KR20200008537A - Method for decoding partitioned block in video decoding and recording medium implementing the same - Google Patents

Abstract

The present invention relates to a method for encoding a division block in video encoding and a method for decoding the division block in the video decoding wherein an input screen is divided into encoding unit blocks, the encoding unit blocks are divided into sub blocks, and the encoding unit blocks or each sub block are encoded by selecting one of intra screen prediction encoding or inter screen prediction encoding. In addition, a decoding process can be performed through an inverse process of the encoding method. According to the present invention, flexibility of an encoding mode selection is increased in encoding the encoding unit block pixel value in the video encoding, thereby increasing encoding efficiency.

Description

Method for decoding partitioned block in video decoding and recording medium implementing the same

The present invention relates to a method and a method for decoding an input picture divided into blocks in video encoding and decoding by using intra- and inter-screen predictive encoding simultaneously, and in particular, to improve encoding efficiency. It is possible to improve the encoding efficiency by encoding block image signals using squared or non-squared transform according to the size of the split block. The present invention relates to a split block encoding and decoding method through intra prediction.

ISO / IEC 14496-10 (MPEG-4 Part 10 Advanced Video Coding) or H.264 and ISO / IEC 14496-10 comments, a technique for video compression encoding jointly standardized by ISO / IEC and ITU-T. The MPEG-4 Scalable Video Coding (3) specification, the SMPTE standard VC-1, and the Audio Video coding Standrad (AVS) specification have made great strides in video data compression efficiency.

There are many factors that can improve the video compression efficiency, but the existing video coding standards (MPEG-1 Video, MPEG-2 Video, MPEG-4 Part 2 Visual, H.261, H.263, etc.) Unlike dividing the size of the screen to be encoded into units of macroblocks (16 × 16 pixels) and then predictively encoding the macroblocks, the macroblocks are divided into 16 × 16, 16 × 8, 8 × 16, 8 × 8, 8 × 4, Further subdividing into 4x8 and 4x4 units, performing prediction coding on these lower blocks, and encoding a block that generates cost minimization in terms of rate-distortion cost is an optimal block mode.

In this way, motion estimation of fine motions or complex images can be performed more effectively, and compression efficiency can be greatly improved by greatly reducing residual signals generated.

FIG. 1 is a diagram illustrating a divided block type of a 16 × 16 macroblock unit block for encoding in a conventional H.264 | AVC encoder, and shows seven motion prediction block division types used in H.264.

As shown in FIG. 1, a block-based predictive encoding scheme generally encodes an input image by dividing the input image into 16 × 16 macroblock units. In particular, in ISO / IEC 14496-10 (MPEG-4 Advanced Video Coding) or H.264 standard, the macro block is divided into seven sub-blocks as shown in FIG. 1 to finally select and predict the block that minimizes the rate-distortion cost. Perform the encoding.

When intrablock coding is performed on the 16x16 macroblocks to be encoded, the intrablock coding is performed by intra-prediction encoding on a size of 16 × 16 pixels, or divided into four subblocks. Intra-prediction encoding of 8x8 blocks or intra-prediction encoding of 16 4x4 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 block modes. However, in low-resolution video encoding, high resolution (HD) or ultra high definition (UHD) video encoding is used. There is a problem. That is, in the case of a super macro block having a size of 32 × 32 or more that extends a 16 × 16 macroblock that is a coding unit block, the mode of all divided blocks in the super macroblock is changed to 16 × 16, 8 as in the conventional method. Applying the same intra picture prediction based on x8 or 4x4 blocks results in a loss of coding efficiency.

In other words, it is noted that in the conventional split block-based prediction coding method, all of the divided blocks are encoded only through intra prediction or inter prediction encoding. In other words, instead of applying both intra-block prediction and inter-prediction encoding, only one scheme is selected and applied. This may have a gain in coding efficiency in image or video compression of HD resolution or less due to the simplification of the syntax that expresses the block coding mode by applying only one of intra-screen or inter-screen coding, but the coding unit is super macroblock or more. In the case of a macro block, this may act as a factor of decreasing coding efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. In the video encoding of the present invention, intra- and inter-screen prediction encoding selection methods for sub-blocks of a divided block are extended to predict intra- and inter-screen prediction encoding. The purpose of the present invention is to provide a more efficient predictive encoding method by extending the 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 a divided block. .

Another object of the present invention is to provide a computer readable recording medium on 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 blocks into sub-blocks, and selects one of the sub-blocks from intra prediction encoding or inter prediction encoding. To encode it.

The method may further include selectively applying a variable transform kernel according to a block size with respect to the residual signal through the coding unit block and the lower block, quantizing the transform signal, and entropy encoding the result. have.

For the residual signal through the lower block, encoding may be performed by selectively applying one or more block boundary de-blocking filters according to a block size and an encoding type.

The coding unit block may have a size of N * N square, and the coding unit block may be divided into one or more squared or non-squared lower blocks of an arbitrary size.

In the case of encoding the lower block of the square or non-square using intra prediction encoding, one intra prediction encoding method may be selected from one or more intra prediction encoding methods to perform encoding.

When intra-prediction encoding or inter-screen prediction encoding is performed on the lower blocks of the square or non-square, entropy encoding may be performed by scanning a quantized transform coefficient selected according to the block size.

The square lower kernel may be transformed by applying a square transform kernel.

When converting the square lower kernel by applying a square transform kernel, a square transform kernel corresponding to a smaller or equal number of pixels may be applied by comparing the horizontal pixel number and the vertical pixel number of the lower square block.

A non-square transform kernel may be applied to the non-square lower blocks.

When the non-square transform kernel is applied to the non-square lower block, the non-square transform kernel corresponding to the same or smaller pixel number may be applied by comparing the number of horizontal pixels and the vertical pixel of the non-square lower block. Can be.

According to another embodiment of the present invention, a method of encoding a split block in video encoding includes (a) inputting a screen to be encoded, (b) dividing an input bottom surface into coding unit blocks, and (c) input angles. Dividing a coding unit block into lower blocks, (d) performing intra-prediction encoding and inter-screen prediction encoding on the coding unit block and its lower blocks, and selecting one of the block types; and (e The method may include performing intra prediction encoding and / or inter prediction encoding on a lower block including a coding unit block by using the prediction result of the block type.

In the split block encoding method according to another embodiment of the present invention, (a ') inputting a screen to be encoded, (b') splitting the input screen into coding unit blocks, and (c ') Determining whether the current input screen is to perform inter-prediction encoding; or (d ') initializing the order of the lower blocks of the coding unit blocks encoded in the input screen when the current input screen is inter-screen prediction. (e ') selecting a block mode of a coding unit block to be encoded, (f') determining whether to perform both intra-picture and inter-screen prediction coding for the selected block mode, and (g ') Performing both intra and inter prediction encoding for the selected block mode when performing both intra and inter prediction encoding for the block mode, (h ') in the step (g') Storing the side encoding result and the rate-distortion cost value, and (i ') if the selected block mode is the final mode, comparing the rate-distortion cost for each block mode to select and encode the final block mode for the coding unit block Determining (j ') whether the current coding unit block is the last block in the current input screen; and (k') if the current coding unit block is the last block in the current input screen, whether the current input screen is the final screen. And determining (a ') to (j') repeatedly until the current input screen becomes a final screen.

After step (c '), if the current input screen is not inter prediction, the method may further include performing intra prediction encoding.

After the step (f '), the method may further include performing inter-prediction encoding on the selected block mode when both intra-screen and inter-screen prediction encoding are not performed on the selected block mode.

After the step (g '), when performing inter prediction encoding on the selected block mode, a residual signal is obtained through motion prediction and compensation, and the selected block is transformed using the residual signal, and then quantized. The method may further include entropy encoding the result.

After performing step (g '), when performing intra prediction encoding on the selected block mode, the residual signal is obtained through intra prediction encoding, the selected block is transformed using the residual signal, and quantized. The method may further include entropy encoding the result.

When converting the block selected using the residual signal, the method may further include performing a transform by selectively applying a transform kernel according to the size of the block.

According to another aspect of the present invention, there is provided a video decoding method using a split block encoding method, comprising: (A) inputting a bitstream to be decoded, (B) determining whether an input bitstream is inter prediction, (C) ) Performing intra picture prediction encoding if the input bitstream is intra picture prediction, (D) analyzing a slice if the input bit stream is inter picture prediction, (E) analyzing a unit coded block within the slice (F) decoding the subdivided block coding mode of the unit coding block, (G) analyzing whether the subdivided coding block is an inter prediction coding block, (H) the subdivided coding block is inter-screen Performing inter-prediction decoding in case of prediction, (I) performing intra-prediction decoding in case the sub-divided coding block is intra prediction, (J) the Splitting the split block decoding result into unit decoding block pixels, (K) forming the decoding unit block result into slice pixels, and (K) splitting the slice pixel composition result into a screen Intra-block prediction and / or inter-screen prediction decoding may be performed.

In the step (C), if the unit coding block is a supermacroblock of 16x16 macroblock size or more, the method may further include performing intra prediction prediction decoding by decoding a subdivision block encoding mode corresponding to the corresponding size.

In the step (C), the method may further include performing intra prediction prediction decoding by applying a de-blocking filter corresponding to the size of the subdivided block.

In the step (C), the method may further include performing intra prediction prediction decoding by applying a de-blocking filter according to the size of the subdivided block.

In the step (F), if the unit coding block is a super macro block of 16x16 macroblock size or more, the method may further include decoding a subdivision block encoding mode corresponding to the size.

In the step (H), the method may further include performing intra prediction prediction decoding by decoding the encoded quantized transform coefficients by applying a square or non-square variable kernel corresponding to the size of the subdivided block.

In the step (H), the method may further include performing intra prediction prediction decoding by decoding the encoded quantization transform coefficients by applying an inverse quantization method according to the size of the subdivided block and the decoding mode condition of the neighboring decoding block. .

In the step (H), the method may further include performing inter prediction prediction decoding by applying a de-blocking filter corresponding to the size of the lower block.

In another embodiment of the present invention, there is provided a computer readable recording medium having recorded thereon a program which can be executed by a computer.

According to the present invention, in encoding a coding unit block pixel value in video encoding, subblocks obtained by applying one or more intra-picture prediction and inter-picture prediction coding to the divided subblock or the subdivided blocks are encoded. It is possible to be encoded in the intra or inter prediction encoding mode so that the coding unit block or sub-divided block is predictively encoded by using both intra and inter prediction, thereby increasing the flexibility of encoding mode selection and increasing the coding efficiency. There is.

In the present invention, in the partition block-based prediction encoding, each partitioned block can apply both intra prediction and inter prediction to sub-split sub-blocks, and selectively transforms them according to the size of the partitioned block. Encoding may be performed by applying a variable block-size transform kernel size, thereby greatly improving encoding efficiency.

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

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In describing the present invention, when 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 picture 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 a block division type of 16x16 pixel unit macroblock size or larger applied in an embodiment of the present invention.

 As shown in FIG. 2, the super macro block is divided into sub-blocks, and an intra-picture or inter-screen prediction encoding process is performed on each divided block so that the final macro mode is mixed with the intra-picture or inter-screen prediction coding mode. Encoding is performed so that the encoding efficiency of an image can be increased very effectively. In actual encoding, as shown in Equation 1, a block mode that minimizes the rate-distortion cost may be selected and encoded.

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

Is a Lagrangian multiplier that is mode dependent, and MODE represents a split block mode type.

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

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

Where X represents an NxN input video signal matrix, A represents an NxN square transform kernel matrix, and Y represents a transform coefficient matrix. If the divided lower block is a non-square block, the transform 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. Represent the coefficient matrix.

In the exemplary embodiment of the present invention, when the 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 pixel number of the horizontal or vertical pixel number 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 order of the screen 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 screen i performs inter prediction encoding (S104). If the current screen i is not inter prediction, intra prediction encoding is performed (S105). Otherwise, if the current screen i is inter prediction, a coding unit encoded in one screen i. The order of the block j is initialized (j = 0) (S106).

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

It is checked whether intra-picture and inter-screen prediction are performed in the lower block mode encoded in the coding unit block (S110). In case of performing inter-screen and intra-screen prediction, intra- and inter-screen coding is performed (S111), otherwise, only inter-screen prediction coding is performed (S112). Then, the predictive encoding result and the rate-distortion cost value which are the encoding performance result 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, the optimal split block mode is determined and the corresponding encoding result is finally selected (S115).

In operation S116, it is determined whether the current coding unit block j is the last block in the current screen i. If the current coding unit block j is not the last block, the next coding unit block is input and the steps S107 to S115 are repeated.

If the coding unit block j is the last block in the current screen i, it is determined whether the current screen i is the last screen in step S116 (S117). If the current screen i is the last screen, the algorithm is terminated. Otherwise, the algorithm returns to step S102, the next screen is input, and the steps S102 to S116 are repeated.

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

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

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

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

Next, after analyzing the unit coded block information (S208), the order of the lower divided blocks in the unit coded block is initialized (m = 0) (S209). Thereafter, the coding mode of the lower partition block in the unit coding block is decoded (S210). After checking whether the lower split block is an inter prediction encoding block (S211), inter prediction encoding is performed if the inter prediction encoding block is performed (S213), and intra prediction encoding is performed if the mode is an intra prediction encoding block (S211). S212).

Thereafter, the lower partition block pixel value is restored using the lower partition block decoding result (S214). Thereafter, after checking whether the current subdivision block (m) is the last block (S215), if it is the last subdivision block, a unit decoding block pixel value is configured (S216); otherwise, step S210 to decode the next subdivision block. The method returns to step S210 to step S214.

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

In video encoding according to an embodiment of the present invention, after dividing an input image into coding unit blocks, dividing the coding unit blocks into lower blocks, and encoding each subdividing block, one or more of intra prediction and inter screen prediction. Perform encoding by using.

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

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

As another embodiment of the present invention, the subdivided block encoding method in the video encoding described above may be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored.

For example, a computer-readable recording medium may be a ROM, a RAM, a CD-ROM, a magnetic tape, a hard disk, a floppy disk, a removable storage device, a nonvolatile memory (Flash memory). Optical data storage, and the like, and also implemented in the form of a carrier wave (eg, transmission over the Internet).

The computer readable recording medium can also be distributed over computer systems connected over a computer network, stored and executed as distributed readable code.

Although a description has been given of a preferred embodiment of the intra prediction encoding method and / or the inter prediction encoding method in the video encoding according to the present invention, and the decoding method thereof, the embodiments are exemplary. It is not limited. Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the invention and the scope of rights set forth in the appended claims.

Claims (1)

And a coding unit block within a current slice is divided into four first subblocks.

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