WO2020224476A1 - 一种图像划分方法、装置及设备 - Google Patents

一种图像划分方法、装置及设备 Download PDF

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Publication number
WO2020224476A1
WO2020224476A1 PCT/CN2020/087289 CN2020087289W WO2020224476A1 WO 2020224476 A1 WO2020224476 A1 WO 2020224476A1 CN 2020087289 W CN2020087289 W CN 2020087289W WO 2020224476 A1 WO2020224476 A1 WO 2020224476A1
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current image
image block
width
maxeqtsize
height
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PCT/CN2020/087289
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English (en)
French (fr)
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杨海涛
赵寅
张恋
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华为技术有限公司
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/119—Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
    • H04N19/96—Tree coding, e.g. quad-tree coding

Definitions

  • This application relates to the field of video coding, and in particular to an image division method, device and equipment.
  • Video coding (including video coding and video encoding) is widely used in digital video applications, such as broadcast digital TV, video transmission on the Internet and mobile networks, video chat and video conferencing, etc. Security applications for conversational applications, DVD and Blu-ray discs, video content capture and editing systems, and camcorders.
  • BT binary tree
  • HBT horizontal binary tree
  • HBT vertical binary tree
  • EQT extended quad tree
  • MaxBTSize maximum BT size
  • MaxEqtSize maximum EQT size
  • the boundary LCU is divided, and image blocks with an aspect ratio of 1:8 or 8:1 may appear, such as 8 ⁇ 64 image blocks or 64 ⁇ 8 image blocks, in order to meet the constraint that the maximum aspect ratio of the coding unit is 4, image blocks with an aspect ratio of 1:8 or 8:1 must be divided. Because the division process will be affected by the maximum division depth, When the image block can only be divided once, there will be the following situations: 1) The image block continues to use EQT division, but after using EQT division, an image block or CU with an aspect ratio of 1:8 or 8:1 will be generated.
  • MaxBTSize is configured to be less than 64
  • 8 ⁇ 64 or 64 ⁇ 8 image blocks cannot use BT division. That is to say, 8x64 or 64x8 image blocks cannot use EQT division, BT division, QT division, and they cannot be divided, which will affect the coding performance.
  • the present application provides an image division method, device, and device to avoid the occurrence of image blocks that must be divided and no division method is available when dividing boundary image blocks, which affects coding performance.
  • this application provides an image division method applied to a video encoding (including encoding and decoding) process.
  • the method includes: obtaining block information of the current image block; and collecting block information from candidate division methods based on the obtained block information Determine the available division mode in the determined available division mode; determine the division mode of the current image block from the determined available division mode; according to the division mode of the current image block, obtain one or more CUs from the current image block, where the width of each CU The aspect ratio satisfies the maximum aspect ratio of the set CU.
  • the image block when the current image block is divided, the image block can be divided into one or more CUs that meet the set maximum aspect ratio of the CU, which can solve the problem of image division in the prior art. Due to the limitation of the maximum aspect ratio of the CU, the problem of image blocks that must be divided but cannot be divided occurs, which can improve the coding performance.
  • the block information of the current image block may include size information of the current image block, such as the width of the current image block, the height of the current image block, or the area obtained based on the width and height of the current image block.
  • the block information of the current image block may also include the coordinates of the pixels in the current image block, for example, the coordinates of the pixels in the current image block in the image coordinate system, where the origin of the image coordinate system is the upper left corner of the image where the current image block is located.
  • the horizontal axis of the image coordinate system is the width direction (x axis) of the image where the current image block is located
  • the vertical axis of the image coordinate system is the height direction (y axis) of the image where the current image block is located.
  • the block information of the current image may also include other image-related information corresponding to the current image block, for example, whether the current image block exceeds the boundary of the current image, for the video decoder device, the block information can be parsed from the code stream of the current image Or derived.
  • the following methods can be used to determine whether the current image block exceeds the boundary of the image where the current image block is located: obtain the coordinates (x, y) of a pixel in the current image block according to the block information of the image block; determine the coordinates of the pixel point Whether (x, y) meets the preset condition, if the coordinate (x, y) of the pixel meets the first preset condition, it means that the current image block is out of the right boundary of the image where the current image block is located. If the coordinate of the pixel (x , Y) If the second preset condition is met, it indicates that the image block exceeds the lower boundary of the image where the current image block is located.
  • the coordinates (x, y) of the pixel meet the third preset condition, it indicates that the current image block exceeds the current image block The right boundary of the image where it is and exceeds the lower boundary of the current image (referred to as the lower right boundary). If the coordinates (x, y) of the pixel meet the fourth preset condition, it indicates that the current image block exceeds the boundary of the image where the current image block is located. That is, the picture may exceed the lower border of the image, or the right border of the image, or the lower right border of the image.
  • the selected pixels are used to represent the current image block, and specific pixels in the current image block can be selected to represent the current image block, such as selecting the pixel points of the vertices of the current image block, such as the pixel points of the upper left vertex and the upper right vertex
  • select the pixel at the center of the current image block and you can also select any pixel in the current image block except the above-mentioned pixels.
  • the aforementioned first preset condition, second preset condition, third preset condition, and fourth preset condition can be determined according to the position of the selected pixel and the size of the image where the current image block is located.
  • the maximum aspect ratio of the set CU may be 4 or 8.
  • the set of candidate division methods includes, but is not limited to, non-division, horizontal binary tree HBT division, vertical binary tree VBT division, horizontally expanded quadtree HEQT division, vertically expanded quadtree VEQT division, and four One or more of the fork tree QT division methods.
  • determining the available division mode from the set of candidate division modes specifically includes the following steps: according to the block information, judging whether the current image block meets the first condition, and when the current image block meets the first condition At the time, determine the VBT division method as the available division method.
  • the first condition is width>height*MaxPartRatio
  • width is the width of the current image block
  • height is the height of the current image block
  • MaxPartRatio is the maximum aspect ratio of the set CU.
  • this application relaxes the conditions for using the VBT division method.
  • the VBT division method can be adopted . In order to avoid the appearance of image blocks whose aspect ratio does not meet the set maximum CU aspect ratio (image blocks that must be divided but cannot be divided), and the coding performance is improved.
  • determining the available partitioning method from the candidate partitioning method set specifically includes the following steps: According to the block information, determining the available partitioning method from the candidate partitioning method set specifically includes the following steps: The block information determines whether the current image block meets the second condition; when the current image block meets the second condition, it is determined that the HBT division mode is an available division mode. Among them, the second condition is height>width*MaxPartRatio, width is the width of the current image block, height is the height of the current image block, and MaxPartRatio is the maximum aspect ratio of the set CU.
  • this application relaxes the conditions for using the HBT division method.
  • the HBT division method can be adopted . In order to avoid the appearance of image blocks whose aspect ratio does not meet the set maximum CU aspect ratio (image blocks that must be divided but cannot be divided), and the coding performance is improved.
  • determining the available division mode from the candidate division mode set specifically includes the following steps: according to the block information, judging whether the current image block satisfies the conditions in the first condition set; when the current image block When all the conditions in the first condition set are met, it is determined that the VEQT division mode is an available division mode.
  • the first condition set includes the following conditions: (1) width ⁇ MaxEqtSize; (2) height ⁇ MaxEqtSize; (3) height ⁇ MinEqtSize*2; (4) width ⁇ MinEqtSize*4; (5) height*4 ⁇ MaxPartRatio *width; (6) height*MaxPartRatio ⁇ width; where width is the width of the current image block, height is the height of the current image block, MaxEqtSize is the size of the maximum EQT set, and MinEqtSize is the size of the minimum EQT set. MaxPartRatio is the maximum aspect ratio of the set CU.
  • this application tightens the conditions for using the VEQT division method to try to avoid image blocks with an aspect ratio that does not meet the set maximum CU aspect ratio (images that must be divided but cannot be divided) Block) to improve coding performance.
  • determining the available division mode from the candidate division mode set specifically includes the following steps: according to the block information, judging whether the current image block satisfies the conditions in the second condition set; when the current image block When all the conditions in the second condition set are met, it is determined that the HEQT division mode is an available division mode.
  • the second condition set includes the following conditions: (1) width ⁇ MaxEqtSize; (2) height ⁇ MaxEqtSize; (3)width ⁇ MinEqtSize*2; (4)height ⁇ MinEqtSize*4; (5)width*4 ⁇ MaxPartRatio *height; (7) width*MaxPartRatio ⁇ height; where width is the width of the current image block, heigh is the height of the current image block, MaxEqtSize is the maximum EQT size, MinEqtSize is the minimum EQT size, and MaxPartRatio is the maximum width of the CU High ratio.
  • this application tightens the conditions for using the HEQT division method to try to avoid the appearance of image blocks whose aspect ratio does not meet the set maximum CU aspect ratio (images that must be divided but cannot be divided) Block) to improve coding performance.
  • the method further includes determining that the current image block is within the boundary of the image where the current image block is located according to the block information of the current image block.
  • the third condition is: (x0+width) ⁇ PicWidth, and (y0+height) ⁇ PicHeight
  • x0 is the abscissa of the pixel of the upper left vertex of the current image block in the image coordinate system
  • y0 is the current image in the image coordinate system
  • the ordinate of the pixel of the upper left vertex of the block, the origin of the image coordinate system is the pixel of the upper left vertex of the image where the current image block is located
  • the horizontal axis of the image coordinate system is the width direction of the image where the current image block is located
  • the image coordinate system The vertical axis of is the height direction of the image where the current image block is located
  • PicWidth is the width of the image where the current image block is located
  • PicHeight is the height of the image where the current image block is located.
  • the method further includes determining, according to the block information of the current image block, that the current image block exceeds the boundary of the image where the current image block is located, and according to the block information of the current image block, the set maximum BT size, and the setting Determine whether the QT division method is an available division method by setting the size of the maximum EQT.
  • the current image block exceeds the boundary of the image where the current image block is located by the following method: judging whether the current image block meets the fourth condition according to the block information of the current image block; when the current image block meets the first For the four conditions, it is determined that the current image block exceeds the boundary of the current image block.
  • the fourth condition is: (x0+width)>PicWidth, and (y0+height)>PicHeight
  • x0 is the abscissa of the pixel point of the upper left vertex of the current image block in the image coordinate system
  • y0 is the current image in the image coordinate system
  • the ordinate of the pixel of the upper left vertex of the block, the origin of the image coordinate system is the pixel of the upper left vertex of the image where the current image block is located
  • the horizontal axis of the image coordinate system is the width direction of the image where the current image block is located
  • the image coordinate system The vertical axis of is the height direction of the image where the current image block is located
  • PicWidth is the width of the image where the current image block is located
  • PicHeight is the height of the image where the current image block is located.
  • the QT division method is an available division method in the following way: according to the block information of the image block, determine whether the current image block satisfies the third The conditions in the condition set; if the current image block satisfies at least one condition in the third condition set, the QT division mode is an available division mode.
  • the third condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; width is the width of the current image block, heigh is the height of the current image block, MaxBTSize is the size of the set maximum BT, MaxEqtSize is the size of the maximum EQT set, and max(
  • the QT division method when the current image block exceeds the boundary of the image where the current image block is located, it can be judged whether the QT division method is an available division method in the following way: according to the block information of the image block, it is judged whether the current image block satisfies the fourth The conditions in the condition set; if the current image block satisfies at least one condition in the fourth condition set, the QT division mode is an available division mode.
  • the fourth condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width >MaxEqtSize, height>MaxBTSize, and height>MaxEqtSize; (4) width>max(MaxBTSize, MaxEqtSize); (5) height>max(MaxBTSize, MaxEqtSize); (6) width>max(MaxBTSize, MaxEqtSize), and height >max(MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; (11) the current image block does not exceed the right of the image where the image block is located Boundary, and does not exceed the lower boundary of the image where the image block is located; width is the width of the current image block, heigh is the height of
  • the QT division method is adopted to avoid dividing the boundary image block to obtain an N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image block. Furthermore, when MaxBTSize and MaxEqtSize are set to be less than 64, the problem that N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image blocks cannot continue to be divided is avoided.
  • MaxEqtSize is 2 M , where the value of M is 3, 4, 5, or 6.
  • the current image block division method can be determined from the determined available division methods in the following manner: when there is one available division method, the available division method is determined as the current image Block division method; when there are multiple available division methods, analyze the code stream including the current image block according to the determined available division method, and determine the current image block division method according to the analysis result.
  • the division method of the current image block can be determined from the determined available division methods in the following manner: when the available division method is one, the available division method is determined as the current image Block division method; when there are multiple available division methods, the rate-distortion cost of each available division method is determined separately, and the available division method with the smallest rate-distortion cost among the available division methods is determined as the current image block division method.
  • this application also provides another image division method, which is applied to the video encoding process.
  • the method includes: obtaining block information of the current image block; and determining the available division from the set of candidate division methods according to the obtained block information Method, where, when the current image block exceeds the boundary of the image where the current image block is located, the QT division in the set of candidate division methods is determined according to the block information of the current image block, the size of the maximum BT set, and the size of the maximum EQT.
  • the method is an available partition method; from the determined available partition methods, determine the current image block partition method; according to the current image block partition method, obtain one or more CUs from the current image block.
  • the block information of the current image block may include size information of the current image block, such as the width of the current image block, the height of the current image block, or the area obtained based on the width and height of the current image block.
  • the block information of the current image block may also include the coordinates of the pixels in the current image block, for example, the coordinates of the pixels in the current image block in the image coordinate system, where the origin of the image coordinate system is the upper left corner of the image where the current image block is located.
  • the horizontal axis of the image coordinate system is the width direction (x axis) of the image where the current image block is located
  • the vertical axis of the image coordinate system is the height direction (y axis) of the image where the current image block is located.
  • the block information of the current image may also include other image-related information corresponding to the current image block, for example, whether the current image block exceeds the boundary of the current image, for the video decoder device, the block information can be parsed from the code stream of the current image Or derived.
  • the set of candidate partitioning methods may also include, but are not limited to, no partitioning method, horizontal binary tree HBT partitioning method, vertical binary tree VBT partitioning method, horizontally extended quadtree HEQT partitioning method, and vertically extended quadtree VEQT partitioning One or more of the ways.
  • the current image block exceeds the boundary of the image where the current image block is located by the following method: judging whether the current image block meets the fourth condition according to the block information of the current image block; when the current image block meets the first For the four conditions, it is determined that the current image block exceeds the boundary of the current image block.
  • the fourth condition is: (x0+width)>PicWidth, and (y0+height)>PicHeight
  • x0 is the abscissa of the pixel point of the upper left vertex of the current image block in the image coordinate system
  • y0 is the current image in the image coordinate system
  • the ordinate of the pixel of the upper left vertex of the block, the origin of the image coordinate system is the pixel of the upper left vertex of the image where the current image block is located
  • the horizontal axis of the image coordinate system is the width direction of the image where the current image block is located
  • the image coordinate system The vertical axis of is the height direction of the image where the current image block is located
  • PicWidth is the width of the image where the current image block is located
  • PicHeight is the height of the image where the current image block is located.
  • the QT division method when the current image block exceeds the boundary of the image where the current image block is located, it can be judged whether the QT division method is an available division method in the following way: according to the block information of the image block, it is judged whether the current image block satisfies the first The conditions in the condition set; if the current image block satisfies at least one condition in the first condition set, the QT division mode is an available division mode.
  • the first condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; width is the width of the current image block, heigh is the height of the current image block, MaxBTSize is the size of the set maximum BT, MaxEqtSize is the size of the maximum EQT set, and max(MaxBTS
  • the QT division method is an available division method by the following method: According to the block information of the image block, it is determined whether the current image block satisfies the second The conditions in the condition set; if the current image block satisfies at least one condition in the second condition set, the QT division mode is an available division mode.
  • the second condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; (11) the current image block does not exceed the right boundary of the image where the image block is located, And does not exceed the lower boundary of the image where the image block is located; width is the width of the current image block, heigh is the height of
  • the QT division method is adopted to avoid dividing the boundary image block to obtain an N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image block. Furthermore, when MaxBTSize and MaxEqtSize are set to be less than 64, the problem that N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image blocks cannot continue to be divided is avoided.
  • MaxEqtSize is 2 M , where the value of M is 3, 4, 5, or 6.
  • the current image block division method can be determined from the determined available division methods in the following manner: when there is one available division method, the available division method is determined as the current image Block division method; when there are multiple available division methods, analyze the code stream including the current image block according to the determined available division method, and determine the current image block division method according to the analysis result.
  • the division method of the current image block can be determined from the determined available division methods in the following manner: when the available division method is one, the available division method is determined as the current image Block division method; when there are multiple available division methods, the rate-distortion cost of each available division method is determined separately, and the available division method with the smallest rate-distortion cost among the available division methods is determined as the current image block division method.
  • the present application also provides an image division device, which has a function of implementing the image division method described in any one of the possible implementations described in the first aspect.
  • the image division device includes an acquisition unit, a determination unit, and a division unit. These units can perform the corresponding functions in the method example described in the first aspect. For details, please refer to the detailed description in the method example, which will not be repeated here.
  • this application also provides a video encoding device that has a function of implementing the image division method described in any one of the possible implementations of the first aspect.
  • the structure of the video encoding device includes a memory and a processor, and the processor is configured to support the video encoding device to perform a corresponding function in the method described in any one of the possible implementations of the first aspect.
  • the memory is coupled with the processor, and it stores the necessary program instructions and data of the video encoding device.
  • this application also provides another image division device, which has the function of realizing the image division method described in any one of the possible implementation manners described in the second aspect.
  • the image division device includes an acquisition unit, a determination unit, and a division unit. These units can perform corresponding functions in the method example described in the second aspect. For details, refer to the detailed description in the method example, which is not repeated here.
  • this application also provides another video encoding device, which has the function of implementing the image division method described in any one of the possible implementations of the second aspect.
  • the structure of the video encoding device includes a memory and a processor, and the processor is configured to support the video encoding device to perform a corresponding function in the method described in any one of the possible implementation manners of the second aspect.
  • the memory is coupled with the processor, and it stores the necessary program instructions and data of the video encoding device.
  • the present application also provides a computer storage medium in which a software program is stored, and the software program can implement any one of the implementation modes of any aspect when read and executed by one or more processors Provided method.
  • this application also provides a computer program product containing instructions, which when run on a computer, causes the computer to execute any method in any of the above aspects.
  • FIG. 1A is a schematic structural diagram of a video encoding and decoding system provided by an embodiment of the application
  • FIG. 1B is a schematic structural diagram of a video decoding system provided by an embodiment of this application.
  • FIG. 2 is a schematic structural diagram of an encoder provided by an embodiment of the application.
  • Figure 3 is a schematic structural diagram of a decoder provided by an embodiment of the application.
  • FIG. 4 is a schematic structural diagram of a video decoding device provided by an embodiment of this application.
  • FIG. 5 is a schematic structural diagram of another video decoding device provided by an embodiment of this application.
  • FIG. 6 is a schematic diagram of a division method of a binary tree, a quad tree, and an extended quad tree provided by an embodiment of the application;
  • FIG. 7 is a schematic diagram of QT-MTT division provided by an embodiment of the application.
  • FIG. 8 is a schematic flowchart of an image division method provided by an embodiment of this application.
  • FIG. 9 is a schematic diagram of an image coordinate system provided by an embodiment of the application.
  • FIG. 10 is a schematic flowchart of another image division method provided by an embodiment of the application.
  • FIG. 11 is a schematic structural diagram of an image dividing device provided by an embodiment of the application.
  • FIG. 12 is a schematic structural diagram of a video encoding device provided by an embodiment of the application.
  • each frame of image needs to be divided into LCUs of equal size first, and the LCUs are recursively divided into one or more CUs.
  • the size of the LCU is 128x128 or 64x64, using the QT cascade BT/EQT division method, that is, the first level coding tree (coding tree).
  • the nodes on the) can only be divided into sub-nodes using QT.
  • the leaf nodes of the first-level coding tree are the root nodes of the second-level coding tree; the nodes on the second-level coding tree can be divided by either BT or EQT. Are child nodes; the leaf nodes of the second level coding tree are coding units. It should be noted that when the leaf node is divided into BT or EQT, its leaf node can only use the BT or EQT division, but not the QT.
  • the partial syntax of the existing AVS3 coding tree definition is shown in Table 1.
  • Table 1 For the maximum aspect ratio (MaxPartRatio) of some coding units (CU), the boundary When the LCU is divided, there may be image blocks that must be divided and no division method is available.
  • MaxPartRatio maximum aspect ratio
  • the boundary LCU is divided, and image blocks with an aspect ratio of 1:8 or 8:1 may appear, such as 8x64 image blocks or 64x8 images
  • the image block with the aspect ratio of 1:8 or 8:1 must be divided, because the division process will be affected by the maximum division depth, when the image block When it can only be divided once, there will be the following situations: 1) The image block will continue to be divided by EQT, but after the EQT division is used, an image block or CU with an aspect ratio of 1:8 or 8:1 will be generated, at this time EQT division The method is not available; 2) When MaxBTSize is configured to be less than 64, 8x64 or 64x8 image blocks cannot be divided by BT. That is to say, 8x64 or 64x8 image blocks cannot use EQT division, BT division, QT division, and they cannot be divided, which
  • the present application provides an image division method, device and device.
  • the methods and devices described in the embodiments of the present application are based on the same concept. Since the principles of the methods and devices for solving problems are similar, the implementation of the devices and the methods can be referred to each other, and the repetition will not be repeated.
  • the corresponding device may include one or more units such as functional units to perform the described one or more method steps (for example, one unit performs one or more steps). , Or multiple units, each of which performs one or more of multiple steps), even if such one or more units are not explicitly described or illustrated in the drawings.
  • the corresponding method may include one step to perform the functionality of one or more units (for example, one step performs one or more units). The functionality, or multiple steps, each of which performs the functionality of one or more of the multiple units), even if such one or more steps are not explicitly described or illustrated in the drawings.
  • Video coding generally refers to processing a sequence of pictures that form a video or video sequence.
  • the terms "picture”, "frame” or “image” can be used as synonyms.
  • Video encoding used in this article means video encoding or video decoding.
  • Video encoding is performed on the source side and usually includes processing (for example, by compressing) the original video picture to reduce the amount of data required to represent the video picture, so as to store and/or transmit more efficiently.
  • Video decoding is performed on the destination side and usually involves inverse processing relative to the encoder to reconstruct the video picture.
  • the “encoding” of video pictures involved in the embodiments should be understood as involving “encoding” or “decoding” of a video sequence.
  • the combination of the encoding part and the decoding part is also called codec (encoding and decoding).
  • a video sequence includes a series of pictures, the pictures are further divided into slices, and the slices are divided into blocks.
  • Video coding is performed in units of blocks.
  • the concept of blocks is further expanded.
  • MB macroblock
  • the macroblock can be further divided into multiple prediction blocks (partitions) that can be used for predictive coding.
  • PU prediction unit
  • TU transform unit
  • the video coding standard divides a frame of image into non-overlapping coding tree units (coding tree units, CTU), and then divides a CTU into several sub-nodes, and these sub-nodes can be performed in accordance with a quad tree (quad tree, QT). Divided into smaller sub-nodes, and smaller sub-nodes can continue to be divided to form a quadtree structure. If the node is no longer divided, it is called CU.
  • the CU is the basic unit for dividing and encoding encoded images.
  • PU can correspond to prediction block and is the basic unit of prediction coding.
  • the CU is further divided into multiple PUs according to the division mode.
  • the TU can correspond to the transform block and is the basic unit for transforming the prediction residual.
  • no matter CU, PU or TU they all belong to the concept of block (or image block) in nature.
  • a CTU is split into multiple CUs by using a quadtree structure represented as a coding tree.
  • a decision is made at the CU level whether to use inter-picture (temporal) or intra-picture (spatial) prediction to encode picture regions.
  • Each CU can be further split into one, two or four PUs according to the PU split type.
  • the same prediction process is applied in a PU, and relevant information is transmitted to the decoder on the basis of the PU.
  • the CU may be divided into TUs according to other quadtree structures similar to the coding tree used for the CU.
  • quad-tree and binary tree quad-tree and binary tree (quad-tree and binary tree, QTBT) are used to divide frames to divide coding blocks.
  • the CU may have a square or rectangular shape.
  • the image block to be encoded in the currently encoded image may be referred to as the current block.
  • the current block in encoding, it refers to the block currently being encoded; in decoding, it refers to the block currently being decoded.
  • the decoded image block used to predict the current block in the reference image is called a reference block, that is, a reference block is a block that provides a reference signal for the current block, where the reference signal represents the pixel value in the image block.
  • the block in the reference image that provides the prediction signal for the current block may be a prediction block, where the prediction signal represents the pixel value or sample value or sample signal in the prediction block. For example, after traversing multiple reference blocks, the best reference block is found. This best reference block will provide prediction for the current block, and this block is called a prediction block.
  • the original video picture can be reconstructed, that is, the reconstructed video picture has the same quality as the original video picture (assuming no transmission loss or other data loss during storage or transmission).
  • quantization is performed to perform further compression to reduce the amount of data required to represent the video picture, and the decoder side cannot completely reconstruct the video picture, that is, the quality of the reconstructed video picture is compared with the original video picture The quality is low or poor.
  • Video coding standards of H.261 belong to "lossy hybrid video coding and decoding” (that is, combining spatial and temporal prediction in the sample domain with 2D transform coding for applying quantization in the transform domain).
  • Each picture of a video sequence is usually divided into a set of non-overlapping blocks, and is usually coded at the block level.
  • the encoder side usually processes the video at the block (video block) level, that is, encodes the video.
  • the prediction block is generated by spatial (intra-picture) prediction and temporal (inter-picture) prediction, from the current block (currently processed or to be processed).
  • the processed block subtracts the prediction block to obtain the residual block, transforms the residual block in the transform domain and quantizes the residual block to reduce the amount of data to be transmitted (compressed), and the decoder side will process the inverse of the encoder Partially applied to the coded or compressed block to reconstruct the current block for representation.
  • the encoder duplicates the decoder processing loop, so that the encoder and the decoder generate the same prediction (for example, intra prediction and inter prediction) and/or reconstruction for processing, that is, to encode subsequent blocks.
  • FIG. 1A exemplarily shows a schematic structural block diagram of a video encoding and decoding system 10 applied in an embodiment of the present application.
  • the video encoding and decoding system 10 may include a source device 12 and a destination device 14, wherein, The source device 12 generates encoded video data. Therefore, the source device 12 can be referred to as a video encoding device; the destination device 14 can decode the encoded video data generated by the source device 12. Therefore, the destination device 14 It can be called a video decoding device.
  • Various implementations of source device 12, destination device 14, or both may include one or more processors and memory coupled to the one or more processors.
  • the memory may include but is not limited to random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), fast Flash memory or any other medium that can be used to store the desired program code in the form of instructions or data structures accessible by a computer, as described herein.
  • the source device 12 and the destination device 14 may include various devices, including desktop computers, mobile computing devices, notebook (for example, laptop) computers, tablet computers, set-top boxes, telephone handsets such as so-called "smart" phones. Computers, televisions, cameras, display devices, digital media players, video game consoles, on-board computers, wireless communication equipment, or the like.
  • FIG. 1A shows the source device 12 and the destination device 14 as separate devices
  • the device embodiment may also include the source device 12 and the destination device 14 or the functionality of both, that is, the source device 12 or the corresponding The functionality of the destination device 14 or the corresponding functionality.
  • the same hardware and/or software may be used, or separate hardware and/or software, or any combination thereof may be used to implement the source device 12 or the corresponding functionality and the destination device 14 or the corresponding functionality .
  • the source device 12 and the destination device 14 may communicate with each other via a link 13, and the destination device 14 may receive encoded video data from the source device 12 via the link 13.
  • Link 13 may include one or more media or devices capable of moving encoded video data from source device 12 to destination device 14.
  • link 13 may include one or more communication media that enable source device 12 to transmit encoded video data directly to destination device 14 in real time.
  • the source device 12 may modulate the encoded video data according to a communication standard, such as a wireless communication protocol, and may transmit the modulated video data to the destination device 14.
  • the one or more communication media may include wireless and/or wired communication media, such as a radio frequency (RF) spectrum or one or more physical transmission lines.
  • RF radio frequency
  • the one or more communication media may form part of a packet-based network, such as a local area network, a wide area network, or a global network (e.g., the Internet).
  • the one or more communication media may include routers, switches, base stations, or other devices that facilitate communication from source device 12 to destination device 14.
  • the source device 12 includes an encoder 20, and optionally, the source device 12 may also include a picture source 16, a picture preprocessor 18, and a communication interface 22.
  • the encoder 20, the picture source 16, the picture preprocessor 18, and the communication interface 22 may be hardware components in the source device 12, or may be software programs in the source device 12. They are described as follows:
  • the picture source 16 which can include or can be any type of picture capture device, for example to capture real-world pictures, and/or any type of pictures or comments (for screen content encoding, some text on the screen is also considered to be encoded Picture or part of an image) generating equipment, for example, a computer graphics processor for generating computer animation pictures, or for obtaining and/or providing real world pictures, computer animation pictures (for example, screen content, virtual reality, VR) pictures), and/or any combination thereof (for example, augmented reality (AR) pictures).
  • the picture source 16 may be a camera for capturing pictures or a memory for storing pictures.
  • the picture source 16 may also include any type of (internal or external) interface for storing previously captured or generated pictures and/or acquiring or receiving pictures.
  • the picture source 16 When the picture source 16 is a camera, the picture source 16 may be, for example, a local or an integrated camera integrated in the source device; when the picture source 16 is a memory, the picture source 16 may be local or, for example, an integrated camera integrated in the source device. Memory.
  • the interface When the picture source 16 includes an interface, the interface may be, for example, an external interface for receiving pictures from an external video source.
  • the external video source is, for example, an external picture capturing device, such as a camera, an external memory, or an external picture generating device, such as It is an external computer graphics processor, computer or server.
  • the interface can be any type of interface according to any proprietary or standardized interface protocol, such as a wired or wireless interface, and an optical interface.
  • a picture can be regarded as a two-dimensional array or matrix of picture elements.
  • the pixel points in the array can also be called sampling points.
  • the number of sampling points of the array or picture in the horizontal and vertical directions (or axis) defines the size and/or resolution of the picture.
  • three color components are usually used, that is, pictures can be represented as or contain three sample arrays.
  • a picture includes corresponding red, green, and blue sample arrays.
  • each pixel is usually expressed in a luminance/chrominance format or color space.
  • a picture in the YUV format includes the luminance component indicated by Y (sometimes indicated by L) and the two indicated by U and V. Chrominance components.
  • the luma component Y represents brightness or gray level intensity (for example, the two are the same in a grayscale picture), and the two chroma components U and V represent chroma or color information components.
  • a picture in the YUV format includes a luminance sample array of luminance sample values (Y), and two chrominance sample arrays of chrominance values (U and V).
  • Pictures in RGB format can be converted or converted to YUV format, and vice versa. This process is also called color conversion or conversion. If the picture is black and white, the picture may only include the luminance sample array.
  • the picture transmitted from the picture source 16 to the picture processor may also be referred to as original picture data 17.
  • the picture preprocessor 18 is configured to receive the original picture data 17 and perform preprocessing on the original picture data 17 to obtain the preprocessed picture 19 or the preprocessed picture data 19.
  • the pre-processing performed by the picture pre-processor 18 may include trimming, color format conversion (for example, conversion from RGB format to YUV format), toning, or denoising.
  • the encoder 20 (or video encoder 20) is configured to receive the pre-processed picture data 19, and process the pre-processed picture data 19 using a relevant prediction mode (such as the prediction mode in the various embodiments herein), thereby
  • the encoded picture data 21 is provided (the structure details of the encoder 20 will be described further based on FIG. 2 or FIG. 4 or FIG. 5).
  • the communication interface 22 can be used to receive the encoded picture data 21, and can transmit the encoded picture data 21 to the destination device 14 or any other device (such as a memory) via the link 13 for storage or direct reconstruction, so The other device can be any device used for decoding or storage.
  • the communication interface 22 may be used, for example, to encapsulate the encoded picture data 21 into a suitable format, such as a data packet, for transmission on the link 13.
  • the destination device 14 includes a decoder 30, and optionally, the destination device 14 may also include a communication interface 28, a picture post processor 32, and a display device 34. They are described as follows:
  • the communication interface 28 may be used to receive the encoded picture data 21 from the source device 12 or any other source, for example, a storage device, and the storage device is, for example, an encoded picture data storage device.
  • the communication interface 28 can be used to transmit or receive the encoded picture data 21 via the link 13 between the source device 12 and the destination device 14 or via any type of network.
  • the link 13 is, for example, a direct wired or wireless connection.
  • the type of network is, for example, a wired or wireless network or any combination thereof, or any type of private network and public network, or any combination thereof.
  • the communication interface 28 may be used, for example, to decapsulate the data packet transmitted by the communication interface 22 to obtain the encoded picture data 21.
  • Both the communication interface 28 and the communication interface 22 can be configured as a one-way communication interface or a two-way communication interface, and can be used, for example, to send and receive messages to establish connections, confirm and exchange any other communication links and/or, for example, encoded picture data Information about the transmission of the transmitted data.
  • the decoder 30 (or referred to as the decoder 30) is used to receive the encoded picture data 21 and provide the decoded picture data 31 or the decoded picture 31 (below will further describe the decoder 30 based on Figure 3 or Figure 4 or Figure 5 Structural details).
  • the decoder 30 may be used to execute the various embodiments described below to realize the application of the video decoding method described in this application on the decoding side.
  • the picture post processor 32 is configured to perform post-processing on the decoded picture data 31 (also referred to as reconstructed picture data) to obtain post-processed picture data 33.
  • the post-processing performed by the picture post-processor 32 may include: color format conversion (for example, conversion from YUV format to RGB format), toning, trimming or resampling, or any other processing, and can also be used to convert post-processed picture data 33 Transmission to display device 34.
  • the display device 34 is configured to receive the post-processed image data 33 to display the image to, for example, users or viewers.
  • the display device 34 may be or may include any type of display for presenting reconstructed pictures, for example, an integrated or external display or monitor.
  • the display may include a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a plasma display, a projector, a micro LED display, a liquid crystal on silicon (LCoS), Digital light processor (digital light processor, DLP) or any other type of display.
  • FIG. 1A shows the source device 12 and the destination device 14 as separate devices
  • the device embodiment may also include the source device 12 and the destination device 14 or the functionality of both, that is, the source device 12 or Corresponding functionality and destination device 14 or corresponding functionality.
  • the same hardware and/or software may be used, or separate hardware and/or software, or any combination thereof may be used to implement the source device 12 or the corresponding functionality and the destination device 14 or the corresponding functionality .
  • the source device 12 and the destination device 14 may include any of a variety of devices, including any type of handheld or stationary device, for example, a notebook or laptop computer, mobile phone, smart phone, tablet or tablet computer, video camera, desktop Computers, set-top boxes, televisions, cameras, in-vehicle devices, display devices, digital media players, video game consoles, video streaming devices (such as content service servers or content distribution servers), broadcast receiver devices, broadcast transmitter devices And so on, and can not use or use any type of operating system.
  • a notebook or laptop computer mobile phone, smart phone, tablet or tablet computer
  • video camera desktop Computers
  • set-top boxes televisions, cameras, in-vehicle devices, display devices, digital media players, video game consoles, video streaming devices (such as content service servers or content distribution servers), broadcast receiver devices, broadcast transmitter devices And so on, and can not use or use any type of operating system.
  • Both the encoder 20 and the decoder 30 can be implemented as any of various suitable circuits, for example, one or more microprocessors, digital signal processors (digital signal processors, DSP), and application-specific integrated circuits (application-specific integrated circuits). circuit, ASIC), field-programmable gate array (FPGA), discrete logic, hardware, or any combination thereof.
  • the device can store the instructions of the software in a suitable non-transitory computer-readable storage medium, and can use one or more processors to execute the instructions in hardware to execute the technology of the present disclosure . Any of the foregoing content (including hardware, software, a combination of hardware and software, etc.) can be regarded as one or more processors.
  • the video encoding and decoding system 10 shown in FIG. 1A is only an example, and the technology of this application can be applied to video encoding settings that do not necessarily include any data communication between encoding and decoding devices (for example, video encoding or video encoding). decoding).
  • the data can be retrieved from local storage, streamed on the network, etc.
  • the video encoding device can encode data and store the data to the memory, and/or the video decoding device can retrieve the data from the memory and decode the data.
  • encoding and decoding are performed by devices that do not communicate with each other but only encode data to the memory and/or retrieve data from the memory and decode the data.
  • FIG. 1B is an explanatory diagram of an example of a video decoding system 40 including the encoder 20 of FIG. 2 and/or the decoder 30 of FIG. 3 according to an exemplary embodiment, and the video decoding system 40 can implement this Apply for a combination of various technologies in the embodiments.
  • the video coding system 40 may include an imaging device 41, an encoder 20, a decoder 30 (and/or a video encoder/decoder implemented by a logic circuit 47), an antenna 42, one or more A processor 43, one or more memories 44 and/or a display device 45.
  • the imaging device 41, the antenna 42, the logic circuit 47, the encoder 20, the decoder 30, the processor 43, the memory 44, and/or the display device 45 can communicate with each other.
  • the encoder 20 and the decoder 30 are used to illustrate the video coding system 40, in different examples, the video coding system 40 may include only the encoder 20 or only the decoder 30.
  • antenna 42 may be used to transmit or receive an encoded bitstream of video data.
  • the display device 45 may be used to present video data.
  • the logic circuit 47 may include application-specific integrated circuit (ASIC) logic, graphics processor, general purpose processor, and so on.
  • the video decoding system 40 may also include an optional processor 43, and the optional processor 43 may similarly include ASIC logic, a graphics processor, a general-purpose processor, and the like.
  • the logic circuit 47 may be implemented by hardware, such as dedicated hardware for video encoding, and the processor 43 may be implemented by general software, an operating system, and the like.
  • the memory 44 may be any type of memory, such as volatile memory (for example, static random access memory (SRAM), dynamic random access memory (DRAM), etc.) or non-volatile memory. Memory (for example, flash memory, etc.), etc.
  • the memory 44 may be implemented by cache memory.
  • the logic circuit 47 may access the memory 44 (e.g., to implement an image buffer). In other examples, the logic circuit 47 may include memory (e.g., cache, etc.) for implementing image buffers and the like.
  • the encoder 20 implemented by logic circuits may include an image buffer (implemented by the memory 44) and a graphics processing unit.
  • the graphics processing unit may be communicatively coupled to the image buffer.
  • the graphics processing unit may include an encoder 20 implemented by a logic circuit 47 to implement various modules discussed with reference to FIG. 2 and/or any other encoder system or subsystem described herein.
  • Logic circuits can be used to perform the various operations discussed herein.
  • decoder 30 may be implemented by logic circuit 47 in a similar manner to implement the various modules discussed with reference to decoder 30 of FIG. 3 and/or any other decoder systems or subsystems described herein.
  • the decoder 30 implemented by the logic circuit may include an image buffer (implemented by the processing unit 2820 or the memory 44) and a graphics processing unit.
  • the graphics processing unit may be communicatively coupled to the image buffer.
  • the graphics processing unit may include a decoder 30 implemented by a logic circuit 47 to implement the various modules discussed with reference to FIG. 3 and/or any other decoder systems or subsystems described herein.
  • antenna 42 may be used to receive an encoded bitstream of video data.
  • the encoded bitstream may include data, indicators, index values, mode selection data, etc., related to the encoded video frame discussed herein, such as data related to coded partitions (e.g., transform coefficients or quantized transform coefficients). , (As discussed) optional indicators, and/or data defining code partitions).
  • the video coding system 40 may also include a decoder 30 coupled to the antenna 42 and used to decode the encoded bitstream.
  • the display device 45 is used to present video frames.
  • the decoder 30 may be used to perform the reverse process.
  • the decoder 30 can be used to receive and parse such syntax elements, and decode related video data accordingly.
  • the encoder 20 may entropy encode the syntax elements into an encoded video bitstream. In such instances, the decoder 30 can parse such syntax elements and decode related video data accordingly.
  • the method described in the embodiment of the present application is mainly used in the image division process in video encoding. This process exists in both the encoder 20 and the decoder 30.
  • the encoder 20 and the decoder 30 in the embodiment of the present application can It is an encoder/decoder corresponding to video standard protocols such as H.263, H.264, HEVV, MPEG-2, MPEG-4, VP8, VP9, or next-generation video standard protocols (such as H.266, etc.).
  • FIG. 2 shows a schematic/conceptual structural block diagram of an example of an encoder 20 used to implement an embodiment of the present application.
  • the encoder 20 includes a residual calculation unit 204, a transformation processing unit 206, a quantization unit 208, and an inverse A quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a buffer 216, a loop filter unit 220, a decoded picture buffer (DPB) 230, a prediction processing unit 260, and an entropy coding unit 270.
  • the prediction processing unit 260 may include an inter prediction unit 244, an intra prediction unit 254, and a mode selection unit 262.
  • the inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown).
  • the encoder 20 shown in FIG. 2 may also be referred to as a hybrid video encoder or a video encoder according to a hybrid video codec.
  • the residual calculation unit 204, the transform processing unit 206, the quantization unit 208, the prediction processing unit 260, and the entropy encoding unit 270 form the forward signal path of the encoder 20, and for example, the inverse quantization unit 210, the inverse transform processing unit 212, and the The structure unit 214, the buffer 216, the loop filter 220, the decoded picture buffer (DPB) 230, and the prediction processing unit 260 form the backward signal path of the encoder, wherein the backward signal path of the encoder corresponds to The signal path of the decoder (see decoder 30 in FIG. 3).
  • the encoder 20 receives the picture 201 or the image block 203 of the picture 201 through, for example, an input 202, for example, a picture in a picture sequence that forms a video or a video sequence.
  • the image block 203 may also be called the current picture block or the picture block to be encoded
  • the picture 201 may be called the current picture or the picture to be encoded (especially when the current picture is distinguished from other pictures in video encoding, the other pictures are for example the same video sequence). That is, the previous coded and/or decoded picture in the video sequence that also includes the current picture).
  • the embodiment of the encoder 20 may include a segmentation unit (not shown in FIG. 2) for segmenting the picture 201 into a plurality of blocks such as the image block 203, usually into a plurality of non-overlapping blocks.
  • the segmentation unit can be used to use the same block size and the corresponding grid defining the block size for all pictures in the video sequence, or to change the block size between pictures or subsets or groups of pictures, and divide each picture into The corresponding block.
  • the prediction processing unit 260 of the encoder 20 may be used to perform any combination of the aforementioned segmentation techniques.
  • the image block 203 is also or can be regarded as a two-dimensional array or matrix of sampling points with sample values, although its size is smaller than that of the picture 201.
  • the image block 203 may include, for example, one sampling array (for example, a luminance array in the case of a black-and-white picture 201) or three sampling arrays (for example, one luminance array and two chrominance arrays in the case of a color picture) or Any other number and/or type of array depending on the color format applied.
  • the number of sampling points in the horizontal and vertical directions (or axes) of the image block 203 defines the size of the image block 203.
  • the encoder 20 shown in FIG. 2 is used to encode the picture 201 block by block, for example, to perform encoding and prediction on each image block 203.
  • the residual calculation unit 204 is configured to calculate the residual block 205 based on the picture image block 203 and the prediction block 265 (other details of the prediction block 265 are provided below), for example, by subtracting the sample value of the picture image block 203 sample by sample (pixel by pixel). The sample value of the block 265 is de-predicted to obtain the residual block 205 in the sample domain.
  • the transform processing unit 206 is configured to apply a transform such as discrete cosine transform (DCT) or discrete sine transform (DST) on the sample values of the residual block 205 to obtain transform coefficients 207 in the transform domain.
  • a transform such as discrete cosine transform (DCT) or discrete sine transform (DST)
  • DCT discrete cosine transform
  • DST discrete sine transform
  • the transform coefficient 207 may also be referred to as a transform residual coefficient, and represents the residual block 205 in the transform domain.
  • the transform processing unit 206 may be used to apply an integer approximation of DCT/DST, such as the transform specified for HEVC/H.265. Compared with the orthogonal DCT transform, this integer approximation is usually scaled by a factor. In order to maintain the norm of the residual block processed by the forward and inverse transformation, an additional scaling factor is applied as part of the transformation process.
  • the scaling factor is usually selected based on certain constraints. For example, the scaling factor is a trade-off between the power of 2 used for the shift operation, the bit depth of the transform coefficient, accuracy, and implementation cost.
  • the inverse transformation processing unit 212 for the inverse transformation designate a specific scaling factor, and accordingly, the encoder The 20 side uses the transformation processing unit 206 to specify a corresponding scaling factor for the positive transformation.
  • the quantization unit 208 is used to quantize the transform coefficient 207 by applying scalar quantization or vector quantization, for example, to obtain the quantized transform coefficient 209.
  • the quantized transform coefficient 209 may also be referred to as a quantized residual coefficient 209.
  • the quantization process can reduce the bit depth associated with some or all of the transform coefficients 207. For example, n-bit transform coefficients can be rounded down to m-bit transform coefficients during quantization, where n is greater than m.
  • the degree of quantization can be modified by adjusting the quantization parameter (QP). For example, for scalar quantization, different scales can be applied to achieve finer or coarser quantization.
  • QP quantization parameter
  • a smaller quantization step size corresponds to a finer quantization
  • a larger quantization step size corresponds to a coarser quantization.
  • the appropriate quantization step size can be indicated by QP.
  • the quantization parameter may be an index of a predefined set of suitable quantization steps.
  • a smaller quantization parameter can correspond to fine quantization (smaller quantization step size)
  • a larger quantization parameter can correspond to coarse quantization (larger quantization step size)
  • Quantization may include division by a quantization step size and corresponding quantization or inverse quantization performed by, for example, inverse quantization 210, or may include multiplication by a quantization step size.
  • Embodiments according to some standards such as HEVC may use quantization parameters to determine the quantization step size.
  • the quantization step size can be calculated based on the quantization parameter using a fixed-point approximation of an equation including division. Additional scaling factors can be introduced for quantization and inverse quantization to restore the norm of the residual block that may be modified due to the scale used in the fixed-point approximation of the equations for the quantization step size and the quantization parameter.
  • the scales of inverse transform and inverse quantization may be combined.
  • a custom quantization table can be used and signaled from the encoder to the decoder in, for example, a bitstream. Quantization is a lossy operation, where the larger the quantization step, the greater the loss.
  • the inverse quantization unit 210 is configured to apply the inverse quantization of the quantization unit 208 on the quantized coefficients to obtain the inverse quantized coefficients 211, for example, based on or use the same quantization step size as the quantization unit 208, and apply the quantization scheme applied by the quantization unit 208 The inverse quantification scheme.
  • the inversely quantized coefficient 211 may also be referred to as the inversely quantized residual coefficient 211, which corresponds to the transform coefficient 207, although the loss due to quantization is usually different from the transform coefficient.
  • the inverse transform processing unit 212 is used to apply the inverse transform of the transform applied by the transform processing unit 206, for example, DCT or DST, to obtain the inverse transform block 213 in the sample domain.
  • the inverse transformation block 213 may also be referred to as an inverse transformation and inverse quantization block 213 or an inverse transformation residual block 213.
  • the reconstruction unit 214 (for example, the summer 214) is used to add the inverse transform block 213 (that is, the reconstructed residual block 213) to the prediction block 265 to obtain the reconstructed block 215 in the sample domain, for example, The sample value of the reconstructed residual block 213 and the sample value of the prediction block 265 are added.
  • the buffer unit 216 (or “buffer” 216 for short) such as the line buffer 216 is used to buffer or store the reconstructed block 215 and the corresponding sample value, for example, for intra prediction.
  • the encoder can be used to use the unfiltered reconstructed block and/or the corresponding sample value stored in the buffer unit 216 to perform any type of estimation and/or prediction, such as intra-frame prediction.
  • the embodiment of the encoder 20 may be configured such that the buffer unit 216 is used not only for storing the reconstructed block 215 for intra prediction 254, but also for the loop filter unit 220 (not shown in FIG. 2 Out), and/or, for example, the buffer unit 216 and the decoded picture buffer unit 230 form one buffer.
  • Other embodiments may be used to use the filtered block 221 and/or blocks or samples from the decoded picture buffer 230 (neither shown in FIG. 2) as the input or basis for the intra prediction 254.
  • the loop filter unit 220 (or “loop filter” 220 for short) is used to filter the reconstructed block 215 to obtain the filtered block 221, thereby smoothly performing pixel conversion or improving video quality.
  • the loop filter unit 220 is intended to represent one or more loop filters, such as deblocking filters, sample-adaptive offset (SAO) filters or other filters, such as bilateral filters, auto Adaptive loop filter (ALF), or sharpening or smoothing filter, or collaborative filter.
  • the loop filter unit 220 is shown as an in-loop filter in FIG. 2, in other configurations, the loop filter unit 220 may be implemented as a post-loop filter.
  • the filtered block 221 may also be referred to as a filtered reconstructed block 221.
  • the decoded picture buffer 230 may store the reconstructed coded block after the loop filter unit 220 performs a filtering operation on the reconstructed coded block.
  • the embodiment of the encoder 20 may be used to output loop filter parameters (e.g., sample adaptive offset information), for example, directly output or by the entropy encoding unit 270 or any other
  • the entropy coding unit outputs after entropy coding, for example, so that the decoder 30 can receive and apply the same loop filter parameters for decoding.
  • the DPB 230 can be a reference picture memory that stores reference picture data for the encoder 20 to encode video data.
  • DPB 230 can be formed by any of a variety of memory devices, such as DRAM (including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM)) or other types Memory device.
  • DRAM including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM)
  • the DPB 230 and the buffer 216 may be provided by the same memory device or by separate memory devices.
  • the DPB 230 is used to store the filtered block 221.
  • the decoded picture buffer 230 may be further used to store other previous filtered blocks of the same current picture or different pictures such as the previously reconstructed picture, such as the previously reconstructed and filtered block 221, and may provide a complete previous Reconstruction is a decoded picture (and corresponding reference blocks and samples) and/or a partially reconstructed current picture (and corresponding reference blocks and samples), for example, for inter prediction.
  • the DPB 230 is used to store the reconstructed block 215.
  • the prediction processing unit 260 also called the block prediction processing unit 260, is used to receive or obtain the image block 203 (the current image block 203 of the current picture 201) and reconstructed picture data, such as the same (current) picture from the buffer 216
  • the reference samples and/or the reference picture data 231 of one or more previously decoded pictures from the decoded picture buffer 230, and used to process such data for prediction, that is, the provision can be an inter-predicted block 245 or a The prediction block 265 of the intra prediction block 255.
  • the mode selection unit 262 may be used to select a prediction mode (for example, intra or inter prediction mode) and/or the corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.
  • a prediction mode for example, intra or inter prediction mode
  • the corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.
  • the embodiment of the mode selection unit 262 can be used to select a prediction mode (for example, from those supported by the prediction processing unit 260) that provides the best match or minimum residual (the minimum residual means Better compression in transmission or storage), or provide minimal signaling overhead (minimum signaling overhead means better compression in transmission or storage), or consider or balance both.
  • the mode selection unit 262 may be configured to determine a prediction mode based on rate distortion optimization (RDO), that is, select a prediction mode that provides the smallest rate-distortion optimization, or select a prediction mode whose related rate-distortion at least meets the prediction mode selection criteria .
  • RDO rate distortion optimization
  • the encoder 20 is used to determine or select the best or optimal prediction mode from a set of (predetermined) prediction modes.
  • the prediction mode set may include, for example, an intra prediction mode and/or an inter prediction mode.
  • the set of intra prediction modes may include 35 different intra prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in H.265, or may include 67 Different intra-frame prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in H.266 under development.
  • the set of inter-frame prediction modes depends on the available reference pictures (ie, for example, the aforementioned at least part of the decoded pictures stored in the DBP230) and other inter-frame prediction parameters, such as whether to use the entire reference picture or only use A part of the reference picture, such as the search window area surrounding the area of the current block, to search for the best matching reference block, and/or depending on whether pixel interpolation such as half pixel and/or quarter pixel interpolation is applied.
  • the set of inter prediction modes may include, for example, an advanced motion vector prediction (AMVP) mode and a merge mode.
  • AMVP advanced motion vector prediction
  • the set of inter-frame prediction modes may include the improved AMVP mode based on control points in the embodiments of the present application, and the improved merge mode based on control points.
  • the intra prediction unit 254 may be used to perform any combination of inter prediction techniques described below.
  • the embodiments of the present application may also apply skip mode and/or direct mode.
  • the prediction processing unit 260 may be further used to divide the image block 203 into smaller block partitions or sub-blocks, for example, by iteratively using quad-tree segmentation, binary tree segmentation, or triple-tree (TT) segmentation, or any of them Combining, and for performing prediction for each of block partitions or sub-blocks, for example, where mode selection includes selecting a tree structure of divided image blocks 203 and selecting a prediction mode applied to each of the block partitions or sub-blocks.
  • quad-tree segmentation binary tree segmentation
  • TT triple-tree
  • the inter prediction unit 244 may include a motion estimation (ME) unit (not shown in FIG. 2) and a motion compensation (MC) unit (not shown in FIG. 2).
  • the motion estimation unit is used to receive or obtain the picture image block 203 (the current picture image block 203 of the current picture 201) and the decoded picture 231, or at least one or more previously reconstructed blocks, for example, one or more other/different
  • the reconstructed block of the previously decoded picture 231 is used for motion estimation.
  • the video sequence may include the current picture and the previously decoded picture 31, or in other words, the current picture and the previously decoded picture 31 may be part of the picture sequence forming the video sequence, or form the picture sequence.
  • the encoder 20 may be used to select a reference block from multiple reference blocks of the same or different pictures among multiple other pictures, and provide the reference picture and/or provide a reference to the motion estimation unit (not shown in FIG. 2)
  • the offset (spatial offset) between the position of the block (X, Y coordinates) and the position of the current block is used as an inter prediction parameter. This offset is also called a motion vector (MV).
  • the motion compensation unit is used to obtain inter prediction parameters, and perform inter prediction based on or using the inter prediction parameters to obtain the inter prediction block 245.
  • the motion compensation performed by the motion compensation unit may include fetching or generating a prediction block based on a motion/block vector determined by motion estimation (interpolation of sub-pixel accuracy may be performed). Interpolation filtering can generate additional pixel samples from known pixel samples, thereby potentially increasing the number of candidate prediction blocks that can be used to encode picture blocks.
  • the motion compensation unit 246 can locate the prediction block pointed to by the motion vector in a reference picture list.
  • the motion compensation unit 246 may also generate syntax elements associated with the blocks and video slices for use by the decoder 30 when decoding picture blocks of the video slices.
  • the aforementioned inter-prediction unit 244 may transmit syntax elements to the entropy encoding unit 270, and the syntax elements include inter-prediction parameters (for example, after traversing multiple inter-prediction modes and selecting the inter-prediction mode used for prediction of the current block) Instructions).
  • the inter-frame prediction parameter may not be carried in the syntax element.
  • the decoder 30 can directly use the default prediction mode for decoding. It can be understood that the inter prediction unit 244 may be used to perform any combination of inter prediction techniques.
  • the intra prediction unit 254 is used to obtain, for example, receive the picture block 203 (current picture block) of the same picture and one or more previously reconstructed blocks, for example reconstructed neighboring blocks, for intra estimation.
  • the encoder 20 may be used to select an intra prediction mode from a plurality of (predetermined) intra prediction modes.
  • the embodiment of the encoder 20 may be used to select an intra prediction mode based on optimization criteria, for example, based on a minimum residual (for example, an intra prediction mode that provides a prediction block 255 most similar to the current picture block 203) or a minimum rate distortion.
  • a minimum residual for example, an intra prediction mode that provides a prediction block 255 most similar to the current picture block 203
  • a minimum rate distortion for example, an intra prediction mode that provides a prediction block 255 most similar to the current picture block 203
  • the intra prediction unit 254 is further configured to determine the intra prediction block 255 based on the intra prediction parameters of the selected intra prediction mode. In any case, after selecting the intra prediction mode for the block, the intra prediction unit 254 is also used to provide intra prediction parameters to the entropy encoding unit 270, that is, to provide an indication of the selected intra prediction mode for the block Information. In one example, the intra prediction unit 254 may be used to perform any combination of intra prediction techniques.
  • the aforementioned intra-prediction unit 254 may transmit syntax elements to the entropy encoding unit 270, and the syntax elements include intra-prediction parameters (for example, after traversing multiple intra-prediction modes, selecting the intra-prediction mode used for prediction of the current block) Instructions).
  • the intra prediction parameter may not be carried in the syntax element.
  • the decoder 30 can directly use the default prediction mode for decoding.
  • the entropy coding unit 270 is used to apply entropy coding algorithms or schemes (for example, variable length coding (VLC) scheme, context adaptive VLC (context adaptive VLC, CAVLC) scheme, arithmetic coding scheme, context adaptive binary arithmetic) Coding (context adaptive binary arithmetic coding, CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding or other entropy Encoding method or technique) applied to quantized residual coefficients 209, inter-frame prediction parameters, intra-frame prediction parameters and/or loop filter parameters, one or all (or not applied), to obtain the output 272
  • VLC variable length coding
  • CAVLC context adaptive VLC
  • CABAC context adaptive binary arithmetic
  • SBAC syntax-based context-adaptive binary arithmetic coding
  • PIPE probability interval partitioning entropy
  • encoded picture data 21 output in the form of encoded bitstream
  • the encoded bitstream can be transmitted to the video decoder 30, or archived for later transmission or retrieval by the video decoder 30.
  • the entropy encoding unit 270 may also be used for entropy encoding other syntax elements of the current video slice being encoded.
  • the non-transform-based encoder 20 may directly quantize the residual signal without the transform processing unit 206 for certain blocks or frames.
  • the encoder 20 may have a quantization unit 208 and an inverse quantization unit 210 combined into a single unit.
  • the video encoder 20 may directly quantize the residual signal without being processed by the transform processing unit 206, and accordingly does not need to be processed by the inverse transform processing unit 212; or, for some For image blocks or image frames, the video encoder 20 does not generate residual data, and accordingly does not need to be processed by the transform processing unit 206, quantization unit 208, inverse quantization unit 210, and inverse transform processing unit 212; or, the video encoder 20 may The reconstructed image block is directly stored as a reference block without being processed by the filter 220; or, the quantization unit 208 and the inverse quantization unit 210 in the video encoder 20 may be combined together.
  • the loop filter 220 is optional, and for lossless compression coding, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, and the inverse transform processing unit 212 are optional. It should be understood that, according to different application scenarios, the inter prediction unit 244 and the intra prediction unit 254 may be selectively activated.
  • FIG. 3 shows a schematic/conceptual block diagram of an example of a decoder 30 for implementing an embodiment of the present application.
  • the video decoder 30 is used to receive, for example, encoded picture data (for example, an encoded bit stream) 21 encoded by the encoder 20 to obtain a decoded picture 231.
  • video decoder 30 receives video data from video encoder 20, such as an encoded video bitstream and associated syntax elements that represent picture blocks of an encoded video slice.
  • the decoder 30 includes an entropy decoding unit 304, an inverse quantization unit 310, an inverse transform processing unit 312, a reconstruction unit 314 (such as a summer 314), a buffer 316, a loop filter 320, and The decoded picture buffer 330 and the prediction processing unit 360.
  • the prediction processing unit 360 may include an inter prediction unit 344, an intra prediction unit 354, and a mode selection unit 362.
  • video decoder 30 may perform decoding passes that are substantially reciprocal of the encoding passes described with video encoder 20 of FIG. 2.
  • the entropy decoding unit 304 is configured to perform entropy decoding on the encoded picture data 21 to obtain, for example, quantized coefficients 309 and/or decoded encoding parameters (not shown in FIG. 3), for example, inter prediction, intra prediction parameters , Loop filter parameters and/or any one or all of other syntax elements (decoded).
  • the entropy decoding unit 304 is further configured to forward the inter prediction parameters, intra prediction parameters and/or other syntax elements to the prediction processing unit 360.
  • the video decoder 30 may receive syntax elements at the video slice level and/or the video block level.
  • the inverse quantization unit 310 can be functionally the same as the inverse quantization unit 110
  • the inverse transformation processing unit 312 can be functionally the same as the inverse transformation processing unit 212
  • the reconstruction unit 314 can be functionally the same as the reconstruction unit 214
  • the buffer 316 can be functionally identical.
  • the loop filter 320 may be functionally the same as the loop filter 220
  • the decoded picture buffer 330 may be functionally the same as the decoded picture buffer 230.
  • the prediction processing unit 360 may include an inter prediction unit 344 and an intra prediction unit 354.
  • the inter prediction unit 344 may be functionally similar to the inter prediction unit 244, and the intra prediction unit 354 may be functionally similar to the intra prediction unit 254.
  • the prediction processing unit 360 is generally used to perform block prediction and/or obtain a prediction block 365 from the encoded data 21, and to receive or obtain (explicitly or implicitly) prediction-related parameters and/or information about the prediction from the entropy decoding unit 304, for example. Information about the selected prediction mode.
  • the intra-prediction unit 354 of the prediction processing unit 360 is used for the intra-prediction mode based on the signal and the previous decoded block from the current frame or picture. Data to generate a prediction block 365 for the picture block of the current video slice.
  • the inter-frame prediction unit 344 eg, motion compensation unit
  • the other syntax elements generate a prediction block 365 for the video block of the current video slice.
  • a prediction block can be generated from a reference picture in a reference picture list.
  • the video decoder 30 can construct a list of reference frames: list 0 and list 1 based on the reference pictures stored in the DPB 330 using the default construction technique.
  • the prediction processing unit 360 is configured to determine prediction information for the video block of the current video slice by parsing the motion vector and other syntax elements, and use the prediction information to generate the prediction block for the current video block being decoded.
  • the prediction processing unit 360 uses some syntax elements received to determine the prediction mode (for example, intra or inter prediction) and the inter prediction slice type ( For example, B slice, P slice or GPB slice), construction information for one or more of the reference picture list for the slice, motion vector for each inter-coded video block of the slice, The inter prediction status and other information of each inter-encoded video block of the slice to decode the video block of the current video slice.
  • the syntax elements received by the video decoder 30 from the bitstream include receiving adaptive parameter set (APS), sequence parameter set (sequence parameter set, SPS), and picture parameter set (picture parameter set). parameter set, PPS) or a syntax element in one or more of the slice headers.
  • APS adaptive parameter set
  • SPS sequence parameter set
  • PPS picture parameter set
  • the inverse quantization unit 310 may be used to inverse quantize (ie, inverse quantize) the quantized transform coefficients provided in the bitstream and decoded by the entropy decoding unit 304.
  • the inverse quantization process may include using the quantization parameter calculated by the video encoder 20 for each video block in the video slice to determine the degree of quantization that should be applied and also determine the degree of inverse quantization that should be applied.
  • the inverse transform processing unit 312 is used to apply an inverse transform (for example, an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process) to transform coefficients so as to generate a residual block in the pixel domain.
  • an inverse transform for example, an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process
  • the reconstruction unit 314 (for example, the summer 314) is used to add the inverse transform block 313 (that is, the reconstructed residual block 313) to the prediction block 365 to obtain the reconstructed block 315 in the sample domain, for example by adding The sample value of the reconstructed residual block 313 and the sample value of the prediction block 365 are added.
  • the loop filter unit 320 (during the encoding cycle or after the encoding cycle) is used to filter the reconstructed block 315 to obtain the filtered block 321, thereby smoothly performing pixel transformation or improving video quality.
  • the loop filter unit 320 may be used to perform any combination of the filtering techniques described below.
  • the loop filter unit 320 is intended to represent one or more loop filters, such as deblocking filters, SAO filters or other filters, such as bilateral filters, ALF, or sharpening or smoothing filters, or collaborative filtering Device.
  • the loop filter unit 320 is shown as an in-loop filter in FIG. 3, in other configurations, the loop filter unit 320 may be implemented as a post-loop filter.
  • the decoded video block 321 in a given frame or picture is then stored in a decoded picture buffer 330 that stores reference pictures for subsequent motion compensation.
  • the decoder 30 is used, for example, to output the decoded picture 31 through the output 332 for presentation or viewing by the user.
  • the decoder 30 may generate an output video stream without the loop filter unit 320.
  • the non-transform-based decoder 30 may directly inversely quantize the residual signal without the inverse transform processing unit 312 for certain blocks or frames.
  • the video decoder 30 may have an inverse quantization unit 310 and an inverse transform processing unit 312 combined into a single unit.
  • the decoder 30 is used to implement the video decoding method described in the following embodiments.
  • the video decoder 30 may generate an output video stream without processing by the filter 320; or, for some image blocks or image frames, the entropy decoding unit 304 of the video decoder 30 does not decode the quantized coefficients, and accordingly does not It needs to be processed by the inverse quantization unit 310 and the inverse transform processing unit 312.
  • the loop filter 320 is optional; and for lossless compression, the inverse quantization unit 310 and the inverse transform processing unit 312 are optional.
  • the inter prediction unit and the intra prediction unit may be selectively activated.
  • the processing result for a certain link can be further processed and output to the next link, for example, in interpolation filtering, motion vector derivation or loop filtering, etc.
  • operations such as Clip or shift are further performed on the processing results of the corresponding link.
  • the motion vector of the control point of the current image block derived from the motion vector of the adjacent affine coding block, or the motion vector of the sub-block of the current image block derived from the motion vector may undergo further processing.
  • This application does not do this limited. For example, restrict the value range of the motion vector so that it is within a certain bit width. Assuming that the bit width of the allowed motion vector is bitDepth, the range of the motion vector is -2 bitDepth-1 to 2 bitDepth-1 -1. If bitDepth is 16, the value range is -32768 ⁇ 32767. If bitDepth is 18, the value range is -131072 ⁇ 131071.
  • the value of the motion vector (for example, the motion vector MV of the four 4 ⁇ 4 sub-blocks in an 8 ⁇ 8 image block) is restricted so that the integer parts of the four 4 ⁇ 4 sub-blocks MV
  • the maximum difference of does not exceed N pixels, for example, does not exceed one pixel.
  • FIG. 4 is a schematic structural diagram of a video decoding device 400 (such as a video encoding device 400 or a video decoding device 400) provided by an embodiment of the present application.
  • the video decoding device 400 is suitable for implementing the embodiments described herein.
  • the video coding device 400 may be a video decoder (for example, the decoder 30 of FIG. 1A) or a video encoder (for example, the encoder 20 of FIG. 1A).
  • the video coding device 400 may be one or more components of the decoder 30 in FIG. 1A or the encoder 20 in FIG. 1A described above.
  • the video decoding device 400 includes: an entrance port 410 and a receiver (Rx) 420 for receiving data, a processor 430, a logic unit or a central processing unit (CPU) for processing data, and a transmitter ( Tx) 440 and outlet port 450, and a memory 460 for storing data.
  • the video decoding device 400 may further include a photoelectric conversion component and an electro-optical (EO) component coupled with the inlet port 410, the receiver 420, the transmitter 440, and the outlet port 450 for the outlet or inlet of optical signals or electrical signals.
  • EO electro-optical
  • the processor 430 is implemented by hardware and software.
  • the processor 430 may be implemented as one or more CPU chips, cores (for example, multi-core processors), FPGA, ASIC, and DSP.
  • the processor 430 communicates with the ingress port 410, the receiver 420, the transmitter 440, the egress port 450, and the memory 460.
  • the processor 430 includes a decoding module 470 (for example, an encoding module 470 or a decoding module 470).
  • the encoding/decoding module 470 implements the embodiments disclosed herein to implement the video decoding method provided in the embodiments of the present application. For example, the encoding/decoding module 470 implements, processes, or provides various encoding operations.
  • the encoding/decoding module 470 provides a substantial improvement to the function of the video decoding device 400 and affects the conversion of the video decoding device 400 to different states.
  • the encoding/decoding module 470 is implemented by instructions stored in the memory 460 and executed by the processor 430.
  • the memory 460 includes one or more magnetic disks, tape drives, and solid-state hard disks, and can be used as an overflow data storage device for storing programs when these programs are selectively executed, and storing instructions and data read during program execution.
  • the memory 460 may be volatile and/or nonvolatile, and may be ROM, RAM, random access memory (TCAM), and/or SRAM.
  • FIG. 5 is a simplified block diagram of an apparatus 500 that can be used as either or both of the source device 12 and the destination device 14 in FIG. 1A according to an exemplary embodiment.
  • the device 500 can implement the technology of the present application.
  • FIG. 5 is a schematic block diagram of an implementation manner of an encoding device or a decoding device (referred to as a decoding device 500 for short) according to an embodiment of the application.
  • the decoding device 500 may include a processor 510, a memory 530, and a bus system 550.
  • the processor and the memory are connected through a bus system, the memory is used to store instructions, and the processor is used to execute instructions stored in the memory.
  • the memory of the decoding device stores program codes, and the processor can call the program codes stored in the memory to execute various video encoding or decoding methods described in this application. To avoid repetition, it will not be described in detail here.
  • the processor 510 may be a central processing unit (CPU), and the processor 510 may also be other general-purpose processors, DSPs, ASICs, FPGAs or other programmable logic devices, discrete gates. Or transistor logic devices, discrete hardware components, etc.
  • the general-purpose processor may be a microprocessor or the processor may also be any conventional processor or the like.
  • the memory 530 may include a ROM device or a RAM device. Any other suitable type of storage device can also be used as the memory 530.
  • the memory 530 may include code and data 531 accessed by the processor 510 using the bus 550.
  • the memory 530 may further include an operating system 533 and an application program 535.
  • the application program 535 includes at least one program that allows the processor 510 to execute the video encoding or decoding method described in this application (especially the video decoding method described in this application).
  • the application program 535 may include applications 1 to N, which further include a video encoding or decoding application (referred to as a video coding application) that executes the video encoding or decoding method described in this application.
  • the bus system 550 may also include a power bus, a control bus, and a status signal bus. However, for clear description, various buses are marked as the bus system 550 in the figure.
  • the decoding device 500 may further include one or more output devices, such as a display 570.
  • the display 570 may be a touch-sensitive display that merges the display with a touch-sensitive unit operable to sense touch input.
  • the display 570 may be connected to the processor 510 via the bus 550.
  • any one of the source device 12 and the destination device 14 shown in FIG. 1A, the video encoding system 40 shown in FIG. 1B, and the video decoding device described in FIG. 4 and FIG. 5 can adopt QT in the video encoding process.
  • QT is a tree structure, which means that a node can be divided into four sub-nodes.
  • the existing video coding standard adopts a quadtree-based CTU division method: CTU is the root node, and each node corresponds to a square area; a node can no longer be divided (in this case, its corresponding area is a CU), or This node is divided into four nodes of the next level, that is, the square area is divided into four square areas of the same size (the length and width are each half the length and width of the area before division), and each area corresponds to a node , As shown in Figure 6 (a).
  • BT is a tree structure, which means that a node can be divided into two child nodes.
  • a node on a binary tree structure may not be divided, or the node may be divided into two nodes of the next level.
  • EQT is a kind of I-word division structure, a node can be divided into four sub-nodes.
  • the H.265 video coding standard divides a frame of image into non-overlapping coding tree units (CTU).
  • the size of the CTU can be set to 64 ⁇ 64 (the size of the CTU can also be set to other values, such as the CTU in the JVET reference software JEM The size is increased to 128 ⁇ 128 or 256 ⁇ 256).
  • a 64 ⁇ 64 CTU contains a rectangular pixel matrix with 64 columns and 64 pixels in each column, and each pixel contains a luminance component or/and a chrominance component.
  • QT's CTU division method CTU is regarded as the root node of the quadtree, and the CTU is recursively divided into several leaf nodes according to the quadtree division method.
  • a node corresponds to an image area.
  • the node is called a leaf node, and its corresponding image area forms a CU; if the node continues to be divided, the image area corresponding to the node is divided into four areas of the same size (its The length and width are each half of the divided area), each area corresponds to a node, and it is necessary to determine whether these nodes will still be divided.
  • whether a node is divided is indicated by the split_cu_flag corresponding to the node in the code stream.
  • the quadtree level (qtDepth) of the root node is 0, and the quadtree level of the node is the quadtree level of the parent node of the node plus 1.
  • the size and shape of the node below refer to the size and shape of the image area corresponding to the node.
  • the minimum size (size) of the CU is identified in the sequence parameter set (Sequence Parameter Set, SPS), for example, 8 ⁇ 8 is the smallest CU.
  • SPS Sequence Parameter Set
  • the leaf node When a node is parsed as a leaf node, the leaf node is a CU, and the decoding end device further analyzes the coding information corresponding to the CU (including the prediction mode and transform coefficients of the CU, such as the coding_unit() syntax structure in H.265 Then, according to the coding information, the CU is subjected to decoding processing such as prediction, inverse quantization, inverse transformation, and loop filtering, to generate a reconstructed image corresponding to this CU.
  • the quad-tree structure enables the CTU to be divided into a group of CUs of appropriate size according to the local characteristics of the image, for example, the smooth area is divided into larger CUs, and the texture rich area is divided into smaller CUs.
  • VTM video coding test model
  • BT binary tree
  • TT ternary tree
  • FIG. 7 shows an example of using QT-MTT to divide a CTU into 16 CUs ranging from a to p.
  • each end point represents a node
  • a node connected with 4 lines represents quadtree division
  • a node connected with 2 lines represents binary tree division
  • a node connected with 3 lines represents trigeminal tree division.
  • the solid line represents QT division
  • the dashed line represents the first level division of Multi-Type Tree (MTT)
  • the dotted line represents the second level division of MTT.
  • a to p are 16 MTT leaf nodes, and each MTT leaf node is 1 CU.
  • a CTU obtains the CU division diagram shown in the left diagram of FIG. 7 according to the division method of the right diagram in FIG. 7.
  • each CU has a QT level (quad-tree depth, QT depth, also called QT depth) and an MTT level (multi-type tree depth, MTT depth, also called MTT depth).
  • QT level represents the QT level of the QT leaf node to which the CU belongs
  • MTT level represents the MTT level of the MTT leaf node to which the CU belongs.
  • the QT level of the root node of the coding tree is 0, and the MTT level is 0.
  • the QT level of the sub-node obtained by division is the QT level of the node plus 1, and the MTT level remains unchanged; similarly, if a node on the coding tree uses MTT division (ie BT or TT) Division 1), the MTT level of the child node obtained by division is the MTT level of the node plus 1, and the QT level remains unchanged.
  • MTT division ie BT or TT
  • the QT level of a, b, c, d, e, f, g, i, and j is 1, and the MTT level is 2; the QT level of h is 1, and the MTT level is 1; n, o, p The QT level is 2, and the MTT level is 0; the QT level of l and m is 2, and the MTT level is 1. If the CTU is divided into only one CU, the QT level of this CU is 0, and the MTT level is 0.
  • AVS3 uses the QT cascaded BT/EQT division method, that is, the nodes on the first-level coding tree can only be divided into sub-nodes using QT, and the leaf nodes of the first-level coding tree are the root nodes of the second-level coding tree;
  • the nodes on the second-level coding tree can be divided into sub-nodes using one of BT or EQT division methods; the leaf nodes of the second-level coding tree are coding units. It should be noted that when the leaf node is divided into BT or EQT, its leaf node can only use the BT or EQT division, but not the QT.
  • Video coding mainly includes intra prediction (Intra Prediction), inter prediction (Inter Prediction), transformation (Transform), and quantization (Quantization). ), entropy encoding, in-loop filtering (mainly de-blocking filtering) and other links.
  • intra prediction Intra Prediction
  • Inter Prediction inter prediction
  • Transform transformation
  • quantization Quantization
  • entropy encoding in-loop filtering (mainly de-blocking filtering) and other links.
  • the encoding block is an M ⁇ N array (M may be equal to N or not equal to N) composed of pixels, and the pixel value of each pixel point is known.
  • Intra-frame prediction refers to predicting the pixel value of the pixel in the current coding block by using the pixel value of the pixel in the reconstructed area in the current image.
  • Inter-frame prediction is to find a matching reference block for the current coding block in the current image in the reconstructed image, so as to obtain the motion information of the current coding block, and then calculate the pixel value of the pixels in the current coding block according to the motion information Predicted information or predicted value (the following will no longer distinguish between information and value).
  • the process of calculating motion information is called motion estimation (ME)
  • the process of calculating the predicted value of the pixel value of the pixel in the current encoding block is called motion compensation (MC).
  • the motion information of the current coding block includes the indication information of the prediction direction (usually forward prediction, backward prediction or bidirectional prediction), one or two motion vectors (MV) pointing to the reference block, And the indication information of the image where the reference block is located (usually recorded as the reference frame index, Reference index).
  • Forward prediction means that the current coding block selects a reference image from the forward reference image set to obtain a reference block.
  • Backward prediction means that the current coding block selects a reference image from the backward reference image set to obtain a reference block.
  • Bidirectional prediction refers to selecting a reference image from a set of forward and backward reference images to obtain a reference block. When the bidirectional prediction method is used, there will be two reference blocks in the current coding block, and each reference block needs a motion vector and a reference frame index to indicate, and then the pixel in the current block is determined according to the pixel value of the pixel in the two reference blocks The predicted value of the pixel value.
  • the motion estimation process needs to try multiple reference blocks in the reference image for the current coding block, and which one or several reference blocks are finally used for prediction is determined by rate-distortion optimization (Rate-distortion optimization, RDO) or other methods.
  • rate-distortion optimization RDO
  • the prediction information is obtained by using intra prediction or inter prediction
  • the pixel value of the pixel in the current coding block is subtracted from the corresponding prediction information to obtain the residual information, and then the residual information is obtained by using discrete cosine transform (DCT) and other methods.
  • DCT discrete cosine transform
  • the difference information is transformed, and then quantized entropy coding is used to obtain the code stream.
  • the prediction signal is added to the reconstructed residual signal, a further filtering operation is required to obtain the reconstructed signal and use it as a reference signal for subsequent coding.
  • Decoding is equivalent to the reverse process of encoding. For example, first use entropy decoding inverse quantization and inverse transformation to obtain residual information, and decode the code stream to determine whether the current coding block uses intra prediction or inter prediction. If it is intra-frame prediction, the pixel values of pixels in the surrounding reconstructed area are used to construct prediction information according to the intra-frame prediction method used. If it is inter-frame prediction, it is necessary to analyze the motion information, and use the resolved motion information to determine the reference block in the reconstructed image, and use the pixel value of the pixel in the block as the prediction information. This process is called motion compensation (Motion compensation, MC).
  • the reconstruction information can be obtained by filtering operation using prediction information plus residual information.
  • this application provides an image division method, which is applied to the video encoding (including encoding and decoding) process.
  • the method can be used by the source device 12, the destination device 14, the video encoder 20, the video decoder 30, and the video decoding device. 400 or the video decoding device 500 executes.
  • the method mainly includes the following steps:
  • the current image block may be an image block divided from the current image, corresponding to a node on the coding tree of the current image, and the current image block may also be an LCU of the current image (for example, CTU in the HEVC standard), It may also be a sub-block obtained by dividing an LCU as a root node, or a sub-block obtained by dividing a sub-block of a certain level as a root node.
  • LCU of the current image for example, CTU in the HEVC standard
  • the block information of the current image block may include size information of the current image block, such as the width of the current image block, the height of the current image block, or the area obtained based on the width and height of the current image block.
  • the block information of the current image block may also include the coordinates of the pixels in the current image block, for example, the coordinates of the pixels in the current image block in the image coordinate system, where the origin of the image coordinate system is the upper left corner of the image where the current image block is located.
  • the horizontal axis of the image coordinate system is the width direction (x axis) of the image where the current image block is located
  • the vertical axis of the image coordinate system is the height direction (y axis) of the image where the current image block is located.
  • the block information of the current image may also include other image-related information corresponding to the current image block, for example, whether the current image block exceeds the boundary of the current image, for the video decoder device, the block information can be parsed from the code stream of the current image Or derived.
  • the following methods can be used to determine whether the current image block exceeds the boundary of the image where the current image block is located: obtain the coordinates (x, y) of a pixel in the current image block according to the block information of the image block; determine the coordinates of the pixel point Whether (x, y) meets the preset condition, if the coordinate (x, y) of the pixel meets the first preset condition, it means that the current image block is out of the right boundary of the image where the current image block is located. If the coordinate of the pixel (x , Y) If the second preset condition is met, it indicates that the image block exceeds the lower boundary of the image where the current image block is located.
  • the coordinates (x, y) of the pixel meet the third preset condition, it indicates that the current image block exceeds the current image block The right boundary of the image where it is and exceeds the lower boundary of the current image (referred to as the lower right boundary). If the coordinates (x, y) of the pixel meet the fourth preset condition, it indicates that the current image block exceeds the boundary of the image where the current image block is located. That is, the picture may exceed the lower border of the image, or the right border of the image, or the lower right border of the image.
  • the first preset condition is: pixel point The coordinates (x, y) satisfy x+width>PicWidth, and y+height ⁇ PicHeight;
  • the second preset condition is: the coordinates (x,y) of the pixel point satisfy x+width ⁇ PicWidth, and y+height>PicHeight ;
  • the third preset condition is: the coordinate (x, y) of the pixel meets x+width>PicWidth, and y+height>PicHeight;
  • the fourth preset condition is: the coordinate (x, y) of the pixel meets x+ width>PicWidth, or y+height>PicHeight.
  • width is the width of the current image block
  • S802 According to the obtained block information, determine an available division mode from the set of candidate division modes.
  • the set of candidate partitioning methods includes, but is not limited to, no partitioning method, horizontal binary tree HBT partitioning method, vertical binary tree VBT partitioning method, horizontally expanding quadtree HEQT partitioning method, vertically expanding quadtree VEQT partitioning method, and quadtree QT partitioning method One or more of.
  • S803 Determine the division mode of the current image block from the determined available division modes.
  • the current image block division method can be determined from the determined available division methods in the following way: when there is one available division method, the available division method is determined as the current image block division method; When there are multiple division modes, the code stream including the current image block is analyzed according to the determined available division mode, and the division mode of the current image block is determined according to the analysis result.
  • the available division method is determined by comparing the size of the current image block with the division constraint condition corresponding to each candidate division method. If the size of the current image block meets the division constraint condition corresponding to the candidate division method, the The candidate partition mode is available. If the QT division method is available and all the division methods except the QT division method in the candidate division method set are not available, the current image block division method is the QT division method. If the QT division mode is available, and at least one division mode other than the QT division mode in the candidate division mode set is available, the code stream is parsed to determine the division mode of the current image block.
  • the division mode of the current image block is the non-divided mode. If the undivided mode is available, and at least one division mode other than the non-divided mode and the QT division mode in the candidate division mode set is available, the code stream is parsed to determine the division mode of the current image block.
  • the decoding device parses the binary tree extended quadtree division flag bet_split_flag from the code stream.
  • the value of bet_split_flag is 1 indicates that the binary tree extended quadtree division should be used for image division, and the value 0 indicates that the binary tree extended quadtree row division should not be performed. . If the value of bet_split_flag is 1, continue to parse the flag bet_split_type_flag that indicates the division type of the current image block.
  • the value of bet_split_type_flag is 0, which means that the BT division method should be used when the binary tree is expanded, and the value of 1 means the binary tree is expanded.
  • the EQT division method should be used when dividing; the flag bet_split_dir_flag used to indicate the division direction of the current image block is analyzed.
  • the value of bet_split_dir_flag is 1 to indicate that the binary tree expansion quadtree should be divided by vertical division, and the value 0 indicates that the binary tree is expanded quadtree. Use horizontal division when dividing the tree.
  • the current image block division method can be determined from the determined available division methods in the following manner: when there is one available division method, the available division method is determined as the current image block division method; When there are multiple division methods, the rate-distortion cost of each available division method is determined separately, and the available division method with the smallest rate-distortion cost among the available division methods is determined as the current image block division method.
  • S804 Obtain one or more CUs from the current image block according to the division mode of the current image block. Among them, the aspect ratio of each CU meets the set maximum aspect ratio of the CU.
  • the current image block when the current image block is divided into non-divided mode, the current image block is a CU; when the current image block is divided into any division mode other than the non-divided mode, the current image block is divided according to the current divided mode.
  • the image block is divided. If at least one side length of the divided sub-block is T and T is 4 or 8, then the sub-block is a CU. Otherwise, repeat the above steps S802 and S803 for this sub-block, continue to determine the division method, and change
  • the current image block is recursively divided into multiple CUs. Further, the maximum aspect ratio of the set CU may be 4 or 8.
  • an available partitioning method is determined from a set of candidate partitioning methods, including but not limited to one or more of the following methods:
  • Manner 1 According to the block information, it is determined whether the current image block meets the first condition, and when the current image block meets the first condition, it is determined that the VBT division mode is an available division mode.
  • the first condition is width>height*MaxPartRatio
  • width is the width of the current image block
  • height is the height of the current image block
  • MaxPartRatio is the maximum aspect ratio of the set CU. It should be noted that "*" in the embodiment of the present application represents multiplication.
  • this application relaxes the conditions for using the VBT division method.
  • the VBT division method can be adopted . In order to avoid the appearance of image blocks whose aspect ratio does not meet the set maximum CU aspect ratio (image blocks that must be divided but cannot be divided), and the coding performance is improved.
  • Manner 2 Determine whether the current image block meets the second condition according to the block information; when the current image block meets the second condition, determine that the HBT division mode is an available division mode.
  • the second condition is height>width*MaxPartRatio
  • width is the width of the current image block
  • height is the height of the current image block
  • MaxPartRatio is the maximum aspect ratio of the set CU.
  • this application relaxes the conditions for using the HBT division method.
  • the HBT division method can be adopted . In order to avoid the appearance of image blocks whose aspect ratio does not meet the set maximum CU aspect ratio (image blocks that must be divided but cannot be divided), and the coding performance is improved.
  • Manner 3 Determine whether the current image block meets the conditions in the first condition set according to the block information; when the current image block meets all the conditions in the first condition set, determine that the VEQT division mode is an available division mode.
  • the first condition set includes the following conditions: (1) width ⁇ MaxEqtSize; (2) height ⁇ MaxEqtSize; (3) height ⁇ MinEqtSize*2; (4) width ⁇ MinEqtSize*4; (5) height*4 ⁇ MaxPartRatio *width; (6) height*MaxPartRatio ⁇ width; where width is the width of the current image block, height is the height of the current image block, MaxEqtSize is the size of the maximum EQT set, and MinEqtSize is the size of the minimum EQT set. MaxPartRatio is the maximum aspect ratio of the set CU.
  • this application tightens the conditions for using the VEQT division method to try to avoid image blocks with an aspect ratio that does not meet the set maximum CU aspect ratio (images that must be divided but cannot be divided) Block) to improve coding performance.
  • the second condition set includes the following conditions: (1) width ⁇ MaxEqtSize; (2) height ⁇ MaxEqtSize; (3)width ⁇ MinEqtSize*2; (4)height ⁇ MinEqtSize*4; (5)width*4 ⁇ MaxPartRatio *height; (7) width*MaxPartRatio ⁇ height; where width is the width of the current image block, heigh is the height of the current image block, MaxEqtSize is the maximum EQT size, MinEqtSize is the minimum EQT size, and MaxPartRatio is the maximum width of the CU High ratio.
  • this application tightens the conditions for using the HEQT division method to try to avoid the appearance of image blocks whose aspect ratio does not meet the set maximum CU aspect ratio (images that must be divided but cannot be divided) Block) to improve coding performance.
  • the current image block before judging whether the current image block satisfies the corresponding condition (or condition set), it is necessary to determine the current image block in the image where the current image block is located according to the block information of the current image block. Within the boundary. Specifically, it can be determined that the current image block is within the boundary of the current image block by the following steps: determine whether the current image block meets the third condition according to the block information of the current image block; when the current image block meets the third condition, determine The current image block is within the boundary of the current image block.
  • the third condition is: (x0+width) ⁇ PicWidth, and (y0+height) ⁇ PicHeight
  • x0 is the abscissa of the pixel of the upper left vertex of the current image block in the image coordinate system
  • y0 is the current image in the image coordinate system
  • the ordinate of the pixel of the upper left vertex of the block, the origin of the image coordinate system is the pixel of the upper left vertex of the image where the current image block is located
  • the horizontal axis of the image coordinate system is the width direction of the image where the current image block is located
  • the image coordinate system The vertical axis of is the height direction of the image where the current image block is located
  • PicWidth is the width of the image where the current image block is located
  • PicHeight is the height of the image where the current image block is located, as shown in FIG. 9.
  • the above methods 1 to 5 can be implemented by the coding tree definition syntax shown in Table 2.
  • Table 2 mainly shows the different parts of the coding tree definition used in the prior art, and other parts You can refer to the coding tree definition syntax shown in Table 1.
  • the methods in the prior art can be used to determine the available division methods in the set of candidate divisible methods. For example, when the current image block exceeds the boundary of the image where the current image block is located, The coding tree definition syntax shown in Table 1 can be used to determine whether the available partitioning methods in the set of candidate partitioning methods are available.
  • MaxBTSize and MaxEqtSize are set to less than 64, according to the existing coding tree definition grammar, the N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image obtained by the boundary LCU division will not be able to continue to be divided, from the greater impact to the encoding performance.
  • MaxBTSize and MaxEqtSize are set to 8
  • the 16x64 block generated by dividing in the boundary CTU cannot continue to be divided, for example, the 64x64 block generated by BT division in the boundary LCU cannot be divided continuously.
  • the image division method provided in this application also includes determining that the current image block exceeds the boundary of the image where the current image block is located according to the block information of the current image block, and according to the block information of the current image block, the set maximum BT To determine whether the QT division method is an available division method.
  • the following method can be used to determine that the current image block exceeds the boundary of the image where the current image block is located: judging whether the current image block meets the fourth condition according to the block information of the current image block; when the current image block meets the fourth condition, Determine that the current image block exceeds the boundary of the current image block.
  • the fourth condition is: (x0+width)>PicWidth, and (y0+height)>PicHeight
  • x0 is the abscissa of the pixel point of the upper left vertex of the current image block in the image coordinate system
  • y0 is the current image in the image coordinate system
  • the ordinate of the pixel of the upper left vertex of the block, the origin of the image coordinate system is the pixel of the upper left vertex of the image where the current image block is located
  • the horizontal axis of the image coordinate system is the width direction of the image where the current image block is located
  • the image coordinate system The vertical axis of is the height direction of the image where the current image block is located
  • PicWidth is the width of the image where the current image block is located
  • PicHeight is the height of the image where the current image block is located.
  • the QT division method is an available division method by any of the following methods:
  • Method A Determine whether the current image block satisfies the condition in the third condition set according to the block information of the image block; if the current image block satisfies at least one condition in the third condition set, the QT division mode is an available division mode.
  • the third condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; width is the width of the current image block, heigh is the height of the current image block, MaxBTSize is the size of the set maximum BT, MaxEqtSize is the size of the maximum EQT set, and max(
  • Method B According to the block information of the image block, it is determined whether the current image block meets the conditions in the fourth condition set; if the current image block meets at least one condition in the fourth condition set, the QT division mode is an available division mode.
  • the fourth condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width >MaxEqtSize, height>MaxBTSize, and height>MaxEqtSize; (4) width>max(MaxBTSize, MaxEqtSize); (5) height>max(MaxBTSize, MaxEqtSize); (6) width>max(MaxBTSize, MaxEqtSize), and height >max(MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; (11) the current image block does not exceed the right of the image where the image block is located The boundary, and does not exceed the lower boundary of the image where the image block is located, that is, the current image block exceeds the lower right boundary of the image where the
  • the QT division method is adopted to avoid dividing the boundary image block into N ⁇ 64 or 64 ⁇ N (N ⁇ 64) Therefore, when MaxBTSize and MaxEqtSize are set to less than 64, the problem that N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image blocks cannot be divided can be avoided. That is to say, in the image division process, when the current image block exceeds the boundary of the image where the image block is located, when the current image block satisfies any one of the above-mentioned third condition set or the fourth condition set, the candidate division method set Except for the QT division method, other division methods are not available.
  • the current image can only use the QT division method, it can avoid dividing the boundary image block to obtain N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image blocks, thereby avoiding When MaxBTSize and MaxEqtSize are set to be less than 64, the problem that N ⁇ 64 or 64 ⁇ N (N ⁇ 64) image blocks cannot continue to be divided.
  • the coding tree definition syntax shown in Table 3 can be used to implement;
  • the coding tree definition syntax shown in Table 4 can be used to implement;
  • the coding tree definition syntax shown in Table 5 can be used to implement;
  • the third condition set When the included condition is (9), or the conditions included in the fourth set of conditions are (9) and (11), the coding tree definition syntax shown in Table 6 can be used to implement.
  • Tables 3 to 6 mainly show parts that are different from the coding tree definition used in the prior art. For other parts, refer to the coding tree definition syntax shown in Table 1 or the coding tree definition syntax shown in Table 2.
  • MaxEqtSize is 2 M , where the value of M is 3, 4, 5, or 6.
  • the code stream containing the current image block can be analyzed to obtain the decoding information of each CU, and the CU can be decoded according to the decoding information to obtain a reconstructed block.
  • the decoding end device parses the syntax element of each CU from the code stream of the image where the current image block is located, obtains the prediction information and residual information of each CU, and performs inter-frame prediction processing or frame prediction on the CU according to the prediction mode of the CU. Intra-prediction processing to obtain the inter-frame prediction image or intra-frame prediction image of the CU.
  • the transform coefficients are subjected to inverse quantization and inverse transform processing to obtain the residual image, which is superimposed on the predicted image of the CU to obtain the reconstructed block of the CU.
  • the image block when the current image block is divided, the image block can be divided into one or more CUs that meet the set CU maximum aspect ratio, which can solve the problem of image division in the prior art. Due to the limitation of the maximum aspect ratio of the CU, the problem of image blocks that must be divided but cannot be divided occurs, which can improve the coding performance.
  • this application also provides another image division method, which is applied to the video encoding (including encoding and decoding) process. This method can be used by the source device 12, the destination device 14, and the video encoder 20.
  • the decoder 30, the video decoding device 400, or the video decoding device 500 executes. The method mainly includes the following steps:
  • the current image block may be an image block divided from the current image, corresponding to a node on the coding tree of the current image, and the current image block may also be an LCU of the current image (for example, CTU in the HEVC standard), It may also be a sub-block obtained by dividing an LCU as a root node, or a sub-block obtained by dividing a sub-block of a certain level as a root node.
  • LCU of the current image for example, CTU in the HEVC standard
  • the block information of the current image block may include size information of the current image block, such as the width of the current image block, the height of the current image block, or the area obtained based on the width and height of the current image block.
  • the block information of the current image block may also include the coordinates of the pixels in the current image block, for example, the coordinates of the pixels in the current image block in the image coordinate system, where the origin of the image coordinate system is the upper left corner of the image where the current image block is located.
  • the horizontal axis of the image coordinate system is the width direction (x axis) of the image where the current image block is located
  • the vertical axis of the image coordinate system is the height direction (y axis) of the image where the current image block is located.
  • the block information of the current image can also be other image-related information corresponding to the current image block, for example, whether the current image block exceeds the boundary of the current image.
  • the block information can be parsed from the current image code stream or Derived.
  • step S801 For a specific method for determining whether the current image block exceeds the boundary of the image where the current image block is located, reference may be made to the related description in step S801, which will not be repeated here.
  • S1002 According to the obtained block information, determine an available division mode from the set of candidate division modes. Among them, when the current image block exceeds the boundary of the image where the current image block is located, according to the block information of the current image block, the size of the set maximum BT, and the size of the set maximum EQT, it is determined whether the QT division mode in the candidate division mode set is It is an available division method.
  • the set of candidate division methods may also include, but are not limited to, one of non-division, horizontal binary tree HBT division, vertical binary tree VBT division, horizontal expansion quadtree HEQT division, and vertical expansion quadtree VEQT division. Or multiple.
  • the specific method for judging whether the QT division method is an available division method can refer to the related descriptions of the method A and the method B in the above-mentioned first image division method, which will not be repeated here.
  • S1003 Determine the division mode of the current image block from the determined available division modes.
  • step S803 the specific method for determining the division manner of the current image block can be referred to the relevant description in step S803, which will not be repeated here.
  • S1004 Obtain one or more CUs from the current image block according to the division mode of the current image block.
  • the current image block when the current image block is divided into non-divided mode, the current image block is a CU; when the current image block is divided into any division mode other than the non-divided mode, the current image block is divided according to the current divided mode.
  • the image block is divided. If at least one side length of the divided sub-block is T and T is 4 or 8, then the sub-block is a CU. Otherwise, repeat the above steps S1002 and S1003 for this sub-block, continue to determine the division method, change
  • the current image block is recursively divided into multiple CUs.
  • the code stream containing the current image block can also be parsed to obtain the decoding information of each CU, and the CU can be decoded according to the decoding information to obtain a reconstructed block.
  • the decoding end device parses the syntax element of each CU from the code stream of the image where the current image block is located, obtains the prediction information and residual information of each CU, and performs inter-frame prediction processing or frame prediction on the CU according to the prediction mode of the CU. Intra-prediction processing to obtain the inter-frame prediction image or intra-frame prediction image of the CU.
  • the transform coefficients are subjected to inverse quantization and inverse transform processing to obtain the residual image, which is superimposed on the predicted image of the CU to obtain the reconstructed block of the CU.
  • an embodiment of the present application also provides a video encoding device 1100.
  • the video encoding device 1100 includes: an obtaining unit 1101, a determining unit 1102, and a dividing unit 1103.
  • the video encoding device 1100 is used to implement the image division method as shown in FIG. 8, where:
  • the obtaining unit 1101 is configured to obtain block information of the current image block.
  • the determining unit 1102 is configured to determine an available division mode from the set of candidate division modes according to the block information obtained by the obtaining unit 1101; and, from the determined available division mode, determine the current image block division mode.
  • the dividing unit 1103 is configured to obtain one coding unit CU or multiple CUs from the current image block according to the dividing mode of the current image block determined by the determining unit 1102; wherein the aspect ratio of each CU meets the set maximum width of the CU High ratio.
  • the maximum aspect ratio of the set CU can be 4 or 8.
  • the set of candidate partitioning methods may include no partitioning method, horizontal binary tree HBT partitioning method, vertical binary tree VBT partitioning method, horizontally expanding quadtree HEQT partitioning method, vertically expanding quadtree VEQT partitioning method, and quadtree QT partitioning method.
  • horizontal binary tree HBT partitioning method vertical binary tree VBT partitioning method
  • horizontally expanding quadtree HEQT partitioning method vertically expanding quadtree VEQT partitioning method
  • quadtree QT partitioning method quadtree QT partitioning method.
  • the determining unit 1102 is specifically configured to determine whether the current image block satisfies the first condition according to the block information of the current image block; when the current image block satisfies the first condition, determine that the VBT division mode is an available division mode.
  • the first condition is width>height*MaxPartRatio
  • width is the width of the current image block
  • height is the height of the current image block
  • MaxPartRatio is the maximum aspect ratio of the set CU.
  • the determining unit 1102 is specifically configured to: determine whether the current image block meets the second condition according to the block information of the current image block; when the current image block meets the second condition, determine that the HBT division method is an available division method; where ,
  • the second condition is height>width*MaxPartRatio, width is the width of the current image block, height is the height of the current image block, and MaxPartRatio is the maximum aspect ratio of the set CU.
  • the determining unit 1102 is specifically configured to: determine whether the current image block meets the conditions in the first condition set according to the block information of the current image block; when the current image block meets all the conditions in the first condition set, determine VEQT
  • the division method is the available division method.
  • the first condition set includes the following conditions: (1) width ⁇ MaxEqtSize; (2) height ⁇ MaxEqtSize; (3) height ⁇ MinEqtSize*2; (4) width ⁇ MinEqtSize*4; (5) height*4 ⁇ MaxPartRatio *width; (6) height*MaxPartRatio ⁇ width; where width is the width of the current image block, height is the height of the current image block, MaxEqtSize is the size of the maximum EQT set, and MinEqtSize is the size of the minimum EQT set. MaxPartRatio is the maximum aspect ratio of the set CU.
  • the determining unit 1102 is specifically configured to: according to the block information of the current image block, determine whether the current image block meets the conditions in the second condition set; when the current image block meets all the conditions in the second condition set, determine the HEQT
  • the division method is the available division method.
  • the second condition set includes the following conditions: (1) width ⁇ MaxEqtSize; (2) height ⁇ MaxEqtSize; (3)width ⁇ MinEqtSize*2; (4)height ⁇ MinEqtSize*4; (5)width*4 ⁇ MaxPartRatio *height; (7) width*MaxPartRatio ⁇ height; where width is the width of the current image block, heigh is the height of the current image block, MaxEqtSize is the size of the largest EQT, MinEqtSize is the size of the smallest EQT, and MaxPartRatio is the set CU The maximum aspect ratio.
  • the determining unit 1102 is further configured to determine that the current image block is within the boundary of the current image block according to the block information of the current image block.
  • the determining unit 1102 is specifically configured to: according to the block information of the current image block, determine whether the current image block meets the third condition; when the current image block meets the third condition, determine that the current image block is in the current image block Within the boundary.
  • the third condition is: (x0+width) ⁇ PicWidth, and (y0+height) ⁇ PicHeight; where x0 is the abscissa of the pixel point of the upper left vertex of the current image block in the image coordinate system, and the y0 is the image coordinate
  • the ordinate of the pixel of the upper left vertex of the current image block in the system, the origin of the image coordinate system is the pixel of the upper left vertex of the image where the current image block is located, and the horizontal axis of the image coordinate system is the width direction of the image where the current image block is located
  • the vertical axis of the image coordinate system is the height direction of the image where the current image block is located; PicWidth is the width of the image where
  • the determining unit 1102 is further configured to: determine, according to the block information of the current image block, that the current image block exceeds the boundary of the image where the current image block is located; according to the block information, the size of the set maximum BT, and the size of the set maximum EQT, Determine whether the QT division method is an available division method.
  • the determining unit 1102 is specifically configured to: according to the block information of the current image block, determine whether the current image block meets the conditions in the third condition set; if the current image block meets at least one condition in the third condition set, determine QT division method is available division method.
  • the third condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; width is the width of the current image block, heigh is the height of the current image block, MaxBTSize is the size of the set maximum BT, MaxEqtSize is the size of the set maximum EQT, and max(
  • the determining unit 1102 is specifically configured to determine whether the current image block satisfies the condition in the fourth condition set according to the block information of the previous image block; if the current image block satisfies at least one condition in the fourth condition set, determine QT division method is available division method.
  • the fourth condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; (11) the current image block does not exceed the right boundary of the image where the image block is located, And does not exceed the lower boundary of the image where the image block is located; width is the width of the current image block, heigh is the height of
  • MaxEqtSize is 2 M , where the value of M is 3, 4, 5, or 6.
  • the determining unit 1102 is specifically configured to: when there is one available division manner, determine the available division manner as the division manner of the current image block.
  • the determining unit 1102 is specifically configured to: when there are multiple available division modes, analyze the code stream including the current image block according to the determined available division mode, and determine the division mode of the current image block according to the analysis result.
  • the determining unit 1102 is specifically configured to: when there are multiple available partitioning methods, determine the rate-distortion cost of each available partitioning method separately, and determine the available partitioning method with the smallest rate-distortion cost among the available partitioning methods as the current image How the blocks are divided.
  • the video encoding device 1100 is used to implement the image division method as shown in FIG. 9, where:
  • the obtaining unit 1101 is configured to obtain block information of the current image block.
  • the determining unit 1102 is configured to determine available partitioning methods from the candidate partitioning method set according to the block information acquired by the acquiring unit 1101; wherein the candidate partitioning method set includes the quadtree QT partitioning method, when the current image block exceeds the current image block At the boundary of the image, determine whether the QT division method is an available division method according to the block information, the set maximum BT size, and the set maximum EQT size; and, from the determined available division methods, determine the The division method of the current image block.
  • the dividing unit 1103 is configured to obtain one coding unit CU or multiple CUs from the current image block according to the dividing mode of the current image block.
  • the determining unit 1102 is specifically configured to: according to the block information of the current image block, determine whether the current image block meets the conditions in the first condition set; if the current image block meets at least one condition in the first condition set, determine QT division method is available division method.
  • the first condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; width is the width of the current image block, heigh is the height of the current image block, MaxBTSize is the size of the set maximum BT, MaxEqtSize is the size of the set maximum EQT, and max(MaxBTS
  • the determining unit 1102 is specifically configured to determine whether the current image block satisfies the conditions in the second condition set according to the block information of the previous image block; if the current image block satisfies at least one condition in the second condition set, determine QT division method is available division method.
  • the second condition set includes one or more of the following conditions: (1) width>MaxBTSize, and width>MaxEqtSize; (2) height>MaxBTSize, and height>MaxEqtSize; (3) width>MaxBTSize, width>MaxEqtSize , Height>MaxBTSize, and height>MaxEqtSize; (4) width>max (MaxBTSize, MaxEqtSize); (5) height>max (MaxBTSize, MaxEqtSize); (6) width>max (MaxBTSize, MaxEqtSize), and height>max (MaxBTSize, MaxEqtSize); (7) width>MaxBTSize; (8) height>MaxBTSize; (9) width>MaxEqtSize; (10) height>MaxEqtSize; (11) the current image block does not exceed the right boundary of the image where the image block is located, And does not exceed the lower boundary of the image where the image block is located; width is the width of the current image block, heigh is the height of
  • MaxEqtSize is 2 M , where the value of M is 3, 4, 5, or 6.
  • the determining unit 1102 is specifically configured to: when there is one available division manner, determine the available division manner as the division manner of the current image block.
  • the determining unit 1102 is specifically configured to: when there are multiple available division modes, analyze the code stream including the current image block according to the determined available division mode, and determine the division mode of the current image block according to the analysis result.
  • the determining unit 1102 is specifically configured to: when there are multiple available partitioning methods, determine the rate-distortion cost of each available partitioning method separately, and determine the available partitioning method with the smallest rate-distortion cost among the available partitioning methods as the current image How the blocks are divided.
  • each unit in the image division device provided by the embodiment of the application is a functional body that implements the various execution steps included in the image division method of this application, that is, it has the ability to realize the complete realization of the image division method provided in this application. Please refer to the introduction to the image division method in this article for details of the steps of each step and the functional main body of the expansion and deformation of these steps. For the sake of brevity, I will not repeat them here.
  • the division of units in the embodiments of the present application is illustrative, and is only a logical function division, and other division methods may be used in actual implementation.
  • the functional modules in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit. If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium.
  • the technical solution of this application essentially or the part that contributes to the existing technology or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , Including a number of instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) execute all or part of the steps of the method described in each embodiment of the present application.
  • the aforementioned storage media include: portable hard disk, ROM, RAM, magnetic disk or optical disk and other media that can store program codes.
  • an embodiment of the present application also provides a video encoding device 1200.
  • the video encoding device 1200 includes a memory 1201 and a processor 1202, and the memory 1201 and the processor 1202 are connected to each other.
  • the processor 1202 is configured to call the program code stored in the memory 1201 to execute any one of the possible implementation manners of the first image division method provided in this application.
  • the processor 1202 is configured to call the program code stored in the memory 1201 to execute any one of the possible implementation manners of the second image division method provided in this application.
  • the computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium, such as a data storage medium, or a communication medium that includes any medium that facilitates the transfer of a computer program from one place to another (for example, according to a communication protocol) .
  • computer-readable media may generally correspond to (1) non-transitory tangible computer-readable storage media, or (2) communication media, such as signals or carrier waves.
  • Data storage media can be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and/or data structures for implementing the techniques described in this application.
  • the computer program product may include a computer-readable medium.
  • such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory, or structures that can be used to store instructions or data Any other media that can be accessed by the computer in the form of desired program code. And, any connection is properly termed a computer-readable medium.
  • any connection is properly termed a computer-readable medium.
  • coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave to transmit instructions from a website, server, or other remote source
  • coaxial cable Wire, fiber optic cable, twisted pair, DSL or wireless technologies such as infrared, radio and microwave are included in the definition of media.
  • the computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other temporary media, but are actually directed to non-transitory tangible storage media.
  • magnetic disks and optical discs include compact discs (CD), laser discs, optical discs, digital versatile discs (DVD), and Blu-ray discs. Disks usually reproduce data magnetically, while discs use lasers to reproduce data optically. data. Combinations of the above should also be included in the scope of computer-readable media.
  • DSP digital signal processors
  • ASIC application-specific integrated circuits
  • FPGA field programmable logic arrays
  • processor may refer to any of the foregoing structure or any other structure suitable for implementing the techniques described herein.
  • DSP digital signal processors
  • ASIC application-specific integrated circuits
  • FPGA field programmable logic arrays
  • the term "processor” as used herein may refer to any of the foregoing structure or any other structure suitable for implementing the techniques described herein.
  • the functions described by the various illustrative logical blocks, modules, and steps described herein may be provided in dedicated hardware and/or software modules configured for encoding and decoding, or combined Into the combined codec.
  • the technology may be fully implemented in one or more circuits or logic elements.
  • the technology of this application can be implemented in a variety of devices or devices, including wireless handsets, integrated circuits (ICs), or a set of ICs (for example, chipsets).
  • ICs integrated circuits
  • a set of ICs for example, chipsets.
  • Various components, modules, or units are described in this application to emphasize the functional aspects of the device for performing the disclosed technology, but they do not necessarily need to be implemented by different hardware units.
  • various units can be combined with appropriate software and/or firmware in the codec hardware unit, or by interoperating hardware units (including one or more processors as described above). provide.

Abstract

本申请提供了一种图像划分方法、装置及设备，以避免对边界图像块进行划分时出现必须划分单没有可用的划分方式的图像块，影响编码性能。该方法包括：获取当前图像块的块信息；根据获取到的块信息，从候选划分方式集合中确定可用划分方式；从确定出的可用划分方式中，确定当前图像块的划分方式；根据当前图像块的划分方式，从当前图像块得到一个CU或多个CU，其中，每个CU的宽高比满足设定的CU的最大宽高比。

Description

一种图像划分方法、装置及设备
相关申请的交叉引用
本申请要求在2019年05月04日提交中国专利局、申请号为201910377382.2、申请名称为“一种图像划分方法、装置及设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及视频编码领域，尤其涉及一种图像划分方法、装置及设备。
背景技术
视频编码(video coding)(包括视频编码(video decoding)和视频编码(video encoding))广泛用于数字视频应用，例如广播数字电视、互联网和移动网络上的视频传播、视频聊天和视频会议等实时会话应用、DVD和蓝光光盘、视频内容采集和编辑系统以及可携式摄像机的安全应用。
对视频中的一帧图像进行编码时，首先需要将图像划分为等大小的图像块，称为最大编码单元(largest coding unit，LCU)，再对一个LCU进行递归的划分操作，可以得到一个或多个编码单元(coding unit，CU)。现有编码标准在四叉树(quad-tree，QT)划分方式的基础上，增加了二叉树(binary tree，BT)划分方式(包括水平二分树(horizontal binary tree，HBT)和竖直二分树(vertical binary tree，VBT))和扩展四叉树(extended quad tree，EQT)划分方式(包括水平扩展四分树(horizontal extended quad tree，HEQT)和竖直扩展四分树(vertical extended quad tree，VEQT))。
在现有的最大BT的尺寸(MaxBTSize)和/或最大EQT的尺寸(MaxEqtSize)的配置下，按照现有技术中编码树定义语法，对于某些编码单元(coding unit,CU)的最大宽高比(MaxPartRatio)，对边界LCU进行划分时，可能会出现必须划分单没有可用的划分方式的图像块。例如，当编码单元的最大宽高比(MaxPartRatio)为4时，对边界LCU进行划分，可能会出现宽高比为1:8或者8:1的图像块，例如8×64的图像块或者64×8的图像块，为了满足编码单元的最大宽高比为4的约束，宽高比为1:8或者8:1的图像块必须要划分，由于划分过程中会受到最大划分深度的影响，当该图像块只能划分一次时，会存在以下情况：1)该图像块继续使用EQT划分，但是使用EQT划分后还会产生宽高比为1:8或者8:1的图像块或者CU，此时EQT划分方式不可用；2)当MaxBTSize配置为小于64时，8×64或者64×8的图像块不能使用BT划分。也就是说，8x64或者64x8的图像块不能使用EQT划分，BT划分，QT划分，又不能不分，进而影响编码性能。
发明内容
本申请提供了一种图像划分方法、装置及设备，以避免对边界图像块进行划分时出现必须划分单没有可用的划分方式的图像块，影响编码性能。
第一方面，本申请提供了一种图像划分方法，应用于视频编码(包括编码和解码) 过程，该方法包括：获取当前图像块的块信息；根据获取到的块信息，从候选划分方式集合中确定可用划分方式；从确定出的可用划分方式中，确定当前图像块的划分方式；根据当前图像块的划分方式，从当前图像块得到一个CU或多个CU，其中，每个CU的宽高比满足设定的CU的最大宽高比。
通过上述方法，在视频编码过程中，对当前图像块进行划分时，能够将图像块划分为一个或多个满足设定的CU最大宽高比的CU，能够解决现有技术中图像划分过程中，由于设定的CU最大宽高比的限定，出现必须划分但无法划分的图像块的问题，进而可以提高编码性能。
一个可能的实施方式中，当前图像块的块信息可以包括当前图像块的尺寸信息，例如当前图像块的宽度、当前图像块的高度或者基于当前图像块的宽度和高度得到的面积。当前图像块的块信息还可以包括当前图像块中像素点的坐标，例如当前图像块中像素点在图像坐标系中的坐标，其中，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向(x轴)，图像坐标系的纵轴为当前图像块所在的图像的高度方向(y轴)。进一步地，当前图像的块信息还可以包括当前图像块对应的其他图像相关信息，例如，当前图像块是否超出当前图像的边界，对于视频解码端设备这些块信息能够从当前图像的码流中解析或者推导得到。
进一步地，可以通过以下方法判断当前图像块是否超出当前图像块所在图像的边界：根据图像块的块信息，获得当前图像块中的一个像素点的坐标(x，y)；判断像素点的坐标(x，y)是否满足预设条件，若像素点的坐标(x，y)满足第一预设条件，则表明当前图像块出当前图像块所在图像的右边界，若像素点的坐标(x，y)满足第二预设条件，则表明图像块超出当前图像块所在图像的下边界，若像素点的坐标(x，y)满足第三预设条件，则表明当前图像块超出当前图像块所在图像的右边界且超出当前图像的下边界(简称右下边界)，若像素点的坐标(x，y)满足第四预设条件，则表明当前图像块超出当前图像块所在图像的边界，也即，图片可能超出了图像的下边界，或者超出图像的右边界，或者超出了图像的右下边界。另外，若像素点的坐标(x，y)满足第四预设条件，但不满足第一预设条件和第二预设条件，则表明当前图像块超出当前图像块所在图像的右下边界。
其中，所选择的像素点用于表征当前图像块，可以选取当前图像块中特定的像素点来表示当前图像块，如选取当前图像块的顶点的像素点，如左上顶点的像素点、右上顶点的像素点、左下顶点的像素点或者右下顶点的像素点，当然，还可以选取当前图像块的中心位置的像素点，还可以选取当前图像块中除上述像素点外的任意一个像素点。上述的第一预设条件、第二预设条件、第三预设条件以及第四预设条件则可根据所选择的像素点的位置、当前图像块所在图像的尺寸确定。
一个可能的实施方式中，设定的CU的最大宽高比可以为4或者8。
一个可能的实施方式中，候选划分方式集合包括但不限于不划分方式、水平二叉树HBT划分方式，垂直二叉树VBT划分方式，水平扩展四叉树HEQT划分方式，垂直扩展四叉树VEQT划分方式以及四叉树QT划分方式中的一种或多种。
一个可能的实施方式中，根据所述块信息，从候选划分方式集合中确定可用划分方式具体包括以下步骤：根据块信息，判断当前图像块是否满足第一条件，当当前图像块满足 第一条件时，确定VBT划分方式为可用划分方式。其中，第一条件为width>height*MaxPartRatio，width为当前图像块的宽度，height为当前图像块的高度，MaxPartRatio为设定的CU的最大宽高比。
通过上述方案，相较于现有技术，本申请放宽了使用VBT划分方式的条件，在当前图像块的宽度于高度的比值大于设定的CU的最大宽高比时，可以采用进VBT划分方式，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
一个可能的实施方式中，根据所述块信息，从候选划分方式集合中确定可用划分方式具体包括以下步骤：根据所述块信息，从候选划分方式集合中确定可用划分方式具体包括以下步骤：根据块信息，判断当前图像块是否满足第二条件；当当前图像块满足所述第二条件时，确定HBT划分方式为可用划分方式。其中，第二条件为height>width*MaxPartRatio，width为当前图像块的宽度，height为当前图像块的高度，MaxPartRatio为设定的CU的最大宽高比。
通过上述方案，相较于现有技术，本申请放宽了使用HBT划分方式的条件，在当前图像块的高度与宽度的比值大于设定的CU的最大宽高比时，可以采用进HBT划分方式，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
一个可能的实施方式中，根据所述块信息，从候选划分方式集合中确定可用划分方式具体包括以下步骤：根据块信息，判断当前图像块是否满足第一条件集合中的条件；当当前图像块满足第一条件集合中的所有条件时，确定VEQT划分方式为可用划分方式。其中，第一条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)height≥MinEqtSize*2；(4)width≥MinEqtSize*4；(5)height*4≤MaxPartRatio*width；(6)height*MaxPartRatio≥width；其中，width为当前图像块的宽度，height为当前图像块的高度，MaxEqtSize为设定的最大EQT的尺寸，MinEqtSize为设定的最小EQT的尺寸，MaxPartRatio为设定的CU的最大宽高比。
通过上述方案，相较于现有技术，本申请紧缩了使用VEQT划分方式的条件，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
一个可能的实施方式中，根据所述块信息，从候选划分方式集合中确定可用划分方式具体包括以下步骤：根据块信息，判断当前图像块是否满足第二条件集合中的条件；当当前图像块满足所述第二条件集合中的所有条件时，确定HEQT划分方式为可用划分方式。其中，第二条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)width≥MinEqtSize*2；(4)height≥MinEqtSize*4；(5)width*4≤MaxPartRatio*height；(7)width*MaxPartRatio≥height；其中，width为当前图像块的宽度，heigh为当前图像块的高度，MaxEqtSize为最大EQT的尺寸，MinEqtSize为最小EQT的尺寸，MaxPartRatio为CU的最大宽高比。
通过上述方案，相较于现有技术，本申请紧缩了使用HEQT划分方式的条件，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
一个可能的实施方式中，该方法还包括根据当前图像块的块信息，确定当前图像块在 当前图像块所在的图像的边界内。
一个可能的实施方式中，可以通过以下步骤确定当前图像块在当前图像块的边界内：根据当前图像块的块信息，判断当前图像块是否满足第三条件；当当前图像块满足所述第三条件时，确定当前图像块在当前图像块的边界内。其中，第三条件为：(x0+width)≤PicWidth，且(y0+height)≤PicHeight，x0为图像坐标系中当前图像块左上顶点的像素点的横坐标，y0为图像坐标系中当前图像块左上顶点的像素点的纵坐标，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向，图像坐标系的纵轴为当前图像块所在的图像的高度方向，PicWidth为当前图像块所在的图像的宽度，PicHeight为当前图像块所在的图像的高度。
一个可能的实施方式中，该方法还包括，根据当前图像块的块信息确定当前图像块超出当前图像块所在图像的边界，并根据当前图像块的块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断QT划分方式是否为可用划分方式。
一个可能的实施方式中，可以通过以下方法确定当前图像块超出当前图像块所在图像的边界：根据当前图像块的块信息，判断当前图像块是否满足第四条件；当当前图像块满足所述第四条件时，确定当前图像块超出当前图像块的边界。其中，第四条件为：(x0+width)＞PicWidth，且(y0+height)＞PicHeight，x0为图像坐标系中当前图像块左上顶点的像素点的横坐标，y0为图像坐标系中当前图像块左上顶点的像素点的纵坐标，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向，图像坐标系的纵轴为当前图像块所在的图像的高度方向，PicWidth为当前图像块所在的图像的宽度，PicHeight为当前图像块所在的图像的高度。
一个可能的实施方式中，当当前图像块超出当前图像块所在图像的边界时，可以通过以下方式判断QT划分方式是否为可用划分方式：根据图像块的块信息，判断当前图像块是否满足第三条件集合中的条件；若当前图像块满足第三条件集合中的至少一个条件，则QT划分方式为可用划分方式。
其中，第三条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
一个可能的实施方式中，当当前图像块超出当前图像块所在图像的边界时，可以通过以下方式判断QT划分方式是否为可用划分方式：根据图像块的块信息，判断当前图像块是否满足第四条件集合中的条件；若当前图像块满足第四条件集合中的至少一个条件，则QT划分方式为可用划分方式。
其中，所述第四条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width ＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)当前图像块未超出图像块所在图像的右边界，且未超出图像块所在图像的下边界；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
通过上述方案，在图像划分过程中，当当前图像块超出图像块所在图像的边界时采用QT划分方式，避免对边界图像块划分得到N×64或64×N(N<64)的图像块，进而避免当MaxBTSize和MaxEqtSize设置为小于64时，N×64或64×N(N<64)的图像块无法继续划分的问题。
一个可能的实施方式中，MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
一个可能的实施方式中，对于解码端设备，可以通过以下方式从确定出的可用划分方式中，确定当前图像块的划分方式：当可用划分方式为一种时，将可用划分方式确定为当前图像块的划分方式；当可用划分方式为多种时，根据确定出的可用划分方式，解析包括当前图像块的码流，并根据解析结果确定当前图像块的划分方式。
一个可能的实施方式中，对于编码端设备，可以通过以下方式从确定出的可用划分方式中，确定当前图像块的划分方式：当可用划分方式为一种时，将可用划分方式确定为当前图像块的划分方式；当可用划分方式为多种时，分别确定每个可用划分方式的率失真代价，将可用划分方式中率失真代价最小的可用划分方式，确定为当前图像块的划分方式。
第二方面，本申请还提供了另一种图像划分方法，应用于视频编码过程，该方法包括：获取当前图像块的块信息；根据获取到的块信息，从候选划分方式集合中确定可用划分方式，其中，当当前图像块超出当前图像块所在图像的边界时，根据当前图像块的块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断候选划分方式集合中QT划分方式是否为可用划分方式；从确定出的可用划分方式中，确定当前图像块的划分方式；根据当前图像块的划分方式，从当前图像块得到一个CU或多个CU。
通过上述方案，在视频编码过程中，对当前图像块进行划分时，当当前图像块超出图像块所在图像的边界时尽量采用QT划分方式，避免对边界图像块划分得到N×64或64×N(N<64)的图像块，进而避免当MaxBTSize和MaxEqtSize设置为小于64时，N×64或64×N(N<64)的图像块无法继续划分的问题，进而可以提高编码性能。
一个可能的实施方式中，当前图像块的块信息可以包括当前图像块的尺寸信息，例如当前图像块的宽度、当前图像块的高度或者基于当前图像块的宽度和高度得到的面积。当前图像块的块信息还可以包括当前图像块中像素点的坐标，例如当前图像块中像素点在图像坐标系中的坐标，其中，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向(x轴)，图像坐标系的纵轴为当前图像块所在的图像的高度方向(y轴)。进一步地，当前图像的块信息还可以包括当前图像块对应的其他图像相关信息，例如，当前图像块是否超出当前图像的边界，对于视频解码端设备这些块信息能够从当前图像的码流中解析或者推导得到。
一个可能的实施方式中，候选划分方式集合还可以包括但不限于不划分方式、水平二 叉树HBT划分方式，垂直二叉树VBT划分方式，水平扩展四叉树HEQT划分方式，以及垂直扩展四叉树VEQT划分方式中的一种或多种。
一个可能的实施方式中，可以通过以下方法确定当前图像块超出当前图像块所在图像的边界：根据当前图像块的块信息，判断当前图像块是否满足第四条件；当当前图像块满足所述第四条件时，确定当前图像块超出当前图像块的边界。其中，第四条件为：(x0+width)＞PicWidth，且(y0+height)＞PicHeight，x0为图像坐标系中当前图像块左上顶点的像素点的横坐标，y0为图像坐标系中当前图像块左上顶点的像素点的纵坐标，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向，图像坐标系的纵轴为当前图像块所在的图像的高度方向，PicWidth为当前图像块所在的图像的宽度，PicHeight为当前图像块所在的图像的高度。
一个可能的实施方式中，当当前图像块超出当前图像块所在图像的边界时，可以通过以下方式判断QT划分方式是否为可用划分方式：根据图像块的块信息，判断当前图像块是否满足第一条件集合中的条件；若当前图像块满足第一条件集合中的至少一个条件，则QT划分方式为可用划分方式。
其中，第一条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
一个可能的实施方式中，当当前图像块超出当前图像块所在图像的边界时，可以通过以下方式判断QT划分方式是否为可用划分方式：根据图像块的块信息，判断当前图像块是否满足第二条件集合中的条件；若当前图像块满足第二条件集合中的至少一个条件，则QT划分方式为可用划分方式。
其中，第二条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)当前图像块未超出图像块所在图像的右边界，且未超出图像块所在图像的下边界；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
通过上述方案，在图像划分过程中，当当前图像块超出图像块所在图像的边界时采用QT划分方式，避免对边界图像块划分得到N×64或64×N(N<64)的图像块，进而避免当MaxBTSize和MaxEqtSize设置为小于64时，N×64或64×N(N<64)的图像块无法继续划 分的问题。
一个可能的实施方式中，MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
一个可能的实施方式中，对于解码端设备，可以通过以下方式从确定出的可用划分方式中，确定当前图像块的划分方式：当可用划分方式为一种时，将可用划分方式确定为当前图像块的划分方式；当可用划分方式为多种时，根据确定出的可用划分方式，解析包括当前图像块的码流，并根据解析结果确定当前图像块的划分方式。
一个可能的实施方式中，对于编码端设备，可以通过以下方式从确定出的可用划分方式中，确定当前图像块的划分方式：当可用划分方式为一种时，将可用划分方式确定为当前图像块的划分方式；当可用划分方式为多种时，分别确定每个可用划分方式的率失真代价，将可用划分方式中率失真代价最小的可用划分方式，确定为当前图像块的划分方式。
第三方面，本申请还提供了一种图像划分装置，该图像划分装置具有实现上述第一方面所述的任意一种可能的实施方式中所述的图像划分方法的功能。该图像划分装置包括获取单元、确定单元和划分单元，这些单元可以执行上述第一方面所述的方法示例中的相应功能，具体参见方法示例中的详细描述，此处不做赘述。
第四方面，本申请还提供了一种视频编码设备，该视频编码设备具有实现上述第一方面的任意一种可能的实施方式中所述的图像划分方法的功能。该视频编码设备的结构中包括存储器以及处理器，该处理器被配置为支持视频编码设备执行上述第一方面的任意一种可能的实施方式中所述的方法中相应的功能。存储器与处理器耦合，其保存视频编码设备必要的程序指令和数据。
第五方面，本申请还提供了另一种图像划分装置，该图像划分装置具有实现上述第二方面所述的任意一种可能的实施方式中所述的图像划分方法的功能。该图像划分装置包括获取单元、确定单元和划分单元，这些单元可以执行上述第二方面所述的方法示例中的相应功能，具体参见方法示例中的详细描述，此处不做赘述。
第六方面，本申请还提供了另一种视频编码设备，该视频编码设备具有实现上述第二方面的任意一种可能的实施方式中所述的图像划分方法的功能。该视频编码设备的结构中包括存储器以及处理器，该处理器被配置为支持视频编码设备执行上述第二方面的任意一种可能的实施方式中所述的方法中相应的功能。存储器与处理器耦合，其保存视频编码设备必要的程序指令和数据。
第七方面，本申请还提供一种计算机存储介质，该存储介质中存储有软件程序，该软件程序在被一个或多个处理器读取并执行时可实现任一方面的任意一种实施方式提供的方法。
第八方面，本申请还提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述任一方面中的任一种方法。
附图说明
图1A为本申请实施例提供的视频编码及解码系统的结构示意图；
图1B为本申请实施例提供的视频译码系统的结构示意图；
图2为本申请实施例提供的编码器的结构示意图；
图3为本申请实施例提供的解码器的结构示意图；
图4为本申请实施例提供的一种视频译码设备的结构示意图；
图5为本申请实施例提供的另一种视频译码设备的结构示意图；
图6为本申请实施例提供的二叉树，四叉树以及扩展四叉树的划分方式示意图；
图7为本申请实施例提供的QT-MTT划分示意图；
图8为本申请实施例提供的一种图像划分方法的流程示意图；
图9为本申请实施例提供的图像坐标系的示意图；
图10为本申请实施例提供的另一种图像划分方法的流程示意图；
图11为本申请实施例提供的一种图像划分装置的结构示意图；
图12为本申请实施例提供的一种视频编码设备的结构示意图。
具体实施方式
视频编码过程中，需要将每帧图像先将图像划分为等大小的LCU，并将LCU递归划分为一个或多个CU。在数字音视频编解码(audio video coding standard workgroup of China，AVS)技术标准中，LCU的尺寸为128x128或64x64，使用了QT级联BT/EQT的划分方式，即第一级编码树(coding tree)上的节点只能使用QT划分成子节点，第一级编码树的叶节点为第二级编码树的根节点；第二级编码树上的节点可使用BT或EQT划分方式中的一种划分为子节点；第二级编码树的叶节点为编码单元。需要注意的是，当叶节点为BT或EQT划分方式时，其叶节点只能使用BT或EQT划分方式，而不能使用QT的方式。
现有的AVS3的编码树定义的部分语法如表1所示，按照表1所示的编码树定义语法，对于某些编码单元(coding unit,CU)的最大宽高比(MaxPartRatio)，对边界LCU进行划分时，可能会出现必须划分单没有可用的划分方式的图像块。例如，当编码单元的最大宽高比(MaxPartRatio)为4时，对边界LCU进行划分，可能会出现宽高比为1:8或者8:1的图像块，例如8x64的图像块或者64x8的图像块，为了满足编码单元的最大宽高比为4的约束，宽高比为1:8或者8:1的图像块必须要划分，由于划分过程中会受到最大划分深度的影响，当该图像块只能划分一次时，会存在以下情况：1)该图像块继续使用EQT划分，但是使用EQT划分后还会产生宽高比为1:8或者8:1的图像块或者CU，此时EQT划分方式不可用；2)当MaxBTSize配置为小于64时，8x64或者64x8的图像块不能使用BT划分。也就是说，8x64或者64x8的图像块不能使用EQT划分，BT划分，QT划分，又不能不分，进而影响编码性能。
表1 编码树定义语法
Figure PCTCN2020087289-appb-000001
Figure PCTCN2020087289-appb-000002
Figure PCTCN2020087289-appb-000003
为了解决现有视频编码技术中存在的上述问题，本申请提供了一种图像划分方法、装置及设备。其中，本申请实施例所述的方法和装置基于同一构思，由于方法和装置解决问题的原理相似，因此装置与方法的实施可以相互参见，重复之处不再赘述。
下面结合本申请实施例中的附图对本申请实施例进行描述。以下描述中，参考形成本公开一部分并以说明之方式示出本申请实施例的具体方面或可使用本申请实施例的具体方面的附图。应理解，本申请实施例可在其它方面中使用，并可包括附图中未描绘的结构或逻辑变化。因此，以下详细描述不应以限制性的意义来理解，且本申请的范围由所附权利要求书界定。例如，应理解，结合所描述方法的揭示内容可以同样适用于执行所述方法的对应设备或系统，且反之亦然。例如，如果描述一个或多个具体方法步骤，则对应的设备可以包含如功能单元等一个或多个单元，来执行所描述的一个或多个方法步骤(例如， 一个单元执行一个或多个步骤，或多个单元，其中每个都执行多个步骤中的一个或多个)，即使附图中未明确描述或说明这种一个或多个单元。另一方面，例如，如果基于如功能单元等一个或多个单元描述具体装置，则对应的方法可以包含一个步骤来执行一个或多个单元的功能性(例如，一个步骤执行一个或多个单元的功能性，或多个步骤，其中每个执行多个单元中一个或多个单元的功能性)，即使附图中未明确描述或说明这种一个或多个步骤。进一步，应理解的是，除非另外明确提出，本文中所描述的各示例性实施例和/或方面的特征可以相互组合。
本申请实施例所涉及的技术方案不仅可以应用于现有的视频编码标准中(如H.264、高性能视频编码(High Efficiency Video Coding，HEVC)等标准)，还可以应用于未来的视频编码标准中(如H.266标准)，或者可以AVS技术标准，如AVS3中。本申请的实施方式部分使用的术语仅用于对本申请的具体实施例进行解释，而非旨在限定本申请。下面先对本申请实施例可能涉及的一些概念进行简单介绍。
视频编码通常是指处理形成视频或视频序列的图片序列。在视频编码领域，术语“图片(picture)”、“帧(frame)”或“图像(image)”可以用作同义词。本文中使用的视频编码表示视频编码或视频解码。视频编码在源侧执行，通常包括处理(例如，通过压缩)原始视频图片以减少表示该视频图片所需的数据量，从而更高效地存储和/或传输。视频解码在目的地侧执行，通常包括相对于编码器作逆处理，以重构视频图片。实施例涉及的视频图片“编码”应理解为涉及视频序列的“编码”或“解码”。编码部分和解码部分的组合也称为编解码(编码和解码)。
视频序列包括一系列图像(picture)，图像被进一步划分为切片(slice)，切片再被划分为块(block)。视频编码以块为单位进行编码处理，在一些新的视频编码标准中，块的概念被进一步扩展。比如，在H.264标准中有宏块(macroblock，MB)，宏块可进一步划分成多个可用于预测编码的预测块(partition)。在HEVC标准中，采用编码单元，预测单元(prediction unit，PU)和变换单元(transform unit，TU)等基本概念，从功能上划分了多种块单元，并采用全新的基于树结构进行描述。比如视频编码标准把一帧图像分割成互不重叠的编码树单元(coding tree unit，CTU)，再把一个CTU划分为若干个子节点，这些子节点可以按照四叉树(quad tree，QT)进行划分为更小的子节点，而更小的子节点还可以继续划分，从而形成一种四叉树结构。如果节点不再划分，则叫做CU。CU是对编码图像进行划分和编码的基本单元。对于PU和TU也有类似的树结构，PU可以对应预测块，是预测编码的基本单元。对CU按照划分模式进一步划分成多个PU。TU可以对应变换块，是对预测残差进行变换的基本单元。然而，无论CU，PU还是TU，本质上都属于块(或称图像块)的概念。
例如在HEVC中，通过使用表示为编码树的四叉树结构将CTU拆分为多个CU。在CU层级处作出是否使用图片间(时间)或图片内(空间)预测对图片区域进行编码的决策。每个CU可以根据PU拆分类型进一步拆分为一个、两个或四个PU。一个PU内应用相同的预测过程，并在PU基础上将相关信息传输到解码器。在通过基于PU拆分类型应用预测过程获取残差块之后，可以根据类似于用于CU的编码树的其它四叉树结构将CU分割TU。在视频压缩技术最新的发展中，使用四叉树和二叉树(quad-tree and binary tree，QTBT)分割帧来分割编码块。在QTBT块结构中，CU可以为正方形或矩形形状。
本文中，为了便于描述和理解，可将当前编码图像中待编码的图像块称为当前块，例 如在编码中，指当前正在编码的块；在解码中，指当前正在解码的块。将参考图像中用于对当前块进行预测的已解码的图像块称为参考块，即参考块是为当前块提供参考信号的块，其中，参考信号表示图像块内的像素值。可将参考图像中为当前块提供预测信号的块为预测块，其中，预测信号表示预测块内的像素值或者采样值或者采样信号。例如，在遍历多个参考块以后，找到了最佳参考块，此最佳参考块将为当前块提供预测，此块称为预测块。
无损视频编码情况下，可以重构原始视频图片，即经重构视频图片具有与原始视频图片相同的质量(假设存储或传输期间没有传输损耗或其它数据丢失)。在有损视频编码情况下，通过例如量化执行进一步压缩，来减少表示视频图片所需的数据量，而解码器侧无法完全重构视频图片，即经重构视频图片的质量相比原始视频图片的质量较低或较差。
H.261的几个视频编码标准属于“有损混合型视频编解码”(即，将样本域中的空间和时间预测与变换域中用于应用量化的2D变换编码结合)。视频序列的每个图片通常分割成不重叠的块集合，通常在块层级上进行编码。换句话说，编码器侧通常在块(视频块)层级处理亦即编码视频，例如，通过空间(图片内)预测和时间(图片间)预测来产生预测块，从当前块(当前处理或待处理的块)减去预测块以获取残差块，在变换域变换残差块并量化残差块，以减少待传输(压缩)的数据量，而解码器侧将相对于编码器的逆处理部分应用于经编码或经压缩块，以重构用于表示的当前块。另外，编码器复制解码器处理循环，使得编码器和解码器生成相同的预测(例如帧内预测和帧间预测)和/或重构，用于处理亦即编码后续块。
参见图1A，图1A示例性地给出了本申请实施例所应用的视频编码及解码系统10的示意性结构框图，视频编码及解码系统10可包括源设备12和目的地设备14，其中，源设备12产生经编码的视频数据，因此，源设备12可被称为视频编码装置；目的地设备14可对由源设备12所产生的经编码的视频数据进行解码，因此，目的地设备14可被称为视频解码装置。源设备12、目的地设备14或两个的各种实施方案可包含一或多个处理器以及耦合到所述一或多个处理器的存储器。所述存储器可包含但不限于随机存储器(random access memory，RAM)、只读存储器(read-only memory，ROM)、带电可擦可编程只读存储器(electrically erasable programmable read only memory，EEPROM)、快闪存储器或可用于以可由计算机存取的指令或数据结构的形式存储所要的程序代码的任何其它媒体，如本文所描述。源设备12和目的地设备14可以包括各种装置，包含桌上型计算机、移动计算装置、笔记型(例如，膝上型)计算机、平板计算机、机顶盒、例如所谓的“智能”电话等电话手持机、电视机、相机、显示装置、数字媒体播放器、视频游戏控制台、车载计算机、无线通信设备或其类似者。
虽然图1A将源设备12和目的地设备14绘示为单独的设备，但设备实施例也可以同时包括源设备12和目的地设备14或同时包括两者的功能性，即源设备12或对应的功能性以及目的地设备14或对应的功能性。在此类实施例中，可以使用相同硬件和/或软件，或使用单独的硬件和/或软件，或其任何组合来实施源设备12或对应的功能性以及目的地设备14或对应的功能性。
源设备12和目的地设备14之间可通过链路13进行通信连接，目的地设备14可经由链路13从源设备12接收经编码视频数据。链路13可包括能够将经编码视频数据从源设备12移动到目的地设备14的一或多个媒体或装置。在一个实例中，链路13可包括使得源设备12能够实时将经编码视频数据直接发射到目的地设备14的一或多个通信媒体。在 此实例中，源设备12可根据通信标准(例如无线通信协议)来调制经编码视频数据，且可将经调制的视频数据发射到目的地设备14。所述一或多个通信媒体可包含无线和/或有线通信媒体，例如射频(RF)频谱或一或多个物理传输线。所述一或多个通信媒体可形成基于分组的网络的一部分，基于分组的网络例如为局域网、广域网或全球网络(例如，因特网)。所述一或多个通信媒体可包含路由器、交换器、基站或促进从源设备12到目的地设备14的通信的其它设备。
源设备12包括编码器20，另外可选地，源设备12还可以包括图片源16、图片预处理器18、以及通信接口22。具体实现形态中，所述编码器20、图片源16、图片预处理器18、以及通信接口22可能是源设备12中的硬件部件，也可能是源设备12中的软件程序。分别描述如下：
图片源16，可以包括或可以为任何类别的图片捕获设备，用于例如捕获现实世界图片，和/或任何类别的图片或评论(对于屏幕内容编码，屏幕上的一些文字也认为是待编码的图片或图像的一部分)生成设备，例如，用于生成计算机动画图片的计算机图形处理器，或用于获取和/或提供现实世界图片、计算机动画图片(例如，屏幕内容、虚拟现实(virtual reality，VR)图片)的任何类别设备，和/或其任何组合(例如，实景(augmented reality，AR)图片)。图片源16可以为用于捕获图片的相机或者用于存储图片的存储器，图片源16还可以包括存储先前捕获或产生的图片和/或获取或接收图片的任何类别的(内部或外部)接口。当图片源16为相机时，图片源16可例如为本地的或集成在源设备中的集成相机；当图片源16为存储器时，图片源16可为本地的或例如集成在源设备中的集成存储器。当所述图片源16包括接口时，接口可例如为从外部视频源接收图片的外部接口，外部视频源例如为外部图片捕获设备，比如相机、外部存储器或外部图片生成设备，外部图片生成设备例如为外部计算机图形处理器、计算机或服务器。接口可以为根据任何专有或标准化接口协议的任何类别的接口，例如有线或无线接口、光接口。
其中，图片可以视为像素点(picture element)的二维阵列或矩阵。阵列中的像素点也可以称为采样点。阵列或图片在水平和垂直方向(或轴线)上的采样点数目定义图片的尺寸和/或分辨率。为了表示颜色，通常采用三个颜色分量，即图片可以表示为或包含三个采样阵列。例如在RBG格式或颜色空间中，图片包括对应的红色、绿色及蓝色采样阵列。但是，在视频编码中，每个像素通常以亮度/色度格式或颜色空间表示，例如对于YUV格式的图片，包括Y指示的亮度分量(有时也可以用L指示)以及U和V指示的两个色度分量。亮度(luma)分量Y表示亮度或灰度水平强度(例如，在灰度等级图片中两者相同)，而两个色度(chroma)分量U和V表示色度或颜色信息分量。相应地，YUV格式的图片包括亮度采样值(Y)的亮度采样阵列，和色度值(U和V)的两个色度采样阵列。RGB格式的图片可以转换或变换为YUV格式，反之亦然，该过程也称为色彩变换或转换。如果图片是黑白的，该图片可以只包括亮度采样阵列。本申请实施例中，由图片源16传输至图片处理器的图片也可称为原始图片数据17。
图片预处理器18，用于接收原始图片数据17并对原始图片数据17执行预处理，以获取经预处理的图片19或经预处理的图片数据19。例如，图片预处理器18执行的预处理可以包括整修、色彩格式转换(例如，从RGB格式转换为YUV格式)、调色或去噪。
编码器20(或称视频编码器20)，用于接收经预处理的图片数据19，采用相关预测模式(如本文各个实施例中的预测模式)对经预处理的图片数据19进行处理，从而提供经 编码图片数据21(下文将进一步基于图2或图4或图5描述编码器20的结构细节)。通信接口22，可用于接收经编码图片数据21，并可通过链路13将经编码图片数据21传输至目的地设备14或任何其它设备(如存储器)，以用于存储或直接重构，所述其它设备可为任何用于解码或存储的设备。通信接口22可例如用于将经编码图片数据21封装成合适的格式，例如数据包，以在链路13上传输。
目的地设备14包括解码器30，另外可选地，目的地设备14还可以包括通信接口28、图片后处理器32和显示设备34。分别描述如下：
通信接口28，可用于从源设备12或任何其它源接收经编码图片数据21，所述任何其它源例如为存储设备，存储设备例如为经编码图片数据存储设备。通信接口28可以用于藉由源设备12和目的地设备14之间的链路13或藉由任何类别的网络传输或接收经编码图片数据21，链路13例如为直接有线或无线连接，任何类别的网络例如为有线或无线网络或其任何组合，或任何类别的私网和公网，或其任何组合。通信接口28可以例如用于解封装通信接口22所传输的数据包以获取经编码图片数据21。
通信接口28和通信接口22都可以配置为单向通信接口或者双向通信接口，以及可以用于例如发送和接收消息来建立连接、确认和交换任何其它与通信链路和/或例如经编码图片数据传输的数据传输有关的信息。
解码器30(或称为解码器30)，用于接收经编码图片数据21并提供经解码图片数据31或经解码图片31(下文将进一步基于图3或图4或图5描述解码器30的结构细节)。在一些实施例中，解码器30可以用于执行后文所描述的各个实施例，以实现本申请所描述的视频解码方法在解码侧的应用。
图片后处理器32，用于对经解码图片数据31(也称为经重构图片数据)执行后处理，以获得经后处理图片数据33。图片后处理器32执行的后处理可以包括：色彩格式转换(例如，从YUV格式转换为RGB格式)、调色、整修或重采样，或任何其它处理，还可用于将经后处理图片数据33传输至显示设备34。
显示设备34，用于接收经后处理图片数据33以向例如用户或观看者显示图片。显示设备34可以为或可以包括任何类别的用于呈现经重构图片的显示器，例如，集成的或外部的显示器或监视器。例如，显示器可以包括液晶显示器(liquid crystal display，LCD)、有机发光二极管(organic light emitting diode，OLED)显示器、等离子显示器、投影仪、微LED显示器、硅基液晶(liquid crystal on silicon，LCoS)、数字光处理器(digital light processor，DLP)或任何类别的其它显示器。
虽然，图1A将源设备12和目的地设备14绘示为单独的设备，但设备实施例也可以同时包括源设备12和目的地设备14或同时包括两者的功能性，即源设备12或对应的功能性以及目的地设备14或对应的功能性。在此类实施例中，可以使用相同硬件和/或软件，或使用单独的硬件和/或软件，或其任何组合来实施源设备12或对应的功能性以及目的地设备14或对应的功能性。
本领域技术人员基于描述明显可知，不同单元的功能性或图1A所示的源设备12和/或目的地设备14的功能性的存在和(准确)划分可能根据实际设备和应用有所不同。源设备12和目的地设备14可以包括各种设备中的任一个，包含任何类别的手持或静止设备，例如，笔记本或膝上型计算机、移动电话、智能手机、平板或平板计算机、摄像机、台式计算机、机顶盒、电视机、相机、车载设备、显示设备、数字媒体播放器、视频游戏控制 台、视频流式传输设备(例如内容服务服务器或内容分发服务器)、广播接收器设备、广播发射器设备等，并可以不使用或使用任何类别的操作系统。
编码器20和解码器30都可以实施为各种合适电路中的任一个，例如，一个或多个微处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application-specific integrated circuit，ASIC)、现场可编程门阵列(field-programmable gate array，FPGA)、离散逻辑、硬件或其任何组合。如果部分地以软件实施所述技术，则设备可将软件的指令存储于合适的非暂时性计算机可读存储介质中，且可使用一或多个处理器以硬件执行指令从而执行本公开的技术。前述内容(包含硬件、软件、硬件与软件的组合等)中的任一者可视为一或多个处理器。
在一些情况下，图1A中所示视频编码及解码系统10仅为示例，本申请的技术可以适用于不必包含编码和解码设备之间的任何数据通信的视频编码设置(例如，视频编码或视频解码)。在其它实例中，数据可从本地存储器检索、在网络上流式传输等。视频编码设备可以对数据进行编码并且将数据存储到存储器，和/或视频解码设备可以从存储器检索数据并且对数据进行解码。在一些实例中，由并不彼此通信而是仅编码数据到存储器和/或从存储器检索数据且解码数据的设备执行编码和解码。
参见图1B，图1B是根据一示例性实施例的包含图2的编码器20和/或图3的解码器30的视频译码系统40的实例的说明图，视频译码系统40可以实现本申请实施例的各种技术的组合。在所说明的实施方式中，视频译码系统40可以包含成像设备41、编码器20、解码器30(和/或借由逻辑电路47实施的视频编/解码器)、天线42、一个或多个处理器43、一个或多个存储器44和/或显示设备45。
如图1B所示，成像设备41、天线42、逻辑电路47、编码器20、解码器30、处理器43、存储器44和/或显示设备45能够互相通信。如所论述，虽然用编码器20和解码器30绘示视频译码系统40，但在不同实例中，视频译码系统40可以只包含编码器20或只包含解码器30。
在一些实例中，天线42可以用于传输或接收视频数据的经编码比特流。另外，在一些实例中，显示设备45可以用于呈现视频数据。在一些实例中，逻辑电路47可以包含专用集成电路(application-specific integrated circuit，ASIC)逻辑、图形处理器、通用处理器等。视频译码系统40也可以包含可选的处理器43，该可选处理器43类似地可以包含ASIC逻辑、图形处理器、通用处理器等。在一些实例中，逻辑电路47可以通过硬件实施，如视频编码专用硬件等，处理器43可以通过通用软件、操作系统等实施。另外，存储器44可以是任何类型的存储器，例如易失性存储器(例如，静态随机存取存储器(static random access memory，SRAM)、动态随机存储器(dynamic random access memory，DRAM)等)或非易失性存储器(例如，闪存等)等。在非限制性实例中，存储器44可以由超速缓存内存实施。在一些实例中，逻辑电路47可以访问存储器44(例如用于实施图像缓冲器)。在其它实例中，逻辑电路47可以包含存储器(例如，缓存等)用于实施图像缓冲器等。
在一些实例中，通过逻辑电路实施的编码器20可以包含(例如，通过存储器44实施的)图像缓冲器和图形处理单元。图形处理单元可以通信耦合至图像缓冲器。图形处理单元可以包含通过逻辑电路47实施的编码器20，以实施参照图2和/或本文中所描述的任何其它编码器系统或子系统所论述的各种模块。逻辑电路可以用于执行本文所论述的各种操作。
在一些实例中，解码器30可以以类似方式通过逻辑电路47实施，以实施参照图3的解码器30和/或本文中所描述的任何其它解码器系统或子系统所论述的各种模块。在一些实例中，逻辑电路实施的解码器30可以包含(通过处理单元2820或存储器44实施的)图像缓冲器和图形处理单元。图形处理单元可以通信耦合至图像缓冲器。图形处理单元可以包含通过逻辑电路47实施的解码器30，以实施参照图3和/或本文中所描述的任何其它解码器系统或子系统所论述的各种模块。
在一些实例中，天线42可以用于接收视频数据的经编码比特流。如所论述，经编码比特流可以包含本文所论述的与编码视频帧相关的数据、指示符、索引值、模式选择数据等，例如与编码分割相关的数据(例如，变换系数或经量化变换系数，(如所论述的)可选指示符，和/或定义编码分割的数据)。视频译码系统40还可包含耦合至天线42并用于解码经编码比特流的解码器30。显示设备45用于呈现视频帧。
应理解，本申请实施例中对于参考编码器20所描述的实例，解码器30可以用于执行相反过程。关于信令语法元素，解码器30可以用于接收并解析这种语法元素，相应地解码相关视频数据。在一些例子中，编码器20可以将语法元素熵编码成经编码视频比特流。在此类实例中，解码器30可以解析这种语法元素，并相应地解码相关视频数据。
需要说明的是，本申请实施例描述的方法主要用于视频编码中的图像划分过程，此过程在编码器20和解码器30均存在，本申请实施例中的编码器20和解码器30可以是例如H.263、H.264、HEVV、MPEG-2、MPEG-4、VP8、VP9等视频标准协议或者下一代视频标准协议(如H.266等)对应的编/解码器。
参见图2，图2示出用于实现本申请实施例的编码器20的实例的示意性/概念性结构框图，编码器20包括残差计算单元204、变换处理单元206、量化单元208、逆量化单元210、逆变换处理单元212、重构单元214、缓冲器216、环路滤波器单元220、经解码图片缓冲器(decoded picture buffer，DPB)230、预测处理单元260和熵编码单元270。预测处理单元260可以包含帧间预测单元244、帧内预测单元254和模式选择单元262。帧间预测单元244可以包含运动估计单元和运动补偿单元(未图示)。图2所示的编码器20也可以称为混合型视频编码器或根据混合型视频编解码器的视频编码器。
例如，残差计算单元204、变换处理单元206、量化单元208、预测处理单元260和熵编码单元270形成编码器20的前向信号路径，而例如逆量化单元210、逆变换处理单元212、重构单元214、缓冲器216、环路滤波器220、经解码图片缓冲器(decoded picture buffer，DPB)230、预测处理单元260形成编码器的后向信号路径，其中编码器的后向信号路径对应于解码器的信号路径(参见图3中的解码器30)。
编码器20通过例如输入202，接收图片201或图片201的图像块203，例如，形成视频或视频序列的图片序列中的图片。图像块203也可以称为当前图片块或待编码图片块，图片201可以称为当前图片或待编码图片(尤其是在视频编码中将当前图片与其它图片区分开时，其它图片例如同一视频序列亦即也包括当前图片的视频序列中的先前经编码和/或经解码图片)。
编码器20的实施例可以包括分割单元(图2中未绘示)，用于将图片201分割成多个例如图像块203的块，通常分割成多个不重叠的块。分割单元可以用于对视频序列中所有图片使用相同的块大小以及定义块大小的对应栅格，或用于在图片或子集或图片群组之间更改块大小，并将每个图片分割成对应的块。
在一个实例中，编码器20的预测处理单元260可以用于执行上述分割技术的任何组合。
如图片201，图像块203也是或可以视为具有采样值的采样点的二维阵列或矩阵，虽然其尺寸比图片201小。换句话说，图像块203可以包括，例如，一个采样阵列(例如黑白图片201情况下的亮度阵列)或三个采样阵列(例如，彩色图片情况下的一个亮度阵列和两个色度阵列)或依据所应用的色彩格式的任何其它数目和/或类别的阵列。图像块203的水平和垂直方向(或轴线)上采样点的数目定义图像块203的尺寸。
如图2所示的编码器20用于逐块编码图片201，例如，对每个图像块203执行编码和预测。
残差计算单元204用于基于图片图像块203和预测块265(下文提供预测块265的其它细节)计算残差块205，例如，通过逐样本(逐像素)将图片图像块203的样本值减去预测块265的样本值，以在样本域中获取残差块205。
变换处理单元206用于在残差块205的样本值上应用例如离散余弦变换(discrete cosine transform，DCT)或离散正弦变换(discrete sine transform，DST)的变换，以在变换域中获取变换系数207。变换系数207也可以称为变换残差系数，并在变换域中表示残差块205。
变换处理单元206可以用于应用DCT/DST的整数近似值，例如为HEVC/H.265指定的变换。与正交DCT变换相比，这种整数近似值通常由某一因子按比例缩放。为了维持经正变换和逆变换处理的残差块的范数，应用额外比例缩放因子作为变换过程的一部分。比例缩放因子通常是基于某些约束条件选择的，例如，比例缩放因子是用于移位运算的2的幂、变换系数的位深度、准确性和实施成本之间的权衡等。例如，在解码器30侧通过例如逆变换处理单元212为逆变换(以及在编码器20侧通过例如逆变换处理单元212为对应逆变换)指定具体比例缩放因子，以及相应地，可以在编码器20侧通过变换处理单元206为正变换指定对应比例缩放因子。
量化单元208用于例如通过应用标量量化或向量量化来量化变换系数207，以获取经量化变换系数209。经量化变换系数209也可以称为经量化残差系数209。量化过程可以减少与部分或全部变换系数207有关的位深度。例如，可在量化期间将n位变换系数向下舍入到m位变换系数，其中n大于m。可通过调整量化参数(quantization parameter，QP)修改量化程度。例如，对于标量量化，可以应用不同的标度来实现较细或较粗的量化。较小量化步长对应较细量化，而较大量化步长对应较粗量化。可以通过QP指示合适的量化步长。例如，量化参数可以为合适的量化步长的预定义集合的索引。例如，较小的量化参数可以对应精细量化(较小量化步长)，较大量化参数可以对应粗糙量化(较大量化步长)，反之亦然。量化可以包含除以量化步长以及例如通过逆量化210执行的对应的量化或逆量化，或者可以包含乘以量化步长。根据例如HEVC的一些标准的实施例可以使用量化参数来确定量化步长。一般而言，可以基于量化参数使用包含除法的等式的定点近似来计算量化步长。可以引入额外比例缩放因子来进行量化和反量化，以恢复可能由于在用于量化步长和量化参数的等式的定点近似中使用的标度而修改的残差块的范数。在一个实例实施方式中，可以合并逆变换和反量化的标度。或者，可以使用自定义量化表并在例如比特流中将其从编码器通过信号发送到解码器。量化是有损操作，其中量化步长越大，损耗越大。
逆量化单元210用于在经量化系数上应用量化单元208的逆量化，以获取经反量化系数211，例如，基于或使用与量化单元208相同的量化步长，应用量化单元208应用的量 化方案的逆量化方案。经反量化系数211也可以称为经反量化残差系数211，对应于变换系数207，虽然由于量化造成的损耗通常与变换系数不相同。
逆变换处理单元212用于应用变换处理单元206应用的变换的逆变换，例如，DCT或DST，以在样本域中获取逆变换块213。逆变换块213也可以称为逆变换经反量化块213或逆变换残差块213。
重构单元214(例如，求和器214)用于将逆变换块213(即经重构残差块213)添加至预测块265，以在样本域中获取经重构块215，例如，将经重构残差块213的样本值与预测块265的样本值相加。
可选地，例如线缓冲器216的缓冲器单元216(或简称“缓冲器”216)用于缓冲或存储经重构块215和对应的样本值，用于例如帧内预测。在其它的实施例中，编码器可以用于使用存储在缓冲器单元216中的未经滤波的经重构块和/或对应的样本值来进行任何类别的估计和/或预测，例如帧内预测。
例如，编码器20的实施例可以经配置以使得缓冲器单元216不只用于存储用于帧内预测254的经重构块215，也用于环路滤波器单元220(在图2中未示出)，和/或，例如使得缓冲器单元216和经解码图片缓冲器单元230形成一个缓冲器。其它实施例可以用于将经滤波块221和/或来自经解码图片缓冲器230的块或样本(图2中均未示出)用作帧内预测254的输入或基础。
环路滤波器单元220(或简称“环路滤波器”220)用于对经重构块215进行滤波以获取经滤波块221，从而顺利进行像素转变或提高视频质量。环路滤波器单元220旨在表示一个或多个环路滤波器，例如去块滤波器、样本自适应偏移(sample-adaptive offset，SAO)滤波器或其它滤波器，例如双边滤波器、自适应环路滤波器(adaptive loop filter，ALF)，或锐化或平滑滤波器，或协同滤波器。尽管环路滤波器单元220在图2中示出为环内滤波器，但在其它配置中，环路滤波器单元220可实施为环后滤波器。经滤波块221也可以称为经滤波的经重构块221。经解码图片缓冲器230可以在环路滤波器单元220对经重构编码块执行滤波操作之后存储经重构编码块。
编码器20(对应地，环路滤波器单元220)的实施例可以用于输出环路滤波器参数(例如，样本自适应偏移信息)，例如，直接输出或由熵编码单元270或任何其它熵编码单元熵编码后输出，例如使得解码器30可以接收并应用相同的环路滤波器参数用于解码。
经DPB 230可以为存储参考图片数据供编码器20编码视频数据之用的参考图片存储器。DPB 230可由多种存储器设备中的任一个形成，例如DRAM(包含同步DRAM(synchronous DRAM，SDRAM)、磁阻式RAM(magnetoresistive RAM，MRAM)、电阻式RAM(resistive RAM，RRAM))或其它类型的存储器设备。可以由同一存储器设备或单独的存储器设备提供DPB 230和缓冲器216。在某一实例中，经DPB 230用于存储经滤波块221。经解码图片缓冲器230可以进一步用于存储同一当前图片或例如先前经重构图片的不同图片的其它先前的经滤波块，例如先前经重构和经滤波块221，以及可以提供完整的先前经重构亦即经解码图片(和对应参考块和样本)和/或部分经重构当前图片(和对应参考块和样本)，例如用于帧间预测。在某一实例中，如果经重构块215无需环内滤波而得以重构，则经DPB 230用于存储经重构块215。
预测处理单元260，也称为块预测处理单元260，用于接收或获取图像块203(当前图片201的当前图像块203)和经重构图片数据，例如来自缓冲器216的同一(当前)图片 的参考样本和/或来自经解码图片缓冲器230的一个或多个先前经解码图片的参考图片数据231，以及用于处理这类数据进行预测，即提供可以为经帧间预测块245或经帧内预测块255的预测块265。
模式选择单元262可以用于选择预测模式(例如帧内或帧间预测模式)和/或对应的用作预测块265的预测块245或255，以计算残差块205和重构经重构块215。
模式选择单元262的实施例可以用于选择预测模式(例如，从预测处理单元260所支持的那些预测模式中选择)，所述预测模式提供最佳匹配或者说最小残差(最小残差意味着传输或存储中更好的压缩)，或提供最小信令开销(最小信令开销意味着传输或存储中更好的压缩)，或同时考虑或平衡以上两者。模式选择单元262可以用于基于码率失真优化(rate distortion optimization，RDO)确定预测模式，即选择提供最小码率失真优化的预测模式，或选择相关码率失真至少满足预测模式选择标准的预测模式。
下文将详细解释编码器20的实例(例如，通过预测处理单元260)执行的预测处理和(例如，通过模式选择单元262)执行的模式选择。
如上文所述，编码器20用于从(预先确定的)预测模式集合中确定或选择最好或最优的预测模式。预测模式集合可以包括例如帧内预测模式和/或帧间预测模式。
帧内预测模式集合可以包括35种不同的帧内预测模式，例如，如DC(或均值)模式和平面模式的非方向性模式，或如H.265中定义的方向性模式，或者可以包括67种不同的帧内预测模式，例如，如DC(或均值)模式和平面模式的非方向性模式，或如正在发展中的H.266中定义的方向性模式。
在可能的实现中，帧间预测模式集合取决于可用参考图片(即，例如前述存储在DBP230中的至少部分经解码图片)和其它帧间预测参数，例如取决于是否使用整个参考图片或只使用参考图片的一部分，例如围绕当前块的区域的搜索窗区域，来搜索最佳匹配参考块，和/或例如取决于是否应用如半像素和/或四分之一像素内插的像素内插，帧间预测模式集合例如可包括先进运动矢量(advanced motion vector prediction，AMVP)模式和融合(merge)模式。具体实施中，帧间预测模式集合可包括本申请实施例改进的基于控制点的AMVP模式，以及，改进的基于控制点的merge模式。在一个实例中，帧内预测单元254可以用于执行下文描述的帧间预测技术的任意组合。
除了以上预测模式，本申请实施例也可以应用跳过模式和/或直接模式。
预测处理单元260可以进一步用于将图像块203分割成较小的块分区或子块，例如，通过迭代使用四叉树分割、二叉树分割或三叉树(triple-tree，TT)分割，或其任何组合，以及用于例如为块分区或子块中的每一个执行预测，其中模式选择包括选择分割的图像块203的树结构和选择应用于块分区或子块中的每一个的预测模式。
帧间预测单元244可以包含运动估计(motion estimation，ME)单元(图2中未示出)和运动补偿(motion compensation，MC)单元(图2中未示出)。运动估计单元用于接收或获取图片图像块203(当前图片201的当前图片图像块203)和经解码图片231，或至少一个或多个先前经重构块，例如，一个或多个其它/不同先前经解码图片231的经重构块，来进行运动估计。例如，视频序列可以包括当前图片和先前经解码图片31，或换句话说，当前图片和先前经解码图片31可以是形成视频序列的图片序列的一部分，或者形成该图片序列。
例如，编码器20可以用于从多个其它图片中的同一或不同图片的多个参考块中选择 参考块，并向运动估计单元(图2中未示出)提供参考图片和/或提供参考块的位置(X、Y坐标)与当前块的位置之间的偏移(空间偏移)作为帧间预测参数。该偏移也称为运动向量(motion vector，MV)。
运动补偿单元用于获取帧间预测参数，并基于或使用帧间预测参数执行帧间预测来获取帧间预测块245。由运动补偿单元(图2中未示出)执行的运动补偿可以包含基于通过运动估计(可能执行对子像素精确度的内插)确定的运动/块向量取出或生成预测块。内插滤波可从已知像素样本产生额外像素样本，从而潜在地增加可用于编码图片块的候选预测块的数目。一旦接收到用于当前图片块的PU的运动向量，运动补偿单元246可以在一个参考图片列表中定位运动向量指向的预测块。运动补偿单元246还可以生成与块和视频条带相关联的语法元素，以供解码器30在解码视频条带的图片块时使用。
具体的，上述帧间预测单元244可向熵编码单元270传输语法元素，所述语法元素包括帧间预测参数(比如遍历多个帧间预测模式后选择用于当前块预测的帧间预测模式的指示信息)。可能应用场景中，如果帧间预测模式只有一种，那么也可以不在语法元素中携带帧间预测参数，此时解码端30可直接使用默认的预测模式进行解码。可以理解的，帧间预测单元244可以用于执行帧间预测技术的任意组合。
帧内预测单元254用于获取，例如接收同一图片的图片块203(当前图片块)和一个或多个先前经重构块，例如经重构相邻块，以进行帧内估计。例如，编码器20可以用于从多个(预定)帧内预测模式中选择帧内预测模式。
编码器20的实施例可以用于基于优化标准选择帧内预测模式，例如基于最小残差(例如，提供最类似于当前图片块203的预测块255的帧内预测模式)或最小码率失真。
帧内预测单元254进一步用于基于如所选择的帧内预测模式的帧内预测参数确定帧内预测块255。在任何情况下，在选择用于块的帧内预测模式之后，帧内预测单元254还用于向熵编码单元270提供帧内预测参数，即提供指示所选择的用于块的帧内预测模式的信息。在一个实例中，帧内预测单元254可以用于执行帧内预测技术的任意组合。
具体的，上述帧内预测单元254可向熵编码单元270传输语法元素，所述语法元素包括帧内预测参数(比如遍历多个帧内预测模式后选择用于当前块预测的帧内预测模式的指示信息)。可能应用场景中，如果帧内预测模式只有一种，那么也可以不在语法元素中携带帧内预测参数，此时解码端30可直接使用默认的预测模式进行解码。
熵编码单元270用于将熵编码算法或方案(例如，可变长度编码(variable length coding，VLC)方案、上下文自适应VLC(context adaptive VLC，CAVLC)方案、算术编码方案、上下文自适应二进制算术编码(context adaptive binary arithmetic coding，CABAC)、基于语法的上下文自适应二进制算术编码(syntax-based context-adaptive binary arithmetic coding，SBAC)、概率区间分割熵(probability interval partitioning entropy，PIPE)编码或其它熵编码方法或技术)应用于经量化残差系数209、帧间预测参数、帧内预测参数和/或环路滤波器参数中的单个或所有上(或不应用)，以获取可以通过输出272以例如经编码比特流21的形式输出的经编码图片数据21。可以将经编码比特流传输到视频解码器30，或将其存档稍后由视频解码器30传输或检索。熵编码单元270还可用于熵编码正被编码的当前视频条带的其它语法元素。
视频编码器20的其它结构变型可用于编码视频流。例如，基于非变换的编码器20可以在没有针对某些块或帧的变换处理单元206的情况下直接量化残差信号。在另一实施方 式中，编码器20可具有组合成单个单元的量化单元208和逆量化单元210。
应当理解的是，视频编码器20的其它的结构变化可用于编码视频流。例如，对于某些图像块或者图像帧，视频编码器20可以直接地量化残差信号而不需要经变换处理单元206处理，相应地也不需要经逆变换处理单元212处理；或者，对于某些图像块或者图像帧，视频编码器20没有产生残差数据，相应地不需要经变换处理单元206、量化单元208、逆量化单元210和逆变换处理单元212处理；或者，视频编码器20可以将经重构图像块作为参考块直接地进行存储而不需要经滤波器220处理；或者，视频编码器20中量化单元208和逆量化单元210可以合并在一起。环路滤波器220是可选的，以及针对无损压缩编码的情况下，变换处理单元206、量化单元208、逆量化单元210和逆变换处理单元212是可选的。应当理解的是，根据不同的应用场景，帧间预测单元244和帧内预测单元254可以是被选择性的启用。
参见图3，图3示出用于实现本申请实施例的解码器30的实例的示意性/概念性框图。视频解码器30用于接收例如由编码器20编码的经编码图片数据(例如，经编码比特流)21，以获取经解码图片231。在解码过程期间，视频解码器30从视频编码器20接收视频数据，例如表示经编码视频条带的图片块的经编码视频比特流及相关联的语法元素。
在图3的实例中，解码器30包括熵解码单元304、逆量化单元310、逆变换处理单元312、重构单元314(例如求和器314)、缓冲器316、环路滤波器320、经解码图片缓冲器330以及预测处理单元360。预测处理单元360可以包含帧间预测单元344、帧内预测单元354和模式选择单元362。在一些实例中，视频解码器30可执行大体上与参照图2的视频编码器20描述的编码遍次互逆的解码遍次。
熵解码单元304用于对经编码图片数据21执行熵解码，以获取例如经量化系数309和/或经解码的编码参数(图3中未示出)，例如，帧间预测、帧内预测参数、环路滤波器参数和/或其它语法元素中(经解码)的任意一个或全部。熵解码单元304进一步用于将帧间预测参数、帧内预测参数和/或其它语法元素转发至预测处理单元360。视频解码器30可接收视频条带层级和/或视频块层级的语法元素。
逆量化单元310功能上可与逆量化单元110相同，逆变换处理单元312功能上可与逆变换处理单元212相同，重构单元314功能上可与重构单元214相同，缓冲器316功能上可与缓冲器216相同，环路滤波器320功能上可与环路滤波器220相同，经解码图片缓冲器330功能上可与经解码图片缓冲器230相同。
预测处理单元360可以包括帧间预测单元344和帧内预测单元354，其中帧间预测单元344功能上可以类似于帧间预测单元244，帧内预测单元354功能上可以类似于帧内预测单元254。预测处理单元360通常用于执行块预测和/或从经编码数据21获取预测块365，以及从例如熵解码单元304(显式地或隐式地)接收或获取预测相关参数和/或关于所选择的预测模式的信息。
当视频条带经编码为经帧内编码(I)条带时，预测处理单元360的帧内预测单元354用于基于信号表示的帧内预测模式及来自当前帧或图片的先前经解码块的数据来产生用于当前视频条带的图片块的预测块365。当视频帧经编码为经帧间编码(即B或P)条带时，预测处理单元360的帧间预测单元344(例如，运动补偿单元)用于基于运动向量及从熵解码单元304接收的其它语法元素生成用于当前视频条带的视频块的预测块365。对于帧间预测，可从一个参考图片列表内的一个参考图片中产生预测块。视频解码器30可 基于存储于DPB 330中的参考图片，使用默认建构技术来建构参考帧列表：列表0和列表1。
预测处理单元360用于通过解析运动向量和其它语法元素，确定用于当前视频条带的视频块的预测信息，并使用预测信息产生用于正经解码的当前视频块的预测块。在本申请的一实例中，预测处理单元360使用接收到的一些语法元素确定用于编码视频条带的视频块的预测模式(例如，帧内或帧间预测)、帧间预测条带类型(例如，B条带、P条带或GPB条带)、用于条带的参考图片列表中的一个或多个的建构信息、用于条带的每个经帧间编码视频块的运动向量、条带的每个经帧间编码视频块的帧间预测状态以及其它信息，以解码当前视频条带的视频块。在本公开的另一实例中，视频解码器30从比特流接收的语法元素包含接收自适应参数集(adaptive parameter set，APS)、序列参数集(sequence parameter set，SPS)、图片参数集(picture parameter set，PPS)或条带标头中的一个或多个中的语法元素。
逆量化单元310可用于逆量化(即，反量化)在比特流中提供且由熵解码单元304解码的经量化变换系数。逆量化过程可包含使用由视频编码器20针对视频条带中的每一视频块所计算的量化参数来确定应该应用的量化程度并同样确定应该应用的逆量化程度。
逆变换处理单元312用于将逆变换(例如，逆DCT、逆整数变换或概念上类似的逆变换过程)应用于变换系数，以便在像素域中产生残差块。
重构单元314(例如，求和器314)用于将逆变换块313(即经重构残差块313)添加到预测块365，以在样本域中获取经重构块315，例如通过将经重构残差块313的样本值与预测块365的样本值相加。
环路滤波器单元320(在编码循环期间或在编码循环之后)用于对经重构块315进行滤波以获取经滤波块321，从而顺利进行像素转变或提高视频质量。在一个实例中，环路滤波器单元320可以用于执行下文描述的滤波技术的任意组合。环路滤波器单元320旨在表示一个或多个环路滤波器，例如去块滤波器、SAO滤波器或其它滤波器，例如双边滤波器、ALF，或锐化或平滑滤波器，或协同滤波器。尽管环路滤波器单元320在图3中示出为环内滤波器，但在其它配置中，环路滤波器单元320可实施为环后滤波器。
随后将给定帧或图片中的经解码视频块321存储在存储用于后续运动补偿的参考图片的经解码图片缓冲器330中。
解码器30用于例如，藉由输出332输出经解码图片31，以向用户呈现或供用户查看。
视频解码器30的其它变型可用于对压缩的比特流进行解码。例如，解码器30可以在没有环路滤波器单元320的情况下生成输出视频流。例如，基于非变换的解码器30可以在没有针对某些块或帧的逆变换处理单元312的情况下直接逆量化残差信号。在另一实施方式中，视频解码器30可以具有组合成单个单元的逆量化单元310和逆变换处理单元312。
具体的，在本申请实施例中，解码器30用于实现后文实施例中描述的视频解码方法。
应当理解的是，视频解码器30的其它结构变化可用于解码经编码视频位流。例如，视频解码器30可以不经滤波器320处理而生成输出视频流；或者，对于某些图像块或者图像帧，视频解码器30的熵解码单元304没有解码出经量化的系数，相应地不需要经逆量化单元310和逆变换处理单元312处理。环路滤波器320是可选的；以及针对无损压缩的情况下，逆量化单元310和逆变换处理单元312是可选的。应当理解的是，根据不同的应用场景，帧间预测单元和帧内预测单元可以是被选择性的启用。
应当理解的是，本申请的编码器20和解码器30中，针对某个环节的处理结果可以经过进一步处理后，输出到下一个环节，例如，在插值滤波、运动矢量推导或环路滤波等环节之后，对相应环节的处理结果进一步进行Clip或移位shift等操作。
例如，按照相邻仿射编码块的运动矢量推导得到的当前图像块的控制点的运动矢量，或者推导得到的当前图像块的子块的运动矢量，可以经过进一步处理，本申请对此不做限定。例如，对运动矢量的取值范围进行约束，使其在一定的位宽内。假设允许的运动矢量的位宽为bitDepth，则运动矢量的范围为-2 bitDepth-1～2 bitDepth-1-1。如bitDepth为16，则取值范围为-32768～32767。如bitDepth为18，则取值范围为-131072～131071。又例如，对运动矢量(例如一个8×8图像块内的四个4×4子块的运动矢量MV)的取值进行约束，使得所述四个4×4子块MV的整数部分之间的最大差值不超过N个像素，例如不超过一个像素。
参见图4，图4是本申请实施例提供的视频译码设备400(例如视频编码设备400或视频解码设备400)的结构示意图，视频译码设备400适于实施本文所描述的实施例。在一个实施例中，视频译码设备400可以是视频解码器(例如图1A的解码器30)或视频编码器(例如图1A的编码器20)。在另一个实施例中，视频译码设备400可以是上述图1A的解码器30或图1A的编码器20中的一个或多个组件。
视频译码设备400包括：用于接收数据的入口端口410和接收器(Rx)420，用于处理数据的处理器430、逻辑单元或中央处理器(CPU)，用于传输数据的发送器(Tx)440和出口端口450，以及，用于存储数据的存储器460。视频译码设备400还可以包括与入口端口410、接收器420、发送器440和出口端口450耦合的光电转换组件和电光(EO)组件，用于光信号或电信号的出口或入口。
处理器430通过硬件和软件实现。处理器430可以实现为一个或多个CPU芯片、核(例如，多核处理器)、FPGA、ASIC和DSP。处理器430与入口端口410、接收器420、发送器440、出口端口450和存储器460通信。处理器430包括译码模块470(例如编码模块470或解码模块470)。编码/解码模块470实现本文中所公开的实施例，以实现本申请实施例所提供的视频解码方法。例如，编码/解码模块470实现、处理或提供各种编码操作。因此，通过编码/解码模块470为视频译码设备400的功能提供了实质性的改进，并影响了视频译码设备400到不同状态的转换。或者，以存储在存储器460中并由处理器430执行的指令来实现编码/解码模块470。
存储器460包括一个或多个磁盘、磁带机和固态硬盘，可以用作溢出数据存储设备，用于在选择性地执行这些程序时存储程序，并存储在程序执行过程中读取的指令和数据。存储器460可以是易失性和/或非易失性的，可以是ROM、RAM、随机存取存储器(ternary content-addressable memory，TCAM)和/或SRAM。
参见图5，图5是根据一示例性实施例的可用作图1A中的源设备12和目的地设备14中的任一个或两个的装置500的简化框图。装置500可以实现本申请的技术。换言之，图5为本申请实施例的编码设备或解码设备(简称为译码设备500)的一种实现方式的示意性框图。其中，译码设备500可以包括处理器510、存储器530和总线系统550。其中，处理器和存储器通过总线系统相连，该存储器用于存储指令，该处理器用于执行该存储器存储的指令。译码设备的存储器存储程序代码，且处理器可以调用存储器中存储的程序代码执行本申请描述的各种视频编码或解码方法。为避免重复，这里不再详细描述。
在本申请实施例中，该处理器510可以是中央处理单元(central processing unit，CPU)，该处理器510还可以是其他通用处理器、DSP、ASIC、FPGA或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
该存储器530可以包括ROM设备或者RAM设备。任何其他适宜类型的存储设备也可以用作存储器530。存储器530可以包括由处理器510使用总线550访问的代码和数据531。存储器530可以进一步包括操作系统533和应用程序535，该应用程序535包括允许处理器510执行本申请描述的视频编码或解码方法(尤其是本申请描述的视频解码方法)的至少一个程序。例如，应用程序535可以包括应用1至N，其进一步包括执行在本申请描述的视频编码或解码方法的视频编码或解码应用(简称视频译码应用)。
该总线系统550除包括数据总线之外，还可以包括电源总线、控制总线和状态信号总线等。但是为了清楚说明起见，在图中将各种总线都标为总线系统550。
可选的，译码设备500还可以包括一个或多个输出设备，诸如显示器570。在一个示例中，显示器570可以是触感显示器，其将显示器与可操作地感测触摸输入的触感单元合并。显示器570可以经由总线550连接到处理器510。
图1A所示的源设备12和目的设备14，图1B所示的视频编码系统40以及图4和图5所述的视频译码设备中的任意一个设备，在视频编码的过程中可以采用QT划分方式、BT划分方式以及EQT划分方式等划分方式。
其中，QT是一种树状结构，表示一个节点可划分为四个子节点。现有视频编码标准采用基于四叉树的CTU划分方式：CTU作为根节点，每个节点对应于一个方形的区域；一个节点可以不再划分(此时它对应的区域为一个CU)，或者将这个节点划分成四个下一层级的节点，即把这个方形区域划分成四个大小相同的方形区域(其长、宽各为划分前区域长、宽的一半)，每个区域对应于一个节点，如图6中(a)所示。
BT是一种树状结构，表示一个节点可划分成两个子节点。现有采用二叉树的编码方法中，一个二叉树结构上的节点可以不划分，或者把此节点划分成两个下一层级的节点。划分成两个节点的方式有两种：1)HBT，将节点对应的区域划分成上、下两个相同大小的区域，每个区域对应于一个节点，如图6中(b)所示；或者2)VBT，将节点对应的区域划分成左、右两个大小相同的区域，每个区域对应于一个节点，如图6中(c)所示。
EQT是一种工字划分结构，一个节点可划分成四个子节点。划分成四个节点的方式有两种：1)HEQT，将节点对应的区域划分成上、中、下三个区域，每个区域对应于一个节点，其中上、中左、中右、下四个区域的高分别为节点高的1/4、1/2、1/2、1/4，中左和中右宽度为节点高度的1/2、1/2，如图6中(d)所示；或者2)VEQT，将节点对应的区域划分成左、中上、中下、右三个区域，每个区域对应于一个节点，其中左、中上、中下、右四个区域的宽分别为节点高的1/4、1/2、1/2、1/4，中上和中下宽度为节点高度的1/2、1/2，如图6中(e)所示。现有采用扩展四叉树的编码方法中，一个扩展四叉树结构上的节点可以不划分，或者把此节点按BT或EQT的方式继续划分成下一层级的节点。
H.265视频编码标准把一帧图像分割成互不重叠的编码树单元(CTU)，CTU的大小可设置为64×64(CTU的大小也可设置为其它值，如JVET参考软件JEM中CTU大小增大为128×128或256×256)。64×64的CTU包含由64列、每列64个像素的矩形像素点阵，每个像素包含亮度分量或/和色度分量。使用QT的CTU划分方法，将CTU作为四叉树的 根节点(root)，按照四叉树的划分方式，将CTU递归划分成若干个叶节点(leaf node)。一个节点对应于一个图像区域，节点如果不划分，则节点称为叶节点，它对应的图像区域形成一个CU；如果节点继续划分，则节点对应的图像区域划分成四个相同大小的区域(其长和宽各为被划分区域的一半)，每个区域对应一个节点，需要分别确定这些节点是否还会划分。在解码端，一个节点是否划分由码流中这个节点对应的划分标志位split_cu_flag指示。一个节点A划分一次得到4个节点Bi，i＝0,1,2,3，Bi称为A的子节点，A称为Bi的父节点。根节点的四叉树层级(qtDepth)为0，节点的四叉树层级为节点的父节点的四叉树层级加1。为表述简洁，下文中节点的大小和形状即指节点对应的图像区域的大小和形状。
例如，对64×64的CTU节点(四叉树层级为0)，根据它对应的split_cu_flag，可选择不划分，成为1个64×64的CU，或者选择划分为4个32×32的节点(四叉树层级为1)。这四个32×32的节点中的每一个节点，又可以根据它对应的split_cu_flag，选择继续划分或者不划分；如果一个32×32的节点继续划分，则产生四个16×16的节点(四叉树层级为2)。以此类推，直到所有节点都不再划分，这样一个CTU就被划分成一组CU。CU的最小尺寸(size)在序列参数集(Sequence Parameter Set，SPS)中标识，例如8×8为最小CU。在上述递归划分过程中，如果一个节点的尺寸等于最小CU尺寸(minimum CU size)，这个节点默认为不再划分，同时也不需要在码流中包含它的划分标志位。当解析到一个节点为叶节点后，此叶节点为一个CU，解码端设备进一步解析CU对应的编码信息(包括CU的预测模式、变换系数等信息，例如H.265中的coding_unit()语法结构体)，然后按照这些编码信息对CU进行预测、反量化、反变换、环路滤波等解码处理，产生这个CU对应的重建图像。四叉树结构使得CTU能够根据图像局部特点划分成合适大小的一组CU，例如平滑区域划分成较大的CU，而纹理丰富区域划分为较小的CU。
多用途视频编码测试模型(versatile video coding test model，VTM)参考软件在四叉树划分的基础上，增加了二叉树(binary tree，BT)划分方式和三叉树(ternary tree，TT)划分方式。其中，VTM是JVET组织开发的新式编解码器参考软件。图7给出了使用QT-MTT将一个CTU划分成a到p等16个CU的示例。图7右图中每个端点表示一个节点，一个节点连出4根线表示四叉树划分，一个节点连出2根线表示二叉树划分，一个节点连出3根线表示三叉树划分。实线表示QT划分，虚线表示多类型划分(Multi-Type Tree，MTT)的第一层划分，点划线表示MTT的第二层划分。a到p为16个MTT叶节点，每个MTT叶节点为1个CU。一个CTU按照图7右图的划分方式，得到了如图7左图所示的CU划分图。
QT-MTT划分方式中，每个CU具有QT层级(quad-tree depth，QT depth，也称为QT深度)和MTT层级(multi-type tree depth，MTT depth，也称为MTT深度)。QT层级表示CU所属的QT叶节点的QT层级，MTT层级表示CU所属MTT叶节点的MTT层级。编码树的根节点的QT层级为0，MTT层级为0。如果编码树上一个节点使用QT划分，则划分得到的子节点的QT层级为该节点的QT层级加1，MTT层级不变；相似的，如果编码树上一个节点使用MTT划分(即BT或TT划分之一)，则划分得到的子节点的MTT层级为该节点的MTT层级加1，QT层级不变。例如图7中a、b、c、d、e、f、g、i、j的QT层级为1，MTT层级为2；h的QT层级为1，MTT层级为1；n、o、p的QT层级为2，MTT层级为0；l、m的QT层级为2，MTT层级为1。如果CTU只划分成一个CU，则此 CU的QT层级为0，MTT层级为0。
AVS3中使用了QT级联BT/EQT的划分方式，即第一级编码树上的节点只能使用QT划分成子节点，第一级编码树的叶节点为第二级编码树的根节点；第二级编码树上的节点可使用BT或EQT划分方式中的一种划分为子节点；第二级编码树的叶节点为编码单元。需要注意的是，当叶节点为BT或EQT划分方式时，其叶节点只能使用BT或EQT划分方式，而不能使用QT的方式。
经过上述的各种划分之后，编码树下的叶子节点位置的图像块作为编码单元，视频编码主要包括帧内预测(Intra Prediction)、帧间预测(Inter Prediction)、变换(Transform)、量化(Quantization)、熵编码(Entropy encode)、环内滤波(in-loop filtering)(主要为去块滤波，de-blocking filtering)等环节。将图像划分为编码块之后进行帧内预测或者帧间预测，并且在得到残差之后进行变换量化，最终进行熵编码并输出码流。此处编码块为由像素点组成的M×N大小的阵列(M可以等于N，也可以不等于N)，并且已知各个像素点位置的像素值。
帧内预测是指利用当前图像内已重建区域内像素点的像素值对当前编码块内像素点的像素值进行预测。
帧间预测是在已重建的图像中，为当前图像中的当前编码块寻找匹配的参考块，从而得到当前编码块的运动信息，然后根据运动信息计算出当前编码块中像素点的像素值的预测信息或者预测值(以下不再区分信息和值)。其中，计算运动信息的过程称为运动估计(Motion estimation，ME)，计算出当前编码块中像素点的像素值的预测值的过程称为运动补偿(Motion compensation，MC)。
需要说明的是，当前编码块的运动信息包括了预测方向的指示信息(通常为前向预测、后向预测或者双向预测)，一个或两个指向参考块的运动矢量(motion vector，MV)，以及参考块所在图像的指示信息(通常记为参考帧索引，Reference index)。
前向预测是指当前编码块从前向参考图像集合中选择一个参考图像获取参考块。后向预测是指当前编码块从后向参考图像集合中选择一个参考图像获取参考块。双向预测是指从前向和后向参考图像集合中各选择一个参考图像获取参考块。当使用双向预测方法时，当前编码块会存在两个参考块，每个参考块各自需要运动矢量和参考帧索引进行指示，然后根据两个参考块内像素点的像素值确定当前块内像素点像素值的预测值。
运动估计过程需要为当前编码块在参考图像中尝试多个参考块，最终使用哪一个或者哪几个参考块用作预测则使用率失真优化(Rate-distortion optimization，RDO)或者其他方法确定。
利用帧内预测或者帧间预测得到预测信息之后，当前编码块内像素点的像素值减去对应的预测信息便得到残差信息，然后利用离散余弦变换(Discrete Cosine Transformation，DCT)等方法对残差信息进行变换，再使用量化熵编码得到码流。预测信号加上重建残差信号之后需进一步进行滤波操作，进而得到重建信号，并将其作为后续编码的参考信号。
解码则相当于编码的逆过程。例如，首先利用熵解码反量化反变换得到残差信息，解码码流以确定当前编码块使用的是帧内预测还是帧间预测。如果是帧内预测，则利用周围已重建区域内像素点的像素值按照所使用的帧内预测方法构建预测信息。如果是帧间预测，则需要解析出运动信息，并使用所解析出的运动信息在已重建的图像中确定参考块，并将块内像素点的像素值作为预测信息，此过程称为运动补偿(Motion compensation，MC)。 使用预测信息加上残差信息经过滤波操作便可以得到重建信息。
参见图8，本申请提供了一种图像划分方法，应用于视频编码(包括编码和解码)过程，该方法可由源设备12、目的设备14、视频编码器20视频解码器30、视频译码设备400或者视频译码设备500执行。该方法主要包括以下步骤：
S801：获取当前图像块的块信息。
其中，当前图像块可以是当前图像划分出的一个图像块，对应于当前图像的编码树上的一个节点，当前图像块也可以是当前图像的一个LCU(例如，在HEVC标准中的CTU)，也可以是以LCU为根节点划分得到的子块，还可以是以某一层级的子块为根节点划分得到的下一层级的子块。
当前图像块的块信息可以包括当前图像块的尺寸信息，例如当前图像块的宽度、当前图像块的高度或者基于当前图像块的宽度和高度得到的面积。当前图像块的块信息还可以包括当前图像块中像素点的坐标，例如当前图像块中像素点在图像坐标系中的坐标，其中，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向(x轴)，图像坐标系的纵轴为当前图像块所在的图像的高度方向(y轴)。进一步地，当前图像的块信息还可以包括当前图像块对应的其他图像相关信息，例如，当前图像块是否超出当前图像的边界，对于视频解码端设备这些块信息能够从当前图像的码流中解析或者推导得到。
具体地，可以通过以下方法判断当前图像块是否超出当前图像块所在图像的边界：根据图像块的块信息，获得当前图像块中的一个像素点的坐标(x，y)；判断像素点的坐标(x，y)是否满足预设条件，若像素点的坐标(x，y)满足第一预设条件，则表明当前图像块出当前图像块所在图像的右边界，若像素点的坐标(x，y)满足第二预设条件，则表明图像块超出当前图像块所在图像的下边界，若像素点的坐标(x，y)满足第三预设条件，则表明当前图像块超出当前图像块所在图像的右边界且超出当前图像的下边界(简称右下边界)，若像素点的坐标(x，y)满足第四预设条件，则表明当前图像块超出当前图像块所在图像的边界，也即，图片可能超出了图像的下边界，或者超出图像的右边界，或者超出了图像的右下边界。另外，若像素点的坐标(x，y)满足第四预设条件，但不满足第一预设条件和第二预设条件，则表明当前图像块超出当前图像块所在图像的右下边界。
其中，所选择的像素点用于表征当前图像块，可以选取当前图像块中特定的像素点来表示当前图像块，如选取当前图像块的顶点的像素点，如左上顶点的像素点、右上顶点的像素点、左下顶点的像素点或者右下顶点的像素点，当然，还可以选取当前图像块的中心位置的像素点，还可以选取当前图像块中除上述像素点外的任意一个像素点。上述的第一预设条件、第二预设条件、第三预设条件以及第四预设条件则可根据所选择的像素点的位置、当前图像块所在图像的尺寸确定。
进一步地，当所选择的像素点的坐标(x，y)为当前图像块中的左上顶点的像素点相对于当前图像块所在图像左上顶点像素位置的坐标时，第一预设条件为：像素点的坐标(x，y)满足x+width>PicWidth，且y+height≤PicHeight；第二预设条件为：像素点的坐标(x，y)满足x+width≤PicWidth，且y+height>PicHeight；第三预设条件为：像素点的坐标(x，y)满足x+width>PicWidth，且y+height>PicHeight；第四预设条件为：像素点的坐标(x，y)满足x+width>PicWidth，或y+height>PicHeight。 其中，width为当前图像块的宽度，height为当前图像块的高度，PicWidth为当前图像块所在图像的宽度，PicHeight为当前图像块所在图像的高度。
S802：根据获取到的块信息，从候选划分方式集合中确定可用划分方式。
其中，候选划分方式集合包括但不限于不划分方式、水平二叉树HBT划分方式，垂直二叉树VBT划分方式，水平扩展四叉树HEQT划分方式，垂直扩展四叉树VEQT划分方式以及四叉树QT划分方式中的一种或多种。
S803：从确定出的可用划分方式中，确定当前图像块的划分方式。
对于解码端设备，可以通过以下方式从确定出的可用划分方式中，确定当前图像块的划分方式：当可用划分方式为一种时，将可用划分方式确定为当前图像块的划分方式；当可用划分方式为多种时，根据确定出的可用划分方式，解析包括当前图像块的码流，并根据解析结果确定当前图像块的划分方式。
具体地，可用划分方式的确定，是通过比较当前图像块的尺寸与各个候选划分方式所对应划分约束条件，如果所述当前图像块的尺寸满足候选划分方式所对应的划分约束条件，则所述的候选划分模式可用。若QT划分方式可用，且候选划分方式集合中除QT划分方式外的所有划分方式均不可用，则当前图像块的划分方式为QT划分方式。若QT划分方式可用，且候选划分方式集合中除QT划分方式外的至少一个划分方式可用，则解析码流以确定当前图像块的划分方式。若不划分方式可用，且候选划分方式集合中除不划分方式和QT划分方式外的所有划分方式均不可用，则当前图像块的划分方式为不划分方式。若不划分方式可用，且候选划分方式集合中除不划分方式和所述QT划分方式外的至少一个划分方式可用，则解析码流以确定所述当前图像块的划分方式。
例如，解码端设备从码流中解析二叉树扩展四叉树划分标识bet_split_flag，bet_split_flag值为1表示应使用二叉树扩展四叉树划分进行图像划分，值为0表示不应进行二叉树扩展四叉树行划分。如果bet_split_flag值为1，继续解析用于指示当前图像块的划分类型的标识bet_split_type_flag，bet_split_type_flag值为0表示进行二叉树扩展四叉树划分时应使用BT划分方式，值为1表示进行二叉树扩展四叉树划分时应使用EQT划分方式；再解析用于指示当前图像块的划分方向的标识bet_split_dir_flag，bet_split_dir_flag值为1表示进行二叉树扩展四叉树划分时应使用垂直划分，值为0表示进行二叉树扩展四叉树划分时应使用水平划分。
对于编码端设备，可以通过以下方式从确定出的可用划分方式中，确定当前图像块的划分方式：当可用划分方式为一种时，将可用划分方式确定为当前图像块的划分方式；当可用划分方式为多种时，分别确定每个可用划分方式的率失真代价(ratio distortion cost)，将可用划分方式中率失真代价最小的可用划分方式，确定为当前图像块的划分方式。
S804：根据当前图像块的划分方式，从当前图像块得到一个CU或多个CU。其中，每个CU的宽高比满足设定的CU的最大宽高比。
其中，当当前图像块的划分方式为不划分方式时，当前图像块为一个CU；当当前图像块的划分方式为不划分方式外的任一划分方式时，根据当前图像块的划分方式对当前图像块进行划分，若划分得到的子块的至少一个边长为T，T为4或8，则子块为一个CU，否则对该子块重复上述步骤S802和S803，继续确定划分方式，将当前图像块递归划分为多个CU。进一步地，设定的CU的最大宽高比可以为4或者8。
在步骤S802中，根据所述块信息，从候选划分方式集合中确定可用划分方式，包括 但不限于以下几种方式中的一种或多种：
方式一、根据块信息，判断当前图像块是否满足第一条件，当当前图像块满足第一条件时，确定VBT划分方式为可用划分方式。其中，第一条件为width>height*MaxPartRatio，width为当前图像块的宽度，height为当前图像块的高度，MaxPartRatio为设定的CU的最大宽高比。需要说明的是，本申请实施例中“*”表示相乘。
通过上述方案，相较于现有技术，本申请放宽了使用VBT划分方式的条件，在当前图像块的宽度于高度的比值大于设定的CU的最大宽高比时，可以采用进VBT划分方式，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
方式二、根据块信息，判断当前图像块是否满足第二条件；当当前图像块满足所述第二条件时，确定HBT划分方式为可用划分方式。其中，第二条件为height>width*MaxPartRatio，width为当前图像块的宽度，height为当前图像块的高度，MaxPartRatio为设定的CU的最大宽高比。
通过上述方案，相较于现有技术，本申请放宽了使用HBT划分方式的条件，在当前图像块的高度与宽度的比值大于设定的CU的最大宽高比时，可以采用进HBT划分方式，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
方式三、根据块信息，判断当前图像块是否满足第一条件集合中的条件；当当前图像块满足第一条件集合中的所有条件时，确定VEQT划分方式为可用划分方式。其中，第一条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)height≥MinEqtSize*2；(4)width≥MinEqtSize*4；(5)height*4≤MaxPartRatio*width；(6)height*MaxPartRatio≥width；其中，width为当前图像块的宽度，height为当前图像块的高度，MaxEqtSize为设定的最大EQT的尺寸，MinEqtSize为设定的最小EQT的尺寸，MaxPartRatio为设定的CU的最大宽高比。
通过上述方案，相较于现有技术，本申请紧缩了使用VEQT划分方式的条件，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
方式四、根据块信息，判断当前图像块是否满足第二条件集合中的条件；当当前图像块满足所述第二条件集合中的所有条件时，确定HEQT划分方式为可用划分方式。其中，第二条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)width≥MinEqtSize*2；(4)height≥MinEqtSize*4；(5)width*4≤MaxPartRatio*height；(7)width*MaxPartRatio≥height；其中，width为当前图像块的宽度，heigh为当前图像块的高度，MaxEqtSize为最大EQT的尺寸，MinEqtSize为最小EQT的尺寸，MaxPartRatio为CU的最大宽高比。
通过上述方案，相较于现有技术，本申请紧缩了使用HEQT划分方式的条件，以尽量避免出现宽高比不满足设定的最大CU宽高比的图像块(必须划分但无法划分的图像块)，提高编码性能。
进一步地，在上述方式一到方式五中，判断当前图像块是否满足相应的条件(或条件集合)之前，还要根据当前图像块的块信息，确定当前图像块在当前图像块所在的图像的 边界内。其中，具体可以通过以下步骤确定当前图像块在当前图像块的边界内：根据当前图像块的块信息，判断当前图像块是否满足第三条件；当当前图像块满足所述第三条件时，确定当前图像块在当前图像块的边界内。其中，第三条件为：(x0+width)≤PicWidth，且(y0+height)≤PicHeight，x0为图像坐标系中当前图像块左上顶点的像素点的横坐标，y0为图像坐标系中当前图像块左上顶点的像素点的纵坐标，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向，图像坐标系的纵轴为当前图像块所在的图像的高度方向，PicWidth为当前图像块所在的图像的宽度，PicHeight为当前图像块所在的图像的高度，如图9所示。
在具体实施过程中，上述方式一到方式五可以通过如表2所示的编码树定义语法实现，其中，表2中主要示出了与现有技术采用的编码树定义不同的部分，其它部分可以参照表1所示的编码树定义语法。
表2 本申请提供的编码树定义语法之一
Figure PCTCN2020087289-appb-000004
Figure PCTCN2020087289-appb-000005
当当前图像块超出当前图像块所在图像的边界时，可以采用现有技术中的方式确定候选可划分方式集合中的可用划分方式，例如，当当前图像块超出当前图像块所在图像的边界时，可以采用如表1所示的编码树定义语法判断候选可划分方式集合中的可用划分方式是否可用。
当MaxBTSize和MaxEqtSize设置为小于64时，按照现有的编码树定义语法会导致边界LCU划分得到的N×64或64×N(N<64)的图像无法继续划分，从较大的影响到编码性能。例如MaxBTSize和MaxEqtSize均设置为8时，在边界CTU中划分产生的16x64的块不能继续划分，又如，在边界LCU中通过BT划分产生的64x64的块不能继续划分。为了解决这一问题，本申请提供的图像划分方法还包括，根据当前图像块的块信息确定当前图像块超出当前图像块所在图像的边界，并根据当前图像块的块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断QT划分方式是否为可用划分方式。
其中，具体可以通过以下方法确定当前图像块超出当前图像块所在图像的边界：根据当前图像块的块信息，判断当前图像块是否满足第四条件；当当前图像块满足所述第四条件时，确定当前图像块超出当前图像块的边界。其中，第四条件为：(x0+width)＞PicWidth，且(y0+height)＞PicHeight，x0为图像坐标系中当前图像块左上顶点的像素点的横坐标，y0为图像坐标系中当前图像块左上顶点的像素点的纵坐标，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向，图像坐标系的纵轴为当前图像块所在的图像的高度方向，PicWidth为当前图像块所在的图像的宽度，PicHeight为当前图像块所在的图像的高度。
具体地，当当前图像块超出当前图像块所在图像的边界时，可以通过以下方式中的任意一种判断QT划分方式是否为可用划分方式：
方式A、根据图像块的块信息，判断当前图像块是否满足第三条件集合中的条件；若当前图像块满足第三条件集合中的至少一个条件，则QT划分方式为可用划分方式。
其中，第三条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
方式B、根据图像块的块信息，判断当前图像块是否满足第四条件集合中的条件；若当前图像块满足第四条件集合中的至少一个条件，则QT划分方式为可用划分方式。
其中，所述第四条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)当前图像块未超出图像块所在图像的右边界，且未超出图像块所在图像的下边界，即当前图像块超出当前图像块所在图像的右下边界；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
通过上述方式A或者方式B，在图像划分过程中，当当前图像块超出图像块所在图像的边界时采用QT划分方式，避免对边界图像块划分得到N×64或64×N(N<64)的图像块，进而避免当MaxBTSize和MaxEqtSize设置为小于64时，N×64或64×N(N<64)的图像块无法继续划分的问题。也就是说，在图像划分过程中，当当前图像块超出图像块所在图像的边界时，当当前图像块满足上述第三条件集合或者第四条件集合中的任意一个条件时，候选划分方式集合中除QT划分方式外的其它划分方式均不可用，当当前图像只能采用QT划分方式，因而可以避免对边界图像块划分得到N×64或64×N(N<64)的图像块，进而避免当MaxBTSize和MaxEqtSize设置为小于64时，N×64或64×N(N<64)的图像块无法继续划分的问题。
具体地，当第三条件集合中包括的条件为(1)，或者第四条件集合中包括的条件为(1)和(11)时，可以采用如表3所示的编码树定义语法实现；当第三条件集合中包括的条件为(6)，或者第四条件集合中包括的条件为(6)和(11)时，可以采用如表4所示的编码树定义语法实现；当第三条件集合中包括的条件为(7)，或者第四条件集合中包括的条件为(7)和(11)时，可以采用如表5所示的编码树定义语法实现；当第三条件集合中包括的条件为(9)，或者第四条件集合中包括的条件为(9)和(11)时，可以采用如表6所示的编码树定义语法实现。其中，表3～表6中主要示出了与现有技术采用的编码树定义不同的部分，其它部分可以参照表1所示的编码树定义语法或者参照表2所示的编码树定义语法。
表3 本申请提供的编码树定义语法二
Figure PCTCN2020087289-appb-000006
Figure PCTCN2020087289-appb-000007
表4 本申请提供的编码树定义语法之三
Figure PCTCN2020087289-appb-000008
表5 本申请提供的编码树定义语法之四
Figure PCTCN2020087289-appb-000009
表6 本申请提供的编码树定义语法之五
Figure PCTCN2020087289-appb-000010
进一步地，MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
对于解码端设备，执行步骤S804后，还可以解析包含当前图像块的码流获取每个CU的解码信息，并根据解码信息对CU解码得到重建块。具体地，解码端设备从当前图像块所在图像的码流中解析每个CU的语法元素，获得每个CU的预测信息和残差信息，根据CU的预测模式对其执行帧间预测处理或帧内预测处理，得到CU的帧间预测图像或帧内预测图像。再根据CU的残差信息，将变换系数经过反量化和反变换处理得到残差图像，并叠加到CU的预测图像上，得到CU的重建块。
通过上述方案，在视频编码过程中，对当前图像块进行划分时，能够将图像块划分为一个或多个满足设定的CU最大宽高比的CU，能够解决现有技术中图像划分过程中，由于设定的CU最大宽高比的限定，出现必须划分但无法划分的图像块的问题，进而可以提高编码性能。
当MaxBTSize和MaxEqtSize设置为小于64时，按照现有的编码树定义语法会导致边界LCU划分得到的N×64或64×N(N<64)的图像无法继续划分，从较大的影响到编码性能。例如MaxBTSize和MaxEqtSize均设置为8时，在边界CTU中划分产生的16x64的块不能继续划分，又如，在边界LCU中通过BT划分产生的64x64的块不能继续划分。为了解决这一问题，参见图10，本申请还提供了另一种图像划分方法，应用于视频编码(包括编码和解码)过程，该方法可由源设备12、目的设备14、视频编码器20视频解码器30、视频译码设备400或者视频译码设备500执行。该方法主要包括以下步骤：
S1001：获取当前图像块的块信息。
其中，当前图像块可以是当前图像划分出的一个图像块，对应于当前图像的编码树上的一个节点，当前图像块也可以是当前图像的一个LCU(例如，在HEVC标准中的CTU)，也可以是以LCU为根节点划分得到的子块，还可以是以某一层级的子块为根节点划分得到的下一层级的子块。
当前图像块的块信息可以包括当前图像块的尺寸信息，例如当前图像块的宽度、当前图像块的高度或者基于当前图像块的宽度和高度得到的面积。当前图像块的块信息还可以包括当前图像块中像素点的坐标，例如当前图像块中像素点在图像坐标系中的坐标，其中，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向(x轴)，图像坐标系的纵轴为当前图像块所在的图像的高度方向(y轴)。进一步地，当前图像的块信息还可以当前图像块对应的其他图像相关信息，例如，当前图像块是否超出当前图像的边界，对于视频解码端设备这些块信息能够从当前图像的码流中解析或者推导得到。
其中，判断当前图像块是否超出当前图像块所在图像的边界的具体方法可以参见步骤S801中的相关描述，此处不再赘述。
S1002：根据获取到的块信息，从候选划分方式集合中确定可用划分方式。其中， 当当前图像块超出当前图像块所在图像的边界时，根据当前图像块的块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断候选划分方式集合中QT划分方式是否为可用划分方式。
其中，候选划分方式集合还可以包括但不限于不划分方式、水平二叉树HBT划分方式，垂直二叉树VBT划分方式，水平扩展四叉树HEQT划分方式，以及垂直扩展四叉树VEQT划分方式中的一种或多种。
当当前图像块超出当前图像块所在图像的边界时，判断QT划分方式是否为可用划分方式的具体方式参见上述第一中图像划分方法中方式A与方式B的相关描述，此处不再赘述。
S1003：从确定出的可用划分方式中，确定当前图像块的划分方式。
其中，从确定出的可用划分方式中，确定当前图像块的划分方式的具体方法可以参见步骤S803中的相关描述，此处不再赘述。
S1004：根据当前图像块的划分方式，从当前图像块得到一个CU或多个CU。
其中，当当前图像块的划分方式为不划分方式时，当前图像块为一个CU；当当前图像块的划分方式为不划分方式外的任一划分方式时，根据当前图像块的划分方式对当前图像块进行划分，若划分得到的子块的至少一个边长为T，T为4或8，则子块为一个CU，否则对该子块重复上述步骤S1002和S1003，继续确定划分方式，将当前图像块递归划分为多个CU。
对于解码端设备，执行步骤S1004后，还可以解析包含当前图像块的码流获取每个CU的解码信息，并根据解码信息对CU解码得到重建块。具体地，解码端设备从当前图像块所在图像的码流中解析每个CU的语法元素，获得每个CU的预测信息和残差信息，根据CU的预测模式对其执行帧间预测处理或帧内预测处理，得到CU的帧间预测图像或帧内预测图像。再根据CU的残差信息，将变换系数经过反量化和反变换处理得到残差图像，并叠加到CU的预测图像上，得到CU的重建块。
通过上述方案，在视频编码过程中，对当前图像块进行划分时，当当前图像块超出图像块所在图像的边界时尽量采用QT划分方式，避免对边界图像块划分得到N×64或64×N(N<64)的图像块，进而避免当MaxBTSize和MaxEqtSize设置为小于64时，N×64或64×N(N<64)的图像块无法继续划分的问题，进而可以提高编码性能。
参阅图11所示，本申请实施例还提供了一种视频编码设备1100，该视频编码设备1100中包括：获取单元1101、确定单元1102和划分单元1103。
在一个可能的实施方式中，视频编码设备1100用于实现如图8所示的图像划分方法，其中，
获取单元1101，用于获取当前图像块的块信息。
确定单元1102，用于根据获取单元1101获取到的块信息，从候选划分方式集合中确定可用划分方式；以及，从确定出的可用划分方式中，确定当前图像块的划分方式。
划分单元1103，用于根据确定单元1102确定的当前图像块的划分方式，从当前图像块得到一个编码单元CU或多个CU；其中，每个CU的宽高比满足设定的CU的最大宽高比。
其中，设定的CU的最大宽高比可以为4或8。
进一步地，候选划分方式集合可以包括不划分方式、水平二叉树HBT划分方式，垂直二叉树VBT划分方式，水平扩展四叉树HEQT划分方式，垂直扩展四叉树VEQT划分方式以及四叉树QT划分方式中的一种或多种。
示例性的，确定单元1102具体用于：根据当前图像块的块信息，判断当前图像块是否满足第一条件；当当前图像块满足所述第一条件时，确定VBT划分方式为可用划分方式。其中，第一条件为width>height*MaxPartRatio，width为当前图像块的宽度，height为当前图像块的高度，MaxPartRatio为设定的CU的最大宽高比。
示例性的，确定单元1102具体用于：根据当前图像块的块信息，判断所述当前图像块是否满足第二条件；当当前图像块满足第二条件，确定HBT划分方式为可用划分方式；其中，第二条件为height>width*MaxPartRatio，width为当前图像块的宽度，height为当前图像块的高度，MaxPartRatio为设定的CU的最大宽高比。
示例性的，确定单元1102具体用于：根据当前图像块的块信息，判断当前图像块是否满足第一条件集合中的条件；当当前图像块满足第一条件集合中的所有条件时，确定VEQT划分方式为可用划分方式。其中，第一条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)height≥MinEqtSize*2；(4)width≥MinEqtSize*4；(5)height*4≤MaxPartRatio*width；(6)height*MaxPartRatio≥width；其中，width为当前图像块的宽度，height为当前图像块的高度，MaxEqtSize为设定的最大EQT的尺寸，MinEqtSize为设定的最小EQT的尺寸，MaxPartRatio为设定的CU的最大宽高比。
示例性的，确定单元1102具体用于：根据当前图像块的块信息，判断当前图像块是否满足第二条件集合中的条件；当当前图像块满足第二条件集合中的所有条件时，确定HEQT划分方式为可用划分方式。其中，第二条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)width≥MinEqtSize*2；(4)height≥MinEqtSize*4；(5)width*4≤MaxPartRatio*height；(7)width*MaxPartRatio≥height；其中，width为当前图像块的宽度，heigh为当前图像块的高度，MaxEqtSize为最大EQT的尺寸，MinEqtSize为最小EQT的尺寸，MaxPartRatio为设定的CU的最大宽高比。
进一步地，确定单元1102还用于：根据当前图像块的块信息，确定当前图像块在所述当前图像块的边界内。
示例性的，确定单元1102具体用于：根据当前图像块的块信息，判断当前图像块是否满足第三条件；当当前图像块满足第三条件时，确定当前图像块在所述当前图像块的边界内。其中，第三条件为：(x0+width)≤PicWidth，且(y0+height)≤PicHeight；所述x0为图像坐标系中当前图像块左上顶点的像素点的横坐标，所述y0为图像坐标系中当前图像块左上顶点的像素点的纵坐标，图像坐标系的原点为当前图像块所在的图像的左上第顶点的像素点，图像坐标系的横轴为当前图像块所在的图像的宽度方向，所述图像坐标系的纵轴为当前图像块所在的图像的高度方向；PicWidth为当前图像块所在的图像的宽度，PicHeight为当前图像块所在的图像的高度。
进一步地，确定单元1102还用于：根据当前图像块的块信息确定当前图像块超出当前图像块所在图像的边界；根据块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断QT划分方式是否为可用划分方式。
示例性的，确定单元1102具体用于：根据当前图像块的块信息，判断当前图像块是否 满足第三条件集合中的条件；若当前图像块满足第三条件集合中的至少一个条件，则确定QT划分方式为可用划分方式。
其中，第三条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和所述MaxEqtSize中的最大值。
示例性的，确定单元1102具体用于：根据前图像块的块信息，判断当前图像块是否满足第四条件集合中的条件；若当前图像块满足第四条件集合中的至少一个条件，则确定QT划分方式为可用划分方式。
其中，第四条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)当前图像块未超出图像块所在图像的右边界，且未超出图像块所在图像的下边界；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
示例性的，MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
示例性的，确定单元1102具体用于：当可用划分方式为一种时，将该可用划分方式确定为当前图像块的划分方式。
示例性的，确定单元1102具体用于：当可用划分方式为多种时，根据确定出的可用划分方式，解析包括当前图像块的码流，并根据解析结果确定当前图像块的划分方式。
示例性的，确定单元1102具体用于：当可用划分方式为多种时，分别确定每个可用划分方式的率失真代价，将可用划分方式中率失真代价最小的可用划分方式，确定为当前图像块的划分方式。
在另一个可能的实施方式中，视频编码设备1100用于实现如图9所示的图像划分方法，其中，
获取单元1101，用于获取当前图像块的块信息。
确定单元1102，用于根据获取单元1101获取到的块信息，从候选划分方式集合中确定可用划分方式；其中，候选划分方式集合中包括四叉树QT划分方式，当当前图像块超出当前图像块所在图像的边界时，根据块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断QT划分方式是否为可用划分方式；以及，从确定出的可用划分方式中，确定所述当前图像块的划分方式。
划分单元1103，用于根据当前图像块的划分方式，从当前图像块得到一个编码单元CU或多个CU。
示例性的，确定单元1102具体用于：根据当前图像块的块信息，判断当前图像块是否满足第一条件集合中的条件；若当前图像块满足第一条件集合中的至少一个条件，则确定QT划分方式为可用划分方式。
其中，第一条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和所述MaxEqtSize中的最大值。
示例性的，确定单元1102具体用于：根据前图像块的块信息，判断当前图像块是否满足第二条件集合中的条件；若当前图像块满足第二条件集合中的至少一个条件，则确定QT划分方式为可用划分方式。
其中，第二条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)当前图像块未超出图像块所在图像的右边界，且未超出图像块所在图像的下边界；width为当前图像块的宽度，heigh为当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
示例性的，MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
示例性的，确定单元1102具体用于：当可用划分方式为一种时，将该可用划分方式确定为当前图像块的划分方式。
示例性的，确定单元1102具体用于：当可用划分方式为多种时，根据确定出的可用划分方式，解析包括当前图像块的码流，并根据解析结果确定当前图像块的划分方式。
示例性的，确定单元1102具体用于：当可用划分方式为多种时，分别确定每个可用划分方式的率失真代价，将可用划分方式中率失真代价最小的可用划分方式，确定为当前图像块的划分方式。
需要说明的是，本申请实施例提供的图像划分装置中的各个单元为实现本申请图像划分方法中所包含的各种执行步骤的功能主体，即具备实现完整实现本申请提供的图像划分方法中的各个步骤以及这些步骤的扩展及变形的功能主体，具体请参见本文中对图像划分方法的介绍，为简洁起见，此处不再赘述。
本申请实施例中对单元的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可 以有另外的划分方式。在本申请的实施例中的各功能模块可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。所述集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)或处理器(processor)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：移动硬盘、ROM、RAM、磁碟或者光盘等各种可以存储程序代码的介质。
参见图12所示，本申请实施例还提供了一种视频编码设备1200，视频编码设备1200包括：存储器1201和处理器1202，存储器1201和处理器1202相互连接。
在一个可能的实施方式中，处理器1202用于调用存储在存储器1201中的程序代码执行本申请提供的第一种图像划分方法中任意一种可能的实施方式。
在另一个可能的实施方式中，处理器1202用于调用存储在存储器1201中的程序代码执行本申请提供的第二种图像划分方法中任意一种可能的实施方式。
本领域技术人员能够领会，结合本文公开描述的各种说明性逻辑框、模块和算法步骤所描述的功能可以硬件、软件、固件或其任何组合来实施。如果以软件来实施，那么各种说明性逻辑框、模块、和步骤描述的功能可作为一或多个指令或代码在计算机可读媒体上存储或传输，且由基于硬件的处理单元执行。计算机可读媒体可包含计算机可读存储媒体，其对应于有形媒体，例如数据存储媒体，或包括任何促进将计算机程序从一处传送到另一处的媒体(例如，根据通信协议)的通信媒体。以此方式，计算机可读媒体大体上可对应于(1)非暂时性的有形计算机可读存储媒体，或(2)通信媒体，例如信号或载波。数据存储媒体可为可由一或多个计算机或一或多个处理器存取以检索用于实施本申请中描述的技术的指令、代码和/或数据结构的任何可用媒体。计算机程序产品可包含计算机可读媒体。
作为实例而非限制，此类计算机可读存储媒体可包括RAM、ROM、EEPROM、CD-ROM或其它光盘存储装置、磁盘存储装置或其它磁性存储装置、快闪存储器或可用来存储指令或数据结构的形式的所要程序代码并且可由计算机存取的任何其它媒体。并且，任何连接被恰当地称作计算机可读媒体。举例来说，如果使用同轴缆线、光纤缆线、双绞线、数字订户线(DSL)或例如红外线、无线电和微波等无线技术从网站、服务器或其它远程源传输指令，那么同轴缆线、光纤缆线、双绞线、DSL或例如红外线、无线电和微波等无线技术包含在媒体的定义中。但是，应理解，所述计算机可读存储媒体和数据存储媒体并不包括连接、载波、信号或其它暂时媒体，而是实际上针对于非暂时性有形存储媒体。如本文中所使用，磁盘和光盘包含压缩光盘(CD)、激光光盘、光学光盘、数字多功能光盘(DVD)和蓝光光盘，其中磁盘通常以磁性方式再现数据，而光盘利用激光以光学方式再现数据。以上各项的组合也应包含在计算机可读媒体的范围内。
可通过例如一或多个数字信号处理器(DSP)、通用微处理器、专用集成电路(ASIC)、现场可编程逻辑阵列(FPGA)或其它等效集成或离散逻辑电路等一或多个处理器来执行指令。因此，如本文中所使用的术语“处理器”可指前述结构或适合于实施本文中所描述的技术的任一其它结构中的任一者。另外，在一些方面中，本文中所描述的各种说明性逻辑框、 模块、和步骤所描述的功能可以提供于经配置以用于编码和解码的专用硬件和/或软件模块内，或者并入在组合编解码器中。而且，所述技术可完全实施于一或多个电路或逻辑元件中。
本申请的技术可在各种各样的装置或设备中实施，包含无线手持机、集成电路(IC)或一组IC(例如，芯片组)。本申请中描述各种组件、模块或单元是为了强调用于执行所揭示的技术的装置的功能方面，但未必需要由不同硬件单元实现。实际上，如上文所描述，各种单元可结合合适的软件和/或固件组合在编码解码器硬件单元中，或者通过互操作硬件单元(包含如上文所描述的一或多个处理器)来提供。
在上述实施例中，对各个实施例的描述各有侧重，某个实施例中没有详述的部分，可以参见其他实施例的相关描述。
以上所述，仅为本申请示例性的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应该以权利要求的保护范围为准。

Claims (48)

  1. 一种图像划分方法，应用于视频编码过程，其特征在于，包括：
    获取当前图像块的块信息；
    根据所述块信息，从候选划分方式集合中确定可用划分方式；
    从确定出的可用划分方式中，确定所述当前图像块的划分方式；
    根据所述当前图像块的划分方式，从所述当前图像块得到一个编码单元CU或多个CU；其中，所述CU的宽高比满足设定的CU的最大宽高比。
  2. 如权利要求1所述的方法，其特征在于，所述设定的CU的最大宽高比为4或8。
  3. 如权利要求1或2所述的方法，其特征在于，所述候选划分方式集合包括不划分方式、水平二叉树HBT划分方式，垂直二叉树VBT划分方式，水平扩展四叉树HEQT划分方式，垂直扩展四叉树VEQT划分方式以及四叉树QT划分方式中的一种或多种。
  4. 如权利要求3所述的方法，其特征在于，根据所述块信息，从候选划分方式集合中确定可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第一条件；
    当所述当前图像块满足所述第一条件时，确定所述VBT划分方式为可用划分方式；
    其中，所述第一条件为width>height*MaxPartRatio，width为所述当前图像块的宽度，height为所述当前图像块的高度，MaxPartRatio为所述设定的CU的最大宽高比。
  5. 如权利要求3或4所述的方法，其特征在于，根据所述块信息，从候选划分方式集合中确定可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第二条件；
    当所述当前图像块满足所述第二条件，确定所述HBT划分方式为可用划分方式；
    其中，所述第二条件为height>width*MaxPartRatio，width为所述当前图像块的宽度，height为所述当前图像块的高度，MaxPartRatio为所述设定的CU的最大宽高比。
  6. 如权利要求3-5任意一项所述的方法，其特征在于，根据所述块信息，从候选划分方式集合中确定可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第一条件集合中的条件；
    当所述当前图像块满足所述第一条件集合中的所有条件时，确定所述VEQT划分方式为可用划分方式；
    其中，所述第一条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)height≥MinEqtSize*2；(4)width≥MinEqtSize*4；(5)height*4≤MaxPartRatio*width；(6)height*MaxPartRatio≥width；其中，width为所述当前图像块的宽度，height为所述当前图像块的高度，MaxEqtSize为设定的最大EQT的尺寸，MinEqtSize为设定的最小EQT的尺寸，MaxPartRatio为所述设定的CU的最大宽高比。
  7. 如权利要求3-6任意一项所述的方法，其特征在于，根据所述块信息，从候选划分方式集合中确定可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第二条件集合中的条件；
    当所述当前图像块满足所述第二条件集合中的所有条件时，确定所述HEQT划分方式为可用划分方式；
    其中，所述第二条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)width≥MinEqtSize*2；(4)height≥MinEqtSize*4；(5)width*4≤MaxPartRatio*height；(7)width*MaxPartRatio≥height；其中，width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxEqtSize为最大EQT的尺寸，MinEqtSize为最小EQT的尺寸，MaxPartRatio为所述CU的最大宽高比。
  8. 如权利要求4至7任意一项所述的方法，其特征在于，所述方法还包括：根据所述块信息，确定所述当前图像块在所述当前图像块所在的图像的边界内。
  9. 如权利要求8任意一项所述的方法，其特征在于，根据所述块信息，确定所述当前图像块在所述当前图像块所在的图像的边界内，包括：
    根据所述块信息，判断所述当前图像块是否满足第三条件；
    当所述当前图像块满足所述第三条件时，确定所述当前图像块在所述当前图像块的边界内；
    其中，所述第三条件为：(x0+width)≤PicWidth，且(y0+height)≤PicHeight；所述x0为图像坐标系中所述当前图像块左上顶点的像素点的横坐标，所述y0为所述图像坐标系中所述当前图像块左上顶点的像素点的纵坐标，所述图像坐标系的原点为所述当前图像块所在的图像的左上第顶点的像素点，所述图像坐标系的横轴为所述当前图像块所在的图像的宽度方向，所述图像坐标系的纵轴为所述当前图像块所在的图像的高度方向；PicWidth为所述当前图像块所在的图像的宽度，PicHeight为所述当前图像块所在的图像的高度。
  10. 如权利要求3-9任意一项所述的方法，其特征在于，还包括：
    根据所述块信息确定所述当前图像块超出所述当前图像块所在图像的边界；以及
    根据所述块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式。
  11. 如权利要求10所述的方法，其特征在于，根据所述块信息、最大BT的尺寸以及最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第三条件集合中的条件；
    若所述当前图像块满足所述第三条件集合中的至少一个条件，则确定所述QT划分方式为可用划分方式；
    其中，所述第三条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为所述MaxBTSize和所述MaxEqtSize中的最大值。
  12. 如权利要求10所述的方法，其特征在于，根据所述块信息、最大BT的尺寸以及最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第四条件集合中的条件；
    若所述当前图像块满足所述第四条件集合中的至少一个条件，则确定所述QT划分方式为可用划分方式；
    其中，所述第四条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)所述当前图像块未超出所述图像块所在图像的右边界，且未超出所述图像块所在图像的下边界；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
  13. 如权利要求6、7、11或12所述的方法，其特征在于，所述MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
  14. 如权利要求1-13任意一项所述的方法，其特征在于，从确定出的可用划分方式中，确定所述当前图像块的划分方式，包括：
    当所述可用划分方式为一种时，将所述可用划分方式确定为所述当前图像块的划分方式。
  15. 如权利要求1-13任意一项所述的方法，其特征在于，从确定出的可用划分方式中，确定所述当前图像块的划分方式，包括：
    当所述可用划分方式为多种时，根据确定出的可用划分方式，解析包括所述当前图像块的码流，并根据解析结果确定所述当前图像块的划分方式。
  16. 如权利要求1-13任意一项所述的方法，其特征在于，从确定出的可用划分方式中，确定所述当前图像块的划分方式，包括：
    当所述可用划分方式为多种时，分别确定所述可用划分方式的率失真代价，将所述可用划分方式中率失真代价最小的可用划分方式，确定为所述当前图像块的划分方式。
  17. 一种图像划分方法，应用于视频编码过程，其特征在于，包括：
    获取当前图像块的块信息；
    根据所述块信息，从候选划分方式集合中确定可用划分方式；其中，所述候选划分方式集合中包括四叉树QT划分方式；当所述当前图像块超出所述当前图像块所在图像的边界时，根据所述块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式；
    从确定出的可用划分方式中，确定所述当前图像块的划分方式；
    根据所述当前图像块的划分方式，从所述当前图像块得到一个编码单元CU或多个CU。
  18. 如权利要求17所述的方法，其特征在于，根据所述块信息、最大BT的尺寸以及最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第一条件集合中的条件；
    若所述当前图像块满足所述第一条件集合中的至少一个条件，则确定所述QT划分方式为可用划分方式；
    其中，所述第一条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为所述MaxBTSize和所述MaxEqtSize中的最大值。
  19. 如权利要求17所述的方法，其特征在于，根据所述块信息、最大BT的尺寸以及最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第二条件集合中的条件；
    若所述当前图像块满足所述第二条件集合中的至少一个条件，则确定所述QT划分方式为可用划分方式；
    其中，所述第二条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)所述当前图像块未超出所述图像块所在图像的右边界，且未超出所述图像块所在图像的下边界；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
  20. 如权利要求18或19所述的方法，其特征在于，所述MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
  21. 如权利要求17-20任意一项所述的方法，其特征在于，从确定出的可用划分方式中，确定所述当前图像块的划分方式，包括：
    当所述可用划分方式为一种时，将所述可用划分方式确定为所述当前图像块的划分方式。
  22. 如权利要求17-20任意一项所述的方法，其特征在于，从确定出的可用划分方式中，确定所述当前图像块的划分方式，包括：
    当所述可用划分方式为多种时，根据确定出的可用划分方式，解析包括所述当前图像块的码流，并根据解析结果确定所述当前图像块的划分方式。
  23. 如权利要求17-22任意一项所述的方法，其特征在于，从确定出的可用划分 方式中，确定所述当前图像块的划分方式，包括：
    当所述可用划分方式为多种时，分别确定所述可用划分方式的率失真代价，将所述可用划分方式中率失真代价最小的可用划分方式，确定为所述当前图像块的划分方式。
  24. 一种图像划分装置，应用于视频编码，其特征在于，包括：
    获取单元，用于获取当前图像块的块信息；
    确定单元，用于根据所述块信息，从候选划分方式集合中确定可用划分方式；以及，从确定出的可用划分方式中，确定所述当前图像块的划分方式；
    划分单元，用于根据所述当前图像块的划分方式，从所述当前图像块得到一个编码单元CU或多个CU；其中，所述CU的宽高比满足设定的CU的最大宽高比。
  25. 如权利要求24所述的装置，其特征在于，所述设定的CU的最大宽高比为4或8。
  26. 如权利要求24或25所述的装置，其特征在于，所述候选划分方式集合包括不划分方式、水平二叉树HBT划分方式，垂直二叉树VBT划分方式，水平扩展四叉树HEQT划分方式，垂直扩展四叉树VEQT划分方式以及四叉树QT划分方式中的一种或多种。
  27. 如权利要求26所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第一条件；
    当所述当前图像块满足所述第一条件时，确定所述VBT划分方式为可用划分方式；
    其中，所述第一条件为width>height*MaxPartRatio，width为所述当前图像块的宽度，height为所述当前图像块的高度，MaxPartRatio为所述设定的CU的最大宽高比。
  28. 如权利要求26或27所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第二条件；
    当所述当前图像块满足所述第二条件，确定所述HBT划分方式为可用划分方式；
    其中，所述第二条件为height>width*MaxPartRatio，width为所述当前图像块的宽度，height为所述当前图像块的高度，MaxPartRatio为所述设定的CU的最大宽高比。
  29. 如权利要求26-28任意一项所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第一条件集合中的条件；
    当所述当前图像块满足所述第一条件集合中的所有条件时，确定所述VEQT划分方式为可用划分方式；
    其中，所述第一条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)height≥MinEqtSize*2；(4)width≥MinEqtSize*4；(5)height*4≤MaxPartRatio*width；(6)height*MaxPartRatio≥width；其中，width为所述当前图像块的宽度，height为所述当前图像块的高度，MaxEqtSize为设定的最大EQT的尺寸，MinEqtSize为设定的最小EQT的尺寸，MaxPartRatio为所述设定的CU的最大宽高比。
  30. 如权利要求26-29任意一项所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第二条件集合中的条件；
    当所述当前图像块满足所述第二条件集合中的所有条件时，确定所述HEQT划分 方式为可用划分方式；
    其中，所述第二条件集合包括以下条件：(1)width≤MaxEqtSize；(2)height≤MaxEqtSize；(3)width≥MinEqtSize*2；(4)height≥MinEqtSize*4；(5)width*4≤MaxPartRatio*height；(7)width*MaxPartRatio≥height；其中，width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxEqtSize为最大EQT的尺寸，MinEqtSize为最小EQT的尺寸，MaxPartRatio为所述CU的最大宽高比。
  31. 如权利要求27-30任意一项所述的装置，其特征在于，所述确定单元还用于：根据所述块信息，确定所述当前图像块在所述当前图像块的边界内。
  32. 如权利要求31所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第三条件；
    当所述当前图像块满足所述第三条件时，确定所述当前图像块在所述当前图像块的边界内；
    其中，所述第三条件为：(x0+width)≤PicWidth，且(y0+height)≤PicHeight；所述x0为图像坐标系中所述当前图像块左上顶点的像素点的横坐标，所述y0为所述图像坐标系中所述当前图像块左上顶点的像素点的纵坐标，所述图像坐标系的原点为所述当前图像块所在的图像的左上第顶点的像素点，所述图像坐标系的横轴为所述当前图像块所在的图像的宽度方向，所述图像坐标系的纵轴为所述当前图像块所在的图像的高度方向；PicWidth为所述当前图像块所在的图像的宽度，PicHeight为所述当前图像块所在的图像的高度。
  33. 如权利要求26-32任意一项所述的装置，其特征在于，所述确定单元还用于：
    根据所述块信息，确定所述当前图像块超出所述当前图像块所在图像的边界；
    根据所述块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式。
  34. 如权利要求33所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第三条件集合中的条件；
    若所述当前图像块满足所述第三条件集合中的至少一个条件，则确定所述QT划分方式为可用划分方式；
    其中，所述第三条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为所述MaxBTSize和所述MaxEqtSize中的最大值。
  35. 如权利要求33所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第四条件集合中的条件；
    若所述当前图像块满足所述第四条件集合中的至少一个条件，则确定所述QT划 分方式为可用划分方式；
    其中，所述第四条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)所述当前图像块未超出所述图像块所在图像的右边界，且未超出所述图像块所在图像的下边界；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
  36. 如权利要求29、30、34或35所述的装置，其特征在于，所述MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
  37. 如权利要求24-36任意一项所述的装置，其特征在于，所述确定单元具体用于：
    当所述可用划分方式为一种时，将所述可用划分方式确定为所述当前图像块的划分方式。
  38. 如权利要求24-36任意一项所述的装置，其特征在于，所述确定单元具体用于：
    当所述可用划分方式为多种时，根据确定出的可用划分方式，解析包括所述当前图像块的码流，并根据解析结果确定所述当前图像块的划分方式。
  39. 如权利要求24-36任意一项所述的装置，其特征在于，所述确定单元具体用于：
    当所述可用划分方式为多种时，分别确定所述可用划分方式的率失真代价，将所述可用划分方式中率失真代价最小的可用划分方式，确定为所述当前图像块的划分方式。
  40. 一种图像划分装置，应用于视频编码过程，其特征在于，包括：
    获取单元，用于获取当前图像块的块信息；
    确定单元，用于根据所述块信息，从候选划分方式集合中确定可用划分方式，其中，所述候选划分方式集合中包括四叉树QT划分方式，当所述当前图像块超出所述当前图像块所在图像的边界时，根据所述块信息、设定的最大BT的尺寸以及设定的最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式；以及，从确定出的可用划分方式中，确定所述当前图像块的划分方式；
    划分单元，用于根据所述当前图像块的划分方式，从所述当前图像块得到一个编码单元CU或多个CU。
  41. 如权利要求40所述的装置，其特征在于，所述确定单元具体用于：
    根据所述块信息，判断所述当前图像块是否满足第一条件集合中的条件；
    若所述当前图像块满足所述第一条件集合中的至少一个条件，则确定所述QT划分方式为可用划分方式；
    其中，所述第一条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为设定的最大BT的尺寸，MaxEqtSize为设定的最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为所述MaxBTSize和所述MaxEqtSize中的最大值。
  42. 如权利要求40所述的装置，其特征在于，根据所述块信息、最大BT的尺寸以及最大EQT的尺寸，判断所述QT划分方式是否为可用划分方式，包括：
    根据所述块信息，判断所述当前图像块是否满足第二条件集合中的条件；
    若所述当前图像块满足所述第二条件集合中的至少一个条件，则确定所述QT划分方式为可用划分方式；
    其中，所述第二条件集合包括以下条件中的一个或多个：(1)width＞MaxBTSize，且width＞MaxEqtSize；(2)height＞MaxBTSize，且height＞MaxEqtSize；(3)width＞MaxBTSize，width＞MaxEqtSize，height＞MaxBTSize，且height＞MaxEqtSize；(4)width＞max(MaxBTSize，MaxEqtSize)；(5)height＞max(MaxBTSize，MaxEqtSize)；(6)width＞max(MaxBTSize，MaxEqtSize)，且height＞max(MaxBTSize，MaxEqtSize)；(7)width＞MaxBTSize；(8)height＞MaxBTSize；(9)width＞MaxEqtSize；(10)height＞MaxEqtSize；(11)所述当前图像块未超出所述图像块所在图像的右边界，且未超出所述图像块所在图像的下边界；
    width为所述当前图像块的宽度，heigh为所述当前图像块的高度，MaxBTSize为最大BT的尺寸，MaxEqtSize为最大EQT的尺寸，max(MaxBTSize，MaxEqtSize)为MaxBTSize和MaxEqtSize中的最大值。
  43. 如权利要求41或42所述的装置，其特征在于，所述MaxEqtSize为2 M，其中，M的取值为3、4、5或6。
  44. 如权利要求40-43任意一项所述的装置，其特征在于，所述确定单元具体用于：
    当所述可用划分方式为一种时，将所述可用划分方式确定为所述当前图像块的划分方式。
  45. 如权利要求40-43任意一项所述的装置，其特征在于，所述确定单元具体用于：
    当所述可用划分方式为多种时，根据确定出的可用划分方式，解析包括所述当前图像块的码流，并根据解析结果确定所述当前图像块的划分方式。
  46. 如权利要求40-43任意一项所述的装置，其特征在于，所述确定单元具体用于：
    当所述可用划分方式为多种时，分别确定所述可用划分方式的率失真代价，将所述可用划分方式中率失真代价最小的可用划分方式，确定为所述当前图像块的划分方 式。
  47. 一种视频编码设备，其特征在于，包括：相互耦合的存储器和处理器；
    所述处理器调用存储在所述存储器中的程序代码执行如权利要求1-16中任意一项所描述的方法。
  48. 一种视频编码设备，其特征在于，包括：相互耦合的存储器和处理器；
    所述处理器调用存储在所述存储器中的程序代码执行如权利要求17-23中任意一项所描述的方法。
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