JP2022008371A - Dynamic image encoding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic image encoding device which improves encoding efficiency without increasing throughput.

SOLUTION: A dynamic image encoding device comprises: a block dividing section which (i) divides a target picture into a plurality of encoding units and (ii) divides each of the plurality of encoding units into at least one prediction unit; and a residual encoding section which generates a residual component by operating a differential between a prediction image which is generated for each prediction unit, and the target picture. Only in a case where a first size of a first encoding unit in the plurality of encoding units is 2 N×2 N, a second size of the prediction unit in the first encoding unit is any one of 2 N×2 N, 2 N×N and N×2 N at all times and in a case where the first size of the first encoding unit in the plurality of encoding units is not 2 N×2 N, the second size of the prediction unit in the first encoding unit is any one of 2 N×2 N, 2 N×N, N×2 N and N×N.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present disclosure relates to a moving image coding device that divides an input image into blocks and encodes the input image, and a moving image coding method.

In recent years, with the development of multimedia applications, it has become common to handle information in all media such as images, sounds, and texts in a unified manner. In addition, since digitized images have a huge amount of data, image information compression technology is indispensable for storage and transmission. On the other hand, standardization of compression technology is also important for interoperability of compressed image data. For example, as a standard for moving image compression technology, H.I. 261 and H. 263, H. 264, ISO / IEC (International Organization for Standardization) MPEG-1, MPEG-3, MPEG-4, MPEG-4 AVC and the like. At present, a standardization activity of a next-generation moving image coding method called HEVC (High Efficiency Video Coding) is underway in collaboration with ITU-T and ISO / IEC.

In such video coding, each picture to be coded is divided into blocks of coding units, and the amount of information is compressed by reducing redundancy in the time direction and the spatial direction for each block. In in-screen prediction coding for the purpose of reducing spatial redundancy, a prediction image is generated from the pixel information of the peripheral coded blocks, and the difference image between the obtained prediction image and the block to be encoded is displayed. get. In interscreen predictive coding for the purpose of reducing temporal redundancy, motion detection and predictive images are generated in block units by referring to pictures that have already been coded forward or backward. The difference image between the predicted image and the block to be encoded is acquired. The amount of information is compressed by performing orthogonal transformation processing such as discrete cosine transform and quantization processing on these obtained difference images and generating a code string using variable length coding and arithmetic coding.

FIG. 1 is a conceptual diagram for explaining a combination of block sizes defined in the HEVC standard. In HEVC (Non-Patent Document 1), as a coding unit (hereinafter referred to as “Colding Unit: CU”), as shown in FIG. 1, 64 × 64 pixels, 32 × 32 pixels, 16 × 16 pixels, 8 × 8 Any size can be selected and used from the four types of block sizes of pixels.

Further, it is a unit obtained by dividing the CU, and as a prediction unit (hereinafter referred to as "Prescription Unit: PU") for generating a prediction image in the in-screen prediction coding and the inter-screen prediction coding, for example, the CU size is 32x32 pixels. In this case, as shown in FIG. 1, any size can be selected and used from eight types of block sizes such as 32 × 32 pixels, 16 × 32 pixels, and 16 × 16 pixels. For example, high coding efficiency is realized by using a small block size for an image having a complicated movement of an imaged object and using a large block size for an image having a simple motion of an imaged object.

Further, the unit is a unit obtained by further dividing the CU, and as the above-mentioned orthogonal transformation unit and the orthogonal transformation unit (hereinafter referred to as “Transform Unit: TU”) for the orthogonal transformation processing and the quantization processing, for example, the CU size is 32x32 pixels as shown in FIG. In this case, any size can be selected and used from four types of block sizes of 32 × 32 pixels, 16 × 16 pixels, 8 × 8 pixels, and 4 × 4 pixels. For example, high coding efficiency is realized by using a small block size for an image having different characteristics in a fine range and using a large block size for an image having similar characteristics in a wide range.

ITU-T H. 265: High efficiency video coding (04/2013)

In HEVC, four types of block sizes can be selected as CU. However, as the number of blocks of CU is increased in the coding process, the amount of code of the header information in the CU layer increases. As a result, the coding efficiency may deteriorate.

The present disclosure has been made in view of the above problems, and provides a moving image coding apparatus that suppresses the coding amount of the header information of the CU layer and the PU layer and improves the coding efficiency without increasing the processing amount. do.

The moving image coding device according to the present disclosure is a moving image coding device that encodes a target picture to generate a code sequence, and in operation, (i) divides the target picture into a plurality of coding units. , (Ii) By calculating the difference between the block division unit that divides the plurality of coding units into at least one prediction unit, the prediction image generated for each prediction unit, and the target picture in the operation. A prediction unit in the first coding unit is provided with a residual coding unit for generating a residual component, and only when the first size of the first coding unit of the plurality of coding units is 2N × 2N. The second size of is always one of 2N × 2N, 2N × N and N × 2N, and if the first size of the first coding unit of the plurality of coding units is not 2N × 2N. The second size of the prediction unit in the first coding unit is one of 2N × 2N, 2N × N, N × 2N and N × N.

From the above, the moving image coding apparatus in the present invention can suppress the coding amount of the header information of the CU layer and the PU layer, and can improve the coding efficiency without increasing the processing amount. ..

It should be noted that the present disclosure can not only be realized as such a moving image coding device, but also can realize the same processing as each means included in such a moving image coding device as a program or an integrated circuit. You can also.

It is a conceptual diagram for demonstrating the combination of each block size defined in the HEVC standard. It is a block diagram which shows the structure of the moving image coding apparatus 100 which concerns on Embodiment 1. FIG. It is a conceptual diagram for demonstrating the combination of each block size which concerns on Embodiment 1. FIG. It is a flowchart which shows the integration determination process which concerns on Embodiment 1. It is an image diagram which shows the integration determination process which concerns on Embodiment 1. It is an image diagram which shows the integration determination process which concerns on Embodiment 1. It is a conceptual diagram for demonstrating the combination of each block size which appears by performing the integration determination process which concerns on Embodiment 1. FIG. It is a flowchart which shows the integration determination process which concerns on Embodiment 2. It is an image diagram which shows the integration determination process which concerns on Embodiment 2. It is an image diagram which shows the integration determination process which concerns on Embodiment 2. It is a conceptual diagram for demonstrating the condition of the integration determination processing which concerns on Embodiment 2. It is a conceptual diagram for demonstrating the combination of each block size which appears by performing the integration determination process which concerns on Embodiment 2. It is a flowchart which shows the integration determination process which concerns on Embodiment 3. It is an image diagram which shows the integration determination process which concerns on Embodiment 3. FIG. It is an image diagram which shows the integration determination process which concerns on Embodiment 3. FIG. It is an image diagram which shows the integration determination process which concerns on Embodiment 3. FIG. It is a conceptual diagram for demonstrating the combination of each block size which appears by performing the integration determination process which concerns on Embodiment 3. FIG.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters and duplicate explanations for substantially the same configuration may be omitted. This is to avoid unnecessary redundancy of the following description and to facilitate the understanding of those skilled in the art.

It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
The moving image coding device 100 according to the first embodiment is realized by, for example, a microprocessor mounted on a video camera, a digital camera, a video recorder, a mobile phone, a mobile information terminal, a personal computer, or the like. The moving image coding device 100 performs a moving image data coding process in accordance with HEVC, which is a moving image compression standard. The moving image coding device 100 according to the present disclosure integrates a plurality of CUs into one CU based on the coding information of the CU (Heading Unit) and the PU (Prediction Unit), and 1 for the integrated CU. Add one header information. As a result, it is possible to suppress the code amount of the header information of the CU layer and the PU layer, and it is possible to improve the coding efficiency without increasing the processing amount.

Hereinafter, the configuration and operation of the moving image coding apparatus 100 according to the first embodiment will be described with reference to the drawings.

[1-1. Configuration of video coding device]
The configuration of the moving image coding device 100 will be described. FIG. 2 is a block diagram showing the configuration of the moving image coding device 100 according to the first embodiment.

As shown in FIG. 2, the moving image coding device 100 includes a picture memory 101, a basic block dividing unit 102, a basic block unit processing loop unit 111, an integration determination unit 107, and a code string generation unit 108. ing. Then, the moving image coding device 100 serves as a basic block unit processing loop unit 111, which includes a prediction residual coding unit 103, a prediction residual decoding unit 104, a picture buffer 105, a prediction processing unit 106, and a difference calculation unit. It is provided with 109 and an addition calculation unit 110. With this configuration, the moving image coding apparatus 100 divides an image input in picture units into basic blocks, then performs coding processing in units of the divided basic blocks, and outputs a code string.

Subsequently, details of each part constituting the moving image coding device 100 will be described.

The picture memory 101 inputs image signals in picture units in the order in which they are displayed on the display device. The picture memory 101 rearranges and stores the input image signals in the order of encoding. When the picture memory 101 receives a read command from the basic block division unit 102, the picture memory 101 outputs a coded target picture to be coded, which is an input image signal related to the read command, to the basic block division unit 102.

The basic block dividing unit 102 as a dividing unit divides and outputs the pictures to be coded sequentially input from the picture memory 101 for each coding unit. The basic block division unit 102 divides into basic blocks, which are basic units of processing in the basic block unit processing loop unit 111. The moving image coding device 100 limits the size of the basic block to 64 × 64 pixels defined by HEVC and 16 × 16 pixels smaller than 32 × 32 pixels. A basic block contains one or more CUs, which are coding units defined in the HEVC standard. FIG. 3 is a conceptual diagram for explaining a combination of block sizes according to the first embodiment. As shown in the column of "basic CU size" in FIG. 3, the basic CU size can take a size of 16 x 16 pixels and a size of 8 x 8 pixels for a basic block of 16 x 16 pixels. One CU having a size of 16 × 16 pixels is included in a basic block of 16 × 16 pixels. Four CUs with a size of 8 × 8 pixels are included for a basic block of 16 × 16 pixels. Hereinafter, these CUs included in the basic block will be referred to as "basic CUs". The basic block dividing unit 102 divides the input picture into basic blocks and selects the size of the basic CU. Generally, the basic block dividing unit 102 selects a small-sized basic CU when the pixel configuration of the input picture is complicated, while the basic block dividing unit 102 selects a large-sized basic CU when the pixel configuration of the input picture is simple. Select. It should be noted that some of the basic CUs shown in the example of FIG. 3 are not used, or the basic CUs that are not shown in the example of FIG. 3 and are smaller than the basic block are used. However, the same explanation is possible.

The basic block dividing unit 102 sequentially outputs the pictures divided into basic blocks (the size of the basic CU has been selected) to the prediction processing unit 106 and the difference calculation unit 109.

The prediction processing unit 106 performs prediction processing using either in-screen prediction or inter-screen prediction for each basic block based on the pictures divided into basic blocks sequentially input from the basic block division unit 102. The prediction processing unit 106 performs prediction processing for each PU (hereinafter, referred to as “basic PU”) which is a prediction unit obtained by further dividing the basic CU. Specifically, as shown in the column of "basic PU size" in FIG. 3, when the size of the basic CU is 16 × 16 pixels, one basic PU of 16 × 16 pixels and two of 16 × 8 pixels. It is divided into a basic PU or a basic PU of two basic PUs of 8 × 16 pixels. However, the basic PU sizes of 16 × 8 pixels and 8 × 16 pixels are used only when interscreen prediction is selected. On the other hand, when the size of the basic CU is 8 × 8 pixels, one basic PU of 8 × 8 pixels, two basic PUs of 8 × 4 pixels, two basic PUs of 4 × 8 pixels, or 4 × 4 pixels. It is divided into one of the four basic PUs of. However, the basic PU sizes of 8 × 4 pixels and 4 × 8 pixels are used only when interscreen prediction is selected. The basic PU size of 4x4 pixels is used only when in-screen prediction is selected. Generally, the prediction processing unit 106 selects a basic PU having a small size when the pixel configuration of the input basic CU is complicated, while the prediction processing unit 106 selects a basic PU having a large size when the pixel configuration of the input basic CU is simple. Select PU. It should be noted that some of the basic PUs shown in the example of FIG. 3 are not used, or a basic PU having a size not shown in the example of FIG. 3 and a size smaller than the basic CU is used. However, the same explanation is possible.

When the in-screen prediction is used, the prediction processing unit 106 predicts the blocks in the picture to be encoded by using the reconstructed image signals of the peripheral blocks already encoded in the same picture. The reconstructed image signal is a signal generated by the addition calculation unit 110, which will be described later. The prediction processing unit 106 selects one of the in-screen prediction modes (in-screen prediction modes) that generates a prediction image having the highest degree of similarity to the pixel configuration of the block to be encoded. Prediction processing is performed by doing.

On the other hand, when interscreen prediction is used, the prediction processing unit 106 performs prediction processing using the reconstructed image signal of another already encoded picture stored in the picture buffer 105. Specifically, the prediction processing unit 106 searches for a region having a pixel configuration having the highest similarity to the pixel configuration of the block to be encoded from the reconstructed image of another already encoded picture. do. Then, the prediction processing unit 106 refers to which of the reconstructed images of the picture (hereinafter, the information of the referenced picture is referred to as "reference picture information"), and makes the referenced picture a coding target. A predicted image is generated by deciding how much the reconstructed image deviated from the position corresponding to the block is referred to (hereinafter, the information indicating the amount of deviating position is referred to as "motion vector information").

The difference calculation unit 109 is an input image signal for each basic PU selected based on the basic CU in the basic block input from the basic block division unit 102, and a prediction image signal for each basic PU input from the prediction processing unit 106. Generates a difference image signal, which is the difference value between and. The difference calculation unit 109 outputs the generated difference image signal to the prediction residual coding unit 103.

The predictive residual coding unit 103, which is a residual coding unit, performs orthogonal transformation processing on the difference image signal input from the difference calculation unit 109, and quantizes the obtained orthogonal transformation coefficient of each frequency component. do. As a result, the predicted residual coding unit 103 generates a residual coefficient signal. The prediction residual coding unit 103 performs orthogonal transformation processing and quantization processing for each TU (Transform Unit) (hereinafter, referred to as “basic TU”), which is an orthogonal transformation unit obtained by further dividing the basic CU. Specifically, as shown in the column of "basic TU size" in FIG. 3, when the size of the basic CU is 16 x 16 pixels, one basic TU of 16 x 16 pixels or 4 of 8 x 8 pixels. It can be divided into two basic TUs. On the other hand, when the size of the basic CU is 8 × 8 pixels, it can be divided into one basic TU of 8 × 8 pixels or four basic TUs of 4 × 4 pixels. In the example shown in FIG. 3, when the basic PU is determined, the basic TU is uniquely assigned, so that the process of selecting the size of the basic TU becomes unnecessary. This makes it possible to significantly reduce the amount of processing. In addition, when a part of the basic TUs shown in the example of FIG. 3 is not used, or when a basic TU having a size not shown in the example of FIG. 3 and a size smaller than the basic PU is used. However, the same explanation is possible.

The predicted residual decoding unit 104 uses the basic TU processed by the predicted residual coding unit 103 as a processing unit. The predictive residual decoding unit 104 generates a reconstructed difference image signal by performing inverse quantization processing on the residual coefficient signal input from the predictive residual coding unit 103 and further performing inverse orthogonal transformation processing.

The addition calculation unit 110 adds the reconstructed difference image signal input from the predicted residual decoding unit 104 and the predicted image signal input from the predicted processing unit 106 in basic PU units to obtain a reconstructed image signal. Generate.

The picture buffer 105 stores the reconstructed image signal input from the addition calculation unit 110. The reconstructed image signal stored in the picture buffer 105 is referred to in the interscreen prediction process of the picture to be coded after the current coded picture.

The integration determination unit 107, which functions as an integration unit, integrates the basic CUs belonging to the plurality of basic blocks when the series of processing of the basic block unit processing loop unit 111 is completed for the plurality of basic blocks to be integrated. Then, it is determined whether or not the unit is integrated into one integrated coding unit (hereinafter referred to as "integrated CU"), and an integrated determination result signal is generated. That is, the integration determination unit 107 determines whether or not to make a plurality of basic CUs belonging to an N × N pixel (for example, 32 × 32 pixels) region composed of a plurality of basic blocks into one integrated integrated CU. .. The integration determination unit 107 integrates the mode of the first operation of outputting the basic CU to the code string generation unit 108 as it is without integrating the basic CU and a plurality of basic CUs belonging to the N × N pixel region as one new CU. It has a mode of the second operation of outputting to the code string generation unit 108. The integration determination unit 107 switches between the first operation mode and the second operation mode according to the integration determination result. That is, the integration determination unit 107 has (1) a plurality of basic CUs and basic PUs belonging to the region of N × N pixels all having the same block size, and (2) a plurality of basic PUs belonging to the region of the N × N pixels. When the prediction information of is the same, a plurality of basic CUs included in the N × N pixel region are integrated as one new CU.

The code string generation unit 108 records the residual coefficient signal input from the predicted residual coding unit 103 in the integrated CU unit or the basic CU unit according to the integrated determination result signal input from the integrated determination unit 107, and other decoding. A code string is generated by variable-length coding and arithmetic coding for the coded information signal required at the time of the conversion process. That is, the code string generation unit 108 can change the coding information set for the new CU after integration and the residual coefficient for the plurality of basic CUs before integration that belonged to the new CU after integration. Long-coded and arithmetic-coded to generate a code sequence for the new CU after integration. When the integrated CU is output from the integrated determination unit 107, the coding information set for the integrated CU and the residual coefficients for the plurality of basic CUs before integration that belonged to the integrated CU are variable-length coded. And by arithmetic coding, a code sequence for the integrated CU is generated.

As described above, in the moving image coding apparatus 100, the basic block size is limited to 16 × 16 pixels. As a result, as shown in FIG. 3, the combinations of basic CU / basic PU / basic TU that can be selected are limited to only 3 sets when in-screen prediction is selected and only 6 sets when inter-screen prediction is selected. It becomes possible to do. This makes it possible to significantly reduce the amount of processing for selecting the optimum combination in a series of processing of the basic block unit processing loop unit 111.

In the above embodiment, the basic block size is limited to 16 × 16 pixels, but the present disclosure is not limited to this. That is, the optimum combination may be selected from the combinations of FIG. 1 defined in the HEVC standard without limiting the basic block size. However, in this case, the amount of processing becomes enormous as compared with the case where the basic block size is limited. Alternatively, it is not limited to 16 × 16 pixels, but may be limited by other block sizes such as 32 × 32 pixels. For example, when the block size is limited to 32 × 32 pixels, the coding efficiency can be expected to be improved because the choices of the block sizes of CU and PU belonging to the basic block size are increased. On the other hand, the amount of processing for selecting the optimum CU and PU block size increases. Therefore, a moving image coding device that can tolerate an increase in processing amount uses a large block size as a basic block size, while a moving image coding device that cannot tolerate an increase in processing amount uses a small block size as a basic block size. You may do so.

[1-2. Operation of integrated judgment unit]
The integration determination unit 107 according to the first embodiment defines an integration area including a plurality of basic blocks. The integration determination unit 107 performs integration determination processing for all the basic blocks included in the integration area when a series of processing of the basic block unit processing loop unit 111 is completed.

A method of determining whether or not to integrate basic CUs belonging to a plurality of basic blocks into one integrated CU in the integration determination unit 107 will be specifically described with reference to FIGS. 4, 5A, and 5B. FIG. 4 is a flowchart showing the integration determination process according to the first embodiment. 5A and 5B are image diagrams showing the integration determination process according to the first embodiment. FIG. 4 shows processing when the size of the basic block is 16 × 16 pixels and the size of the integrated area is 32 × 32 pixels. At this time, the integrated area includes four basic blocks. If the size of the integrated area is larger than the size of the basic block, a size other than 32 × 32 pixels may be used depending on the size of the basic block.

First, the integration determination unit 107 determines whether or not the four basic blocks included in the integration region are all composed of a 16 × 16 pixel basic CU and a 16 × 16 pixel basic PU (S301). ..

When the condition of S301 is not satisfied (No in S301), the basic CU in the integrated region is not integrated as shown in FIG. 5A.

On the other hand, when the condition of S301 is satisfied (Yes in S301), the integration determination unit 107 determines whether or not the prediction information of the four basic PUs in the integration region are all the same (S302). Specifically, in the case of in-screen prediction, it is determined whether or not at least the in-screen prediction modes of the four basic PUs in the integrated region are all the same. That is, when all the basic PUs included in the integrated area are in-screen predictions, the integration determination unit 107 sets the first operation mode by using at least whether or not all the in-screen prediction modes are the same as the prediction information. Switch to the second operation mode. On the other hand, in the case of inter-screen prediction, it is determined whether or not at least the motion vector information and the reference picture information of the four basic PUs in the integrated region are all the same. That is, when all the basic PUs included in the integrated region are inter-screen predictions, the integration determination unit 107 uses at least whether or not the motion vector information and the reference picture information are all the same as the prediction information. 1 Switch between operation mode and second operation mode.

If the condition of S302 is not satisfied (No in S301), the basic CUs in the integrated region are not integrated as shown in FIG. 5A.

On the other hand, when the condition of S302 is satisfied (Yes in S301), the integration determination unit 107 integrates four 16 × 16 pixel basic CUs into one 32 × 32 pixel integrated CU (S303). ).

FIG. 6 is a conceptual diagram for explaining a combination of each block size that appears by performing the integration determination process. These block sizes are subject to variable-length coding and arithmetic coding in the code sequence generator 108. As compared with FIG. 3, it can be seen that the integrated CU having a CU size of 32 × 32 pixels, a PU size of 32 × 32 pixels, and a TU size of 16 × 16 pixels has been added by the integration determination process.

As described above, in the moving image coding apparatus 100 according to the first embodiment, the integrated determination unit 107 is a plurality of basic CUs and basic PUs belonging to an integrated region (a region of N × N pixels composed of a plurality of basic blocks). Are all the same block size and the prediction information of all the basic PUs included in the integrated area is the same, the plurality of basic CUs included in the integrated area are integrated as one new CU. Then, a code string is generated based on the new CU after integration.

If the integration process shown in FIG. 4 is not performed, even if the basic PUs have the same prediction information, it is necessary to individually describe the prediction information of each basic PU in the code string, so that the CU layer and the PU The code amount of the header information of the layer is wasted. On the other hand, when the integrated processing is performed, since it is only necessary to describe only one integrated prediction information in the code string, it is possible to suppress the code amount of the header information of the CU layer and the PU layer, and the processing amount can be reduced. It is possible to improve the coding efficiency without increasing it. The integration determination unit 107 integrates only the CU and the PU in the integrated CU, while the TU remains as it was before the integration. As a result, it is not necessary to reconstruct the residual coefficient signal after integration, and it is possible to convert to the integrated CU only by changing the header information of the CU layer and the PU layer.

(Embodiment 2)
Subsequently, the moving image coding apparatus 100 according to the second embodiment will be described with reference to the drawings. Since the configuration of the moving image coding device 100 is the same as that described in the first embodiment, the description thereof will be omitted.

The moving image coding device 100 according to the second embodiment is different from the moving image coding device 100 according to the first embodiment in the integrated determination process by the integrated determination unit 107.

FIG. 7 is a flowchart showing the integration determination process according to the second embodiment. 8A and 8B are image diagrams showing the integration determination process according to the second embodiment. FIG. 7 shows processing when the size of the basic block is 16 × 16 pixels and the size of the integrated area is 32 × 32 pixels. At this time, the integrated area includes four basic blocks.

First, the integration determination unit 107 determines whether or not the four basic blocks included in the integration region are all composed of a 16 × 16 pixel basic CU and a 16 × 16 pixel basic PU (S301). .. When the condition of S301 is not satisfied (No in S301), the basic CU in the integrated region is not integrated as shown in FIG. 8A. On the other hand, when the condition of S301 is satisfied (Yes in S301), the integration determination unit 107 determines whether or not the prediction information of only the basic PUs constituting the integrateable combination for the four basic PUs in the integrated region is the same. (S502 in FIG. 7). The details of the determination of S502 in FIG. 7 will be described with reference to FIG.

FIG. 9 is a conceptual diagram for explaining the conditions of the integrated determination process according to the second embodiment. As shown in FIG. 9, when the prediction information of the four basic PUs is the same, the integration determination unit 107 integrates the four basic PUs into one integrated PU of 32 × 32 pixels. Further, even if the prediction information of the four basic PUs is not all the same, if the prediction information of the two sets of basic PUs adjacent to the left and right are the same, the integration determination unit 107 integrates the upper two basic PUs. The 32 × 16 pixel PU and the lower two basic PUs are integrated into two integrated PUs of the 32 × 16 pixel PU. Further, even if the prediction information of the four basic PUs is not all the same, if the prediction information of the two sets of basic PUs adjacent to each other are the same, the integration determination unit 107 integrates the two basic PUs on the left side. It is integrated into two integrated PUs, a 16 × 32 pixel PU and a 16 × 32 pixel basic PU that integrates the two PUs on the right side. In addition, the integrated PU of 32 × 16 pixels and the integrated PU of 16 × 32 pixels can be selected for integration only in the case of inter-screen prediction, and in the case of in-screen prediction, only the integration into the integrated PU of 32 × 32 pixels can be selected. Cannot be selected.

In short, in the integration determination process according to the second embodiment, a plurality of basic PUs belonging to the integration area (N × N pixel area) are divided into one group consisting of two adjacent basic PUs. And, when the prediction information of the basic PUs belonging to each group is the same, a plurality of basic PUs included in the integrated area are integrated as one new PU. Then, in this case, the integration determination unit 107 integrates the four 16 × 16 pixel basic CUs into one 32 × 32 pixel integrated CU as shown in FIG. 8B (S303 in FIG. 7).

FIG. 10 is a conceptual diagram for explaining a combination of each block size that appears by performing the integration determination process. These block sizes are subject to variable-length coding and arithmetic coding in the code sequence generator 108. Compared with FIG. 3, the integrated CU having a CU size of 32 × 32 pixels, a PU size of 32 × 32 pixels, and a TU size of 16 × 16 pixels by the integrated determination process, and a CU size of 32 × 32 pixels. It can be seen that an integrated CU having a PU size of 32 × 16 pixels or 16 × 32 pixels and a TU size of 16 × 16 pixels has been added.

As described above, in the moving image coding apparatus 100 according to the second embodiment, the integration determination unit 107 uses a plurality of basic PUs belonging to the integration region (N × N pixel region) and two adjacent basic PUs. When divided into one group and the prediction information of the basic PUs belonging to each divided group is the same, the plurality of basic CUs included in the integrated area are integrated as one new CU. Then, a code string is generated based on the new CU after integration.

For example, in the integration determination unit 107, the prediction information of all the basic PUs included in the upper half region of the integration region (N × N pixel region) is the same information and is included in the lower half region. When the prediction information of all the basic PUs is the same information, the plurality of basic CUs included in the integrated area are integrated as one new CU. Alternatively, in the integration determination unit 107, the prediction information of all the basic PUs included in the left half region of the integration region (N × N pixel region) is the same information, and all included in the right half region. When the prediction information of the basic PU of is the same information, a plurality of basic CUs included in the integrated area are integrated as one new CU.

In the integrated process according to the first embodiment, the prediction information of the four basic PUs is integrated into the integrated CU only when they are all the same. On the other hand, in the integrated process according to the second embodiment, even if the prediction information of the two sets of basic PUs is the same, they are integrated into the integrated CU, so that more CUs can be integrated. As a result, it is possible to further suppress the code amount of the header information of the CU layer and the PU layer, and it is possible to improve the coding efficiency without increasing the processing amount.

The integration determination unit 107 integrates only the CU and the PU in the integrated CU, while the TU remains as it was before the integration. As a result, it is not necessary to reconstruct the residual coefficient signal after integration, and it is possible to convert to the integrated CU only by changing the header information of the CU layer and the PU layer.

(Embodiment 3)
Subsequently, the moving image coding apparatus 100 according to the third embodiment will be described with reference to the drawings. Since the configuration of the moving image coding device 100 is the same as that described in the first embodiment, the description thereof will be omitted.

The moving image coding device 100 according to the third embodiment is different from the moving image coding device 100 according to the first and second embodiments in the integrated determination process by the integrated determination unit 107.

The integration determination unit 107 according to the third embodiment defines a two-stage integrated area of the integrated area 1 and the integrated area 2 as an integrated area including a plurality of basic blocks. The integration determination unit 107 performs integration determination processing for all the basic blocks included in the integration area when a series of processing of the basic block unit processing loop unit 111 is completed.

A method for determining whether or not to integrate basic CUs belonging to a plurality of basic blocks into one integrated CU in the integration determination unit 107 is specifically described with reference to FIGS. 11, 12A, 12B, and 12C. explain. FIG. 11 is a flowchart showing the integration determination process according to the third embodiment. 12A, 12B, and 12C are image diagrams showing the integration determination process according to the third embodiment. FIG. 11 shows processing when the basic block is 16 × 16 pixels, the integrated area 1 is 32 × 32 pixels, and the integrated area 2 is 64 × 64 pixels. The integrated area 2 includes the integrated area 1. At this time, the integrated area 1 includes four basic blocks. The integrated area 2 includes four integrated areas 1. That is, the integrated area 2 includes 16 basic blocks. As the size of the integrated area, if the size is larger than the size of the basic block, a size other than 32 × 32 pixels and 64 × 64 pixels may be used depending on the size of the basic block.

First, the integration determination unit 107 determines whether or not the four basic blocks contained in the integration region 1 are all composed of a basic CU having 16 × 16 pixels and a basic PU having 16 × 16 pixels (S801). ).

When the condition of S801 is not satisfied (No in S801), the basic CU in the integrated region 1 is not integrated as shown in FIG. 12A.

On the other hand, when the condition of S801 is satisfied (Yes in S801), the integration determination unit 107 determines whether or not the prediction information of the four basic PUs in the integration region 1 are all the same (S802). Specifically, in the case of in-screen prediction, it is determined whether or not at least the in-screen prediction modes of the four basic PUs in the integrated region 1 are all the same. Further, in the case of inter-screen prediction, it is determined whether or not at least the motion vector information and the reference picture information of the four basic PUs in the integrated region 1 are all the same.

When the condition of S802 is not satisfied (No in S802), the basic CU in the integrated region 1 is not integrated as shown in FIG. 12A.

On the other hand, when the condition of S802 is satisfied (Yes in S802), the integration determination unit 107 integrates four 16 × 16 pixel basic CUs into one 32 × 32 pixel integrated CU 1 (S803).

The integration determination unit 107 performs a series of processes from S801 to S803 for all four integrated areas 1 belonging to the integrated area 2 (S804). That is, when the integration determination unit 107 has not completed a series of processes from S801 to S803 for all the integrated areas 1 in the integrated area 2 (No in S804), the integration determination unit 107 has S801 for the integrated area 1 for which the processes have not been completed. A series of operations from to S803 is performed. As a result, if the integration process is not performed for any of the integrated areas 1, all 16 basic CUs in the integrated area 2 are not integrated as shown in FIG. 12A. On the other hand, when only a part of the integrated areas 1 out of the four integrated areas 1 is integrated, only a part of the basic CUs in the integrated area 2 is integrated into the integrated CU1 of 32 × 32 pixels as shown in FIG. 12B. To.

Next, when the series of processes from S801 to S803 is completed for all the integrated regions 1 in the integrated region 2 (YES in S804), the integration determination unit 107 refers to the four integrated regions 1 belonging to the integrated region 2. It is determined whether or not all CUs are integrated into the integrated CU1 (S805).

If the condition of S805 is not satisfied (No in S805), the integration determination unit 107 ends the integration determination process.

When the condition of S805 is satisfied (Yes in S805), the integration determination unit 107 determines whether or not the prediction information of the four integrated PU1s in the integration region 2 are all the same (S806).

When the condition of S806 is not satisfied (No in S806), the integration determination unit 107 ends the integration determination process.

When the condition of S806 is satisfied (Yes in S806), the integration determination unit 107 further integrates the four 32 × 32 pixel integrated CU1 into one 64 × 64 pixel integrated CU2 as shown in FIG. 12C (S807). .. The moving image coding device 100 limits the size of the basic block to 16 × 16 pixels, which is smaller than the 64 × 64 pixels and 32 × 32 pixels defined by HEVC. This makes it possible to integrate 32 × 32 pixels into the integrated CU1 and 64 × 64 pixels into the integrated CU2.

FIG. 13 is a conceptual diagram for explaining a combination of each block size that appears by performing the integration determination process. These block sizes are subject to variable-length coding and arithmetic coding in the code sequence generator 108. Compared with FIG. 3, the integrated CU1 having a CU size of 32 × 32 pixels, a PU size of 32 × 32 pixels, and a TU size of 16 × 16 pixels, and a CU size of 64 × 64 pixels by the integrated determination process. It can be seen that the integrated CU2 having a configuration of a PU size of 64 × 64 pixels and a TU size of 16 × 16 pixels has been added.

As described above, in the moving image coding apparatus 100 according to the third embodiment, the integration determination unit 107 has a plurality of basic CUs and basics belonging to the integration region 1 (region of N × N pixels composed of a plurality of basic blocks). When all the PUs have the same block size and the prediction information of all the basic PUs included in the integrated region 1 is the same, the plurality of basic CUs included in the integrated region 1 are integrated as one new integrated CU1. Further, in the integration determination unit 107, all the CUs in the integration area 2 (the area consisting of the plurality of integration areas 1) are integrated into the integration CU1, and the prediction information of all the integration PU1s in the integration area 2 is obtained. If they are the same, the plurality of basic CUs included in the integrated region 2 are integrated as one new integrated CU2. Then, a code string is generated based on the new CU after integration.

In the integrated process according to the first embodiment, only four basic CUs were integrated at the maximum. On the other hand, in the integrated process according to the third embodiment, up to 16 basic CUs are integrated, and more CUs can be integrated into one CU. As a result, it is possible to further suppress the code amount of the header information of the CU layer and the PU layer, and it is possible to improve the coding efficiency without increasing the processing amount.

The integration determination unit 107 integrates only the CU and the PU in the integrated CU1 and the integrated CU2, while the TU remains as it was before the integration. As a result, it is not necessary to reconstruct the residual coefficient signal after integration, and it is possible to convert to integrated CU1 and integrated CU2 only by changing the header information of the CU layer and the PU layer.

(Other embodiments)
As described above, Embodiments 1 to 3 have been described as examples of the techniques disclosed in the present application. However, the technique in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, etc. have been made. Further, it is also possible to combine the components described in the above-described embodiments 1 to 3 to form a new embodiment.

Therefore, other embodiments will be exemplified below.

Each of the integrated determination processes described in the first to third embodiments is not limited to being used individually. That is, any one or more of the integrated determination processes described in the first to third embodiments may be used in combination. For example, in the flowchart of the third embodiment shown in FIG. 11, both or one of the steps S802 and S805 may be replaced with the step S502 in the flowchart of the second embodiment shown in FIG. 7.

Further, a program having the same function as each means included in the moving image coding apparatus 100 shown in the above-described first to third embodiments may be recorded on a recording medium such as a flexible disk. This makes it possible to easily carry out the processing shown in the above embodiment in an independent computer system. The recording medium is not limited to a flexible disk, and any optical disk, IC card, ROM cassette, or the like that can record a program can be used in the same manner.

Further, the same function as each means included in the moving image coding apparatus 100 shown in the above-described first to third embodiments may be realized as an LSI as an integrated circuit. These may be integrated into a single chip so as to include a part or all of each means. Further, the LSI may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration.

Further, the method of making an integrated circuit is not limited to the LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and settings of the circuit cells inside the LSI may be used.

Furthermore, if an integrated circuit technology that replaces an LSI or the like appears due to advances in semiconductor technology or another technology derived from it, it is naturally possible to integrate functional blocks using that technology.

Since the above-described embodiment is for exemplifying the technique in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of claims or the equivalent thereof.

The present disclosure can be applied to a moving image coding device that encodes each picture constituting an input image and outputs it as moving image coding data. For example, the present disclosure is applicable to video cameras, digital cameras, video recorders, mobile phones, personal digital assistants, personal computers, and the like.

100 Moving image coding device 101 Picture memory 102 Basic block division unit 103 Predictive residual coding unit 104 Predictive residual decoding unit 105 Picture buffer 106 Prediction processing unit 107 Integration judgment unit 108 Code string generation unit 109 Difference calculation unit 110 Addition Calculation unit 111 Basic block unit processing loop unit

Claims (4)

A moving image coding device that encodes a target picture and generates a code string.
In operation, (i) a block division unit that divides the target picture into a plurality of coding units, and (ii) divides the plurality of coding units into at least one prediction unit, respectively.
In operation, it is provided with a residual coding unit that generates a residual component by calculating a difference between a predicted image generated for each prediction unit and the target picture.
Only when the first size of the first coding unit of the plurality of coding units is 2N × 2N, the second size of the prediction unit in the first coding unit is always 2N × 2N, 2N × N and It is either N × 2N,
When the first size of the first coding unit of the plurality of coding units is not 2N × 2N, the second size of the prediction unit in the first coding unit is 2N × 2N, 2N × N, Either Nx2N or NxN,
Video coding device. When the first size of the first coding unit of the plurality of coding units is 2N × 2N, the third size of the conversion unit in the first coding unit is (i) the first coding. When the second size of the prediction unit in the unit is 2N × 2N, it is always 2N × 2N, and (ii) the second size of the prediction unit in the first coding unit is 2N × N or N. When it is × 2N, it is always N × N,
The moving image coding device according to claim 1. (I) When the first size of the first coding unit of the plurality of coding units is 2N × 2N and (ii) inter-prediction is performed, the prediction unit in the first coding unit. The second size of is always one of 2N × N and N × 2N.
The moving image coding device according to claim 1. A moving image coding device that encodes a target picture and generates a code string.
In operation, (i) a block division unit that divides the target picture into a plurality of coding units, and (ii) divides the plurality of coding units into at least one prediction unit, respectively.
In operation, it is provided with a residual coding unit that generates a residual component by calculating a difference between a predicted image generated for each prediction unit and the target picture.
Only when the first size of the first coding unit of the plurality of coding units is 4N × 4N, the second size of the prediction unit in the first coding unit is (i) when intra-prediction is performed. , Always 4N × 4N, and (ii) always one of 4N × 4N, 4N × 2N and 2N × 4N when inter-prediction is performed.
When the first size of the first coding unit of the plurality of coding units is not 2N × 2N, the second size of the prediction unit in the first coding unit is 2N × 2N, 2N × N, It is either N × 2N or N × N,
When the first size of the first coding unit of the plurality of coding units is 2N × 2N, the second size of the prediction unit in the first coding unit is (i) intra-prediction. When done, it is always either 2Nx2N and NxN, and when (ii) inter-prediction is done, it is always either 2Nx2N, 2NxN and Nx2N.
Video coding device.

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