KR102028127B1 - Method and apparatus for video encoding based on prediction using variable partition, and method and apparatus for video decoding based on prediction using variable partition - Google Patents

Abstract

According to an embodiment of the present invention, a first partition mode indicating a shape and a direction of a partition, which is a data unit for predictive encoding of a coding unit, for each coding unit that is a data unit for encoding a picture, and the coding unit is used as a partition for detailed motion prediction. Predictive encoding is performed using partitions determined based on the partition level indicating the degree of partitioning, thereby determining a partition to output the encoding result, and encoding and outputting partition information indicating the first partition mode and partition level of the partition. Disclosed is a video encoding method using a variable partition.

Description

Method and apparatus for video encoding using variable partition for predictive encoding, and method and apparatus for video encoding based on prediction using variable partition, and method and apparatus for video decoding based on prediction using variable partition}

The present invention relates to the encoding and decoding of video.

With the development and dissemination of hardware capable of playing and storing high resolution or high definition video content, there is an increasing need for a video codec for efficiently encoding or decoding high resolution or high definition video content. According to the existing video codec, video is encoded according to a limited encoding method based on a macroblock of a predetermined size.

Video compression greatly exploits spatial and temporal correlations. In general, inter prediction is performed based on a specific size, for example, a 16x16 macroblock. In the inter prediction, when the macroblock of the specific size is divided into two, four, or more regions, and inter prediction is performed on each motion region, distortion of the reconstructed image is generated, compared to the original image. Overhead for transmitting the inter prediction result may occur. If the motion region for inter prediction is finely divided, the distortion of the reconstructed image is reduced but the overhead is increased compared to the original image. Therefore, a trade-off relationship may be formed between the distortion and the overhead of the reconstructed image compared to the original image in inter prediction.

The present invention relates to video encoding and video decoding using partitions of variable shape and size for predictive encoding.

In a video encoding method using a variable partition for predictive encoding according to an embodiment of the present invention, for each coding unit that is a data unit for encoding a picture, the shape and directionality of the partition that is a data unit for predictive encoding of the coding unit Determine a partition to output an encoding result by performing prediction encoding using partitions determined based on a partition mode indicating a partitioning degree in which the coding unit is divided into partitions for detailed motion prediction. Making; And encoding and outputting partition information indicating a first partition mode and a partition level of the determined partition.

In a video decoding method using a variable partition for predictive encoding according to an embodiment of the present invention, data for predictive encoding of the coding unit, for each coding unit that is a data unit for encoding a picture, from a received bitstream Extracting partition information including a first partition mode indicating a form and direction of a partition as a unit and a partition level indicating a degree in which the coding unit is divided into partitions for detailed motion prediction; And decoding the picture by performing predictive decoding using partitions determined based on the first partition mode and the partition level of the extracted partition information.

In a video encoding apparatus using a variable partition for predictive encoding according to an embodiment of the present invention, the shape and directionality of a partition that is a data unit for predictive encoding of the coding unit for each coding unit that is a data unit for encoding a picture Determine a partition to output an encoding result by performing prediction encoding using partitions determined based on a partition mode indicating a partitioning degree in which the coding unit is divided into partitions for detailed motion prediction. An encoder configured to encode the picture to determine an encoding mode of the coding unit; And encoding information including partition information indicating a first partition mode and a partition level of the determined partition, information about a prediction mode of the partition, and information about the encoding mode, and predictively encoding the partition by using the determined partition. And an output unit for encoding and outputting the motion vector and the residual of the partition.

According to an embodiment of the present invention, a video decoding apparatus using a variable partition for predictive encoding includes data for predictive encoding of the coding unit, for each coding unit that is a data unit for encoding a picture from the received bitstream. Partition information including a first partition mode indicating a shape and a direction of a partition which is a unit, a partition level indicating a degree to which the coding unit is divided into partitions for detailed motion prediction, information on a prediction mode of the partition, and An extraction unit for extracting encoding information including information about an encoding mode, a motion vector, and a residual of the partition; And decoding to perform prediction decoding on the partitions and to decode the picture based on the encoding mode based on the first partition mode of the extracted partition information and the prediction mode of partitions determined based on the partition level. Contains wealth.

The present invention includes a computer-readable recording medium having recorded thereon a program for implementing a video encoding method using a variable partition for predictive encoding according to an embodiment.

The present invention includes a computer-readable recording medium having recorded thereon a program for implementing a video decoding method using a variable partition for predictive encoding according to an embodiment.

1 is a block diagram of a video encoding apparatus using a variable partition according to an embodiment of the present invention.
2 is a block diagram of a video decoding apparatus using a variable partition according to an embodiment of the present invention.
3 illustrates coding units of a hierarchical structure, according to an embodiment.
4 illustrates partitions of a tree structure defined by a first partition mode and a partition level, according to an embodiment.
5 illustrates a relationship between a first partition mode, a partition level, and a second partition mode according to an embodiment.
6 is a flowchart of a video encoding method using a variable partition according to an embodiment of the present invention.
7 is a flowchart of a video decoding method using a variable partition according to an embodiment of the present invention.
8 is a block diagram of a video decoding apparatus using a variable partition based on coding units having a tree structure, according to an embodiment of the present invention.
9 is a block diagram of a video decoding apparatus using a variable partition based on coding units having a tree structure, according to an embodiment of the present invention.
10 illustrates a concept of coding units, according to an embodiment of the present invention.
11 is a block diagram of an image encoder based on coding units, according to an embodiment of the present invention.
12 is a block diagram of an image decoder based on coding units, according to an embodiment of the present invention.
13 is a diagram of deeper coding units according to depths, and partitions, according to an embodiment of the present invention.
14 illustrates a relationship between a coding unit and transformation units, according to an embodiment of the present invention.
FIG. 15 illustrates encoding information according to depths, according to an embodiment of the present invention.
16 is a diagram of deeper coding units according to depths, according to an embodiment of the present invention.
17, 18, and 19 illustrate a relationship between a coding unit, a prediction unit, and a transformation unit, according to an embodiment of the present invention.
20 illustrates a relationship between a coding unit, a prediction unit, and a transformation unit, according to encoding mode information of Table 1. FIG.
21 is a flowchart of a video encoding method using a variable partition based on a coding unit having a tree structure, according to an embodiment.
22 is a flowchart of a video decoding method using variable partitions based on coding units having a tree structure, according to an embodiment of the present invention.

In various embodiments of the present invention described herein below, the term 'image' may refer to a generic image including a still image as well as a video such as a video. Hereinafter, in various embodiments of the present disclosure described herein, the 'data unit' refers to a set of data of a predetermined range of data constituting the video.

Hereinafter, referring to FIGS. 1 to 7, encoding and decoding of a video using a variable partition for predictive encoding according to an embodiment are disclosed. Hereinafter, video encoding and decoding using variable partitions for predictive encoding are disclosed based on coding units having a tree structure according to an embodiment of the present invention with reference to FIGS. 8 to 22.

1 is a block diagram of a video encoding apparatus using a variable partition for predictive encoding according to an embodiment of the present invention.

The video encoding apparatus 10 using the variable partition according to an embodiment includes an encoder 11 and an output unit 12. For convenience of description, a video encoding apparatus 10 using a variable partition according to an embodiment will be referred to as a video encoding apparatus 10.

The video encoding apparatus 10 according to an embodiment receives an image sequence of a video, encodes the encoded video data by performing inter-picture inter prediction, intra picture intra prediction, transformation, quantization, and entropy encoding for each picture Encoding information including information about an encoding mode is output.

The encoding apparatus 10 according to an embodiment may divide a picture into data units having a predetermined size and encode each picture unit for efficient encoding of the picture. Hereinafter, a data unit for encoding a picture is referred to as a 'coding unit'. The encoder 11 according to an embodiment may determine a coding unit and determine a coding scheme to be performed for each coding unit. At this time, the encoding method determined for each coding unit is an encoding mode.

Data can overlap between temporally successive sequences of video or spatially surrounding areas. In the video compression encoding scheme, a prediction encoding technique for encoding with reference to spatiotemporal peripheral data is performed to reduce the size of encoded data by removing redundant data between adjacent data in space and time.

In the predictive encoding scheme, neighboring data overlapping each other is searched based on data units having a predetermined size and shape, and a difference value between the overlapping data units (ie, motion) and the original data and the overlapping data ( That is, residual may be encoded.

The encoder 11 according to an embodiment may determine a partition, which is a data unit for comparing a movement with surrounding data for prediction encoding, for each coding unit. The size of the partition may be equal to or smaller than the coding unit. The encoder 11 according to an embodiment may output residuals from which data overlapped for each partition is removed according to predictive encoding using the determined partition.

The encoder 11 according to an embodiment performs prediction encoding on partitions determined based on the first partition mode and the partition level to determine a partition to output an encoding result.

The encoder 11 according to an embodiment may perform prediction encoding using partitions having various shapes, directions, and sizes for each coding unit, and may determine a partition to finally output residual among the partitions. The encoder 11 according to an embodiment may select a partition having the highest encoding efficiency by determining and comparing encoding efficiency according to predictive encoding for each of the various partitions.

The encoding efficiency may be determined in consideration of an error between the original data and the reconstructed data, an overhead occurring after the encoding, and the like. For example, the coding efficiency according to the predictive coding may be measured using a Lagrangian multiplier based rate-distortion optimization technique.

Partitions according to an embodiment may be defined based on the first partition mode and the partition level. The first partition mode according to an embodiment represents the shape and the orientation of the partition.

For example, a partition type such as a partition such as a rectangular partition, a square partition, a non-square partition, or the like may be defined according to the first partition mode. For example, partitions divided into vertical, horizontal, vertical and horizontal directions, and diagonal directions of the coding unit according to the first partition mode; A partition partitioned to the left, right, top, or bottom of the coding unit; Partitions in which adjacent widths and opposite heights of coding units are divided into adjacent widths and heights; Orientation in which coding units such as such are divided into partitions may be defined.

The partition level according to an embodiment represents the degree to which a coding unit is divided into partitions for detailed motion prediction. In addition, the ratio of the width (height) of the partition to the width (height) of the coding unit may be determined according to the partition level.

For example, as the partition level increases according to an embodiment, a partition having a finely divided width and height of a coding unit may be determined. For example, based on a size in which the width or height of the coding unit is divided into n, the width or height of the coding unit is 1: (n-1), 2: (n-2), ..., (n-2 Partitions partitioned in a ratio of: 2, (n-1): 1 can be determined. In this case, n may increase as the partition level increases.

However, the minimum size of a partition according to an embodiment is limited and coding units may not be infinitely divided. Accordingly, at least one of an upper limit and a lower limit of a partition level of a partition may be determined based on the size of a current coding unit whose size is determined according to a hierarchical tree structure. In addition, partition levels may be limited by system or user settings.

Also, among partitions whose shape and direction are determined based on the first partition mode, the width and height of the partitions may increase or decrease. Widths and heights of partitions whose shapes and directions are determined based on the first partition mode may be defined according to the second partition mode. That is, the second partition mode may determine a detailed partition type among the allowable partitions according to the first partition mode.

In addition, the partitions of the first partition mode, the shape and orientation of the partition is determined according to the first partition mode, and at least one of the width and height of the partition increases or decreases to a multiple of the minimum width or the minimum height of the partition determined according to the partition level The second partition mode may be defined to point to each of the partitions of the first partition mode.

For example, when the minimum width and minimum height of the partition are determined as n equal values of the width and height of the coding unit according to the partition level, the second partition mode has a width or height of 1: (n-1), It represents each partition divided by the ratio of 2: (n-2), ..., (n-2): 2, (n-1): 1.

Accordingly, the encoder 11 according to an embodiment may further determine the second partition mode according to the first partition mode, and the type or number of the second partition modes may be determined according to the first partition mode and the partition level. .

The output unit 12 according to an embodiment may encode and output partition information indicating a first partition mode and a partition level of a partition determined by the encoder 11. The partition information may further include second partition mode information according to the first partition mode. The partition information according to an embodiment may include partition level restriction information that determines a lower limit or an upper limit of a partition level.

The output unit 12 according to an embodiment may output the motion vector and the residual of the partition generated by predictive encoding using the partition determined by the encoder 11. In addition, the output unit 12 according to an embodiment encodes encoding information including information about an encoding mode together with information about a prediction mode indicating a prediction encoding method using a partition determined by the encoding unit 11. Can be output. Encoding information according to an embodiment may be inserted into a sequence parameter set (SPS). Encoding information according to an embodiment may be encoded and inserted for each data unit such as a sequence, a picture, a frame, a slice, and a maximum coding unit.

2 is a block diagram of a video decoding apparatus using a variable partition for predictive encoding according to an embodiment of the present invention.

The video decoding apparatus 20 using a variable partition for predictive encoding according to an embodiment includes an extractor 21 and a decoder 22. Hereinafter, a video decoding apparatus 20 using a variable partition for predictive encoding according to an embodiment for convenience of description will be referred to as a video decoding apparatus 20 according to an embodiment.

The video decoding apparatus 20 according to an embodiment receives a bitstream in which a picture sequence of a video is encoded, entropy decoding, inverse quantization, inverse transformation, inter picture inter prediction / compensation, intra intra picture, and the like for encoded picture data. The picture is reconstructed through decoding.

The extractor 21 according to an embodiment may parse the received bitstream to extract encoded picture data and a motion vector. According to an embodiment, the extractor 21 may extract the encoded residual by parsing the received bitstream.

The extractor 21 according to an embodiment parses the received bitstream to extract encoding information. The extractor 21 according to an embodiment may read information about an encoding mode, partition information, and a prediction mode from among encoding information. From partition information according to an embodiment, a first partition mode and a partition level of a partition of a coding unit may be read.

The partition information extracted by the extractor 21 according to an embodiment may include a first partition mode and a partition level having the highest coding efficiency among partitions of a hierarchical tree structure configured according to the first partition mode and the partition level. It may include.

The decoder 22 according to an embodiment may determine a partition for predictive decoding of a picture based on the partition information extracted and read by the extractor 21. In addition, the decoder 22 according to an exemplary embodiment may predictively decode a residual of a partition by using the prediction mode and the motion vector extracted by the extractor 21.

The decoder 22 according to an embodiment may determine a partition based on partition information for each coding unit. The decoder 22 according to an embodiment may determine the partition type and the directionality of splitting the coding unit into partitions based on the first partition mode among the partition information. In addition, the decoder 22 according to an embodiment may determine the degree to which the coding unit is densely divided into partitions based on the partition level in the partition information.

For example, the decoder 22 according to an embodiment may determine a partition type of a rectangular partition, a square partition, a non-rectangular partition, or the like based on the first partition mode. The decoder 22 according to an embodiment may determine the direction in which the coding unit is divided into partitions based on the first partition mode. For example, a partition according to the first partition mode may include partitions divided into vertical, horizontal, vertical and horizontal directions, and diagonal directions of a coding unit; A partition partitioned to the left, right, top, or bottom of the coding unit; Partitions in which adjacent widths and opposite heights of coding units are divided into adjacent widths and heights; And the like.

The decoder 22 according to an embodiment may determine a ratio of dividing the width and height of the coding unit based on the partition level. As the partition level increases, a partition in which the width and the height of the coding unit are finely divided may be determined. For example, at least one of the width and height of the coding unit is 1: (n-1), 2: (n-2), ..., (n-2): 2, (n-1): 1 When partitions partitioned by a ratio are determined, n may increase as the partition level increases.

An upper limit or a lower limit of a partition level of a partition may be determined based on the size of a current coding unit whose size is determined according to a hierarchical tree structure. In addition, a partition level may be extracted from a bitstream in which information on a limit value is received according to a system or user setting.

The extractor 21 according to an embodiment may further extract, from the partition information, a second partition mode indicating a partition having a predetermined width and height among partitions whose shape and direction are determined based on the first partition mode. Accordingly, the decoder 22 according to an embodiment may determine partitions for each coding unit based on the first partition mode information, the partition level, and the second partition mode information of the partition information.

The decoder 22 according to an embodiment may increase or decrease the width and height of partitions whose shape and direction are determined based on the first partition mode based on the second partition mode.

In addition, the width and height of the partitions determined in the second partition mode is at least one of the width and height of the partition having the shape and orientation determined according to the first partition mode, the minimum width or the minimum height of the partition determined according to the partition level It may also be determined as a multiple of.

For example, the minimum width and the minimum height of the partition may be determined as n equal values of the width and the height of the coding unit according to the partition level. The decoder 22 according to an embodiment may have a width or a height of 1: (n-1), 2: (n-2), ..., (n-2) of a coding unit based on the second partition mode. You can determine each partition divided by the ratio :): 2, (n-1): 1.

The decoder 22 according to an embodiment may perform prediction decoding on partitions determined based on partition information based on a prediction mode, and decode a picture based on an encoding mode.

The video encoding apparatus 10 using the variable partition for the predictive encoding according to the embodiment and the video decoding apparatus 20 using the variable partition for the predictive encoding according to the embodiment are the same size as the existing macroblock. In addition to partitions, bipartite partitions, and quadrant partitions, you can decide which partitions can take into account the texture's orientation, position, and the partition's detailed movement. In addition, since the shape and direction of the partition capable of predicting the detailed movement of the partition can be adjusted based on the size of the coding unit, prediction encoding and decoding can be sufficiently performed in consideration of image characteristics.

3 illustrates coding units of a hierarchical structure, according to an embodiment.

According to the hierarchical structure 30 of coding units according to an embodiment, as coding unit levels increase to 0, 1, and 2, sizes of coding units 31, 32, and 33 may decrease. As the sizes of the coding units 31, 32, and 33 increase, texture components of various shapes and directions may be included in the coding unit, and different motion regions may be included in the coding unit according to the passage of time in the video sequence. Therefore, for more precise and accurate predictive coding of coding units, it is necessary to vary the shape, directionality, and size of partitions included in coding units based on the size of coding units.

4 illustrates partitions of a tree structure defined by a first partition mode and a partition level, according to an embodiment.

The tree structure 50 of a partition according to an embodiment may be composed of partitions defined by a first partition mode and a partition level. The encoder 11 of the video encoding apparatus 10 according to an embodiment performs prediction encoding on all of the partitions constituting the tree structure 50 for each coding unit, and then selects the partition having the highest encoding efficiency. In operation, the output unit 12 may encode and output the residual of the determined partition.

The first partition mode according to an embodiment may indicate a form and direction of a partition, and the partition level may indicate a degree in which a coding unit is divided into partitions for detailed motion prediction. The partition may be defined according to a combination of the first partition mode and the partition level.

Partition group 49 of partition level 0 includes partition set 40 of first partition mode 0, partition set 41 of first partition mode 1, partition set 42 of first partition mode 2, and first partition Partition set 43 of mode 3, partition set 44 of first partition mode 4, partition set 45 of first partition mode 5, partition set 46 of first partition mode 6, first partition mode 7 Partition set 47.

The partition set 40 of the first partition mode 0 of partition level 0 includes a partition (index 0) having the same size as the coding unit.

In addition, the partition set 41 of the first partition mode 1 of partition level 0 divides the heights of the coding units facing each other by 1/2, so that the rectangular partitions (index 0 and 1) whose coding units are divided in the horizontal direction are divided into 1/2. It may include. In addition, the partition set 42 of the first partition mode 2 of partition level 0 divides the opposite widths of the coding units into 1/2, so that the rectangular partitions (index 0 and 1) whose coding units are divided in the vertical direction are divided into 1/2. It may include.

The partition set 43 of the first partition mode 3 of the partition level 0 is divided into two half of each of the opposite height and the opposite width of the coding unit so that the coding unit is divided into four horizontal and vertical directions. Indexes 0, 1, 2, and 3).

The partition set 44 of the first partition mode 4 of the partition level 0 includes a rectangular partition (index 0) having a size that is located at the top left of the coding unit and is divided into 1/2 each of the left height and the top width of the coding unit. The remaining pieces may contain non-rectangular partitions (index 1).

The partition set 45 of the first partition mode 5 of the partition level 0 includes a rectangular partition (index 1) having a size that is located at the upper right side of the coding unit and is divided into 1/2 each of the right height and the top width of the coding unit. The rest of the fragments may contain non-rectangular partitions (index 0).

The partition set 46 of the first partition mode 6 of the partition level 0 includes a rectangular partition (index 0) having a size that is located at the lower left of the coding unit and the left height and the bottom width of the coding unit are divided into 1/2 each. The remaining pieces may contain non-rectangular partitions (index 1).

The partition set 47 of the first partition mode 7 of partition level 0 includes a rectangular partition (index 1) having a size that is located at the lower right side of the coding unit and is divided into 1/2 each of the right height and the bottom width of the coding unit. The rest of the fragments may contain non-rectangular partitions (index 0).

The first partition modes 1 and 2 may define partitions for accurate prediction encoding when motion is different between upper and lower regions or between left and right regions in a coding unit. The first partition mode 3 may define a partition for detailed prediction encoding for each partition when a plurality of objects or a plurality of regions exist in a coding unit and have a complex motion.

In the first partition modes 4, 5, 6, and 7, when a diagonal edge is located in a coding unit, a partition for accurate prediction encoding of regions partitioned by an edge may be defined. However, when the first partition modes 3, 4, 5, 6, and 7 are used, since accurate motion prediction is possible but overhead increases, it is preferable to be used in consideration of a tradeoff between coding efficiency and overhead.

The partition level represents the degree to which the coding unit is densely divided into partitions for fine motion prediction. As the partition level increases, the minimum height or the minimum width of the partition may decrease.

In the tree structure 50 of a partition according to an embodiment, the minimum width (minimum height) of the partition unit is a size obtained by dividing the width (height) of the coding unit by the square of two, and as the partition level increases, the square of two is increased. Increases.

As described above, when the partition level is 0, the height (width) of the coding unit is not divided or is divided into 1/2. When the partition level is increased to 1, the minimum height (minimum width) of the partition may be 1/4 of the height (width) of the coding unit. When the partition level is increased to 2, the minimum height (minimum width) of the partition may be 1/8 of the height or width of the coding unit.

Regardless of the partition level, the size of the coding unit is the same. Partition group 59 of partition level 1 has two times the precision compared to partition level zero. According to an embodiment, in partition level 0, the first partition mode 1 is a partition in which the height of the encoding size is subdivided to a precision of 1/2, and in partition level 1, the first partition mode 1 is a precision in which the height of the encoding size is 1/4. Partition is subdivided into Furthermore, in partition level 2, the first partition mode 1 is a partition having a height of an encoding size of 1/8.

In one first partition mode, partitions of the same type may occur redundantly between partition levels. For example, in the first partition modes 3, 4, 5, 6 and 7, partition sets 43, 44, 45, 46 and 47 at partition level 0 are partition sets 53e, 54e, 55e and 56e at partition level 1, respectively. , 57e is the same form. In the first partition modes 1 and 2, partition sets 51a and 51b of partition level 1 are the same as partition sets 61b and 61e of partition level 2, and partition sets 52a and 52b of partition level 1 are partitions of partition level 2, respectively. It is the same form as the set 62b, 62e.

When partitions determined based on the same first partition mode and different partition levels have the same shape, only partitions of a lower partition level may be used for predictive encoding. For example, in first partition mode 3, partition set 53e at partition level 1 is the same as partition set 43 at partition level 0, so only partition set 43 of first partition mode 3 at lower partition level 0 is the actual prediction. Only partition information used for encoding and representing partition set 43 can be encoded. In this case, partition information for representing partition set 53e is not defined.

The partition sets 51a and 51b of the first partition mode 1 of the partition level 1 may include rectangular partitions (indexes 0 and 1) whose opposing heights of the coding unit are divided into 1: 3 and 3: 1, respectively. have. In addition, the partition sets 52a and 52b of the first partition mode 2 of the partition level 1 may include rectangular partitions (indexes 0 and 1) whose opposing widths of the coding unit are divided into 1: 3 and 3: 1, respectively. Can be.

The partition set 53a, 53b, 53c, 53d, 53e, 53f, 53g, 53h, 53i of the first partition mode 3 of partition level 1 may have at least one of the opposite height and the opposite width of the coding unit being 1: 3. , Divided into 2: 2, 3: 1, and quadrature partitions (indexes 0, 1, 2, and 3) in which a coding unit is divided into 4 horizontally and vertically directions may be defined. However, in the first partition mode 3, partition set 53e of partition level 1 overlaps partition set 43 of partition level 0 and thus may not be used for predictive encoding. In addition, at partition level 1, partition information indicating partition set 53e of first partition mode 3 may not be defined.

The partition sets 54a, 54b, 54c, 54d, 54e, 54f, 54g, 54h, and 54i of the first partition mode 4 of partition level 1 are located at the upper left of the coding unit, and among the left height and the top width of the coding unit. At least one may include a rectangular partition (index 0) having a size divided into 1: 3, 2: 2, and 3: 1 and a non-rectangular partition (index 1) of the remaining pieces. However, in the first partition mode 4, since partition set 54e of partition level 1 overlaps partition set 44 of partition level 0, it may not be used for predictive encoding. In addition, at partition level 1, partition information indicating partition set 54e of first partition mode 4 may not be defined.

The partition sets 55a, 55b, 55c, 55d, 55e, 55f, 55g, 55h, and 55i of the first partition mode 5 of partition level 1 are located at the upper right side of the coding unit, and among the right height and the top width of the coding unit. At least one may include a rectangular partition (index 1) having a size divided into 1: 3, 2: 2, and 3: 1, and a non-rectangular partition (index 0) of the remaining pieces. However, in the first partition mode 5, the partition set 55e of the partition level 1 is a partition overlapping with the partition set 45 of the partition level 0, and thus may not be used for predictive encoding. In addition, at partition level 1, partition information indicating partition set 55e of first partition mode 5 may not be defined.

The partition set 56a, 56b, 56c, 56d, 56e, 56f, 56g, 56h, 56i of the first partition mode 6 of partition level 1 is located at the lower left of the coding unit, and among the left height and the lower width of the coding unit. At least one may include a rectangular partition (index 0) having a size divided into 1: 3, 2: 2, and 3: 1, and a non-rectangular partition (index 1) of the remaining pieces. However, in the first partition mode 6, since the partition set 56e of the partition level 1 is a partition overlapping with the partition set 46 of the partition level 0, it may not be used for predictive encoding. In addition, at partition level 1, partition information indicating partition set 56e of first partition mode 6 may not be defined.

The partition sets 57a, 57b, 57c, 57d, 57e, 57f, 57g, 57h, and 57i of the first partition mode 7 of partition level 1 are located at the lower right of the coding unit, and among the right height and the lower width of the coding unit. At least one may include a rectangular partition (index 1) having a size divided into 1: 3, 2: 2, and 3: 1, and a non-rectangular partition (index 0) of the remaining pieces. However, in the first partition mode 7, since partition set 57e of partition level 1 is a partition overlapping with partition set 47 of partition level 0, it may not be used for predictive encoding. In addition, at partition level 1, partition information indicating partition set 57e of the first partition mode 7 may not be defined.

In a similar manner, the partition sets 61a, 61b, 61c, 61d, 61e, and 61f of the first partition mode 1 of partition level 2 have opposite heights of coding units 1: 7, 2: 6, 3: 5, respectively. And may include rectangular partitions (index 0, 1) divided into 5: 3, 6: 2, 7: 1. However, in the first partition mode 1, partition sets 61b and 61e of partition level 2 overlap with partition sets 51a and 51b of partition level 1, respectively, so that partition sets 61b and 61e of first partition mode 1 in partition level 2 The partition information indicated may not be defined. In addition, the partition sets 62a, 62b, 62c, 62d, 62e, and 62f of the first partition mode 2 of partition level 2 have opposite widths of coding units of 1: 7, 2: 6, 3: 5, 5: It may include rectangular partitions (index 0, 1) divided into 3, 6: 2, and 7: 1. However, in the first partition mode 1, partition sets 62b and 62e of partition level 2 overlap with partition sets 52a and 52b of partition level 1, so partition sets 62b and 62e of first partition mode 1 in partition level 2 The partition information indicated may not be defined.

In view of space, the first partition modes 3, 4, 5, 6, and 7 of partition level 2 are not shown, but in the first partition mode 3 of partition level 2, at least one of an opposing height and an opposing width of a coding unit. Is divided into 1: 7, 2: 6, 3: 5, 4: 4, 5: 3, 6: 2, 7: 1, and quadrature partitions in which a coding unit is divided into four horizontally and vertically directions may be defined.

In addition, in the first partition mode 4 of partition level 2, the first partition mode 4 is positioned at the upper left of the coding unit, and at least one of the left height and the top width of the coding unit is 1: 7, 2: 6, 3: 5, 4: 4, 5 A rectangular partition of size divided into: 3, 6: 2, 7: 1 and a non-rectangular partition of the remaining pieces can be defined.

In the first partition mode 5 of partition level 2, located at the upper right of the coding unit, at least one of the right height and the top width of the coding unit is 1: 7, 2: 6, 3: 5, 4: 4, 5: 3 , A partition partition of size 6: 2, 7: 1 and a non-rectangular partition of the remaining pieces can be defined.

In the first partition mode 6 of partition level 2, located at the lower left of the coding unit, at least one of the left height and the bottom width of the coding unit is 1: 7, 2: 6, 3: 5, 4: 4, 5: 3 , A partition partition of size 6: 2, 7: 1 and a non-rectangular partition of the remaining pieces can be defined.

In the first partition mode 7 of partition level 2, at least one of the right height and the bottom width of the coding unit is 1: 7, 2: 6, 3: 5, 4: 4, 5: 3, 6: 2, 7: 1 Partitioned into, one rectangular partition and a non-rectangular partition of the remaining pieces may be defined at the lower right of the coding unit.

If the encoding size is large enough, the partition set can be extended to partition level 3 and partition level 4.

Therefore, in the tree structure 50 of the partition according to an embodiment, the shape and orientation of the partition may be determined based on the first partition mode, and the minimum width and the minimum height of the partition may be determined based on the partition level. Rectangular partitions determined based on the first partition mode and partition level may include partitions having a partition width that is a multiple of the minimum width and a partition height that is a multiple of the minimum height. In this case, the second partition mode may refer to a partition having a predetermined width or height among the partitions determined based on the first partition mode and the partition level.

When one coding unit includes two or more partitions, the width or height of the remaining partition is determined based on the width or height of the partition having index 0, so that the width or height of the partition having index 0 is for convenience of description. Only talk about height.

For example, in the tree structure 50 of the partition according to an embodiment, the partitions 51a and 51b of the first partition mode 1 of the partition level 1 may have a minimum height of 1/4 of the height of the coding unit. Is determined. The heights of the partitions 51a and 51b of the first partition mode 1 of partition level 1 are one and three times the minimum height of the partition, respectively. In this case, the second partition mode may be defined to point to each of partition 51a and partition 51b of first partition mode 1 of partition level 1.

In a similar manner, in the first partition mode 4 of partition level 1, the minimum width and minimum height of the rectangular partition are determined to be 1/4 of the width and height of the coding unit, and one rectangular partition (left) With index 0), the remaining pieces of non-rectangular partition (index 1) can be formed. The second partition mode of partition level 1, the first partition mode 4, partitions 54a, 54b, 54c, 54d, 54f, wherein at least one of the width and height of the partition is determined to vary by one, two or three times the minimum value. , 54g, 54h, 54i may be defined to indicate each. As described above, in the first partition mode 4, partition 54e of partition level 1 is not used.

However, in partition level 0, the second partition mode does not need to be defined separately. In addition, since the types of partitions that may exist according to the first partition mode or the partition level vary, the number, range, etc. of the second partition modes may vary.

The video encoding apparatus 10 according to an embodiment determines prediction of one partition among partitions constituting the tree structure 50, thereby enabling prediction encoding based on partitions of various shapes, directions, and sizes. However, in the trade-off between the accuracy of the prediction encoding and the computation speed of the video encoding apparatus 10, when the computation speed is more important, the video encoding apparatus 10 according to an embodiment may determine the partitions included in the tree structure 50. The selection range of the first partition mode, partition level, or second partition mode may be limited.

The video encoding apparatus 10 according to an embodiment may encode partition information such as a first partition mode, a partition level, and a second partition mode of each partition while encoding prediction mode information, a motion vector, and a residual of the partition. have. Accordingly, the video decoding apparatus 11 according to an embodiment may determine a partition based on the extracted partition information, and perform prediction decoding using the partition.

The partition of the minimum size according to an embodiment may be a partition having a minimum coding unit divided into four parts. The size of a partition according to an embodiment may be determined based on the partition level, but since the size of the partition should be greater than or equal to the minimum size of the partition and less than or equal to the coding unit, the size of the partition is dependent on the size of the coding unit. Therefore, the partition level may also be related to the size of the coding unit.

In addition, a partition for predicting the motion of the small region is required in the region within the coding unit having a small size. However, since the larger the coding unit, the motion of the large region to the small region may occur in the region within the coding unit. Therefore, the larger the coding unit, the more predictive coding using the larger partition to the smaller partition is necessary. Therefore, it is preferable that the partition level is also determined based on the size of the coding unit.

Therefore, based on the size of the coding unit according to an embodiment, the relationship between the definable partition level is shown in Table 1.

Coding unit size Partition level = 0 Partition level = 1 Partition level = 2 Partition level = 3 Partition level = 4 128 x 128 o o o o o 64 x 64 o o o o x 32 x 32 o o o x x 16 x 16 o o x x x 8x8 o x x x x

Therefore, only partitions of partition level 0, which is the lowest partition level, may be determined for a coding unit having a size of 8 × 8. Partitions of partition levels 0 and 1 may be determined for a coding unit having a size of 16 × 16. For coding units having sizes 32x32, 64x64, and 128x128, partitions from partition level 0 to partition levels 2, 3, and 4 may be determined, respectively. Accordingly, the partition level may be variably allowed based on the size of the coding unit. FIG. 5 illustrates a relationship between a first partition mode, a partition level, and a second partition mode. That is, the types of the first partition mode and the second partition mode, which may be defined according to the partition level, may be determined using points inside the coding units 71, 72, and 73 illustrated in FIG. 5.

In FIG. 5, a line inside the coding units 71, 72, and 73 represents a line that may become the height or width of a partition included in the coding units 71, 72, and 73, and a dot represents a width and a height of the partition. Indicates an intersection. For example, when a straight line reaching a width or a height of the coding units 71, 72, 73 along a line inside the coding units 71, 72, 73 from a predetermined intersection point in the coding units 71, 72, 73 is encoded. Partitions in which the units 71, 72, and 73 are divided may be formed.

For example, at partition level 0, the lines in the coding unit 71 are lines dividing the height or width of the coding unit 71 by two. Lines intersect in the coding unit 71 to form one intersection point, and partitions surrounded by a straight line extending from the intersection to two of a left height, a right height, an upper width, or a lower width of the coding unit 71 may be determined. . That is, the intersection of the lines in the coding unit 71 may be a vertex of the partition. Therefore, only one set of partitions may be defined in the coding unit 71 for each first partition mode of partition level 0. FIG. Since only one set of partitions is defined per first partition mode, the second partition mode may not be set.

In addition, at partition level 1, the lines in the coding unit 72 are lines that divide the height or the width of the coding unit 72 into four. Nine partition vertices may be generated as the lines in the coding unit 72 intersect, but a partition may be generated based on eight vertices except for an intersection point (white intersection point) that overlaps with partition level 0. FIG. Therefore, eight partition sets may be defined in the coding unit 72 for each first partition mode of the partition level 1.

In a similar manner, at partition level 2, the lines in the coding unit 73 are lines that divide the height or width of the coding unit 73 by eight. 49 partition vertices may be generated as the lines in the coding unit 73 intersect, but a partition may be generated based on 40 vertices except for 9 intersection points (white intersection points) that overlap with upper partition level 0 and partition level 1. have. Therefore, 40 partition sets may be defined in the coding unit 72 for each first partition mode of the partition level 2.

Therefore, according to the partition level, the number of second partition modes included in one first partition mode may correspond to the number of vertices.

6 is a flowchart of a video encoding method using a variable partition for predictive encoding according to an embodiment of the present invention.

In operation 81, a prediction encoding is performed on partitions determined based on a first partition mode and a partition level for each coding unit that is a data unit for encoding a picture, thereby determining a partition to output an encoding result.

The shape and division direction of the partition may be determined based on the first partition mode, and the minimum width or the minimum height of the partition may be determined based on the partition level. By comparing the prediction encoding results for each partition, a partition having the highest encoding efficiency may be determined, and the residual of the determined partition may be encoded.

An allowable range of the partition level may be determined based on the size of the coding unit. According to the first partition mode, a second partition mode for indicating a partition of a predetermined width and height may be further determined. Based on the first partition mode and the partition level, an allowable range of the number of the second partition modes can be determined.

In step 82, partition information indicating the first partition mode and partition level of the partition determined in the previous step 81 is encoded and output. The partition information may further include a second partition mode according to the first partition mode. The motion vector and the residual may be encoded and output for each partition. Encoding information including information about partition information, a prediction mode, and an encoding mode may be encoded and output.

7 is a flowchart of a video decoding method using a variable partition for predictive encoding according to an embodiment of the present invention.

In step 91, partition information indicating a first partition mode and a partition level of a partition is extracted for each coding unit from the received bitstream. The motion vector and the residual may be extracted for each partition by parsing the received bitstream. By encoding the received bitstream, encoding information including information on partition information, prediction mode, and encoding mode may be extracted.

In step 92, prediction decoding is performed using partitions determined based on the first partition mode and the partition level of the partition information extracted in the previous step 91, and the picture is decoded. The first partition mode and partition level may be read from the partition information, and the second partition mode may be read according to the first partition mode. The shape and division direction of the partition may be determined based on the first partition mode, and the width or height of the partition in comparison to the width or height of the coding unit may be determined based on the partition level. A picture may be decoded by decoding a residual of a partition for each partition.

Hereinafter, video encoding and decoding using variable partitions for predictive encoding are disclosed based on coding units having a tree structure according to an embodiment of the present invention with reference to FIGS. 8 to 22.

8 is a block diagram of a video decoding apparatus using a variable partition for predictive encoding based on coding units having a tree structure, according to an embodiment of the present invention.

The video encoding apparatus 100 using merging of data units based on coding units having a tree structure according to an embodiment may include a maximum coding unit splitter 110, a coding unit determiner 120, and an outputter 130. Include. For convenience of description below, the video encoding apparatus 100 using the merging of data units based on coding units having a tree structure according to an embodiment may be referred to as a video encoding apparatus 100.

The maximum coding unit splitter 110 may partition the current picture based on the maximum coding unit that is a coding unit of the maximum size for the current picture of the image. If the current picture is larger than the maximum coding unit, image data of the current picture may be split into at least one maximum coding unit. The maximum coding unit according to an embodiment may be a data unit having a size of 32x32, 64x64, 128x128, 256x256, or the like, and may be a square data unit having a square of two horizontal and vertical sizes. The image data may be output to the coding unit determiner 120 for at least one maximum coding unit.

The coding unit according to an embodiment may be characterized by a maximum size and depth. The depth indicates the number of times the coding unit is spatially divided from the maximum coding unit, and as the depth increases, the coding unit for each depth may be split from the maximum coding unit to the minimum coding unit. The depth of the largest coding unit is the highest depth and the minimum coding unit may be defined as the lowest coding unit. As the maximum coding unit decreases as the depth increases, the size of the coding unit for each depth decreases, and thus, the coding unit of the higher depth may include coding units of a plurality of lower depths.

As described above, the image data of the current picture may be divided into maximum coding units according to the maximum size of the coding unit, and each maximum coding unit may include coding units divided by depths. Since the maximum coding unit is divided according to depths, image data of a spatial domain included in the maximum coding unit may be hierarchically classified according to depths.

The maximum depth and the maximum size of the coding unit that limit the total number of times of hierarchically dividing the height and the width of the maximum coding unit may be preset.

The coding unit determiner 120 encodes at least one divided region obtained by dividing the region of the largest coding unit for each depth, and determines a depth at which the final encoding result is output for each of the at least one divided region. That is, the coding unit determiner 120 encodes the image data in coding units according to depths for each maximum coding unit of the current picture, and selects a depth at which the smallest coding error occurs to determine the coding depth. The determined coded depth and the image data for each maximum coding unit are output to the outputter 130.

Image data in the largest coding unit is encoded based on coding units according to depths according to at least one depth less than or equal to the maximum depth, and encoding results based on the coding units for each depth are compared. As a result of comparing the encoding error of the coding units according to depths, a depth having the smallest encoding error may be selected. At least one coding depth may be determined for each maximum coding unit.

As the depth of the maximum coding unit increases, the coding unit is divided into hierarchically and the number of coding units increases. In addition, even in the case of coding units having the same depth included in one largest coding unit, a coding error of each data is measured, and whether or not division into a lower depth is determined. Therefore, even in the data included in one largest coding unit, since the encoding error for each depth is different according to the position, the coding depth may be differently determined according to the position. Accordingly, one or more coding depths may be set for one maximum coding unit, and data of the maximum coding unit may be partitioned according to coding units of one or more coding depths.

Accordingly, the coding unit determiner 120 according to an embodiment may determine coding units having a tree structure included in the current maximum coding unit. The coding units having a tree structure according to an embodiment include coding units having a depth determined as a coding depth among all deeper coding units included in the maximum coding unit. The coding unit of the coding depth may be hierarchically determined according to the depth in the same region within the maximum coding unit, and may be independently determined for the other regions. Similarly, the coded depth for the current region may be determined independently of the coded depth for the other region.

The maximum depth according to an embodiment is an index related to the number of divisions from the maximum coding unit to the minimum coding unit. The first maximum depth according to an embodiment may represent the total number of divisions from the maximum coding unit to the minimum coding unit. The second maximum depth according to an embodiment may represent the total number of depth levels from the maximum coding unit to the minimum coding unit. For example, when the depth of the largest coding unit is 0, the depth of the coding unit obtained by dividing the largest coding unit once may be set to 1, and the depth of the coding unit divided twice may be set to 2. In this case, if the coding unit divided four times from the maximum coding unit is the minimum coding unit, since depth levels of 0, 1, 2, 3, and 4 exist, the first maximum depth is set to 4 and the second maximum depth is set to 5. Can be.

Predictive encoding and transformation of the largest coding unit may be performed. Similarly, prediction encoding and transformation are performed based on depth-wise coding units for each maximum coding unit and for each depth less than or equal to the maximum depth. According to an embodiment, the transform performed for video encoding may include a frequency transform, an orthogonal transform, an integer transform, and the like.

Since the number of coding units for each depth increases each time the maximum coding unit is divided for each depth, encoding including prediction encoding and transformation should be performed on all the coding units for each depth generated as the depth deepens. For convenience of explanation, the prediction encoding and the transformation will be described based on the coding unit of the current depth among at least one maximum coding unit.

The video encoding apparatus 100 according to an embodiment may variously select a size or shape of a data unit for encoding image data. The encoding of the image data is performed through prediction encoding, transforming, entropy encoding, and the like. The same data unit may be used in every step, or the data unit may be changed in steps.

For example, the video encoding apparatus 100 may select not only a coding unit for encoding the image data, but also a data unit different from the coding unit in order to perform predictive encoding of the image data in the coding unit.

For prediction encoding of the largest coding unit, prediction encoding may be performed based on a coding unit of a coded depth, that is, a coding unit that is no longer split. Hereinafter, a coding unit that is no longer divided based on prediction coding is referred to as a 'prediction unit'. The partition in which the prediction unit is divided may include a data unit in which at least one of the prediction unit and the height and the width of the prediction unit are divided.

For example, when a coding unit having a size of 2Nx2N (where N is a positive integer) is no longer split, it becomes a prediction unit of size 2Nx2N, and the size of a partition may be 2Nx2N, 2NxN, Nx2N, NxN, or the like. According to an embodiment, the partition type includes not only symmetric partitions in which the height or width of the prediction unit is divided by a symmetrical ratio, but also partitions divided in an asymmetrical ratio, such as 1: n or n: 1, by a geometric form. It may optionally include partitioned partitions, arbitrary types of partitions, and the like.

In addition, the prediction unit according to an embodiment may include the partitions described above with reference to FIGS. 1 to 7. That is, the shape and splitting direction of the prediction unit may be determined based on the first partition mode, and the ratio of the size of the prediction unit to the size of the coding unit may be determined based on the partition level. An allowable range of the partition level, that is, an upper limit or a lower limit of the partition level may be determined according to the size of a coding unit.

According to the first partition mode, a second partition mode for indicating the type of a detailed partition may be determined.

The video encoding apparatus 100 according to an embodiment performs prediction encoding using prediction units constituting a tree structure based on a hierarchical relationship between a first partition mode and a partition level, and compares prediction results, thereby encoding efficiency. This highest partition can be determined. The video encoding apparatus 100 according to an embodiment may determine a partition having a highest partitioning efficiency and a first partition mode for each coding unit.

The prediction mode of the prediction unit may be at least one of an intra mode, an inter mode, and a skip mode. For example, the intra mode and the inter mode may be performed on partitions having sizes of 2N × 2N, 2N × N, N × 2N, and N × N. In addition, the skip mode may be performed only for partitions having a size of 2N × 2N. The encoding may be performed independently for each prediction unit within the coding unit to select a prediction mode having the smallest encoding error.

Also, the video encoding apparatus 100 according to an embodiment may perform conversion of image data of a coding unit based on not only a coding unit for encoding image data, but also a data unit different from the coding unit.

In order to transform the coding unit, the transformation may be performed based on a transformation unit having a size smaller than or equal to the coding unit. For example, the transformation unit may include a data unit for intra mode and a transformation unit for inter mode.

In a similar manner to the coding unit according to the tree structure according to an embodiment, the transformation unit in the coding unit is also recursively divided into smaller transformation units, so that the residual data of the coding unit is determined according to the tree structure according to the transformation depth. Can be partitioned according to the conversion unit.

For a transform unit according to an embodiment, a transform depth indicating a number of divisions between the height and the width of the coding unit divided to the transform unit may be set. For example, if the size of the transform unit of the current coding unit of size 2Nx2N is 2Nx2N, the transform depth is 0, the transform depth 1 if the size of the transform unit is NxN, and the transform depth 2 if the size of the transform unit is N / 2xN / 2. Can be. That is, the transformation unit having a tree structure may also be set for the transformation unit according to the transformation depth.

The encoded information for each coded depth requires not only the coded depth but also prediction related information and transformation related information. Accordingly, the coding unit determiner 120 may determine not only the coded depth that generated the minimum coding error, but also a partition type obtained by dividing a prediction unit into partitions, a prediction mode for each prediction unit, and a size of a transformation unit for transformation.

A method of determining a coding unit and a partition according to a tree structure of a maximum coding unit, according to an embodiment, will be described in detail later with reference to FIGS. 11 through 12.

The coding unit determiner 120 may measure a coding error of coding units according to depths using a Lagrangian Multiplier-based rate-distortion optimization technique.

The output unit 130 outputs the image data of the maximum coding unit encoded based on the at least one coded depth determined by the coding unit determiner 120 and the information about the encoding modes according to depths in the form of a bit stream.

The encoded image data may be a result of encoding residual data of the image.

The information about the encoding modes according to depths may include encoding depth information, partition type information of a prediction unit, prediction mode information, size information of a transformation unit, and the like.

The coded depth information may be defined using depth-specific segmentation information indicating whether to encode to a coding unit of a lower depth without encoding to the current depth. If the current depth of the current coding unit is a coding depth, since the current coding unit is encoded in a coding unit of the current depth, split information of the current depth may be defined so that it is no longer divided into lower depths. On the contrary, if the current depth of the current coding unit is not the coding depth, encoding should be attempted using the coding unit of the lower depth, and thus split information of the current depth may be defined to be divided into coding units of the lower depth.

If the current depth is not the coded depth, encoding is performed on the coding unit divided into the coding units of the lower depth. Since at least one coding unit of a lower depth exists in the coding unit of the current depth, encoding may be repeatedly performed for each coding unit of each lower depth, and recursive coding may be performed for each coding unit of the same depth.

Since coding units having a tree structure are determined in one largest coding unit and information about at least one coding mode should be determined for each coding unit of a coding depth, information about at least one coding mode may be determined for one maximum coding unit. Can be. In addition, since the data of the largest coding unit is divided hierarchically according to the depth, the coding depth may be different for each location, and thus information about the coded depth and the coding mode may be set for the data.

Accordingly, the output unit 130 according to an embodiment may allocate encoding information about a corresponding coding depth and an encoding mode to at least one of a coding unit, a prediction unit, and a minimum unit included in the maximum coding unit. .

The minimum unit according to an embodiment is a square data unit having a size obtained by dividing the minimum coding unit, which is the lowest coding depth, into four divisions. The minimum unit according to an embodiment may be a square data unit having a maximum size that may be included in all coding units, prediction units, partition units, and transformation units included in the maximum coding unit.

For example, the encoding information output through the output unit 130 may be classified into encoding information for each coding unit and encoding information for each prediction unit. The encoding information for each coding unit may include prediction mode information and partition size information. The encoding information transmitted for each prediction unit includes information about an estimation direction of the inter mode, information about a reference image index of the inter mode, information about a motion vector, information about a chroma component of an intra mode, and information about an inter mode of an intra mode. And the like. In addition, information about a maximum size and information about a maximum depth of a coding unit defined for each picture, slice, or GOP may be inserted in a header of a bitstream.

In addition, when the prediction unit is determined based on the first partition mode, partition level, etc. described above with reference to FIGS. 1 to 7, the outputter 130 encodes partition information including the first partition mode and the partition level of the partition. It can be encoded and output as information. The output unit 130 may encode and output the motion vector and the residual for each prediction unit.

According to an embodiment of the simplest form of the video encoding apparatus 100, a coding unit according to depths is a coding unit having a size in which a height and a width of a coding unit of one layer higher depth are divided by half. That is, if the size of the coding unit of the current depth is 2Nx2N, the size of the coding unit of the lower depth is NxN. In addition, the current coding unit having a size of 2N × 2N may include up to four lower depth coding units having a size of N × N.

Accordingly, the video encoding apparatus 100 determines a coding unit having an optimal shape and size for each maximum coding unit based on the size and the maximum depth of the maximum coding unit determined in consideration of the characteristics of the current picture. Coding units may be configured. In addition, since each of the maximum coding units may be encoded in various prediction modes and transformation methods, an optimal coding mode may be determined in consideration of image characteristics of coding units having various image sizes.

Further, based on various sizes of the coding unit, the prediction unit and the type of partition in which the coding unit is divided may also be diversified based on the first partition mode, the partition level, the second partition mode, and so on. Based on predictive coding is possible.

9 is a block diagram of a video decoding apparatus using a variable partition for predictive coding based on coding units having a tree structure, according to an embodiment of the present invention.

The video decoding apparatus 200 using merging of data units based on coding units having a tree structure according to an embodiment may include a receiver 210, image data and encoding information extractor 220, and image data decoder 230. It includes. For convenience of description below, the video decoding apparatus 200 using merge of data units based on coding units having a tree structure according to an embodiment is referred to as a video decoding apparatus 200.

Definitions of various terms such as coding units, depths, prediction units, transformation units, and information about various encoding modes for various processings of the video decoding apparatus 200 according to an embodiment may be described with reference to FIG. 19 and the video encoding apparatus 100. Same as described above with reference.

The receiver 205 receives and parses a bitstream of an encoded video. The image data and encoding information extractor 220 extracts image data encoded for each coding unit from the parsed bitstream according to coding units having a tree structure for each maximum coding unit, and outputs the encoded image data to the image data decoder 230. The image data and encoding information extractor 220 may extract information about a maximum size of a coding unit of the current picture from a header for the current picture.

Also, the image data and encoding information extractor 220 extracts information about a coded depth and an encoding mode for the coding units having a tree structure for each maximum coding unit, from the parsed bitstream. The extracted information about the coded depth and the coding mode is output to the image data decoder 230. That is, the image data of the bit string may be divided into maximum coding units so that the image data decoder 230 may decode the image data for each maximum coding unit.

The information about the coded depth and the encoding mode for each largest coding unit may be set with respect to one or more coded depth information, and the information about the coding mode according to the coded depths may include partition type information, prediction mode information, and transformation unit of the corresponding coding unit. May include size information and the like. Also, the encoding information about the coding depth and the encoding mode according to an embodiment may further include merge related information about the current prediction unit or the current partition.

The information about the coded depth and the encoding mode according to the maximum coding units extracted by the image data and the encoding information extractor 220 may be encoded according to the depth according to the maximum coding unit, as in the video encoding apparatus 100 according to an embodiment. Information about a coded depth and an encoding mode determined to repeatedly perform encoding for each unit to generate a minimum encoding error. Therefore, the video decoding apparatus 200 may reconstruct an image by decoding data according to an encoding method that generates a minimum encoding error.

Since the encoded information about the coded depth and the encoding mode according to an embodiment may be allocated to a predetermined data unit among the corresponding coding unit, the prediction unit, and the minimum unit, the image data and the encoding information extractor 220 may determine the predetermined data. Information about a coded depth and an encoding mode may be extracted for each unit. If the information about the coded depth and the coding mode of the maximum coding unit is recorded for each of the predetermined data units, the predetermined data units having the information about the same coded depth and the coding mode are inferred as data units included in the same maximum coding unit. Can be.

The information about an encoding mode according to an embodiment may include partition information including a first partition mode and a partition level.

The image data decoder 230 reconstructs the current picture by decoding image data of each maximum coding unit based on the information about the coded depth and the encoding mode for each maximum coding unit. That is, the image data decoder 230 may decode the encoded image data based on the read partition type, the prediction mode, and the transformation unit for each coding unit among the coding units having the tree structure included in the maximum coding unit. Can be. The decoding process may include a prediction process including intra prediction and motion compensation, and an inverse transform process.

The image data decoder 230 may perform intra prediction or motion compensation according to each partition and prediction mode for each coding unit based on partition type information and prediction mode information of the prediction unit of the coding unit for each coding depth. .

The image data decoder 230 according to an embodiment may read partition information among information about an encoding mode, and determine a partition defined based on a first partition mode and a partition level among partition information. The image data decoder 230 determines a shape and a splitting direction of the prediction unit based on the first partition mode, and determines a size ratio of the prediction unit to the size of the coding unit based on the partition level. You can decide. According to the first partition mode, the image data decoder 230 may determine the partition in consideration of the second partition mode for indicating the type of the detailed partition.

The first partition mode, the partition level, and the second partition mode, according to an embodiment, perform predictive encoding using prediction units constituting a tree structure based on a hierarchical relationship between the first partition mode and the partition level in the encoding process. By comparing the prediction results, partitions determined to have the highest coding efficiency are defined. Accordingly, the image data decoder 230 according to an embodiment may perform prediction decoding by using a partition having a first partition mode and a partition level having the highest coding efficiency for each coding unit.

In addition, the image data decoder 230 reads a transform unit having a tree structure including the size information of the transform unit of the coding unit for each coded depth, for the inverse transform for each largest coding unit, and based on the transform unit for each coding unit. Inverse transformation can be performed.

The image data decoder 230 may determine the coded depth of the current maximum coding unit by using the split information for each depth. If the split information indicates that the split information is no longer split at the current depth, the current depth is the coded depth. Therefore, the image data decoder 230 may decode the coding unit of the current depth using the partition type, the prediction mode, and the transformation unit size information of the prediction unit with respect to the image data of the current maximum coding unit.

In other words, by observing the encoding information set for a predetermined data unit among the coding unit, the prediction unit, and the minimum unit, the data units having the encoding information including the same split information are gathered, and the image data decoder 230 It may be regarded as one data unit to be decoded in the same encoding mode.

According to an embodiment, the video decoding apparatus 200 obtains encoding information on a coding unit that generates a minimum coding error by recursively encoding each maximum coding unit in an encoding process, and uses the same to decode the current picture. Can be. That is, decoding of encoded image data of coding units having a tree structure determined as an optimal coding unit for each maximum coding unit can be performed.

In addition, the video decoding apparatus 200 according to an embodiment extracts and reads partition information on a determination method of a partition determined by comparing prediction encoding results of prediction units having a tree structure, and performs prediction decoding using partition information. As a result, accurate decoding is possible.

Hereinafter, a method of determining coding units, a prediction unit, and a transformation unit according to a tree structure according to an embodiment of the present invention will be described with reference to FIGS. 10 to 20.

10 illustrates a concept of coding units, according to an embodiment of the present invention.

As an example of a coding unit, a size of a coding unit may be expressed by a width x height, and may include 32x32, 16x16, and 8x8 from a coding unit having a size of 64x64. Coding units of size 64x64 may be partitioned into partitions of size 64x64, 64x32, 32x64, and 32x32, coding units of size 32x32 are partitions of size 32x32, 32x16, 16x32, and 16x16, and coding units of size 16x16 are 16x16. Coding units of size 8x8 may be divided into partitions of size 8x8, 8x4, 4x8, and 4x4, into partitions of 16x8, 8x16, and 8x8.

As for the video data 310, the resolution is set to 1920x1080, the maximum size of the coding unit is 64, and the maximum depth is 2. For the video data 320, the resolution is set to 1920x1080, the maximum size of the coding unit is 64, and the maximum depth is 3. As for the video data 330, the resolution is set to 352x288, the maximum size of the coding unit is 16, and the maximum depth is 1. The maximum depth represents the total number of divisions from the maximum coding unit to the minimum coding unit.

When the resolution is high or the amount of data is large, it is preferable that the maximum size of the coding size is relatively large in order to not only improve coding efficiency but also accurately reflect image characteristics. Accordingly, the video data 310 or 320 having a higher resolution than the video data 330 may be selected to have a maximum size of 64.

Since the maximum depth of the video data 310 is 2, the coding unit 315 of the video data 310 is divided twice from a maximum coding unit having a long axis size of 64, and the depth is deepened by two layers, so that the long axis size is 32, 16. Up to coding units may be included. On the other hand, since the maximum depth of the video data 330 is 1, the coding unit 335 of the video data 330 is divided once from coding units having a long axis size of 16, and the depth is deepened by one layer to increase the long axis size to 8. Up to coding units may be included.

Since the maximum depth of the video data 320 is 3, the coding unit 325 of the video data 320 is divided three times from the largest coding unit having a long axis size of 64, and the depth is three layers deep, so that the long axis size is 32, 16. , Up to 8 coding units may be included. As the depth increases, the expressive power of the detailed information may be improved.

11 is a block diagram of an image encoder based on coding units, according to an embodiment of the present invention.

The image encoder 400 according to an embodiment includes operations performed by the encoding unit determiner 120 of the video encoding apparatus 100 to encode image data. That is, the intra predictor 410 performs intra prediction on the coding unit of the intra mode among the current frame 405, and the motion estimator 420 and the motion compensator 425 are the current frame 405 of the inter mode. And the inter frame estimation and motion compensation using the reference frame 495.

Data output from the intra predictor 410, the motion estimator 420, and the motion compensator 425 is output as a quantized transform coefficient through the frequency converter 430 and the quantizer 440. The quantized transform coefficients are restored to the data of the spatial domain through the inverse quantizer 460 and the frequency inverse transformer 470, and the recovered data of the spatial domain is passed through the deblocking block 480 and the loop filtering unit 490. It is post-processed and output to the reference frame 495. The quantized transform coefficients may be output to the bitstream 455 via the entropy encoder 450.

In order to be applied to the video encoding apparatus 100 according to an embodiment, an intra predictor 410, a motion estimator 420, a motion compensator 425, and a frequency converter that are components of the image encoder 400 may be used. 430, quantization unit 440, entropy encoding unit 450, inverse quantization unit 460, frequency inverse transform unit 470, deblocking unit 480, and loop filtering unit 490 are all the maximum coding units. In each case, an operation based on each coding unit among the coding units having a tree structure should be performed in consideration of the maximum depth.

In particular, the intra predictor 410, the motion estimator 420, and the motion compensator 425 partition each coding unit among coding units having a tree structure in consideration of the maximum size and the maximum depth of the current maximum coding unit. And a prediction mode, and the frequency converter 430 should determine the size of a transform unit in each coding unit among the coding units having a tree structure.

12 is a block diagram of an image decoder based on coding units, according to an embodiment of the present invention.

The bitstream 505 is parsed through the parsing unit 510, and the encoded image data to be decoded and information about encoding necessary for decoding are parsed. The encoded image data is output as inverse quantized data through the entropy decoder 520 and the inverse quantizer 530, and the image data of the spatial domain is restored through the frequency inverse transformer 540.

For the image data of the spatial domain, the intra prediction unit 550 performs intra prediction on the coding unit of the intra mode, and the motion compensator 560 uses the reference frame 585 together to apply the coding unit of the inter mode. Perform motion compensation for the

Data in the spatial domain that has passed through the intra predictor 550 and the motion compensator 560 may be post-processed through the deblocking unit 570 and the loop filtering unit 580 to be output to the reconstructed frame 595. In addition, the post-processed data through the deblocking unit 570 and the loop filtering unit 580 may be output as the reference frame 585.

In order to decode the image data in the image data decoder 230 of the video decoding apparatus 200, step-by-step operations after the parser 510 of the image decoder 500 according to an embodiment may be performed.

In order to be applied to the video decoding apparatus 200 according to an exemplary embodiment, the parser 510, the entropy decoder 520, the inverse quantizer 530, and the frequency inverse transform unit which are components of the image decoder 400 may be used. 540, the intra predictor 550, the motion compensator 560, the deblocking unit 570, and the loop filtering unit 580 all perform operations based on coding units having a tree structure for each largest coding unit. shall.

In particular, the intra predictor 550 and the motion compensator 560 determine partitions and prediction modes for each coding unit having a tree structure, and the frequency inverse transform unit 540 must determine the size of the transform unit for each coding unit. do.

13 is a diagram of deeper coding units according to depths, and partitions, according to an embodiment of the present invention.

The video encoding apparatus 100 according to an embodiment and the video decoding apparatus 200 according to an embodiment use hierarchical coding units to consider image characteristics. The maximum height, width, and maximum depth of the coding unit may be adaptively determined according to the characteristics of the image, and may be variously set according to a user's request. According to the maximum size of the preset coding unit, the size of the coding unit for each depth may be determined.

The hierarchical structure 600 of a coding unit according to an embodiment illustrates a case in which a maximum height and a width of a coding unit are 64 and a maximum depth is four. In this case, the maximum depth indicates the total number of divisions from the maximum coding unit to the minimum coding unit. Since the depth deepens along the vertical axis of the hierarchical structure 600 of the coding unit according to an embodiment, the height and the width of the coding unit for each depth are divided. In addition, a prediction unit and a partition on which the prediction encoding of each depth-based coding unit is shown along the horizontal axis of the hierarchical structure 600 of the coding unit are illustrated.

That is, the coding unit 610 has a depth of 0 as the largest coding unit of the hierarchical structure 600 of the coding unit, and the size, ie, the height and width, of the coding unit is 64x64. The depth is deeper along the vertical axis, the coding unit 620 of depth 1 having a size of 32x32, the coding unit 630 of depth 2 having a size of 16x16, the coding unit 640 of depth 3 having a size of 8x8, and the depth 4 of depth 4x4. The coding unit 650 exists. A coding unit 650 having a depth of 4 having a size of 4 × 4 is a minimum coding unit.

Prediction units and partitions of the coding unit are arranged along the horizontal axis for each depth. That is, if the coding unit 610 of size 64x64 having a depth of zero is a prediction unit, the prediction unit may include a partition 610 of size 64x64, partitions 612 of size 64x32, and size included in the coding unit 610 of size 64x64. 32x64 partitions 614, 32x32 partitions 616.

Similarly, the prediction unit of the coding unit 620 having a size of 32x32 having a depth of 1 includes a partition 620 of size 32x32, partitions 622 of size 32x16 and a partition of size 16x32 included in the coding unit 620 of size 32x32. 624, partitions 626 of size 16x16.

Similarly, the prediction unit of the coding unit 630 of size 16x16 having a depth of 2 includes a partition 630 of size 16x16, partitions 632 of size 16x8, and a partition of size 8x16 included in the coding unit 630 of size 16x16. 634, partitions 636 of size 8x8.

Similarly, the prediction unit of the coding unit 640 of size 8x8 having a depth of 3 includes a partition 640 of size 8x8, partitions 642 of size 8x4 and a partition of size 4x8 included in the coding unit 640 of size 8x8. 644, partitions 646 of size 4x4.

Finally, the coding unit 650 of size 4x4 having a depth of 4 is the minimum coding unit and the coding unit of the lowest depth, and the corresponding prediction unit may also be set only as the partition 650 having a size of 4x4. Further, partitions 652 of size 4x2, partitions 654 of size 2x4, and partitions 656 of size 2x2 may be used.

Since the partitions shown in FIG. 13 have at least one of a height and a width of each coding unit divided into 1/2, the first partition modes 0, 1, 2, of partition level 0 with reference to FIGS. 3 may correspond to partition sets 40, 41, 42, and 43. For example, partitions 610, 620, 630, 640 and 650 correspond to partition set 40 of the first partition mode 0 of partition level 0, and partitions 612, 622, 632, 642 and 652 correspond to the first partition of partition level 0 It may correspond to partition set 41 of mode 1. FIG. Partitions 614, 624, 634, 644, and 654 correspond to partition set 42 of the first partition mode 2 of partition level 0, and partitions 616, 626, 636, 646, and 656 partitions of the first partition mode 3 of partition level 0 May correspond to set 43.

The coding unit determiner 120 of the video encoding apparatus 100 according to an exemplary embodiment may determine a coding depth of the maximum coding unit 610. The coding unit of each depth included in the maximum coding unit 610. Encoding must be performed every time.

The number of deeper coding units according to depths for including data having the same range and size increases as the depth increases. For example, four coding units of depth 2 are required for data included in one coding unit of depth 1. Therefore, in order to compare the encoding results of the same data for each depth, each of the coding units having one depth 1 and four coding units having four depths 2 should be encoded.

For each depth coding, encoding may be performed for each prediction unit of a coding unit according to depths along a horizontal axis of the hierarchical structure 600 of the coding unit, and a representative coding error, which is the smallest coding error at a corresponding depth, may be selected. . In addition, a depth deeper along the vertical axis of the hierarchical structure 600 of the coding unit, the encoding may be performed for each depth, and the minimum coding error may be searched by comparing the representative coding error for each depth. The depth and the partition in which the minimum coding error occurs in the maximum coding unit 610 may be selected as the coding depth and the partition type of the maximum coding unit 610.

14 illustrates a relationship between a coding unit and transformation units, according to an embodiment of the present invention.

The video encoding apparatus 100 according to an embodiment or the video decoding apparatus 200 according to an embodiment encodes or decodes an image in coding units having a size smaller than or equal to the maximum coding unit for each maximum coding unit. The size of a transformation unit for transformation in the encoding process may be selected based on a data unit that is not larger than each coding unit.

For example, in the video encoding apparatus 100 or the video decoding apparatus 200 according to the embodiment, when the current coding unit 710 is 64x64 size, the 32x32 size conversion unit 720 is The conversion can be performed.

In addition, the data of the 64x64 coding unit 710 is transformed into 32x32, 16x16, 8x8, and 4x4 transform units of 64x64 size or less, and then encoded, and the transform unit having the least error with the original is selected. Can be.

FIG. 15 illustrates encoding information according to depths, according to an embodiment of the present invention.

The output unit 130 of the video encoding apparatus 100 according to an exemplary embodiment is information about an encoding mode, and information about a partition type 800 and information 810 about a prediction mode for each coding unit of each coded depth. The information 820 about the size of the transformation unit may be encoded and transmitted.

The information about the partition type 800 is a data unit for predictive encoding of the current coding unit and indicates information about a partition type in which the prediction unit of the current coding unit is divided. For example, the current coding unit CU_0 of size 2Nx2N may be any one of a partition 802 of size 2Nx2N, a partition 804 of size 2NxN, a partition 806 of size Nx2N, and a partition 808 of size NxN. It can be divided and used. In this case, the information 800 about the partition type of the current coding unit represents one of a partition 802 of size 2Nx2N, a partition 804 of size 2NxN, a partition 806 of size Nx2N, and a partition 808 of size NxN. It is set to.

Information 810 relating to the prediction mode indicates the prediction mode of each partition. For example, through the information 810 about the prediction mode, whether the partition indicated by the information 800 about the partition type is performed in one of the intra mode 812, the inter mode 814, and the skip mode 816 is performed. Whether or not can be set.

In addition, the information about the transform unit size 820 indicates whether to transform the current coding unit based on the transform unit. For example, the transform unit may be one of a first intra transform unit size 822, a second intra transform unit size 824, a first inter transform unit size 826, and a second intra transform unit size 828. have.

The image data and encoding information extractor 210 of the video decoding apparatus 200 according to an embodiment may include information about a partition type 800, information 810 about a prediction mode, and transformation for each depth-based coding unit. Information 820 about the unit size may be extracted and used for decoding.

The information about the partition type 800 may include information about the encoding mode according to an embodiment. For example, the information 800 regarding the partition type may include a partition type determined based on the first partition mode information, the partition level, and the second partition mode information.

16 is a diagram of deeper coding units according to depths, according to an embodiment of the present invention.

Segmentation information may be used to indicate a change in depth. The split information indicates whether a coding unit of a current depth is split into coding units of a lower depth.

The prediction unit 910 for predictive encoding of the coding unit 900 having depth 0 and 2N_0x2N_0 size includes 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 N_0xN_0 It may include a partition type 918 of size. Although only partitions 912, 914, 916, and 918 in which the prediction unit is divided by a symmetrical ratio are illustrated, as described above, the partition type is not limited thereto, and asymmetric partitions, arbitrary partitions, geometric partitions, and the like. It may include.

For each partition type, prediction coding must be performed repeatedly for one 2N_0x2N_0 partition, two 2N_0xN_0 partitions, two N_0x2N_0 partitions, and four N_0xN_0 partitions. For partitions having a size 2N_0x2N_0, a size N_0x2N_0, a size 2N_0xN_0, and a size N_0xN_0, prediction encoding may be performed in an intra mode and an inter mode. The skip mode may be performed only for prediction encoding on partitions having a size of 2N_0x2N_0.

If the encoding error by one of the partition types 912, 914, and 916 of sizes 2N_0x2N_0, 2N_0xN_0, and N_0x2N_0 is the smallest, it is no longer necessary to divide it into lower depths.

If the encoding error of the partition type 918 having the size N_0xN_0 is the smallest, the depth 0 is changed to 1 and split (920), and the encoding is repeatedly performed on the depth 2 and the coding units 930 of the partition type having the size N_0xN_0. We can search for the minimum coding error.

The prediction unit 940 for predictive encoding of the coding unit 930 having a depth of 1 and a size of 2N_1x2N_1 (= N_0xN_0) includes a partition type 942 having a size of 2N_1x2N_1, a partition type 944 having a size of 2N_1xN_1, and a partition type having a size of N_1x2N_1. 946, a partition type 948 of size N_1 × N_1 may be included.

In addition, if the encoding error due to the partition type 948 having the size N_1xN_1 is the smallest, the depth 1 is changed to the depth 2 and divided (950), and repeatedly for the depth 2 and the coding units 960 of the size N_2xN_2. The encoding may be performed to search for a minimum encoding error.

When the maximum depth is d, the split information for each depth may be set until the depth d-1, and the split information may be set up to the depth d-2. That is, when encoding is performed from the depth d-2 to the depth d-1 to the depth d-1, the prediction encoding of the coding unit 980 of the depth d-1 and the size 2N_ (d-1) x2N_ (d-1) The prediction unit for 990 is a partition type 992 of size 2N_ (d-1) x2N_ (d-1), partition type 994 of size 2N_ (d-1) xN_ (d-1), size A partition type 996 of N_ (d-1) x2N_ (d-1) and a partition type 998 of size N_ (d-1) xN_ (d-1) may be included.

Among the partition types, one partition 2N_ (d-1) x2N_ (d-1), two partitions 2N_ (d-1) xN_ (d-1), two sizes N_ (d-1) x2N_ Prediction encoding is repeatedly performed for each partition of (d-1) and four partitions of size N_ (d-1) xN_ (d-1), so that a partition type having a minimum encoding error may be searched. .

Even if the encoding error of the partition type 998 of size N_ (d-1) xN_ (d-1) is the smallest, the maximum depth is d, so the coding unit CU_ (d-1) of the depth d-1 is no longer The encoding depth of the current maximum coding unit 900 may be determined as the depth d-1, and the partition type may be determined as N_ (d-1) xN_ (d-1) without going through a division process into lower depths. In addition, since the maximum depth is d, split information is not set for the coding unit 952 having the depth d-1.

The data unit 999 may be referred to as a 'minimum unit' for the current maximum coding unit. According to an embodiment, the minimum unit may be a square data unit having a size obtained by dividing the minimum coding unit, which is the lowest coding depth, into four divisions. Through this iterative encoding process, the video encoding apparatus 100 compares the encoding errors for each depth of the coding unit 900, selects a depth at which the smallest encoding error occurs, and determines a coding depth. The partition type and the prediction mode may be set to the encoding mode of the coded depth.

In this way, the depth with the smallest error can be determined by comparing the minimum coding errors for all depths of depths 0, 1, ..., d-1, d, and can be determined as the coding depth. The coded depth, the partition type of the prediction unit, and the prediction mode may be encoded and transmitted as information about an encoding mode. In addition, since the coding unit must be split from the depth 0 to the coded depth, only the split information of the coded depth is set to '0', and the split information for each depth except the coded depth should be set to '1'.

The image data and encoding information extractor 220 of the video decoding apparatus 200 according to an embodiment may extract information about a coding depth and a prediction unit for the coding unit 900 and use the same to decode the coding unit 912. Can be. The video decoding apparatus 200 according to an embodiment may identify a depth having split information of '0' as a coding depth using split information for each depth, and may use the decoding depth by using information about an encoding mode for a corresponding depth. have.

17, 18, and 19 illustrate a relationship between a coding unit, a prediction unit, and a transformation unit, according to an embodiment of the present invention.

The coding units 1010 are coding units according to coding depths determined by the video encoding apparatus 100 according to an embodiment with respect to the maximum coding unit. The prediction unit 1060 is partitions of prediction units of each coding depth of each coding depth among the coding units 1010, and the transformation unit 1070 is transformation units of each coding depth for each coding depth.

If the depth-based coding units 1010 have a depth of 0, the coding units 1012 and 1054 have a depth of 1, and the coding units 1014, 1016, 1018, 1028, 1050, and 1052 have depths. 2, coding units 1020, 1022, 1024, 1026, 1030, 1032, and 1048 have a depth of three, and coding units 1040, 1042, 1044, and 1046 have a depth of four.

Some of the partitions 1014, 1016, 1022, 1032, 1048, 1050, 1052, and 1054 of the prediction units 1060 are obtained by splitting coding units. That is, partitions 1014, 1022, 1050, and 1054 are partition types of 2NxN, partitions 1016, 1048, and 1052 are partition types of Nx2N, and partitions 1032 are partition types of NxN. Prediction units and partitions of the coding units 1010 according to depths are smaller than or equal to each coding unit.

The image data of the part 1052 of the transformation units 1070 is transformed or inversely transformed into a data unit having a smaller size than the coding unit. In addition, the transformation units 1014, 1016, 1022, 1032, 1048, 1050, 1052, and 1054 are data units having different sizes or shapes when compared to corresponding prediction units and partitions among the prediction units 1060. That is, the video encoding apparatus 100 according to an embodiment and the video decoding apparatus 200 according to an embodiment may be intra prediction / motion estimation / motion compensation operations and transform / inverse transform operations for the same coding unit. Each can be performed on a separate data unit.

Accordingly, coding is performed recursively for each coding unit having a hierarchical structure for each largest coding unit to determine an optimal coding unit. Thus, coding units having a recursive tree structure may be configured. The encoding information may include split information about a coding unit, partition type information, prediction mode information, and transformation unit size information. Table 2 below shows an example that can be set in the video encoding apparatus 100 and the video decoding apparatus 200 according to an embodiment.

Segmentation information 0 (coding for coding units of size 2Nx2N of current depth d) Split information 1 Prediction mode Partition type Transformation unit size Iterative coding for each coding unit of lower depth d + 1 Intra
Inter

Skip (2Nx2N only) Symmetric Partition Type Asymmetric Partition Type Conversion unit split information 0 Conversion unit
Split information 1 2Nx2N
2NxN
Nx2N
NxN 2NxnU
2NxnD
nLx2N
nRx2N 2Nx2N NxN
(Symmetric partition type)

N / 2xN / 2
(Asymmetric partition type)

The output unit 130 of the video encoding apparatus 100 according to an embodiment outputs encoding information about coding units having a tree structure, and the encoding information extraction unit of the video decoding apparatus 200 according to an embodiment ( 220 may extract encoding information about coding units having a tree structure from the received bitstream. The split information indicates whether the current coding unit is split into coding units having a lower depth. If the split information of the current depth d is 0, partition type information, prediction mode, and transform unit size information are defined for the coded depth because the depth in which the current coding unit is no longer divided into the lower coding units is a coded depth. Can be. If it is to be further split by the split information, encoding should be performed independently for each coding unit of the divided four lower depths.

The prediction mode may be represented by one of an intra mode, an inter mode, and a skip mode. Intra mode and inter mode can be defined in all partition types, and skip mode can be defined only in partition type 2Nx2N.

The partition type information indicates the symmetric partition types 2Nx2N, 2NxN, Nx2N and NxN, in which the height or width of the prediction unit is divided by the symmetrical ratio, and the asymmetric partition types 2NxnU, 2NxnD, nLx2N, nRx2N, which are divided by the asymmetrical ratio. Can be. The asymmetric partition types 2NxnU and 2NxnD are divided into heights 1: 3 and 3: 1, respectively, and the asymmetric partition types nLx2N and nRx2N are divided into 1: 3 and 3: 1 widths, respectively. Referring to the partitions according to the tree structure of FIG. 4, the asymmetric partition types 2NxnU and 2NxnD correspond to partition sets 51a and 51b of the first partition mode 1 of partition level 1, and the asymmetric partition types nLx2N and nRx2N and 2 Corresponding to the partition sets 52a and 52b of the first partition mode 2 of the partition level 1, the conversion unit size may be set to two kinds of sizes in the intra mode and two kinds of sizes in the inter mode. That is, if the transformation unit split information is 0, the size of the transformation unit is set to the size 2Nx2N of the current coding unit. If the transform unit split information is 1, a transform unit having a size obtained by dividing the current coding unit may be set. In addition, if the partition type for the current coding unit having a size of 2Nx2N is a symmetric partition type, the size of the transform unit may be set to NxN, and if the asymmetric partition type is N / 2xN / 2.

Encoding information of coding units having a tree structure according to an embodiment may be allocated to at least one of a coding unit, a prediction unit, and a minimum unit unit of a coding depth. The coding unit of the coding depth may include at least one prediction unit and at least one minimum unit having the same encoding information.

Therefore, if the encoding information held by each adjacent data unit is checked, it may be determined whether the adjacent data units are included in the coding unit having the same coding depth. In addition, since the coding unit of the corresponding coding depth may be identified by using the encoding information held by the data unit, the distribution of the coded depths within the maximum coding unit may be inferred.

Therefore, in this case, when the current coding unit is predicted with reference to the neighboring data unit, the encoding information of the data unit in the depth-specific coding unit adjacent to the current coding unit may be directly referred to and used.

In another embodiment, when the prediction coding is performed by referring to the neighboring coding unit, the data adjacent to the current coding unit in the coding unit according to depths is encoded by using the encoding information of the adjacent coding units according to depths. The neighboring coding unit may be referred to by searching.

20 illustrates a relationship between a coding unit, a prediction unit, and a transformation unit, according to encoding mode information of Table 1. FIG.

The maximum coding unit 1300 includes coding units 1302, 1304, 1306, 1312, 1314, 1316, and 1318 of a coded depth. Since one coding unit 1318 is a coding unit of a coded depth, split information may be set to zero. The partition type information of the coding unit 1318 having a size of 2Nx2N is partition type 2Nx2N 1322, 2NxN 1324, Nx2N 1326, NxN 1328, 2NxnU 1332, 2NxnD 1334, nLx2N (1336). And nRx2N 1338.

This partition type may correspond to some of the partitions specified in FIG. 4. For example, partition type 2Nx2N 1322 may correspond to partition 40 (first partition mode 0 of partition level 0). Partition type 2NxN 1324 and Nx2N 1326 may correspond to partition sets 41 and 42 (first partition levels 1 and 2 of partition level 0, respectively). Partition type NxN 1328 may correspond to partition set 43 (first partition mode 3 of partition level 0). Partition type 2NxnU 1332 and 2NxnD 1334 may correspond to partition sets 51a and 51b (both partition level 1 and first partition mode 1), respectively. The partition types nLx2N 1336 and nRx2N 1338 may correspond to partition sets 52a and 52b (both partition level 1 and first partition mode 2). The conversion unit partition information (TU size flag) is a kind of conversion index. The size of the transform unit corresponding to the transform index may be changed according to the prediction unit type or the partition type of the coding unit.

For example, when the partition type information is set to one of the symmetric partition types 2Nx2N 1322, 2NxN 1324, Nx2N 1326, and NxN 1328, if the conversion unit partition information is 0, a conversion unit of size 2Nx2N ( 1342 is set, and if the transform unit split information is 1, a transform unit 1344 of size NxN may be set.

When the partition type information is set to one of the asymmetric partition types 2NxnU (1332), 2NxnD (1334), nLx2N (1336), and nRx2N (1338), if the conversion unit partition information (TU size flag) is 0, a conversion unit of size 2Nx2N ( 1352 is set, and if the transform unit split information is 1, a transform unit 1354 of size N / 2 × N / 2 may be set.

The conversion unit splitting information (TU size flag) described above with reference to FIG. 18 is a flag having a value of 0 or 1, but the conversion unit splitting information according to an embodiment is not limited to a 1-bit flag and is set to 0 according to a setting. , 1, 2, 3., etc., and may be divided hierarchically. The transformation unit partition information may be used as an embodiment of the transformation index.

In this case, when the transformation unit split information according to an embodiment is used together with the maximum size of the transformation unit and the minimum size of the transformation unit, the size of the transformation unit actually used may be expressed. The video encoding apparatus 100 according to an embodiment may encode maximum transform unit size information, minimum transform unit size information, and maximum transform unit split information. The encoded maximum transform unit size information, minimum transform unit size information, and maximum transform unit split information may be inserted into the SPS. The video decoding apparatus 200 according to an embodiment may use the maximum transform unit size information, the minimum transform unit size information, and the maximum transform unit split information to use for video decoding.

For example, (a) if the current coding unit is 64x64 in size and the maximum transform unit size is 32x32, (a-1) when the transform unit split information is 0, the size of the transform unit is 32x32, (a-2) When the split information is 1, the size of the transform unit may be set to 16 × 16, and (a-3) when the split unit information is 2, the size of the transform unit may be set to 8 × 8.

As another example, (b) if the current coding unit is size 32x32 and the minimum transform unit size is 32x32, (b-1) when the transform unit split information is 0, the size of the transform unit may be set to 32x32. Since the size cannot be smaller than 32x32, no further conversion unit split information can be set.

As another example, (c) if the current coding unit is 64x64 and the maximum transform unit split information is 1, the transform unit split information may be 0 or 1, and no other transform unit split information may be set.

Therefore, when the maximum transform unit split information is defined as 'MaxTransformSizeIndex', the minimum transform unit size is 'MinTransformSize', and the transform unit split information is 0, the minimum transform unit possible in the current coding unit is defined as 'RootTuSize'. The size 'CurrMinTuSize' can be defined as in relation (1) below.

CurrMinTuSize

= max (MinTransformSize, RootTuSize / (2 ^ MaxTransformSizeIndex)) ... (1)

Compared to the minimum transform unit size 'CurrMinTuSize' possible in the current coding unit, 'RootTuSize', which is a transform unit size when the transform unit split information is 0, may indicate a maximum transform unit size that can be adopted in the system. That is, according to relation (1), 'RootTuSize / (2 ^ MaxTransformSizeIndex)' is a transformation obtained by dividing 'RootTuSize', which is the size of the transformation unit when the transformation unit division information is 0, by the number of times corresponding to the maximum transformation unit division information. Since the unit size is 'MinTransformSize' is the minimum transform unit size, a smaller value among them may be the minimum transform unit size 'CurrMinTuSize' possible in the current coding unit.

According to an embodiment, the maximum transform unit size RootTuSize may vary depending on a prediction mode.

For example, if the current prediction mode is the inter mode, RootTuSize may be determined according to the following relation (2). In relation (2), 'MaxTransformSize' represents the maximum transform unit size and 'PUSize' represents the current prediction unit size.

RootTuSize = min (MaxTransformSize, PUSize) ......... (2)

That is, when the current prediction mode is the inter mode, 'RootTuSize', which is a transform unit size when the transform unit split information is 0, may be set to a smaller value among the maximum transform unit size and the current prediction unit size.

If the prediction mode of the current partition unit is a mode when the prediction mode is an intra mode, 'RootTuSize' may be determined according to Equation (3) below. 'PartitionSize' represents the size of the current partition unit.

RootTuSize = min (MaxTransformSize, PartitionSize) ........... (3)

That is, if the current prediction mode is the intra mode, the conversion unit size 'RootTuSize' when the conversion unit split information is 0 may be set to a smaller value among the maximum conversion unit size and the current partition unit size.

However, it should be noted that the current maximum conversion unit size 'RootTuSize' according to an embodiment that changes according to the prediction mode of the partition unit is only an embodiment, and a factor determining the current maximum conversion unit size is not limited thereto.

The prediction unit or partitions described above with reference to FIGS. 10 to 20 may include the first partition modes 0, 1, 2, 3 of partition level 0 and the first partition of partition level 1 of the tree structure 50 of the partitions of FIG. 4. An embodiment is used that is limited to partitions of mode 1 and 2 only. Depending on the system situation and settings, the upper limit of the partition level and the first partition mode may be selectively limited. However, it should be noted that the idea of the present invention is not limited to the partition level and the first partition mode disclosed in FIGS.

21 is a flowchart of a video encoding method using a variable partition for prediction encoding, based on a coding unit having a tree structure, according to an embodiment.

In operation 1210, the current picture of the video may be partitioned into maximum coding units. In operation 1220, the image data is encoded in coding units according to depths, for each largest coding unit of the current picture. Prediction encoding using a tree structure partition based on the first partition mode and the partition level is performed for each coding unit, so that the partition or prediction unit having the highest prediction encoding efficiency may be determined. A coding depth including a prediction error may be selected to determine a coding depth, and coding units having a tree structure including coding units having a depth determined as the coding depth may be determined.

In operation 1230, residual data and a motion vector encoded based on coding units, prediction units, or partitions having a tree structure may be encoded for each largest coding unit. Partition information including first partition information, a partition level, and the like for determining a prediction unit may be encoded together with information about a coded depth, a prediction mode, and a coding mode, and output as encoded information.

22 is a flowchart of a video decoding method using a variable partition for predictive encoding based on coding units having a tree structure, according to an embodiment of the present invention.

In step 1310, the bitstream for the encoded video is received and parsed. In operation 1320, information about a coded depth and an encoding mode is extracted for each coding unit according to coding units having a tree structure for each largest coding unit, from the parsed bitstream. Partition information according to an embodiment may be extracted from information about an encoding depth and an encoding mode. The partition information may include a first partition mode and a partition level, and may further include a second partition mode according to the first partition mode. Residual data and motion vectors encoded for each prediction unit may be extracted.

In operation 1330, for each largest coding unit, a coding unit having a tree structure is determined based on information about a coded depth and an encoding mode, a prediction unit and a partition are determined based on partition information, and prediction for the prediction unit and a partition is performed. Decryption can be performed. Based on the first partition information and the partition level of the partition information, the prediction unit in which the coding unit is divided and the shape, the splitting direction, and the size of the partition may be determined. For each prediction unit and partition, the residual data may be decoded using the prediction mode information and the motion vector, thereby reconstructing the picture.

According to an embodiment, the video encoding apparatus 100 using a variable partition based on a coding unit having a tree structure may have various sizes and various shapes according to a tree structure based on a variable size of a coding unit having a tree structure. And predictive encoding may be performed using prediction units (partitions) of various prediction modes, and the results may be compared to determine a prediction unit (partition) having the highest coding efficiency. Accordingly, prediction encoding is possible by considering an image characteristic in a coding unit that may change according to the size of the coding unit.

In addition, since the information about the element which determines the prediction unit used for the prediction encoding is encoded and transmitted, the video decoding apparatus 200 using the merging of the data units based on the coding unit having the tree structure according to an embodiment may correctly reconstruct. Can also be guaranteed.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium. The computer-readable recording medium may include a storage medium such as a magnetic storage medium (eg, a ROM, a floppy disk, a hard disk, etc.) and an optical reading medium (eg, a CD-ROM, a DVD, etc.).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

Claims (5)

Receiving a bitstream including size information of a maximum coding unit and split information of a coding unit;
Dividing a picture included in the video into a plurality of maximum coding units based on the size information of the maximum coding unit;
Recursively dividing a current maximum coding unit among the plurality of maximum coding units into one or more coding units based on the split information;
Determining at least one prediction unit in a current coding unit among the at least one coding unit based on partition information; And
Performing prediction on the at least one prediction unit,
The partition information indicates one of a symmetric partition type and an asymmetric partition type based on the size of the coding unit.
And wherein the asymmetric partition type includes an asymmetric partition obtained by dividing at least one of a height and a width of the coding unit into an asymmetrical ratio when the size of the coding unit is greater than or equal to a predetermined size. A receiver configured to receive a bitstream including size information of a maximum coding unit and split information of a coding unit;
The picture included in the video is divided into a plurality of maximum coding units based on the size information of the maximum coding unit, and the current maximum coding unit among the plurality of maximum coding units is recursively converted into one or more coding units based on the split information. And a decoder configured to determine at least one prediction unit from a current coding unit among the at least one coding unit based on partition information, and to perform prediction on the at least one prediction unit.
The partition information indicates one of a symmetric partition type and an asymmetric partition type based on the size of the coding unit.
And wherein the asymmetric partition type includes an asymmetric partition obtained by dividing at least one of a height and a width of the coding unit into an asymmetric ratio when the size of the coding unit is greater than or equal to a predetermined size. Dividing a picture included in the video into a plurality of maximum coding units based on the size information of the maximum coding unit;
Recursively dividing a current maximum coding unit among the plurality of maximum coding units into one or more coding units based on split information;
Determining at least one prediction unit in a current coding unit among the at least one coding unit based on partition information;
Performing prediction on the at least one prediction unit; And
Generating a bitstream including size information of the largest coding unit, split information of a coding unit, and partition information;
The partition information indicates one of a symmetric partition type and an asymmetric partition type based on the size of the coding unit.
The asymmetric partition type includes an asymmetric partition obtained by dividing at least one of a height and a width of the coding unit into an asymmetric ratio when the size of the coding unit is greater than or equal to a predetermined size. The picture included in the video is divided into a plurality of maximum coding units based on the size information of the maximum coding unit, and the current maximum coding unit among the plurality of maximum coding units is recursively divided into one or more coding units based on the split information. A splitter configured to determine at least one prediction unit from a current coding unit among the at least one coding unit based on partition information; And
An encoder which performs prediction on the at least one prediction unit and generates a bitstream including size information of the largest coding unit, split information of a coding unit, and partition information,
The partition information indicates one of a symmetric partition type and an asymmetric partition type based on the size of the coding unit.
And wherein the asymmetric partition type includes an asymmetric partition obtained by dividing at least one of a height and a width of the coding unit into an asymmetrical ratio when the size of the coding unit is greater than or equal to a predetermined size. A computer-readable recording medium including a bitstream, wherein the bitstream includes size information of a maximum coding unit, partition information of a coding unit, and partition information,
The picture included in the video is divided into a plurality of maximum coding units based on the size information of the maximum coding unit, and the current maximum coding unit among the plurality of maximum coding units is recursively into one or more coding units based on the split information. Divided into, and at least one prediction unit is determined from a current coding unit among the at least one coding unit, prediction is performed on the at least one prediction unit, and the partition information is determined by the coding unit. Represents one of a symmetric partition type and an asymmetric partition type based on the size of the asymmetric partition type. Partitioned asymmetric partitions Recording medium, characterized in that including.

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