KR20210064133A - Method for decoding partitioned block in video decoding - Google Patents

Abstract

The present invention provides a method for decoding a partitioned block in video decoding. An objective of the present invention is to provide an effective prediction encoding method. According to one embodiment of the present invention, the method for decoding a partitioned block in video decoding comprises: a step of receiving a sequence of encoded video data, wherein the sequence of the video data includes coding unit blocks, the coding unit blocks are partitioned into first sub-coding units, and at least some of the first sub-coding units are partitioned into second sub-coding units; a step of obtaining an encoding mode for a sub-coding unit selected among the partitioned first sub-coding units or the partitioned second sub-coding units; a step of performing intra prediction or inter prediction on the selected sub-coding unit based on the obtained encoding mode; and a step of transforming residual data of the selected sub-coding unit, wherein variable-size transform kernels are selectively applied to the selected sub-coding unit, and the variable-size transform kernels are based on the size of the selected sub-coding unit.

Description

Method for decoding partitioned block in video decoding {Method for decoding partitioned block in video decoding}

The present invention relates to a method of dividing an input picture into blocks in video encoding and decoding and encoding and decoding the divided blocks using intra-picture and inter-picture prediction coding at the same time, in particular, improving encoding efficiency According to the size of the divided block, by encoding a block image signal using a square transform or a non-squared transform, the coding efficiency can be further improved by encoding between screens and screens. It relates to a split block encoding and decoding method through my prediction.

ISO/IEC 14496-10 (MPEG-4 Part 10 Advanced Video Coding) or H.264 and ISO/IEC 14496-10 Amendment, a technology for video compression coding jointly standardized by ISO/IEC and ITU-T 3 (MPEG-4 Scalable Video Coding) standard, SMPTE standard VC-1, and other audio video coding standard (Audio Video coding Standard, AVS) standards have made great strides in video data compression efficiency.

There may be various factors for improving video compression efficiency, but in particular, existing video encoding standards (MPEG-1 Video, MPEG-2 Video, MPEG-4 Part 2 Visual, H.261, H.263, etc.) Unlike predictive encoding after dividing the size of a screen to be encoded into macroblocks (16×16 pixels), macroblocks are divided into 16×16, 16×8, 8×16, 8×8, 8×4, It is further subdivided into 4×8 and 4×4 units, and predictive encoding is performed on these sub-blocks, and a block that generates cost minimization in terms of rate-distortion cost is encoded as an optimal block mode.

In this way, it is possible to more effectively perform a motion prediction of a fine motion or a complex image, and greatly improve the compression efficiency by greatly reducing the generated residual signal.

FIG. 1 is a diagram illustrating a split block type of a 16×16 macroblock unit block for encoding in a conventional H.264|AVC encoder. Seven types of motion prediction block splitting types used in H.264 are shown.

As shown in FIG. 1 , in a conventional block-based prediction encoding method, an input image is divided into 16×16 macroblock units and encoded. In particular, in the ISO/IEC 14496-10 (MPEG-4 Advanced Video Coding) or H.264 standard, a macroblock is divided into 7 sub-blocks as shown in FIG. 1, and a block that minimizes rate-distortion cost is finally selected and predicted perform encoding.

When intra-encoding is performed on sub-blocks divided for a 16×16 macroblock to be coded, intra-prediction coding is performed on the macroblock to a size of one 16×16 pixel unit, or it is divided into sub-blocks and divided into four sub-blocks. Intra prediction encoding of 8×8 blocks or intra prediction encoding of 16 4×4 blocks is performed.

In general, in low-resolution video encoding, such an intra prediction encoding technique has encoding efficiency in terms of reducing the number of cases of multiple block modes, but is not suitable for high-definition (HD) or ultra-high-definition (UHD) video encoding. there is a problem with That is, in the case of a super macroblock having a size of 32×32 or larger by extending a 16×16 macroblock, which is a coding unit block, the mode of all the blocks divided in the super macroblock is set to 16×16, 8 as in the conventional method. If the same intra prediction based on x8 or 4x4 blocks is applied, the encoding efficiency is lowered.

In other words, what is noteworthy in the conventional split block-based prediction coding method is that all the divided blocks are encoded only through intra-picture or inter-picture prediction coding. That is, neither intra-block prediction encoding nor inter prediction encoding is applied, but only one method is selected and applied. In this case, there may be a gain in encoding efficiency in image or video compression of HD resolution or less due to the simplification of the syntax expressing the block encoding mode by applying only one of the intra-picture or inter-picture encoding, but the coding unit is a super block of macroblock or larger. In the case of a macroblock, it may act as a factor of lowering encoding efficiency.

The present invention has been devised to solve the above problems, and it is possible to extend the intra- or inter-prediction encoding selection method for sub-divided blocks of a block divided during video encoding of the present invention to perform intra- and inter-prediction encoding. The purpose of this is to provide a more effective predictive encoding method by extending all modes to be selectable and performing encoding by selectively applying a square or non-square transform kernel according to the block size to the residual signal after motion compensation of the divided block. .

Another object of the present invention is to provide a computer-readable recording medium in which the method is implemented.

In order to achieve the above object, the present invention divides an input picture into coding unit blocks, divides the coding unit block into sub-blocks, and selects one of intra prediction coding or inter prediction coding for each sub-divided block. to encode

One embodiment includes receiving a sequence of encoded video data, wherein the sequence of video data includes coding unit blocks; The coding unit blocks are divided into first sub coding units, at least some of the first sub coding units are divided into the second sub coding unit, and the divided first sub coding units or the second sub coding units obtaining an encoding mode for a selected sub coding unit among the coding units; performing intra prediction or inter prediction on the selected sub coding unit based on the obtained encoding mode; and performing transform on residual data of the selected sub coding unit, wherein transform kernels of variable size are selectively applied to the selected sub coding uniting, wherein the transform kernels of variable size are the selected sub coding uniting units. It provides a method of decoding a divided block in video decoding, including; based on the size of .

According to the present invention, in encoding a coding unit block pixel value in video encoding, the sub-blocks divided by applying one or more intra-prediction encoding and inter-prediction encoding to the divided sub-block or sub-divided blocks are applied to encode the sub-blocks into a picture. Effect of increasing encoding efficiency by increasing flexibility in encoding mode selection by enabling encoding in the intra- or inter-prediction encoding mode so that the coding unit block or its subdivision blocks are predictive-encoded using both intra- and inter-prediction there is

In addition, in the present invention, in split block-based prediction coding, both intra prediction and inter prediction can be applied to sub-divided blocks below each split block, and variable transformation is selectively performed according to the size of the split block. Encoding is performed by applying a size of a variable block-size transform kernel, thereby greatly improving encoding efficiency.

1 is a diagram illustrating a split block type of a 16×16 macroblock unit block for encoding in a conventional H.264|AVC encoder.
2 is a diagram illustrating super macroblock unit blocks and split block types for intra- or inter-picture prediction encoding in an encoder according to an embodiment of the present invention;
3 is a flowchart illustrating a split block encoding method in video encoding according to an embodiment of the present invention.
4 is a flowchart illustrating a method of decoding a bitstream encoded by the video split block method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, it should be noted that in adding reference numerals to the components of each drawing, the same components are provided with the same reference numerals as much as possible even though they are indicated on different drawings. And, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

2 is a diagram illustrating a super macroblock unit block and a split block type for intra- or inter-picture prediction encoding in an encoder according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a super macro block and block division type having a macroblock size of 16×16 pixels or more applied in an embodiment of the present invention.

As shown in FIG. 2 , the super macro block is divided into sub-blocks, and intra or inter prediction encoding is performed on each divided block, so that the final encoding mode of the super macro block is a mixture of intra or inter prediction encoding modes. It is possible to very effectively increase the encoding efficiency of an image by allowing the encoding to be performed. In actual encoding, as in Equation 1, a block mode that minimizes rate-distortion cost can be selected and encoded.

는 모드에 의존적인 라그랑지안 승수이고, MODE는 분할 블록 모드 타입을 나타낸다.where J _MODE is a rate-distortion function for the block encoding mode, s is the original block pixel input to be encoded, r is the reference image pixel input, QP is the quantization parameter,

is a mode-dependent Lagrangian multiplier, and MODE indicates the split block mode type.

In addition, when transform coding is applied to the residual signal of a super macroblock with an increased size, a square transform kernel of 16x16 or larger size larger than the existing 4x4 and 8x8, or 16x8 for non-square transform, or Encoding efficiency can be increased by selectively applying an 8x16 or larger non-square transform kernel according to the size of the split block.

When a square transform kernel having a size of 16x16 or larger is applied to the super macro block, it can be calculated as in Equation (2).

Here, X denotes an NxN input image signal matrix, A denotes an NxN square transform kernel matrix, and Y denotes a transform coefficient matrix. If the divided sub-block is a non-square block, transformation is performed as in Equation (3).

Here, when the input image signal X is an Mx(M/2) matrix, A ₁ represents an MxM square transform kernel matrix, A ₂ represents a (M/2)x(M/2) square transform kernel matrix, and Y represents a transform Represents the coefficient matrix.

In an embodiment of the present invention, when a square or non-square kernel transform is applied, it is preferable to perform transform encoding by applying a kernel having the same or smaller size compared to the smaller number of horizontal or vertical pixels of the divided block. .

3 is a flowchart illustrating a split block encoding method in video encoding according to an embodiment of the present invention.

Referring to FIG. 3 , first, the sequence of pictures (i) for encoding is initialized (i=0) (S101). Then, the screen (i) is input in order for encoding (S102).

Next, the input screen i is divided into coding unit blocks (S103). In an embodiment of the present invention, the coding unit block may be a macro block or a super macro block.

Next, it is checked whether the current picture i will perform inter prediction encoding (S104). If the current picture (i) is not inter prediction, intra prediction encoding is performed (S105), otherwise, if the current picture (i) is inter prediction, coding units encoded within one picture (i) The order of the block j is initialized (j=0) (S106).

Thereafter, the unit block j to be encoded is divided into sub-blocks (S107). And the order of the lower block mode (k) is initialized (k = 0) (S108). One block mode is selected from among the lower block modes (k) (S109).

It is checked whether intra- and inter-prediction is performed on a sub-block mode encoded in a coding unit block (S110). In the case of performing inter prediction and intra prediction, intra and inter prediction encoding is performed (S111). Otherwise, only inter prediction encoding is performed (S112). Then, the prediction encoding result and the rate-distortion cost value that are the encoding performance results are stored (S113).

It is checked whether the lower block mode (k) is the final block mode (S114). If the lower block mode (k) is not the final block mode, steps S109 to S113 are repeated for the next block mode. On the other hand, if the lower block mode (k) is the final block mode, an optimal split block mode is determined and a corresponding encoding result is finally selected ( S115 ).

Then, it is determined whether the current coding unit block j is the last block in the current picture i (S116). If the current coding unit block j is not the final block, steps S107 to S115 are repeated by inputting the next coding unit block.

If the coding unit block j is the last block in the current picture i in step S116, it is checked whether the current picture i is the final picture (S117). If the current screen (i) is the final screen, the algorithm is terminated, otherwise it returns to step S102 to input the next screen and repeat steps S102 to S116.

4 is a flowchart illustrating a method of decoding a bitstream encoded by the video split block method according to an embodiment of the present invention.

Referring to FIG. 4 , first, the order of the screen (i) for decoding is initialized (i=0) (S201). Then, the screen encoding bitstream (i) is input in order for decoding (S202).

Next, it is checked whether the input picture bitstream (i) is inter prediction encoding (S203). If the current picture bitstream (i) is not inter prediction encoding, intra prediction decoding is performed (S207). Otherwise, if the current input picture bitstream (i) is inter prediction encoding, one picture ( The order of the slices j to be decoded in i) is initialized (j=0) (S204).

Next, slice information is analyzed for the input picture bitstream (S205). The order of the unit decoding blocks j decoded in each slice within one picture i is initialized (k=0) (S206). In an embodiment of the present invention, the decoding unit block may be a macro block or a super macro block.

Next, after each unit coding block information is analyzed (S208), the order of the sub-divided blocks in the unit coding block is initialized (m=0) (S209). Thereafter, the coding mode of the sub-divided block within the unit coding block is decoded ( S210 ). After confirming whether the sub-divided block is an inter prediction coding block (S211), inter prediction decoding is performed if it is an inter prediction coding block (S213), and if it is an intra prediction coding block, intra prediction coding is performed (S213). S212).

Thereafter, the pixel value of the lower divided block is restored by using the decoding result of the lower divided block (S214). Thereafter, after checking whether the current subdivided block m is the final block (S215), if it is the last subdivided block, a unit decoding block pixel value is configured (S216), otherwise step S210 for decoding the next subdivided block to perform steps S210 to S214.

Thereafter, after checking whether the current unit coding block (k) is the final unit coding block (S217), if it is the final unit coding block, a slice pixel is configured (S218), otherwise it returns to step S208 and performs steps S208 to S216 do. Thereafter, after checking whether the current slice j is the final slice (S219), if it is the final slice, screen pixels are configured (S220), otherwise, steps S205 to S218 are performed. Thereafter, after determining whether the current screen i is the final screen (S221), if it is the final screen, it ends. Otherwise, the process returns to step S202 to input the next screen bitstream, and steps S202 to S220 are performed.

In video encoding according to an embodiment of the present invention, at least one of intra prediction and inter prediction in encoding each subdivision block after dividing an input image into coding unit blocks and dividing the coding unit blocks into sub-blocks again is optionally used to perform encoding.

In this way, the coding mode of the coding unit block can be encoded by mixing the inter prediction and the intra prediction sub-division block mode, and at the same time, the coding efficiency can be improved by selectively applying the variable kernel transform according to the split block.

In addition, in video decoding according to an embodiment of the present invention, a compressed bitstream having improved encoding efficiency may be decoded by performing a reverse process of the encoding process.

As another embodiment of the present invention, it is possible to implement the sub-division block encoding method in video encoding described above as computer-readable codes on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices that store data that can be read by a computer system.

For example, computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, removable storage device, and non-volatile memory (Flash Memory). , an optical data storage device, and the like, and also includes those implemented in the form of a carrier wave (eg, transmission through the Internet).

In addition, the computer-readable recording medium may be distributed in computer systems connected through a computer communication network, and stored and executed as readable codes in a distributed manner.

Although preferred embodiments of the intra prediction encoding method and/or the inter prediction encoding method in the video encoding according to the present invention have been described above, and the decoding method, which is a reverse process thereof, these embodiments are exemplary only. It is not limited. Those of ordinary skill in the art to which the present invention pertains will understand that various changes and modifications can be made without departing from the spirit of the present invention and the scope of the appended claims.

Claims (1)

receiving a sequence of encoded video data;
wherein the sequence of video data includes coding unit blocks;
The coding unit blocks are divided into first sub coding units,
At least some of the first sub-coding units are divided into the second sub-coding units,
obtaining an encoding mode for a selected one of the divided first sub-coding units or the second sub-coding units;
performing intra prediction or inter prediction on the selected sub coding unit based on the obtained encoding mode; and
performing transformation on residual data of the selected sub coding unit;
Here, by selectively applying transform kernels of variable size to the selected sub-coding uniting,
wherein the variable-sized transform kernels are based on the size of the selected sub-coding unit; including,
A split block decoding method in video decoding.

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