WO2020184555A1 - 符号化装置、復号装置、符号化方法及び復号方法 - Google Patents
符号化装置、復号装置、符号化方法及び復号方法 Download PDFInfo
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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
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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
- H04N19/103—Selection of coding mode or of prediction mode
- H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
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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
- H04N19/103—Selection of coding mode or of prediction mode
- H04N19/109—Selection of coding mode or of prediction mode among a plurality of temporal predictive coding modes
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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
- H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
- H04N19/122—Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
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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
- H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
- H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
- H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
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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
- H04N19/169—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
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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
- H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
- H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
- H04N19/51—Motion estimation or motion compensation
- H04N19/513—Processing of motion vectors
- H04N19/517—Processing of motion vectors by encoding
- H04N19/52—Processing of motion vectors by encoding by predictive encoding
Definitions
- the present disclosure relates to video coding, for example, systems, components, and methods in video coding and decoding.
- Video coding technology is based on H.264. From 261 and MPEG-1, H.M. 264 / AVC (Advanced Video Coding), MPEG-LA, H. H.265/HEVC (High Efficiency Video Coding), and H.264. We are making progress toward 266 / VVC (Versatile Video Codec). With this advancement, there is a constant need to provide improvements and optimizations in video coding techniques to handle the ever-growing amount of digital video data in a variety of applications.
- Non-Patent Document 1 relates to an example of a conventional standard relating to the above-mentioned video coding technology.
- the present disclosure may contribute to one or more of, for example, improvement of coding efficiency, improvement of image quality, reduction of processing amount, reduction of circuit scale, improvement of processing speed, and appropriate selection of elements or operations.
- a configuration or method is provided. It should be noted that the present disclosure may include configurations or methods that can contribute to benefits other than the above.
- the coding apparatus includes a circuit and a memory connected to the circuit, and the circuit uses a first motion vector to obtain a predicted image of a block to be processed in operation.
- HMVP First In First Out
- FIFO Threshold In First Out
- the history based motion vector (predictor) table is updated, and in the update of the HMVP table, it is determined whether or not the size of the processing target block is equal to or less than the threshold size, and the size of the processing target block is equal to or less than the threshold size. If it is determined, the update of the HMVP table is skipped.
- Some implementations of the embodiments in the present disclosure may improve coding efficiency, simplify coding / decoding processing, or increase coding / decoding processing speed.
- Appropriate filters, block sizes, motion vectors, reference pictures, reference blocks, etc. may be used to efficiently select appropriate components / actions used for encoding and decoding.
- the configuration or method according to one aspect of the present disclosure includes, for example, improvement of coding efficiency, improvement of image quality, reduction of processing amount, reduction of circuit scale, improvement of processing speed, and appropriate selection of elements or operations. Can contribute to more than one of them. Note that the configuration or method according to one aspect of the present disclosure may contribute to benefits other than the above.
- FIG. 1 is a block diagram showing a functional configuration of an encoding device according to an embodiment.
- FIG. 2 is a flowchart showing an example of an overall coding process by the coding apparatus.
- FIG. 3 is a conceptual diagram showing an example of block division.
- FIG. 4A is a conceptual diagram showing an example of a slice configuration.
- FIG. 4B is a conceptual diagram showing an example of a tile configuration.
- FIG. 5A is a table showing transformation basis functions corresponding to various transformation types.
- FIG. 5B is a conceptual diagram showing an example of SVT (Spatially Varying Transfer).
- FIG. 6A is a conceptual diagram showing an example of the shape of the filter used in ALF (adaptive loop filter).
- FIG. 6B is a conceptual diagram showing another example of the shape of the filter used in ALF.
- FIG. 6C is a conceptual diagram showing another example of the shape of the filter used in ALF.
- FIG. 7 is a block diagram showing an example of a detailed configuration of a loop filter unit that functions as a DBF (deblocking filter).
- FIG. 8 is a conceptual diagram showing an example of a deblocking filter having a filter characteristic symmetrical with respect to a block boundary.
- FIG. 9 is a conceptual diagram for explaining a block boundary on which deblocking filtering is performed.
- FIG. 10 is a conceptual diagram showing an example of the Bs value.
- FIG. 11 is a flowchart showing an example of processing performed by the prediction processing unit of the encoding device.
- FIG. 12 is a flowchart showing another example of the processing performed by the prediction processing unit of the encoding device.
- FIG. 11 is a flowchart showing an example of processing performed by the prediction processing unit of the encoding device.
- FIG. 13 is a flowchart showing another example of the processing performed by the prediction processing unit of the coding apparatus.
- FIG. 14 is a conceptual diagram showing an example of 67 intra prediction modes in the intra prediction of the embodiment.
- FIG. 15 is a flowchart showing an example of the basic processing flow of inter prediction.
- FIG. 16 is a flowchart showing an example of motion vector derivation.
- FIG. 17 is a flowchart showing another example of deriving the motion vector.
- FIG. 18 is a flowchart showing another example of deriving the motion vector.
- FIG. 19 is a flowchart showing an example of inter-prediction by the normal inter-mode.
- FIG. 20 is a flowchart showing an example of inter-prediction by the merge mode.
- FIG. 21 is a conceptual diagram for explaining an example of motion vector derivation processing in the merge mode.
- FIG. 22 is a flowchart showing an example of FRUC (frame rate up conversion) processing.
- FIG. 23 is a conceptual diagram for explaining an example of pattern matching (bilateral matching) between two blocks along a motion trajectory.
- FIG. 24 is a conceptual diagram for explaining an example of pattern matching (template matching) between a template in the current picture and a block in the reference picture.
- FIG. 25A is a conceptual diagram for explaining an example of deriving a motion vector in sub-block units based on motion vectors of a plurality of adjacent blocks.
- FIG. 25B is a conceptual diagram for explaining an example of derivation of a motion vector in subblock units in an affine mode having three control points.
- FIG. 26A is a conceptual diagram for explaining the affine merge mode.
- FIG. 26B is a conceptual diagram for explaining the affine merge mode having two control points.
- FIG. 26C is a conceptual diagram for explaining an affine merge mode having three control points.
- FIG. 27 is a flowchart showing an example of processing in the affine merge mode.
- FIG. 28A is a conceptual diagram for explaining an affine intermode having two control points.
- FIG. 28B is a conceptual diagram for explaining an affine inter mode having three control points.
- FIG. 29 is a flowchart showing an example of processing in the affine intermode.
- FIG. 30A is a conceptual diagram for explaining an affine intermode in which the current block has three control points and the adjacent block has two control points.
- FIG. 30A is a conceptual diagram for explaining an affine intermode in which the current block has three control points and the adjacent block has two control points.
- FIG. 30B is a conceptual diagram for explaining an affine intermode in which the current block has two control points and the adjacent block has three control points.
- FIG. 31A is a flowchart showing a merge mode including DMVR (decoder motion vector refinement).
- FIG. 31B is a conceptual diagram for explaining an example of DMVR processing.
- FIG. 32 is a flowchart showing an example of generating a predicted image.
- FIG. 33 is a flowchart showing another example of generation of a predicted image.
- FIG. 34 is a flowchart showing another example of generation of a predicted image.
- FIG. 35 is a flowchart for explaining an example of the prediction image correction process by the OBMC (overlapped block motion compression) process.
- FIG. 36 is a conceptual diagram for explaining an example of a predicted image correction process by the OBMC process.
- FIG. 37 is a conceptual diagram for explaining the generation of predicted images of two triangles.
- FIG. 38 is a conceptual diagram for explaining a model assuming constant velocity linear motion.
- FIG. 39 is a conceptual diagram for explaining an example of a predicted image generation method using the luminance correction process by the LIC (local illumination compression) process.
- FIG. 40 is a block diagram showing an implementation example of the encoding device.
- FIG. 41 is a block diagram showing a functional configuration of the decoding device according to the embodiment.
- FIG. 42 is a flowchart showing an example of an overall decoding process by the decoding device.
- FIG. 43 is a flowchart showing an example of processing performed by the prediction processing unit of the decoding device.
- FIG. 44 is a flowchart showing another example of the processing performed by the prediction processing unit of the decoding device.
- FIG. 45 is a flowchart showing an example of inter prediction in the normal inter mode in the decoding device.
- FIG. 46 is a block diagram showing an implementation example of the decoding device.
- FIG. 47 is a diagram for explaining an IBC (intra block copy) mode.
- FIG. 48 is a diagram for explaining the HMVP (History based Motion Vector Predictor) mode.
- FIG. 49 is a flowchart showing an example of the operation performed by the coding device and the decoding device according to the first aspect of the present disclosure.
- FIG. 50 is a flowchart showing an example of a process of generating an AMVP candidate list using the HMVP table.
- FIG. 50 is a flowchart showing an example of a process of generating an AMVP candidate list using the HMVP table.
- FIG. 51 is a flowchart showing another example of the process of generating the AMVP candidate list using the HMVP table.
- FIG. 52 is a flowchart showing an example of a process of generating an AMVP candidate list without using the HMVP table.
- FIG. 53 is a flowchart showing another example of the process of generating the AMVP candidate list without using the HMVP table.
- FIG. 54 is a flowchart showing an example of the operation performed by the coding device and the decoding device in the second aspect of the present disclosure.
- FIG. 55 is a flowchart showing the operation performed by the coding apparatus.
- FIG. 56 is a flowchart showing the operation performed by the decoding device.
- FIG. 57 is a block diagram showing an overall configuration of a content supply system that realizes a content distribution service.
- FIG. 58 is a conceptual diagram showing an example of a coding structure at the time of scalable coding.
- FIG. 59 is a conceptual diagram showing an example of a coding structure at the time of scalable coding.
- FIG. 60 is a conceptual diagram showing an example of a display screen of a web page.
- FIG. 61 is a conceptual diagram showing an example of a display screen of a web page.
- FIG. 62 is a block diagram showing an example of a smartphone.
- FIG. 63 is a block diagram showing a configuration example of a smartphone.
- the coding apparatus includes a circuit and a memory connected to the circuit, and the circuit generates a predicted image of a block to be processed by using a first motion vector in operation.
- HMVP Threshold based
- FIFO Threshold In First Out
- Motion Vector Predictor Motion Vector Predictor
- the coding device updates the HMVP table when the size of the block to be processed is larger than the threshold size, so that the processing amount is reduced. Therefore, the coding apparatus has improved coding efficiency.
- the circuit further generates a candidate MVP (Motion Vector Prediction) list including a plurality of predicted motion vector candidates, and selects one of the plurality of predicted motion vector candidates included in the generated candidate MVP list.
- a candidate MVP Motion Vector Prediction
- the use of the HMVP table is prohibited and the size of the processing target block is changed. If it is larger than the threshold size, the use of the HMVP table may be permitted.
- the encoding device generates a candidate MVP list without using the HMVP table when the size of the block to be processed is equal to or less than the threshold value, so that the processing amount is reduced. Therefore, the coding apparatus has improved coding efficiency.
- the size of the processing target block may be defined by the number of pixels in the processing target block.
- the threshold size may be 16 pixels.
- the coding apparatus skips the update of the HMVP table or generates the candidate MVP list without using the HVMP table, so that the processing amount is large. It will be reduced. Therefore, the coding apparatus has improved coding efficiency.
- the size of the processing target block may be defined by the width or height of the processing target block.
- the encoding device skips updating the HMVP table or does not use the HMVP table when, for example, the width or height of the size of the block to be processed is equal to or less than the threshold size (for example, 4 pixels or less). Since the candidate MVP list is generated in the above, the processing amount is reduced. Therefore, the coding apparatus has improved coding efficiency.
- the circuit may use an intermode that refers to a coded picture different from the picture to which the processing target block belongs in generating the predicted image of the processing target block.
- the coding apparatus has a plurality of predicted motion vector candidates (so-called, so-called) for the processing target block based on information such as a plurality of encoded blocks located around the processing target block temporally or spatially.
- Candidate MVP can be acquired and the prediction processing of the processing target block can be performed.
- the circuit may use an IBC (Intra Block Copy) mode that refers to an encoded region of a picture to which the processing target block belongs in generating a predicted image of the processing target block.
- IBC Intelligent Block Copy
- the encoding device can specify and read the reference block based on the motion vector indicating the already encoded and decoded reference block in the same picture as the processing target block.
- the first candidate has first reference picture information corresponding to the first motion vector
- each of the plurality of second candidates has second reference picture information corresponding to the second motion vector.
- the circuit determines whether or not the first candidate matches any of the plurality of second candidates, and the first candidate is any of the plurality of second candidates. If they do not match, the HMVP table may be updated by storing the first candidate in the HMVP table.
- the encoding device expands the range of variations of the first candidate stored in the HMVP table, so that more appropriate prediction candidates for the processing target block can be registered in the candidate MVP list.
- the candidate MVP list may be a candidate MVP list in the AMVP (Adaptive Motion Vector Prediction) mode.
- AMVP Adaptive Motion Vector Prediction
- the coding device can register the predicted motion vector candidate (so-called candidate MVP) in the HMVP mode in the candidate MVP list in the AMVP mode, so that the prediction accuracy is improved.
- candidate MVP predicted motion vector candidate
- the candidate MVP list may be a candidate MVP list in the merge mode.
- the encoding device can register the candidate MVP of the HMVP mode in the candidate MVP list in the merge mode, so that the prediction accuracy is improved.
- the decoding device includes a circuit and a memory connected to the circuit, and the circuit generates a predicted image of a block to be processed by using a first motion vector in operation. Then, using the first candidate having the first motion vector, the HMVP table for storing a plurality of second candidates having the second motion vector used in the processed block in the FIFO method is updated, and the HMVP table is updated. In the update of, it is determined whether or not the size of the processing target block is equal to or less than the threshold size, and if it is determined that the size of the processing target block is equal to or less than the threshold size, the update of the HMVP table is skipped. ..
- the decoding device updates the HMVP table when the size of the block to be processed is larger than the threshold size, so that the processing amount is reduced. Therefore, the processing efficiency of the decoding device is improved.
- the circuit further generates a candidate MVP list including a plurality of predicted motion vector candidates, and uses one of the plurality of predicted motion vector candidates included in the generated candidate MVP list to use the first one.
- the use of the HMVP table is prohibited and the size of the processing target block is larger than the threshold size. In that case, the use of the HMVP table may be permitted.
- the decoding device when the size of the block to be processed is equal to or less than the threshold value, the decoding device generates a candidate MVP list without using the HMVP table, so that the amount of processing is reduced. Therefore, the processing efficiency of the decoding device is improved.
- the size of the processing target block may be defined by the number of pixels in the processing target block.
- the threshold size may be 16 pixels.
- the decoding device skips the update of the HMVP table or generates the candidate MVP list without using the HVMP table, so that the processing amount is reduced. Will be done. Therefore, the processing efficiency of the decoding device is improved.
- the size of the processing target block may be defined by the width or height of the processing target block.
- the decoding apparatus skips updating the HMVP table or does not use the HMVP table. Since the candidate MVP list is generated, the processing amount is reduced. Therefore, the processing efficiency of the decoding device is improved.
- the circuit may use an intermode that refers to a coded picture different from the picture to which the processing target block belongs in generating the predicted image of the processing target block.
- the decoding device acquires a plurality of predicted motion vector candidates for the processing target block based on information such as a plurality of encoded blocks located around the processing target block temporally or spatially. , It is possible to perform prediction processing of the block to be processed.
- the circuit may use an IBC mode that refers to an encoded region of a picture to which the processing target block belongs in generating a predicted image of the processing target block.
- the decoding device can identify and read the reference block based on the motion vector indicating the already decoded and encoded reference block in the same picture as the processing target block.
- the first candidate has first reference picture information corresponding to the first motion vector
- each of the plurality of second candidates has second reference picture information corresponding to the second motion vector.
- the circuit determines whether or not the first candidate matches any of the plurality of second candidates, and the first candidate is any of the plurality of second candidates. If they do not match, the HMVP table may be updated by storing the first candidate in the HMVP table.
- the decoding device expands the range of variations of the first candidate stored in the HMVP table, so that more appropriate prediction candidates for the processing target block can be registered in the candidate MVP list.
- the candidate MVP list may be a candidate MVP list in the AMVP (Adaptive Motion Vector Prediction) mode.
- AMVP Adaptive Motion Vector Prediction
- the decoding device can register the candidate MVP of the HMVP mode in the candidate MVP list in the AMVP mode, so that the prediction accuracy is improved.
- the candidate MVP list may be a candidate MVP list in the merge mode.
- the decoding device can register the candidate MVP of the HMVP mode in the candidate MVP list in the merge mode, so that the prediction accuracy is improved.
- a predicted image of the block to be processed is generated using the first motion vector, and the processed block is used by using the first candidate having the first motion vector.
- the HMVP table that stores a plurality of second candidates having the used second motion vector in the FIFO method is updated, and in the update of the HMVP table, it is determined whether or not the size of the processing target block is equal to or less than the threshold size. If it is determined that the size of the block to be processed is equal to or less than the threshold size, the update of the HMVP table is skipped.
- the device that executes the coding method updates the HMVP table when the size of the processing target block is larger than the threshold size, so that the processing amount is reduced. Therefore, the device that executes the coding method has improved coding efficiency.
- a predicted image of the block to be processed is generated using the first motion vector, and the first candidate having the first motion vector is used in the processed block.
- the HMVP table that stores a plurality of second candidates having the obtained second motion vector in the FIFO method is updated, and in the update of the HMVP table, it is determined whether or not the size of the processing target block is equal to or less than the threshold size. If it is determined that the size of the block to be processed is equal to or less than the threshold size, the update of the HMVP table is skipped.
- the device that executes the decoding method updates the HMVP table when the size of the block to be processed is larger than the threshold size, so that the amount of processing is reduced. Therefore, the processing efficiency of the device that executes the decoding method is improved.
- these comprehensive or specific embodiments may be implemented in a system, device, method, integrated circuit, computer program, or non-temporary recording medium such as a computer-readable CD-ROM, system. , Devices, methods, integrated circuits, computer programs, and any combination of recording media.
- Embodiments are examples of encoding and decoding devices to which the processes and / or configurations described in each aspect of the present disclosure can be applied.
- the processing and / or configuration can also be performed in a coding device and a decoding device different from the embodiment.
- any of the following may be performed.
- Some of the components constituting the encoding device or the decoding device of the embodiment may be combined with the components described in any of the aspects of the present disclosure. , May be combined with a component that includes a part of the function described in any of the aspects of the present disclosure, or a component that performs a part of the processing performed by the component described in each aspect of the present disclosure. May be combined with.
- a component including a part of the functions of the encoding device or the decoding device of the embodiment, or a component performing a part of the process of the encoding device or the decoding device of the embodiment is the A component described in any one of the embodiments, a component having a part of the functions described in any of the aspects of the present disclosure, or a part of the process described in any of the aspects of the present disclosure. It may be combined or replaced with the components to be implemented.
- any one of the plurality of processes included in the method is the same as or similar to the process described in any of the aspects of the present disclosure. It may be replaced or combined with any of the processes.
- the method of carrying out the processing and / or the configuration described in each aspect of the present disclosure is not limited to the coding device or the decoding device of the embodiment.
- the processing and / or configuration may be performed in a device used for a purpose different from the moving image coding or video decoding disclosed in the embodiments.
- FIG. 1 is a block diagram showing a functional configuration of an encoding device 100 according to the embodiment.
- the coding device 100 is a moving image coding device that encodes a moving image in block units.
- the coding device 100 is a device that encodes an image in block units, and includes a dividing unit 102, a subtracting unit 104, a converting unit 106, a quantization unit 108, and entropy coding.
- Unit 110 inverse quantization unit 112, inverse conversion unit 114, addition unit 116, block memory 118, loop filter unit 120, frame memory 122, intra-prediction unit 124, inter-prediction unit 126, and It includes a predictive control unit 128.
- the encoding device 100 is realized by, for example, a general-purpose processor and a memory.
- the processor uses the division unit 102, the subtraction unit 104, the conversion unit 106, the quantization unit 108, the entropy coding unit 110, and the inverse quantization unit 112. , Inverse conversion unit 114, addition unit 116, loop filter unit 120, intra prediction unit 124, inter prediction unit 126, and prediction control unit 128.
- the coding device 100 includes a division unit 102, a subtraction unit 104, a conversion unit 106, a quantization unit 108, an entropy coding unit 110, an inverse quantization unit 112, an inverse conversion unit 114, an addition unit 116, and a loop filter unit 120.
- It may be realized as one or more dedicated electronic circuits corresponding to the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128.
- the overall processing flow of the coding device 100 will be described below, and then each component included in the coding device 100 will be described.
- FIG. 2 is a flowchart showing an example of an overall coding process by the coding device 100.
- the dividing unit 102 of the coding device 100 divides each picture included in the input image which is a moving image into a plurality of fixed size blocks (for example, 128 ⁇ 128 pixels) (step Sa_1). Then, the division unit 102 selects a division pattern (also referred to as a block shape) for the fixed size block (step Sa_2). That is, the division unit 102 further divides the fixed size block into a plurality of blocks constituting the selected division pattern. Then, the coding apparatus 100 performs the processing of steps Sa_3 to Sa_9 on each of the plurality of blocks (that is, the block to be coded).
- a division pattern also referred to as a block shape
- the prediction processing unit including all or a part of the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128 generates a prediction signal (also referred to as a prediction block) of a coded block (also referred to as a current block). (Step Sa_3).
- the subtraction unit 104 generates the difference between the coded block and the predicted block as a predicted residual (also referred to as a difference block) (step Sa_4).
- the conversion unit 106 and the quantization unit 108 generate a plurality of quantization coefficients by performing conversion and quantization on the difference block (step Sa_5).
- a block composed of a plurality of quantization coefficients is also referred to as a coefficient block.
- the entropy coding unit 110 generates a coded signal by encoding (specifically, entropy coding) the coefficient block and the prediction parameter related to the generation of the prediction signal (step). Sa_6).
- the encoded signal is also referred to as an encoded bitstream, a compressed bitstream, or a stream.
- the inverse quantization unit 112 and the inverse conversion unit 114 restore a plurality of predicted residuals (that is, difference blocks) by performing inverse quantization and inverse conversion on the coefficient blocks (step Sa_7).
- the addition unit 116 reconstructs the current block into a reconstructed image (also referred to as a reconstructed block or a decoded image block) by adding a prediction block to the restored difference block (step Sa_8). As a result, a reconstructed image is generated.
- a reconstructed image also referred to as a reconstructed block or a decoded image block
- the loop filter unit 120 performs filtering on the reconstructed image as necessary (step Sa_9).
- step Sa_10 determines whether or not the coding of the entire picture is completed (step Sa_10), and if it is determined that the coding is not completed (No in step Sa_10), the processing from step Sa_2 is repeatedly executed. To do.
- the coding apparatus 100 selects one division pattern for a block of a fixed size and encodes each block according to the division pattern, but according to each of the plurality of division patterns. Each block may be encoded. In this case, the coding apparatus 100 evaluates the cost for each of the plurality of division patterns, and for example, a coded signal obtained by coding according to the division pattern having the lowest cost is used as an output coded signal. You may choose.
- steps Sa_1 to Sa_1 are sequentially performed by the encoding device 100.
- a plurality of processes of some of those processes may be performed in parallel, or the order of those processes may be changed.
- the dividing unit 102 divides each picture included in the input moving image into a plurality of blocks, and outputs each block to the subtracting unit 104.
- the dividing unit 102 first divides the picture into blocks of a fixed size (for example, 128x128). Other fixed block sizes may be adopted. This fixed size block is sometimes referred to as a coded tree unit (CTU).
- CTU coded tree unit
- the division unit 102 divides each of the fixed size blocks into variable size (for example, 64x64 or less) blocks based on, for example, recursive quadtree and / or binary tree block division. To do. That is, the division unit 102 selects a division pattern.
- This variable size block is sometimes referred to as a coding unit (CU), a prediction unit (PU) or a conversion unit (TU).
- CU, PU and TU need not be distinguished, and a part or all blocks in the picture may be a processing unit of CU, PU and TU.
- FIG. 3 is a conceptual diagram showing an example of block division in the embodiment.
- a solid line represents a block boundary by quadtree block division
- a broken line represents a block boundary by binary tree block division.
- the block 10 is a square block (128x128 block) having 128x128 pixels.
- the 128x128 block 10 is first divided into four square 64x64 blocks (quadtree block division).
- the upper left 64x64 block is further vertically divided into two rectangular 32x64 blocks, and the left 32x64 block is further vertically divided into two rectangular 16x64 blocks (binary tree block division). As a result, the upper left 64x64 block is divided into two 16x64 blocks 11 and 12 and a 32x64 block 13.
- the 64x64 block on the upper right is horizontally divided into two rectangular 64x32 blocks 14 and 15 (binary tree block division).
- the lower left 64x64 block is divided into four square 32x32 blocks (quadtree block division). Of the four 32x32 blocks, the upper left block and the lower right block are further divided.
- the upper left 32x32 block is vertically divided into two rectangular 16x32 blocks, and the right 16x32 block is further divided horizontally into two 16x16 blocks (binary block division).
- the lower right 32x32 block is horizontally divided into two 32x16 blocks (binary tree block division).
- the lower left 64x64 block is divided into a 16x32 block 16, two 16x16 blocks 17 and 18, two 32x32 blocks 19 and 20, and two 32x16 blocks 21 and 22.
- the lower right 64x64 block 23 is not divided.
- the block 10 is divided into 13 variable-sized blocks 11 to 23 based on the recursive quadtree and binary tree block divisions.
- Such a division is sometimes called a QTBT (quad-tree plus binary tree) division.
- one block is divided into four or two blocks (quadtree or binary tree block division), but the division is not limited to these.
- one block may be divided into three blocks (ternary tree block division).
- a division including such a ternary tree block division is sometimes called an MBT (multi type tree) division.
- the pictures may be composed of slices or tiles.
- the picture composed of slice units or tile units may be composed of the division unit 102.
- a slice is a basic coding unit that composes a picture.
- the picture is composed of, for example, one or more slices. Further, the slice is composed of one or more consecutive CTUs (Coding Tree Units).
- FIG. 4A is a conceptual diagram showing an example of slice configuration.
- the picture contains 11 x 8 CTUs and is divided into 4 slices (slices 1-4).
- Slice 1 is composed of 16 CTUs
- slice 2 is composed of 21 CTUs
- slice 3 is composed of 29 CTUs
- slice 4 is composed of 22 CTUs.
- each CTU in the picture belongs to any slice.
- the shape of the slice is a horizontally divided picture.
- the slice boundary does not have to be the screen edge, and may be any of the CTU boundaries within the screen.
- the processing order (coding order or decoding order) of CTUs in a slice is, for example, the raster scan order.
- the slice includes header information and encoded data.
- the header information may describe the characteristics of the slice such as the CTU address at the beginning of the slice and the slice type.
- a tile is a unit of a rectangular area that constitutes a picture.
- Each tile may be assigned a number called TileId in raster scan order.
- FIG. 4B is a conceptual diagram showing an example of the tile configuration.
- the picture includes 11 ⁇ 8 CTUs and is divided into four rectangular area tiles (tiles 1-4).
- the processing order of the CTU is changed as compared with the case where the tile is not used. If no tiles are used, multiple CTUs in the picture are processed in raster scan order. If tiles are used, at least one CTU is processed in raster scan order for each of the tiles.
- the processing order of the plurality of CTUs included in tile 1 is from the left end of the first row of tile 1 to the right end of the first row of tile 1, and then the left end of the second row of tile 1. The order is from to the right end of the second row of tile 1.
- one tile may contain one or more slices, and one slice may contain one or more tiles.
- the subtraction unit 104 subtracts the prediction signal (prediction sample input from the prediction control unit 128 shown below) from the original signal (original sample) in block units input from the division unit 102 and divided by the division unit 102. .. That is, the subtraction unit 104 calculates the prediction error (also referred to as the residual) of the block to be coded (hereinafter referred to as the current block). Then, the subtraction unit 104 outputs the calculated prediction error (residual) to the conversion unit 106.
- the prediction error also referred to as the residual of the block to be coded
- the original signal is an input signal of the encoding device 100, and is a signal representing an image of each picture constituting a moving image (for example, a luminance (luma) signal and two color difference (chroma) signals).
- the signal representing the image may be referred to as a sample.
- the conversion unit 106 converts the prediction error in the spatial domain into the conversion coefficient in the frequency domain, and outputs the conversion coefficient to the quantization unit 108. Specifically, the conversion unit 106 performs a predetermined discrete cosine transform (DCT) or discrete sine transform (DST) with respect to the prediction error in the spatial region, for example.
- DCT discrete cosine transform
- DST discrete sine transform
- the predetermined DCT or DST may be predetermined.
- the conversion unit 106 adaptively selects a conversion type from a plurality of conversion types, and converts the prediction error into a conversion coefficient by using a conversion basis function (transform basis function) corresponding to the selected conversion type. You may. Such a conversion may be referred to as EMT (exclusive multi-core transform) or AMT (adaptive multi-core transform).
- EMT exclusive multi-core transform
- AMT adaptive multi-core transform
- the plurality of conversion types include, for example, DCT-II, DCT-V, DCT-VIII, DST-I and DST-VII.
- FIG. 5A is a table showing conversion basis functions corresponding to conversion type examples.
- N indicates the number of input pixels.
- the selection of the conversion type from the plurality of conversion types may depend on, for example, the type of prediction (intra-prediction and inter-prediction) or the intra-prediction mode.
- EMT flag or AMT flag Information indicating whether or not to apply such EMT or AMT
- information indicating the selected conversion type are usually signalized at the CU level.
- the signalization of this information does not have to be limited to the CU level, and may be at another level (for example, bit sequence level, picture level, slice level, tile level or CTU level).
- the conversion unit 106 may reconvert the conversion coefficient (conversion result). Such reconversion may be referred to as AST (adaptive separable transform) or NSST (non-separable second transform). For example, the conversion unit 106 reconverts each subblock (for example, 4x4 subblock) included in the block of the conversion coefficient corresponding to the intra prediction error.
- Information indicating whether or not NSST is applied and information about the transformation matrix used in NSST are usually signalized at the CU level. The signalization of these pieces of information is not limited to the CU level, and may be another level (eg, sequence level, picture level, slice level, tile level or CTU level).
- Separable conversion is a method in which the number of input dimensions is separated for each direction and conversion is performed multiple times.
- Non-Separable conversion is a method in which two or more dimensions are input when the input is multidimensional. This is a method in which the conversion is performed collectively by regarding them as one-dimensional.
- Non-Separable transformation if the input is a 4x4 block, it is regarded as one array with 16 elements, and a 16x16 transformation matrix for that array. There is something like performing conversion processing with.
- a conversion in which a 4 ⁇ 4 input block is regarded as one array having 16 elements and then Givens rotation is performed a plurality of times on the array. Givens Transform) may be held.
- the type of the basis to be converted into the frequency domain can be switched according to the region in the CU.
- SVT spatialally Varying Transfer
- CU is divided into two equal parts in the horizontal or vertical direction, and only one of the regions is converted into the frequency domain.
- the type of conversion basis can be set for each region, for example, DST7 and DCT8 are used. In this example, only one of the two regions in the CU is converted and the other is not converted, but both regions may be converted.
- the division method can be made more flexible by not only dividing into two equal parts but also by dividing into four equal parts or by separately encoding information indicating the division and signaling in the same manner as the CU division.
- the SVT may also be referred to as an SBT (Sub-block Transform).
- the quantization unit 108 quantizes the conversion coefficient output from the conversion unit 106. Specifically, the quantization unit 108 scans the conversion coefficient of the current block in a predetermined scanning order, and quantizes the conversion coefficient based on the quantization parameter (QP) corresponding to the scanned conversion coefficient. Then, the quantization unit 108 outputs the quantized conversion coefficient of the current block (hereinafter referred to as the quantization coefficient) to the entropy coding unit 110 and the inverse quantization unit 112.
- the predetermined scanning order may be predetermined.
- the predetermined scanning order is the order for quantization / inverse quantization of the conversion coefficient.
- a predetermined scanning order may be defined in ascending order of frequency (low frequency to high frequency order) or descending order (high frequency to low frequency order).
- the quantization parameter is a parameter that defines the quantization step (quantization width). For example, as the value of the quantization parameter increases, so does the quantization step. That is, as the value of the quantization parameter increases, the quantization error increases.
- a quantization matrix may be used for quantization.
- quantization matrices may be used corresponding to frequency conversion sizes such as 4x4 and 8x8, prediction modes such as intra-prediction and inter-prediction, and pixel components such as luminance and color difference.
- Quantization refers to digitizing values sampled at predetermined intervals in association with a predetermined level, and is referred to in this technical field by using other expressions such as rounding, rounding, and scaling. You may adopt rounding, rounding, and scaling. Predetermined intervals and levels may be predetermined.
- the quantization matrix As a method of using the quantization matrix, there are a method of using the quantization matrix set directly on the encoder side and a method of using the default quantization matrix (default matrix). On the encoder side, the quantization matrix can be set according to the characteristics of the image by directly setting the quantization matrix. However, in this case, there is a demerit that the coding amount increases due to the coding of the quantization matrix.
- the quantization matrix may be specified by, for example, SPS (sequence parameter set: Sequence Parameter Set) or PPS (picture parameter set: Picture Parameter Set).
- SPS sequence parameter set: Sequence Parameter Set
- PPS picture parameter set: Picture Parameter Set
- SPS and PPS are sometimes referred to simply as parameter sets.
- the entropy coding unit 110 generates a coded signal (coded bit stream) based on the quantization coefficient input from the quantization unit 108. Specifically, the entropy coding unit 110, for example, binarizes the quantization coefficient, arithmetically encodes the binary signal, and outputs a compressed bit stream or sequence.
- the dequantization unit 112 dequantizes the quantization coefficient input from the quantization unit 108. Specifically, the inverse quantization unit 112 inverse-quantizes the quantization coefficient of the current block in a predetermined scanning order. Then, the inverse quantization unit 112 outputs the inversely quantized transform coefficient of the current block to the inverse transform unit 114.
- the predetermined scanning order may be predetermined.
- the inverse transform unit 114 restores the prediction error (residual error) by inversely transforming the transform coefficient input from the inverse quantization unit 112. Specifically, the inverse conversion unit 114 restores the prediction error of the current block by performing an inverse conversion corresponding to the conversion by the conversion unit 106 with respect to the conversion coefficient. Then, the inverse conversion unit 114 outputs the restored prediction error to the addition unit 116.
- the restored prediction error does not match the prediction error calculated by the subtraction unit 104 because the information is usually lost due to quantization. That is, the restored prediction error usually includes the quantization error.
- the addition unit 116 reconstructs the current block by adding the prediction error input from the inverse conversion unit 114 and the prediction sample input from the prediction control unit 128. Then, the addition unit 116 outputs the reconstructed block to the block memory 118 and the loop filter unit 120.
- the reconstruction block may also be referred to as a local decoding block.
- the block memory 118 is, for example, a storage unit that stores a block that is referred to in intra prediction and that is within a current picture to be coded. Specifically, the block memory 118 stores the reconstructed block output from the addition unit 116.
- the frame memory 122 is, for example, a storage unit for storing a reference picture used for inter-prediction, and is sometimes called a frame buffer. Specifically, the frame memory 122 stores the reconstruction block filtered by the loop filter unit 120.
- the loop filter unit 120 applies a loop filter to the block reconstructed by the addition unit 116, and outputs the filtered reconstructed block to the frame memory 122.
- the loop filter is a filter (in-loop filter) used in the coded loop, and includes, for example, a deblocking filter (DF or DBF), a sample adaptive offset (SAO), an adaptive loop filter (ALF), and the like.
- a least squares error filter is applied to remove coding distortion, for example, for each 2x2 subblock in the current block, multiple based on the direction of the local gradient and the activity.
- One filter selected from the filters is applied.
- subblocks for example, 2x2 subblocks
- a plurality of classes for example, 15 or 25 classes.
- the direction value D of the gradient is derived, for example, by comparing the gradients in a plurality of directions (for example, horizontal, vertical and two diagonal directions).
- the gradient activation value A is derived, for example, by adding gradients in a plurality of directions and quantizing the addition result.
- the filter for the subblock is determined from the plurality of filters.
- a circularly symmetric shape is used as the shape of the filter used in ALF.
- 6A-6C are views showing a plurality of examples of filter shapes used in ALF.
- FIG. 6A shows a 5x5 diamond-shaped filter
- FIG. 6B shows a 7x7 diamond-shaped filter
- FIG. 6C shows a 9x9 diamond-shaped filter.
- Information indicating the shape of the filter is usually signalized at the picture level. The signalization of the information indicating the shape of the filter does not have to be limited to the picture level, and may be other levels (for example, sequence level, slice level, tile level, CTU level or CU level).
- ALF on / off may be determined, for example, at the picture level or the CU level. For example, it may be determined whether or not to apply ALF at the CU level for luminance, and whether or not to apply ALF at the picture level for color difference.
- Information indicating ON/OFF of ALF is usually signaled at a picture level or a CU level. The signalization of the information indicating the on / off of ALF does not have to be limited to the picture level or the CU level, and may be at other levels (for example, sequence level, slice level, tile level or CTU level). Good.
- the coefficient set of multiple selectable filters (eg up to 15 or 25 filters) is usually signaled at the picture level.
- the signalization of the coefficient set does not have to be limited to the picture level and may be at other levels (eg, sequence level, slice level, tile level, CTU level, CU level or subblock level).
- the loop filter unit 120 reduces the distortion generated at the block boundary by performing the filtering process on the block boundary of the reconstructed image.
- FIG. 7 is a block diagram showing an example of a detailed configuration of the loop filter unit 120 that functions as a deblocking filter.
- the loop filter unit 120 includes a boundary determination unit 1201, a filter determination unit 1203, a filter processing unit 1205, a processing determination unit 1208, a filter characteristic determination unit 1207, and switches 1202, 1204 and 1206.
- the boundary determination unit 1201 determines whether or not the pixel to be deblocked filtered (that is, the target pixel) exists near the block boundary. Then, the boundary determination unit 1201 outputs the determination result to the switch 1202 and the processing determination unit 1208.
- the switch 1202 When the boundary determination unit 1201 determines that the target pixel exists near the block boundary, the switch 1202 outputs the image before the filter processing to the switch 1204. On the contrary, when the boundary determination unit 1201 determines that the target pixel does not exist near the block boundary, the switch 1202 outputs the image before the filter processing to the switch 1206.
- the filter determination unit 1203 determines whether or not to perform deblocking filter processing on the target pixel based on the pixel value of at least one peripheral pixel in the vicinity of the target pixel. Then, the filter determination unit 1203 outputs the determination result to the switch 1204 and the processing determination unit 1208.
- the switch 1204 When the filter determination unit 1203 determines that the target pixel is to be deblocked and filtered, the switch 1204 outputs the image before the filter processing acquired via the switch 1202 to the filter processing unit 1205. On the contrary, when the filter determination unit 1203 determines that the target pixel is not subjected to the deblocking filter process, the switch 1204 outputs the image before the filter process acquired via the switch 1202 to the switch 1206.
- the filter processing unit 1205 When the image before filtering is acquired via the switches 1202 and 1204, the filter processing unit 1205 performs the deblocking filtering process having the filter characteristic determined by the filter characteristic determining unit 1207 on the target pixel. Execute. Then, the filter processing unit 1205 outputs the filtered pixels to the switch 1206.
- the switch 1206 selectively outputs the pixels that have not been deblocked and filtered by the processing determination unit 1208 and the pixels that have been deblocked and filtered by the filter processing unit 1205.
- the processing determination unit 1208 controls the switch 1206 based on the respective determination results of the boundary determination unit 1201 and the filter determination unit 1203. That is, when the processing determination unit 1208 determines that the target pixel exists near the block boundary by the boundary determination unit 1201 and that the target pixel is subjected to the deblocking filter processing by the filter determination unit 1203. , The pixel subjected to deblocking filter processing is output from the switch 1206. Also, in cases other than the above case, the processing determination unit 1208 causes the switch 1206 to output the pixels that have not been subjected to deblocking filter processing. By repeating such pixel output, the image after the filter processing is output from the switch 1206.
- FIG. 8 is a conceptual diagram showing an example of a deblocking filter having a filter characteristic symmetrical with respect to a block boundary.
- one of two deblocking filters having different characteristics is selected by using the pixel value and the quantization parameter.
- the strong filter as shown in FIG. 8, when the pixels p0 to p2 and the pixels q0 to q2 are present across the block boundary, the pixel values of the pixels q0 to q2 are, for example, the operations shown in the following equation. By performing the above, the pixel values are changed to q'0 to q'2.
- p0 to p2 and q0 to q2 are pixel values of pixels p0 to p2 and pixels q0 to q2, respectively.
- q3 is a pixel value of pixel q3 adjacent to pixel q2 on the side opposite to the block boundary.
- the coefficient multiplied by the pixel value of each pixel used for the deblocking filter processing is the filter coefficient.
- the clip processing may be performed so that the pixel value after the calculation is not set exceeding the threshold value.
- the pixel value after the calculation by the above formula is clipped to "calculation target pixel value ⁇ 2 ⁇ threshold value" using the threshold value determined from the quantization parameter. This makes it possible to prevent excessive smoothing.
- FIG. 9 is a conceptual diagram for explaining a block boundary where deblocking filter processing is performed.
- FIG. 10 is a conceptual diagram showing an example of the Bs value.
- the block boundary on which the deblocking filter processing is performed is, for example, the boundary of a PU (Prediction Unit) or a TU (Transform Unit) of an 8 ⁇ 8 pixel block as shown in FIG.
- the deblocking filtering process may be performed in units of 4 rows or 4 columns.
- the Bs (Boundary Strength) value is determined for the blocks P and Q shown in FIG. 9 as shown in FIG.
- the deblocking filter processing for the color difference signal is performed when the Bs value is 2.
- the deblocking filtering process on the luminance signal is performed when the Bs value is 1 or more and a predetermined condition is satisfied. Predetermined conditions may be predetermined.
- the Bs value determination condition is not limited to that shown in FIG. 10, and may be determined based on other parameters.
- FIG. 11 is a flowchart showing an example of processing performed by the prediction processing unit of the coding apparatus 100.
- the prediction processing unit is composed of all or a part of the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128.
- the prediction processing unit generates a prediction image of the current block (step Sb_1).
- This prediction image is also referred to as a prediction signal or a prediction block.
- the prediction signal includes, for example, an intra prediction signal or an inter prediction signal.
- the prediction processing unit generates a prediction block, a difference block, a coefficient block, a difference block, and a decoded image block, and reconstructs an already obtained reconstructed image. Is used to generate a predicted image of the current block.
- the reconstructed image may be, for example, an image of a reference picture, or an image of a coded block in a current picture that is a picture including a current block.
- the coded block in the current picture is, for example, a block adjacent to the current block.
- FIG. 12 is a flowchart showing another example of the processing performed by the prediction processing unit of the encoding device 100.
- the prediction processing unit generates a prediction image by the first method (step Sc_1a), generates a prediction image by the second method (step Sc_1b), and generates a prediction image by the third method (step Sc_1c).
- the first method, the second method, and the third method are different methods for generating a prediction image, and are, for example, an inter prediction method, an intra prediction method, and other prediction methods, respectively. There may be. In these prediction methods, the above-mentioned reconstructed image may be used.
- the prediction processing unit selects any one of the plurality of prediction images generated in steps Sc_1a, Sc_1b, and Sc_1c (step Sc_2).
- the selection of the predicted image may be performed based on the cost calculated for each generated predicted image. Alternatively, the selection of the predicted image may be performed based on the parameter used in the encoding process.
- the coding apparatus 100 may signal the information for specifying the selected predicted image, method, or mode into a coded signal (also referred to as a coded bitstream).
- the information may be, for example, a flag.
- the decoding device can generate a predicted image according to the scheme or mode selected in the encoding device 100 based on the information.
- the prediction processing unit selects one of the predicted images after generating the predicted image by each method. However, before generating those prediction images, the prediction processing unit selects a method or mode based on the parameters used in the above-mentioned coding process, and generates the prediction image according to the method or mode. May be good.
- the first method and the second method are intra prediction and inter prediction, respectively, and the prediction processing unit obtains a final prediction image for the current block from the prediction images generated according to these prediction methods. You may choose.
- FIG. 13 is a flowchart showing another example of processing performed by the prediction processing unit of the coding apparatus 100.
- the prediction processing unit generates a predicted image by intra prediction (step Sd_1a) and a predicted image by inter prediction (step Sd_1b).
- the prediction image generated by the intra prediction is also referred to as an intra prediction image
- the prediction image generated by the inter prediction is also referred to as an inter prediction image.
- the prediction processing unit evaluates each of the intra prediction image and the inter prediction image (step Sd_2). Costs may be used for this evaluation. That is, the prediction processing unit calculates the cost C of each of the intra prediction image and the inter prediction image.
- D is the coding distortion of the predicted image, and is represented by, for example, the sum of absolute differences between the pixel value of the current block and the pixel value of the predicted image.
- R is a code amount generated in the predicted image, and specifically, is a code amount required for coding motion information or the like for generating a predicted image.
- ⁇ is, for example, an undetermined multiplier of Lagrange.
- the prediction processing unit selects the prediction image for which the smallest cost C is calculated from the intra prediction image and the inter prediction image as the final prediction image of the current block (step Sd_3). That is, the prediction method or mode for generating the predicted image of the current block is selected.
- the intra prediction unit 124 generates a prediction signal (intra prediction signal) by performing intra prediction (also referred to as in-screen prediction) of the current block with reference to a block in the current picture stored in the block memory 118. Specifically, the intra prediction unit 124 generates an intra prediction signal by performing intra prediction with reference to a sample of a block adjacent to the current block (for example, a luminance value and a color difference value), and predicts and controls the intra prediction signal. Output to unit 128.
- intra prediction signal intra prediction signal
- intra prediction also referred to as in-screen prediction
- the intra prediction unit 124 performs intra prediction using one of a plurality of prescribed intra prediction modes.
- the plurality of intra prediction modes usually include one or more non-directional prediction modes and a plurality of directional prediction modes.
- the plurality of prescribed modes may be prescribed in advance.
- One or more non-directional prediction modes are, for example, H. It includes Planar prediction mode and DC prediction mode defined in the H.265/HEVC standard.
- Multiple directional prediction modes are, for example, H. Includes 33 direction prediction modes as defined by the 265 / HEVC standard.
- the plurality of directional prediction modes may include 32 directions (65 directional prediction modes in total) in addition to the 33 directions.
- FIG. 14 is a conceptual diagram showing a total of 67 intra prediction modes (2 non-directional prediction modes and 65 directional prediction modes) that can be used in intra prediction.
- the solid arrow indicates H. It represents the 33 directions defined by the 265 / HEVC standard, and the dashed arrows represent the additional 32 directions (two non-directional prediction modes are not shown in FIG. 14).
- the luminance block may be referred to in the intra prediction of the color difference block. That is, the color difference component of the current block may be predicted based on the luminance component of the current block.
- Such intra-prediction is sometimes called CCLM (cross-component linear model) prediction.
- the intra prediction mode of the color difference block that refers to such a luminance block (for example, called CCLM mode) may be added as one of the intra prediction modes of the color difference block.
- the intra prediction unit 124 may correct the pixel value after intra prediction based on the gradient of reference pixels in the horizontal/vertical directions. Intra-prediction with such a correction is sometimes called PDPC (prophecy departure intra-prescription combination). Information indicating whether or not PDPC is applied (for example, called a PDPC flag) is usually signalized at the CU level. Note that the signaling of this information need not be limited to the CU level, but may be at other levels (eg, sequence level, picture level, slice level, tile level or CTU level).
- the inter-prediction unit 126 refers to a reference picture stored in the frame memory 122 and is different from the current picture, and performs inter-prediction (also referred to as inter-screen prediction) of the current block, thereby performing a prediction signal (inter-screen prediction). Prediction signal) is generated.
- the inter prediction is performed in units of the current block or the current sub block (for example, 4 ⁇ 4 block) in the current block.
- the inter-prediction unit 126 performs motion estimation on the current block or the current sub-block in the reference picture, and finds the reference block or sub-block that best matches the current block or the current sub-block.
- the inter prediction unit 126 acquires motion information (for example, motion vector) that compensates for motion or change from the reference block or subblock to the current block or subblock.
- the inter prediction unit 126 performs motion compensation (or motion prediction) based on the motion information, and generates an inter prediction signal of the current block or sub block.
- the inter-prediction unit 126 outputs the generated inter-prediction signal to the prediction control unit 128.
- the motion information used for motion compensation may be signaled as an inter prediction signal in various forms.
- the motion vector may be signalized.
- the difference between the motion vector and the predicted motion vector may be signalized.
- FIG. 15 is a flowchart showing an example of the basic flow of inter-prediction.
- the inter prediction unit 126 first generates a prediction image (steps Se_1 to Se_3). Next, the subtraction unit 104 generates the difference between the current block and the predicted image as the predicted residual (step Se_4).
- the inter-prediction unit 126 generates the prediction image by determining the motion vector (MV) of the current block (steps Se_1 and Se_2) and performing motion compensation (step Se_3). To do. Further, in determining the MV, the inter-prediction unit 126 determines the MV by selecting the candidate motion vector (candidate MV) (step Se_1) and deriving the MV (step Se_2). The selection of the candidate MV is performed, for example, by selecting at least one candidate MV from the candidate MV list. Further, in MV derivation, the inter-prediction unit 126 determines at least one selected candidate MV as the MV of the current block by selecting at least one candidate MV from at least one candidate MV. You may.
- the inter-prediction unit 126 may determine the MV of the current block by searching the area of the reference picture indicated by the candidate MV for each of the selected at least one candidate MV. It should be noted that searching for the area of the reference picture may be referred to as motion estimation.
- steps Se_1 to Se_3 are performed by the inter-prediction unit 126, but processing such as step Se_1 or step Se_2 may be performed by other components included in the coding apparatus 100. ..
- FIG. 16 is a flowchart showing an example of motion vector derivation.
- the inter prediction unit 126 derives the MV of the current block in a mode in which motion information (for example, MV) is encoded.
- motion information for example, MV
- motion information is encoded as a prediction parameter and signalized. That is, the coded motion information is included in the coded signal (also referred to as a coded bit stream).
- the inter-prediction unit 126 derives the MV in a mode in which the motion information is not encoded. In this case, the motion information is not included in the encoded signal.
- the MV derivation mode may include a normal inter mode, a merge mode, a FRUC mode, an affine mode, etc., which will be described later.
- modes for encoding motion information include a normal intermode, a merge mode, and an affine mode (specifically, an affine intermode and an affine merge mode).
- the motion information may include not only the MV but also the motion vector predictor selection information described later.
- a mode in which motion information is not encoded includes a FRUC mode and the like.
- the inter prediction unit 126 selects a mode for deriving the MV of the current block from these plural modes, and derives the MV of the current block using the selected mode.
- FIG. 17 is a flowchart showing another example of deriving the motion vector.
- the inter-prediction unit 126 derives the MV of the current block in the mode of encoding the difference MV.
- the difference MV is encoded as a prediction parameter and signalized. That is, the encoded difference MV is included in the encoded signal.
- This difference MV is the difference between the MV of the current block and the predicted MV.
- the inter-prediction unit 126 derives the MV in a mode in which the difference MV is not encoded.
- the encoded difference MV is not included in the encoded signal.
- the MV derivation mode includes a normal inter mode, a merge mode, a FRUC mode, and an affine mode, which will be described later.
- modes for encoding the difference MV include a normal intermode and an affine mode (specifically, an affine intermode).
- the mode in which the difference MV is not encoded includes a FRUC mode, a merge mode, an affine mode (specifically, an affine merge mode) and the like.
- the inter prediction unit 126 selects a mode for deriving the MV of the current block from these plural modes, and derives the MV of the current block using the selected mode.
- FIG. 18 is a flowchart showing another example of motion vector derivation.
- the MV derivation mode There are a plurality of modes in the MV derivation mode, that is, the inter prediction mode, and they are roughly classified into a mode in which the difference MV is encoded and a mode in which the difference motion vector is not encoded.
- Modes in which the difference MV is not encoded include a merge mode, a FRUC mode, and an affine mode (specifically, an affine merge mode).
- the merge mode is a mode in which the MV of the current block is derived by selecting a motion vector from the peripheral encoded blocks
- the FRUC mode is a mode in which the MV of the current block is derived. This is a mode for deriving the MV of the current block by performing a search between encoded areas.
- the affine mode is a mode in which the motion vector of each of the plurality of subblocks constituting the current block is derived as the MV of the current block, assuming the affine transformation.
- the inter-prediction unit 126 derives a motion vector in the merge mode when the inter-prediction mode information indicates 0 (0 in Sf_1) (Sf_2). Further, when the inter-prediction mode information indicates 1 (1 in Sf_1), the inter-prediction unit 126 derives a motion vector in the FRUC mode (Sf_3). Further, when the inter prediction mode information indicates 2 (2 in Sf_1), the inter prediction unit 126 derives a motion vector in the affine mode (specifically, the affine merge mode) (Sf_4). Further, when the inter-prediction mode information indicates 3 (3 in Sf_1), the inter-prediction unit 126 derives a motion vector in a mode for encoding the difference MV (for example, normal inter-mode) (Sf_5).
- the inter-prediction mode information indicates 0 (0 in Sf_1) (Sf_2). Further, when the inter-prediction mode information indicates 1 (1 in Sf_1), the inter-prediction unit 126 derives a motion vector in
- the normal inter-mode is an inter-prediction mode in which the MV of the current block is derived from the area of the reference picture indicated by the candidate MV based on a block similar to the image of the current block. Further, in this normal inter mode, the difference MV is encoded.
- FIG. 19 is a flowchart showing an example of inter prediction in the normal inter mode.
- the inter-prediction unit 126 acquires a plurality of candidate MVs for the current block based on information such as MVs of a plurality of encoded blocks around the current block temporally or spatially (step). Sg_1). That is, the inter-prediction unit 126 creates a candidate MV list.
- the inter prediction unit 126 determines each of N (N is an integer of 2 or more) candidate MVs among the plurality of candidate MVs acquired in step Sg_1 as a motion vector predictor candidate (also referred to as a predicted MV candidate). As a result, extraction is performed according to a predetermined priority (step Sg_2). The priority may be predetermined for each of the N candidate MVs.
- the inter-prediction unit 126 selects one predicted motion vector candidate from the N predicted motion vector candidates as the predicted motion vector (also referred to as predicted MV) of the current block (step Sg_3). At this time, the inter-prediction unit 126 encodes the predicted motion vector selection information for identifying the selected predicted motion vector into the stream.
- the stream is the above-mentioned coded signal or coded bit stream.
- the inter-prediction unit 126 refers to the encoded reference picture and derives the MV of the current block (step Sg_4). At this time, the inter-prediction unit 126 further encodes the difference value between the derived MV and the predicted motion vector into the stream as the difference MV.
- the coded reference picture is a picture composed of a plurality of blocks reconstructed after coding.
- the inter-prediction unit 126 generates a prediction image of the current block by performing motion compensation for the current block using the derived MV and the encoded reference picture (step Sg_5).
- the prediction image is the above-mentioned inter-prediction signal.
- the information including the coded signal indicating the inter-prediction mode (normal inter-mode in the above example) used for generating the prediction image is encoded as, for example, a prediction parameter.
- the candidate MV list may be commonly used with lists used for other modes. Further, the process related to the candidate MV list may be applied to the process related to the list used in other modes.
- the processing related to this candidate MV list is, for example, extraction or selection of candidate MVs from the candidate MV list, rearrangement of candidate MVs, deletion of candidate MVs, and the like.
- the merge mode is an inter-prediction mode in which the candidate MV is derived from the candidate MV list by selecting the candidate MV as the MV of the current block.
- FIG. 20 is a flowchart showing an example of inter-prediction in the merge mode.
- the inter-prediction unit 126 acquires a plurality of candidate MVs for the current block based on information such as MVs of a plurality of encoded blocks around the current block temporally or spatially (step). Sh_1). That is, the inter-prediction unit 126 creates a candidate MV list.
- the inter-prediction unit 126 derives the MV of the current block by selecting one candidate MV from the plurality of candidate MVs acquired in step Sh_1 (step Sh_2). At this time, the inter-prediction unit 126 encodes the MV selection information for identifying the selected candidate MV into the stream.
- the inter-prediction unit 126 generates a prediction image of the current block by performing motion compensation for the current block using the derived MV and the encoded reference picture (step Sh_3).
- the information including the coded signal indicating the inter-prediction mode (merge mode in the above example) used for generating the prediction image is encoded as, for example, a prediction parameter.
- FIG. 21 is a conceptual diagram for explaining an example of the motion vector derivation process of the current picture in the merge mode.
- Candidates for the prediction MV include the spatially adjacent prediction MV, which is the MV of a plurality of coded blocks located spatially around the target block, and the block in the vicinity that projects the position of the target block in the coded reference picture.
- a time-adjacent prediction MV which is an MV having the MV
- a combination prediction MV which is an MV generated by combining the MV values of the space-adjacent prediction MV and the time-adjacent prediction MV
- a zero prediction MV which is an MV having a value of zero.
- variable length coding unit the message_idx, which is a signal indicating which predicted MV is selected, is described in the stream and encoded.
- the prediction MVs registered in the prediction MV list described in FIG. 21 are examples, and the number may be different from the number in the drawing, or may be a configuration that does not include some types of the prediction MV in the drawing.
- the configuration may be such that a predicted MV other than the type of predicted MV in the figure is added.
- the final MV may be determined by performing a DMVR (decoder motion vector refinement) process described later using the MV of the target block derived by the merge mode.
- DMVR decoder motion vector refinement
- the candidate for the predicted MV is the above-mentioned candidate MV
- the predicted MV list is the above-mentioned candidate MV list.
- the candidate MV list may be referred to as a candidate list.
- merge_idx is MV selection information.
- the motion information may be derived on the decoding device side without being signalized from the coding device side.
- H The merge mode specified in the 265 / HEVC standard may be used.
- motion information may be derived by performing motion search on the decoding device side. In the embodiment, the decoding device side performs the motion search without using the pixel value of the current block.
- the mode in which the motion search is performed on the decoding device side may be called a PMMVD (pattern matched motion vector derivation) mode or a FRUC (frame rate up-conversion) mode.
- PMMVD pattern matched motion vector derivation
- FRUC frame rate up-conversion
- FIG. 22 shows an example of FRUC processing in the form of a flowchart.
- a list of a plurality of candidates ie, a candidate MV list, each of which has a predicted motion vector (MV)). (May be common with the merge list) is generated (step Si_1).
- the best candidate MV is selected from the plurality of candidate MVs registered in the candidate MV list (step Si_2). For example, the evaluation value of each candidate MV included in the candidate MV list is calculated, and one candidate MV is selected based on the evaluation value.
- a motion vector for the current block is derived based on the selected candidate motion vector (step Si_4).
- the motion vector of the selected candidate is derived as it is as a motion vector for the current block.
- a motion vector for the current block may be derived by performing pattern matching in the peripheral region of the position in the reference picture corresponding to the selected candidate motion vector. That is, the area around the best candidate MV is searched for using the pattern matching in the reference picture and the evaluation value, and if there is an MV with a better evaluation value, the best candidate MV is set to the MV. It may be updated to be the final MV of the current block. It is also possible to configure the configuration so that the process of updating to the MV having a better evaluation value is not performed.
- the inter-prediction unit 126 generates a prediction image of the current block by performing motion compensation for the current block using the derived MV and the encoded reference picture (step Si_5).
- the evaluation value may be calculated by various methods. For example, a reconstructed image of a region in a reference picture corresponding to a motion vector and a predetermined region (that region is, for example, the region of another reference picture or the region of an adjacent block of the current picture, as shown below. May be used).
- the predetermined area may be predetermined.
- the difference between the pixel values of the two reconstructed images may be calculated and used as the evaluation value of the motion vector.
- the evaluation value may be calculated by using other information in addition to the difference value.
- one candidate MV included in the candidate MV list (for example, merge list) is selected as the start point of the search by pattern matching.
- a first pattern matching or a second pattern matching can be used as the pattern matching.
- the first pattern matching and the second pattern matching may be referred to as bilateral matching (bilateral matching) and template matching (template matching), respectively.
- MV derivation>FRUC> Bilateral matching In the first pattern matching, pattern matching is performed between two blocks in two different reference pictures, which are along a motion trajectory of the current block. Therefore, in the first pattern matching, a region in another reference picture along the movement trajectory of the current block is used as a predetermined region for calculating the evaluation value of the candidate described above.
- the predetermined area may be predetermined.
- FIG. 23 is a conceptual diagram for explaining an example of first pattern matching (bilateral matching) between two blocks in two reference pictures along a motion trajectory.
- first pattern matching two blocks along the motion trajectory of the current block (Cur block) are included in a pair of two blocks in two different reference pictures (Ref0, Ref1).
- Two motion vectors (MV0, MV1) are derived by searching for the best matching pair. Specifically, for the current block, the reconstructed image at the specified position in the first coded reference picture (Ref0) specified by the candidate MV and the symmetric MV obtained by scaling the candidate MV at the display time interval.
- the difference with the reconstructed image at the designated position in the second coded reference picture (Ref1) designated by is derived, and the evaluation value is calculated using the obtained difference value. It is possible to select the candidate MV having the best evaluation value among the plurality of candidate MVs as the final MV, which can bring about good results.
- the motion vector (MV0, MV1) pointing to the two reference blocks is the temporal distance between the current picture (Cur Pic) and the two reference pictures (Ref0, Ref1). It is proportional to (TD0, TD1).
- the first pattern matching is a mirror-symmetric bidirectional motion vector. Is derived.
- FIG. 24 is a conceptual diagram for explaining an example of pattern matching (template matching) between a template in the current picture and a block in the reference picture.
- the current block is searched by searching the reference picture (Ref0) for the block that most matches the block adjacent to the current block (Cur block) in the current picture (CurPic).
- the motion vector of is derived.
- the reconstructed image of the left adjacent and/or upper adjacent encoded areas and the equivalent in the encoded reference picture (Ref0) designated by the candidate MV are equal.
- the difference with the reconstructed image at the position is derived, the evaluation value is calculated using the obtained difference value, and the candidate MV having the best evaluation value among the plurality of candidate MVs is selected as the best candidate MV. It is possible.
- Information indicating whether or not to apply such a FRUC mode may be signalized at the CU level. Further, when the FRUC mode is applied (for example, when the FRUC flag is true), information indicating an applicable pattern matching method (first pattern matching or second pattern matching) may be signalized at the CU level. .. Note that the signaling of this information does not have to be limited to the CU level and may be at other levels (eg, sequence level, picture level, slice level, tile level, CTU level or subblock level). ..
- FIG. 25A is a conceptual diagram for explaining an example of deriving a motion vector in sub-block units based on motion vectors of a plurality of adjacent blocks.
- the current block includes 16 4x4 subblocks.
- the motion vector v 0 of the upper left corner control point of the current block is derived based on the motion vector of the adjacent block, and similarly, the motion vector v of the upper right corner control point of the current block is derived based on the motion vector of the adjacent subblock. 1 is derived.
- two motion vectors v 0 and v 1 may be projected by the following equation (1A), and the motion vectors (v x , v y ) of each subblock in the current block may be derived.
- x and y indicate the horizontal position and vertical position of the sub-block, respectively, and w indicates a predetermined weighting coefficient.
- the predetermined weighting factor may be predetermined.
- Information indicating such an affine mode may be signalized at the CU level.
- the signalization of the information indicating the affine mode does not have to be limited to the CU level, but may be another level (for example, a sequence level, a picture level, a slice level, a tile level, a CTU level or a sub-block level). You may.
- an affine mode may include several modes in which the method of deriving the motion vector of the upper left and upper right corner control points is different.
- FIG. 25B is a conceptual diagram for explaining an example of deriving a motion vector in sub-block units in an affine mode having three control points.
- the current block includes 16 4x4 subblocks.
- the motion vector v 0 of the upper left corner control point of the current block is derived based on the motion vector of the adjacent block
- the motion vector v 1 of the upper right corner control point of the current block is derived based on the motion vector of the adjacent block.
- the motion vector v 2 of the lower left corner control point of the current block is derived based on the motion vectors of the adjacent blocks.
- three motion vectors v 0 , v 1 and v 2 may be projected by the following equation (1B), and the motion vectors (v x , v y ) of each subblock in the current block are derived. Good.
- x and y indicate the horizontal position and the vertical position of the center of the subblock, respectively, w indicates the width of the current block, and h indicates the height of the current block.
- Affine modes with different numbers of control points may be switched at the CU level and signaled. Even if the information indicating the number of control points in the affine mode used at the CU level is signalized at another level (for example, sequence level, picture level, slice level, tile level, CTU level or subblock level). Good.
- the affine mode having such three control points may include some modes in which the method of deriving the motion vector of the upper left, upper right and lower left corner control points is different.
- FIG. 26A, 26B and 26C are conceptual diagrams for explaining the affine merge mode.
- coded block A left
- block B upper
- block C upper right
- block D lower left
- block E upper left
- the predicted motion vectors of the control points of the current block are calculated based on the plurality of motion vectors corresponding to the blocks encoded in the affine mode. Specifically, these blocks are inspected in the order of encoded block A (left), block B (top), block C (upper right), block D (lower left) and block E (upper left) in affine mode. The first valid coded block is identified.
- the predicted motion vector of the control point of the current block is calculated based on the plurality of motion vectors corresponding to the specified block.
- the upper left corner and the upper right corner of the encoded block including the block A are motion projected onto the position vector v 3 and v 4 is derived. Then, the predicted motion vector v 0 of the control point at the upper left corner of the current block and the predicted motion vector v 1 of the control point at the upper right corner of the current block are calculated from the derived motion vectors v 3 and v 4 .
- the block A adjacent to the left of the current block is encoded in the affine mode having three control points
- the upper left corner and the upper right corner of the encoded block including the block A.
- the motion vectors v 3 , v 4 and v 5 projected at the position of the lower left corner are derived.
- the predicted motion vector v 0 of the control point in the upper left corner of the current block the predicted motion vector v 1 of the control point in the upper right corner, and the control of the lower left corner. predicted motion vector v 2 of the points are calculated.
- this predicted motion vector deriving method may be used for deriving the predicted motion vector of each control point of the current block in step Sj_1 of FIG. 29, which will be described later.
- FIG. 27 is a flowchart showing an example of the affine merge mode.
- the inter-prediction unit 126 derives each prediction MV of the control point of the current block (step Sk_1).
- the control points are the upper left corner and upper right corner points of the current block as shown in FIG. 25A, or the upper left corner, upper right corner and lower left corner point of the current block as shown in FIG. 25B.
- the inter-prediction unit 126 performs the encoded block A (left), block B (top), block C (upper right), block D (lower left), and block E (upper left) in that order. Inspect these blocks to identify the first valid block encoded in affine mode.
- the inter-prediction unit 126 moves the motion vectors v 3 of the upper left corner and the upper right corner of the coded block including the block A. From and v 4 , the motion vector v 0 of the control point in the upper left corner of the current block and the motion vector v 1 of the control point in the upper right corner are calculated. For example, the inter-prediction unit 126 projects the motion vectors v 3 and v 4 of the upper left corner and the upper right corner of the coded block onto the current block, so that the predicted motion vector v 0 of the control point of the upper left corner of the current block. If, to calculate the predicted motion vector v 1 of the control point in the upper right corner.
- the inter-prediction unit 126 moves the upper left, upper right, and lower left corners of the coded block containing block A. From the vectors v 3 , v 4 and v 5 , the motion vector v 0 of the control point in the upper left corner of the current block, the motion vector v 1 of the control point in the upper right corner, and the motion vector v 2 of the control point in the lower left corner are calculated. To do.
- inter prediction unit 126 For example, inter prediction unit 126, the upper left corner of the encoded blocks, the motion vector v 3, v 4 and v 5 in the upper right corner and lower left corner, by projecting the current block, the control point of the upper left corner of the current block
- the predicted motion vector v 0 of, the predicted motion vector v 1 of the control point in the upper right corner, and the motion vector v 2 of the control point in the lower left corner are calculated.
- the inter-prediction unit 126 performs motion compensation for each of the plurality of sub-blocks included in the current block. That is, the inter-prediction unit 126 has two predicted motion vectors v 0 and v 1 and the above equation (1A), or three predicted motion vectors v 0 , v 1 and v 2 for each of the plurality of subblocks.
- the motion vector of the subblock is calculated as an affine MV (step Sk_2).
- the inter prediction unit 126 performs motion compensation on the sub-block using the affine MV and the encoded reference picture (step Sk_3). As a result, motion compensation is performed on the current block, and a predicted image of the current block is generated.
- FIG. 28A is a conceptual diagram for explaining an affine inter mode having two control points.
- the motion vector selected from the motion vectors of the coded blocks A, B and C adjacent to the current block predicts the control point in the upper left corner of the current block. It is used as the motion vector v 0 .
- motion vectors selected from the motion vectors of the encoded block D and block E is adjacent to the current block are used as predicted motion vector v 1 of the control point of the upper-right corner of the current block.
- FIG. 28B is a conceptual diagram for explaining an affine intermode having three control points.
- the motion vector selected from the motion vectors of the coded blocks A, B and C adjacent to the current block is the prediction of the control point at the upper left corner of the current block. It is used as the motion vector v 0 .
- motion vectors selected from the motion vectors of the encoded block D and block E is adjacent to the current block are used as predicted motion vector v 1 of the control point of the upper-right corner of the current block.
- motion vectors selected from the motion vectors of the encoded block F and block G adjacent to the current block are used as predicted motion vector v 2 of the control points of the lower left corner of the current block.
- FIG. 29 is a flowchart showing an example of the affine intermode.
- the inter prediction unit 126 predicts the prediction MV (v 0 , v 1 ) or (v 0 , v 1 , v of each of two or three control points of the current block. 2 ) is derived (step Sj_1).
- the control point is a point at the upper left corner, the upper right corner, or the lower left corner of the current block.
- the inter-prediction unit 126 predicts the control point of the current block by selecting the motion vector of any of the coded blocks in the vicinity of each control point of the current block shown in FIG. 28A or FIG. 28B.
- the motion vector (v 0 , v 1 ) or (v 0 , v 1 , v 2 ) is derived.
- the inter prediction unit 126 encodes the motion vector predictor selection information for identifying the two selected motion vectors into a stream.
- the inter-prediction unit 126 determines which block motion vector is selected as the predicted motion vector of the control point from the encoded blocks adjacent to the current block by using cost evaluation or the like, and which predicted motion vector is selected. A flag indicating whether the selection has been made may be described in the bitstream.
- the inter-prediction unit 126 performs motion search (steps Sj_3 and Sj_4) while updating the predicted motion vectors selected or derived in step Sj_1, respectively (step Sj_2). That is, the inter prediction unit 126 calculates the motion vector of each sub-block corresponding to the updated motion vector predictor as the affine MV using the above formula (1A) or formula (1B) (step Sj_3). Then, the inter-prediction unit 126 performs motion compensation for each subblock using the affine MV and the encoded reference picture (step Sj_4).
- the inter-prediction unit 126 determines, for example, the predicted motion vector at which the lowest cost can be obtained as the motion vector of the control point (step Sj_5). At this time, the inter-prediction unit 126 further encodes the difference value between the determined MV and the predicted motion vector into the stream as the difference MV.
- the inter-prediction unit 126 generates a prediction image of the current block by performing motion compensation for the current block using the determined MV and the encoded reference picture (step Sj_6).
- FIGS. 30A and 30B are conceptual diagrams for explaining a method of deriving a prediction vector of control points when the number of control points is different between the encoded block and the current block.
- the current block has three control points of the upper left corner, the upper right corner, and the lower left corner, and the block A adjacent to the left of the current block is encoded in affine mode having two control points. If it is, the motion vector v 3 and v 4 projected onto the position of the upper left corner and upper right corner of the encoded blocks containing the block a is derived. Then, the predicted motion vector v 0 of the control point at the upper left corner of the current block and the predicted motion vector v 1 of the control point at the upper right corner of the current block are calculated from the derived motion vectors v 3 and v 4 . Further, the predicted motion vector v 2 of the control point at the lower left corner is calculated from the derived motion vectors v 0 and v 1 .
- the current block is encoded in an affine mode having two control points, an upper left corner and an upper right corner, and block A adjacent to the left of the current block has three control points.
- the motion vectors v 3 , v 4 and v 5 projected at the positions of the upper left corner, the upper right corner and the lower left corner of the encoded block including the block A are derived.
- the predicted motion vector v 0 of the control point at the upper left corner of the current block and the predicted motion vector v 1 of the control point at the upper right corner of the current block are calculated from the derived motion vectors v 3 , v 4 and v 5 .
- This predicted motion vector deriving method may be used for deriving the predicted motion vector of each control point of the current block in step Sj_1 of FIG. 29.
- FIG. 31A is a flowchart showing the relationship between the merge mode and DMVR.
- the inter-prediction unit 126 derives the motion vector of the current block in the merge mode (step Sl_1). Next, the inter prediction unit 126 determines whether or not to search a motion vector, that is, a motion search (step Sl_2). Here, when the inter prediction unit 126 determines not to perform the motion search (No in step Sl_2), the inter prediction unit 126 determines the motion vector derived in step Sl_1 as the final motion vector for the current block (step Sl_4). That is, in this case, the motion vector of the current block is determined in the merge mode.
- step Sl_3 the motion vector of the current block is determined by DMVR.
- FIG. 31B is a conceptual diagram for explaining an example of DMVR processing for determining MV.
- the optimum MVP set in the current block (for example, in merge mode) is set as the candidate MV.
- the candidate MV (L0) the reference pixel is specified from the first reference picture (L0) which is the encoded picture in the L0 direction.
- the reference pixel is specified from the second reference picture (L1) which is the encoded picture in the L1 direction.
- a template is generated by averaging these reference pixels.
- the peripheral regions of the candidate MVs of the first reference picture (L0) and the second reference picture (L1) are searched respectively, and the MV having the lowest cost is determined as the final MV.
- the cost value may be calculated using, for example, a difference value between each pixel value of the template and each pixel value of the search area, a candidate MV value, and the like.
- the coding device and the decoding device described later basically have the same processing configuration and operation described here.
- any processing may be used as long as it is a processing that can search the periphery of the candidate MV and derive the final MV.
- BIO / OBMC In motion compensation, there is a mode in which a predicted image is generated and the predicted image is corrected.
- the mode is, for example, BIO and OBMC described later.
- FIG. 32 is a flowchart showing an example of generating a predicted image.
- the inter prediction unit 126 generates a predicted image (step Sm_1), and corrects the predicted image according to, for example, one of the above modes (step Sm_2).
- FIG. 33 is a flowchart showing another example of generating a predicted image.
- the inter-prediction unit 126 determines the motion vector of the current block (step Sn_1). Next, the inter-prediction unit 126 generates a prediction image (step Sn_2) and determines whether or not to perform correction processing (step Sn_3). Here, when the inter-prediction unit 126 determines that the correction process is to be performed (Yes in step Sn_3), the inter-prediction unit 126 corrects the predicted image to generate a final predicted image (step Sn_4). On the other hand, when the inter-prediction unit 126 determines that the correction process is not performed (No in step Sn_3), the inter-prediction unit 126 outputs the predicted image as a final predicted image without correcting it (step Sn_5).
- the mode is, for example, LIC described later.
- FIG. 34 is a flowchart showing another example of generating a predicted image.
- the inter-prediction unit 126 derives the motion vector of the current block (step So_1). Next, the inter-prediction unit 126 determines whether or not to perform the luminance correction process (step So_2). Here, when the inter-prediction unit 126 determines that the luminance correction process is to be performed (Yes in step So_2), the inter-prediction unit 126 generates a predicted image while performing the luminance correction (step So_3). That is, the predicted image is generated by the LIC. On the other hand, when the inter prediction unit 126 determines that the brightness correction process is not performed (No in step So_2), the inter prediction unit 126 generates a predicted image by normal motion compensation without performing the brightness correction (step So_4).
- An inter-prediction signal may be generated by using not only the motion information of the current block obtained by the motion search but also the motion information of the adjacent block. Specifically, by adding the prediction signal based on the motion information (in the reference picture) obtained by the motion search and the prediction signal based on the motion information of the adjacent block (in the current picture) by weighting, the current An inter-prediction signal may be generated for each sub-block within a block.
- Such inter-prediction (motion compensation) is sometimes called OBMC (overlapped block motion compensation).
- information indicating the size of the subblock for OBMC may be signalized at the sequence level. Further, information indicating whether or not to apply the OBMC mode (for example, called an OBMC flag) may be signalized at the CU level.
- the signalization level of this information does not have to be limited to the sequence level and the CU level, and may be other levels (for example, picture level, slice level, tile level, CTU level or subblock level). Good.
- 35 and 36 are a flowchart and a conceptual diagram for explaining the outline of the predicted image correction process by the OBMC process.
- a predicted image (Pred) by normal motion compensation is acquired using the motion vector (MV) assigned to the processing target (current) block.
- MV motion vector assigned to the processing target (current) block.
- the arrow “MV” points to a reference picture and indicates what the current block of the current picture refers to in order to obtain a predicted image.
- the motion vector (MV_L) already derived for the coded left adjacent block is applied (reused) to the coded target block to acquire the predicted image (Pred_L).
- the motion vector (MV_L) is indicated by the arrow "MV_L” pointing from the current block to the reference picture.
- the first correction of the predicted image is performed by superimposing the two predicted images Pred and Pred_L. This has the effect of mixing the boundaries between adjacent blocks.
- the motion vector (MV_U) already derived for the encoded upper adjacent block is applied (reused) to the coded target block to acquire the predicted image (Pred_U).
- the motion vector (MV_U) is indicated by an arrow “MV_U” pointing from the current block to the reference picture.
- the predicted image Pred_U is superposed on the predicted image (for example, Pred and Pred_L) that has been corrected for the first time, so that the predicted image is corrected for the second time. This has the effect of mixing the boundaries between adjacent blocks.
- the predicted image obtained by the second correction is the final predicted image of the current block in which the boundaries with the adjacent blocks are mixed (smoothed).
- the above example is a two-pass correction method using blocks adjacent to the left and above, but the correction method is a three-pass or more pass method using blocks adjacent to the right and / or adjacent to the bottom. It may be the correction method of.
- the area to be superimposed may not be the pixel area of the entire block, but only a part of the area near the block boundary.
- the OBMC prediction image correction process for obtaining one prediction image Pred by superimposing additional prediction images Pred_L and Pred_U from one reference picture has been described.
- the same process may be applied to each of the plurality of reference pictures.
- by performing image correction of OBMC based on a plurality of reference pictures after obtaining a corrected predicted image from each reference picture, further superimposing the obtained plurality of corrected predicted images. To get the final predicted image.
- the unit of the target block may be a prediction block unit or a sub-block unit obtained by further dividing the prediction block.
- the encoding device may determine whether the target block belongs to a complex region of motion.
- the value 1 is set as obmc_flag and OBMC processing is applied to perform coding.
- the coding device does not belong to the complicated region of movement, it is set as obmc_flag.
- the value 0 is set and the block is encoded without applying the OBMC processing.
- the decoding device by decoding obmc_flag described in the stream (for example, a compression sequence), whether or not to apply the OBMC process is switched according to the value and decoding is performed.
- the inter-prediction unit 126 generates one rectangular prediction image for the rectangular current block.
- the inter-prediction unit 126 generates a plurality of prediction images having a shape different from that of the rectangle with respect to the current block of the rectangle, and generates a final prediction image of the rectangle by combining the plurality of prediction images.
- the shape different from the rectangle may be, for example, a triangle.
- FIG. 37 is a conceptual diagram for explaining the generation of the predicted images of the two triangles.
- the inter-prediction unit 126 generates a triangle prediction image by performing motion compensation for the first partition of the triangle in the current block using the first MV of the first partition. Similarly, the inter-prediction unit 126 generates a triangle prediction image by performing motion compensation on the second partition of the triangle in the current block using the second MV of the second partition. Then, the inter prediction unit 126 generates a prediction image having the same rectangle as the current block by combining these prediction images.
- the first partition and the second partition are triangular, but they may be trapezoidal or have different shapes. Further, in the example shown in FIG. 37, the current block is composed of two partitions, but it may be composed of three or more partitions.
- first partition and the second partition may overlap. That is, the first partition and the second partition may include the same pixel area.
- the predicted image of the current block may be generated by using the predicted image in the first partition and the predicted image in the second partition.
- the predicted image is generated by inter-prediction for both partitions, but the predicted image may be generated by intra-prediction for at least one partition.
- BIO basic-directional optical flow
- FIG. 38 is a conceptual diagram for explaining a model assuming constant velocity linear motion.
- (vx, by) indicates a velocity vector
- ⁇ 0 and ⁇ 1 indicate the temporal distances between the current picture (Cur Pic) and the two reference pictures (Ref0, Ref1, respectively).
- (MVx0, MVy0) indicates a motion vector corresponding to the reference picture Ref0
- (MVx1, MVy1) indicates a motion vector corresponding to the reference picture Ref1.
- This optical flow equation is (i) the time derivative of the luminance value, (ii) the product of the horizontal velocity and the horizontal component of the spatial gradient of the reference image, and (iii) the vertical velocity and the spatial gradient of the reference image. We show that the sum of the product of the vertical components of is equal to zero. Based on the combination of this optical flow equation and Hermite interpolation, the motion vector in block units obtained from the merge list or the like may be corrected in pixel units.
- the motion vector may be derived on the decoding device side by a method different from the derivation of the motion vector based on the model assuming constant velocity linear motion.
- a motion vector may be derived in subblock units based on the motion vectors of a plurality of adjacent blocks.
- FIG. 39 is a conceptual diagram for explaining an example of a predicted image generation method using the luminance correction process by the LIC process.
- the MV is derived from the encoded reference picture, and the reference image corresponding to the current block is acquired.
- the current block information indicating how the brightness value has changed between the reference picture and the current picture is extracted.
- This extraction is performed using the luminance pixel values of the coded left adjacent reference area (peripheral reference area) and the coded upper adjacent reference area (peripheral reference area) in the current picture, and the reference picture specified by the derived MV. It is performed based on the luminance pixel value at the same position. Then, the brightness correction parameter is calculated using the information indicating how the brightness value has changed.
- a predicted image for the current block is generated by performing a brightness correction process that applies the brightness correction parameter to the reference image in the reference picture specified by the MV.
- the shape of the peripheral reference region in FIG. 39 is an example, and other shapes may be used.
- the process of generating the predicted image from one reference picture has been described here, the same applies to the case where the predicted image is generated from a plurality of reference pictures, and the reference image acquired from each reference picture is described above.
- the predicted image may be generated after performing the luminance correction process in the same manner as in the above.
- lic_flag is a signal indicating whether or not to apply the LIC processing.
- the value is set as lic_flag. 1 is set and LIC processing is applied to perform coding, and if it does not belong to the region where the luminance change occurs, a value 0 is set as lic_flag and coding is performed without applying LIC processing.
- the decoding device by decoding the lic_flag described in the stream, whether or not to apply the LIC processing may be switched according to the value to perform the decoding.
- determining whether or not to apply the LIC processing for example, there is also a method of determining whether or not the LIC processing is applied in the peripheral block.
- determining whether or not the LIC processing is applied in the peripheral block.
- the peripheral encoded blocks selected when deriving the MV in the merge mode processing are encoded by applying the LIC processing. ..
- Encoding is performed by switching whether or not to apply the LIC process according to the result. Even in the case of this example, the same processing is applied to the processing on the decoding device side.
- the inter-prediction unit 126 derives a motion vector for acquiring a reference image corresponding to a coded target block from a reference picture which is a coded picture.
- the inter-prediction unit 126 generates a prediction image for the coded block by performing brightness correction processing on the reference image in the reference picture specified by the motion vector using the brightness correction parameter.
- the luminance pixel value in the reference image is p2
- the luminance pixel value of the predicted image after the luminance correction process is p3.
- the shape of the peripheral reference area in FIG. 39 is an example, and shapes other than this may be used. Moreover, a part of the peripheral reference area shown in FIG. 39 may be used. For example, a region including a predetermined number of pixels thinned out from each of the upper adjacent pixel and the left adjacent pixel may be used as the peripheral reference region. Further, the peripheral reference area is not limited to the area adjacent to the coded target block, and may be an area not adjacent to the coded target block. A predetermined number of pixels may be predetermined.
- the peripheral reference area in the reference picture is an area specified by the motion vector of the coded target picture from the peripheral reference area in the coded target picture, but is represented by another motion vector. It may be a designated area.
- the other motion vector may be a motion vector of a peripheral reference region in the picture to be encoded.
- the LIC processing may be applied not only to the luminance but also to the color difference.
- correction parameters may be derived individually for each of Y, Cb, and Cr, or a common correction parameter may be used for any of them.
- the LIC processing may be applied in units of subblocks.
- the correction parameter may be derived using the peripheral reference area of the current subblock and the peripheral reference area of the reference subblock in the reference picture specified by the MV of the current subblock.
- the prediction control unit 128 selects either an intra prediction signal (a signal output from the intra prediction unit 124) or an inter prediction signal (a signal output from the inter prediction unit 126), and subtracts the selected signal as a prediction signal. Output to unit 104 and addition unit 116.
- the prediction control unit 128 may output the prediction parameters input to the entropy coding unit 110.
- the entropy coding unit 110 may generate a coded bit stream (or sequence) based on the prediction parameter input from the prediction control unit 128 and the quantization coefficient input from the quantization unit 108.
- the prediction parameter may be used in the decoding device.
- the decoding device may receive the coded bit stream, decode it, and perform the same processing as the prediction processing performed by the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128.
- the prediction parameter is a selected prediction signal (for example, a motion vector, a prediction type, or a prediction mode used by the intra prediction unit 124 or the inter prediction unit 126), or an intra prediction unit 124, an inter prediction unit 126, and a prediction control unit. Any index, flag, or value based on or indicative of the prediction process performed at 128 may be included.
- FIG. 40 is a block diagram showing an implementation example of the coding device 100.
- the coding device 100 includes a processor a1 and a memory a2.
- the plurality of components of the encoding device 100 shown in FIG. 1 are implemented by the processor a1 and the memory a2 shown in FIG. 40.
- the processor a1 is a circuit that performs information processing and is a circuit that can access the memory a2.
- the processor a1 is a dedicated or general-purpose electronic circuit that encodes a moving image.
- the processor a1 may be a processor such as a CPU.
- the processor a1 may be an aggregate of a plurality of electronic circuits. Further, for example, the processor a1 may play the role of a plurality of components among the plurality of components of the coding device 100 shown in FIG. 1 and the like.
- the memory a2 is a dedicated or general-purpose memory in which information for the processor a1 to encode a moving image is stored.
- the memory a2 may be an electronic circuit or may be connected to the processor a1. Further, the memory a2 may be included in the processor a1. Further, the memory a2 may be an aggregate of a plurality of electronic circuits. Further, the memory a2 may be a magnetic disk, an optical disk, or the like, or may be expressed as a storage, a recording medium, or the like. Further, the memory a2 may be a non-volatile memory or a volatile memory.
- the encoded moving image may be stored in the memory a2, or the bit string corresponding to the encoded moving image may be stored.
- the memory a2 may store a program for the processor a1 to encode a moving image.
- the memory a2 may serve as a component for storing information among the plurality of components of the encoding device 100 shown in FIG.
- the memory a2 may serve as the block memory 118 and the frame memory 122 shown in FIG. More specifically, the reconstructed block, the reconstructed picture, and the like may be stored in the memory a2.
- not all of the plurality of components shown in FIG. 1 and the like may be mounted, or all of the plurality of processes described above may not be performed.
- a part of the plurality of constituent elements illustrated in FIG. 1 and the like may be included in another device, and a part of the plurality of processes described above may be executed by another device.
- FIG. 41 is a block diagram showing a functional configuration of the decoding device 200 according to the embodiment.
- the decoding device 200 is a moving image decoding device that decodes moving images in block units.
- the decoding device 200 includes an entropy decoding unit 202, an inverse quantization unit 204, an inverse transformation unit 206, an addition unit 208, a block memory 210, a loop filter unit 212, and a frame memory 214. And an intra prediction unit 216, an inter prediction unit 218, and a prediction control unit 220.
- the decoding device 200 is realized by, for example, a general-purpose processor and a memory.
- the processor uses the entropy decoding unit 202, the inverse quantization unit 204, the inverse conversion unit 206, the addition unit 208, the loop filter unit 212, and the intra prediction unit. It functions as 216, an inter-prediction unit 218, and a prediction control unit 220.
- the decoding device 200 is dedicated to the entropy decoding unit 202, the inverse quantization unit 204, the inverse conversion unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220. It may be realized as one or more electronic circuits of.
- FIG. 42 is a flowchart showing an example of the overall decoding process by the decoding device 200.
- the entropy decoding unit 202 of the decoding device 200 specifies a division pattern of a fixed size block (for example, 128 ⁇ 128 pixels) (step Sp_1).
- This division pattern is a division pattern selected by the coding apparatus 100.
- the decoding device 200 performs the processes of steps Sp_2 to Sp_6 for each of the plurality of blocks constituting the division pattern.
- the entropy decoding unit 202 decodes (specifically, entropy decoding) the encoded quantized coefficient and the prediction parameter of the decoding target block (also referred to as the current block) (step Sp_2).
- the inverse quantization unit 204 and the inverse conversion unit 206 restore a plurality of predicted residuals (that is, difference blocks) by performing inverse quantization and inverse conversion on a plurality of quantization coefficients (step Sp_3). ).
- the prediction processing unit including all or part of the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220 generates a prediction signal (also referred to as a prediction block) of the current block (step Sp_4).
- the addition unit 208 reconstructs the current block into a reconstructed image (also referred to as a decoded image block) by adding the prediction block to the difference block (step Sp_5).
- the loop filter unit 212 filters the reconstructed image (step Sp_6).
- step Sp_7 determines whether or not the decoding of the entire picture is completed (step Sp_7), and if it is determined that the decoding is not completed (No in step Sp_7), the processing from step Sp_1 is repeatedly executed.
- steps Sp_1 to Sp_7 are sequentially performed by the decoding device 200. Alternatively, some of these processes may be performed in parallel, or the order may be changed.
- the entropy decoding unit 202 entropy decodes the coded bit stream. Specifically, the entropy decoding unit 202 arithmetically decodes a coded bitstream into a binary signal, for example. Then, the entropy decoding unit 202 multivalues the binary signal. The entropy decoding unit 202 outputs the quantized coefficient in block units to the inverse quantization unit 204. The entropy decoding unit 202 may output the prediction parameters included in the coded bit stream (see FIG. 1) to the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220 in the embodiment. The intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220 can execute the same prediction processing as the processing performed by the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128 on the encoding device side.
- the inverse quantization unit 204 inversely quantizes the quantized coefficient of the decoding target block (hereinafter referred to as the current block) that is the input from the entropy decoding unit 202. Specifically, the inverse quantization unit 204 inversely quantizes each quantized coefficient of the current block based on the quantized parameter corresponding to the quantized coefficient. Then, the inverse quantization unit 204 outputs the inverse quantization coefficient (that is, the conversion coefficient) of the current block to the inverse conversion unit 206.
- the inverse transform unit 206 restores the prediction error by inversely transforming the transform coefficient that is the input from the inverse quantization unit 204.
- the inverse transformation unit 206 determines the current block based on the information denoting the deciphered transformation type. Invert the transformation coefficient of.
- the inverse transform unit 206 applies inverse retransform to the transform coefficient.
- the addition unit 208 reconstructs the current block by adding the prediction error input from the inverse conversion unit 206 and the prediction sample input from the prediction control unit 220. Then, the addition unit 208 outputs the reconstructed block to the block memory 210 and the loop filter unit 212.
- the block memory 210 is a storage unit that stores a block that is referred to in intra prediction and that is included in a decoding target picture (hereinafter referred to as a current picture). Specifically, the block memory 210 stores the reconstructed block output from the addition unit 208.
- the loop filter unit 212 applies a loop filter to the block reconstructed by the addition unit 208, and outputs the filtered reconstructed block to the frame memory 214, the display device, and the like.
- one filter is selected from among the filters based on the direction of the local gradient and the activity. The selected filter is applied to the reconstructed block.
- the frame memory 214 is a storage unit for storing a reference picture used for inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 214 stores the reconstructed block filtered by the loop filter unit 212.
- FIG. 43 is a flowchart showing an example of processing performed by the prediction processing unit of the decoding device 200.
- the prediction processing unit includes all or a part of the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220.
- the prediction processing unit generates a prediction image of the current block (step Sq_1).
- This prediction image is also referred to as a prediction signal or a prediction block.
- the prediction signal includes, for example, an intra prediction signal or an inter prediction signal.
- the prediction processing unit generates a prediction block, a difference block, a coefficient block, a difference block, and a decoded image block, and reconstructs an already obtained reconstructed image. Is used to generate a predicted image of the current block.
- the reconstructed image may be, for example, an image of a reference picture or an image of a decoded block in the current picture which is a picture including the current block.
- the decoded block in the current picture is, for example, a block adjacent to the current block.
- FIG. 44 is a flowchart showing another example of the processing performed by the prediction processing unit of the decoding device 200.
- the prediction processing unit determines the method or mode for generating the prediction image (step Sr_1). For example, this method or mode may be determined based on, for example, prediction parameters.
- the prediction processing unit determines the first method as the mode for generating the prediction image
- the prediction processing unit generates the prediction image according to the first method (step Sr_2a).
- the prediction processing unit determines the second method as the mode for generating the prediction image
- the prediction processing unit generates the prediction image according to the second method (step Sr_2b).
- the prediction processing unit determines the third method as the mode for generating the prediction image
- the prediction processing unit generates the prediction image according to the third method (step Sr_2c).
- the first method, the second method, and the third method are different methods for generating a prediction image, and are, for example, an inter prediction method, an intra prediction method, and other prediction methods, respectively. It may be. In these prediction methods, the above-mentioned reconstructed image may be used.
- the intra prediction unit 216 performs intra prediction by referring to a block in the current picture stored in the block memory 210 based on the intra prediction mode read from the coded bit stream, thereby performing a prediction signal (intra prediction). Signal). Specifically, the intra prediction unit 216 generates an intra prediction signal by performing intra prediction with reference to a sample of a block adjacent to the current block (for example, a luminance value and a color difference value), and predicts and controls the intra prediction signal. Output to the section 220.
- the intra prediction unit 216 may predict the color difference component of the current block based on the brightness component of the current block. ..
- the intra prediction unit 216 corrects the pixel value after intra prediction based on the gradient of reference pixels in the horizontal/vertical directions.
- the inter-prediction unit 218 predicts the current block by referring to the reference picture stored in the frame memory 214. Prediction is made in units of the current block or sub-blocks within the current block (eg, 4x4 blocks). For example, the inter prediction unit 218 performs motion compensation using motion information (for example, a motion vector) that has been deciphered from a coded bitstream (for example, a prediction parameter output from the entropy decoding unit 202), or the current block or The sub-block inter-prediction signal is generated, and the inter-prediction signal is output to the prediction control unit 220.
- motion information for example, a motion vector
- a coded bitstream for example, a prediction parameter output from the entropy decoding unit 202
- the inter-prediction unit 218 uses not only the motion information of the current block obtained by the motion search but also the motion information of the adjacent block. , Generates an inter-prediction signal.
- the inter-prediction unit 218 follows the pattern matching method (bilateral matching or template matching) read from the coded stream. Motion information is derived by performing motion search. Then, the inter-prediction unit 218 performs motion compensation (prediction) using the derived motion information.
- the inter-prediction unit 218 derives a motion vector based on a model assuming constant velocity linear motion when the BIO mode is applied. In addition, when the information read from the encoded bitstream indicates that the affine motion compensation prediction mode is applied, the inter prediction unit 218 determines the motion vector in subblock units based on the motion vectors of a plurality of adjacent blocks. Derive.
- the inter-prediction unit 218 derives the MV based on the information read from the coded stream and uses the MV. Motion compensation (prediction) is performed.
- FIG. 45 is a flowchart showing an example of inter-prediction by the normal inter-mode in the decoding device 200.
- the inter-prediction unit 218 of the decoding device 200 performs motion compensation for each block.
- the inter-prediction unit 218 acquires a plurality of candidate MVs for the current block based on information such as MVs of the plurality of decoded blocks around the current block temporally or spatially (step Ss_1). That is, the inter prediction unit 218 creates a candidate MV list.
- the inter-prediction unit 218 selects each of N (N is an integer of 2 or more) candidate MVs from the plurality of candidate MVs acquired in step Ss_1 as predictive motion vector candidates (also referred to as predicted MV candidates). As a result, extraction is performed according to a predetermined priority (step Ss_2). The priority may be predetermined for each of the N predicted MV candidates.
- the inter prediction unit 218 decodes the motion vector predictor selection information from the input stream (that is, the encoded bit stream), and uses the decoded motion vector predictor selection information, the N prediction MV candidates.
- One predicted MV candidate is selected as a predicted motion vector (also referred to as predicted MV) of the current block (step Ss_3).
- the inter-prediction unit 218 decodes the difference MV from the input stream, and adds the difference value, which is the decoded difference MV, to the selected predicted motion vector to obtain the MV of the current block. Derivation (step Ss_4).
- the inter-prediction unit 218 generates a prediction image of the current block by performing motion compensation for the current block using the derived MV and the decoded reference picture (step Ss_5).
- the prediction control unit 220 selects either an intra prediction signal or an inter prediction signal, and outputs the selected signal to the addition unit 208 as a prediction signal.
- the configurations, functions, and processes of the predictor control unit 220, the intra prediction unit 216, and the inter prediction unit 218 on the decoding device side are the prediction control unit 128, the intra prediction unit 124, and the inter prediction unit 126 on the encoding device side. It may correspond to the configuration, function, and processing of.
- FIG. 46 is a block diagram showing an implementation example of the decoding device 200.
- the decoding device 200 includes a processor b1 and a memory b2.
- the plurality of components of the decoding device 200 shown in FIG. 41 are implemented by the processor b1 and the memory b2 shown in FIG.
- the processor b1 is a circuit that performs information processing and is a circuit that can access the memory b2.
- the processor b1 is a dedicated or general-purpose electronic circuit that decodes an encoded moving image (that is, an encoded bit stream).
- the processor b1 may be a processor such as a CPU.
- the processor b1 may be an aggregate of a plurality of electronic circuits. Further, for example, the processor b1 may play the role of a plurality of components among the plurality of components of the decoding device 200 shown in FIG. 41 and the like.
- the memory b2 is a dedicated or general-purpose memory in which information for the processor b1 to decode the encoded bitstream is stored.
- the memory b2 may be an electronic circuit or may be connected to the processor b1. Further, the memory b2 may be included in the processor b1. Further, the memory b2 may be an aggregate of a plurality of electronic circuits.
- the memory b2 may be a magnetic disk, an optical disk, or the like, and may be expressed as a storage, a recording medium, or the like. Further, the memory b2 may be a non-volatile memory or a volatile memory.
- the memory b2 may store a moving image or an encoded bitstream. Further, the memory b2 may store a program for the processor b1 to decode the coded bit stream.
- the memory b2 may play the role of a component for storing information among the plurality of components of the decoding device 200 shown in FIG. 41 and the like. Specifically, the memory b2 may play the role of the block memory 210 and the frame memory 214 shown in FIG. More specifically, the reconstructed block, the reconstructed picture, and the like may be stored in the memory b2.
- the decoding device 200 not all of the plurality of constituent elements shown in FIG. 41 or the like may be implemented, or all of the plurality of processes described above may not be performed. Some of the plurality of components shown in FIG. 41 and the like may be included in another device, and some of the plurality of processes described above may be executed by another device.
- each term may be defined as follows.
- the picture is an array of multiple luminance samples in a monochrome format, or an array of multiple luminance samples and a plurality of color difference samples in the 4: 2: 0, 4: 2: 2 and 4: 4: 4 color formats. It is a corresponding array.
- the picture may be a frame or a field.
- the frame is a composition of a top field in which a plurality of sample rows 0, 2, 4, ... Are generated, and a bottom field composition in which a plurality of sample rows 1, 3, 5, ... Are generated.
- a slice is an integer coded tree contained in one independent slice segment and all subsequent dependent slice segments that precede the next independent slice segment (if any) in the same access unit (if any). It is a unit.
- a tile is a rectangular area of multiple coded tree blocks within a particular tile column and a particular tile row in a picture.
- the tile may still be a loop filter across the edges of the tile, but may be a rectangular area of the frame intended to be independently decoded and encoded.
- the block is an MxN (N rows and M columns) array of a plurality of samples, or an MxN array of a plurality of conversion coefficients.
- the block may be a square or rectangular area of a plurality of pixels consisting of a plurality of matrices of one luminance and two color differences.
- the CTU may be a coded tree block of a plurality of luminance samples of a picture having three sample arrays, or may be two corresponding coded tree blocks of a plurality of color difference samples. ..
- the CTU is a coding tree block of any of a plurality of samples, a monochrome picture and a picture encoded using three separate color planes and a syntax structure used for encoding the plurality of samples. It may be.
- the super block may be a square block of 64 ⁇ 64 pixels that constitutes one or two mode information blocks, or is recursively divided into four 32 ⁇ 32 blocks and can be further divided.
- IBC Intra Block Copy
- the IBC mode may be used as one mode of normal inter-prediction, and may be used together with, for example, a merge mode, a normal inter-mode, a skip mode, and the like. Hereinafter, the IBC mode will be described more specifically with reference to the drawings.
- FIG. 47 is a diagram for explaining the IBC (intra block copy) mode.
- FIG. 47 (a) is a diagram showing an example of a region that can be referred to in the IBC mode.
- FIG. 47 (b) is a diagram showing an example of a block vector.
- the inter-prediction unit 126 refers to an already encoded and decoded block in a picture different from the current block in the inter-prediction processing of the current block (hereinafter, also referred to as a processing target block), but the inter-prediction processing using the IBC mode is used. Then, as in the intra prediction process, only the pixels already encoded and decoded in the same picture as the current block are referred to. For example, as shown in FIG. 47 (a), the pixels that can be referred to in the screen are the pixels located on the upper side or the left side of the current block. The area including these pixels is called a referenceable area.
- the encoding device 100 may determine a vector indicating the displacement of the position of the current block and the reference block in order to identify the reference block in the same frame or picture as the current block (that is, in the screen). ..
- This vector is called a block vector (BV).
- the block vector contains, for example, an x component and a y component
- the x component (BVx) indicates, for example, the horizontal displacement between the current block and the reference block.
- the y component (BVy) indicates the vertical displacement between the current block and the reference block.
- the origin of the BV may be the pixel position in the upper left corner of the current block.
- the BV is a vector connecting the upper left corner of the current block and the upper left corner of the reference block.
- the coding device 100 signals the BV into the coded bitstream so that the decoding device 200 can identify the reference block selected by the coding device 100 when decoding the coded bitstream. ..
- the coding device 100 and the decoding device 200 according to the first aspect generate a predicted image of the processing target block (hereinafter, also referred to as a processing target CU) using the first motion vector, and the first candidate having the first motion vector.
- HMVP History based Motion
- HMVP History based Motion
- a processed block hereinafter, also referred to as a processed CU
- FIFO First In First Out
- the coding device 100 and the decoding device 200 generate a candidate MVP list including a plurality of predicted motion vector candidates (hereinafter, also referred to as candidate motion vectors or candidate MVPs), and are included in the generated candidate MVP list.
- the first motion vector is encoded using one of a plurality of predicted motion vector candidates, and when the size of the block to be processed is less than or equal to the threshold size in the generation of the candidate MVP list, the use of the HMVP table is prohibited. If the size of the block to be processed is larger than the threshold size, the use of the HMVP table is permitted.
- the processed block is a coded block in the coding process and a decoded block in the decoding process.
- the coding device 100 will be described below.
- the inter-prediction unit 126 of the coding apparatus 100 sets the processing target block based on information such as a plurality of coded blocks located around the processing target block temporally or spatially.
- a plurality of candidate motion vectors (hereinafter, also referred to as candidate prediction motion vectors (candidate MVP)) are acquired.
- the inter-prediction unit 126 of the processing target block is based on a plurality of prediction candidates having motion vectors (hereinafter, also referred to as MV information) of the plurality of encoded blocks and reference picture information corresponding to the motion vectors.
- a prediction candidate list (hereinafter, also referred to as a candidate MVP list) including a combination of a motion vector candidate and reference picture information corresponding to the motion vector candidate as a prediction candidate is created.
- the inter-prediction unit 126 selects a prediction candidate from the FIFO buffer for the HMVP mode (hereinafter, also referred to as an HMVP table) and registers it in the prediction candidate list.
- FIG. 48 is a diagram for explaining the HMVP mode.
- the candidate MVP list in the figure may be a prediction candidate list for the merge mode or a prediction candidate list for the AMVP mode (hereinafter, referred to as an AMVP candidate list).
- the numbers after MVP and HMVP in the figure indicate the order of registration in the list and the buffer.
- one candidate MVP is selected from the candidate MVP list generated by referring to the processed block (processed CU) to be processed (processed target).
- the motion vector (MV) of CU) is determined.
- the coding device 100 selects one candidate MVP from the AMVP candidate list and calculates the difference between the MV of the processing target CU and the candidate MVP.
- the difference and the index of the candidate MVP are encoded.
- the encoding device 100 when the encoding device 100 generates a predicted image of a block to be processed in the merge mode, the encoding device 100 selects one merge index from the merge candidate MVP list, and the candidate associated with the merge index is selected. Select the MVP and the reference picture index. The encoding device 100 encodes the selected merge mode index.
- the candidate MVP list includes a spatially adjacent predicted motion vector (also referred to as a spatially adjacent MVP or a spatially predicted MV candidate), which is a motion vector possessed by a plurality of encoded CUs located in the spatial periphery of the CU to be processed.
- a time-adjacent predicted motion vector (also referred to as a time-adjacent MVP or a time-predicted MV candidate), which is a motion vector possessed by a CU in the vicinity of projecting the position of the processing target CU in the encoded reference picture, is registered.
- a candidate MVP of the HMVP mode As one of the candidate MVPs to be registered in this candidate MVP list, there is a candidate MVP of the HMVP mode.
- the candidate MVP is managed by using the FIFO buffer for the HMVP separately from the candidate MVP list of the merge mode and the AMVP mode.
- a predetermined number of prediction candidates (so-called candidate MVPs) having MV information of CUs processed in the past (that is, CUs processed before the CU to be processed) from the newest to the CU processing order Only (for example, five in FIG. 48) are stored.
- candidate MVPs prediction candidates having MV information of CUs processed in the past
- Only for example, five in FIG. 48
- each time the coding device 100 processes one CU it has a prediction having MV information of the newest CU (in other words, the CU processed immediately before the CU).
- the coding device 100 may store the prediction candidate having the MV information of the CU in the FIFO buffer each time the processing of one CU is completed.
- the encoding device 100 when the coding device 100 stores the prediction candidate having new MV information in the FIFO buffer, the encoding device 100 has the MV information of the oldest CU (in other words, the first processed CU) in the FIFO buffer. Remove the candidate from the buffer. As a result, the coding apparatus 100 can manage the prediction candidates in the FIFO buffer in the latest state.
- HMVP1 in the FIFO buffer is a prediction candidate having the MV information of the latest CU
- HMVP5 in the FIFO buffer is a prediction candidate having the MV information of the oldest CU.
- the prediction candidates having the same MV information as any of the MV information of the plurality of prediction candidates (so-called candidate MVP) stored in the FIFO buffer for the HMVP mode are the prediction candidate list for the merge mode and the AMVP mode. If it is not registered in (candidate MVP list in the figure), the prediction candidate having the MV information stored in the FIFO buffer for the HMVP mode is registered in the prediction candidate list.
- the encoding device 100 has MV information different from the MV information of all the prediction candidates already registered in the candidate MVP list for a plurality of prediction candidates in the FIFO buffer. Search for the presence or absence. More specifically, the encoding device 100 puts the prediction candidates in the FIFO buffer into the candidate MVP list for the merge mode and the AMVP mode in order from the prediction candidate having the MV information of the latest CU (here, HMVP1). It is determined whether or not the prediction candidate has MV information different from all the prediction candidates (so-called candidate MVP) already registered.
- the encoding device 100 adds the HMVP1 to the candidate MVP list. Then, the coding apparatus 100 performs the same processing for each of the HMVP2 to HMVP5.
- the number of prediction candidates for the HMVP mode registered in the candidate MVP list may be one or a plurality.
- the coding apparatus 100 can select a more suitable candidate MVP for the processing target CU, so that the coding efficiency is improved.
- the MV information may include not only the MV value but also information such as information on the picture to be referred to, the direction to be referred to, and the number of pictures to be referred to.
- the candidate MVP list and FIFO buffer shown in FIG. 48 is an example, and may be a list and buffer having a size different from that shown in the drawing, or may be configured to register candidate MVPs in an order different from the drawing. ..
- the coding device 100 has been described as an example here, the above processing is common to the coding device 100 and the decoding device 200.
- FIG. 49 is a flowchart 1000 showing an example of the operations performed by the coding device 100 and the decoding device 200 in the first aspect of the present disclosure.
- the candidate MVP list is a candidate MVP list in AMVP mode (that is, an AMVP candidate list).
- the coding device 100 starts loop processing in units of CU in the prediction processing of the picture to be processed (not shown). First, the coding apparatus 100 determines the size of the processing target CU (that is, the processing target block) (step S1001). Next, the coding apparatus 100 determines whether or not the size of the block to be processed is equal to or less than the threshold size (for example, 16 pixels) (step S1002).
- the threshold size is, for example, the threshold of the number of pixels in the processing target block, and the threshold size is, for example, 16 pixels.
- the threshold size is not limited to 16 pixels and may be another value. Further, for example, when the size of the processing target block is defined by the width or height of the processing target block, the threshold size may be 4 pixels.
- the coding apparatus 100 When the coding device 100 determines that the size of the block to be processed is not equal to or less than the threshold size (16 pixels in this case) (No in step S1003), the coding apparatus 100 generates an AMVP candidate list using the HMVP table (step S1004). .. In other words, the encoding device 100 permits the use of the HMVP table when the size of the processing target block is determined to be larger than the threshold size in the generation of the AMVP candidate list.
- FIG. 50 is a flowchart showing an example of a process of generating an AMVP candidate list using the HMVP table.
- the coding apparatus 100 uses the normal intermode in generating the predicted image of the block to be processed.
- the coding device 100 adds the spatial prediction MV candidate to the AMVP candidate list (step S1101).
- the encoding device 100 and the decoding device 200 determine whether or not there is a vacancy in the AMVP candidate list (step S1102), and if it is determined that there is no vacancy in the AMVP candidate list (No in step S1102), the AMVP The process of generating the candidate list ends.
- the encoding device 100 determines that there is a vacancy in the AMVP candidate list (Yes in step S1102), the encoding device 100 adds the time prediction MV candidate to the AMVP candidate list (step S1103).
- the encoding device 100 determines whether or not there is a vacancy in the AMVP candidate list (step S1104), and when it is determined that there is no vacancy in the AMVP candidate list (No in step S1104), the AMVP candidate list generation process. To finish. On the other hand, when the encoding device 100 determines that the AMVP candidate list is empty (Yes in step S1104), the encoding device 100 adds the HMVP candidate to the AMVP candidate list (step S1105).
- the encoding device 100 determines whether or not there is a vacancy in the AMVP candidate list (step S1106), and when it is determined that there is no vacancy in the AMVP candidate list (No in step S1106), the AMVP candidate list generation process. To finish. On the other hand, when the encoding device 100 determines that the AMVP candidate list is empty (Yes in step S1106), the coding apparatus 100 adds the zero prediction MV candidate to the AMVP candidate list (step S1107).
- the number of candidate MVPs added to the AMVP list may be one or plural.
- step S1107 when the zero prediction MV candidate is added to the AMVP candidate list and it is determined that there is no space in the AMVP candidate list, the AMVP candidate list generation process is terminated.
- FIG. 51 is a flowchart showing another example of the process of generating the AMVP candidate list using the HMVP table.
- the coding apparatus 100 uses the IBC mode in generating the predicted image of the block to be processed.
- steps S1103 and S1104 are not performed. That is, the example of FIG. 51 is different from the example of FIG. 50 in that the time prediction MV candidate is not added to the AMVP candidate list.
- the coding apparatus 100 determines that the size of the block to be processed is equal to or less than the threshold size (here, 16 pixels) (Yes in step S1003), the HVMP table is not used. Generate an AMVP candidate list (step S1005).
- the encoding device 100 permits the use of the HMVP table when it is determined that the size of the processing target block is equal to or less than the threshold size in the generation of the AMVP candidate list.
- FIG. 52 is a flowchart showing an example of a process of generating an AMVP candidate list without using the HMVP table.
- the coding apparatus 100 uses the normal intermode in generating the predicted image of the block to be processed.
- step S1105 and step S1106 are not performed. That is, the example of FIG. 52 differs from the example of FIG. 50 in that HMVP is not added to the AMVP candidate list.
- FIG. 53 is a flowchart showing another example of the process of generating the AMVP candidate list without using the HMVP table.
- the coding apparatus 100 uses the IBC mode in generating the predicted image of the block to be processed.
- steps S1103 and S1104 are not performed. That is, the example of FIG. 53 differs from the example of FIG. 52 in that the time prediction MV candidate is not added to the AMVP candidate list.
- the coding apparatus 100 encodes the processing target block using the AMVP candidate list generated in step S1004 and step S1005 (step S1006).
- the coding device 100 repeats the processes of S1001 to S1006 for all the CUs in the picture to be processed, and then ends the loop process for each CU (not shown).
- the coding device 100 has been described as an example here, the above processing is common to the coding device 100 and the decoding device 200.
- the encoding device 100 determines whether or not the HMVP table can be used depending on whether or not the size of the processing target block is equal to or less than the threshold size.
- the same determination process may be performed in the generation of the candidate MVP list (merge candidate MVP list) in the merge mode.
- the coding apparatus 100 uses the HMVP table to generate a merge candidate MVP list.
- the merge candidate MVP list the candidate MVP and the information of the reference picture (reference picture index) are associated and registered.
- the first aspect of the present disclosure introduces a constraint on the size of the block to be processed in the generation of the AMVP candidate list using the HMVP table.
- the coding device 100 and the decoding device 200 can generate the AMVP candidate list without using the HMVP table when the size of the processing target block is equal to or less than the threshold size.
- the encoding device 100 and the decoding device 200 may skip the process of comparing the candidate MVP stored in the HMVP table with the candidate MVP registered in the AMVP candidate list in the generation of the AMVP candidate list. it can. Therefore, according to the coding device 100 and the decoding device 200 according to the first aspect of the present disclosure, the processing amount is reduced, so that the coding efficiency of the coding device 100 and the processing efficiency of the decoding device 200 are improved.
- the number of cycles for generating the AMVP candidate list using the HMVP table may be reduced. As a result, the processing amount of the coding device 100 and the decoding device 200 is reduced.
- the generation of the AMVP candidate list in the AMVP mode has been described, but similarly, in the generation of the candidate MVP list (merge candidate MVP list) in the merge mode, a restriction depending on the size of the block to be processed is introduced. You may.
- the coding device 100 and the decoding device 200 can generate a candidate MVP list without using the HMVP table when the size of the block to be processed is equal to or less than the threshold size, so that the processing amount is reduced.
- the coding device 100, the decoding device 200, the coding method, and the decoding method according to the second aspect will be described.
- the AMVP candidate list generation process has been described, but in the second aspect, the HMVP table update process will be described.
- the coding device 100 and the decoding device 200 according to the first aspect according to the second aspect generate a predicted image of the processing target block (that is, the processing target CU) using the first motion vector, and have the first motion vector.
- the HMVP table that stores a plurality of second candidates having the second motion vector used in the processed block (that is, the processed CU) in the FIFO method is updated, and the HMVP table is updated.
- the first candidate has the first reference picture information corresponding to the first motion vector
- each of the plurality of second candidates has the second reference picture information corresponding to the second motion vector.
- FIG. 54 is a flowchart 2000 showing an example of the operations performed by the coding device 100 and the decoding device 200 in the second aspect of the present disclosure.
- the coding device 100 will be described.
- the coding device 100 starts loop processing in units of CU in the prediction processing of the picture to be processed (not shown).
- the coding apparatus 100 uses the reference motion vector from the AMVP candidate list to determine the motion vector (so-called first motion vector) of the block to be processed (step S2001).
- the coding apparatus 100 determines whether or not the size of the block to be processed is equal to or less than the threshold size (for example, 16 pixels) (step S2002).
- the threshold size is, for example, the threshold of the number of pixels in the block to be processed, and the threshold size is, for example, 16 pixels.
- the threshold size is not limited to 16 pixels, and may be another value or threshold. There may be.
- the threshold size may be 4 pixels.
- the coding device 100 uses the motion vector of the processing target block (so-called first motion vector). Then, the HMVP table is updated (step S2004).
- the first candidate a set of the first motion vector and the first reference picture information
- the second candidates a set of the second motion vector and the second reference picture information
- the coding apparatus 100 may update the HMVP table by storing the first candidate in the HMVP table. Further, the coding apparatus 100 may discard the first candidate when the first candidate matches any of the plurality of second candidates.
- the HMVP table is updated, including the process of discarding the first candidate.
- the encoding device 100 determines that the size of the block to be processed is equal to or less than the threshold size (here, 16 pixels or less) (Yes in step S2003), the coding apparatus 100 does not update the HVMP table (step S2005). That is, the coding device 100 skips the update process of the HMVPBookUp table (HMVP FIFO buffer of FIG. 48). As described in step S2004, since the update process includes the above-mentioned determination process, the determination process is also skipped here.
- the coding device 100 encodes the processing target block after the update processing of the HMVP table shown in step S2004 and step S2005 (step S2006).
- step S2006 the example in which the processes of step S2002, step S2003, step S2004, and step S2005 are performed before step S2006 has been described here, for example, it may be after step S2006, or the next block to be processed. If it is before the coding, it may be performed at any other timing. For example, the processes of step S2004 and step S2005 may be performed in parallel.
- the coding device 100 repeats the processes of steps S2001 to S2006 for all the CUs in the picture to be processed, and then ends the loop process for each CU (not shown).
- the coding device 100 has been described as an example here, the above processing is common to the coding device 100 and the decoding device 200.
- the encoding device 100 determines whether or not the HMVP table can be updated depending on whether or not the size of the processing target block is equal to or less than the threshold size.
- the HMVP table is used to generate a candidate MVP list depending on whether or not the size of the block to be processed is equal to or less than the threshold size in both the AMVP mode and the merge mode. Therefore, the above HMVP update process may be performed in the same manner in both the AMVP mode and the merge mode.
- the second aspect of the present disclosure introduces a constraint on the size of the block to be processed in updating the HMVP table.
- the number of cycles may be reduced when the size of the block to be processed is small (for example, when it is equal to or less than the threshold size).
- One or more aspects disclosed herein may be implemented in combination with at least a portion of the other aspects of the present disclosure.
- a part of the processing described in the flowchart of one or more aspects disclosed here a part of the configuration of the device, a part of the syntax, and the like may be performed in combination with the other aspects.
- the HMVP table update processing according to the size of the processing target block described in the second aspect is applied, and the IBC mode is applied.
- the HMVP table update process may be applied regardless of the size of the block to be processed. In this case, the HMVP table is not updated when the IBC mode is used and the size of the block to be processed is 16 pixels or less, and the HMVP table is updated otherwise.
- the device / method may include some of the processes / elements.
- the above processing may be executed by the decoding device as well as the coding device.
- FIG. 55 is a flowchart showing the operation performed by the coding device 100.
- the coding device 100 includes a circuit and a memory connected to the circuit.
- the circuit and memory included in the coding device 100 may correspond to the processor a1 and the memory a2 shown in FIG. 40.
- the circuit of the coding device 100 does the following:
- the circuit of the coding apparatus 100 generates a predicted image of the block to be processed using the first motion vector (step S3001), and uses the first candidate having the first motion vector in the processed block.
- the HMVP table that stores a plurality of second candidates having the obtained second motion vector in the FIFO method is updated (step S3002), and in the update of the HMVP table, whether or not the size of the block to be processed is equal to or less than the threshold size is determined. If it is determined (step S30021) and it is determined that the size of the block to be processed is equal to or less than the threshold size (Yes in step S30021), the update of the HMVP table is skipped (step S30022).
- the coding device 100 updates the HMVP table when the size of the block to be processed is larger than the threshold size, so that the processing amount is reduced. Therefore, the coding device 100 has improved coding efficiency.
- the circuit of the coding apparatus 100 further generates a candidate MVP list including a plurality of predicted motion vector candidates, and uses one of the plurality of predicted motion vector candidates included in the generated candidate MVP list.
- the use of the HMVP table is prohibited when the size of the processing target block is smaller than the threshold size, and when the size of the processing target block is larger than the threshold size, the HMVP table is used. You may allow the use of.
- the coding device 100 generates a candidate list without using the HMVP table when the size of the processing target block is equal to or less than the threshold value, so that the processing amount is reduced. Therefore, the coding device 100 has improved coding efficiency.
- the size of the processing target block may be defined by the number of pixels in the processing target block.
- the threshold size may be 16 pixels.
- the coding apparatus 100 skips the update of the HMVP table or generates the candidate list without using the HVMP table, so that the processing amount is large. It will be reduced. Therefore, the coding device 100 has improved coding efficiency.
- the size of the processing target block may be defined by the width or height of the processing target block.
- the encoding device 100 skips updating the HMVP table or uses the HMVP table when, for example, the width or height of the size of the block to be processed is equal to or less than the threshold size (for example, 4 pixels or less). Since the candidate list is generated without this, the processing amount is reduced. Therefore, the coding device 100 has improved coding efficiency.
- the circuit of the coding device 100 may use an intermode that refers to a coded picture different from the picture to which the processing target block belongs in generating the predicted image of the processing target block.
- the coding apparatus 100 acquires a plurality of predicted motion vector candidates for the processing target block based on information such as a plurality of coded blocks located around the processing target block temporally or spatially. Then, the prediction processing of the processing target block can be performed.
- the circuit of the coding device 100 may use the IBC mode that refers to the encoded region of the picture to which the processing target block belongs in generating the predicted image of the processing target block.
- the coding device 100 can specify and read the reference block based on the motion vector indicating the already encoded and decoded reference block in the same picture as the processing target block.
- the first candidate has the first reference picture information corresponding to the first motion vector
- each of the plurality of second candidates has the second reference picture information corresponding to the second motion vector and is encoded.
- the circuit of the device 100 determines whether or not the first candidate matches any of the plurality of second candidates, and when the first candidate does not match any of the plurality of second candidates.
- the HMVP table may be updated by storing the first candidate in the HMVP table (step S30023).
- the coding device 100 expands the range of variations of the first candidate stored in the HMVP table, so that more appropriate prediction candidates for the processing target block can be registered in the candidate list.
- the candidate MVP list may be a candidate MVP list in the AMVP (Adaptive Motion Vector Precision) mode.
- AMVP Adaptive Motion Vector Precision
- the coding device 100 can register the candidate MVP of the HMVP mode in the candidate MVP list in the AMVP mode, so that the prediction accuracy is improved.
- the candidate MVP list may be a candidate MVP list in the merge mode.
- the encoding device 100 can register the candidate MVP of the HMVP mode in the candidate MVP list in the merge mode, so that the prediction accuracy is improved.
- FIG. 56 is a flowchart showing the operation performed by the decoding device 200.
- the decoding device 200 includes a circuit and a memory connected to the circuit.
- the circuit and memory included in the decoding device 200 may correspond to the processor b1 and the memory b2 shown in FIG.
- the circuit of the decoding device 200 performs the following in operation.
- the circuit of the decoding device 200 generates a predicted image of the block to be processed using the first motion vector (step S4001), and is used in the processed block by using the first candidate having the first motion vector.
- the HMVP table that stores a plurality of second candidates having the second motion vector in the FIFO method is updated (step S4002), and in the update of the HMVP table, it is determined whether or not the size of the block to be processed is equal to or less than the threshold size. If it is determined that the size of the block to be processed is equal to or less than the threshold size (Yes in step S40021), the update of the HMVP table is skipped (step S40022).
- the decoding device 200 updates the HMVP table when the size of the block to be processed is larger than the threshold size, so that the amount of processing is reduced. Therefore, the decoding device 200 is improved in processing efficiency.
- the circuit of the decoding device 200 further generates a candidate MVP list including a plurality of predicted motion vector candidates, and uses one of the plurality of predicted motion vector candidates included in the generated candidate MVP list. 1
- the use of the HMVP table is prohibited.
- the HMVP table You may allow the use.
- the decoding device 200 generates a candidate MVP list without using the HMVP table when the size of the block to be processed is equal to or less than the threshold value, so that the processing amount is reduced. Therefore, the decoding device 200 is improved in processing efficiency.
- the size of the processing target block may be defined by the number of pixels in the processing target block.
- the threshold size may be 16 pixels.
- the decoding device 200 skips the update of the HMVP table or generates the candidate MVP list without using the HVMP table, so that the processing amount is large. It will be reduced. Therefore, the decoding device 200 is improved in processing efficiency.
- the size of the processing target block may be defined by the width or height of the processing target block.
- the decoding device 200 skips updating the HMVP table or does not use the HMVP table when, for example, the width or height of the size of the block to be processed is equal to or less than the threshold size (for example, 4 pixels or less). Since the candidate MVP list is generated in the above, the processing amount is reduced. Therefore, the decoding device 200 is improved in processing efficiency.
- the circuit of the decoding device 200 may use an intermode that refers to a coded picture different from the picture to which the processing target block belongs in generating the predicted image of the processing target block.
- the decoding device 200 acquires a plurality of predicted motion vector candidates for the processing target block based on information such as a plurality of encoded blocks located around the processing target block temporally or spatially. Therefore, the prediction processing of the processing target block can be performed.
- the circuit of the decoding device 200 may use the IBC mode that refers to the encoded region of the picture to which the processing target block belongs in generating the predicted image of the processing target block.
- the decoding device 200 can specify and read the reference block based on the motion vector indicating the already decoded and encoded reference block in the same picture as the processing target block.
- the first candidate has the first reference picture information corresponding to the first motion vector
- each of the plurality of second candidates has the second reference picture information corresponding to the second motion vector and is encoded.
- the circuit of the device 100 determines whether or not the first candidate matches any of the plurality of second candidates, and when the first candidate does not match any of the plurality of second candidates.
- the HMVP table may be updated by storing the first candidate in the HMVP table (step S40023).
- the decoding device 200 expands the range of variations of the first candidate stored in the HMVP table, so that more appropriate prediction candidates for the processing target block can be registered in the candidate MVP list.
- the candidate MVP list may be a candidate MVP list in the AMVP mode.
- the decoding device 200 can register the candidate MVP of the HMVP mode in the candidate MVP list in the AMVP mode, so that the prediction accuracy is improved.
- the candidate MVP list may be a candidate MVP list in the merge mode.
- the decoding device 200 can register the candidate MVP of the HMVP mode in the candidate MVP list in the merge mode, so that the prediction accuracy is improved.
- each component may be a circuit as described above. These circuits may constitute one circuit as a whole or may be separate circuits. Each component may be realized by a general-purpose processor or a dedicated processor.
- the encoding/decoding device may include the encoding device 100 and the decoding device 200.
- the aspects of the coding device 100 and the decoding device 200 have been described above based on a plurality of examples, the aspects of the coding device 100 and the decoding device 200 are not limited to these examples. As long as the gist of the present disclosure is not deviated, various modifications that can be conceived by those skilled in the art are applied to each example, and a form constructed by combining components in different examples is also within the scope of the aspects of the coding device 100 and the decoding device 200. May be included within.
- One or more aspects disclosed herein may be implemented in combination with at least a portion of the other aspects of the present disclosure. Further, a part of the processing described in the flowchart of one or more aspects disclosed here, a part of the configuration of the apparatus, a part of the syntax, and the like may be performed in combination with the other aspects.
- the device / method may include some of the processes / elements. Further, the above processing may be executed by a decoding device as well as a coding device.
- the inter-prediction unit 216 of the coding device 100 and the inter-prediction unit 218 of the decoding device 200 perform prediction processing using the IBC mode when the processing target picture, which is a picture including the processing target block, is used as a reference picture.
- prediction processing may be performed using the normal intermode.
- each of the functional or active blocks can usually be realized by an MPU (micro processing unit), a memory, or the like. Further, the processing by each of the functional blocks may be realized as a program execution unit such as a processor that reads out and executes software (program) recorded in a recording medium such as a ROM. The software may be distributed. The software may be recorded on various recording media such as semiconductor memory. It is also possible to realize each functional block by hardware (dedicated circuit). Various combinations of hardware and software can be adopted.
- each embodiment may be realized by centralized processing using a single device (system), or may be realized by distributed processing using a plurality of devices. Further, the number of processors that execute the above program may be singular or plural. That is, centralized processing may be performed or distributed processing may be performed.
- an application example of the moving image coding method (image coding method) or the moving image decoding method (image decoding method) shown in each of the above embodiments, and various systems for implementing the application example are provided.
- Such a system may be characterized by having an image coding device using an image coding method, an image decoding device using an image decoding method, or an image coding / decoding device including both. Other configurations of such a system can be appropriately changed depending on the case.
- FIG. 57 is a diagram showing an overall configuration of an appropriate content supply system ex100 that realizes a content distribution service.
- the communication service providing area is divided into desired sizes, and base stations ex106, ex107, ex108, ex109, and ex110, which are fixed radio stations in the illustrated example, are installed in each cell, respectively.
- devices such as a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, and a smartphone ex115 are connected to the Internet ex101 via the Internet service provider ex102 or the communication network ex104, and the base stations ex106 to ex110. Is connected.
- the content supply system ex100 may be connected by combining any of the above devices.
- the devices may be directly or indirectly connected to each other via a telephone network, short-range radio, or the like, without going through base stations ex106 to ex110.
- the streaming server ex103 may be connected to each device such as a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, and a smartphone ex115 via the Internet ex101 or the like. Further, the streaming server ex103 may be connected to a terminal or the like in a hotspot in the airplane ex117 via the satellite ex116.
- the streaming server ex103 may be directly connected to the communication network ex104 without going through the Internet ex101 or the Internet service provider ex102, or may be directly connected to the airplane ex117 without going through the satellite ex116.
- the camera ex113 is a device such as a digital camera capable of shooting still images and moving images.
- the smartphone ex115 is a smartphone device, a mobile phone, a PHS (Personal Handy-phone System), or the like that supports a mobile communication system called 2G, 3G, 3.9G, 4G, and 5G in the future.
- a mobile communication system called 2G, 3G, 3.9G, 4G, and 5G in the future.
- the home appliance ex114 is a refrigerator or a device included in a household fuel cell cogeneration system.
- live distribution or the like becomes possible by connecting a terminal having a shooting function to the streaming server ex103 through a base station ex106 or the like.
- terminals computer ex111, game machine ex112, camera ex113, home appliances ex114, smartphone ex115, terminals in airplane ex117, etc.
- the coding process described in each embodiment may be performed, or the video data obtained by coding may be multiplexed with the sound data in which the sound corresponding to the video is encoded, and the obtained data is streamed. It may be transmitted to the server ex103. That is, each terminal functions as an image coding device according to one aspect of the present disclosure.
- the streaming server ex103 streams the content data transmitted to the requested client.
- the client is a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, a smartphone ex115, a terminal in an airplane ex117, or the like, which can decode the coded data.
- Each device that has received the distributed data may decrypt the received data and reproduce it. That is, each device may function as an image decoding device according to one aspect of the present disclosure.
- the streaming server ex103 may be a plurality of servers or a plurality of computers, and may disperse data for processing, recording, and distribution.
- the streaming server ex103 may be realized by a CDN (Contents Delivery Network), and content distribution may be realized by a network connecting a large number of edge servers distributed all over the world.
- CDN Contents Delivery Network
- content distribution may be realized by a network connecting a large number of edge servers distributed all over the world.
- physically close edge servers can be dynamically assigned depending on the client. Then, the delay can be reduced by caching and delivering the content to the edge server.
- processing is distributed among multiple edge servers, the distribution entity is switched to another edge server, or a failure occurs. Since distribution can be continued by bypassing the network part, high-speed and stable distribution can be realized.
- the coding processing of the captured data may be performed on each terminal, on the server side, or shared with each other.
- the processing loop is performed twice.
- the first loop the complexity or code amount of the image on a frame or scene basis is detected.
- the second loop a process of maintaining the image quality and improving the coding efficiency is performed.
- the terminal performs the first coding process
- the server side that receives the content performs the second coding process, so that the quality and efficiency of the content can be improved while reducing the processing load on each terminal. it can.
- the first encoded data performed by the terminal can be received and played back by another terminal, enabling more flexible real-time distribution.
- the camera ex113 or the like extracts a feature amount (feature or characteristic amount) from the image, compresses the data related to the feature amount as metadata, and transmits the data to the server.
- the server performs compression according to the meaning of the image (or the importance of the content), for example, determining the importance of the object from the feature amount and switching the quantization accuracy.
- the feature data is particularly effective for improving the accuracy and efficiency of motion vector prediction during recompression on the server.
- the terminal may perform simple coding such as VLC (variable length coding), and the server may perform coding having a large processing load such as CABAC (context adaptive binary arithmetic coding method).
- a plurality of video data in which almost the same scene is shot by a plurality of terminals.
- GOP Group of Pictures
- the server may manage and / or instruct so that the video data shot by each terminal can be referred to each other. Further, the encoded data from each terminal may be received by the server and the reference relationship may be changed between the plurality of data, or the picture itself may be corrected or replaced and re-encoded. This makes it possible to generate a stream with improved quality and efficiency of each piece of data.
- the server may distribute the video data after transcoding to change the coding method of the video data.
- the server may convert the MPEG type encoding method to the VP type (for example, VP9), or the H.264 standard. 264 is H. It may be converted to 265 or the like.
- the encoding process can be performed by the terminal or one or more servers. Therefore, in the following, the description of "server” or “terminal” or the like is used as the subject of processing, but a part or all of the processing performed by the server may be performed by the terminal, or the processing performed by the terminal. Some or all may be done on the server. The same applies to the decoding process.
- the server not only encodes the two-dimensional moving image, but also automatically encodes the still image based on the scene analysis of the moving image or at the time specified by the user, and transmits the still image to the receiving terminal. May be good. If the server can acquire the relative positional relationship between the shooting terminals, the server can obtain the three-dimensional shape of the scene based not only on the two-dimensional moving image but also on the images of the same scene shot from different angles. Can be generated.
- the server may separately encode the three-dimensional data generated by the point cloud or the like, or may generate a plurality of images to be transmitted to the receiving terminal based on the result of recognizing or tracking a person or an object using the three-dimensional data. It may be generated by selecting or reconstructing from the video taken by the terminal of.
- the user can arbitrarily select each image corresponding to each shooting terminal and enjoy the scene, or can select the image of the selected viewpoint from the plurality of images or the three-dimensional data reconstructed using the images. You can also enjoy the cut out content. Furthermore, along with the video, the sound is also picked up from multiple different angles, and the server may multiplex the sound from a particular angle or space with the corresponding video and transmit the multiplexed video and sound. Good.
- the server may create viewpoint images for the right eye and the left eye, respectively, and perform coding that allows reference between the viewpoint images by Multi-View Coding (MVC) or the like, or mutually. It may be encoded as a separate stream without reference. At the time of decoding another stream, it is preferable to reproduce them in synchronization with each other so that a virtual three-dimensional space is reproduced according to the viewpoint of the user.
- MVC Multi-View Coding
- the server may superimpose the virtual object information on the virtual space on the camera information in the real space based on the three-dimensional position or the movement of the user's viewpoint.
- the decoding device may acquire or hold virtual object information and three-dimensional data, generate a two-dimensional image according to the movement of the user's viewpoint, and create superimposed data by smoothly connecting the images.
- the decoding device may transmit the movement of the user's viewpoint to the server in addition to the request for the virtual object information.
- the server may create superimposed data according to the movement of the viewpoint received from the three-dimensional data held in the server, encode the superimposed data, and distribute the superimposed data to the decoding device.
- the superimposed data typically has an ⁇ value indicating transparency other than RGB
- the server sets the ⁇ value of the part other than the object created from the three-dimensional data to 0 or the like, and the relevant part. May be encoded while being transparent.
- the server may set RGB values having a predetermined value as a background like a chroma key, and may generate data in which a portion other than the object has a background color.
- the RGB value of the predetermined value may be predetermined.
- the decryption process of the distributed data may be performed by the client (for example, the terminal), the server side, or the processes may be shared by each other.
- a terminal may once send a reception request to a server, the content corresponding to the request may be received by another terminal, decryption processing may be performed, and the decoded signal may be transmitted to a device having a display. It is possible to reproduce high-quality data by distributing the processing and selecting an appropriate content regardless of the performance of the terminal capable of communication.
- a part of an area such as a tile in which a picture is divided may be decoded and displayed on the viewer's personal terminal. As a result, while sharing the whole picture, it is possible to confirm the field of responsibility or the area to be confirmed in more detail at hand.
- the user may switch in real time while freely selecting a decoding device or a display device such as a user's terminal or a display arranged indoors or outdoors.
- a decoding device or a display device such as a user's terminal or a display arranged indoors or outdoors.
- access to the coded data on the network such as the coded data being cached in a server that can be accessed from the receiving terminal in a short time, or being copied to an edge server in the content delivery service. It is also possible to switch the bit rate of the received data based on ease.
- the content switching will be described using a scalable stream compressed and encoded by applying the moving image coding method shown in each of the above embodiments shown in FIG. 58.
- the server may have multiple streams with the same content but different qualities as individual streams, but it is temporally / spatially scalable, which is realized by encoding by dividing into layers as shown in the figure.
- a configuration may be used in which contents are switched by utilizing the characteristics of streams.
- the decoding side determines which layer to decode according to the internal factor of performance and the external factor such as the state of the communication band, and the decoding side determines the low resolution content and the high resolution content. It can be freely switched and decrypted.
- the device may decode the same stream to different layers, so that the server.
- the burden on the side can be reduced.
- the picture is encoded for each layer, and in addition to the configuration that realizes scalability in the enhancement layer above the base layer, the enhancement layer includes meta information based on the statistical information of the image and the like. Good.
- the decoding side may generate high-quality content by super-resolution of the base layer picture based on the meta information. Super-resolution may improve the signal-to-noise ratio while maintaining and / or expanding the resolution.
- the meta information is information for specifying a linear or non-linear filter coefficient such as that used for super-resolution processing, or information for specifying a parameter value in filter processing, machine learning, or minimum square calculation used for super-resolution processing. including.
- a configuration may be provided in which the picture is divided into tiles or the like according to the meaning of objects in the image.
- the decoding side decodes only a part of the area by selecting the tile to be decoded. Furthermore, by storing the object attributes (person, car, ball, etc.) and the position in the image (coordinate position in the same image, etc.) as meta information, the decoding side can determine the position of the desired object based on the meta information. To determine the tile that contains the object. For example, as shown in FIG. 59, the meta information may be stored using a data storage structure different from the pixel data, such as an SEI (supplemental enhancement information) message in HEVC. This meta information indicates, for example, the position, size, or color of the main object.
- SEI Supplemental Enhancement Information
- -Meta information may be stored in units composed of multiple pictures, such as streams, sequences, or random access units.
- the decoding side can acquire the time when a specific person appears in the video, can identify the picture in which the object exists, and can determine the position of the object in the picture by combining the information for each picture and the time information.
- FIG. 60 is a diagram showing an example of a display screen of a web page on a computer ex111 or the like.
- FIG. 61 is a diagram showing an example of a display screen of a web page on a smartphone ex115 or the like.
- a web page may include a plurality of linked images that are links to image contents, and the appearance may differ depending on the viewing device. If multiple linked images are visible on the screen, the display device (until the user explicitly selects the linked image, or until the linked image approaches the center of the screen or the entire linked image fits inside the screen.
- the decoding device may display a still image or I-picture of each content as a link image, may display an image such as a gif animation with a plurality of still images or I-pictures, or may display a base layer. Only may be received and the video may be decoded and displayed.
- the display device When the link image is selected by the user, the display device performs decoding while giving the highest priority to, for example, the base layer. If the HTML constituting the web page has information indicating that the content is scalable, the display device may decode up to the enhancement layer. Further, in order to ensure real-time performance, the display device decodes only the forward reference picture (I picture, P picture, B picture of forward reference only) before being selected or when the communication band is very strict. By displaying and, the delay between the decoding time of the first picture and the display time (delay from the decoding start of the content to the display start) can be reduced. Furthermore, the display device may deliberately ignore the reference relationship of the pictures, roughly decode all the B pictures and the P pictures as forward references, and perform normal decoding as the number of received pictures increases over time. ..
- the receiving terminal receives meta in addition to image data belonging to one or more layers.
- Information such as weather or construction may be received as information, and these may be associated and decoded.
- the meta information may belong to the layer or may be simply multiplexed with the image data.
- the receiving terminal since a car, a drone, an airplane, etc. including the receiving terminal moves, the receiving terminal transmits the position information of the receiving terminal to perform seamless reception and decoding while switching the base stations ex106 to ex110. realizable.
- the receiving terminal dynamically switches how much meta information is received or how much map information is updated according to the user's selection, the user's situation, and / or the state of the communication band. Becomes possible.
- the client can receive, decode, and reproduce the encoded information transmitted by the user in real time.
- the server may perform the editing process and then the encoding process. This can be realized by using the following configuration, for example.
- the server After shooting in real time or accumulating at the time of shooting, the server performs recognition processing such as shooting error, scene search, meaning analysis, and object detection from the original image data or encoded data. Then, the server manually or automatically corrects out-of-focus or camera shake based on the recognition result, and reduces the importance of scenes such as scenes with low brightness or out of focus compared to other pictures. Make edits such as deleting, emphasizing the edges of objects, and changing the tint. The server encodes the edited data based on the edited result. It is also known that if the shooting time is too long, the audience rating will drop, and the server will move not only the less important scenes as described above so that the content will be within a specific time range according to the shooting time. A scene with a small number of images may be automatically clipped based on the image processing result. Alternatively, the server may generate and encode a digest based on the results of the semantic analysis of the scene.
- recognition processing such as shooting error, scene search, meaning analysis, and object detection from the original image data or encode
- the server may intentionally change the face of a person in the peripheral portion of the screen, the inside of the house, or the like into an image that is out of focus and encode it. Furthermore, the server recognizes whether or not the face of a person different from the person registered in advance is reflected in the image to be encoded, and if so, performs processing such as applying a mosaic to the face part. You may.
- a person or background area in which the user wants to process an image may be specified from the viewpoint of copyright or the like.
- the server may perform processing such as replacing the designated area with another video or defocusing. If it is a person, the person in the moving image can be tracked to replace the image of the face portion of the person.
- the decoding device may first receive the base layer with the highest priority for decoding and playback, although it depends on the bandwidth.
- the decoding device may receive the enhancement layer during this period and reproduce the high-quality video including the enhancement layer when the enhancement layer is received and the reproduction is performed twice or more, such as when the reproduction is looped.
- a stream with such scalable encoding can provide an experience in which the stream gradually becomes smarter and the image becomes better, although it is a rough moving image when it is not selected or when it is first started to be viewed.
- a similar experience can be provided even if the coarse stream played the first time and the second stream encoded with reference to the first video are configured as one stream. ..
- these encoding or decoding processes are generally processed in the LSI ex500 included in each terminal.
- the LSI (large scale integration circuit) ex500 may be one-chip or a plurality of chips.
- software for video coding or decoding is embedded in some recording medium (CD-ROM, flexible disk, hard disk, etc.) that can be read by a computer ex111 or the like, and encoding or decoding processing is performed using the software. Good.
- the smartphone ex115 has a camera, the moving image data acquired by the camera may be transmitted. The moving image data at this time may be data encoded by the LSI ex500 included in the smartphone ex115.
- the LSIex500 may be configured to download and activate the application software.
- the terminal first determines whether the terminal is compatible with the content encoding method or has the ability to execute a specific service. If the terminal does not support the content encoding method, or if it does not have the ability to execute a specific service, the terminal may download the codec or application software, and then acquire and play the content.
- the digital broadcasting system has at least a moving image coding device (image coding device) or a moving image decoding device (image decoding device) of each of the above embodiments. Any of the above can be incorporated.
- the difference is that it is suitable for multicast compared to the configuration that makes it easy to unicast the content supply system ex100 because it transmits and receives multiplexed data in which video and sound are multiplexed on radio waves for broadcasting using satellites and the like.
- similar applications can be applied to the coding process and the decoding process.
- FIG. 62 is a diagram showing further details of the smartphone ex115 shown in FIG. 57. Further, FIG. 63 is a diagram showing a configuration example of the smartphone ex115.
- the smartphone ex115 received the antenna ex450 for transmitting and receiving radio waves to and from the base station ex110, the camera unit ex465 capable of taking images and still images, the image captured by the camera unit ex465, and the antenna ex450. It is provided with a display unit ex458 that displays the data obtained by decoding the video or the like.
- the smartphone ex115 further includes an operation unit ex466 such as a touch panel, a voice output unit ex457 such as a speaker for outputting voice or sound, and a voice input unit ex456 such as a microphone for inputting voice.
- the user is specified as a memory unit ex467 that can store encoded data such as recorded video or still image, recorded voice, received video or still image, mail, or decoded data, and the network is started. It is provided with a slot unit ex464 which is an interface unit with SIMex468 for authenticating access to various data. An external memory may be used instead of the memory unit ex467.
- Main control unit ex460 that can comprehensively control display unit ex458, operation unit ex466, etc., power supply circuit unit ex461, operation input control unit ex462, video signal processing unit ex455, camera interface unit ex463, display control unit ex459, modulation / The demodulation unit ex452, the multiplexing / separation unit ex453, the audio signal processing unit ex454, the slot unit ex464, and the memory unit ex467 are connected via the synchronization bus ex470.
- the power supply circuit unit ex461 activates the smartphone ex115 in an operable state and supplies power to each unit from the battery pack.
- the smartphone ex115 performs processing such as call and data communication under the control of the main control unit ex460 including a CPU, a ROM, a RAM, and the like.
- the audio signal picked up by the audio input unit ex456 is converted into a digital audio signal by the audio signal processing unit ex454, spectrum diffusion processing is performed by the modulation / demodulation unit ex452, and digital-analog conversion processing is performed by the transmission / reception unit ex451. And frequency conversion processing is performed, and the resulting signal is transmitted via the antenna ex450.
- the received data is amplified, subjected to frequency conversion processing and analog-to-digital conversion processing, spectrum reverse diffusion processing is performed by the modulation / demodulation unit ex452, converted into an analog audio signal by the audio signal processing unit ex454, and then converted into an analog audio signal, which is then converted to an analog audio signal.
- text, still image, or video data can be transmitted under the control of the main control unit ex460 via the operation input control unit ex462 based on the operation of the operation unit ex466 of the main body unit. Similar transmission / reception processing is performed.
- the video signal processing unit ex455 uses the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 to perform each of the above operations.
- the moving picture coding method shown in the form is used for compression coding, and the coded video data is sent to the multiplexing/demultiplexing unit ex453.
- the audio signal processing unit ex454 encodes the audio signal picked up by the audio input unit ex456 while the video or still image is being imaged by the camera unit ex465, and sends the encoded audio data to the multiplexing / separation unit ex453.
- the multiplexing/demultiplexing unit ex453 multiplexes the coded video data and the coded audio data by a predetermined method, and the modulation/demodulation unit (modulation/demodulation circuit unit) ex452 and the transmission/reception unit ex451 perform modulation processing and conversion. It is processed and transmitted via the antenna ex450.
- the predetermined method may be predetermined.
- the multiplexing / separating unit ex453 is multiplexed.
- the multiplexed data is divided into a bit stream of video data and a bit stream of audio data, and the video data encoded via the synchronization bus ex470 is supplied to the video signal processing unit ex455, and at the same time.
- the encoded audio data is supplied to the audio signal processing unit ex454.
- the video signal processing unit ex455 decodes the video signal by the moving image decoding method corresponding to the moving image coding method shown in each of the above embodiments, and is linked from the display unit ex458 via the display control unit ex459.
- the video or still image included in the moving image file is displayed.
- the audio signal processing unit ex454 decodes the audio signal, and the audio output unit ex457 outputs the audio.
- audio playback may not be socially appropriate depending on the user's situation. Therefore, as an initial value, it is preferable to play back only the video data without playing the audio signal, and the audio may be played back in synchronization only when the user clicks the video data or performs an operation. ..
- the smartphone ex115 has been described as an example here, as the terminal, in addition to the transmission / reception type terminal having both the encoder and the decoder, the transmitting terminal having only the encoder and the receiving terminal having only the decoder.
- Another possible implementation is a terminal. It has been described as receiving or transmitting multiplexed data in which audio data is multiplexed with video data in a digital broadcasting system.
- character data related to the video may be multiplexed as the multiplexed data.
- the video data itself may be received or transmitted instead of the multiplexed data.
- the main control unit ex460 including the CPU has been described as controlling the encoding or decoding process, but various terminals often include a GPU. Therefore, a memory shared by the CPU and the GPU, or a memory whose address is managed so that it can be used in common, may be configured to collectively process a wide area by utilizing the performance of the GPU. As a result, the coding time can be shortened, real-time performance can be ensured, and low delay can be realized. In particular, it is efficient to collectively perform motion search, deblocking filter, SAO (Sample Adaptive Offset), and conversion / quantization processing in units such as pictures on the GPU instead of the CPU.
- SAO Sample Adaptive Offset
- the present disclosure can be used, for example, in television receivers, digital video recorders, car navigation systems, mobile phones, digital cameras, digital video cameras, video conferencing systems, electronic mirrors, and the like.
- Encoding device 102 Dividing unit 104 Subtracting unit 106 Converting unit 108 Quantizing unit 110 Entropy encoding unit 112, 204 Inverse quantization unit 114, 206 Inverse conversion unit 116, 208 Addition unit 118, 210 Block memory 120, 212 Loop filter Unit 122, 214 Frame memory 124, 216 Intra prediction unit 126, 218 Inter prediction unit 128, 220 Prediction control unit 200
- Decoding device 202 Entropy decoding unit 1201 Boundary determination unit 1202, 1204, 1206 Switch 1203 Filter determination unit 1205 Filter processing unit 1207 Filter characteristic determination unit 1208 Processing determination unit a1, b1 Processor a2, b2 Memory
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Abstract
Description
まず、実施の形態に係る符号化装置を説明する。図1は、実施の形態に係る符号化装置100の機能構成を示すブロック図である。符号化装置100は、動画像をブロック単位で符号化する動画像符号化装置である。
図2は、符号化装置100による全体的な符号化処理の一例を示すフローチャートである。
分割部102は、入力動画像に含まれる各ピクチャを複数のブロックに分割し、各ブロックを減算部104に出力する。例えば、分割部102は、まず、ピクチャを固定サイズ(例えば128x128)のブロックに分割する。他の固定ブロックサイズが採用されてもよい。この固定サイズのブロックは、符号化ツリーユニット(CTU)と呼ばれることがある。そして、分割部102は、例えば再帰的な四分木(quadtree)及び/又は二分木(binary tree)ブロック分割に基づいて、固定サイズのブロックの各々を可変サイズ(例えば64x64以下)のブロックに分割する。すなわち、分割部102は、分割パターンを選択する。この可変サイズのブロックは、符号化ユニット(CU)、予測ユニット(PU)あるいは変換ユニット(TU)と呼ばれることがある。なお、種々の処理例では、CU、PU及びTUは区別される必要はなく、ピクチャ内の一部又はすべてのブロックがCU、PU、TUの処理単位となってもよい。
ピクチャを並列にデコードするために、ピクチャはスライス単位またはタイル単位で構成される場合がある。スライス単位またはタイル単位からなるピクチャは、分割部102によって構成されてもよい。
減算部104は、分割部102から入力され、分割部102によって分割されたブロック単位で、原信号(原サンプル)から予測信号(以下に示す予測制御部128から入力される予測サンプル)を減算する。つまり、減算部104は、符号化対象ブロック(以下、カレントブロックという)の予測誤差(残差ともいう)を算出する。そして、減算部104は、算出された予測誤差(残差)を変換部106に出力する。
変換部106は、空間領域の予測誤差を周波数領域の変換係数に変換し、変換係数を量子化部108に出力する。具体的には、変換部106は、例えば空間領域の予測誤差に対して所定の離散コサイン変換(DCT)又は離散サイン変換(DST)を行う。所定のDCT又はDSTは、予め定められていてもよい。
量子化部108は、変換部106から出力された変換係数を量子化する。具体的には、量子化部108は、カレントブロックの変換係数を所定の走査順序で走査し、走査された変換係数に対応する量子化パラメータ(QP)に基づいて当該変換係数を量子化する。そして、量子化部108は、カレントブロックの量子化された変換係数(以下、量子化係数という)をエントロピー符号化部110及び逆量子化部112に出力する。所定の走査順序は、予め定められていてもよい。
エントロピー符号化部110は、量子化部108から入力された量子化係数に基づいて符号化信号(符号化ビットストリーム)を生成する。具体的には、エントロピー符号化部110は、例えば、量子化係数を二値化し、二値信号を算術符号化し、圧縮されたビットストリームまたはシーケンスを出力する。
逆量子化部112は、量子化部108から入力された量子化係数を逆量子化する。具体的には、逆量子化部112は、カレントブロックの量子化係数を所定の走査順序で逆量子化する。そして、逆量子化部112は、カレントブロックの逆量子化された変換係数を逆変換部114に出力する。所定の走査順序は、予め定められていてもよい。
逆変換部114は、逆量子化部112から入力された変換係数を逆変換することにより予測誤差(残差)を復元する。具体的には、逆変換部114は、変換係数に対して、変換部106による変換に対応する逆変換を行うことにより、カレントブロックの予測誤差を復元する。そして、逆変換部114は、復元された予測誤差を加算部116に出力する。
加算部116は、逆変換部114から入力された予測誤差と予測制御部128から入力された予測サンプルとを加算することによりカレントブロックを再構成する。そして、加算部116は、再構成されたブロックをブロックメモリ118及びループフィルタ部120に出力する。再構成ブロックは、ローカル復号ブロックと呼ばれることもある。
ブロックメモリ118は、例えば、イントラ予測で参照されるブロックであって符号化対象ピクチャ(カレントピクチャという)内のブロックを格納するための記憶部である。具体的には、ブロックメモリ118は、加算部116から出力された再構成ブロックを格納する。
フレームメモリ122は、例えば、インター予測に用いられる参照ピクチャを格納するための記憶部であり、フレームバッファと呼ばれることもある。具体的には、フレームメモリ122は、ループフィルタ部120によってフィルタされた再構成ブロックを格納する。
ループフィルタ部120は、加算部116によって再構成されたブロックにループフィルタを施し、フィルタされた再構成ブロックをフレームメモリ122に出力する。ループフィルタとは、符号化ループ内で用いられるフィルタ(インループフィルタ)であり、例えば、デブロッキング・フィルタ(DFまたはDBF)、サンプルアダプティブオフセット(SAO)及びアダプティブループフィルタ(ALF)などを含む。
デブロッキング・フィルタでは、ループフィルタ部120は、再構成画像のブロック境界にフィルタ処理を行うことによって、そのブロック境界に生じる歪みを減少させる。
q’1=(p0+q0+q1+q2+2)/4
q’2=(p0+q0+q1+3×q2+2×q3+4)/8
図11は、符号化装置100の予測処理部で行われる処理の一例を示すフローチャートである。なお、予測処理部は、イントラ予測部124、インター予測部126、および予測制御部128の全てまたは一部の構成要素からなる。
イントラ予測部124は、ブロックメモリ118に格納されたカレントピクチャ内のブロックを参照してカレントブロックのイントラ予測(画面内予測ともいう)を行うことで、予測信号(イントラ予測信号)を生成する。具体的には、イントラ予測部124は、カレントブロックに隣接するブロックのサンプル(例えば輝度値、色差値)を参照してイントラ予測を行うことでイントラ予測信号を生成し、イントラ予測信号を予測制御部128に出力する。
インター予測部126は、フレームメモリ122に格納された参照ピクチャであってカレントピクチャとは異なる参照ピクチャを参照してカレントブロックのインター予測(画面間予測ともいう)を行うことで、予測信号(インター予測信号)を生成する。インター予測は、カレントブロック又はカレントブロック内のカレントサブブロック(例えば4x4ブロック)の単位で行われる。例えば、インター予測部126は、カレントブロック又はカレントサブブロックについて参照ピクチャ内で動き探索(motion estimation)を行い、そのカレントブロック又はカレントサブブロックに最も一致する参照ブロック又はサブブロックを見つける。そして、インター予測部126は、参照ブロック又はサブブロックからカレントブロック又はサブブロックへの動き又は変化を補償する動き情報(例えば動きベクトル)を取得する。インター予測部126は、その動き情報に基づいて、動き補償(または動き予測)を行い、カレントブロック又はサブブロックのインター予測信号を生成する。インター予測部126は、生成されたインター予測信号を予測制御部128に出力する。
図15は、インター予測の基本的な流れの一例を示すフローチャートである。
図16は、動きベクトル導出の一例を示すフローチャートである。
図18は、動きベクトル導出の他の例を示すフローチャートである。MV導出のモード、すなわちインター予測モードには、複数のモードがあり、大きく分けて、差分MVを符号化するモードと、差分動きベクトルを符号化しないモードとがある。差分MVを符号化しないモードには、マージモード、FRUCモード、およびアフィンモード(具体的には、アフィンマージモード)がある。これらのモードの詳細については、後述するが、簡単には、マージモードは、周辺の符号化済みブロックから動きベクトルを選択することによって、カレントブロックのMVを導出するモードであり、FRUCモードは、符号化済み領域間で探索を行うことによって、カレントブロックのMVを導出するモードである。また、アフィンモードは、アフィン変換を想定して、カレントブロックを構成する複数のサブブロックそれぞれの動きベクトルを、カレントブロックのMVとして導出するモードである。
ノーマルインターモードは、候補MVによって示される参照ピクチャの領域から、カレントブロックの画像に類似するブロックに基づいて、カレントブロックのMVを導出するインター予測モードである。また、このノーマルインターモードでは、差分MVが符号化される。
マージモードは、候補MVリストから候補MVをカレントブロックのMVとして選択することによって、そのMVを導出するインター予測モードである。
動き情報は符号化装置側から信号化されずに、復号装置側で導出されてもよい。なお、上述のように、H.265/HEVC規格で規定されたマージモードが用いられてもよい。また例えば、復号装置側で動き探索を行うことにより動き情報が導出されてもよい。実施の形態において、復号装置側では、カレントブロックの画素値を用いずに動き探索が行われる。
第1パターンマッチングでは、異なる2つの参照ピクチャ内の2つのブロックであってカレントブロックの動き軌道(motion trajectory)に沿う2つのブロックの間でパターンマッチングが行われる。したがって、第1パターンマッチングでは、上述した候補の評価値の算出のための所定の領域として、カレントブロックの動き軌道に沿う他の参照ピクチャ内の領域が用いられる。所定の領域は、予め定められていてもよい。
第2パターンマッチング(テンプレートマッチング)では、カレントピクチャ内のテンプレート(カレントピクチャ内でカレントブロックに隣接するブロック(例えば上及び/又は左隣接ブロック))と参照ピクチャ内のブロックとの間でパターンマッチングが行われる。したがって、第2パターンマッチングでは、上述した候補の評価値の算出のための所定の領域として、カレントピクチャ内のカレントブロックに隣接するブロックが用いられる。
次に、複数の隣接ブロックの動きベクトルに基づいてサブブロック単位で動きベクトルを導出するアフィンモードについて説明する。このモードは、アフィン動き補償予測(affine motion compensation prediction)モードと呼ばれることがある。
図25Bは、3つの制御ポイントを有するアフィンモードにおけるサブブロック単位の動きベクトルの導出の一例を説明するための概念図である。図25Bにおいて、カレントブロックは、16の4x4サブブロックを含む。ここでは、隣接ブロックの動きベクトルに基づいてカレントブロックの左上角制御ポイントの動きベクトルv0が導出され、同様に、隣接ブロックの動きベクトルに基づいてカレントブロックの右上角制御ポイントの動きベクトルv1、隣接ブロックの動きベクトルに基づいてカレントブロックの左下角制御ポイントの動きベクトルv2が導出される。そして、以下の式(1B)により、3つの動きベクトルv0、v1及びv2が投影されてもよく、カレントブロック内の各サブブロックの動きベクトル(vx,vy)が導出されてもよい。
図26A、図26Bおよび図26Cは、アフィンマージモードを説明するための概念図である。
図28Aは、2つの制御ポイントを有するアフィンインターモードを説明するための概念図である。
異なる制御ポイント数(例えば、2つと3つ)のアフィンモードをCUレベルで切り替えて信号化する場合、符号化済みブロックとカレントブロックで制御ポイントの数が異なる場合がある。図30Aおよび図30Bは、符号化済みブロックとカレントブロックで制御ポイントの数が異なる場合の、制御ポイントの予測ベクトル導出方法を説明するための概念図である。
図31Aは、マージモードおよびDMVRの関係を示すフローチャートである。
動き補償では、予測画像を生成し、その予測画像を補正するモードがある。そのモードは、例えば、後述のBIOおよびOBMCである。
動き探索により得られたカレントブロックの動き情報だけでなく、隣接ブロックの動き情報も用いて、インター予測信号が生成されてもよい。具体的には、(参照ピクチャ内の)動き探索により得られた動き情報に基づく予測信号と、(カレントピクチャ内の)隣接ブロックの動き情報に基づく予測信号と、を重み付け加算することにより、カレントブロック内のサブブロック単位でインター予測信号が生成されてもよい。このようなインター予測(動き補償)は、OBMC(overlapped block motion compensation)と呼ばれることがある。
次に、動きベクトルを導出する方法について説明する。まず、等速直線運動を仮定したモデルに基づいて動きベクトルを導出するモードについて説明する。このモードは、BIO(bi-directional optical flow)モードと呼ばれることがある。
次に、LIC(local illumination compensation)処理を用いて予測画像(予測)を生成するモードの一例について説明する。
予測制御部128は、イントラ予測信号(イントラ予測部124から出力される信号)及びインター予測信号(インター予測部126から出力される信号)のいずれかを選択し、選択した信号を予測信号として減算部104及び加算部116に出力する。
図40は、符号化装置100の実装例を示すブロック図である。符号化装置100は、プロセッサa1及びメモリa2を備える。例えば、図1に示された符号化装置100の複数の構成要素は、図40に示されたプロセッサa1及びメモリa2によって実装される。
次に、例えば上記の符号化装置100から出力された符号化信号(符号化ビットストリーム)を復号可能な復号装置について説明する。図41は、実施の形態に係る復号装置200の機能構成を示すブロック図である。復号装置200は、動画像をブロック単位で復号する動画像復号装置である。
図42は、復号装置200による全体的な復号処理の一例を示すフローチャートである。
エントロピー復号部202は、符号化ビットストリームをエントロピー復号する。具体的には、エントロピー復号部202は、例えば、符号化ビットストリームから二値信号に算術復号する。そして、エントロピー復号部202は、二値信号を多値化(debinarize)する。エントロピー復号部202は、ブロック単位で量子化係数を逆量子化部204に出力する。エントロピー復号部202は、実施の形態におけるイントラ予測部216、インター予測部218および予測制御部220に、符号化ビットストリーム(図1参照)に含まれている予測パラメータを出力してもよい。イントラ予測部216、インター予測部218および予測制御部220は、符号化装置側におけるイントラ予測部124、インター予測部126および予測制御部128で行われる処理と同じ予測処理を実行することができる。
逆量子化部204は、エントロピー復号部202からの入力である復号対象ブロック(以下、カレントブロックという)の量子化係数を逆量子化する。具体的には、逆量子化部204は、カレントブロックの量子化係数の各々について、当該量子化係数に対応する量子化パラメータに基づいて当該量子化係数を逆量子化する。そして、逆量子化部204は、カレントブロックの逆量子化された量子化係数(つまり変換係数)を逆変換部206に出力する。
逆変換部206は、逆量子化部204からの入力である変換係数を逆変換することにより予測誤差を復元する。
加算部208は、逆変換部206からの入力である予測誤差と予測制御部220からの入力である予測サンプルとを加算することによりカレントブロックを再構成する。そして、加算部208は、再構成されたブロックをブロックメモリ210及びループフィルタ部212に出力する。
ブロックメモリ210は、イントラ予測で参照されるブロックであって復号対象ピクチャ(以下、カレントピクチャという)内のブロックを格納するための記憶部である。具体的には、ブロックメモリ210は、加算部208から出力された再構成ブロックを格納する。
ループフィルタ部212は、加算部208によって再構成されたブロックにループフィルタを施し、フィルタされた再構成ブロックをフレームメモリ214及び表示装置等に出力する。
フレームメモリ214は、インター予測に用いられる参照ピクチャを格納するための記憶部であり、フレームバッファと呼ばれることもある。具体的には、フレームメモリ214は、ループフィルタ部212によってフィルタされた再構成ブロックを格納する。
図43は、復号装置200の予測処理部で行われる処理の一例を示すフローチャートである。なお、予測処理部は、イントラ予測部216、インター予測部218、および予測制御部220の全てまたは一部の構成要素からなる。
イントラ予測部216は、符号化ビットストリームから読み解かれたイントラ予測モードに基づいて、ブロックメモリ210に格納されたカレントピクチャ内のブロックを参照してイントラ予測を行うことで、予測信号(イントラ予測信号)を生成する。具体的には、イントラ予測部216は、カレントブロックに隣接するブロックのサンプル(例えば輝度値、色差値)を参照してイントラ予測を行うことでイントラ予測信号を生成し、イントラ予測信号を予測制御部220に出力する。
インター予測部218は、フレームメモリ214に格納された参照ピクチャを参照して、カレントブロックを予測する。予測は、カレントブロック又はカレントブロック内のサブブロック(例えば4x4ブロック)の単位で行われる。例えば、インター予測部218は、符号化ビットストリーム(例えば、エントロピー復号部202から出力される予測パラメータ)から読み解かれた動き情報(例えば動きベクトル)を用いて動き補償を行うことでカレントブロック又はサブブロックのインター予測信号を生成し、インター予測信号を予測制御部220に出力する。
符号化ビットストリームから読み解かれた情報がノーマルインターモードを適用することを示す場合、インター予測部218は、符号化ストリームから読み解かれた情報に基づいて、MVを導出し、そのMVを用いて動き補償(予測)を行う。
予測制御部220は、イントラ予測信号及びインター予測信号のいずれかを選択し、選択した信号を予測信号として加算部208に出力する。全体的に、復号装置側の予測制御部220、イントラ予測部216およびインター予測部218の構成、機能、および処理は、符号化装置側の予測制御部128、イントラ予測部124およびインター予測部126の構成、機能、および処理と対応していてもよい。
図46は、復号装置200の実装例を示すブロック図である。復号装置200は、プロセッサb1及びメモリb2を備える。例えば、図41に示された復号装置200の複数の構成要素は、図46に示されたプロセッサb1及びメモリb2によって実装される。
各用語は一例として、以下のような定義であってもよい。
符号化装置のインター予測部126(図1参照)では、時間的に前後のピクチャに加えて、処理対象ブロックを含むピクチャ(いわゆる、カレントピクチャ)における復号済みの画素(つまり、既に符号化され復号された画素)を参照することができる。また、インター予測部126は、画面内の画素のみを参照することもできる。このような予測モードを、イントラ・ブロック・コピー(IBC:Intra Block Copy)モードと呼ぶ。IBCモードは、通常のインター予測の一つのモードとして用いられてもよく、例えば、マージモード、ノーマルインターモード、および、スキップモードなどと共に用いられてもよい。以下、IBCモードについて図面を参照しながらより具体的に説明する。
以下、第1態様に係る符号化装置100、復号装置200、符号化方法及び復号方法について説明する。第1態様に係る符号化装置100及び復号装置200は、第1動きベクトルを用いて処理対象ブロック(以下、処理対象CUともいう)の予測画像を生成し、第1動きベクトルを有する第1候補を用いて、処理済みのブロック(以下、処理済みのCUともいう)で用いられた第2動きベクトルを有する複数の第2候補をFIFO(First In First Out)方式で格納するHMVP(History based Motion Vector Predictor)テーブルを更新する。
以下、HVMPモードについて図48を参照しながらより具体的に説明する。図48は、HMVPモードについて説明するための図である。図中の候補MVPリストは、マージモード用の予測候補リストであってもよく、AMVPモード用の予測候補リスト(以下、AMVP候補リストという)であってもよい。なお、図中のMVPおよびHMVPの後ろに付された数字は、リストおよびバッファに登録された順番を示している。
本開示の第1態様は、HMVPテーブルを使用するAMVP候補リストの生成に処理対象ブロックのサイズによる制約を導入する。これにより、符号化装置100および復号装置200は、処理対象ブロックのサイズが閾値サイズ以下である場合に、HMVPテーブルを使用せずにAMVP候補リストを生成することができる。言い換えると、符号化装置100および復号装置200は、AMVP候補リストの生成において、HMVPテーブルに格納されている候補MVPとAMVP候補リストに登録されている候補MVPとを比較する処理をスキップすることができる。したがって、本開示の第1態様に係る符号化装置100および復号装置200によれば、処理量が低減されるため、符号化装置100の符号化効率および復号装置200の処理効率が向上される。
以下、第2態様に係る符号化装置100、復号装置200、符号化方法及び復号方法について説明する。第1態様では、AMVP候補リストの生成処理について説明したが、第2態様では、HMVPテーブルの更新処理について説明する。
本開示の第2態様は、HMVPテーブルの更新に処理対象ブロックのサイズによる制約を導入する。当該更新処理は、処理対象ブロックのサイズが小さい場合(例えば、閾値サイズ以下である場合)に、サイクル数を減らしてもよい。
ここで開示された1以上の態様を本開示における他の態様の少なくとも一部と組み合わせて実施してもよい。また、ここで開示された1以上の態様のフローチャートに記載の一部の処理、装置の一部の構成、シンタックスの一部などを他の態様と組み合わせて実施してもよい。
上記に示された符号化装置100及び復号装置200の処理の代表例を以下に示す。
ここで開示された1以上の態様を本開示における他の態様の少なくとも一部と組み合わせて実施してもよい。また、ここで開示された1以上の態様のフローチャートに記載の一部の処理、装置の一部の構成、シンタックスの一部などを他の態様と組み合わせて実施してもよい。
以上の各実施の形態において、機能的又は作用的なブロックの各々は、通常、MPU(micro proccessing unit)及びメモリ等によって実現可能である。また、機能ブロックの各々による処理は、ROM等の記録媒体に記録されたソフトウェア(プログラム)を読み出して実行するプロセッサなどのプログラム実行部として実現されてもよい。当該ソフトウェアは、配布されてもよい。当該ソフトウェアは、半導体メモリなどの様々な記録媒体に記録されてもよい。なお、各機能ブロックをハードウェア(専用回路)によって実現することも可能である。ハードウェア及びソフトウェアの様々な組み合わせが採用され得る。
図57は、コンテンツ配信サービスを実現する適切なコンテンツ供給システムex100の全体構成を示す図である。通信サービスの提供エリアを所望の大きさに分割し、各セル内にそれぞれ、図示された例における固定無線局である基地局ex106、ex107、ex108、ex109、ex110が設置されている。
また、ストリーミングサーバex103は複数のサーバ又は複数のコンピュータであって、データを分散して処理したり記録したり配信するものであってもよい。例えば、ストリーミングサーバex103は、CDN(Contents Delivery Network)により実現され、世界中に分散された多数のエッジサーバとエッジサーバ間をつなぐネットワークによりコンテンツ配信が実現されていてもよい。CDNでは、クライアントに応じて物理的に近いエッジサーバが動的に割り当てられ得る。そして、当該エッジサーバにコンテンツがキャッシュ及び配信されることで遅延を減らすことができる。また、いくつかのタイプのエラーが発生した場合又はトラフィックの増加などにより通信状態が変わる場合に複数のエッジサーバで処理を分散したり、他のエッジサーバに配信主体を切り替えたり、障害が生じたネットワークの部分を迂回して配信を続けることができるので、高速かつ安定した配信が実現できる。
互いにほぼ同期した複数のカメラex113及び/又はスマートフォンex115などの端末により撮影された異なるシーン、又は、同一シーンを異なるアングルから撮影した画像或いは映像を統合して利用することが増えてきている。各端末で撮影した映像は、別途取得した端末間の相対的な位置関係、又は、映像に含まれる特徴点が一致する領域などに基づいて統合され得る。
コンテンツの切り替えに関して、図58に示す、上記各実施の形態で示した動画像符号化方法を応用して圧縮符号化されたスケーラブルなストリームを用いて説明する。サーバは、個別のストリームとして内容は同じで質の異なるストリームを複数有していても構わないが、図示するようにレイヤに分けて符号化を行うことで実現される時間的/空間的スケーラブルなストリームの特徴を活かして、コンテンツを切り替える構成であってもよい。つまり、復号側が性能という内的要因と通信帯域の状態などの外的要因とに応じてどのレイヤを復号するかを決定することで、復号側は、低解像度のコンテンツと高解像度のコンテンツとを自由に切り替えて復号できる。例えばユーザが移動中にスマートフォンex115で視聴していた映像の続きを、例えば帰宅後にインターネットTV等の機器で視聴したい場合には、当該機器は、同じストリームを異なるレイヤまで復号すればよいので、サーバ側の負担を軽減できる。
図60は、コンピュータex111等におけるwebページの表示画面例を示す図である。図61は、スマートフォンex115等におけるwebページの表示画面例を示す図である。図60及び図61に示すようにwebページが、画像コンテンツへのリンクであるリンク画像を複数含む場合があり、閲覧するデバイスによってその見え方は異なっていてもよい。画面上に複数のリンク画像が見える場合には、ユーザが明示的にリンク画像を選択するまで、又は画面の中央付近にリンク画像が近付く或いはリンク画像の全体が画面内に入るまで、表示装置(復号装置)は、リンク画像として各コンテンツが有する静止画又はIピクチャを表示してもよいし、複数の静止画又はIピクチャ等でgifアニメのような映像を表示してもよいし、ベースレイヤのみを受信し、映像を復号及び表示してもよい。
また、車の自動走行又は走行支援のため2次元又は3次元の地図情報などのような静止画又は映像データを送受信する場合、受信端末は、1以上のレイヤに属する画像データに加えて、メタ情報として天候又は工事の情報なども受信し、これらを対応付けて復号してもよい。なお、メタ情報は、レイヤに属してもよいし、単に画像データと多重化されてもよい。
また、コンテンツ供給システムex100では、映像配信業者による高画質で長時間のコンテンツのみならず、個人による低画質で短時間のコンテンツのユニキャスト、又はマルチキャスト配信が可能である。このような個人のコンテンツは今後も増加していくと考えられる。個人コンテンツをより優れたコンテンツにするために、サーバは、編集処理を行ってから符号化処理を行ってもよい。これは、例えば、以下のような構成を用いて実現できる。
また、これらの符号化又は復号処理は、一般的に各端末が有するLSIex500において処理される。LSI(large scale integration circuitry)ex500(図57参照)は、ワンチップであっても複数チップからなる構成であってもよい。なお、動画像符号化又は復号用のソフトウェアをコンピュータex111等で読み取り可能な何らかの記録メディア(CD-ROM、フレキシブルディスク、又はハードディスクなど)に組み込み、そのソフトウェアを用いて符号化又は復号処理を行ってもよい。さらに、スマートフォンex115がカメラ付きである場合には、そのカメラで取得した動画データを送信してもよい。このときの動画データはスマートフォンex115が有するLSIex500で符号化処理されたデータであってもよい。
図62は、図57に示されたスマートフォンex115のさらに詳細を示す図である。また、図63は、スマートフォンex115の構成例を示す図である。スマートフォンex115は、基地局ex110との間で電波を送受信するためのアンテナex450と、映像及び静止画を撮ることが可能なカメラ部ex465と、カメラ部ex465で撮像した映像、及びアンテナex450で受信した映像等が復号されたデータを表示する表示部ex458とを備える。スマートフォンex115は、さらに、タッチパネル等である操作部ex466と、音声又は音響を出力するためのスピーカ等である音声出力部ex457と、音声を入力するためのマイク等である音声入力部ex456と、撮影した映像或いは静止画、録音した音声、受信した映像或いは静止画、メール等の符号化されたデータ、又は、復号化されたデータを保存可能なメモリ部ex467と、ユーザを特定し、ネットワークをはじめ各種データへのアクセスの認証をするためのSIMex468とのインタフェース部であるスロット部ex464とを備える。なお、メモリ部ex467の代わりに外付けメモリが用いられてもよい。
102 分割部
104 減算部
106 変換部
108 量子化部
110 エントロピー符号化部
112、204 逆量子化部
114、206 逆変換部
116、208 加算部
118、210 ブロックメモリ
120、212 ループフィルタ部
122、214 フレームメモリ
124、216 イントラ予測部
126、218 インター予測部
128、220 予測制御部
200 復号装置
202 エントロピー復号部
1201 境界判定部
1202、1204、1206 スイッチ
1203 フィルタ判定部
1205 フィルタ処理部
1207 フィルタ特性決定部
1208 処理判定部
a1、b1 プロセッサ
a2、b2 メモリ
Claims (22)
- 回路と、
前記回路に接続されたメモリと、を備え、
前記回路は、動作において、
第1動きベクトルを用いて処理対象ブロックの予測画像を生成し、
前記第1動きベクトルを有する第1候補を用いて、処理済みのブロックで用いられた第2動きベクトルを有する複数の第2候補をFIFO(First In First Out)方式で格納するHMVP(History based Motion Vector Predictor)テーブルを更新し、
前記HMVPテーブルの更新において、
前記処理対象ブロックのサイズが閾値サイズ以下であるか否かを判定し、
前記処理対象ブロックのサイズが前記閾値サイズ以下であると判定された場合、前記HMVPテーブルの更新をスキップする、
符号化装置。 - 前記回路は、さらに、
複数の予測動きベクトル候補を含む候補MVP(Motion Vector Prediction)リストを生成し、
生成された前記候補MVPリストに含まれる複数の予測動きベクトル候補のうちの1つを用いて前記第1動きベクトルを符号化し、
前記候補MVPリストの生成において、
前記処理対象ブロックのサイズが前記閾値サイズ以下である場合、前記HMVPテーブルの使用を禁止し、
前記処理対象ブロックのサイズが前記閾値サイズより大きい場合、前記HMVPテーブルの使用を許可する、
請求項1に記載の符号化装置。 - 前記処理対象ブロックのサイズは、前記処理対象ブロック内の画素数で定義される、
請求項1又は2に記載の符号化装置。 - 前記閾値サイズは、16画素である、
請求項3に記載の符号化装置。 - 前記処理対象ブロックのサイズは、前記処理対象ブロックの幅又は高さで定義される、
請求項1又は2に記載の符号化装置。 - 前記回路は、前記処理対象ブロックの予測画像の生成において、前記処理対象ブロックが属するピクチャとは異なる符号化済みのピクチャを参照するインターモードを用いる、
請求項1~5のいずれか1項に記載の符号化装置。 - 前記回路は、前記処理対象ブロックの予測画像の生成において、前記処理対象ブロックが属するピクチャの符号化済みの領域を参照するIBC(Intra Block Copy)モードを用いる、
請求項1~5のいずれか1項に記載の符号化装置。 - 前記第1候補は、前記第1動きベクトルに対応する第1参照ピクチャ情報を有し、
前記複数の第2候補の各々は、前記第2動きベクトルに対応する第2参照ピクチャ情報を有し、
前記回路は、前記HMVPテーブルの更新において、
前記第1候補が、前記複数の第2候補のいずれかと一致するか否かを判定し、
前記第1候補が前記複数の第2候補のいずれとも一致しない場合、前記第1候補を前記HMVPテーブルに格納することにより、前記HMVPテーブルを更新する、
請求項1~7のいずれか1項に記載の符号化装置。 - 前記候補MVPリストは、AMVP(Adaptive Motion Vector Prediction)モードにおける候補MVPリストである、
請求項1~8のいずれか1項に記載の符号化装置。 - 前記候補MVPリストは、マージモードにおける候補MVPリストである、
請求項1~8のいずれか1項に記載の符号化装置。 - 回路と、
前記回路に接続されたメモリと、を備え、
前記回路は、動作において、
第1動きベクトルを用いて処理対象ブロックの予測画像を生成し、
前記第1動きベクトルを有する第1候補を用いて、処理済みのブロックで用いられた第2動きベクトルを有する複数の第2候補をFIFO方式で格納するHMVPテーブルを更新し、
前記HMVPテーブルの更新において、
前記処理対象ブロックのサイズが閾値サイズ以下であるか否かを判定し、
前記処理対象ブロックのサイズが前記閾値サイズ以下であると判定された場合、前記HMVPテーブルの更新をスキップする、
復号装置。 - 前記回路は、さらに、
複数の予測動きベクトル候補を含む候補MVPリストを生成し、
生成された前記候補MVPリストに含まれる複数の予測動きベクトル候補のうちの1つを用いて前記第1動きベクトルを復号し、
前記候補MVPリストの生成において、
前記処理対象ブロックのサイズが前記閾値サイズ以下である場合、前記HMVPテーブルの使用を禁止し、
前記処理対象ブロックのサイズが前記閾値サイズより大きい場合、前記HMVPテーブルの使用を許可する、
請求項11に記載の復号装置。 - 前記処理対象ブロックのサイズは、前記処理対象ブロック内の画素数で定義される、
請求項11又は12に記載の復号装置。 - 前記閾値サイズは、16画素である、
請求項13に記載の復号装置。 - 前記処理対象ブロックのサイズは、前記処理対象ブロックの幅又は高さで定義される、
請求項11又は12に記載の復号装置。 - 前記回路は、前記処理対象ブロックの予測画像の生成において、前記処理対象ブロックが属するピクチャとは異なる符号化済みのピクチャを参照するインターモードを用いる、
請求項11~15のいずれか1項に記載の復号装置。 - 前記回路は、前記処理対象ブロックの予測画像の生成において、前記処理対象ブロックが属するピクチャの符号化済みの領域を参照するIBCモードを用いる、
請求項11~15のいずれか1項に記載の復号装置。 - 前記第1候補は、前記第1動きベクトルに対応する第1参照ピクチャ情報を有し、
前記複数の第2候補の各々は、前記第2動きベクトルに対応する第2参照ピクチャ情報を有し、
前記回路は、前記HMVPテーブルの更新において、
前記第1候補が、前記複数の第2候補のいずれかと一致するか否かを判定し、
前記第1候補が前記複数の第2候補のいずれとも一致しない場合、前記第1候補を前記HMVPテーブルに格納することにより、前記HMVPテーブルを更新する、
請求項11~17のいずれか1項に記載の復号装置。 - 前記候補MVPリストは、AMVPモードにおける候補MVPリストである、
請求項11~18のいずれか1項に記載の復号装置。 - 前記候補MVPリストは、マージモードにおける候補MVPリストである、
請求項11~18のいずれか1項に記載の復号装置。 - 第1動きベクトルを用いて処理対象ブロックの予測画像を生成し、
前記第1動きベクトルを有する第1候補を用いて、処理済みのブロックで用いられた第2動きベクトルを有する複数の第2候補をFIFO方式で格納するHMVPテーブルを更新し、
前記HMVPテーブルの更新において、
前記処理対象ブロックのサイズが閾値サイズ以下であるか否かを判定し、
前記処理対象ブロックのサイズが前記閾値サイズ以下であると判定された場合、前記HMVPテーブルの更新をスキップする、
符号化方法。 - 第1動きベクトルを用いて処理対象ブロックの予測画像を生成し、
前記第1動きベクトルを有する第1候補を用いて、処理済みのブロックで用いられた第2動きベクトルを有する複数の第2候補をFIFO方式で格納するHMVPテーブルを更新し、
前記HMVPテーブルの更新において、
前記処理対象ブロックのサイズが閾値サイズ以下であるか否かを判定し、
前記処理対象ブロックのサイズが前記閾値サイズ以下であると判定された場合、前記HMVPテーブルの更新をスキップする、
復号方法。
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BR112021014711A2 (pt) | 2021-09-28 |
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