information about an encoded depth and an encoding mode, and transformation index information about a transformation unit structure of encoding units of the encoded depth , according to the encoding units having a tree structure included in each of the several maximum encoding units into which the image is divided from the analyzed bit stream; and a picture data decoder that decodes the encoded data by performing inverse transformation on the encoded depth encoding units, based on the transformation units obtained based on the transformation index information, for each of the plurality of maximum encoding units , wherein the coding units having the tree structure comprise coding units corresponding to a determined coding depth to produce an coding result from the deeper coding units constructed hierarchically according to the depths indicating the number of times in that the maximum encoding unit is spatially divided when at least one of several maximum encoding units is encoded.

[00032] According to another aspect of an exemplary embodiment, a computer readable recording medium is provided which has recorded therein a program for performing the method of encoding a video.

[00033] According to another aspect of an exemplary embodiment, a computer readable recording medium is provided which has recorded therein a program for performing the method of decoding a video.

Mode for Invention

[00034] In the following, exemplary embodiments will be described more fully with reference to the accompanying drawings, in which exemplary embodiments are shown. In exemplary embodiments, "unit" may or may not refer to a unit of size, depending on its context; and an "image" may denote a still image for a video or a moving image, that is, the video itself.

[00035] Next, an "encoding unit" is an encoding data unit in which the image data is encoded on one encoder side and an encoded data unit in which the encoded image data is decoded on one side decoder, according to the exemplary modalities. Also, an "encoded depth" indicates a depth where an encoding unit is encoded.

[00036] The encoding and decoding of a video using a transformation index based on transformation units having a tree structure, according to an exemplary embodiment, will be described with reference to Figures 1 to 8. The encoding and decoding a video using a transform index based on encoding units and transforming units having a tree structure, according to an exemplary embodiment, will be described with reference to Figures 9 to 23.

[00037] First, a method and equipment for encoding video using a transform index and a method and equipment for decoding video using a transform index, according to an exemplary embodiment, will be described with reference to the Figures 1 to 8.

[00038] Figure 1 is a block diagram of a video encoding apparatus 10 using a transform index, according to an exemplary embodiment.

[00039] Referring to Figure 1, video encoding equipment 10 using a transform index includes a transform unit determiner 12, an encoding unit 14, and an encoded data output unit 16. For convenience of explanation , the video encoding equipment using a transform index will be referred to as a video encoding equipment 10. The operations of the transform unit determiner 12, the encoding unit 14, and the encoded data output unit 16 of the equipment encoding modules 10 may be organically controlled by a video encoding processor (not shown), by a central processing unit (CPU), by a graphics processing unit (GPU), or the like.

[00040] The video encoding apparatus 10 divides a current image of a received video into a data unit, each unit having a predetermined size, and performs encoding on each of the data units to encode the current image. Then, a unit of data in which the current image is encoded is referred to as an "encoding unit". Video encoding equipment 10 can encode the current image by performing predictive encoding including inter prediction and intra prediction, transformation and quantization, entropy coding in each coding unit.

[00041] The transform unit determiner 12 determines a transform unit, that is, a data unit into which a current encoding unit, among the encoding units of the current image, is transformed. The transform unit may be included in the current encoding unit, and may be determined to be a data unit that has a size less than or equal to the current encoding unit. The transform unit determiner 12 can generate the transform unit by dividing the height and width of the current encoding unit into two parts, that is, dividing the current encoding unit into four equal parts.

[00042] The transform unit determiner 12 can generate transform units of a lower level by dividing the height and width of the transform unit into two parts. The transform unit determiner 12 can divide the current encoding unit into transform units each having the same size by dividing all transform units into transform units of a lower level. As the height and width of each transform unit are divided into two equal parts, the current encoding unit can be divided into transform units each having the same size, and the total number of transform units of a lower level is four to the power of a positive integer.

[00043] The transform unit determiner 12 can determine transform units having a tree structure, to transform the current encoding unit. Transformation units having a tree structure include final transformation units whose transformation results are determined for output from the transformation units of the current encoding unit.

[00044] To determine the transform units having a tree structure, the transform unit finder 12 can generate transform units from a lower level by repeatedly dividing into two equal parts the height and width of the transform unit among the transform units. transformation of the current encoding unit. The transform unit determiner 12 can determine whether to divide each transform unit into lower level transform units, independently of the other transform units at the same level as that of each transform unit.

[00045] Transformation unit determiner 12 can select transformation units from a level where a transformation error is minimized, by repeatedly transforming transformation units from each of all levels having a hierarchical structure in the current encoding unit . The transformation unit of the level allowing a minimum transformation error can be determined to be a final transformation unit whose transformation result is to be produced. Accordingly, the transmission unit determiner 12 can determine the transform units having a tree structure according to an exemplary embodiment in which the final transform units whose transform results are determined for emission are included.

[00046] Encoding unit 14 encodes the current encoding unit by generating residual data from the current encoding unit and transforming the residual data based on the transformation units determined by the transformation unit determiner 12. "Transformation" for encoding of video according to an exemplary embodiment denotes a data processing technique for transforming data from a spatial domain of a video into data from a transformation domain thereof. Examples of the transformation performed for video encoding by the encoding unit 14 may include frequency transformation, orthogonal transformation, integer transformation, and the like.

[00047] The encoded data output unit 16 produces the encoded data of the current encoding unit, information indicating an encoding mode, and transformation index information, as a bit stream.

[00048] Information about an encoding mode may include information about the various methods and the like used to encode the current encoding unit.

[00049] Transformation index information may be information about a structure of a transformation unit used to transform the current encoding unit. For example, transform index information may include the number of times the current encoding unit is split to transform into final-level transform units, and information about the sizes and shapes of the transform units.

[00050] Transformation index information can represent whether a current transformation unit is divided into transformation units of a lower level. For example, a transformation unit division bit corresponding to 1-bit data, which indicates whether a current transformation unit is divided into lower-level transformation units, can be used as transformation index information.

[00051] Transformation index information according to a first exemplary embodiment may indicate whether the current transformation unit is divided into transformation units each having the same size. For example, transformation index information according to the first exemplary embodiment may indicate whether the height and width of the current encoding unit are individually divided into two equal parts once to obtain four transformation units or are individually divided into two equal parts twice to obtain 16 transformation units. In other words, the transform index information according to the first exemplary embodiment can represent the number 4 to the power of a positive integer number of transform units individually having the same size, into which the current encoding unit is divided. .

[00052] Transformation index information according to a second exemplary embodiment may indicate whether the current encoding unit is divided into transformation units having various sizes according to a tree structure, according to an exemplary embodiment.

[00053] The size of a transform unit can be determined based on the transform index and a prediction unit type or a partition type of a current encoding unit. For example, the size of a transformation unit corresponding to the transformation index can vary according to a type of prediction unit or a type of partition of an encoding unit.

[00054] If the current transformation unit is divided into transformation units having individually the same size, the current transformation unit size can be determined based on the transformation index and a prediction unit type or a partition type of a corresponding encoding unit. Furthermore, if a current encoding unit is divided into transformation units having various sizes according to a tree structure, the size of a current transformation unit can be determined based on the transformation index and a type of unit of transformation. prediction or a partition type of the current encoding unit.

[00055] According to an exemplary embodiment, the maximum size of a transformation unit can be equal to the size of a current encoding unit. According to another exemplary embodiment, the maximum size of a transformation unit can be determined based on a prediction unit type or a partition type of a current prediction unit or partition. For example, the maximum size of the current transform unit size can indicate the size of a maximum square included in the current prediction unit or partition.

[00056] For example, the transform index information according to the second exemplary embodiment can be represented as a sequence of bits obtained by arranging transform unit division bits of transform units of respective levels that are obtained until the current encoding unit is divided into transformation units having the tree structure. The transform index information according to the second exemplary embodiment may include a sequence of bits obtained by arranging the transform unit division bits of adjacent transform units of the same level in a sequence where the transform units are scanned. in a zigzag fashion. When a predetermined transform unit may be divided into lower-level transform units having a hierarchical structure, the transform index information according to the second exemplary embodiment may include a sequence of bits obtained by arranging the unit-of-unit division bits. transformation of the lower level transform units into a sequence where the transform units are scanned in a zigzag manner.

[00057] Figure 2 is a block diagram of a video decoding equipment using a transform index, according to an exemplary embodiment.

[00058] Referring to Figure 2, the video decoding equipment using a transform index includes a receiver 22, an extractor 24, and a decoder 26. For convenience of explanation, the video decoding equipment 20 using an index of The transformation will be referred to as video decoding equipment 20. The operations of receiver 22, extractor 24 and decoder 26 of video decoding equipment 20 may be controlled by a video decoding processor (not shown), a CPU, or GPU, or similar.

[00059] To decode a current image of a received video, the video decoding equipment 20 can decode the current image by performing entropy decoding, quantization cancellation, inverse transform, and predictive decoding, including inter/compensation prediction and prediction intra/compensation, in each encoding unit of the current image.

[00060] Receiver 22 receives and analyzes a bit stream for encoded video. Extractor 24 extracts the encoded data of each encoding unit of the current image, information about an encoding mode, and transformation index information of a current encoding unit, from the bit stream analyzed by the receiver 22.

[00061] The decoder 26 decodes the encoded data by generating transformation units of the current encoding unit according to the transformation index information extracted by the extractor 24 and performs inverse transformation on the current encoding unit based on the transformation units. As a result of decoding the encoding units, the current image can be restored.

[00062] The concept of the transform unit is similar to that described above with reference to the video encoding equipment 10 of Figure 1. In other words, a transform unit according to an exemplary embodiment can be a transform unit obtained by dividing into two equal parts of the height and width of the current encoding unit or a higher-level transform unit. All transformation units included in the current encoding unit according to an exemplary embodiment may have the same size. A transformation unit according to another exemplary embodiment is a one-level transformation unit from the transformation units of the current encoding unit that has a tree structure, and can be divided into lower-level transformation units by means of repetitive division for each processing unit level or into processing units of a lower level through independent division between adjacent processing units.

[00063] The decoder 26 can read information indicating the number of times the current encoding unit is split to become final-level transform units, information about the sizes and formats of the transform units, and the like, from the transformation index information.

[00064] The decoder 26 can read information indicating whether a current transform unit is divided into lower level transform units from the transform index information.

[00065] The decoder 26 can read information indicating the level of a transform unit from a transform index according to a first exemplary embodiment. In that case, as the current encoding unit is divided into transformation units of the same sizes for each level until the transformation units of a final level are obtained, the decoder 26 can determine the transformation units of the final level having the same size. by determining the final level of the transformation units according to the transformation index and dividing into two equal parts the heights and widths of all transformation units of a higher level when the current encoding unit is divided into the transformation units of the first level.

[00066] The decoder 26 can determine the size of a transform unit based on the transform index and a prediction unit type one in a partition type of a current encoding unit. For example, the size of a transformation unit corresponding to the transformation index can vary according to a type of prediction unit or a type of partition of an encoding unit.

[00067] If the decoder 26 can divide a current encoding unit and then determine the current transform units having the same size, the current transform unit size can be determined based on the transform index and a type of unit of transformation. prediction or on a partition type of the current encoding unit. Furthermore, if a current encoding unit is divided into transformation units having various sizes according to a tree structure, a size of a current transformation unit can be determined based on the transformation index and a type of unit of transformation. prediction or a partition type of the current encoding unit.

[00068] The decoder 26 can determine the transformation units obtained according to a tree structure, based on the transformation index information according to a second exemplary embodiment. For example, a bit sequence of transform index information according to the second exemplary embodiment may be a bit sequence obtained by arranging transform unit division bits to transform units of each level. The decoder 26 can determine the transform units into which the current encoding unit is divided according to a tree structure by reading the bit sequence of transform index information according to the second exemplary embodiment and dividing the current coding so that independent division is performed between transformation units at the same level and where repetitive division is performed between levels.

[00069] At that time, the decoder 26 can read the transform unit division bits of the transform units at the same level from the transform index information according to the second exemplary embodiment and can divide the transform units into a upper level in transform units at a lower level in a sweep and zigzag sequence. When a higher-level transform unit is divided into lower-level transform units, the decoder 26 can read the transform unit division bits from the lower-level transform units, which are included in the transform unit of the lower level. top level, in a zigzag scan sequence.

[00070] The inverse transformation performed for video decoding by the decoder 26 can be referred to as a process of transforming data from a transformation domain into data from a spatial domain. Examples of the inverse transformation performed by the decoder 26 may include inverse frequency transformation, inverse orthogonal transformation, inverse integer transformation and the like.

[00071] Video encoding equipment 10 and video decoding equipment 20 can efficiently encode and decode the information used to determine the various sizes and formats of transform units having a tree structure, which are required to perform transformation and transformation inverse during video encoding and decoding based on the various sizes and formats of the encoding units, using the transform index according to an exemplary embodiment.

[00072] Figure 3 is a diagram illustrating the structure of a transformation unit and a transformation index, according to a first exemplary embodiment.

[00073] A group of transformation units 32 of level 0, a group of transformation units 34 of level 1, and a group of transformation units 36 of level 2 are illustrated according to a transformation index, as the structure of transformation unit according to the first exemplary embodiment which includes transformation units of the same sizes in order to transform a coding unit CU0 30. The transformation index according to the first exemplary embodiment may represent the number of times the transformation unit encoding CU0 30 is divided to become a group of transformation units of a current level, that is, a level number.

[00074] In other words, the level 0 transform unit 32 group includes a TU0 transform unit that is the same size as the CUO 30 coding unit by dividing the height and width of the CUO 30 coding unit zero times . In this case, the transformation index of level 0 transformation unit group 32 is 0.

[00075] The group of level 1 transformer units 34 includes transformer units TU10, TU11, TU12 and TU13, each having a height and width that are half those of the coding unit CUO 30, by dividing the height and width of the CUO 30 encoding unit once. In this case, the transformation index of level 1 transformation unit group 34 is 1.

[00076] The level 2 transformer unit group 36 includes the transformer units TU20, TU21, TU22, TU23, TU24, TU25, TU26, TU27, TU28, TU29, TU2A, TU2B, TU2C, TU2D, TU2E and TU2F each one having a height and size that are one-quarter of those of the coding unit CUO 30, by dividing the height and width of the coding unit CUO 30 twice. In that case, the transformation index of the group of transformation units 36 of level 2 is 2.

[00077] Figure 4 is a diagram illustrating the structure of a transformation unit and a transformation index, according to a second exemplary embodiment.

[00078] A group of transformation units 40 is illustrated as the transformation unit structure according to the second exemplary embodiment which includes transformation units having a tree structure for transforming the coding unit CU0 30. The transformation index of according to the second exemplary embodiment can be represented as a sequence of bits, of transform unit division bits for each level, which are used until transform units having a tree structure are obtained from the coding unit CU0 30.

[00079] In other words, as a level 0 transform unit having the same size as coding unit CU0 30, it is divided into transform units TU40, TU41, TU42 and TU43 level 1, 1 unit division bit from transformation 1 to level 1 can be generated and included in the transformation index. Since the transform unit division bits for the transform units at the same level are arranged in a zigzag scan sequence, the transform unit division bits for level 0 can be arranged in a sequence of Transform unit division bits. transformer units for the TU40, TU41, TU42 and TU43 processing units. As the TU40 and TU41 transformation units are not divided, the 0 and 0 transformation unit division bits for the TU40 and TU41 transformation units can be generated sequentially and included in the transformation index.

[00080] The TU42 level 1 transformer unit is further divided into the TU50, TU51, TU52 and TU53 level 2 transformer units. Consequently, a transformer unit 1 division bit for the TU42 level 1 transformer unit can be generated. When a transform unit of a current level is divided into transform units of a lower level, the transform unit division bits for the transform units of the lower level can be included in the transform index. Consequently, a 0-transform unit division bit for the TU50 level 2 transformation unit, a 1-transform unit division bit for the TU51 level 2 transformation unit, a 0-transform unit division bit for the TU52 level 2 transform unit, and a 0 transform unit division bit for the TU53 level 2 transform unit can be sequentially included in the transform index. The TU51 level 2 processing unit is further divided into TU60, TU61, TU62 and TU63 level 3 processing units. A level 3 processing unit is a minimum processing unit or a minimum unit, and the processing unit level 3 is not further split.

[00081] In other words, if a transformation unit division bit for a transformation unit of a current level is 1 and the transformation units of a lower level do not constitute the minimum transformation unit or the minimum unit, the bits unit-transformer division for the lower-level transformation units can be arranged consecutively after the transformation-unit division bit for the current-level unit-transformation bit.

[00082] Finally, as the TU43 level 1 transformation unit is not divided, the transformation unit division bit 0 can be included in the transformation index.

[00083] Consequently, the transform index according to the second exemplary embodiment for the coding unit CU0 30 can be determined to be 1, 0, 0, 1, 0, 1, 0, 0, 0. If the bits of transformation unit division for the transformation units of a lower level are consecutively 0, it can be understood that the transformation units of the lower level are not divided further.

[00084] The transform unit division bits generated in this way are arranged, starting from the level 0 transform unit having the same size as the encoding unit, such that the transform unit division bits of the transformation units at the same level are arranged in a zigzag scan sequence and that if a transformation unit of a predetermined level is divided into transformation units of a lower level having a hierarchical structure, the transformation unit division bits for the lower level transform units are arranged in a zigzag scan sequence, whereby the transform index according to the second exemplary embodiment can be determined.

[00085] Figures 5 and 6 are diagrams illustrating examples of use of the transformation index according to the second exemplary modality.

[00086] As described above with reference to Figure 4, if a transform unit is not further divided, the transform unit division bits are not additionally generated. Thus, the transformation index according to the second exemplary embodiment can be set according to the size of the minimum transformation unit or the minimum unit.

[00087] When the minimum transformation unit 52 of an encoding unit 50 of a size 2Nx2N has a size of NxN, the encoding unit 50 can be divided only until NxN transformation units are obtained, and thus a transformation index from encoding unit 50 to a group of transforming units 54 can be set to 1.

[00088] On the other hand, when the minimum transform unit 62 of an encoding unit 60 of a size 2Nx2N has a size of (N/2)x(N/2), transform units of a size NxN in a group of transform units 64 can be individually divided one or more times. Consequently, a transformation index from encoding unit 60 to group of transformation units 64 may include not only 1 transformation unit 1 division bit for a level 0 transformation unit, but also unit division bits of transformation 0, 0, 0 and 0 for level 1 transformation units in transformation unit group 64.

[00089] The transform units described above with reference to Figures 3 to 6 can be determined by the transform unit determiner 12 of the video encoding equipment 10, and the transform index can be encoded by the encoded data unit 14. The extractor 24 of the video decoding equipment 20 can extract the transform index information, and its decoder 26 can form a transform unit by reading the transform index, and perform inverse transform in the transform unit.

[00090] Figure 7 is a flowchart illustrating a video encoding method using a transform index, according to an exemplary embodiment.

[00091] In operation 72, a transformation unit, that is, a data unit into which a current encoding unit among the encoding units of a current image is transformed, is determined. The transform unit can be determined to be a data unit having a size less than or equal to the current encoding unit so that the transform unit is included in the current encoding unit, and the transform unit can be generated by division into two equal parts of the height and width of the encoding unit. As the transformation unit can form a hierarchical structure, the transformation units of a lower level can be generated by dividing the height and width of a transformation unit of a higher level into two equal parts. For example, all transform units of a predetermined level within a current encoding unit can be divided into transform units of a lower level, so that as many transform units of the same size as in the number of 4 to the power of a positive integer, can be generated.

[00092] The transformation unit may include final transformation units whose transformation results are determined to be produced, among the transformation units of the current encoding unit.

[00093] The hierarchical structure of the transformation units according to an exemplary embodiment can be a tree structure. Although the height and width of a current transform unit among the transform units of the current encoding unit are repeatedly divided into two equal parts, it is determined whether the division into two equal parts is performed independently of the other transform units, and so on. the transformation units of a lower level are generated. Transformation units at each level within the same region can form a hierarchical structure. Final transformation units are determined among the transformation units generated in this way so that transformation results are produced, so that transformation units having a tree structure according to an exemplary embodiment can be obtained.

[00094] The transformation units of a level where an error, due to the transformation for each transformation unit, is minimized, can be selected as the final transformation units whose transformation results are produced, by means of repeatedly performing transformation into each level for the transformation units having a hierarchical structure in the current encoding unit and comparing the transformation results with each other.

[00095] In operation 74, the current encoding unit is encoded, including transformation based on the transformation unit. In operation 76, the encoded data of the current encoding unit, information about an encoding mode, and transformation index information are produced.

[00096] Transformation index information on the structure of a transformation unit according to an exemplary modality can indicate whether a current transformation unit is divided into transformation units of a lower level. Transformation index information about the structure of a transformation unit according to an exemplary embodiment may include the number of times the current encoding unit is split to transform into final-level transformation units, and the information on the sizes and formats of the processing units.

[00097] The transformation index information according to a first exemplary embodiment may indicate a level that identifies the total number of division times from a current encoding unit to a final level encoding unit. Transform units at each level can be the same sizes.

[00098] Transformation index information according to a second exemplary embodiment may indicate whether the current encoding unit is repeatedly split to obtain transformation units having a tree structure. The transformation index information according to the second exemplary embodiment may be in the form of a sequence of bits obtained by arranging transformation unit division bits which indicate whether a transformation unit of each level is divided into transformation units of a lower level. The transform index information bit sequence can be obtained by arranging the transform unit division bits of adjacent transform units of the same level in a sequence where the transform units are scanned in a zigzag fashion. When a current transform unit includes transform units of a lower level having a hierarchical structure, a sequence of transform index information bits can be determined so that the transform unit division bits of the transform units of a level bottom are arranged in a sequence where the transformation units are scanned in a zigzag fashion.

[00099] Figure 8 is a flowchart illustrating a video decoding method using a transform index, according to an exemplary embodiment.

[000100] In operation 82, a bit stream for an encoded video is received and parsed.

[000101] In operation 84, the encoded data of a current encoding unit of a current image, information about an encoding mode, and transformation index information are extracted from the analyzed bit stream.

[000102] In operation 86, inverse transformation is performed on the current encoding unit, based on the transformation units obtained according to the transformation index information, and thus the encoded data is decoded. As a result of decoding each encoding unit, the current image can be restored. If a current transformation unit is divided into transformation units of a lower level and can be read based on transformation index information about the structure of a transformation unit according to an exemplary modality, and the transformation units can be determined. The inverse transformation in the current encoding unit can be performed based on the transformation units.

[000103] The number of times the current encoding unit is split until the final level transform units are obtained, and information about the sizes, shapes, and the like, of the transform units can be read from the information of transformation index on the structure of a transformation unit according to an exemplary embodiment.

[000104] A level indicating the total number of times of division from the current encoding unit to a final level transformation unit can be read from the transformation index information according to the first exemplary embodiment. The level of a transformation unit indicates the number of times the current encoding unit is divided to obtain 4 information units all of which are the same size. Consequently, a structure of transformation units into which the current encoding unit is divided into transformation units having individually the same size can be determined.

[000105] A bit sequence of transform unit division bits that indicates whether a transform unit of each level is divided into transform units of a lower level is read from the transform index information according to the second exemplary mode, until the current encoding unit is split repeatedly to obtain transformation units having the tree structure. Thus, a structure of the transformation units into which the current encoding unit is divided according to the tree structure can be determined.

[000106] For example, the transformation unit division bits of adjacent transformation units at the same level, among the transformation index information according to the second exemplary embodiment, can be read in a sequence where the transformation units are scanned in a zigzag fashion. Furthermore, the transformation unit division bits of the transformation units of a lower level having a hierarchical structure included in a transformation unit of a predetermined level, from the transformation index information according to another exemplary embodiment, may be read in a sequence where the lower level transform units are scanned in a zigzag fashion.

[000107] First, a method and apparatus for encoding video using an encoding unit having a tree structure and a transform index, and a method and apparatus for decoding video using an encoding unit having a tree structure and a transformation index, according to an exemplary embodiment, will be described with reference to Figures 9 to 23.

[000108] Figure 9 is a block diagram of a video encoding apparatus 100 that uses a transform index based on encoding units and transforming units having a tree structure, according to an exemplary embodiment.

[000109] The video encoding equipment 100, which uses the transform index based on encoding units and transmission units having a tree structure, includes a maximum encoding unit divider 110, an encoding unit determiner 120, and an output unit 130. For convenience of explanation, video encoding equipment 100, which uses the transform index based on encoding units and transmission units having a tree structure, is referred to as equipment. of video encoding 100.

[000110] Maximum encoding unit splitter 110 can divide a current image based on a maximum encoding unit for the current frame of an image. The current frame is larger than the maximum encoding unit, the image data of the current frame can be divided into at least one maximum encoding unit. The maximum encoding unit according to an exemplary embodiment may be a data unit having a size of 32x32, 64x64, 128x128, 256x256, etc., wherein a format of the data unit is a square having a width and height in squares. of 2. The image data may be output to the encoding unit determiner 120 according to at least one maximum encoding unit.

[000111] A coding unit according to an exemplary embodiment can be characterized by a maximum size and a depth. Depth denotes a number of times the encoding unit is spatially divided from the maximum encoding unit, and as the depth is deepened or increased, deeper encoding units, according to the depths, can be divided. from the maximum encoding unit to a minimum encoding unit. A maximum encoding unit depth is a higher depth and a minimum encoding unit depth is a lower depth. As the size of an encoding unit corresponding to each depth decreases as the depth of the maximum encoding unit is deepened, an encoding unit corresponding to a higher depth may include a plurality of encoding units corresponding to lower depths.

[000112] As described above, the current frame image data is divided into maximum encoding units according to a maximum encoding unit size, and each of the maximum encoding units can include deeper encoding units which are divided according to depths. As the maximum encoding unit according to an exemplary embodiment is divided according to depths, the image data of a spatial domain included in the maximum encoding unit can be hierarchically classified according to depths.

[000113] A maximum depth and maximum size of an encoding unit, which limit the total number of times the height and width of the maximum encoding unit are hierarchically divided, can be predetermined.

[000114] The encoding unit determiner 120 encodes at least one divided region obtained by dividing a region of the maximum encoding unit according to depths, and determines a depth to output the finally encoded image data according to the at least depth. least one split region. In other words, the encoding unit determiner 120 determines an encoded depth by encoding the image data in the deepest encoding units according to the depths, in accordance with the maximum encoding unit of the current frame, and selects a depth having the smallest coding error. Thus, the encoded image data of the encoding unit corresponding to the determined encoded depth is finally produced. Furthermore, the encoding units corresponding to the encoded depth can be considered as encoded encoding units.

[000115] The determined coded depth and the encoded image data according to the determined coded depth is output to the output unit 130.

[000116] The image data in the maximum encoding unit is encoded based on the deepest encoding units corresponding to at least a depth equal to or below the maximum depth, and the encoding results of the image data are compared based on each one of the deepest encoding units. A depth having the smallest encoding error can be selected after comparing the encoding errors of the deepest encoding units. At least one coding depth can be selected for each maximum coding unit.

[000117] The maximum encoding unit size is divided as an encoding unit is divided hierarchically according to depths, and as the number of encoding units increases. Furthermore, even if the coding units correspond to the same depth in a maximum coding unit, it is determined whether to divide each of the coding units corresponding to the same depth to a lesser depth by decreasing a coding error of the image data of each encoding unit separately. Consequently, even when the image data is included in a maximum encoding unit, the image data is divided into regions according to depths, and encoding errors may differ according to the regions in that maximum encoding unit, and so encoded depths may differ according to regions in the image data. Thus, one or more coded depths can be determined in a maximum coding unit, and the image data of the maximum coding unit can be divided according to the coding units of at least one coded depth.

[000118] Accordingly, the coding unit determiner 120 can determine the coding units which have a tree structure included in the maximum coding unit. Encoding units having a tree structure according to an exemplary embodiment include encoding units corresponding to a depth determined to be the encoded depth, from all the deepest encoding units included in the maximum encoding unit. An encoding unit of an encoded depth can be determined hierarchically according to depths in the same region as the maximum encoding unit, and can be independently determined in different regions. Similarly, a depth encoded in a current region can be determined independently of a depth encoded in another region.

[000119] A maximum depth according to an exemplary embodiment is an index related to the number of times of division from a maximum encoding unit to a minimum encoding unit, that is, the number of times the maximum encoding unit is divided into a minimal encoding unit. A first maximum depth according to an exemplary embodiment may denote the total number of division times from the maximum encoding unit to the minimum encoding unit. A second maximum depth according to an exemplary embodiment may denote the total number of depth levels from the maximum encoding unit to the minimum encoding unit. For example, when the maximum encoding unit depth is zero, a depth of one encoding unit, into which the maximum encoding unit is divided once, can be set to 1, and a depth of one encoding unit; in which the maximum encoding unit is divided twice; can be set to 2. Here, if the minimum encoding unit is an encoding unit in which the maximum encoding unit is divided four times, there are 5 levels of depth, of depth 0, 1, 2, 3 and 4, and so the first maximum depth can be set to 4, and the second maximum depth can be set to 5.

[000120] Prediction encoding and transformation can be performed according to the maximum encoding unit. Predictive coding and transformation are also performed based on the deepest coding units according to a depth equal to, or depths less than, the maximum depth according to the maximum coding unit. The transformation can be performed according to an orthogonal transformation method or an integer transformation.

[000121] As the number of deepest encoding units increases whenever the maximum encoding unit is divided according to depths; coding including prediction coding and transformation is performed on all units and deeper coding generated as depth is deepened. For convenience of description, the prediction encoding and transformation will now be described based on an encoding unit of a current depth, into a maximum encoding unit.

[000122] The video encoding equipment 100 can variably select a size or format of a data unit to encode the image data. To encode the image data, operations such as prediction encoding, transformation, and entropy encoding are performed at which time, the same data unit can be used for all operations or different data units can be used for each operation. .

[000123] For example, the video encoding equipment 100 can select not only an encoding unit to encode the image, but also a data unit other than the encoding unit in order to perform prediction encoding on the image data in the encoding unit.

[000124] To perform prediction coding on the maximum coding unit, prediction coding can be performed on the basis of a coding unit corresponding to a coded depth, i.e. based on a coding unit which is no longer divided into an encoding unit corresponding to a lower depth. Then, the encoding unit that is no longer split and becomes a base unit for prediction encoding will now be referred to as a prediction unit. A partition obtained by dividing the prediction unit may include a prediction unit or a data unit obtained by dividing at least one of a height and a width of the prediction unit.

[000125] For example, when an encoding unit of 2Nx2N (where N is a positive integer) is no longer divided and becomes a prediction unit of 2Nx2N, and a partition size can be 2Nx2N, 2NxN, Nx2N, or NxN. Examples of a partition type include symmetric partitions that are obtained simply by dividing a prediction unit's height or width, partitions obtained by asymmetrically dividing the prediction unit's height or width, such as 1:n or n:1, partitions which are obtained by geometric division of the prediction unit, and partitions which have arbitrary formats.

[000126] A prediction mode of the prediction unit can be at least one of: an intra mode, an inter mode, and a jump mode. For example, intra-mode or inter-mode can be performed on the partition of 2Nx2N, 2NxN, Nx2N, or NxN. Also, jump mode can only be performed on 2Nx2N partition. Encoding is performed independently on a prediction unit in an encoding unit, thereby selecting a prediction mode that has the smallest encoding error.

[000127] The video encoding equipment 100 can also perform the transformation on the image data in an encoding unit based not only on the encoding unit to encode the image data, but also on the basis of the data unit which is different of the encoding unit.

[000128] As described above with reference to Figures 1 to 8, to perform the transformation on the encoding unit, the transformation can be performed on the basis of a data unit that has a size less than or equal to that of the encoding unit. For example, the data unit for the transformation may include a data unit for an intra mode and a data unit for an inter mode.

[000129] A data unit used as a base of the transformation will now be referred to as a “transformation unit”. A transform depth indicating the number of division times to reach the transform unit by dividing the coding unit height and width can be set in the transform unit. For example, in a current encoding unit of 2Nx2N, a transform depth can be 0 when the size of a transform unit is also 2Nx2N, it can be 1 when each of the height and width of the current encoding unit is divided into two equal parts, divided fully into 4A1 transform units, and the size of transform unit is thus NxN, and it can be 2 when each of the current encoding unit's height and width is divided into four equal parts, fully divided into 4A1 units of transformation and the size of the transformation units is thus N/2xN/2. For example, the transformation unit can be adjusted according to a hierarchical tree structure, in which one transformation unit, of a higher transformation depth, is divided into four transformation units of a lower transformation depth, according to the hierarchical characteristics of a transformation depth.

[000130] Similar to the encoding unit, the transform unit in the encoding unit can be recursively divided into smaller sized regions, so that the transform unit can be independently determined in region units. Thus, the residual data in the encoding unit can be split according to the transformation having the tree structure according to the transformation depths.

[000131] Encoding information according to encoding units corresponding to an encoded depth requires not only information about the encoded depth, but also information related to encoding prediction and transformation. Consequently, the encoding unit determiner 120 not only determines an encoded depth having a smaller encoding error, but also determines a partition type in a prediction unit, a prediction mode according to prediction units, and a size. of a processing unit for processing.

[000132] Encoding units according to a tree structure in a maximum encoding unit and a method of determining a partition, according to exemplary embodiments, will be described in detail later with reference to Figures 11 and 12.

[000133] Encoding unit determiner 120 can measure a coding error of deeper coding units according to depths by using Rate-Distortion Optimization based on Lagrangian multipliers.

[000134] The output unit 130 outputs the image data of the maximum encoding unit, which is encoded based on the lowest encoded depth determined by the encoding unit determiner 120, and information about the encoding mode according to the depth. encoded, in bitstreams.

[000135] Encoded image data can be obtained by encoding the residual data of an image.

[000136] Information about the encoding mode according to the encoded depth may include information about the encoded depth, about the type of partition in the prediction unit, the prediction mode, and the size of the transformation unit.

[000137] The encoded depth information can be defined using information divided according to depths, which indicates whether encoding is performed in encoding units of a lower depth rather than an actual depth. If the current depth of the current encoding unit is the encoded depth, the image data in the current encoding unit is encoded and output, and so the split information can be set not to split the current encoding unit to a lower depth. Alternatively, if the current depth of the current encoding unit is not the encoded depth, encoding is performed in the encoding unit of the lowest depth, and so the divided information can be set to divide the current encoding unit to obtain the encoding units of the lowest depth. lowest depth encoding.

[000138] If the current depth is not the encoded depth, encoding is performed in the encoding unit which is divided into the lowest depth encoding unit. As there is at least one lowest depth encoding unit in a current depth encoding unit, encoding is performed repeatedly on each lowest depth encoding unit, and thus encoding can be performed recursively for the lowest depth encoding units. encoding that have the same depth.

[000139] As encoding units having a tree structure are determined for a maximum encoding unit, and information about at least one encoding mode is determined for a encoding unit of a coded depth, information about at least one encoding mode encoding can be set to a maximum encoding unit. Furthermore, an encoded depth of the image data of the maximum encoding unit may be different according to the locations since the image data is hierarchically divided according to the depths, and thus the encoded depth and mode information encoding can be adjusted for the image data.

[000140] Accordingly, the output unit 130 can assign encoding information about a corresponding encoding depth and encoding mode to at least one of encoding unit, prediction unit, and a minimum unit included in the maximum encoding unit.

[000141] The minimum unit according to an exemplary embodiment is a rectangular data unit obtained by dividing by 4 the minimum encoding unit constituting the lowest depth. Alternatively, the minimum unit may be a maximum rectangular data unit that can be included in all encoding units, prediction units, partition units, and transformation units included in the maximum encoding unit.

[000142] For example, the coding information output through the output unit 130 can be classified into coding information according to the coding units, and coding information according to the prediction units. The coding information according to the coding units may include information about the prediction mode and about the size of the partitions. The coding information according to the prediction units may include information about an estimated direction in an inter mode, about a reference image index of the inter mode, about a motion vector, about a chroma component in an intra mode, and about an intra mode interpolation method. In addition, information about a maximum size of the encoding unit defined according to illustrations, slices, or GOPs, and information about a maximum depth can be entered into an SPS (Sequence Parameter Set) or a bitstream header. . Additionally, the output of encoding information through output unit 130 may include transformation index information about a structure of a transformation unit according to an exemplary embodiment, as described above with reference to Figures 1 to 8.

[000143] In the video encoding equipment 100, the deepest encoding unit may be an encoding unit obtained by dividing a height or width of a higher depth encoding unit, which is one layer above, by two. In other words, when the current depth encoding unit size is 2Nx2N, the bottom depth encoding unit size is NxN. Also, the current depth coding unit having the size of 2Nx2N can include a maximum of 4 of the lower depth coding units.

[000144] Consequently, the video encoding equipment 100 can form the encoding units having the tree structure by determining the encoding units having an optimal size and an optimal size for each maximum encoding unit, based on the unit size maximum encoding and the maximum depth determined considering the characteristics of the current frame. Furthermore, as encoding can be performed on each maximum encoding unit using any of several prediction and transformation modes, an optimal encoding mode can be determined by considering encoding unit characteristics of various image sizes.

[000145] Thus, if an image having high resolution or large amount of data is encoded in a conventional macroblock, the number of macroblocks per frame increases excessively. Consequently, a number of pieces of compressed information generated for each macroblock increases, and so it is difficult to transmit the compressed information and the efficiency of data compression decreases. However, by using the video encoding equipment 100, the image compression efficiency can be increased once an encoding unit is adjusted while considering the characteristics of an image while increasing a maximum size of an encoding unit while considering a image size.

[000146] Figure 10 is a block diagram of a video decoding apparatus 200 using encoding units having a tree structure and a transform index, according to an exemplary embodiment.

[000147] Video decoding equipment 200 includes a receiver 210, an image data and encoding information extractor 220, and an image data decoder 230. Definitions of various terms, such as an encoding unit, a depth, a prediction unit, a transform unit, and information about various encoding modes, for various operations of the video decoding equipment 200 are identical to those described with reference to Figure 9 and the video encoding equipment 100.

[000148] Receiver 210 receives and analyzes an encoded video bit stream. The coding information and image data extractor 220 extracts the coded image data for each coding unit from the analyzed bit stream, wherein the coding units have a tree structure according to each maximum coding unit, and outputs the extracted image data to the image data decoder 230. The encoding information and image data extractor 220 can extract information about a maximum size of an encoding unit of a current frame from a header about the current frame or SPS.

[000149] In addition, the coding information and image data extractor 220 extracts information about an coded depth and an coding mode for the coding units having a tree structure according to each maximum coding unit, from the parsed bit stream. The extracted information about the encoded depth and encoding mode is output to the image data decoder 230. In other words, the image data in a bit stream is split to the maximum encoding unit so that the image data decoder image data 230 decodes the image data for each maximum encoding unit.

[000150] Information about the encoded depth and encoding mode according to the maximum encoding unit may be set to information about at least one encoding unit corresponding to the encoded depth, and information about an encoding mode may include information about a partition type of a corresponding encoding unit, corresponding to the encoded depth, over a prediction mode, and a transformation unit size. Furthermore, information divided according to depths can be extracted as encoded depth information. Additionally, the image data encoding information extractor 220 can extract transformation index information about a structure of a transformation unit according to an embodiment as described above with reference to Figures 1 to 8 as the extracted information about the encoded depth and encoding mode.

[000151] The information about the encoded depth and the encoding mode according to each maximum encoding unit extracted by the image data and encoding information extractor 220 is information about an encoded depth and an encoding mode determined to generate an error of minimum encoding when an encoder, such as video encoding equipment 100, repeatedly performs encoding for each deeper encoding unit according to depths according to each maximum encoding unit. Accordingly, the video decoding apparatus 200 can restore an image by decoding the image data according to an encoded depth and an encoding mode that generates the minimum encoding error.

[000152] As encoding information about the encoded depth and encoding mode can be assigned to a predetermined data unit among a corresponding encoding unit, a prediction unit, and a minimum unit, the encoding information extractor and image data 220 can extract the information about the encoded depth and the encoding mode according to predetermined data units. The predetermined data units to which the same information about the encoded depth and encoding mode is assigned can be inferred to be the data unit included in the same maximum encoding unit.

[000153] The picture data decoder 230 restores the current frame by decoding the picture data in each maximum encoding unit based on the information about the encoded depth and the encoding mode according to the maximum encoding units. In other words, the image data decoder 230 can decode the decoded image data based on the extracted information about the partition type, prediction mode, and transformation unit for each encoding unit among the encoding units that have the tree structure included in each maximum encoding unit. A decoding process may include a prediction including intra prediction and motion compensation, and an inverse transformation. The inverse transformation can be performed according to the inverse orthogonal transformation or inverse integer transformation method.

[000154] The picture data decoder 230 can perform intra prediction or motion compensation according to a partition and a prediction mode of each encoding unit, based on the information about the partition type and the prediction mode of the unit of prediction of the encoding unit according to the encoded depths.

[000155] In addition, the picture data decoder 230 can perform inverse transformation according to each transform unit in the encoding unit, based on information about the transform unit size of the encoding unit according to the encoded depths , in order to perform the inverse transformation according to the maximum encoding units.

[000156] The picture data decoder 230 can determine at least an encoded depth of a current maximum encoding unit by using information divided according to the depths. If the split information indicates that the image data is no longer split at the current depth, the current depth is an encoded depth. Accordingly, the picture data decoder 230 can decode the encoded data of at least one encoding unit corresponding to each encoded depth in the current maximum encoding unit by using information about the partition type of the prediction unit, the prediction mode , and the transform unit size for each encoding unit corresponding to the encoded depth, and output the image data of the current maximum encoding unit.

[000157] In other words, the data units containing the encoding information including the same divided information can be compiled by observing the set of encoding information assigned to the predetermined data unit from among the encoding unit, the prediction unit, and the minimum unit, and the compiled data units may be considered to be a data unit to be decoded by the picture data decoder 230 in the same encoding mode.

[000158] The video decoding equipment 200 can obtain information about at least one encoding unit that generates the minimum encoding error when encoding is performed recursively for each maximum encoding unit, and can use the information to decode the current image. In other words, encoding units having the tree structure determined to be the optimal encoding unit at each maximum encoding unit can be decoded. Also, the maximum size of the encoding unit is determined considering the resolution and an amount of image data.

[000159] Consequently, even if the image data has high resolution and a large amount of data, the image data can be efficiently decoded and restored by using an encoding unit size and encoding mode, which are adaptively determined according to the characteristics of the image data, using information about an optimal encoding mode received from an encoder.

[000160] A method of determining encoding units having a tree structure, a prediction unit, and a transform unit, according to an exemplary embodiment, will now be described with reference to Figures 11 to 21.

[000161] Figure 11 is a diagram to describe a concept of hierarchical coding units according to an exemplary embodiment.

[000162] A size of an encoding unit can be expressed in width x height, and can be 64x64, 32x32, 16x16 and 8x8. A 64x64 encoding unit can be divided into 64x64, 64x32, 32x64 or 32x32 partitions, and a 32x32 encoding unit can be divided into 32x32, 32x16, 16x32, or 16x16 partitions, a 16x16 encoding unit can be divided into 16x16, 16x8, 8x16 or 8x8 partitions, and an 8x8 encoding unit can be divided into 8x8, 8x4, 4x8 or 4x4 partitions.

[000163] In 310 video data, a resolution is 1920x1080, a maximum size of an encoding unit is 64, and a maximum depth is 2. In 320 video data, a resolution is 1920x1080, a maximum size encoding is 64, and a maximum depth is 3. In video data 330, a resolution is 352x288, a maximum size of an encoding unit is 16, and a maximum depth is 1. The maximum depth shown in Figure 3 denotes a total number of divisions from a maximum encoding unit to a minimum decoding unit.

[000164] If the resolution is high or the amount of data is large, a maximum size of an encoding unit can be so large as to not only increase encoding efficiency, but also accurately reflect the characteristics of a Image. Accordingly, the maximum size of encoding unit of video data 310 and 320 having higher resolution than video data 330 can be 64.

[000165] As the maximum depth of video data 310 is 2, encoding units 315 of video data 310 may include a maximum encoding unit having a long axis size of 64, and encoding units having axis sizes lengths of 32 and 16 as the depths are deepened to two layers by dividing the maximum encoding unit twice. However, since the maximum depth of video data 330 is 1, encoding units 335 of video data 330 may include a maximum encoding unit having a long axis size of 16, and encoding units having an axis size of 16. along 8 as depths are deepened for one layer by dividing once from the maximum encoding unit.

[000166] As the maximum depth of video data 320 is 3, encoding units 325 of video data 320 may include a maximum encoding unit having a long axis size of 64, and encoding units having axis sizes along 32, 16 and 8 as the depths are deepened to 3 layers by dividing the maximum encoding unit three times. As depth is deepened, detailed information can be accurately expressed.

[000167] Figure 12 is a block diagram of an image encoder 400 based on encoding units, according to an exemplary embodiment.

[000168] The image encoder 400 performs operations of the encoding unit determiner 120 of the video encoding equipment 100 to encode the image data. In other words, an intra predictor 410 performs intra prediction on the coding units in an intra mode, within a current frame 405, and a motion estimator 420 and a motion compensator 425 performs inter-estimation and motion compensation on the coding units. in an inter-mode within the current frame 405 by using the current frame 405, and a reference frame 495.

[000169] Data output from the intra predictor 410, motion estimator 420, and motion compensator 425 is output as a quantized transform coefficient through transformer 430 and a quantizer 440. The quantized transform coefficient is restored as data in a spatial domain through an inverse quantizer 460 and an inverse transformer 470, and the restored data in the spatial domain is output as the reference frame 495 after being post-processed through an unblocking unit 480 and a filtering unit 495. loop 490. The quantized transform coefficient can be output as a stream of bits 455 through an entropy encoder 450.

[000170] In order for the image encoder 400 to be applied to the video encoding equipment 100, all elements of the image encoder 400, i.e. the intra predictor 410, the motion estimator 420, the motion compensator 425, the transformer 430, quantizer 440, entropy encoder 450, inverse quantizer 460, inverse transformer 470, unblocking unit 480, and loop filtering unit 490 perform operations based on each encoding unit among encoding units having a tree structure while considering the maximum depth of each maximum encoding unit.

[000171] Specifically, the intra predictor 410, the motion estimator 420, and the motion compensator 425 determine partitions and a prediction mode of each encoding unit among encoding units having a tree structure while considering the maximum size and the maximum depth of a current maximum coding unit, and transformer 430 determines the size of the transform unit in each coding unit among the coding units having a tree structure.

[000172] Figure 13 is a block diagram of a picture decoder 500 based on encoding units, according to an exemplary embodiment.

[000173] An analyzer 510 analyzes the encoded image data to be decoded and encoding information required for decoding from a bit stream 505. The encoded image data is output as inverse quantized data through an entropy decoder 520 and an inverse quantizer 530, and the inverse quantized data is restored to image data in a spatial domain through an inverse transformer 540.

[000174] An intra predictor 550 performs intra prediction on coding units in an intra mode with respect to image data in the spatial domain, and a motion compensator 560 performs motion compensation on coding units in an inter mode by using a frame of reference 585.

[000175] The image data in the spatial domain, which has passed through the intra predictor 550 and the motion compensator 560, can be output as a restored frame 595 after being post-processed through an unblocking unit 570 and a deblocking unit 570. loop filtering 580. In addition, image data that is post-processed through deblocking unit 570 and loop filtering unit 580 can be output as reference frame 585.

[000176] To decode the image data in the image data decoder 230 of the video decoding equipment 200, the image decoder 500 can perform operations that are performed after the analyzer 510.

[000177] In order for the picture decoder 500 to be applied to the video decoding equipment 200, all elements of the picture decoder 500, i.e. the analyzer 510, the entropy decoder 520, the inverse quantizer 530, the inverse transformer 540, intrapredictor 550, motion compensator 560, unlocking unit 570, and loop filtering unit 580 perform operations based on encoding units having a tree structure for each maximum encoding unit.

[000178] Specifically, intra prediction 550 and motion compensator 560 perform operations based on partitions and a prediction mode for each of the encoding units having a tree structure, and inverse transformer 540 perform operations based on a size of one transform unit for each encoding unit.

[000179] Figure 14 is a diagram illustrating deeper encoding units according to depths, and partitions, according to an exemplary embodiment.

[000180] Video encoding equipment 100 and video decoding equipment 200 use hierarchical encoding units in order to account for the characteristics of an image. A maximum height, a maximum width, and a maximum depth of the encoding units can be adaptively determined according to the image characteristics, or they can be adjusted differently by a user. Deeper encoding unit sizes, according to the depths, can be determined according to the predetermined maximum encoding unit size.

[000181] In a hierarchical structure 600 of encoding units, according to an exemplary embodiment, the maximum height and maximum width of the encoding units are individually 64, and the maximum depth is 4. along a vertical axis of the hierarchical structure 600, a height and width of the deepest encoding unit are individually divided. In addition, a prediction unit and the partitions, which are the basis for encoding prediction of each deeper encoding unit, are shown along a horizontal axis of the hierarchical structure 600.

[000182] In other words, an encoding unit 610 is a maximum encoding unit in the hierarchical structure 600, where a depth is 0 and a size, that is, a height per width, is 64x64. The depth is deepened along the vertical axis, and there is an encoding unit 620, having a size of 32x32, and a depth of 1; an encoding unit 630, having a size of 16x16, and a depth of 2; a coding unit 640, having a size of 8x8, and a depth of 3; and an encoding unit 650 having a size of 4x4 and a depth of 4. Encoding unit 650 having a size of 4x4 and a depth of 4 is a minimum encoding unit.

[000183] The prediction unit and the partitions of an encoding unit are arranged along the horizontal axis according to each depth. In other words, if the coding unit 610, having the size of 64x64, and the depth of 0, is a prediction unit, the prediction unit can be divided into partitions included in the coding unit 610, that is, a partition 610 having a size of 64x64, partitions 612 having a size of 64x32, partitions 614 having a size of 32x64, or partitions 616 having a size of 32x32.

[000184] Similarly, a prediction unit of encoding unit 620 having a size of 32x32 and a depth of 1 can be divided into partitions included in encoding unit 620, i.e., a partition 620 having a size of 32x32, partitions 622 having a size of 32x16, partitions 624 having a size of 16x32, and partitions 626 having a size of 16x16.

[000185] Similarly, a prediction unit of encoding unit 630 having a size of 16x16 and a depth of 2 can be divided into partitions included in encoding unit 630, that is, a partition having a size of 16x16 included in the encoding unit 630. encoding 630, partitions 632 having a size of 16x8, partitions 634 having a size of 8x16, and partitions 636 having a size of 8x8.

[000186] Similarly, a prediction unit of encoding unit 640 having a size of 8x8 and a depth of 3 can be divided into partitions included in encoding unit 640, i.e., a partition having a size of 8x8 included in the encoding unit. encoding 640, partitions 642 having a size of 8x4, partitions 644 having a size of 4x8, and partitions 646 having a size of 4x4.

[000187] Encoding unit 650 having a size of 4x4 and a depth of 4 is the minimum encoding unit and an encoding unit of the lowest depth. A prediction unit of encoding unit 650 is assigned only to a partition having a size of 4x4.

[000188] To determine the at least one coded depth of the coding units constituting the maximum coding unit 610, the coding unit determiner 120 of the video coding equipment 100 performs coding for the coding units corresponding to each depth included in the maximum encoding unit 610.

[000189] A number of deeper encoding units, according to depths including data in the same range and in the same size, increases as the depth is deepened. For example, four encoding units corresponding to a depth of 2 are required to cover the data that is included in one encoding unit corresponding to a depth of 1. Accordingly, to compare encoding results of the same data according to depths , the encoding unit corresponding to the depth of 1; and four encoding units corresponding to the depth of 2; are individually coded.

[000190] To perform coding for a current depth between depths, a minimum coding error can be selected for the current depth by performing coding for each prediction unit in the coding units corresponding to the current depth, along the horizontal axis of the hierarchical structure 600. Alternatively, the minimum coding error can be searched by comparing the minimum coding errors according to the depths, by performing coding for each depth as the depth is deepened along the vertical axis of the hierarchical structure 600. A depth and partition having the minimum encoding error in encoding unit 610 can be selected as the encoded depth and a partition type of encoding unit 610.

[000191] Figure 15 is a diagram for describing a relationship between an encoding unit 710 and transforming units 720, according to an exemplary embodiment.

[000192] Video encoding equipment 100 or 200 encodes or decodes an image according to encoding units having sizes less than or equal to one maximum encoding unit for each maximum encoding unit. Transform unit sizes for transformation during encoding can be selected based on data units that are not larger than a corresponding encoding unit.

[000193] For example, in video encoding equipment 100 or 200, if a size of the encoding unit 710 is 64x64, the transformation can be performed using transformation units 720 having a size of 32x32.

[000194] In addition, data from encoding unit 710 having the size of 64x64 can be encoded by performing the transformation on each of the transforming units having the size of 32x32, 16x16, 8x8, and 4x4, which are smaller than 64x64, and then a transform unit having the minimum encoding error can be selected.

[000195] Figure 16 is a diagram for describing encoding information of encoding units corresponding to an encoded depth, according to an exemplary embodiment.

[000196] Output unit 130 of video encoding equipment 100 can encode and transmit information 800 about a partition type, information 810 about a prediction mode, and information 820 about a size of a transform unit for each unit of encoding corresponding to an encoded depth, as information about an encoding mode.

[000197] Information 800 indicates information about a format of a partition obtained by dividing a prediction unit from a current encoding unit, wherein the partition is a data unit for predicting encoding from the current encoding unit. For example, a current encoding unit CU_0 having a size of 2Nx2N can be split into any one of a partition 802 having a size of 2Nx2N, an 804 partition having a size of 2NxN, a partition of 806 having a size of Nx2N, and an 808 partition having a size of NxN. Here, information 800 about a partition type is set to indicate one of partition 804 having a size of 2NxN, partition 806 having a size of Nx2N, and partition 808 having a size of NxN.

[000198] Information 810 indicates a prediction mode for each partition. For example, information 810 may indicate a prediction encoding mode performed on a partition indicated by information 800, i.e., an intra mode 812, an inter mode 814, or a hop mode 816.

[000199] Information 820 indicates a unit of transformation to be based on when the transformation is performed on a current encoding unit. For example, the transform unit can be a first intra transform unit 822, a second intra transform unit 824, a first inter transform unit 826, or a second intra transform unit 828.

[000200] Image data and encoding information extractor 220 of video decoding equipment 200 can extract and use information 800, 810 and 820 for decoding, according to each deeper encoding unit.

[000201] Figure 17 is a diagram of deeper encoding units according to depths, according to an exemplary embodiment.

[000202] Split information can be used to indicate a change of a depth. Split information indicates whether an encoding unit of a current depth is divided into encoding units of a lower depth.

[000203] A prediction unit 910 for encoding prediction of an encoding unit 900 having a depth of 0 and a size of 2N_0x2N_0 may include partitions of a partition type 912 having a size of 2N_0x2N_0, a partition type 914 having a size of 2N_0xN_0, a partition type 916 having a size of N_0x2N_0, and a partition type 918 having a size of N_0xN_0. Figure 9 only illustrates the partition types 912 to 918 which are obtained by symmetrical division of the prediction unit 910, however a partition type is not limited to that, and the partitions of the prediction unit 910 can include asymmetric partitions, partitions having a predetermined shape and partitions having a geometric shape.

[000204] The prediction coding is performed repeatedly on one partition having a size of 2N_0x2N_0, two partitions having a size of 2N_0xN_0, two partitions having a size of N_0x2N_0, and four partitions having a size of N_0xN_0, according to each partition type. Prediction encoding in an intra mode and an inter mode can be performed on partitions having sizes of 2N_0x2N_0, N_0x2N_0, 2N_0xN_0 and N_0xN_0. Prediction encoding in a jump mode is performed only on the partition having the size of 2N_0x2N_0.

[000205] Encoding errors including prediction encoding in partition types 912 to 918 are compared, and the minimum encoding error is determined between partition types. If an encoding error is minor on one of partition types 912 to 916, then the prediction unit 910 may not be split to a lower depth.

[000206] If the encoding error is the smallest in partition type 918, a depth is changed from 0 to 1 to divide partition type 918 in operation 920, and encoding is performed repeatedly in encoding units 930 having a depth of 2 and a size of N_0xN_0 to look for a minimal encoding error.

[000207] A prediction unit 940 for encoding prediction encoding unit 930 having a depth of 1 and a size of 2N_1x2N_1(=N_0xN_0) may include partitions of a partition type 942 having a size of 2N_1x2N_1, a partition type 944 having a size of 2N_1xN_1, a partition type 946 having a size of N_1x2N_1, and a partition type 948 having a size of N_1xN_1.

[000208] If an encoding error is the smallest in partition type 948, a depth is changed from 1 to 2 to divide partition type 948 in operation 950, and encoding is performed repeatedly in encoding units 960, which have a depth of 2 and a size of N_2xN_2 to look for minimal encoding error.

[000209] When a maximum depth is d, the division operation according to each depth can be performed even when a depth becomes d-1; and the split information can be encoded even when a depth is one from 0 to d-2. In other words, when encoding is performed up to when the depth is d-1 after a encoding unit corresponding to a depth of d-2 is divided in operation 970, a prediction unit 990 for encoding prediction of a encoding unit 980 having a depth of d-1 and a size of 2N_(d-1)x2N_(d-1) may include partitions of a partition type 992 having a size of 2N_(d-1)x2N_(d-1), a partition type 994 having a size of 2N_(d-1)xN_(d-1), a partition type 996 having a size of N_(d-1)x2N_(d-1), a partition type 998 having a size of N_(d-1)xN_(d-1).

[000210] Prediction coding can be performed repeatedly on one partition having a size of 2N_(d-1)x2N_(d-1), two partitions having a size of 2N_(d-1)xN_(d-1), two partitions having a size of N_(d-1)x2N_(d-1), four partitions having a size of N_(d-1)xN_(d-1) among partition types 992 to 998 to search for a partition type having a minimal coding error.

[000211] Even when partition type 998 has the minimum encoding error, as a maximum depth is d, an encoding unit CU_(d-1) having a depth of d-1 is no longer split to a lower depth , and an encoded depth for the encoding units constituting a current maximum encoding unit 900 is determined to be d-1 and a partition type of the current maximum encoding unit 900 can be determined to be N_(d-1)xN_( d-1). Also, as the maximum depth is d and a minimum encoding unit 980 having the lowest depth of d-1 is no longer split to a lower depth, the split information for the minimum encoding unit 980 is not established.

[000212] Data unit 999 can be a minimum unit for the current maximum encoding unit. A minimum unit according to an exemplary embodiment may be a rectangular data unit obtained by dividing a minimum encoding unit 980 by 4. By performing the encoding repeatedly, the video encoding apparatus 100 may select a depth having the error of minimal coding by comparing the coding errors according to the depths of the coding unit 900 to determine an coded depth, and establishing a corresponding partition type and prediction mode as a coding depth coding mode.

[000213] As such, the minimum encoding errors according to depths are compared across all depths from 1 to d, and the depth having the smallest encoding error can be determined as an encoded depth. The encoded depth, the prediction unit partition type, and the prediction mode can be encoded and transmitted as information about an encoding mode. Also, as an encoding unit is divided from a depth of 0 to an encoded depth, only the divided information of the encoded depth is set to 0, and the divided information of the depths excluding the encoded depth is set to 1.

[000214] The encoding information and picture data extractor 220 of the video decoding equipment 200 can extract and use the encoded depth information and the prediction unit of the encoding unit 900 to decode the partition 912. Video decoding 200 can determine a depth, at which the divided information is 0, as an encoded depth using the information divided according to the depths, and use the information about a corresponding depth encoding mode for decoding.

[000215] Figures 18, 19 and 20 are diagrams for depicting a relationship between encoding units 1010, prediction units 1060, and transforming units 1070, according to an exemplary embodiment.

[000216] Encoding units 1010 are encoding units that have a tree structure, corresponding to the encoded depths determined by the video encoding equipment 100, in a maximum encoding unit. The prediction units 1060 are partitions of the prediction units of each of the encoding units 1010, and the transform units 1070 are transformation units of each of the encoding units 1010.

[000217] When a maximum encoding unit depth is 0 at encoding units 1010, encoding units depths 1012 and 1054 are 1, encoding units depths 1014, 1016, 1018, 1028, 1050, and 1052 are 2, the depths of decoding units 1020, 1022, 1024, 1026, 1030, 1032 and 1048 are 3, and the depths of encoding units 1040, 1042, 1044 and 1046 are 4.

[000218] In the prediction units 1060, some encoding units 1014, 1016, 1022, 1032, 1048, 1050, 1052, 1054 are obtained by dividing the encoding units into the encoding units 1010. In other words, partition types in the encoding units 1014, 1022, 1050, and 1054 have a size of 2NxN, the partition types in encoding units 1016, 1048, and 1052 have a size of Nx2N, and a partition type of encoding unit 1032 has a size of NxN The prediction units and partitions of encoding units 1010 are less than or equal to each encoding unit.

[000219] Transformation or inverse transformation is performed on the image data of encoding unit 1052 in transforming units 1070 into a data unit that is smaller than encoding unit 1052. Furthermore, encoding units 1014, 1016, 1022, 1032, 1048, 1050 and 1052 in transforming units 1070 are different from those in prediction units 1060 in terms of sizes and shapes. In other words, video encoding and decoding apparatus 100 and 200 can perform intra prediction, motion estimation, motion compensation, transformation, and inverse transformation individually on a data unit in the same encoding unit.

[000220] Consequently, encoding is performed recursively on each of the encoding units having a hierarchical structure in each region of a maximum encoding unit to determine an optimal encoding unit, and thus encoding units having a structure of recursive tree can be obtained. The encoding information may include split information about an encoding unit, information about a partition type, information about a prediction mode, and information about a size of a transform unit. Table 1 shows the encoding information that can be set by video encoding and decoding equipment 100 and 200. Table 1

[000221] Output unit 130 of video encoding equipment 100 can output encoding information about encoding units having a tree structure, and extractor of encoding information and image data 220 of video decoding equipment 200 can extract encoding information about encoding units having a tree structure from a received bit stream.

[000222] Split information indicates whether a current encoding unit is divided into encoding units of a lower depth. If the information split from a current depth d is 0, a depth, at which a current encoding unit is no longer split at a lower depth, is an encoded depth, and so information about a partition type, the prediction mode , and a size of one transform unit, can be set to the encoded depth. If the current encoding unit is further divided according to the divided information, encoding is performed independently on four divided encoding units of a lower depth.

[000223] A prediction mode can be one of: an intra mode, an inter mode, and a jump mode. Intra mode and inter mode can be set on all partition types, and jump mode is only set on a partition type having a size of 2Nx2N.

[000224] Partition type information may indicate symmetric partition types having sizes of 2Nx2N, 2NxN, Nx2N, and NxN, which are obtained by symmetrically dividing a height or width of a prediction unit, and asymmetric partition types having sizes of 2NxnU, 2NxnD, nLx2N and nRx2N, which are obtained by dividing asymmetrically the height or width of the prediction unit. Asymmetric partition types having sizes of 2NxnU and 2NxnD can be obtained respectively by dividing the height of the prediction unit into 1:3 and 3:1, and asymmetric partition types having sizes of nLx2N and nRx2N can be obtained respectively by dividing the width of the prediction unit into 1:3 and 3:1.

[000225] The size of the transformation unit can be set to be two types in intra mode and two types in inter mode. In other words, if the transform unit information divided is 0, the transform unit size can be 2Nx2N, which is the current encoding unit size. If the transform unit divided information is 1, the transform units can be obtained by dividing the current encoding unit. Also, if a division type of the current encoding unit having the size of 2Nx2N is an asymmetric partition type, a size of a transform unit can be NxN, and if the partition type of the current encoding unit is a type of asymmetric partition, the size of the transformation unit can be N/2xN/2.

[000226] Encoding information about encoding units having a tree structure may include at least one of an encoding unit corresponding to an encoded depth, a prediction unit, and a minimum unit. The encoding unit corresponding to the encoded depth may include at least one of a prediction unit and a minimum unit containing the same encoding information.

[000227] It is accordingly determined whether the adjacent data units are included in the same encoding unit corresponding to the encoded depth by comparing the encoding information of the adjacent data units. Furthermore, a corresponding encoding unit corresponding to an encoded depth is determined using encoding information from a data unit, and thus a distribution of the encoded depths in a maximum encoding unit can be determined.

[000228] Consequently, if a current encoding unit is predicted based on encoding information from adjacent data units, encoding information from data units in deeper encoding units adjacent to the current encoding unit can be directly queried and used .

[000229] Alternatively, if a current encoding unit is predicted based on the encoding information from adjacent data units, the data units adjacent to the current encoding unit are searched using the encoding information from the data units, and adjacent coding units searched can be referred to for prediction of the current coding unit.

[000230] Figure 21 is a diagram for describing a relationship between an encoding unit, a prediction unit or a partition, and a transform unit, according to the encoding mode information of Table 1.

[000231] Maximum coding unit 1300 includes coding units 1302, 1304, 1306, 1312, 1314, 1316 and 1318 of coded depths. Here, as the encoding unit 1318 is an encoding unit of an encoded depth, the divided information can be set to 0. The information about a partition type of the encoding unit 1318 having a size of 2Nx2N can be set to be a of: a partition type 1322 having a size of 2Nx2N, a partition type 1324 having a size of 2NxN, a partition type 1326 having a size of Nx2N, a partition type 328 having a size of NxN, a partition type 1332 having a size of 2NxnU, a partition type 1334 having a size of 2NxnD, a partition type 1336 having a size of nLx2N, and a partition type 1338 having a size of nRx2N.

[000232] Division information (TU size indicator) of a transformation unit is a type of a transformation index, and a current size of a transformation unit can be determined based on the transformation index and a unit type of prediction or a partition type of a current encoding unit.

[000233] For example, when the partition type is set to be symmetric, that is, partition type 1322, 1324, 1326, or 1328, a transform unit 1342 having a size of 2Nx2N is established if split information (split indicator TU size) of a transform unit is 0, and a transform unit 1344 having a size of NxN is established if a TU size indicator is 1.

[000234] On the other hand, when the partition type is established to be asymmetric, that is, partition type 1332, 1334, 1336 or 1338, a transform unit 1352 having a size of 2Nx2N is established if a size indicator TU is 0, and a transform unit 1354 having a size of N/2xN/2 is established if a TU size indicator is 1.

[000235] Consequently, the size of the transformation unit corresponding to the transformation index can vary according to a type of prediction unit or a type of partition of an encoding unit.

[000236] Referring to Figure 21, the TU size indicator is an indicator having a value of 0 or 1, however the TU size indicator is not limited to 1 bit, and the transformation unit can be divided hierarchically having a tree structure while the TU size indicator increases from 0.

[000237] In this case, the size of a transformation unit that was actually used can be expressed using a TU size indicator of a transformation unit, according to an exemplary modality, together with a maximum size and a size minimum of the processing unit. According to an exemplary embodiment, the video encoding apparatus 100 is capable of encoding maximum transform unit size information, minimum transform unit size information, and a maximum TU size indicator. The result of encoding the maximum transform unit size information, minimum transform unit size information, and the maximum TU size indicator can be entered into an SPS. According to an exemplary embodiment, the video encoding apparatus 200 can decode video using the maximum transform unit size information, the minimum transform unit size information, and the maximum TU size indicator.

[000238] For example, if the size of a current encoding unit is 64x64 and a maximum transform unit size is 32x32, then the size of a transform unit can be 32x32 when a TU size indicator is 0, it can be 16x16 when the TU size indicator is 1, and can be 8x8 when the TU size indicator is 2.

[000239] As another example, if the current encoding unit size is 32x32 and a minimum transform unit size is 32x32, then the transform unit size can be 32x32 when the TU size indicator is 0. Here, the TU size indicator cannot be set to a value other than 0, since the size of the transform unit cannot be smaller than 32x32.

[000240] As another example, if the current encoding unit size is 64x64 and a maximum TU size indicator is 1, then the TU size indicator can be 0 or 1. Here, the TU size indicator cannot be adjusted to a value other than 0 or 1.

[000241] So, if the maximum TU size indicator is set to "MaxTransformSizeIndex", a minimum transform unit size is "MinTransformSize", and a transform unit size is "RootTuSize" when the TU size indicator is 0, then a current minimum transform unit size "CurrMinTuSize" which can be determined in a current encoding unit, can be set by Equation (1): Equation 1 CurrMinTuSize=max(MinTransformSize,RootTuSize/(2^MaxTransformSizeIndex))

[000242] Compared to the current minimum transform unit size "CurrMinTuSize" which can be determined in the current encoding unit, a transform unit size "RootTuSize" when the TU size indicator is 0, can denote a size of Maximum transformation unit that can be selected in the system. In Equation (1), "RootTuSize(2AMaxTransformSizeIndex)" denotes a transform unit size when the transform unit size "RootTuSize", when the TU size indicator is 0 it is divided by the number of times corresponding to the size indicator Maximum TU, and "MintransformSize" denotes a minimum transformation size. So, a smaller value between "RootTuSize/(2AMaxTransformSizeIndex)" and "MinTransformSize" can be the current minimum transform unit size "CurrMinTuSize" which can be determined in the current encoding unit.

[000243] According to an exemplary embodiment, the maximum RootTuSize transform unit size may vary according to the type of prediction mode.

[000244] For example, if a current prediction mode is an inter mode, then RootTuSize can be determined using Equation (2) below. In Equation (2), "MaxTransformSize" denotes a maximum transform unit size, and "PUSize" denotes a current prediction unit size. Equation 2 RootTuSize = min(MaxTransformSize, PUSize)

[000245] That is, if the current prediction mode is inter mode, the transform unit size "RootTuSize" when the TU size indicator is 0, can be a smaller value between the maximum transform unit size and the current prediction unit size.

[000246] If a prediction mode of a current partition unit is an intra mode, "RootTuSize" can be determined using Equation (3) below. In Equation (3), "PartitionSize" denotes the size of the current partition drive. Equation 3 RootTuSize = min(MaxTransformSize, PartitionSize)

[000247] That is, if the current prediction mode is intra mode, the transform unit size "RootTuSize" when the TU size indicator is 0 can be a smaller value between the maximum transform unit size and the size of the current partition drive.

[000248] However, the current maximum transform unit size "RootTuSize" which varies according to the type of a prediction mode in a partition unit is just an example and is not limited to that.

[000249] According to an exemplary embodiment, the size of the current maximum transformation unit 'RootTuSize' can be equal to the size of the current encoding unit. According to another exemplary embodiment, the size of the current maximum transformation unit 'RootTuSize' can be determined based on a prediction unit type or a partition type of the current prediction unit or partition. For example, the current maximum transform unit size 'RootTuSize' can indicate the size of a maximum frame included in the current prediction unit or partition.

[000250] Figure 22 is a flowchart illustrating a video encoding method using a transform index based on encoding units and transforming units having a tree structure, according to an exemplary embodiment.

[000251] In operation 1210, a current frame is divided into at least one maximum encoding unit. A maximum depth indicating the total number of possible division times can be predetermined.

[000252] In operation 1220, an encoded depth to produce a final encoding result according to at least one divided region, which is obtained by dividing a region of each maximum encoding unit according to depths, is determined by encoding at least one divided region is given, and an encoding unit according to a tree structure is determined.

[000253] The maximum encoding unit is spatially divided whenever the depth is deepened, and thus is divided into encoding units of a lower depth. Each encoding unit can be divided into encoding units of another lower depth by virtue of being spatially divided independently from adjacent encoding units. Encoding is performed repeatedly on each encoding unit according to depths.

[000254] Also, a transformation unit according to partition types having the minimum encoding error is determined for each deeper encoding unit. To determine an encoded depth having a minimum encoding error in each maximum encoding unit, encoding errors can be measured and compared in all deeper encoding units according to depths.

[000255] In determining the encoding unit, transformation units, being a data unit into which the communication unit is transformed, can be determined. The transformation units can be determined to be a data unit minimizing an error due to transformation in the encoding unit. Transform units can be determined to be the same size within a single encoding unit. As a result of performing transformation at each level according to a transformation depth within a current encoding unit, transformation units based on a tree structure form a hierarchical structure between transformation units in the same region according to with the transformation depths are independent of the transformation units in the other region, can be determined.

[000256] In operation 1230, encoded image data constituting the final encoding result according to the encoded depth is output for each maximum encoding unit, with encoding information about the encoded depth and an encoding mode. The encoding mode information may include information about an encoded depth or split information, information about a partition type of a prediction unit, a prediction mode, and a size of a transform unit. The encoded information about the encoding mode can be transmitted to a decoder with the encoded image data.

[000257] Figure 23 is a flowchart illustrating a video decoding method that uses a transformation index based on encoding units and transformation units having a tree structure, according to an exemplary embodiment.

[000258] In operation 1310, an encoded video bit stream is received and analyzed.

[000259] In operation 1320, the encoded image data of a current frame assigned to a maximum encoding unit, and information about an encoded depth and an encoding mode according to the maximum encoding units are extracted from the video stream. bits analyzed. The encoded depth of each maximum encoding unit is a depth that has the minimum encoding error in each maximum encoding unit. In encoding each maximum encoding unit, the image data is encoded based on at least one data unit obtained by hierarchically dividing each maximum encoding unit according to depths.

[000260] According to the information indicating the encoded depth and encoding mode, the maximum encoding unit can be divided into encoding units having a tree structure. Each of the encoding units having the tree structure is determined as an encoding unit corresponding to an encoded depth, and is optimally encoded so as to produce the minimum encoding error. Accordingly, the efficiency of encoding and decoding an image can be improved by decoding each fraction of image data encoded in the encoding units after determining at least an encoded depth according to the encoding units.

[000261] According to the transform index included in the encoding mode information, transform units having a tree structure within an encoding unit can be determined. For example, the number of divisions from the current encoding unit to a transform unit can be read from the transform index. In another embodiment, it can be determined whether the current encoding unit is divided into lower-level transform units, and thus a structure of transform units having a tree structure can finally be read from a sequence of bits that indicates whether the division from the highest transform unit to a lower transform unit is performed for each region of the current encoding unit.

[000262] In operation 1330, the image data of each maximum encoding unit is decoded based on the information about the encoded depth and the encoding mode according to the maximum encoding units. The decoded image data can be played back by playback equipment, stored on a storage medium, or transmitted over a network.

[000263] Exemplary modalities may be recorded with computer programs and may be implemented on commonly used digital computers that run the programs using a computer-readable recording medium. Examples of computer readable recording media include magnetic storage media (eg ROM, floppy disks, hard disks, etc.) and optical recording media (eg CD-ROMs or DVDs). Alternatively, exemplary embodiments may be embodied as computer readable transmission media, such as data signals, for transmission over a computer network, for example, the Internet.

[000264] The video encoding equipment or video decoding equipment of the exemplary modalities may include a bus coupled to each unit of the equipment, at least one processor connected to the bus that executes commands, and a memory connected to the bus that stores the commands , messages received and messages generated.

[000265] While this invention has been shown and described particularly with reference to its exemplary embodiments, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined. by the attached claims. Exemplary modalities should be considered only in the descriptive sense and not for the purpose of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention, but by the appended claims, and all differences within the scope will be deemed to be included in the present invention.

Claims (4)

1. METHOD TO DECODE AN ENCODED VIDEO, characterized by the fact that it comprises: receiving a bit stream of an encoded video; determining at least one encoding unit using division information extracted from the bit stream; extracting from the bitstream transform index information indicating whether a transform unit of a current level included in an encoding unit among the at least one encoding unit is divided; when the transformation index information indicates a division of the transformation unit of the current level, dividing the transformation unit of the current level into transformation units of a lower level; and when the transformation index information indicates a non-division of the transformation unit of the current level, perform an inverse transformation on the transformation unit of the current level to generate residual data corresponding to the transformation unit of the current level, where the transformation unit of the current level is divided into four lower level transformation units. 2. Method for decoding video, according to claim 1, characterized in that the current level transform unit is included in the encoding unit and a current level transform unit size is less than or equal to a current level transform unit size. encoding unit. 3. Method for decoding video, according to claim 2, characterized in that the current level transformation unit is obtained by dividing a height and a width of the encoding unit in half. 4. Method for decoding video, according to claim 1, characterized in that the encoding unit is a data unit in which an encoded video image is encoded and the current level transformation unit is a data unit into which the encoding unit data is transformed.

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