WO2020143585A1 - 视频编码器、视频解码器及相应方法 - Google Patents

视频编码器、视频解码器及相应方法 Download PDF

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Publication number
WO2020143585A1
WO2020143585A1 PCT/CN2020/070520 CN2020070520W WO2020143585A1 WO 2020143585 A1 WO2020143585 A1 WO 2020143585A1 CN 2020070520 W CN2020070520 W CN 2020070520W WO 2020143585 A1 WO2020143585 A1 WO 2020143585A1
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image
knowledge
decoded
images
current
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English (en)
French (fr)
Inventor
虞露
王业奎
范宇群
于化龙
赵寅
林翔宇
杨海涛
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to KR1020217024167A priority Critical patent/KR102609215B1/ko
Priority to EP20738233.4A priority patent/EP3896974A4/en
Publication of WO2020143585A1 publication Critical patent/WO2020143585A1/zh
Priority to US17/366,735 priority patent/US11496754B2/en
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    • 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
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    • H—ELECTRICITY
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    • 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
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    • 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
    • H04N19/172—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 picture, frame or field
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Definitions

  • the present invention relates to the field of video encoding and decoding, and in particular to a video image encoding and decoding method, device, and corresponding encoder and decoder.
  • Digital video capabilities can be incorporated into a variety of devices, including digital TVs, digital live broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, Digital cameras, digital recording devices, digital media players, video game devices, video game consoles, cellular or satellite radio phones (so-called "smart phones"), video teleconferencing devices, video streaming devices, and the like .
  • Digital video devices implement video compression technology, for example, in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4 Part 10 Advanced Video Coding (AVC), The video compression technology described in the video coding standard H.265/High Efficiency Video Coding (HEVC) standard and extensions to such standards.
  • Video devices can more efficiently transmit, receive, encode, decode, and/or store digital video information by implementing such video compression techniques.
  • Video compression techniques perform spatial (intra-image) prediction and/or temporal (inter-image) prediction to reduce or remove the redundancy inherent in the video sequence.
  • a video slice ie, a video frame or a portion of a video frame
  • the image blocks in the to-be-intra-coded (I) slice of the image are encoded using spatial prediction with reference samples in adjacent blocks in the same image.
  • An image block in an inter-coded (P or B) slice of an image may use spatial prediction relative to reference samples in neighboring blocks in the same image or temporal prediction relative to reference samples in other reference images.
  • the image may be referred to as a frame, and the reference image may be referred to as a reference frame.
  • Embodiments of the present application provide a video image encoding and decoding method, device, and corresponding encoder and decoder, which improves the prediction accuracy of motion information of an image block to a certain extent, thereby improving encoding and decoding performance.
  • an embodiment of the present application provides a video decoding method, including:
  • a preset number of knowledge images are determined as candidate reference images of the current decoded image.
  • an embodiment of the present application provides a decoding device, including a plurality of functional units for implementing any method of the first aspect.
  • the decoding device may include:
  • a first obtaining module configured to obtain a first identifier from the code stream, where the first identifier is used to indicate a minimum decoding time interval k between knowledge images allowed by the code stream;
  • the second acquisition module is used to decode if the current decoded image refers to the knowledge image
  • the determining module is configured to determine a preset number of knowledge images as candidate reference images of the current decoded image according to the relationship between the difference between t i and t j and the magnitude of k.
  • the k is not less than a minimum decoding time allowed by a profile or level that the code stream conforms to.
  • n knowledge images are determined as candidate reference images of the current decoded image include:
  • n knowledge images are determined as candidate reference images of the current decoded image; the n knowledge images include knowledge images that are not currently decoded or need to be decoded again, n is positive Integer.
  • n knowledge images are determined as candidate reference images of the current decoded image; where, m
  • the knowledge images include decoded knowledge images, and the n knowledge images include knowledge images that are not currently decoded or need to be re-decoded.
  • m and n are positive integers.
  • the determining n knowledge images as candidate reference images of the current decoded image includes:
  • n knowledge images with the highest similarity to the content of the current decoded image are determined.
  • the determining n knowledge images as candidate reference images of the current decoded image includes:
  • n knowledge images that are closest to the display time of the current decoded image are determined.
  • the determining n knowledge images as candidate reference images of the current decoded image includes:
  • n knowledge images are determined as candidate reference images of the current decoded image include:
  • m knowledge images are determined as candidate reference images of the current decoded image; where the m knowledge images include decoded knowledge images that do not need to be re-encoded, and m is a positive integer.
  • an embodiment of the present application provides a video decoding method, including:
  • the first decoded image is the most recent image in the main codestream immediately before the current image to be decoded, which supports random access and only refers to the knowledge image;
  • the current image to be decoded is an image that supports random access and only references the knowledge image
  • the number of decoded images between the current image to be decoded and the first decoded image is at least f*k; the k is one of the knowledge images allowed by the main code stream Minimum decoding time interval; f is the frame rate of the video sequence declared in the main stream; the number of the new knowledge images is not greater than a preset value n; the n is a positive integer; the new The knowledge image is a knowledge image that is not referenced by the first decoded image among the knowledge images referenced by the current image to be decoded.
  • an embodiment of the present application provides a video decoding device.
  • the device includes:
  • a second acquisition module configured to acquire a first decoded image; the first decoded image in the main codestream immediately before the current image to be decoded immediately following the sequence header and supports random access and only references knowledge images;
  • a determining module configured to use the new knowledge image as a reference image of the current image to be decoded; the current image to be decoded is an image that supports random access and only references the knowledge image;
  • the number of decoded images between the current image to be decoded and the first decoded image is at least f*k; the k is one of the knowledge images allowed by the main code stream Minimum decoding time interval; f is the frame rate of the video sequence declared in the main stream; the number of the new knowledge images is not greater than a preset value n; the n is a positive integer; the new The knowledge image is a knowledge image that is not referenced by the first decoded image among the knowledge images referenced by the current image to be decoded.
  • the method further includes: decoding the current image to be decoded according to the new knowledge image.
  • the above-mentioned device further includes a decoding module for performing this step.
  • n 1
  • the new knowledge image is obtained by decoding a knowledge base code stream.
  • an embodiment of the present application provides an apparatus for decoding video data.
  • the apparatus includes:
  • Memory used to store video data in the form of code stream
  • the video decoder is used to perform any possible implementation method in the first aspect or the third aspect.
  • an embodiment of the present application provides an apparatus for encoding video data.
  • the apparatus includes:
  • a memory for storing video data, the video data including one or more image blocks
  • the video encoder is used to implement any possible implementation method coupled with the first aspect or the third aspect.
  • an embodiment of the present application provides an encoding device, including: a non-volatile memory and a processor coupled to each other, and the processor calls program codes stored in the memory to execute any of the first aspect A method that couples some or all of the steps.
  • an embodiment of the present application provides a decoding device, including: a non-volatile memory and a processor coupled to each other, and the processor calls program codes stored in the memory to perform any one of the first aspect Some or all steps of this method.
  • an embodiment of the present application provides a computer-readable storage medium that stores a program code, where the program code includes a part or part for performing any one of the methods of the first aspect or Instructions for all steps.
  • an embodiment of the present application provides a computer program product that, when the computer program product runs on a computer, causes the computer to perform part or all of the steps of any one of the methods of the first aspect.
  • FIG. 1A is a block diagram of an example of a video encoding and decoding system 10 for implementing an embodiment of the present invention
  • FIG. 1B is a block diagram of an example of a video decoding system 40 for implementing an embodiment of the present invention
  • FIG. 2 is a block diagram of an example structure of an encoder 20 for implementing an embodiment of the present invention
  • FIG. 3 is a block diagram of an example structure of a decoder 30 for implementing an embodiment of the present invention.
  • FIG. 4 is a block diagram of an example of a video decoding device 400 for implementing an embodiment of the present invention
  • FIG. 5 is a block diagram of another example of an encoding device or a decoding device used to implement an embodiment of the present invention.
  • 6A is an example of a possible structure code stream in an embodiment of the present invention.
  • 6B is an example of a possible structure code stream in an embodiment of the present invention.
  • 6C is an example of a possible structure code stream in an embodiment of the present invention.
  • 7A is an example of a possible structure code stream in an embodiment of the present invention.
  • 7C is an example of a possible structure code stream in an embodiment of the present invention.
  • 8A is an example of a possible structure code stream in an embodiment of the present invention.
  • 8B is an example of a possible structure code stream in an embodiment of the present invention.
  • 8C is an example of a possible structure code stream in an embodiment of the present invention.
  • 9A is an example of a possible structure code stream in an embodiment of the present invention.
  • 9B is an example of a possible structure code stream in an embodiment of the present invention.
  • 9C is an example of a possible structure code stream in an embodiment of the present invention.
  • 9D is a schematic flowchart of a decoding method in an embodiment of the present invention.
  • 10A is an example of a possible structure code stream in an embodiment of the present invention.
  • 10B is an example of a possible structure code stream in an embodiment of the present invention.
  • 10C is an example of a possible structure code stream in an embodiment of the present invention.
  • FIG. 11 is a schematic flowchart of a decoding method for implementing an embodiment of the present invention.
  • FIG. 12 is a structural block diagram of a device for implementing an embodiment of the present invention.
  • the corresponding device may include one or more units such as functional units to perform the one or more method steps described (eg, one unit performs one or more steps , Or multiple units, each of which performs one or more of multiple steps), even if such one or more units are not explicitly described or illustrated in the drawings.
  • the corresponding method may include a step to perform the functionality of one or more units (eg, one step executes one or more units Functionality, or multiple steps, each of which performs the functionality of one or more of the multiple units), even if such one or more steps are not explicitly described or illustrated in the drawings.
  • the features of the exemplary embodiments and/or aspects described herein may be combined with each other.
  • Video coding generally refers to processing a sequence of pictures that form a video or video sequence.
  • picture In the field of video coding, the terms “picture”, “frame” or “image” may be used as synonyms.
  • Video coding as used herein means video coding or video decoding.
  • Video encoding is performed on the source side and usually includes processing (eg, by compressing) the original video picture to reduce the amount of data required to represent the video picture, thereby storing and/or transmitting more efficiently.
  • Video decoding is performed on the destination side and usually involves inverse processing relative to the encoder to reconstruct the video picture.
  • the “encoding” of video pictures involved in the embodiments should be understood as referring to the “encoding” or “decoding” of video sequences.
  • the combination of the encoding part and the decoding part is also called codec (encoding and decoding).
  • the video sequence includes a series of pictures, the picture is further divided into slices, and the slices are further divided into blocks.
  • Video coding is performed in units of blocks.
  • the concept of blocks is further expanded.
  • MB macroblock
  • the macroblock can be further divided into multiple prediction blocks (partitions) that can be used for predictive coding.
  • HEVC high-efficiency video coding
  • the basic concepts such as coding unit (CU), prediction unit (PU) and transform unit (TU) are adopted.
  • CU coding unit
  • PU prediction unit
  • TU transform unit
  • a variety of block units are divided and described in a new tree-based structure.
  • the CU can be divided into smaller CUs according to the quadtree, and the smaller CUs can be further divided to form a quadtree structure.
  • the CU is the basic unit for dividing and coding the encoded image.
  • PU can correspond to the prediction block and is the basic unit of predictive coding.
  • the CU is further divided into multiple PUs according to the division mode.
  • the TU can correspond to the transform block and is the basic unit for transforming the prediction residual.
  • PU or TU they all belong to the concept of block (or image block) in essence.
  • the CTU is split into multiple CUs by using a quadtree structure represented as a coding tree.
  • a decision is made at the CU level whether to use inter-picture (temporal) or intra-picture (spatial) prediction to encode picture regions.
  • Each CU can be further split into one, two, or four PUs according to the PU split type.
  • the same prediction process is applied within a PU, and related information is transmitted to the decoder on the basis of the PU.
  • the CU may be divided into transform units (TU) according to other quadtree structures similar to the coding tree used for the CU.
  • quad-tree and binary-tree Quad-tree and binary-tree (Quad-tree and binary tree, QTBT) split frames are used to split code blocks.
  • the CU may have a square or rectangular shape.
  • the image block to be encoded in the current encoded image may be referred to as the current block.
  • the reference block is a block that provides a reference signal for the current block, where the reference signal represents a pixel value within the image block.
  • the block in the reference image that provides the prediction signal for the current block may be a prediction block, where the prediction signal represents a pixel value or a sample value or a sample signal within the prediction block. For example, after traversing multiple reference blocks, the best reference block is found. This best reference block will provide a prediction for the current block. This block is called a prediction block.
  • the original video picture can be reconstructed, that is, the reconstructed video picture has the same quality as the original video picture (assuming no transmission loss or other data loss during storage or transmission).
  • further compression is performed by, for example, quantization to reduce the amount of data required to represent the video picture, but the decoder side cannot fully reconstruct the video picture, that is, the quality of the reconstructed video picture is better than the original video picture. The quality is lower or worse.
  • Several video coding standards of H.261 belong to "lossy hybrid video codec” (ie, combining spatial and temporal prediction in the sample domain with 2D transform coding for applying quantization in the transform domain).
  • Each picture of a video sequence is usually divided into non-overlapping block sets, which are usually encoded at the block level.
  • the encoder side usually processes the encoded video at the block (video block) level.
  • the prediction block is generated by spatial (intra-picture) prediction and temporal (inter-picture) prediction.
  • the encoder duplicates the decoder processing loop so that the encoder and decoder generate the same prediction (eg, intra-frame prediction and inter-frame prediction) and/or reconstruction for processing, ie encoding subsequent blocks.
  • FIG. 1A exemplarily shows a schematic block diagram of a video encoding and decoding system 10 applied in an embodiment of the present invention.
  • the video encoding and decoding system 10 may include a source device 12 and a destination device 14, the source device 12 generates encoded video data, and therefore, the source device 12 may be referred to as a video encoding device.
  • the destination device 14 may decode the encoded video data generated by the source device 12, and therefore, the destination device 14 may be referred to as a video decoding device.
  • Source device 12, destination device 14, or both may include one or more processors and a memory coupled to the one or more processors.
  • the memory may include, but is not limited to, RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store the desired program code in the form of instructions or data structures accessible by the computer, as described herein.
  • Source device 12 and destination device 14 may include various devices, including desktop computers, mobile computing devices, notebook (eg, laptop) computers, tablet computers, set-top boxes, telephone handsets such as so-called "smart" phones, etc. Devices, televisions, cameras, display devices, digital media players, video game consoles, in-vehicle computers, wireless communication devices, or the like.
  • FIG. 1A depicts the source device 12 and the destination device 14 as separate devices
  • device embodiments may also include both the source device 12 and the destination device 14 or the functionality of both, ie the source device 12 or the corresponding And the destination device 14 or the corresponding functionality.
  • the same hardware and/or software may be used, or separate hardware and/or software, or any combination thereof may be used to implement the source device 12 or corresponding functionality and the destination device 14 or corresponding functionality .
  • a communication connection can be made between the source device 12 and the destination device 14 via the link 13, and the destination device 14 can receive the encoded video data from the source device 12 via the link 13.
  • Link 13 may include one or more media or devices capable of moving the encoded video data from source device 12 to destination device 14.
  • link 13 may include one or more communication media that enable source device 12 to transmit encoded video data directly to destination device 14 in real time.
  • the source device 12 may modulate the encoded video data according to a communication standard (eg, a wireless communication protocol), and may transmit the modulated video data to the destination device 14.
  • the one or more communication media may include wireless and/or wired communication media, such as a radio frequency (RF) spectrum or one or more physical transmission lines.
  • RF radio frequency
  • the one or more communication media may form part of a packet-based network, such as a local area network, a wide area network, or a global network (eg, the Internet).
  • the one or more communication media may include routers, switches, base stations, or other devices that facilitate communication from source device 12 to destination device 14.
  • the source device 12 includes an encoder 20.
  • the source device 12 may further include a picture source 16, a picture pre-processor 18, and a communication interface 22.
  • the encoder 20, the picture source 16, the picture pre-processor 18, and the communication interface 22 may be hardware components in the source device 12, or may be software programs in the source device 12. They are described as follows:
  • Picture source 16 which can include or can be any kind of picture capture device, for example to capture real-world pictures, and/or any kind of pictures or comments (for screen content encoding, some text on the screen is also considered to be encoded Part of the picture or image) generation device, for example, a computer graphics processor for generating computer animation pictures, or for acquiring and/or providing real-world pictures, computer animation pictures (for example, screen content, virtual reality, VR) pictures) in any category of equipment, and/or any combination thereof (eg, augmented reality (AR) pictures).
  • the picture source 16 may be a camera for capturing pictures or a memory for storing pictures.
  • the picture source 16 may also include any type of (internal or external) interface that stores previously captured or generated pictures and/or acquires or receives pictures.
  • the picture source 16 When the picture source 16 is a camera, the picture source 16 may be, for example, a local or integrated camera integrated in the source device; when the picture source 16 is a memory, the picture source 16 may be a local or integrated, for example, integrated in the source device Memory.
  • the interface When the picture source 16 includes an interface, the interface may be, for example, an external interface that receives pictures from an external video source.
  • the external video source is, for example, an external picture capture device, such as a camera, an external memory, or an external picture generation device.
  • the external picture generation device for example It is an external computer graphics processor, computer or server.
  • the interface may be any type of interface according to any proprietary or standardized interface protocol, such as a wired or wireless interface, an optical interface.
  • the picture can be regarded as a two-dimensional array or matrix of pixels.
  • the pixels in the array can also be called sampling points.
  • the number of sampling points in the horizontal and vertical directions (or axes) of the array or picture defines the size and/or resolution of the picture.
  • three color components are usually used, that is, a picture can be represented or contain three sampling arrays.
  • the picture includes corresponding red, green, and blue sampling arrays.
  • each pixel is usually expressed in a luminance/chrominance format or color space.
  • YUV format picture it includes the luminance component indicated by Y (sometimes also indicated by L) and the two indicated by U and V.
  • the luma component Y represents luminance or gray-scale horizontal intensity (for example, both are the same in gray-scale pictures), and the two chroma components U and V represent chroma or color information components.
  • the picture in the YUV format includes a luminance sampling array of luminance sampling values (Y), and two chrominance sampling arrays of chrominance values (U and V). RGB format pictures can be converted or transformed into YUV format and vice versa, this process is also called color transformation or conversion. If the picture is black and white, the picture may include only the brightness sampling array.
  • the picture transmitted from the picture source 16 to the picture processor may also be referred to as original picture data 17.
  • the picture pre-processor 18 is configured to receive the original picture data 17 and perform pre-processing on the original picture data 17 to obtain the pre-processed picture 19 or the pre-processed picture data 19.
  • the pre-processing performed by the picture pre-processor 18 may include trimming, color format conversion (eg, conversion from RGB format to YUV format), color toning, or denoising.
  • the encoder 20 (or video encoder 20) is used to receive the pre-processed picture data 19, and process the pre-processed picture data 19 using a related prediction mode (such as the prediction mode in various embodiments herein), thereby
  • the encoded picture data 21 is provided (the structural details of the encoder 20 will be further described below based on FIG. 2 or FIG. 4 or FIG. 5).
  • the encoder 20 may be used to implement various embodiments described below to implement the application of the chroma block prediction method described in the present invention on the encoding side.
  • the communication interface 22 can be used to receive the encoded picture data 21, and can transmit the encoded picture data 21 to the destination device 14 or any other device (such as a memory) through the link 13 for storage or direct reconstruction.
  • the other device may be any device used for decoding or storage.
  • the communication interface 22 may be used, for example, to encapsulate the encoded picture data 21 into a suitable format, such as a data packet, for transmission on the link 13.
  • the destination device 14 includes a decoder 30, and optionally, the destination device 14 may further include a communication interface 28, a picture post-processor 32, and a display device 34. They are described as follows:
  • the communication interface 28 may be used to receive the encoded picture data 21 from the source device 12 or any other source, such as a storage device, such as an encoded picture data storage device.
  • the communication interface 28 can be used to transmit or receive the encoded picture data 21 via the link 13 between the source device 12 and the destination device 14 or through any type of network.
  • the link 13 is, for example, a direct wired or wireless connection.
  • the category of network is, for example, a wired or wireless network or any combination thereof, or any category of private network and public network, or any combination thereof.
  • the communication interface 28 may be used, for example, to decapsulate the data packet transmitted by the communication interface 22 to obtain the encoded picture data 21.
  • Both the communication interface 28 and the communication interface 22 can be configured as a one-way communication interface or a two-way communication interface, and can be used, for example, to send and receive messages to establish a connection, confirm and exchange any other communication link and/or for example encoded picture data Information about data transmission.
  • the decoder 30 (or referred to as the decoder 30) is used to receive the encoded picture data 21 and provide the decoded picture data 31 or the decoded picture 31 (hereinafter, the decoder 30 will be further described based on FIG. 3 or FIG. 4 or FIG. 5 Structural details).
  • the decoder 30 may be used to implement various embodiments described below to implement the application of the chroma block prediction method described in the present invention on the decoding side.
  • the post-picture processor 32 is configured to perform post-processing on the decoded picture data 31 (also referred to as reconstructed picture data) to obtain post-processed picture data 33.
  • the post-processing performed by the image post-processor 32 may include: color format conversion (for example, conversion from YUV format to RGB format), color adjustment, retouching or resampling, or any other processing, and may also be used to convert the post-processed image data 33transmitted to the display device 34.
  • the display device 34 is used to receive post-processed picture data 33 to display pictures to a user or viewer, for example.
  • the display device 34 may be or may include any type of display for presenting reconstructed pictures, for example, an integrated or external display or monitor.
  • the display may include a liquid crystal display (liquid crystal display (LCD), organic light emitting diode (OLED) display, plasma display, projector, micro LED display, liquid crystal on silicon (LCoS), Digital light processor (digital light processor, DLP) or any other type of display.
  • FIG. 1A illustrates the source device 12 and the destination device 14 as separate devices
  • device embodiments may also include the functionality of the source device 12 and the destination device 14 or both, ie, the source device 12 or The corresponding functionality and the destination device 14 or corresponding functionality.
  • the same hardware and/or software may be used, or separate hardware and/or software, or any combination thereof may be used to implement the source device 12 or corresponding functionality and the destination device 14 or corresponding functionality .
  • Source device 12 and destination device 14 may include any of a variety of devices, including any type of handheld or stationary devices, such as notebook or laptop computers, mobile phones, smartphones, tablets or tablet computers, cameras, desktops Computers, set-top boxes, televisions, cameras, in-vehicle devices, display devices, digital media players, video game consoles, video streaming devices (such as content service servers or content distribution servers), broadcast receiver devices, broadcast transmitter devices And so on, and can not use or use any kind of operating system.
  • handheld or stationary devices such as notebook or laptop computers, mobile phones, smartphones, tablets or tablet computers, cameras, desktops Computers, set-top boxes, televisions, cameras, in-vehicle devices, display devices, digital media players, video game consoles, video streaming devices (such as content service servers or content distribution servers), broadcast receiver devices, broadcast transmitter devices And so on, and can not use or use any kind of operating system.
  • Both the encoder 20 and the decoder 30 may be implemented as any of various suitable circuits, for example, one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (application-specific integrated circuits) circuit, ASIC), field-programmable gate array (FPGA), discrete logic, hardware, or any combination thereof.
  • DSPs digital signal processors
  • ASIC application-specific integrated circuits
  • FPGA field-programmable gate array
  • the device may store the instructions of the software in a suitable non-transitory computer-readable storage medium, and may use one or more processors to execute the instructions in hardware to perform the techniques of the present disclosure . Any one of the foregoing (including hardware, software, a combination of hardware and software, etc.) may be regarded as one or more processors.
  • the video encoding and decoding system 10 shown in FIG. 1A is only an example, and the technology of the present application may be applied to video encoding settings that do not necessarily include any data communication between encoding and decoding devices (for example, video encoding or video decoding).
  • data may be retrieved from local storage, streamed on the network, and so on.
  • the video encoding device may encode the data and store the data to the memory, and/or the video decoding device may retrieve the data from the memory and decode the data.
  • encoding and decoding are performed by devices that do not communicate with each other but only encode data to and/or retrieve data from memory and decode the data.
  • FIG. 1B is an explanatory diagram of an example of a video coding system 40 including the encoder 20 of FIG. 2 and/or the decoder 30 of FIG. 3 according to an exemplary embodiment.
  • the video decoding system 40 can implement a combination of various technologies of the embodiments of the present invention.
  • the video decoding system 40 may include an imaging device 41, an encoder 20, a decoder 30 (and/or a video encoder/decoder implemented by the logic circuit 47 of the processing unit 46), an antenna 42 , One or more processors 43, one or more memories 44, and/or display devices 45.
  • the imaging device 41, the antenna 42, the processing unit 46, the logic circuit 47, the encoder 20, the decoder 30, the processor 43, the memory 44, and/or the display device 45 can communicate with each other.
  • the video coding system 40 is shown with the encoder 20 and the decoder 30, in different examples, the video coding system 40 may include only the encoder 20 or only the decoder 30.
  • antenna 42 may be used to transmit or receive an encoded bitstream of video data.
  • the display device 45 may be used to present video data.
  • the logic circuit 47 may be implemented by the processing unit 46.
  • the processing unit 46 may include application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, and the like.
  • the video decoding system 40 may also include an optional processor 43, which may similarly include application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, and the like.
  • the logic circuit 47 may be implemented by hardware, such as dedicated hardware for video encoding, and the processor 43 may be implemented by general-purpose software, an operating system, and so on.
  • the memory 44 may be any type of memory, such as volatile memory (for example, static random access memory (Static Random Access Memory, SRAM), dynamic random access memory (Dynamic Random Access Memory, DRAM), etc.) or non-volatile Memory (for example, flash memory, etc.), etc.
  • volatile memory for example, static random access memory (Static Random Access Memory, SRAM), dynamic random access memory (Dynamic Random Access Memory, DRAM), etc.
  • non-volatile Memory for example, flash memory, etc.
  • the memory 44 may be implemented by cache memory.
  • the logic circuit 47 can access the memory 44 (eg, to implement an image buffer).
  • the logic circuit 47 and/or the processing unit 46 may include memory (eg, cache, etc.) for implementing image buffers and the like.
  • the encoder 20 implemented by logic circuits may include an image buffer (eg, implemented by the processing unit 46 or the memory 44) and a graphics processing unit (eg, implemented by the processing unit 46).
  • the graphics processing unit may be communicatively coupled to the image buffer.
  • the graphics processing unit may include the encoder 20 implemented by a logic circuit 47 to implement the various modules discussed with reference to FIG. 2 and/or any other encoder system or subsystem described herein.
  • Logic circuits can be used to perform the various operations discussed herein.
  • decoder 30 may be implemented by logic circuit 47 in a similar manner to implement the various modules discussed with reference to decoder 30 of FIG. 3 and/or any other decoder systems or subsystems described herein.
  • the decoder 30 implemented by the logic circuit may include an image buffer (implemented by the processing unit 2820 or the memory 44) and a graphics processing unit (for example, implemented by the processing unit 46).
  • the graphics processing unit may be communicatively coupled to the image buffer.
  • the graphics processing unit may include a decoder 30 implemented by a logic circuit 47 to implement various modules discussed with reference to FIG. 3 and/or any other decoder system or subsystem described herein.
  • antenna 42 may be used to receive an encoded bitstream of video data.
  • the encoded bitstream may include data related to encoded video frames, indicators, index values, mode selection data, etc. discussed herein, such as data related to encoded partitions (eg, transform coefficients or quantized transform coefficients , (As discussed) optional indicators, and/or data defining the code segmentation).
  • the video coding system 40 may also include a decoder 30 coupled to the antenna 42 and used to decode the encoded bitstream.
  • the display device 45 is used to present video frames.
  • the decoder 30 may be used to perform the reverse process.
  • the decoder 30 may be used to receive and parse such syntax elements and decode the relevant video data accordingly.
  • encoder 20 may entropy encode syntax elements into an encoded video bitstream. In such instances, decoder 30 may parse such syntax elements and decode the relevant video data accordingly.
  • the encoding and decoding methods described in the embodiments of the present invention are mainly used in the inter prediction process. This process exists in both the encoder 20 and the decoder 30.
  • the encoder 20 and the decoder 30 in the embodiments of the present invention may be For example, H.263, H.264, HEVV, MPEG-2, MPEG-4, VP8, VP9 and other video standard protocols or next-generation video standard protocols (such as H.266, etc.) corresponding codec/decoder.
  • FIG. 2 shows a schematic/conceptual block diagram of an example of an encoder 20 for implementing an embodiment of the present invention.
  • the encoder 20 includes a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a buffer 216, a loop filter Unit 220, decoded picture buffer (DPB) 230, prediction processing unit 260, and entropy encoding unit 270.
  • the prediction processing unit 260 may include an inter prediction unit 244, an intra prediction unit 254, and a mode selection unit 262.
  • the inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown).
  • the encoder 20 shown in FIG. 2 may also be referred to as a hybrid video encoder or a video encoder based on a hybrid video codec.
  • the residual calculation unit 204, the transform processing unit 206, the quantization unit 208, the prediction processing unit 260, and the entropy encoding unit 270 form the forward signal path of the encoder 20, while, for example, the inverse quantization unit 210, the inverse transform processing unit 212, the heavy
  • the structural unit 214, the buffer 216, the loop filter 220, the decoded picture buffer (DPB) 230, and the prediction processing unit 260 form a backward signal path of the encoder, where the backward signal path of the encoder corresponds The signal path for the decoder (see decoder 30 in FIG. 3).
  • the encoder 20 receives a picture 201 or an image block 203 of the picture 201 through, for example, an input 202, for example, a picture in a picture sequence forming a video or a video sequence.
  • the image block 203 may also be referred to as a current picture block or a picture block to be coded
  • the picture 201 may be referred to as a current picture or a picture to be coded (especially when the current picture is distinguished from other pictures in video coding, other pictures such as the same video sequence That is, the previously encoded and/or decoded pictures in the video sequence of the current picture are also included).
  • An embodiment of the encoder 20 may include a segmentation unit (not shown in FIG. 2) for segmenting the picture 201 into a plurality of blocks such as image blocks 203, usually into a plurality of non-overlapping blocks.
  • the segmentation unit can be used to use the same block size and corresponding grids that define the block size for all pictures in the video sequence, or to change the block size between pictures or subsets or picture groups, and divide each picture into The corresponding block.
  • the prediction processing unit 260 of the encoder 20 may be used to perform any combination of the above-mentioned segmentation techniques.
  • image block 203 is also or can be regarded as a two-dimensional array or matrix of sampling points with sample values, although its size is smaller than picture 201.
  • the image block 203 may include, for example, one sampling array (for example, the brightness array in the case of black and white pictures 201) or three sampling arrays (for example, one brightness array and two chromaticity arrays in the case of color pictures) or An array of any other number and/or category depending on the color format applied.
  • the number of sampling points in the horizontal and vertical directions (or axes) of the image block 203 defines the size of the image block 203.
  • the encoder 20 shown in FIG. 2 is used to encode the picture 201 block by block, for example, to perform encoding and prediction on each image block 203.
  • the residual calculation unit 204 is used to calculate the residual block 205 based on the picture image block 203 and the prediction block 265 (other details of the prediction block 265 are provided below), for example, by subtracting the sample value of the picture image block 203 sample by sample (pixel by pixel) The sample values of the block 265 are depredicted to obtain the residual block 205 in the sample domain.
  • the transform processing unit 206 is used to apply a transform such as discrete cosine transform (DCT) or discrete sine transform (DST) to the sample values of the residual block 205 to obtain transform coefficients 207 in the transform domain .
  • the transform coefficient 207 may also be called a transform residual coefficient, and represents a residual block 205 in the transform domain.
  • the transform processing unit 206 may be used to apply integer approximations of DCT/DST, such as the transform specified by HEVC/H.265. Compared with the orthogonal DCT transform, this integer approximation is usually scaled by a factor. In order to maintain the norm of the residual block processed by the forward and inverse transform, an additional scaling factor is applied as part of the transform process.
  • the scaling factor is usually selected based on certain constraints, for example, the scaling factor is a power of two used for the shift operation, the bit depth of the transform coefficient, the accuracy, and the trade-off between implementation cost, and so on.
  • a specific scaling factor can be specified for the inverse transform by the inverse transform processing unit 212 on the decoder 30 side (and a corresponding inverse transform by the inverse transform processing unit 212 on the encoder 20 side), and accordingly, The 20 side specifies the corresponding scaling factor for the positive transform by the transform processing unit 206.
  • the quantization unit 208 is used to quantize the transform coefficient 207 by, for example, applying scalar quantization or vector quantization to obtain the quantized transform coefficient 209.
  • the quantized transform coefficient 209 may also be referred to as the quantized residual coefficient 209.
  • the quantization process can reduce the bit depth associated with some or all of the transform coefficients 207. For example, n-bit transform coefficients can be rounded down to m-bit transform coefficients during quantization, where n is greater than m.
  • the degree of quantization can be modified by adjusting quantization parameters (QP). For example, for scalar quantization, different scales can be applied to achieve thinner or coarser quantization.
  • QP quantization parameters
  • a smaller quantization step size corresponds to a finer quantization
  • a larger quantization step size corresponds to a coarser quantization.
  • a suitable quantization step size can be indicated by a quantization parameter (QP).
  • the quantization parameter may be an index of a predefined set of suitable quantization steps.
  • smaller quantization parameters may correspond to fine quantization (smaller quantization step size)
  • larger quantization parameters may correspond to coarse quantization (larger quantization step size)
  • the quantization may include dividing by the quantization step size and the corresponding quantization or inverse quantization performed by, for example, inverse quantization 210, or may include multiplying the quantization step size.
  • Embodiments according to some standards such as HEVC may use quantization parameters to determine the quantization step size.
  • the quantization step size can be calculated based on the quantization parameter using a fixed-point approximation including an equation of division. Additional scaling factors can be introduced for quantization and inverse quantization to restore the norm of the residual block that may be modified due to the scale used in fixed-point approximation of the equations for quantization step size and quantization parameter.
  • the scale of inverse transform and inverse quantization may be combined.
  • a custom quantization table can be used and signaled from the encoder to the decoder in a bitstream, for example. Quantization is a lossy operation, where the larger the quantization step, the greater the loss.
  • the inverse quantization unit 210 is used to apply the inverse quantization of the quantization unit 208 on the quantized coefficients to obtain the inverse quantized coefficients 211, for example, based on or using the same quantization step size as the quantization unit 208, apply the quantization scheme applied by the quantization unit 208 Inverse quantization scheme.
  • the inverse quantized coefficient 211 may also be referred to as an inverse quantized residual coefficient 211, which corresponds to the transform coefficient 207, although the loss due to quantization is usually not the same as the transform coefficient.
  • the inverse transform processing unit 212 is used to apply the inverse transform of the transform applied by the transform processing unit 206, for example, an inverse discrete cosine transform (DCT) or an inverse discrete sine transform (DST), in the sample domain
  • the inverse transform block 213 is obtained.
  • the inverse transform block 213 may also be referred to as an inverse transform dequantized block 213 or an inverse transform residual block 213.
  • the reconstruction unit 214 (eg, summer 214) is used to add the inverse transform block 213 (ie, the reconstructed residual block 213) to the prediction block 265 to obtain the reconstructed block 215 in the sample domain, for example, The sample values of the reconstructed residual block 213 and the sample values of the prediction block 265 are added.
  • a buffer unit 216 (or simply "buffer" 216), such as a line buffer 216, is used to buffer or store the reconstructed block 215 and corresponding sample values for, for example, intra prediction.
  • the encoder may be used to use the unfiltered reconstructed blocks and/or corresponding sample values stored in the buffer unit 216 for any type of estimation and/or prediction, such as intra prediction.
  • an embodiment of the encoder 20 may be configured such that the buffer unit 216 is used not only to store the reconstructed block 215 for intra prediction 254, but also for the loop filter unit 220 (not shown in FIG. 2) Out), and/or, for example, causing the buffer unit 216 and the decoded picture buffer unit 230 to form a buffer.
  • Other embodiments may be used to use the filtered block 221 and/or blocks or samples from the decoded picture buffer 230 (neither shown in FIG. 2) as an input or basis for intra prediction 254.
  • the decoded picture buffer 230 is also used to store knowledge base images. For the detailed description of the knowledge base, it will not be repeated here.
  • the loop filter unit 220 (or simply “loop filter” 220) is used to filter the reconstructed block 215 to obtain the filtered block 221, so as to smoothly perform pixel conversion or improve video quality.
  • the loop filter unit 220 is intended to represent one or more loop filters, such as deblocking filters, sample-adaptive offset (SAO) filters, or other filters, such as bilateral filters, self-adaptive filters Adaptive loop filter (adaptive loop filter, ALF), or sharpening or smoothing filter, or collaborative filter.
  • the loop filter unit 220 is shown as an in-loop filter in FIG. 2, in other configurations, the loop filter unit 220 may be implemented as a post-loop filter.
  • the filtered block 221 may also be referred to as the filtered reconstructed block 221.
  • the decoded picture buffer 230 may store the reconstructed coding block after the loop filter unit 220 performs a filtering operation on the reconstructed coding block.
  • Embodiments of the encoder 20 may be used to output loop filter parameters (eg, sample adaptive offset information), for example, directly output or by the entropy encoding unit 270 or any other
  • the entropy coding unit outputs after entropy coding, for example, so that the decoder 30 can receive and apply the same loop filter parameters for decoding.
  • the decoded picture buffer (DPB) 230 may be a reference picture memory for storing reference picture data for the encoder 20 to encode video data.
  • DPB 230 can be formed by any of a variety of memory devices, such as dynamic random access memory (dynamic random access (DRAM) (including synchronous DRAM (synchronous DRAM, SDRAM), magnetoresistive RAM (magnetoresistive RAM, MRAM), resistive RAM (resistive RAM, RRAM)) or other types of memory devices.
  • DRAM dynamic random access
  • the DPB 230 and the buffer 216 may be provided by the same memory device or separate memory devices.
  • a decoded picture buffer (DPB) 230 is used to store the filtered block 221.
  • the decoded picture buffer 230 may be further used to store other previous filtered blocks of the same current picture or different pictures such as previous reconstructed pictures, such as the previously reconstructed and filtered block 221, and may provide the complete previous The reconstructed ie decoded pictures (and corresponding reference blocks and samples) and/or partially reconstructed current pictures (and corresponding reference blocks and samples), for example for inter prediction.
  • a decoded picture buffer (DPB) 230 is used to store the reconstructed block 215.
  • the prediction processing unit 260 also known as the block prediction processing unit 260, is used to receive or acquire the image block 203 (current image block 203 of the current picture 201) and reconstructed picture data, such as the same (current) picture from the buffer 216 Reference samples and/or reference picture data 231 of one or more previously decoded pictures from the decoded picture buffer 230, and used to process such data for prediction, that is, to provide an inter prediction block 245 or The prediction block 265 of the intra prediction block 255.
  • the mode selection unit 262 may be used to select a prediction mode (eg, intra or inter prediction mode) and/or the corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.
  • a prediction mode eg, intra or inter prediction mode
  • the corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.
  • An embodiment of the mode selection unit 262 may be used to select a prediction mode (for example, from those prediction modes supported by the prediction processing unit 260), which provides the best match or the minimum residual (the minimum residual means Better compression in transmission or storage), or provide minimum signaling overhead (minimum signaling overhead means better compression in transmission or storage), or consider or balance both at the same time.
  • the mode selection unit 262 may be used to determine a prediction mode based on rate distortion optimization (RDO), that is, to select a prediction mode that provides minimum bit rate distortion optimization, or to select a prediction mode in which the related rate distortion at least meets the prediction mode selection criteria .
  • RDO rate distortion optimization
  • the encoder 20 is used to determine or select the best or optimal prediction mode from the (predetermined) prediction mode set.
  • the set of prediction modes may include, for example, intra prediction modes and/or inter prediction modes.
  • the intra prediction mode set may include 35 different intra prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in H.265, or may include 67 Different intra prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in the developing H.266.
  • non-directional modes such as DC (or mean) mode and planar mode
  • directional modes as defined in the developing H.266.
  • the set of inter prediction modes depends on the available reference pictures (ie, for example, the aforementioned at least partially decoded pictures stored in DBP 230) and other inter prediction parameters, for example, depending on whether the entire reference picture is used or only Use a part of the reference picture, for example the search window area surrounding the area of the current block, to search for the best matching reference block, and/or for example depending on whether pixel interpolation such as half-pixel and/or quarter-pixel interpolation is applied
  • the set of inter prediction modes may include advanced motion vector (Advanced Motion Vector Prediction, AMVP) mode and merge mode.
  • AMVP Advanced Motion Vector Prediction
  • the set of inter prediction modes may include an improved control point-based AMVP mode according to an embodiment of the present invention, and an improved control point-based merge mode.
  • the intra prediction unit 254 may be used to perform any combination of inter prediction techniques described below.
  • the embodiments of the present invention may also apply skip mode and/or direct mode.
  • the prediction processing unit 260 may be further used to split the image block 203 into smaller block partitions or sub-blocks, for example, iteratively using quad-tree (QT) segmentation, binary-tree (BT) segmentation Or triple-tree (TT) partitioning, or any combination thereof, and for performing predictions for each of block partitions or sub-blocks, for example, where mode selection includes selecting the tree structure of the divided image block 203 and selecting applications The prediction mode for each of the block partitions or sub-blocks.
  • QT quad-tree
  • BT binary-tree
  • TT triple-tree
  • the inter prediction unit 244 may include a motion estimation (ME) unit (not shown in FIG. 2) and a motion compensation (MC) unit (not shown in FIG. 2).
  • the motion estimation unit is used to receive or acquire a picture image block 203 (current picture image block 203 of the current picture 201) and a decoded picture 231, or at least one or more previously reconstructed blocks, for example, one or more other/different
  • the reconstructed block of the previously decoded picture 231 is used for motion estimation.
  • the video sequence may include the current picture and the previously decoded picture 31, or in other words, the current picture and the previously decoded picture 31 may be part of or form a sequence of pictures that form the video sequence.
  • the encoder 20 may be used to select a reference block from multiple reference blocks of the same or different pictures in multiple other pictures, and provide a reference picture and/or provide a reference to a motion estimation unit (not shown in FIG. 2)
  • the offset (spatial offset) between the position of the block (X, Y coordinates) and the position of the current block is used as an inter prediction parameter. This offset is also called motion vector (MV).
  • the motion compensation unit is used to acquire inter prediction parameters and perform inter prediction based on or using inter prediction parameters to obtain inter prediction blocks 245.
  • the motion compensation performed by the motion compensation unit may include extracting or generating a prediction block based on a motion/block vector determined by motion estimation (possibly performing interpolation of sub-pixel accuracy). Interpolation filtering can generate additional pixel samples from known pixel samples, potentially increasing the number of candidate prediction blocks that can be used to encode picture blocks.
  • the motion compensation unit 246 may locate the prediction block pointed to by the motion vector in a reference picture list. Motion compensation unit 246 may also generate syntax elements associated with blocks and video slices for use by decoder 30 when decoding picture blocks of video slices.
  • the above inter prediction unit 244 may transmit a syntax element to the entropy encoding unit 270, where the syntax element includes inter prediction parameters (such as an inter prediction mode selected for the current block prediction after traversing multiple inter prediction modes Instructions).
  • inter prediction parameters such as an inter prediction mode selected for the current block prediction after traversing multiple inter prediction modes Instructions.
  • the decoding terminal 30 may directly use the default prediction mode for decoding. It can be understood that the inter prediction unit 244 may be used to perform any combination of inter prediction techniques.
  • the intra prediction unit 254 is used to acquire, for example, a picture block 203 (current picture block) that receives the same picture and one or more previously reconstructed blocks, such as reconstructed neighboring blocks, for intra estimation.
  • the encoder 20 may be used to select an intra prediction mode from a plurality of (predetermined) intra prediction modes.
  • Embodiments of the encoder 20 may be used to select an intra prediction mode based on optimization criteria, for example, based on a minimum residual (eg, an intra prediction mode that provides the prediction block 255 most similar to the current picture block 203) or minimum rate distortion.
  • a minimum residual eg, an intra prediction mode that provides the prediction block 255 most similar to the current picture block 203
  • minimum rate distortion e.g., a minimum rate distortion
  • the intra prediction unit 254 is further used to determine the intra prediction block 255 based on the intra prediction parameters of the intra prediction mode as selected. In any case, after selecting the intra-prediction mode for the block, the intra-prediction unit 254 is also used to provide the intra-prediction parameters to the entropy encoding unit 270, that is, to provide an indication of the selected intra-prediction mode for the block Information. In one example, the intra prediction unit 254 may be used to perform any combination of intra prediction techniques.
  • the above-mentioned intra-prediction unit 254 may transmit a syntax element to the entropy encoding unit 270, where the syntax element includes intra-prediction parameters (such as the intra-prediction mode selected for the current block prediction after traversing multiple intra-prediction modes) Instructions).
  • the intra prediction parameters may not be carried in the syntax element.
  • the decoding terminal 30 may directly use the default prediction mode for decoding.
  • the entropy coding unit 270 is used to convert the entropy coding algorithm or scheme (for example, variable length coding (VLC) scheme, context adaptive VLC (context adaptive VLC, CAVLC) scheme, arithmetic coding scheme, context adaptive binary arithmetic) Encoding (context adaptive) binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval entropy (probability interval interpartitioning entropy, PIPE) encoding or other entropy Coding method or technique) applied to a single or all of the quantized residual coefficients 209, inter prediction parameters, intra prediction parameters, and/or loop filter parameters (or not applied) to obtain the output 272 to For example, the encoded picture data 21 output in the form of an encoded bit stream 21.
  • VLC variable length coding
  • CABAC context adaptive binary arithmetic
  • SBAC syntax-based context-adaptive binary arithmetic coding
  • the encoded bitstream can be transmitted to the video decoder 30 or archived for later transmission or retrieval by the video decoder 30.
  • the entropy encoding unit 270 may also be used to entropy encode other syntax elements of the current video slice being encoded.
  • the code stream encapsulating unit 280 is used to encode information related to determining how to refer to the knowledge base image for decoding the current image to be processed when the knowledge base image referenced by the current image to be processed and the current image to be processed are the same image ( For example, the first logo, the second logo, the third logo, etc.) are encoded into the code stream (main code stream) and output directly through output 272.
  • the current image will be output to the residual calculation unit 204.
  • video encoder 20 may be used to encode video streams.
  • the non-transform based encoder 20 may directly quantize the residual signal without the transform processing unit 206 for certain blocks or frames.
  • the encoder 20 may have a quantization unit 208 and an inverse quantization unit 210 combined into a single unit.
  • the encoder 20 may be used to implement the codec method described in the following embodiments.
  • the video encoder 20 can directly quantize the residual signal without processing by the transform processing unit 206, and accordingly, without processing by the inverse transform processing unit 212; or, for some For image blocks or image frames, the video encoder 20 does not generate residual data, and accordingly does not need to be processed by the transform processing unit 206, quantization unit 208, inverse quantization unit 210, and inverse transform processing unit 212; or, the video encoder 20 may convert The reconstructed image block is directly stored as a reference block without being processed by the filter 220; alternatively, the quantization unit 208 and the inverse quantization unit 210 in the video encoder 20 may be merged together.
  • the loop filter 220 is optional, and in the case of lossless compression encoding, the transform processing unit 206, quantization unit 208, inverse quantization unit 210, and inverse transform processing unit 212 are optional. It should be understood that the inter prediction unit 244 and the intra prediction unit 254 may be selectively enabled according to different application scenarios.
  • FIG. 3 shows a schematic/conceptual block diagram of an example of a decoder 30 for implementing an embodiment of the present invention.
  • the video decoder 30 is used to receive encoded picture data (eg, encoded bitstream) 21, for example, encoded by the encoder 20, to obtain the decoded picture 231.
  • encoded picture data eg, encoded bitstream
  • video decoder 30 receives video data from video encoder 20, such as an encoded video bitstream and associated syntax elements representing picture blocks of the encoded video slice.
  • the decoder 30 includes an entropy decoding unit 304, an inverse quantization unit 310, an inverse transform processing unit 312, a reconstruction unit 314 (such as a summer 314), a buffer 316, a loop filter 320, a The decoded picture buffer 330 and the prediction processing unit 360.
  • the prediction processing unit 360 may include an inter prediction unit 344, an intra prediction unit 354, and a mode selection unit 362.
  • video decoder 30 may perform a decoding pass that is generally inverse to the encoding pass described with reference to video encoder 20 of FIG. 2.
  • the entropy decoding unit 304 is used to perform entropy decoding on the encoded picture data 21 to obtain, for example, quantized coefficients 309 and/or decoded encoding parameters (not shown in FIG. 3), for example, inter prediction, intra prediction parameters , Any or all of the loop filter parameters and/or other syntax elements (decoded).
  • the entropy decoding unit 304 is further used to forward inter prediction parameters, intra prediction parameters, and/or other syntax elements to the prediction processing unit 360.
  • Video decoder 30 may receive syntax elements at the video slice level and/or the video block level.
  • the inverse quantization unit 310 may be functionally the same as the inverse quantization unit 110
  • the inverse transform processing unit 312 may be functionally the same as the inverse transform processing unit 212
  • the reconstruction unit 314 may be functionally the same as the reconstruction unit 214
  • the buffer 316 may be functionally
  • the loop filter 320 may be functionally the same as the loop filter 220
  • the decoded picture buffer 330 may be functionally the same as the decoded picture buffer 230.
  • the prediction processing unit 360 may include an inter prediction unit 344 and an intra prediction unit 354, where the inter prediction unit 344 may be similar in function to the inter prediction unit 244, and the intra prediction unit 354 may be similar in function to the intra prediction unit 254 .
  • the prediction processing unit 360 is generally used to perform block prediction and/or obtain the prediction block 365 from the encoded data 21, and to receive or obtain prediction-related parameters and/or information about the entropy decoding unit 304 (explicitly or implicitly). Information about the selected prediction mode.
  • the intra prediction unit 354 of the prediction processing unit 360 is used to signal-based the intra prediction mode and the previous decoded block from the current frame or picture Data to generate a prediction block 365 for the picture block of the current video slice.
  • the inter prediction unit 344 eg, motion compensation unit
  • Other syntax elements generate a prediction block 365 for the video block of the current video slice.
  • a prediction block may be generated from a reference picture in a reference picture list.
  • the video decoder 30 may construct the reference frame lists: list 0 and list 1 based on the reference pictures stored in the DPB 330 using default construction techniques.
  • the prediction processing unit 360 is used to determine the prediction information for the video block of the current video slice by parsing the motion vector and other syntax elements, and use the prediction information to generate the prediction block for the current video block being decoded.
  • the prediction processing unit 360 uses some received syntax elements to determine the prediction mode (e.g., intra or inter prediction) of the video block used to encode the video slice, and the inter prediction slice type ( For example, B slice, P slice, or GPB slice), construction information for one or more of the reference picture lists for slices, motion vectors for each inter-coded video block for slices, The inter prediction status and other information of each inter-coded video block of the slice to decode the video block of the current video slice.
  • the prediction mode e.g., intra or inter prediction
  • the inter prediction slice type For example, B slice, P slice, or GPB slice
  • the syntax elements received by the video decoder 30 from the bitstream include an adaptive parameter set (adaptive parameter set, APS), a sequence parameter set (SPS), and a picture parameter set (picture parameter (set, PPS) or the syntax element in one or more of the stripe headers.
  • an adaptive parameter set adaptive parameter set
  • SPS sequence parameter set
  • PPS picture parameter set
  • the inverse quantization unit 310 may be used to inverse quantize (ie, inverse quantize) the quantized transform coefficients provided in the bitstream and decoded by the entropy decoding unit 304.
  • the inverse quantization process may include using the quantization parameters calculated by the video encoder 20 for each video block in the video slice to determine the degree of quantization that should be applied and also determine the degree of inverse quantization that should be applied.
  • the inverse transform processing unit 312 is used to apply an inverse transform (eg, inverse DCT, inverse integer transform, or conceptually similar inverse transform process) to the transform coefficients to generate a residual block in the pixel domain.
  • an inverse transform eg, inverse DCT, inverse integer transform, or conceptually similar inverse transform process
  • the reconstruction unit 314 (eg, summer 314) is used to add the inverse transform block 313 (ie, the reconstructed residual block 313) to the prediction block 365 to obtain the reconstructed block 315 in the sample domain, for example by The sample values of the reconstructed residual block 313 and the sample values of the prediction block 365 are added.
  • the loop filter unit 320 (during the encoding cycle or after the encoding cycle) is used to filter the reconstructed block 315 to obtain the filtered block 321 to smoothly perform pixel conversion or improve video quality.
  • the loop filter unit 320 may be used to perform any combination of filtering techniques described below.
  • the loop filter unit 320 is intended to represent one or more loop filters, such as deblocking filters, sample-adaptive offset (SAO) filters, or other filters, such as bilateral filters, Adaptive loop filter (adaptive loop filter, ALF), or sharpening or smoothing filter, or collaborative filter.
  • the loop filter unit 320 is shown as an in-loop filter in FIG. 3, in other configurations, the loop filter unit 320 may be implemented as a post-loop filter.
  • the decoded video block 321 in a given frame or picture is then stored in a decoded picture buffer 330 that stores reference pictures for subsequent motion compensation.
  • the decoded picture buffer 330 is also used to store knowledge base images.
  • the code stream analysis unit 303 analyzes the coding information related to the referenced knowledge base image in the main code stream in the knowledge base-based coding method. When it is determined that the current image to be processed and the reference knowledge base image are the same image, the decoding operation of the image to be processed may not be performed, and the decoding information of the copied knowledge base image is output through output 332.
  • the decoder 30 is used, for example, to output the decoded picture 31 through the output 332 for presentation to the user or for the user to view.
  • video decoder 30 may be used to decode the compressed bitstream.
  • the decoder 30 may generate the output video stream without the loop filter unit 320.
  • the non-transform based decoder 30 may directly inversely quantize the residual signal without the inverse transform processing unit 312 for certain blocks or frames.
  • the video decoder 30 may have an inverse quantization unit 310 and an inverse transform processing unit 312 combined into a single unit.
  • the decoder 30 is used to implement the codec method described in the embodiment below.
  • video decoder 30 may be used to decode the encoded video bitstream.
  • the video decoder 30 may generate an output video stream without processing by the filter 320; or, for some image blocks or image frames, the entropy decoding unit 304 of the video decoder 30 does not decode the quantized coefficients, and accordingly does not It needs to be processed by the inverse quantization unit 310 and the inverse transform processing unit 312.
  • the loop filter 320 is optional; and for lossless compression, the inverse quantization unit 310 and the inverse transform processing unit 312 are optional.
  • the inter prediction unit and the intra prediction unit may be selectively enabled.
  • the processing results for a certain link can be further processed and output to the next link, for example, in interpolation filtering, motion vector derivation or loop filtering, etc. After the link, the results of the corresponding link are further clipped or shift shifted.
  • the motion vectors of the control points of the current image block derived from the motion vectors of adjacent affine coding blocks, or the motion vectors of the sub-blocks of the current image block derived may be further processed, and this application does not do this limited.
  • the value range of the motion vector is constrained to be within a certain bit width. Assuming that the allowed bit width of the motion vector is bitDepth, the range of the motion vector is -2 ⁇ (bitDepth-1) ⁇ 2 ⁇ (bitDepth-1)-1, where the " ⁇ " symbol indicates a power. If bitDepth is 16, the value ranges from -32768 to 32767. If bitDepth is 18, the value ranges from -131072 to 131071.
  • the values of the motion vectors are constrained so that the maximum difference between the integer parts of the four 4x4 sub-blocks MV does not exceed N pixels, for example no more than one pixel.
  • ux (vx+2 bitDepth )%2 bitDepth
  • vx is the horizontal component of the motion vector of the image block or the sub-block of the image block
  • vy is the vertical component of the motion vector of the image block or the sub-block of the image block
  • ux and uy are intermediate values
  • bitDepth represents the bit width
  • the value of vx is -32769, and 32767 is obtained by the above formula. Because in the computer, the value is stored in the form of two's complement, the complement of -32769 is 1,0111,1111,1111,1111 (17 bits), the computer handles the overflow as discarding the high bit, then the value of vx If it is 0111,1111,1111,1111, it is 32767, which is consistent with the result obtained by formula processing.
  • vx Clip3(-2 bitDepth-1 ,2 bitDepth-1 -1,vx)
  • vx is the horizontal component of the motion vector of the image block or the sub-block of the image block
  • vy is the vertical component of the motion vector of the image block or the sub-block of the image block
  • x, y, and z respectively correspond to the MV clamp
  • FIG. 4 is a schematic structural diagram of a video decoding device 400 (for example, a video encoding device 400 or a video decoding device 400) provided by an embodiment of the present invention.
  • the video coding device 400 is suitable for implementing the embodiments described herein.
  • the video coding device 400 may be a video decoder (eg, decoder 30 of FIG. 1A) or a video encoder (eg, encoder 20 of FIG. 1A).
  • the video decoding device 400 may be one or more components in the decoder 30 of FIG. 1A or the encoder 20 of FIG. 1A described above.
  • the video decoding device 400 includes: an inlet port 410 for receiving data and a receiving unit (Rx) 420, a processor for processing data, a logic unit or a central processing unit (CPU) 430, and a transmitter unit for transmitting data (Tx) 440 and exit port 450, and a memory 460 for storing data.
  • the video decoding device 400 may further include a photoelectric conversion component and an electro-optical (EO) component coupled to the inlet port 410, the receiver unit 420, the transmitter unit 440, and the outlet port 450 for the outlet or inlet of the optical signal or the electrical signal.
  • EO electro-optical
  • the processor 430 is implemented by hardware and software.
  • the processor 430 may be implemented as one or more CPU chips, cores (eg, multi-core processors), FPGA, ASIC, and DSP.
  • the processor 430 communicates with the inlet port 410, the receiver unit 420, the transmitter unit 440, the outlet port 450, and the memory 460.
  • the processor 430 includes a decoding module 470 (for example, an encoding module 470 or a decoding module 470).
  • the encoding/decoding module 470 implements the embodiments disclosed herein to implement the chroma block prediction method provided by the embodiments of the present invention. For example, the encoding/decoding module 470 implements, processes, or provides various encoding operations.
  • the encoding/decoding module 470 provides a substantial improvement in the function of the video decoding device 400 and affects the conversion of the video decoding device 400 to different states.
  • the encoding/decoding module 470 is implemented with instructions stored in the memory 460 and executed by the processor 430.
  • the memory 460 includes one or more magnetic disks, tape drives, and solid-state drives, and can be used as an overflow data storage device for storing programs when these programs are selectively executed, as well as instructions and data read during program execution.
  • the memory 460 may be volatile and/or non-volatile, and may be read only memory (ROM), random access memory (RAM), random access memory (ternary content-addressable memory (TCAM), and/or static Random Access Memory (SRAM).
  • FIG. 5 is a simplified block diagram of an apparatus 500 that can be used as either or both of the source device 12 and the destination device 14 in FIG. 1A according to an exemplary embodiment.
  • the device 500 can implement the technology of the present application.
  • FIG. 5 is a schematic block diagram of an implementation manner of an encoding device or a decoding device (referred to simply as a decoding device 500) according to an embodiment of the present application.
  • the decoding device 500 may include a processor 510, a memory 530, and a bus system 550.
  • the processor and the memory are connected through a bus system, the memory is used to store instructions, and the processor is used to execute the instructions stored in the memory.
  • the memory of the decoding device stores the program code
  • the processor can call the program code stored in the memory to perform various video encoding or decoding methods described in this application, especially various new encoding and decoding methods. In order to avoid repetition, they are not described in detail here.
  • the processor 510 may be a central processing unit (Central Processing Unit, referred to as "CPU"), and the processor 510 may also be other general-purpose processors, digital signal processors (DSPs), dedicated integrated Circuit (ASIC), ready-made programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
  • the general-purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
  • the memory 530 may include a read-only memory (ROM) device or a random access memory (RAM) device. Any other suitable type of storage device may also be used as the memory 530.
  • the memory 530 may include code and data 531 accessed by the processor 510 using the bus 550.
  • the memory 530 may further include an operating system 533 and an application program 535 including at least one program that allows the processor 510 to perform the video encoding or decoding method described in the present application (especially the codec method described in the present application).
  • the application program 535 may include applications 1 to N, which further include a video encoding or decoding application (referred to as a video decoding application) that performs the video encoding or decoding method described in this application.
  • the bus system 550 may also include a power bus, a control bus, and a status signal bus. However, for clarity, various buses are marked as the bus system 550 in the figure.
  • the decoding device 500 may also include one or more output devices, such as a display 570.
  • the display 570 may be a tactile display that merges the display with a tactile unit that operably senses touch input.
  • the display 570 may be connected to the processor 510 via the bus 550.
  • a video sequence in order to enable the encoded video sequence to support the random access function, the video sequence is divided into a plurality of fragments with random access function (referred to as random access fragments).
  • a video sequence includes at least one random access segment, and each random access segment includes one random access image and multiple non-random access images.
  • an image in a random access segment can be intra-coded, or, inter-coded with reference to other images in a video sequence using inter-frame prediction.
  • the knowledge base encoding scheme introduces a knowledge base image (or knowledge image for short).
  • the knowledge base image is the random access to which the current image in the random access segment belongs
  • the database storing the above-mentioned collection of knowledge base images may be called a knowledge base.
  • a method of encoding and decoding an image in this video with reference to at least one knowledge base image may be called knowledge base-based video encoding (English: library-based video encoding).
  • the knowledge base image combines multiple random access fragments with relevant information within a large time span, eliminating redundant information between multiple random access fragments.
  • the image that provides random access capability can also refer to the knowledge base image.
  • this article refers to such referenced knowledge base images as reference knowledge base (Reference Library, RL) images, which provide random access capabilities when knowledge base images are available.
  • Reference picture set (reference picture set, rps)
  • the reference image set may be composed of related information of the image referred to by the current image to be processed.
  • the reference image set may include information of referenced non-knowledge base images, and may also include information of knowledge base images.
  • the current image to be processed may refer to the knowledge base image using a knowledge base-based video encoding and decoding method.
  • the reference image set may also be referred to as a reference configuration set (reference configure set, rcs).
  • the rcs may include the number of reference images, and the number of the knowledge base image in the reference images included in the reference configuration set. For example, rcs indicates whether the ith image is a knowledge base image, the number of the ith image, etc.
  • FIG. 6 shows a reference relationship between a random access segment to which a main stream image obtained by a video encoding method used in a knowledge base belongs to a knowledge base image, and each knowledge image is accessed by at least two discrete random Refer to the clip.
  • the reference image is intra-coded to obtain encoded data of the reference image.
  • the reconstructed image of the reference image is reconstructed, and the reconstructed image of the reference image is inter-coded to the image to be processed, thereby obtaining the encoded data of the image to be processed.
  • the code stream data of the reference image is sent to the decoding end as a knowledge layer code stream. Send the code stream data of the image to be processed as the main code stream to the decoding end.
  • the decoding end After receiving the main code stream of the current image to be processed, the decoding end determines the image in the reference knowledge base image set as a reference image, reconstructs the reference knowledge base image, and inter-frame decodes the image to be processed based on the reconstructed knowledge base image Get the reconstructed pixel value of the image to be processed.
  • the to-be-processed image of the main stream if the to-be-processed image refers to a certain knowledge base image in the knowledge base, you need to decode the knowledge base image in the knowledge layer code stream before you can decode the pending image in the main stream Process the image.
  • the knowledge base image may be an image in a to-be-processed video sequence, and of course the acquired knowledge base image may also be an image synthesized by an image modeled in the to-be-processed video sequence and an image in the to-be-processed video sequence. That is to say, the reference knowledge base image selected for the current image to be processed may be the same image as the current image to be processed. In this case, after encoding and decoding the reference knowledge base image, there is actually no need to add additional code The image to be processed in the main stream is decoded.
  • the referenced knowledge base image selected for the current image to be processed may be the same image as the current image to be processed In this case, after encoding and decoding the reference knowledge base image, there is redundancy in the way of additionally encoding and decoding the image to be processed in the main code stream.
  • this application proposes a video image encoding and decoding method and device.
  • the reference knowledge base image selected for the current image to be processed may be the same image as the current image to be processed, the reference is encoded and decoded After the knowledge base image of, no longer additional coding and decoding of the image to be processed in the main stream, but to determine the decoded data of the image to be processed in the main stream based on the decoded data of the knowledge base image referenced by the simple copy reference, which can be avoided
  • the existing redundant coding method saves transmission resources.
  • the method and the device are based on the same inventive concept. Since the principles of the method and the device to solve the problem are similar, the implementation of the device and the method can be referred to each other, and the repetition is not repeated here.
  • At least one item (a) in a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be a single or multiple .
  • the encoder when encoding (or decoding) an image, the encoder (or decoder) can select the current encoded image (or Decoded images) Images with similar texture content are used as reference images.
  • This reference image is called a knowledge base image, and the database that stores the collection of reference images is called a knowledge base. At least one image in this video refers to at least one knowledge base image.
  • the method of encoding and decoding is called video encoding based on knowledge base (English: library-based video encoding).
  • Encoding a video sequence using knowledge-based video coding will generate a knowledge layer code stream containing the knowledge base image coding code stream and a video layer code stream containing the code stream obtained by referring to the knowledge base image coding for each frame image of the video sequence .
  • These two code streams are similar to the basic layer code stream and the enhancement layer code stream generated by scalable video coding (SVC), that is, the sequence layer code stream depends on the knowledge layer code stream.
  • SVC scalable video coding
  • the dependency relationship between the dual-stream organization of video coding based on the knowledge base and the hierarchical stream of SVC's hierarchical stream organization is different. The difference is that the dual-stream hierarchy of SVC is based on certain The alignment time period is dependent, and the video layer-dependent knowledge layer in the dual code stream based on knowledge-based video coding is dependent on the non-aligned time period.
  • two code streams are obtained, the knowledge base code stream and the video main code stream, and the decoding of the video main code stream must rely on the knowledge base code stream.
  • the frame in the knowledge base code stream needs to be decoded before the video frame in the main stream can be decoded.
  • a decoding peak will be generated, which will have a decoding impact on the decoder.
  • library_picture_enable_flag 1-bit identifier. When the value is 1, it means that the current code stream refers to the external knowledge layer code stream; when the value is 0, it means that the current code stream does not refer to the knowledge layer code stream.
  • the number of bits in this field and the values representing different meanings can be freely defined and designed, and are not limited in the present invention.
  • min_library_interval_time 12 bits. Describe the minimum decoding time interval of the knowledge image referenced by the current bitstream, and its value range is limited by profile and level. Among them, the upper 6 bits describe the value between 0 and 59 in seconds, and the lower 6 bits describe the value between 0 and 63. When the frame rate is less than 64, the unit is the image, otherwise, the unit is 1/64 second.
  • the semantics of min_library_interval_time may be: fixed bit length or variable bit length symbols, describing the minimum decoding time interval of the knowledge image referenced by the current bitstream, for example, each bit of the syntax element describes time division Seconds, for example, the syntax element describes the number of units in seconds, and for example, the syntax element describes the number of units in images, the value range is limited by the profile and level, where different profiles and levels can determine the minimum decoding time interval The lower limit of the value range.
  • the encoder side may perform the following operations:
  • set L includes all the knowledge images that can be used by the entire main stream; initialization
  • the encoding time tj of the previous (previous) reference main stream image of the new knowledge image (the previous one here is determined according to the encoding timing) is T, and its initialization value should ensure that the first main stream image of the encoding ( The encoding time is 0 seconds)
  • Any knowledge image can be used as a candidate reference image (for example, no more than -k seconds, so that the difference between the encoding time 0 and T of the first main stream image is not less than k seconds), the value of k seconds
  • the domain range and the range of the number of images that can be decoded in k seconds fk+N that is, the maximum number of images that can be decoded more than the number of images in the main stream fk is N) can be limited by profile and
  • min_library_interval_time is equal to the value of k
  • min_library_interval_time is equal to the value of k-1 to ensure that the value of min_library_interval_time starts from 0,
  • min_library_interval_time is equal to the value of log2(k) to reduce the number of bits occupied by min_library_interval_time
  • any image has a corresponding field indicating whether the image refers to the knowledge image, for example, this field can be the field of the image, or it can be the default inherited from other images allowed by the standard Field; this step can use existing technical means, which will not be repeated in the present invention), perform one of the following operations:
  • the above operation method of selecting a knowledge image includes but is not limited to:
  • the above operation method of selecting a knowledge image includes but is not limited to:
  • the knowledge images in the set L have been reconstructed, but the knowledge images that are not in the set L are not reconstructed or need to be reconstructed, wherein the newly reconstructed knowledge images satisfy one or more of the following conditions:
  • the knowledge image that has been reconstructed is destroyed due to an error in the cache content; or,
  • the knowledge image that has been reconstructed is deleted or replaced due to a management operation error; or,
  • the knowledge image that has been reconstructed is deleted or replaced because it exceeds its life cycle, but it needs to be referenced due to operations such as looking back or jumping.
  • the short-term reference image is the main stream image that has been encoded before the i-th main stream image and is close to the i-th main stream image in time and can be used as the candidate reference image by the i-th main stream image (for example, 0 Reconstructed image of the decoded main stream image between ⁇ i-1).
  • the short-term reference image of the current encoded image constitutes the reference image set.
  • the decoding time of a decoded image that references at least one new knowledge image (n greater than 0) before the decoding order and is closest to the current decoded image (decoding time ti) can be expressed as tj, where
  • the new knowledge image is a knowledge image different from the knowledge image referenced by the decoded image of a reference knowledge image next next; as new knowledge images appear, tj will also be updated; more specifically, tj’s
  • a value is initialized to T, that is, T can be understood as the initial value of the decoding time of the starting image of an image sequence, which can be defined by the user as needed.
  • tj will refer to the new knowledge image It is to be understood that the replacement interval is not unique.
  • the decoder side may perform the following operations:
  • main stream image A that refers to a knowledge image
  • main stream image B that refers to a knowledge image
  • the number of images between A and B is not less than the number of images in k seconds corresponding to the frame rate f of the video sequence declared in the code stream.
  • the example k value is 1.
  • the decoder determines that the current code stream conforms to the codec standard supported by the decoder, and performs step 4;
  • the decoder determines whether the decoder can decode and play the current bitstream in real time.
  • the decoder performs the following decoding operations; when q is less than fk+ When N, the decoding is paused or terminated.
  • the decoding time tj of the main stream image referring to the new knowledge image is T, and its initialization value should ensure that the first main stream image to be decoded (the decoding time is 0 seconds) can use any knowledge
  • the image is used as a candidate reference image (for example, no more than -k seconds, so that the difference between the decoding time 0 and T of the first main stream image is not less than k seconds),
  • the knowledge images in the set L are available and decoded, but the knowledge images in the set L are not decoded or need to be decoded again.
  • the knowledge image that has been decoded is deleted or replaced because it exceeds its life cycle, but it needs to be referenced because of operations such as look back or jump.
  • the decoding time ti of any image can be obtained according to the information in the code stream, or it can be obtained by the decoder according to the actual situation, and the invention is not limited or restricted.
  • the reference picture set is composed of the short-term reference picture of the current coded picture
  • vps_library_picture_enable_flag 1-bit identifier. When the value is 1, it means that the current code stream refers to the external knowledge layer code stream; when the value is 0, it means that the current code stream does not refer to the knowledge layer code stream.
  • the number of bits in this field and the values representing different meanings can be freely defined and designed, and are not limited in the present invention.
  • min_library_interval_time 12 bits. Describe the minimum decoding time interval of the knowledge image referenced by the current bitstream, and its value range is limited by profile and level. Among them, the upper 6 bits describe the value between 0 and 59 in seconds, and the lower 6 bits describe the value between 0 and 63. When the frame rate is less than 64, the unit is the image, otherwise, the unit is 1/64 second.
  • the semantics of min_library_interval_time may be: fixed bit length or variable bit length symbols, describing the minimum decoding time interval of the knowledge image referenced by the current bitstream, for example, each bit of the syntax element describes time division Seconds, for example, the syntax element describes the number of units in seconds, and for example, the syntax element describes the number of units in images, the value range is limited by the profile and level, where different profiles and levels can determine the minimum decoding time interval The lower limit of the value range.
  • the encoder side may perform the operation as the encoder in Example 1: the decoder side may perform the operation as the decoder in Example 1.
  • sps_library_picture_enable_flag 1-bit identifier. When the value is 1, it means that the current code stream refers to the external knowledge layer code stream; when the value is 0, it means that the current code stream does not refer to the knowledge layer code stream.
  • the number of bits in this field and the values representing different meanings can be freely defined and designed, and are not limited in the present invention.
  • min_library_interval_time 12 bits. Describe the minimum decoding time interval of the knowledge image referenced by the current bitstream, and its value range is limited by profile and level. Among them, the upper 6 bits describe the value between 0 and 59 in seconds, and the lower 6 bits describe the value between 0 and 63. When the frame rate is less than 64, the unit is the image, otherwise, the unit is 1/64 second.
  • the semantics of min_library_interval_time may be: fixed bit length or variable bit length symbols, describing the minimum decoding time interval of the knowledge image referenced by the current bitstream, for example, each bit of the syntax element describes time division Seconds, for example, the syntax element describes the number of units in seconds, and for example, the syntax element describes the number of units in images, the value range is limited by the profile and level, where different profiles and levels can determine the minimum decoding time interval The lower limit of the value range.
  • the encoder side may perform the operation as the encoder in Example 1: the decoder side may perform the operation as the decoder in Example 1.
  • Scenario 1 For a main stream image A referring to the knowledge base image and another main stream image B referring to the knowledge base image, if the knowledge base images referenced by A and B are different (one or more different) ,then:
  • the number of images between A and B is not less than the number of images in k seconds corresponding to the frame rate of the video sequence declared in the code stream.
  • the example k value is 1.
  • the encoder performs the following operations:
  • L* is a knowledge image
  • R* represents an encoded image that refers to a knowledge image
  • N* represents an encoded image that does not refer to a knowledge image.
  • the encoder that generates the above example code stream performs the following example operations (for the convenience of description, the short-term reference images referenced by the R image and the N image will not be repeated):
  • N1 and N2 do not refer to knowledge images
  • N4 and N5 do not refer to knowledge images
  • N7 does not refer to knowledge images
  • N9 and N10 do not refer to knowledge images
  • the decoder performs the following operations:
  • the decoder needs to decode fk+n images in k seconds;
  • the decoder when the decoder (limited to a maximum of 1 second to resolve a knowledge image) receives a code stream as shown in Figure 6B, the decoder can complete real-time decoding:
  • the decoder when the decoder (limited to a maximum of one knowledge image per second in k seconds) receives the code stream as shown in Figure 6C, the decoder cannot complete real-time decoding of R3 and R8, because although the interval between R3 and R0 exceeds k seconds, R3 There are three more knowledge images referenced than R0; and although the knowledge image referenced by R8 is only one different from the knowledge image referenced by R6, the time interval between R8 and R6 is less than k seconds.
  • the coded image of a reference knowledge image decoded before A decoding is B, and A should meet all the following conditions:
  • the knowledge images referenced by A should have at most n knowledge images that are not referenced by B;
  • the number of images decoded between A and B is at least k seconds of images corresponding to the frame rate of the video sequence declared in the codestream number.
  • the effect of the k-second limit is that the decoding rate of n images is increased by the frame rate every k seconds.
  • the encoder performs the following operations:
  • L* is a knowledge image
  • R* represents an encoded image that refers to a knowledge image
  • N* represents an encoded image that does not refer to a knowledge image.
  • the decoder performs the following operations:
  • the decoder needs to decode fk+n images in k seconds;
  • the image between A and B does not refer to the knowledge image. If there are n different knowledge images in the knowledge images referenced by A and B, the number of images between A and B is not less than the number of k seconds corresponding to the frame rate f of the video sequence declared in the code stream, An example k value is 1.
  • the decoder when the decoder (limited to a maximum of 1 knowledge image in k seconds) receives the code stream as shown in Figure 7B, the decoder can complete real-time decoding:
  • the decoder when the decoder (limited to a maximum of one knowledge image per second in k seconds) receives the code stream as shown in Figure 7C, the decoder cannot complete real-time decoding of R3 and R8, because although the time interval between R3 and R0 exceeds k seconds, R3 There are 3 more knowledge images referenced than R0; and although the knowledge image referenced by R8 is a subset of the knowledge image referenced by R6 (which does not result in the decoding of a new knowledge image), the time interval between R8 and R6 is less than k seconds.
  • the coded image of a reference knowledge image decoded before A decoding is B, and A should meet all the following conditions:
  • the knowledge images they refer to should be the knowledge images referenced by B or a subset thereof;
  • the knowledge image referenced by A should have at most one knowledge image that is not referenced by B;
  • the number of images decoded between A and B is at least the number of images in T seconds corresponding to the frame rate of the video sequence declared in the code stream.
  • the impact of the T-second limit is that every T-second increases the decoding capacity of an image by more than the frame rate.
  • the encoder performs the following operations:
  • the initialization time T of the main stream image that refers to the knowledge image before initialization is initialized at a value not greater than -k; the set of knowledge images that can be referenced when initializing the main stream image encoding is infinite;
  • L* is a knowledge image
  • R* represents an encoded image that refers to a knowledge image
  • N* represents an encoded image that does not refer to a knowledge image.
  • the decoder performs the following operations:
  • the decoder needs to decode fk+n images within k seconds;
  • the image between A and B refers only to the knowledge image or a subset thereof referenced by A. If there are n different knowledge images in the knowledge images referenced by A and B, the number of images between A and B is not less than the number of k seconds corresponding to the frame rate f of the video sequence declared in the code stream, An example k value is 1.
  • the decoder when the decoder (limited to a maximum of one knowledge image for k seconds) receives the code stream as shown in Figure 8B, the decoder can complete real-time decoding;
  • the decoder when the decoder (limited to a maximum of one knowledge image per second in k seconds) receives the code stream as shown in Figure 8C, the decoder cannot complete real-time decoding of R3 and R8 because although the interval between R3 and R0 exceeds k seconds , But there are three more knowledge images referenced by R3 than R0; and although there is only one difference between the knowledge image referenced by R8 and the knowledge image referenced by R6, the time interval between R8 and R6 is less than k seconds.
  • the first RL image in the code stream before A and the RL image immediately after the sequence header is B.
  • A should meet all the following conditions:
  • the knowledge image referenced by A has at most one knowledge image that is not referenced by B,
  • the number of pictures decoded between A and B is at least the number of pictures in T seconds corresponding to the frame rate of the video sequence declared in the code stream.
  • the effect of the k-second limit is that each k-second increases the decoding capacity of an image by more than the frame rate.
  • the encoder performs the following operations:
  • L* is a knowledge image
  • R* represents an encoded image that refers to a knowledge image
  • RL* represents an encoded image that only refers to a knowledge image
  • N * Indicates an encoded image that does not refer to a knowledge image.
  • the decoder performs the following operations:
  • the first RL image in the code stream before A and the RL image immediately after the sequence header is B.
  • the knowledge images referenced by A are at most n knowledge images that are not referenced by B; the number of decoded images between A and B is at least k seconds of images corresponding to the frame rate f of the video sequence declared in the codestream number.
  • the effect of the k-second limit is that each k-second increases the decoding capacity of an image by more than the frame rate.
  • the decoder when the decoder (limited to a maximum of 1 second resolution knowledge image) receives the code stream as shown in Figure 9B, the decoder can complete real-time decoding;
  • the decoder when the decoder (limited to a maximum of 1 knowledge image in k seconds) receives the code stream as shown in Figure 9C, the decoder cannot complete real-time decoding of R2 and R8, because although the knowledge image referenced by RL2 and the knowledge referenced by RL0 Only one image is different, but the time interval between RL2 and RL0 is less than k seconds; although the time interval between R8 and R5 exceeds k seconds, RL8 refers to two more knowledge images than RL0.
  • this application discloses an optional decoding method 9000, which includes the following steps:
  • the first decoded image is the image closest to the sequence head immediately before the current image to be decoded in the main codestream, which supports random access and only refers to the knowledge image.
  • the first decoded image may be understood as, but not limited to, the image B in the foregoing embodiment, and the current image to be decoded may be understood as, but not limited to, the image A in the foregoing embodiment.
  • S9002 Use the new knowledge image as the reference image of the current image to be decoded; the current image to be decoded is an image that supports random access and only references the knowledge image.
  • the number of decoded images between the current image to be decoded and the first decoded image is at least f*k; for example, but not limited to f*k+n; k is one of the knowledge images allowed by the main stream
  • the minimum decoding time interval between; f is the frame rate of the video sequence declared in the main stream; the number of new knowledge images is not greater than the preset value n; n is a positive integer; the above new knowledge images are the current images to be decoded (such as The image A) does not include the knowledge image referenced by the first decoded image (such as image B) in the knowledge image referenced; the new knowledge image is obtained by decoding the knowledge base code stream.
  • the value of n may include but is not limited to 1, 2; the new knowledge image may be obtained by decoding the knowledge base code stream.
  • the above method 900 may further include:
  • the above method 9000 may be executed or applied on the device 1000 (see FIG. 12).
  • the second obtaining module 1002 can execute the foregoing S9001; the determining module 1003 can execute the foregoing S9002.
  • the device 1000 may further include a decoding module 1004 (not shown in FIG. 12), and specifically may execute the foregoing S9003.
  • the RL images that are later in the bitstream can only refer to one that is different from the earlier ones in the bitstream.
  • the knowledge image referenced by the RL image when the later RL image in the bitstream refers to a knowledge image different from that referenced by the earlier RL image in the bitstream, at least T seconds of display should be included between the two consecutive sequence headers image.
  • the impact of the T-second limit is that every T-second increases the decoding capacity of an image by more than the frame rate.
  • the encoder performs the following operations:
  • FIG. 10A An example of the structure of the code stream generated by the above-mentioned encoder is shown in FIG. 10A, where there is no above-mentioned decoding restriction between RL3 and RL0.
  • L* is a knowledge image
  • R* represents an encoded image that refers to a knowledge image
  • RL* represents an encoded image that only refers to a knowledge image
  • N* represents an encoded image that does not refer to a knowledge image.
  • the decoder performs the following operations:
  • the decoder needs to decode fk+n images in k seconds;
  • the first RL image in the code stream before A and the RL image immediately after the sequence header is B .
  • the knowledge images referenced by A are at most n knowledge images that are not referenced by B; the number of decoded images between A and B is at least k seconds of images corresponding to the frame rate f of the video sequence declared in the codestream number.
  • the effect of the k-second limit is that each k-second increases the decoding capacity of an image by more than the frame rate.
  • the decoder when the decoder (limited to a maximum of 1 knowledge image in k seconds) receives the code stream as shown in Figure 10B, the decoder can complete real-time decoding, because although RL0 refers to multiple knowledge images, due to the delay in startup Allowed, the decoding time of the RL0 knowledge image can be obtained by increasing the startup delay, so although the RL3 reference knowledge image is 2 more than the RL0 knowledge image, the RL3 knowledge image decoding time is not affected between RL0 and RL3 Time interval constraints;
  • the decoder when the decoder (limited to a maximum of one knowledge image per second in k seconds) receives the code stream as shown in Figure 10C, the decoder cannot complete real-time decoding of RL6 and RL8, because although the time interval between RL6 and RL3 exceeds k seconds, However, there are two knowledge images referenced by RL6 that are different from RL3; although only one knowledge image referenced by RL8 is different from the knowledge image referenced by RL6, the time interval between RL8 and RL6 is less than k seconds:
  • an embodiment of the present invention further provides a device 1000, which includes a first acquisition module 1001, a second acquisition module 1002, and a determination module 1003, where:
  • the first obtaining module 1001 is configured to obtain a first identifier from a code stream, and the first identifier is used to indicate a minimum decoding time interval k between knowledge images allowed by the code stream;
  • the second obtaining module 1002 is used for decoding if the current decoded image refers to the knowledge image
  • the determining module 1003 is configured to determine a preset number of knowledge images as candidate reference images of the current decoded image according to the relationship between the difference between ti and tj and the magnitude of k.
  • first acquisition module 1001, second acquisition module 1002, and determination module 1003 can be applied to the inter prediction process on the encoding side or the decoding side. Specifically, on the encoding side, these modules can be applied to the inter prediction unit 244 in the prediction processing unit 260 of the aforementioned encoder 20; on the decoding side, these modules can be applied to the frames in the prediction processing unit 360 of the aforementioned decoder 30. Inter-prediction unit 344.
  • Computer readable media may include computer readable storage media, which corresponds to tangible media, such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another (eg, according to a communication protocol).
  • computer-readable media may generally correspond to (1) non-transitory tangible computer-readable storage media, or (2) communication media, such as signals or carrier waves.
  • Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementation of the techniques described in this application.
  • the computer program product may include a computer-readable medium.
  • Such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory, or may be used to store instructions or data structures
  • the desired program code in the form of and any other medium that can be accessed by the computer. And, any connection is properly called a computer-readable medium.
  • coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared, radio, and microwave are used to transmit instructions from a website, server, or other remote source
  • coaxial cable Wire, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media.
  • the computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other temporary media, but are actually directed to non-transitory tangible storage media.
  • magnetic disks and optical discs include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), and Blu-ray discs, where magnetic discs usually reproduce data magnetically, while optical discs reproduce optically using lasers data. Combinations of the above should also be included within the scope of computer-readable media.
  • DSPs digital signal processors
  • ASICs application specific integrated circuits
  • FPGAs field programmable logic arrays
  • processors may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein.
  • the functions described in the various illustrative logical blocks, modules, and steps described herein may be provided within dedicated hardware and/or software modules configured for encoding and decoding, or in combination Into the combined codec.
  • the techniques can be fully implemented in one or more circuits or logic elements.
  • the technology of the present application may be implemented in a variety of devices or equipment, including wireless handsets, integrated circuits (ICs), or a set of ICs (eg, chipsets).
  • ICs integrated circuits
  • a set of ICs eg, chipsets
  • Various components, modules or units are described in this application to emphasize the functional aspects of the device for performing the disclosed technology, but do not necessarily need to be implemented by different hardware units.
  • various units may be combined in a codec hardware unit in combination with suitable software and/or firmware, or by interoperating hardware units (including one or more processors as described above) provide.

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Abstract

本申请公开了一种缓解解码峰值的解码方法以及设备，该方法包括：从码流中获取第一标识，所述第一标识用于表示所述码流允许的知识图像之间的最小解码时间间隔k；若当前解码图像参考了知识图像进行解码，解析码流时获取当前解码图像的解码时刻ti与最近一次参考了新的知识图像的第一解码图像的解码时刻tj，其中，所述新的知识图像为解码所述第一解码图像时未被解码或需要重新解码的知识图像；根据ti与tj的差值与k的大小关系，确定出预设数量个知识图像作为所述当前解码图像的候选参考图像。实施本申请能够提高编解码中的预测准确性，提升编码效率。

Description

视频编码器、视频解码器及相应方法 技术领域
本发明涉及视频编解码领域，尤其涉及一种视频图像的编码和解码方法、装置以及相应的编码器和解码器。
背景技术
数字视频能力可并入到多种多样的装置中，包含数字电视、数字直播系统、无线广播系统、个人数字助理(PDA)、膝上型或桌上型计算机、平板计算机、电子图书阅读器、数码相机、数字记录装置、数字媒体播放器、视频游戏装置、视频游戏控制台、蜂窝式或卫星无线电电话(所谓的“智能电话”)、视频电话会议装置、视频流式传输装置及其类似者。数字视频装置实施视频压缩技术，例如，在由MPEG-2、MPEG-4、ITU-T H.263、ITU-T H.264/MPEG-4第10部分高级视频编码(AVC)定义的标准、视频编码标准H.265/高效视频编码(HEVC)标准以及此类标准的扩展中所描述的视频压缩技术。视频装置可通过实施此类视频压缩技术来更有效率地发射、接收、编码、解码和/或存储数字视频信息。
视频压缩技术执行空间(图像内)预测和/或时间(图像间)预测以减少或去除视频序列中固有的冗余。对于基于块的视频编码，视频条带(即，视频帧或视频帧的一部分)可分割成若干图像块，所述图像块也可被称作树块、编码单元(CU)和/或编码节点。使用关于同一图像中的相邻块中的参考样本的空间预测来编码图像的待帧内编码(I)条带中的图像块。图像的待帧间编码(P或B)条带中的图像块可使用相对于同一图像中的相邻块中的参考样本的空间预测或相对于其它参考图像中的参考样本的时间预测。图像可被称作帧，且参考图像可被称作参考帧。
发明内容
本申请实施例提供一种视频图像的编解码方法、装置及相应的编码器和解码器，一定程度上提高图像块的运动信息的预测准确性，从而提高编解码性能。
第一方面，本申请实施例提供了一种视频解码方法，包括：
从码流中获取第一标识，所述第一标识用于表示所述码流允许的知识图像之间的最小解码时间间隔k；
若当前解码图像参考了知识图像进行解码，
解析码流时获取当前解码图像的解码时刻t i与最近一次参考了新的知识图像的第一解码图像的解码时刻t j，其中，所述新的知识图像为解码所述第一解码图像时未被解码或需要重新解码的知识图像；
根据t i与t j的差值与k的大小关系，确定出预设数量个知识图像作为所述当前解 码图像的候选参考图像。
第二方面，本申请实施例提供一种解码装置，包括用于实施第一方面的任意一种方法的若干个功能单元。举例来说，该解码装置可以包括：
第一获取模块，用于从码流中获取第一标识，所述第一标识用于表示所述码流允许的知识图像之间的最小解码时间间隔k；
第二获取模块，用于若当前解码图像参考了知识图像进行解码，
解析码流时获取当前解码图像的解码时刻t i与最近一次参考了新的知识图像的第一解码图像的解码时刻t j，其中，所述新的知识图像为解码所述第一解码图像时未被解码或需要重新解码的知识图像；
确定模块，用于根据t i与t j的差值与k的大小关系，确定出预设数量个知识图像作为所述当前解码图像的候选参考图像。
基于第一方面或第二方面，在一些可能的实施方式下，所述k不小于所述码流符合的profile或level允许的最小解码时间间下限。
基于第一方面或第二方面，在一些可能的实施方式下，所述根据t i与t j的差值与k的大小关系，确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
若t i-t j不小于k，则确定出n个知识图像作为所述当前解码图像的候选参考图像；所述n个知识图像包括当前未解码或需要进行重新解码的知识图像，n为正整数。
基于第一方面或第二方面，在一些可能的实施方式下，若t i-t j不小于k，则确定出m+n个知识图像作为所述当前解码图像的候选参考图像；其中，m个知识图像包括已解码的知识图像，n个知识图像包括当前未解码或需要进行重新解码的知识图像，m，n为正整数。
基于第一方面或第二方面，在一些可能的实施方式下，所述确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
在当前未解码或需要重新解码的知识图像中确定出与所述当前解码图像内容相似性最高的n个知识图像。
基于第一方面或第二方面，在一些可能的实施方式下，所述确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
在当前未解码或需要进行重新解码的知识图像中确定出与所述当前解码图像显示时刻最接近n个的知识图像。
基于第一方面或第二方面，在一些可能的实施方式下，所述确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
在当前未解码或需要重新解码的知识图像中确定出n个编码效率最高的知识图像。
基于第一方面或第二方面，在一些可能的实施方式下，所述根据t i与t j的差值与k的大小关系，确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
若t i-t j小于k，则确定出m个知识图像作为所述当前解码图像的候选参考图像； 其中，m个知识图像包括已解码且不需要重新编码的知识图像，m为正整数。
第三方面，本申请实施例提供了一种视频解码方法，包括：
获取第一解码图像；所述第一解码图像为主码流中在当前待解码图像之前最近一个紧随序列头后的支持随机访问且仅参考知识图像的图像；
将新知识图像作为所述当前待解码图像的参考图像；所述当前待解码图像为支持随机访问且仅参考知识图像的图像；
其中，在所述主码流中，所述当前待解码图像和所述第一解码图像之间解码的图像的数目至少为f*k；所述k为所述主码流允许的知识图像之间的最小解码时间间隔；所述f为所述主码流中声明的视频序列的帧率；所述新知识图像的个数不大于预设值n；所述n为正整数；所述新知识图像为所述当前待解码图像参考的知识图像中没有被所述第一解码图像所参考的知识图像。
第四方面，本申请实施例提供了一种视频解码装置，该装置包括：
第二获取模块，用于获取第一解码图像；所述第一解码图像为主码流中在当前待解码图像之前最近一个紧随序列头后的支持随机访问且仅参考知识图像的图像；
确定模块，用于将新知识图像作为所述当前待解码图像的参考图像；所述当前待解码图像为支持随机访问且仅参考知识图像的图像；
其中，在所述主码流中，所述当前待解码图像和所述第一解码图像之间解码的图像的数目至少为f*k；所述k为所述主码流允许的知识图像之间的最小解码时间间隔；所述f为所述主码流中声明的视频序列的帧率；所述新知识图像的个数不大于预设值n；所述n为正整数；所述新知识图像为所述当前待解码图像参考的知识图像中没有被所述第一解码图像所参考的知识图像。
基于第三方面或第四方面，在一些可能的实施方式下，方法还包括：根据所述新知识图像解码所述当前待解码图像。相应地，上述装置还包括解码模块，用于执行该步骤。
基于第三方面或第四方面，在一些可能的实施方式下，n＝1。
基于第三方面或第四方面，在一些可能的实施方式下，所述新知识图像是通过解码知识库码流得到的。
第五方面，本申请实施例提供一种用于解码视频数据的设备，所述设备包括：
存储器，用于存储码流形式的视频数据；
视频解码器，用于执行第一方面或第三方面中的任意可能的实现方法。
第六方面，本申请实施例提供一种用于编码视频数据的设备，所述设备包括：
存储器，用于存储视频数据，所述视频数据包括一个或多个图像块；
视频编码器，用于执行与第一方面或第三方面中的任意可能的相耦合的实现方法。
第七方面，本申请实施例提供一种编码设备，包括：相互耦合的非易失性存储器 和处理器，所述处理器调用存储在所述存储器中的程序代码以执行与第一方面的任意一种方法相耦合的部分或全部步骤。
第八方面，本申请实施例提供一种解码设备，包括：相互耦合的非易失性存储器和处理器，所述处理器调用存储在所述存储器中的程序代码以执行第一方面的任意一种方法的部分或全部步骤。
第九方面，本申请实施例提供一种计算机可读存储介质，所述计算机可读存储介质存储了程序代码，其中，所述程序代码包括用于执行第一方面的任意一种方法的部分或全部步骤的指令。
第十方面，本申请实施例提供一种计算机程序产品，当所述计算机程序产品在计算机上运行时，使得所述计算机执行第一方面的任意一种方法的部分或全部步骤。
应当理解的是，本申请的任意方面的可能的实现方式在不违背自然规律的条件下可以自由组合，一些对应的可行实施方式实现方法类似，所取得的有益效果相似，不再赘述。
可以看到，本发明实施例可以缓解解码峰值。
附图说明
为了更清楚地说明本发明实施例或背景技术中的技术方案，下面将对本发明实施例或背景技术中所需要使用的附图进行说明。
图1A是用于实现本发明实施例的视频编码及解码系统10实例的框图；
图1B是用于实现本发明实施例的视频译码系统40实例的框图；
图2是用于实现本发明实施例的编码器20实例结构的框图；
图3是用于实现本发明实施例的解码器30实例结构的框图；
图4是用于实现本发明实施例的视频译码设备400实例的框图；
图5是用于实现本发明实施例的另一种编码装置或解码装置实例的框图；
图6A是本发明实施例中一种可能的结构码流示例；
图6B是本发明实施例中一种可能的结构码流示例；
图6C是本发明实施例中一种可能的结构码流示例；
图7A是本发明实施例中一种可能的结构码流示例；
图7B是本发明实施例中一种可能的结构码流示例；
图7C是本发明实施例中一种可能的结构码流示例；
图8A是本发明实施例中一种可能的结构码流示例；
图8B是本发明实施例中一种可能的结构码流示例；
图8C是本发明实施例中一种可能的结构码流示例；
图9A是本发明实施例中一种可能的结构码流示例；
图9B是本发明实施例中一种可能的结构码流示例；
图9C是本发明实施例中一种可能的结构码流示例；
图9D是本发明实施例中一种解码方法的流程示意图；
图10A是本发明实施例中一种可能的结构码流示例；
图10B是本发明实施例中一种可能的结构码流示例；
图10C是本发明实施例中一种可能的结构码流示例；
图11是用于实现本发明实施例的一种解码方法的流程示意图；
图12是用于实现本发明实施例的一种设备的结构框图。
具体实施方式
下面结合本发明实施例中的附图对本发明实施例进行描述。以下描述中，参考形成本公开一部分并以说明之方式示出本发明实施例的具体方面或可使用本发明实施例的具体方面的附图。应理解，本发明实施例可在其它方面中使用，并可包括附图中未描绘的结构或逻辑变化。因此，以下详细描述不应以限制性的意义来理解，且本发明的范围由所附权利要求书界定。例如，应理解，结合所描述方法的揭示内容可以同样适用于用于执行所述方法的对应设备或系统，且反之亦然。例如，如果描述一个或多个具体方法步骤，则对应的设备可以包含如功能单元等一个或多个单元，来执行所描述的一个或多个方法步骤(例如，一个单元执行一个或多个步骤，或多个单元，其中每个都执行多个步骤中的一个或多个)，即使附图中未明确描述或说明这种一个或多个单元。另一方面，例如，如果基于如功能单元等一个或多个单元描述具体装置，则对应的方法可以包含一个步骤来执行一个或多个单元的功能性(例如，一个步骤执行一个或多个单元的功能性，或多个步骤，其中每个执行多个单元中一个或多个单元的功能性)，即使附图中未明确描述或说明这种一个或多个步骤。进一步，应理解的是，除非另外明确提出，本文中所描述的各示例性实施例和/或方面的特征可以相互组合。
本发明实施例所涉及的技术方案不仅可能应用于现有的视频编码标准中(如H.264、HEVC等标准)，还可能应用于未来的视频编码标准中(如H.266标准)。本发明的实施方式部分使用的术语仅用于对本发明的具体实施例进行解释，而非旨在限定本发明。下面先对本发明实施例可能涉及的一些概念进行简单介绍。
视频编码通常是指处理形成视频或视频序列的图片序列。在视频编码领域，术语“图片(picture)”、“帧(frame)”或“图像(image)”可以用作同义词。本文中使用的视频编码表示视频编码或视频解码。视频编码在源侧执行，通常包括处理(例如，通过压缩)原始视频图片以减少表示该视频图片所需的数据量，从而更高效地存储和/或传输。视频解码在目的地侧执行，通常包括相对于编码器作逆处理，以重构视频图片。实施例涉及的视频图片“编码”应理解为涉及视频序列的“编码”或“解码”。编码部分和解码部分的组合也称为编解码(编码和解码)。
视频序列包括一系列图像(picture)，图像被进一步划分为切片(slice)，切片再被划分为块(block)。视频编码以块为单位进行编码处理，在一些新的视频编码标准中，块的概念被进一步扩展。比如，在H.264标准中有宏块(macroblock，MB)，宏块可进一步划分成多个可用于预测编码的预测块(partition)。在高性能视频编码(high efficiency video coding，HEVC)标准中，采用编码单元(coding unit，CU)，预测单元(prediction unit，PU)和变换单元(transform unit，TU)等基本概念，从功能上划分了多种块单元， 并采用全新的基于树结构进行描述。比如CU可以按照四叉树进行划分为更小的CU，而更小的CU还可以继续划分，从而形成一种四叉树结构，CU是对编码图像进行划分和编码的基本单元。对于PU和TU也有类似的树结构，PU可以对应预测块，是预测编码的基本单元。对CU按照划分模式进一步划分成多个PU。TU可以对应变换块，是对预测残差进行变换的基本单元。然而，无论CU，PU还是TU，本质上都属于块(或称图像块)的概念。
例如在HEVC中，通过使用表示为编码树的四叉树结构将CTU拆分为多个CU。在CU层级处作出是否使用图片间(时间)或图片内(空间)预测对图片区域进行编码的决策。每个CU可以根据PU拆分类型进一步拆分为一个、两个或四个PU。一个PU内应用相同的预测过程，并在PU基础上将相关信息传输到解码器。在通过基于PU拆分类型应用预测过程获取残差块之后，可以根据类似于用于CU的编码树的其它四叉树结构将CU分割成变换单元(transform unit，TU)。在视频压缩技术最新的发展中，使用四叉树和二叉树(Quad-tree and binary tree，QTBT)分割帧来分割编码块。在QTBT块结构中，CU可以为正方形或矩形形状。
本文中，为了便于描述和理解，可将当前编码图像中待编码的图像块称为当前块，例如在编码中，指当前正在编码的块；在解码中，指当前正在解码的块。将参考图像中用于对当前块进行预测的已解码的图像块称为参考块，即参考块是为当前块提供参考信号的块，其中，参考信号表示图像块内的像素值。可将参考图像中为当前块提供预测信号的块为预测块，其中，预测信号表示预测块内的像素值或者采样值或者采样信号。例如，在遍历多个参考块以后，找到了最佳参考块，此最佳参考块将为当前块提供预测，此块称为预测块。
无损视频编码情况下，可以重构原始视频图片，即经重构视频图片具有与原始视频图片相同的质量(假设存储或传输期间没有传输损耗或其它数据丢失)。在有损视频编码情况下，通过例如量化执行进一步压缩，来减少表示视频图片所需的数据量，而解码器侧无法完全重构视频图片，即经重构视频图片的质量相比原始视频图片的质量较低或较差。
H.261的几个视频编码标准属于“有损混合型视频编解码”(即，将样本域中的空间和时间预测与变换域中用于应用量化的2D变换编码结合)。视频序列的每个图片通常分割成不重叠的块集合，通常在块层级上进行编码。换句话说，编码器侧通常在块(视频块)层级处理亦即编码视频，例如，通过空间(图片内)预测和时间(图片间)预测来产生预测块，从当前块(当前处理或待处理的块)减去预测块以获取残差块，在变换域变换残差块并量化残差块，以减少待传输(压缩)的数据量，而解码器侧将相对于编码器的逆处理部分应用于经编码或经压缩块，以重构用于表示的当前块。另外，编码器复制解码器处理循环，使得编码器和解码器生成相同的预测(例如帧内预测和帧间预测)和/或重构，用于处理亦即编码后续块。
下面描述本发明实施例所应用的系统架构。参见图1A，图1A示例性地给出了本发明实施例所应用的视频编码及解码系统10的示意性框图。如图1A所示，视频编码及解码系统10可包括源设备12和目的地设备14，源设备12产生经编码视频数据， 因此，源设备12可被称为视频编码装置。目的地设备14可对由源设备12所产生的经编码的视频数据进行解码，因此，目的地设备14可被称为视频解码装置。源设备12、目的地设备14或两个的各种实施方案可包含一或多个处理器以及耦合到所述一或多个处理器的存储器。所述存储器可包含但不限于RAM、ROM、EEPROM、快闪存储器或可用于以可由计算机存取的指令或数据结构的形式存储所要的程序代码的任何其它媒体，如本文所描述。源设备12和目的地设备14可以包括各种装置，包含桌上型计算机、移动计算装置、笔记型(例如，膝上型)计算机、平板计算机、机顶盒、例如所谓的“智能”电话等电话手持机、电视机、相机、显示装置、数字媒体播放器、视频游戏控制台、车载计算机、无线通信设备或其类似者。
虽然图1A将源设备12和目的地设备14绘示为单独的设备，但设备实施例也可以同时包括源设备12和目的地设备14或同时包括两者的功能性，即源设备12或对应的功能性以及目的地设备14或对应的功能性。在此类实施例中，可以使用相同硬件和/或软件，或使用单独的硬件和/或软件，或其任何组合来实施源设备12或对应的功能性以及目的地设备14或对应的功能性。
源设备12和目的地设备14之间可通过链路13进行通信连接，目的地设备14可经由链路13从源设备12接收经编码视频数据。链路13可包括能够将经编码视频数据从源设备12移动到目的地设备14的一或多个媒体或装置。在一个实例中，链路13可包括使得源设备12能够实时将经编码视频数据直接发射到目的地设备14的一或多个通信媒体。在此实例中，源设备12可根据通信标准(例如无线通信协议)来调制经编码视频数据，且可将经调制的视频数据发射到目的地设备14。所述一或多个通信媒体可包含无线和/或有线通信媒体，例如射频(RF)频谱或一或多个物理传输线。所述一或多个通信媒体可形成基于分组的网络的一部分，基于分组的网络例如为局域网、广域网或全球网络(例如，因特网)。所述一或多个通信媒体可包含路由器、交换器、基站或促进从源设备12到目的地设备14的通信的其它设备。
源设备12包括编码器20，另外可选地，源设备12还可以包括图片源16、图片预处理器18、以及通信接口22。具体实现形态中，所述编码器20、图片源16、图片预处理器18、以及通信接口22可能是源设备12中的硬件部件，也可能是源设备12中的软件程序。分别描述如下：
图片源16，可以包括或可以为任何类别的图片捕获设备，用于例如捕获现实世界图片，和/或任何类别的图片或评论(对于屏幕内容编码，屏幕上的一些文字也认为是待编码的图片或图像的一部分)生成设备，例如，用于生成计算机动画图片的计算机图形处理器，或用于获取和/或提供现实世界图片、计算机动画图片(例如，屏幕内容、虚拟现实(virtual reality，VR)图片)的任何类别设备，和/或其任何组合(例如，实景(augmented reality，AR)图片)。图片源16可以为用于捕获图片的相机或者用于存储图片的存储器，图片源16还可以包括存储先前捕获或产生的图片和/或获取或接收图片的任何类别的(内部或外部)接口。当图片源16为相机时，图片源16可例如为本地的或集成在源设备中的集成相机；当图片源16为存储器时，图片源16可为本地的或例如集成在源设备中的集成存储器。当所述图片源16包括接口时，接口可例如为从外部视频源接收图片的外部接口，外部视频源例如为外部图片捕获设备，比如相 机、外部存储器或外部图片生成设备，外部图片生成设备例如为外部计算机图形处理器、计算机或服务器。接口可以为根据任何专有或标准化接口协议的任何类别的接口，例如有线或无线接口、光接口。
其中，图片可以视为像素点(picture element)的二维阵列或矩阵。阵列中的像素点也可以称为采样点。阵列或图片在水平和垂直方向(或轴线)上的采样点数目定义图片的尺寸和/或分辨率。为了表示颜色，通常采用三个颜色分量，即图片可以表示为或包含三个采样阵列。例如在RBG格式或颜色空间中，图片包括对应的红色、绿色及蓝色采样阵列。但是，在视频编码中，每个像素通常以亮度/色度格式或颜色空间表示，例如对于YUV格式的图片，包括Y指示的亮度分量(有时也可以用L指示)以及U和V指示的两个色度分量。亮度(luma)分量Y表示亮度或灰度水平强度(例如，在灰度等级图片中两者相同)，而两个色度(chroma)分量U和V表示色度或颜色信息分量。相应地，YUV格式的图片包括亮度采样值(Y)的亮度采样阵列，和色度值(U和V)的两个色度采样阵列。RGB格式的图片可以转换或变换为YUV格式，反之亦然，该过程也称为色彩变换或转换。如果图片是黑白的，该图片可以只包括亮度采样阵列。本发明实施例中，由图片源16传输至图片处理器的图片也可称为原始图片数据17。
图片预处理器18，用于接收原始图片数据17并对原始图片数据17执行预处理，以获取经预处理的图片19或经预处理的图片数据19。例如，图片预处理器18执行的预处理可以包括整修、色彩格式转换(例如，从RGB格式转换为YUV格式)、调色或去噪。
编码器20(或称视频编码器20)，用于接收经预处理的图片数据19，采用相关预测模式(如本文各个实施例中的预测模式)对经预处理的图片数据19进行处理，从而提供经编码图片数据21(下文将进一步基于图2或图4或图5描述编码器20的结构细节)。在一些实施例中，编码器20可以用于执行后文所描述的各个实施例，以实现本发明所描述的色度块预测方法在编码侧的应用。
通信接口22，可用于接收经编码图片数据21，并可通过链路13将经编码图片数据21传输至目的地设备14或任何其它设备(如存储器)，以用于存储或直接重构，所述其它设备可为任何用于解码或存储的设备。通信接口22可例如用于将经编码图片数据21封装成合适的格式，例如数据包，以在链路13上传输。
目的地设备14包括解码器30，另外可选地，目的地设备14还可以包括通信接口28、图片后处理器32和显示设备34。分别描述如下：
通信接口28，可用于从源设备12或任何其它源接收经编码图片数据21，所述任何其它源例如为存储设备，存储设备例如为经编码图片数据存储设备。通信接口28可以用于藉由源设备12和目的地设备14之间的链路13或藉由任何类别的网络传输或接收经编码图片数据21，链路13例如为直接有线或无线连接，任何类别的网络例如为有线或无线网络或其任何组合，或任何类别的私网和公网，或其任何组合。通信接口28可以例如用于解封装通信接口22所传输的数据包以获取经编码图片数据21。
通信接口28和通信接口22都可以配置为单向通信接口或者双向通信接口，以及可以用于例如发送和接收消息来建立连接、确认和交换任何其它与通信链路和/或例如 经编码图片数据传输的数据传输有关的信息。
解码器30(或称为解码器30)，用于接收经编码图片数据21并提供经解码图片数据31或经解码图片31(下文将进一步基于图3或图4或图5描述解码器30的结构细节)。在一些实施例中，解码器30可以用于执行后文所描述的各个实施例，以实现本发明所描述的色度块预测方法在解码侧的应用。
图片后处理器32，用于对经解码图片数据31(也称为经重构图片数据)执行后处理，以获得经后处理图片数据33。图片后处理器32执行的后处理可以包括：色彩格式转换(例如，从YUV格式转换为RGB格式)、调色、整修或重采样，或任何其它处理，还可用于将将经后处理图片数据33传输至显示设备34。
显示设备34，用于接收经后处理图片数据33以向例如用户或观看者显示图片。显示设备34可以为或可以包括任何类别的用于呈现经重构图片的显示器，例如，集成的或外部的显示器或监视器。例如，显示器可以包括液晶显示器(liquid crystal display，LCD)、有机发光二极管(organic light emitting diode，OLED)显示器、等离子显示器、投影仪、微LED显示器、硅基液晶(liquid crystal on silicon，LCoS)、数字光处理器(digital light processor，DLP)或任何类别的其它显示器。
虽然，图1A将源设备12和目的地设备14绘示为单独的设备，但设备实施例也可以同时包括源设备12和目的地设备14或同时包括两者的功能性，即源设备12或对应的功能性以及目的地设备14或对应的功能性。在此类实施例中，可以使用相同硬件和/或软件，或使用单独的硬件和/或软件，或其任何组合来实施源设备12或对应的功能性以及目的地设备14或对应的功能性。
本领域技术人员基于描述明显可知，不同单元的功能性或图1A所示的源设备12和/或目的地设备14的功能性的存在和(准确)划分可能根据实际设备和应用有所不同。源设备12和目的地设备14可以包括各种设备中的任一个，包含任何类别的手持或静止设备，例如，笔记本或膝上型计算机、移动电话、智能手机、平板或平板计算机、摄像机、台式计算机、机顶盒、电视机、相机、车载设备、显示设备、数字媒体播放器、视频游戏控制台、视频流式传输设备(例如内容服务服务器或内容分发服务器)、广播接收器设备、广播发射器设备等，并可以不使用或使用任何类别的操作系统。
编码器20和解码器30都可以实施为各种合适电路中的任一个，例如，一个或多个微处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application-specific integrated circuit，ASIC)、现场可编程门阵列(field-programmable gate array，FPGA)、离散逻辑、硬件或其任何组合。如果部分地以软件实施所述技术，则设备可将软件的指令存储于合适的非暂时性计算机可读存储介质中，且可使用一或多个处理器以硬件执行指令从而执行本公开的技术。前述内容(包含硬件、软件、硬件与软件的组合等)中的任一者可视为一或多个处理器。
在一些情况下，图1A中所示视频编码及解码系统10仅为示例，本申请的技术可以适用于不必包含编码和解码设备之间的任何数据通信的视频编码设置(例如，视频编码或视频解码)。在其它实例中，数据可从本地存储器检索、在网络上流式传输等。视频编码设备可以对数据进行编码并且将数据存储到存储器，和/或视频解码设备可以 从存储器检索数据并且对数据进行解码。在一些实例中，由并不彼此通信而是仅编码数据到存储器和/或从存储器检索数据且解码数据的设备执行编码和解码。
参见图1B，图1B是根据一示例性实施例的包含图2的编码器20和/或图3的解码器30的视频译码系统40的实例的说明图。视频译码系统40可以实现本发明实施例的各种技术的组合。在所说明的实施方式中，视频译码系统40可以包含成像设备41、编码器20、解码器30(和/或藉由处理单元46的逻辑电路47实施的视频编/解码器)、天线42、一个或多个处理器43、一个或多个存储器44和/或显示设备45。
如图1B所示，成像设备41、天线42、处理单元46、逻辑电路47、编码器20、解码器30、处理器43、存储器44和/或显示设备45能够互相通信。如所论述，虽然用编码器20和解码器30绘示视频译码系统40，但在不同实例中，视频译码系统40可以只包含编码器20或只包含解码器30。
在一些实例中，天线42可以用于传输或接收视频数据的经编码比特流。另外，在一些实例中，显示设备45可以用于呈现视频数据。在一些实例中，逻辑电路47可以通过处理单元46实施。处理单元46可以包含专用集成电路(application-specific integrated circuit，ASIC)逻辑、图形处理器、通用处理器等。视频译码系统40也可以包含可选的处理器43，该可选处理器43类似地可以包含专用集成电路(application-specific integrated circuit，ASIC)逻辑、图形处理器、通用处理器等。在一些实例中，逻辑电路47可以通过硬件实施，如视频编码专用硬件等，处理器43可以通过通用软件、操作系统等实施。另外，存储器44可以是任何类型的存储器，例如易失性存储器(例如，静态随机存取存储器(Static Random Access Memory，SRAM)、动态随机存储器(Dynamic Random Access Memory，DRAM)等)或非易失性存储器(例如，闪存等)等。在非限制性实例中，存储器44可以由超速缓存内存实施。在一些实例中，逻辑电路47可以访问存储器44(例如用于实施图像缓冲器)。在其它实例中，逻辑电路47和/或处理单元46可以包含存储器(例如，缓存等)用于实施图像缓冲器等。
在一些实例中，通过逻辑电路实施的编码器20可以包含(例如，通过处理单元46或存储器44实施的)图像缓冲器和(例如，通过处理单元46实施的)图形处理单元。图形处理单元可以通信耦合至图像缓冲器。图形处理单元可以包含通过逻辑电路47实施的编码器20，以实施参照图2和/或本文中所描述的任何其它编码器系统或子系统所论述的各种模块。逻辑电路可以用于执行本文所论述的各种操作。
在一些实例中，解码器30可以以类似方式通过逻辑电路47实施，以实施参照图3的解码器30和/或本文中所描述的任何其它解码器系统或子系统所论述的各种模块。在一些实例中，逻辑电路实施的解码器30可以包含(通过处理单元2820或存储器44实施的)图像缓冲器和(例如，通过处理单元46实施的)图形处理单元。图形处理单元可以通信耦合至图像缓冲器。图形处理单元可以包含通过逻辑电路47实施的解码器30，以实施参照图3和/或本文中所描述的任何其它解码器系统或子系统所论述的各种模块。
在一些实例中，天线42可以用于接收视频数据的经编码比特流。如所论述，经编 码比特流可以包含本文所论述的与编码视频帧相关的数据、指示符、索引值、模式选择数据等，例如与编码分割相关的数据(例如，变换系数或经量化变换系数，(如所论述的)可选指示符，和/或定义编码分割的数据)。视频译码系统40还可包含耦合至天线42并用于解码经编码比特流的解码器30。显示设备45用于呈现视频帧。
应理解，本发明实施例中对于参考编码器20所描述的实例，解码器30可以用于执行相反过程。关于信令语法元素，解码器30可以用于接收并解析这种语法元素，相应地解码相关视频数据。在一些例子中，编码器20可以将语法元素熵编码成经编码视频比特流。在此类实例中，解码器30可以解析这种语法元素，并相应地解码相关视频数据。
需要说明的是，本发明实施例描述的编解码方法主要用于帧间预测过程，此过程在编码器20和解码器30均存在，本发明实施例中的编码器20和解码器30可以是例如H.263、H.264、HEVV、MPEG-2、MPEG-4、VP8、VP9等视频标准协议或者下一代视频标准协议(如H.266等)对应的编/解码器。
参见图2，图2示出用于实现本发明实施例的编码器20的实例的示意性/概念性框图。在图2的实例中，编码器20包括残差计算单元204、变换处理单元206、量化单元208、逆量化单元210、逆变换处理单元212、重构单元214、缓冲器216、环路滤波器单元220、经解码图片缓冲器(decoded picture buffer，DPB)230、预测处理单元260和熵编码单元270。预测处理单元260可以包含帧间预测单元244、帧内预测单元254和模式选择单元262。帧间预测单元244可以包含运动估计单元和运动补偿单元(未图示)。图2所示的编码器20也可以称为混合型视频编码器或根据混合型视频编解码器的视频编码器。
例如，残差计算单元204、变换处理单元206、量化单元208、预测处理单元260和熵编码单元270形成编码器20的前向信号路径，而例如逆量化单元210、逆变换处理单元212、重构单元214、缓冲器216、环路滤波器220、经解码图片缓冲器(decoded picture buffer，DPB)230、预测处理单元260形成编码器的后向信号路径，其中编码器的后向信号路径对应于解码器的信号路径(参见图3中的解码器30)。
编码器20通过例如输入202，接收图片201或图片201的图像块203，例如，形成视频或视频序列的图片序列中的图片。图像块203也可以称为当前图片块或待编码图片块，图片201可以称为当前图片或待编码图片(尤其是在视频编码中将当前图片与其它图片区分开时，其它图片例如同一视频序列亦即也包括当前图片的视频序列中的先前经编码和/或经解码图片)。
编码器20的实施例可以包括分割单元(图2中未绘示)，用于将图片201分割成多个例如图像块203的块，通常分割成多个不重叠的块。分割单元可以用于对视频序列中所有图片使用相同的块大小以及定义块大小的对应栅格，或用于在图片或子集或图片群组之间更改块大小，并将每个图片分割成对应的块。
在一个实例中，编码器20的预测处理单元260可以用于执行上述分割技术的任何组合。
如图片201，图像块203也是或可以视为具有采样值的采样点的二维阵列或矩阵， 虽然其尺寸比图片201小。换句话说，图像块203可以包括，例如，一个采样阵列(例如黑白图片201情况下的亮度阵列)或三个采样阵列(例如，彩色图片情况下的一个亮度阵列和两个色度阵列)或依据所应用的色彩格式的任何其它数目和/或类别的阵列。图像块203的水平和垂直方向(或轴线)上采样点的数目定义图像块203的尺寸。
如图2所示的编码器20用于逐块编码图片201，例如，对每个图像块203执行编码和预测。
残差计算单元204用于基于图片图像块203和预测块265(下文提供预测块265的其它细节)计算残差块205，例如，通过逐样本(逐像素)将图片图像块203的样本值减去预测块265的样本值，以在样本域中获取残差块205。
变换处理单元206用于在残差块205的样本值上应用例如离散余弦变换(discrete cosine transform，DCT)或离散正弦变换(discrete sine transform，DST)的变换，以在变换域中获取变换系数207。变换系数207也可以称为变换残差系数，并在变换域中表示残差块205。
变换处理单元206可以用于应用DCT/DST的整数近似值，例如为HEVC/H.265指定的变换。与正交DCT变换相比，这种整数近似值通常由某一因子按比例缩放。为了维持经正变换和逆变换处理的残差块的范数，应用额外比例缩放因子作为变换过程的一部分。比例缩放因子通常是基于某些约束条件选择的，例如，比例缩放因子是用于移位运算的2的幂、变换系数的位深度、准确性和实施成本之间的权衡等。例如，在解码器30侧通过例如逆变换处理单元212为逆变换(以及在编码器20侧通过例如逆变换处理单元212为对应逆变换)指定具体比例缩放因子，以及相应地，可以在编码器20侧通过变换处理单元206为正变换指定对应比例缩放因子。
量化单元208用于例如通过应用标量量化或向量量化来量化变换系数207，以获取经量化变换系数209。经量化变换系数209也可以称为经量化残差系数209。量化过程可以减少与部分或全部变换系数207有关的位深度。例如，可在量化期间将n位变换系数向下舍入到m位变换系数，其中n大于m。可通过调整量化参数(quantization parameter，QP)修改量化程度。例如，对于标量量化，可以应用不同的标度来实现较细或较粗的量化。较小量化步长对应较细量化，而较大量化步长对应较粗量化。可以通过量化参数(quantization parameter，QP)指示合适的量化步长。例如，量化参数可以为合适的量化步长的预定义集合的索引。例如，较小的量化参数可以对应精细量化(较小量化步长)，较大量化参数可以对应粗糙量化(较大量化步长)，反之亦然。量化可以包含除以量化步长以及例如通过逆量化210执行的对应的量化或逆量化，或者可以包含乘以量化步长。根据例如HEVC的一些标准的实施例可以使用量化参数来确定量化步长。一般而言，可以基于量化参数使用包含除法的等式的定点近似来计算量化步长。可以引入额外比例缩放因子来进行量化和反量化，以恢复可能由于在用于量化步长和量化参数的等式的定点近似中使用的标度而修改的残差块的范数。在一个实例实施方式中，可以合并逆变换和反量化的标度。或者，可以使用自定义量化表并在例如比特流中将其从编码器通过信号发送到解码器。量化是有损操作，其中量化步长越大，损耗越大。
逆量化单元210用于在经量化系数上应用量化单元208的逆量化，以获取经反量 化系数211，例如，基于或使用与量化单元208相同的量化步长，应用量化单元208应用的量化方案的逆量化方案。经反量化系数211也可以称为经反量化残差系数211，对应于变换系数207，虽然由于量化造成的损耗通常与变换系数不相同。
逆变换处理单元212用于应用变换处理单元206应用的变换的逆变换，例如，逆离散余弦变换(discrete cosine transform，DCT)或逆离散正弦变换(discrete sine transform，DST)，以在样本域中获取逆变换块213。逆变换块213也可以称为逆变换经反量化块213或逆变换残差块213。
重构单元214(例如，求和器214)用于将逆变换块213(即经重构残差块213)添加至预测块265，以在样本域中获取经重构块215，例如，将经重构残差块213的样本值与预测块265的样本值相加。
可选地，例如线缓冲器216的缓冲器单元216(或简称“缓冲器”216)用于缓冲或存储经重构块215和对应的样本值，用于例如帧内预测。在其它的实施例中，编码器可以用于使用存储在缓冲器单元216中的未经滤波的经重构块和/或对应的样本值来进行任何类别的估计和/或预测，例如帧内预测。
例如，编码器20的实施例可以经配置以使得缓冲器单元216不只用于存储用于帧内预测254的经重构块215，也用于环路滤波器单元220(在图2中未示出)，和/或，例如使得缓冲器单元216和经解码图片缓冲器单元230形成一个缓冲器。其它实施例可以用于将经滤波块221和/或来自经解码图片缓冲器230的块或样本(图2中均未示出)用作帧内预测254的输入或基础。解码图片缓冲器230还用于存储知识库图像。针对知识库后续会详细描述，此处不予赘述。
环路滤波器单元220(或简称“环路滤波器”220)用于对经重构块215进行滤波以获取经滤波块221，从而顺利进行像素转变或提高视频质量。环路滤波器单元220旨在表示一个或多个环路滤波器，例如去块滤波器、样本自适应偏移(sample-adaptive offset，SAO)滤波器或其它滤波器，例如双边滤波器、自适应环路滤波器(adaptive loop filter，ALF)，或锐化或平滑滤波器，或协同滤波器。尽管环路滤波器单元220在图2中示出为环内滤波器，但在其它配置中，环路滤波器单元220可实施为环后滤波器。经滤波块221也可以称为经滤波的经重构块221。经解码图片缓冲器230可以在环路滤波器单元220对经重构编码块执行滤波操作之后存储经重构编码块。
编码器20(对应地，环路滤波器单元220)的实施例可以用于输出环路滤波器参数(例如，样本自适应偏移信息)，例如，直接输出或由熵编码单元270或任何其它熵编码单元熵编码后输出，例如使得解码器30可以接收并应用相同的环路滤波器参数用于解码。
经解码图片缓冲器(decoded picture buffer，DPB)230可以为存储参考图片数据供编码器20编码视频数据之用的参考图片存储器。DPB 230可由多种存储器设备中的任一个形成，例如动态随机存储器(dynamic random access memory，DRAM)(包含同步DRAM(synchronous DRAM，SDRAM)、磁阻式RAM(magnetoresistive RAM，MRAM)、电阻式RAM(resistive RAM，RRAM))或其它类型的存储器设备。可以由同一存储器设备或单独的存储器设备提供DPB 230和缓冲器216。在某一实例中， 经解码图片缓冲器(decoded picture buffer，DPB)230用于存储经滤波块221。经解码图片缓冲器230可以进一步用于存储同一当前图片或例如先前经重构图片的不同图片的其它先前的经滤波块，例如先前经重构和经滤波块221，以及可以提供完整的先前经重构亦即经解码图片(和对应参考块和样本)和/或部分经重构当前图片(和对应参考块和样本)，例如用于帧间预测。在某一实例中，如果经重构块215无需环内滤波而得以重构，则经解码图片缓冲器(decoded picture buffer，DPB)230用于存储经重构块215。
预测处理单元260，也称为块预测处理单元260，用于接收或获取图像块203(当前图片201的当前图像块203)和经重构图片数据，例如来自缓冲器216的同一(当前)图片的参考样本和/或来自经解码图片缓冲器230的一个或多个先前经解码图片的参考图片数据231，以及用于处理这类数据进行预测，即提供可以为经帧间预测块245或经帧内预测块255的预测块265。
模式选择单元262可以用于选择预测模式(例如帧内或帧间预测模式)和/或对应的用作预测块265的预测块245或255，以计算残差块205和重构经重构块215。
模式选择单元262的实施例可以用于选择预测模式(例如，从预测处理单元260所支持的那些预测模式中选择)，所述预测模式提供最佳匹配或者说最小残差(最小残差意味着传输或存储中更好的压缩)，或提供最小信令开销(最小信令开销意味着传输或存储中更好的压缩)，或同时考虑或平衡以上两者。模式选择单元262可以用于基于码率失真优化(rate distortion optimization，RDO)确定预测模式，即选择提供最小码率失真优化的预测模式，或选择相关码率失真至少满足预测模式选择标准的预测模式。
下文将详细解释编码器20的实例(例如，通过预测处理单元260)执行的预测处理和(例如，通过模式选择单元262)执行的模式选择。
如上文所述，编码器20用于从(预先确定的)预测模式集合中确定或选择最好或最优的预测模式。预测模式集合可以包括例如帧内预测模式和/或帧间预测模式。
帧内预测模式集合可以包括35种不同的帧内预测模式，例如，如DC(或均值)模式和平面模式的非方向性模式，或如H.265中定义的方向性模式，或者可以包括67种不同的帧内预测模式，例如，如DC(或均值)模式和平面模式的非方向性模式，或如正在发展中的H.266中定义的方向性模式。
在可能的实现中，帧间预测模式集合取决于可用参考图片(即，例如前述存储在DBP 230中的至少部分经解码图片)和其它帧间预测参数，例如取决于是否使用整个参考图片或只使用参考图片的一部分，例如围绕当前块的区域的搜索窗区域，来搜索最佳匹配参考块，和/或例如取决于是否应用如半像素和/或四分之一像素内插的像素内插，帧间预测模式集合例如可包括先进运动矢量(Advanced Motion Vector Prediction，AMVP)模式和融合(merge)模式。具体实施中，帧间预测模式集合可包括本发明实施例改进的基于控制点的AMVP模式，以及，改进的基于控制点的merge模式。在一个实例中，帧内预测单元254可以用于执行下文描述的帧间预测技术的任意组合。
除了以上预测模式，本发明实施例也可以应用跳过模式和/或直接模式。
预测处理单元260可以进一步用于将图像块203分割成较小的块分区或子块，例 如，通过迭代使用四叉树(quad-tree，QT)分割、二进制树(binary-tree，BT)分割或三叉树(triple-tree，TT)分割，或其任何组合，以及用于例如为块分区或子块中的每一个执行预测，其中模式选择包括选择分割的图像块203的树结构和选择应用于块分区或子块中的每一个的预测模式。
帧间预测单元244可以包含运动估计(motion estimation，ME)单元(图2中未示出)和运动补偿(motion compensation，MC)单元(图2中未示出)。运动估计单元用于接收或获取图片图像块203(当前图片201的当前图片图像块203)和经解码图片231，或至少一个或多个先前经重构块，例如，一个或多个其它/不同先前经解码图片231的经重构块，来进行运动估计。例如，视频序列可以包括当前图片和先前经解码图片31，或换句话说，当前图片和先前经解码图片31可以是形成视频序列的图片序列的一部分，或者形成该图片序列。
例如，编码器20可以用于从多个其它图片中的同一或不同图片的多个参考块中选择参考块，并向运动估计单元(图2中未示出)提供参考图片和/或提供参考块的位置(X、Y坐标)与当前块的位置之间的偏移(空间偏移)作为帧间预测参数。该偏移也称为运动向量(motion vector，MV)。
运动补偿单元用于获取帧间预测参数，并基于或使用帧间预测参数执行帧间预测来获取帧间预测块245。由运动补偿单元(图2中未示出)执行的运动补偿可以包含基于通过运动估计(可能执行对子像素精确度的内插)确定的运动/块向量取出或生成预测块。内插滤波可从已知像素样本产生额外像素样本，从而潜在地增加可用于编码图片块的候选预测块的数目。一旦接收到用于当前图片块的PU的运动向量，运动补偿单元246可以在一个参考图片列表中定位运动向量指向的预测块。运动补偿单元246还可以生成与块和视频条带相关联的语法元素，以供解码器30在解码视频条带的图片块时使用。
具体的，上述帧间预测单元244可向熵编码单元270传输语法元素，所述语法元素包括帧间预测参数(比如遍历多个帧间预测模式后选择用于当前块预测的帧间预测模式的指示信息)。可能应用场景中，如果帧间预测模式只有一种，那么也可以不在语法元素中携带帧间预测参数，此时解码端30可直接使用默认的预测模式进行解码。可以理解的，帧间预测单元244可以用于执行帧间预测技术的任意组合。
帧内预测单元254用于获取，例如接收同一图片的图片块203(当前图片块)和一个或多个先前经重构块，例如经重构相相邻块，以进行帧内估计。例如，编码器20可以用于从多个(预定)帧内预测模式中选择帧内预测模式。
编码器20的实施例可以用于基于优化标准选择帧内预测模式，例如基于最小残差(例如，提供最类似于当前图片块203的预测块255的帧内预测模式)或最小码率失真。
帧内预测单元254进一步用于基于如所选择的帧内预测模式的帧内预测参数确定帧内预测块255。在任何情况下，在选择用于块的帧内预测模式之后，帧内预测单元254还用于向熵编码单元270提供帧内预测参数，即提供指示所选择的用于块的帧内预测模式的信息。在一个实例中，帧内预测单元254可以用于执行帧内预测技术的任意组合。
具体的，上述帧内预测单元254可向熵编码单元270传输语法元素，所述语法元素包括帧内预测参数(比如遍历多个帧内预测模式后选择用于当前块预测的帧内预测模式的指示信息)。可能应用场景中，如果帧内预测模式只有一种，那么也可以不在语法元素中携带帧内预测参数，此时解码端30可直接使用默认的预测模式进行解码。
熵编码单元270用于将熵编码算法或方案(例如，可变长度编码(variable length coding，VLC)方案、上下文自适应VLC(context adaptive VLC，CAVLC)方案、算术编码方案、上下文自适应二进制算术编码(context adaptive binary arithmetic coding，CABAC)、基于语法的上下文自适应二进制算术编码(syntax-based context-adaptive binary arithmetic coding，SBAC)、概率区间分割熵(probability interval partitioning entropy，PIPE)编码或其它熵编码方法或技术)应用于经量化残差系数209、帧间预测参数、帧内预测参数和/或环路滤波器参数中的单个或所有上(或不应用)，以获取可以通过输出272以例如经编码比特流21的形式输出的经编码图片数据21。可以将经编码比特流传输到视频解码器30，或将其存档稍后由视频解码器30传输或检索。熵编码单元270还可用于熵编码正被编码的当前视频条带的其它语法元素。
码流封装单元280，用于在确定当前待处理图像所参考的知识库图像与当前待处理图像是同一图像的情况下，将与确定解码当前待处理图像如何参考知识库图像相关的编码信息(比如，第一标识、第二标识、第三标识等等)编入码流(主码流)，并直接通过输出272输出。当确定当前待处理图像所参考的图像与当前待处理图像不为同一图像的情况下，将输出当前图像给残差计算单元204。
视频编码器20的其它结构变型可用于编码视频流。例如，基于非变换的编码器20可以在没有针对某些块或帧的变换处理单元206的情况下直接量化残差信号。在另一实施方式中，编码器20可具有组合成单个单元的量化单元208和逆量化单元210。
具体的，在本发明实施例中，编码器20可用于实现后文实施例中描述的编解码方法。
应当理解的是，视频编码器20的其它的结构变化可用于编码视频流。例如，对于某些图像块或者图像帧，视频编码器20可以直接地量化残差信号而不需要经变换处理单元206处理，相应地也不需要经逆变换处理单元212处理；或者，对于某些图像块或者图像帧，视频编码器20没有产生残差数据，相应地不需要经变换处理单元206、量化单元208、逆量化单元210和逆变换处理单元212处理；或者，视频编码器20可以将经重构图像块作为参考块直接地进行存储而不需要经滤波器220处理；或者，视频编码器20中量化单元208和逆量化单元210可以合并在一起。环路滤波器220是可选的，以及针对无损压缩编码的情况下，变换处理单元206、量化单元208、逆量化单元210和逆变换处理单元212是可选的。应当理解的是，根据不同的应用场景，帧间预测单元244和帧内预测单元254可以是被选择性的启用。
参见图3，图3示出用于实现本发明实施例的解码器30的实例的示意性/概念性框图。视频解码器30用于接收例如由编码器20编码的经编码图片数据(例如，经编码比特流)21，以获取经解码图片231。在解码过程期间，视频解码器30从视频编码器20接收视频数据，例如表示经编码视频条带的图片块的经编码视频比特流及相关联的 语法元素。
在图3的实例中，解码器30包括熵解码单元304、逆量化单元310、逆变换处理单元312、重构单元314(例如求和器314)、缓冲器316、环路滤波器320、经解码图片缓冲器330以及预测处理单元360。预测处理单元360可以包含帧间预测单元344、帧内预测单元354和模式选择单元362。在一些实例中，视频解码器30可执行大体上与参照图2的视频编码器20描述的编码遍次互逆的解码遍次。
熵解码单元304用于对经编码图片数据21执行熵解码，以获取例如经量化系数309和/或经解码的编码参数(图3中未示出)，例如，帧间预测、帧内预测参数、环路滤波器参数和/或其它语法元素中(经解码)的任意一个或全部。熵解码单元304进一步用于将帧间预测参数、帧内预测参数和/或其它语法元素转发至预测处理单元360。视频解码器30可接收视频条带层级和/或视频块层级的语法元素。
逆量化单元310功能上可与逆量化单元110相同，逆变换处理单元312功能上可与逆变换处理单元212相同，重构单元314功能上可与重构单元214相同，缓冲器316功能上可与缓冲器216相同，环路滤波器320功能上可与环路滤波器220相同，经解码图片缓冲器330功能上可与经解码图片缓冲器230相同。
预测处理单元360可以包括帧间预测单元344和帧内预测单元354，其中帧间预测单元344功能上可以类似于帧间预测单元244，帧内预测单元354功能上可以类似于帧内预测单元254。预测处理单元360通常用于执行块预测和/或从经编码数据21获取预测块365，以及从例如熵解码单元304(显式地或隐式地)接收或获取预测相关参数和/或关于所选择的预测模式的信息。
当视频条带经编码为经帧内编码(I)条带时，预测处理单元360的帧内预测单元354用于基于信号表示的帧内预测模式及来自当前帧或图片的先前经解码块的数据来产生用于当前视频条带的图片块的预测块365。当视频帧经编码为经帧间编码(即B或P)条带时，预测处理单元360的帧间预测单元344(例如，运动补偿单元)用于基于运动向量及从熵解码单元304接收的其它语法元素生成用于当前视频条带的视频块的预测块365。对于帧间预测，可从一个参考图片列表内的一个参考图片中产生预测块。视频解码器30可基于存储于DPB 330中的参考图片，使用默认建构技术来建构参考帧列表：列表0和列表1。
预测处理单元360用于通过解析运动向量和其它语法元素，确定用于当前视频条带的视频块的预测信息，并使用预测信息产生用于正经解码的当前视频块的预测块。在本发明的一实例中，预测处理单元360使用接收到的一些语法元素确定用于编码视频条带的视频块的预测模式(例如，帧内或帧间预测)、帧间预测条带类型(例如，B条带、P条带或GPB条带)、用于条带的参考图片列表中的一个或多个的建构信息、用于条带的每个经帧间编码视频块的运动向量、条带的每个经帧间编码视频块的帧间预测状态以及其它信息，以解码当前视频条带的视频块。在本公开的另一实例中，视频解码器30从比特流接收的语法元素包含接收自适应参数集(adaptive parameter set，APS)、序列参数集(sequence parameter set，SPS)、图片参数集(picture parameter set，PPS)或条带标头中的一个或多个中的语法元素。
逆量化单元310可用于逆量化(即，反量化)在比特流中提供且由熵解码单元304 解码的经量化变换系数。逆量化过程可包含使用由视频编码器20针对视频条带中的每一视频块所计算的量化参数来确定应该应用的量化程度并同样确定应该应用的逆量化程度。
逆变换处理单元312用于将逆变换(例如，逆DCT、逆整数变换或概念上类似的逆变换过程)应用于变换系数，以便在像素域中产生残差块。
重构单元314(例如，求和器314)用于将逆变换块313(即经重构残差块313)添加到预测块365，以在样本域中获取经重构块315，例如通过将经重构残差块313的样本值与预测块365的样本值相加。
环路滤波器单元320(在编码循环期间或在编码循环之后)用于对经重构块315进行滤波以获取经滤波块321，从而顺利进行像素转变或提高视频质量。在一个实例中，环路滤波器单元320可以用于执行下文描述的滤波技术的任意组合。环路滤波器单元320旨在表示一个或多个环路滤波器，例如去块滤波器、样本自适应偏移(sample-adaptive offset，SAO)滤波器或其它滤波器，例如双边滤波器、自适应环路滤波器(adaptive loop filter，ALF)，或锐化或平滑滤波器，或协同滤波器。尽管环路滤波器单元320在图3中示出为环内滤波器，但在其它配置中，环路滤波器单元320可实施为环后滤波器。
随后将给定帧或图片中的经解码视频块321存储在存储用于后续运动补偿的参考图片的经解码图片缓冲器330中。解码图片缓冲器330还用于存储知识库图像。
码流解析单元303，在基于知识库的编码方法中，解析主码流中与参考的知识库图像相关的编码信息。当确定当前待处理图像与参考的知识库图像为同一图像的情况下，可以不进行该待处理图像的解码操作，拷贝该知识库图像的解码信息通过输出332输出。
解码器30用于例如，藉由输出332输出经解码图片31，以向用户呈现或供用户查看。
视频解码器30的其它变型可用于对压缩的比特流进行解码。例如，解码器30可以在没有环路滤波器单元320的情况下生成输出视频流。例如，基于非变换的解码器30可以在没有针对某些块或帧的逆变换处理单元312的情况下直接逆量化残差信号。在另一实施方式中，视频解码器30可以具有组合成单个单元的逆量化单元310和逆变换处理单元312。
具体的，在本发明实施例中，解码器30用于实现后文实施例中描述的编解码方法。
应当理解的是，视频解码器30的其它结构变化可用于解码经编码视频位流。例如，视频解码器30可以不经滤波器320处理而生成输出视频流；或者，对于某些图像块或者图像帧，视频解码器30的熵解码单元304没有解码出经量化的系数，相应地不需要经逆量化单元310和逆变换处理单元312处理。环路滤波器320是可选的；以及针对无损压缩的情况下，逆量化单元310和逆变换处理单元312是可选的。应当理解的是，根据不同的应用场景，帧间预测单元和帧内预测单元可以是被选择性的启用。
应当理解的是，本申请的编码器20和解码器30中，针对某个环节的处理结果可以经过进一步处理后，输出到下一个环节，例如，在插值滤波、运动矢量推导或环路 滤波等环节之后，对相应环节的处理结果进一步进行Clip或移位shift等操作。
例如，按照相邻仿射编码块的运动矢量推导得到的当前图像块的控制点的运动矢量，或者推导得到的当前图像块的子块的运动矢量，可以经过进一步处理，本申请对此不做限定。例如，对运动矢量的取值范围进行约束，使其在一定的位宽内。假设允许的运动矢量的位宽为bitDepth，则运动矢量的范围为-2^(bitDepth-1)～2^(bitDepth-1)-1，其中“^”符号表示幂次方。如bitDepth为16，则取值范围为-32768～32767。如bitDepth为18，则取值范围为-131072～131071。又例如，对运动矢量(例如一个8x8图像块内的四个4x4子块的运动矢量MV)的取值进行约束，使得所述四个4x4子块MV的整数部分之间的最大差值不超过N个像素，例如不超过一个像素。
可以通过以下两种方式进行约束，使其在一定的位宽内：
方式1，将运动矢量溢出的高位去除：
ux＝(vx+2 bitDepth)％2 bitDepth
vx＝(ux>＝2 bitDepth-1)？(ux-2 bitDepth):ux
uy＝(vy+2 bitDepth)％2 bitDepth
vy＝(uy>＝2 bitDepth-1)？(uy-2 bitDepth):uy
其中，vx为图像块或所述图像块的子块的运动矢量的水平分量，vy为图像块或所述图像块的子块的运动矢量的垂直分量，ux和uy为中间值；bitDepth表示位宽。
例如vx的值为-32769，通过以上公式得到的为32767。因为在计算机中，数值是以二进制的补码形式存储的，-32769的二进制补码为1,0111,1111,1111,1111(17位)，计算机对于溢出的处理为丢弃高位，则vx的值为0111,1111,1111,1111，则为32767，与通过公式处理得到的结果一致。
方法2，将运动矢量进行Clipping，如以下公式所示：
vx＝Clip3(-2 bitDepth-1,2 bitDepth-1-1,vx)
vy＝Clip3(-2 bitDepth-1,2 bitDepth-1-1,vy)
其中vx为图像块或所述图像块的子块的运动矢量的水平分量，vy为图像块或所述图像块的子块的运动矢量的垂直分量；其中，x、y和z分别对应MV钳位过程Clip3的三个输入值，所述Clip3的定义为，表示将z的值钳位到区间[x,y]之间：
Figure PCTCN2020070520-appb-000001
参见图4，图4是本发明实施例提供的视频译码设备400(例如视频编码设备400 或视频解码设备400)的结构示意图。视频译码设备400适于实施本文所描述的实施例。在一个实施例中，视频译码设备400可以是视频解码器(例如图1A的解码器30)或视频编码器(例如图1A的编码器20)。在另一个实施例中，视频译码设备400可以是上述图1A的解码器30或图1A的编码器20中的一个或多个组件。
视频译码设备400包括：用于接收数据的入口端口410和接收单元(Rx)420，用于处理数据的处理器、逻辑单元或中央处理器(CPU)430，用于传输数据的发射器单元(Tx)440和出口端口450，以及，用于存储数据的存储器460。视频译码设备400还可以包括与入口端口410、接收器单元420、发射器单元440和出口端口450耦合的光电转换组件和电光(EO)组件，用于光信号或电信号的出口或入口。
处理器430通过硬件和软件实现。处理器430可以实现为一个或多个CPU芯片、核(例如，多核处理器)、FPGA、ASIC和DSP。处理器430与入口端口410、接收器单元420、发射器单元440、出口端口450和存储器460通信。处理器430包括译码模块470(例如编码模块470或解码模块470)。编码/解码模块470实现本文中所公开的实施例，以实现本发明实施例所提供的色度块预测方法。例如，编码/解码模块470实现、处理或提供各种编码操作。因此，通过编码/解码模块470为视频译码设备400的功能提供了实质性的改进，并影响了视频译码设备400到不同状态的转换。或者，以存储在存储器460中并由处理器430执行的指令来实现编码/解码模块470。
存储器460包括一个或多个磁盘、磁带机和固态硬盘，可以用作溢出数据存储设备，用于在选择性地执行这些程序时存储程序，并存储在程序执行过程中读取的指令和数据。存储器460可以是易失性和/或非易失性的，可以是只读存储器(ROM)、随机存取存储器(RAM)、随机存取存储器(ternary content-addressable memory，TCAM)和/或静态随机存取存储器(SRAM)。
参见图5，图5是根据一示例性实施例的可用作图1A中的源设备12和目的地设备14中的任一个或两个的装置500的简化框图。装置500可以实现本申请的技术。换言之，图5为本申请实施例的编码设备或解码设备(简称为译码设备500)的一种实现方式的示意性框图。其中，译码设备500可以包括处理器510、存储器530和总线系统550。其中，处理器和存储器通过总线系统相连，该存储器用于存储指令，该处理器用于执行该存储器存储的指令。译码设备的存储器存储程序代码，且处理器可以调用存储器中存储的程序代码执行本申请描述的各种视频编码或解码方法，尤其是各种新的编解码的方法。为避免重复，这里不再详细描述。
在本申请实施例中，该处理器510可以是中央处理单元(Central Processing Unit，简称为“CPU”)，该处理器510还可以是其他通用处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现成可编程门阵列(FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
该存储器530可以包括只读存储器(ROM)设备或者随机存取存储器(RAM)设备。任何其他适宜类型的存储设备也可以用作存储器530。存储器530可以包括由处理器510使用总线550访问的代码和数据531。存储器530可以进一步包括操作系统533 和应用程序535，该应用程序535包括允许处理器510执行本申请描述的视频编码或解码方法(尤其是本申请描述的编解码方法)的至少一个程序。例如，应用程序535可以包括应用1至N，其进一步包括执行在本申请描述的视频编码或解码方法的视频编码或解码应用(简称视频译码应用)。
该总线系统550除包括数据总线之外，还可以包括电源总线、控制总线和状态信号总线等。但是为了清楚说明起见，在图中将各种总线都标为总线系统550。
可选的，译码设备500还可以包括一个或多个输出设备，诸如显示器570。在一个示例中，显示器570可以是触感显示器，其将显示器与可操作地感测触摸输入的触感单元合并。显示器570可以经由总线550连接到处理器510。
下面针对本申请涉及到几个技术概念进行描述。
1)随机访问片段
在视频序列处理中，为了使编码后的视频序列支持随机访问功能，视频序列被分割成多个具有随机访问功能的片段(简称为随机访问片段)。比如：一个视频序列包括至少一个随机访问片段，每个随机访问片段包括一幅随机访问图像以及多幅非随机访问图像。其中，一个随机访问片段中的图像可以进行帧内编码，或者，参考视频序列中的其他图像利用帧间预测进行帧间编码。
2)知识库
为了挖掘和利用多个随机访问片段之间的图像在编码时相互参考的信息，知识库编码方案引入知识库图像(或者简称知识图像)，知识库图像为随机访问片段中当前图像所属的随机访问片段及其之前最邻近的一个随机访问片段中的需要显示的图像集之外的图像，知识图像作为一种参考图像为待编码图像或待解码图像提供参考。存储上述知识库图像的集合的数据库可以称为知识库。另外，这种视频中一幅图像参考至少一幅知识库图像进行编解码的方法可以称为基于知识库的视频编码(英文：library-based video coding)。
为了消除随机访问片段之间的冗余信息，知识库图像将大时间跨度内的多个拥有相关信息的随机访问片段联合起来，剔除了多个随机访问片段之间的冗余信息。在随机访问片段中，提供随机访问能力的图像同样可以参考知识库图像。示例性地，本文将这种所参考的知识库图像称为参考知识库(Reference Library，RL)图像，RL图像在知识库图像可用的情况下提供随机访问能力。
3)参考图像集(reference picture set，rps)
参考图像集可以由当前待处理图像所参考的图像的相关信息构成。参考图像集中可以包括参考的非知识库图像的信息，还可以包括知识库图像的信息。当参考图像集中包括知识库图像时，当前待处理图像可以参考知识库图像采用基于知识库视频编解码方法。
参考图像集，也可以称为参考配置集(reference configure set，rcs)。rcs中可以包括参考图像数目，以及参考配置集中包括的参考图像中的知识库图像的编号等。例如，rcs指示第i个图像是否为知识库图像，第i个图像的编号等。
4)知识库码流
采用基于知识库的视频编码对一个视频序列进行编码时，会产生两个码流，其中一个是包含知识库图像编码的码流，该包含知识库图像编码的码流可以称为知识层码流，另外，一个是包含视频序列各帧图像参考知识库图像编码得到的码流，该包含视频序列各帧图像参考知识库图像编码得到的码流可以称为主码流。此外，知识库图像可以反复被多个主码流的随机访问片段参考。例如，图6展示了一种使用于知识库的视频编码方法得到的主码流图像所属的随机访问片段和知识库图像之间的参考关系，每个知识图像被至少两个不连续的随机访问片段所参考。
在基于知识库的视频编解码时，针对当前待处理图像，从该待处理图像对应的知识库中选择至少一幅图像作为待处理图像的参考图像。对参考图像进行帧内编码，从而获得参考图像的编码数据。根据参考图像的编码数据，重建得到参考图像的重建图像，根据参考图像的重建图像对待处理图像进行帧间编码，从而获得待处理图像的编码数据。，将参考图像的码流数据作为知识层码流发送到解码端。将待处理图像的码流数据作为主码流发送到解码端。解码端在接收到当前待处理图像的主码流后，确定参考知识库图像集中的图像作为参考图像，对参考的知识库图像进行重建，并基于重建的知识库图像对待处理图像进行帧间解码得到待处理图像的重建像素值。解码主码流的待处理图像时,如果该待处理图像参考了知识库中的某一知识库图像,则需要先解码知识层码流中的知识库图像之后才能解码该主码流中的待处理图像。而知识库图像可以是待处理视频序列中的图像，当然获取的知识库图像也可以是待处理视频序列中的图像建模得到的图像和待处理视频序列中的图像合成的图像。也就是说针对当前待处理图像选择的所参考的知识库图像可能与当前待处理图像是同一幅图像，在情况下，编解码完该参考的知识库图像后，实际上并不需要再额外编解码该主码流中的待处理图像，因此，现有的基于知识库的视频编解码方法中，针对当前待处理图像选择的所参考的知识库图像可能与当前待处理图像是同一幅图像的情况下，编解码完该参考的知识库图像后，再额外编解码该主码流中的待处理图像的方式存在冗余。
基于此，本申请提出了一种视频图像编码、解码方法及装置，针对当前待处理图像选择的所参考的知识库图像可能与当前待处理图像是同一幅图像的情况下，编解码完该参考的知识库图像后，不再额外编解码该主码流中的待处理图像，而是基于简单拷贝参考的知识库图像的解码数据确定该主码流中待处理图像的解码数据，从而可以避免现有的冗余编码方式，节省传输资源。其中，方法和装置是基于同一发明构思的，由于方法及装置解决问题的原理相似，因此装置与方法的实施可以相互参见，重复之处不再赘述。
另外，需要说明的是，本申请中，“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况，其中A,B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a,b,或c中的至少一项(个)，可以表示：a,b,c,a-b,a-c,b-c,或a-b-c，其中a,b,c可以是单个，也可以是多个。
下面详细阐述本申请实施例的方案：
为了挖掘和利用多个随机访问片段之间的图像在编码时相互参考的信息，在编码(或解码)一幅图像时，编码器(或解码器)可以从数据库中选择与当前编码图像(或解码图像)纹理内容相近的图像作为参考图像，这种参考图像称为知识库图像，存储上述参考图像的集合的数据库称为知识库，这种视频中至少一幅图像参考至少一幅知识库图像进行编解码的方法称为基于知识库的视频编码(英文：library-based video coding)。采用基于知识库的视频编码对一个视频序列进行编码会产生一个包含知识库图像编码码流的知识层码流和一个包含视频序列各帧图像参考知识库图像编码得到的码流的视频层码流。这两种码流分别类似于可伸缩视频编码(英文：scalable video coding，SVC)产生的基本层码流和增强层码流，即序列层码流依赖于知识层码流。然而，基于知识库的视频编码的双码流组织方式与SVC的分级码流组织方式的层级码流之间的依赖关系不同，不同之处在于，SVC的双码流层级之间是按照一定的对齐时间段依赖的，而基于知识库的视频编码的双码流中视频层依赖知识层是按照非对齐时间段依赖的。
对于使用基于知识库的视频编码方法编码会得到两个码流，知识库码流和视频主码流，视频主码流的解码必须依赖知识库码流。当解码主码流视频帧时，如果该帧参考了知识库码流中的某一帧,则需要先解码知识库码流中的帧之后才能解码该主码流中的视频帧。当主码流中按解码顺序排列相近的两帧参考了不同的知识库码流帧时，则会产生一个解码峰值，对解码器产生解码冲击。
示例1：
在语法中增加限定时间的语法元素，并限定语法元素在不同profile和level中的取值范围。在AVS3中，语法元素如下表所示。
Figure PCTCN2020070520-appb-000002
其中新增的语法元素的语义为：
library_picture_enable_flag：1比特标识符。当值为1时，表示当前码流参考外部的知识层码流；当值为0时，表示当前码流不参考知识层码流。该字段的比特数以及表示不同含义的取值可以被自由定义和设计，本发明中不做限定。
min_library_interval_time：12比特位。描述当前码流参考的知识图像的最小解码时间间隔，其值域范围由profile和level限制。其中，高6位描述0～59之间的值，单位为秒，低6位描述0～63之间的值，当帧率小于64时，单位为图像，否则，单位是1/64秒。
在一种可行的实施例中，min_library_interval_time的语义可以为：固定比特长度或可变比特长度的符号，描述当前码流参考的知识图像的最小解码时间间隔，例如语法元素的各个比特位分别描述时分秒、又例如语法元素描述以秒为单位的个数、又例如语法元素描述以图像为单位的个数，其值域范围由profile和level限制，其中不同的profile和level可以确定最小解码时间间隔能够取值范围的下限。
具体地，在一种可能的实现过程中，编码器端可以执行如下操作：
1.初始化主码流图像编码时可参考的知识图像集合L(集合L中的知识图像均可用且已被重建得到重建像素)，集合L包括整个主码流可以使用的所有的知识图像；初始化前一个(上一个)参考新的知识图像的主码流图像(这里的前一个是依据编码时序确定的)的编码时刻tj为T，其初始化值应保证编码的第一个主码流图像(编码时刻为0秒)能够使用任意知识图像作为候选参考图像(例如不大于-k秒，使得第一个主码流图像的编码时刻0与T的差值不小于k秒)，k秒的值域范围以及k秒内能够解码的图像数目fk+N的值域范围(即最多允许比主码流的图像数fk多解码N个图像)可以由profile和level限制，根据k的值确定min_library_interval_time的值。
例如min_library_interval_time的值等于k的值，
又例如min_library_interval_time的值等于k-1的值以保证min_library_interval_time的值从0开始，
又例如min_library_interval_time的值等于log2(k)的值以减少min_library_interval_time占用的比特数)，
并将min_library_interval_time放入码流的序列头；
2.当编码第i个主码流图像时；
a)如果当前编码图像参考知识图像(eg，通过对比编码图像参考知识图像的编码效率和参考短期参考图像的编码效率的对比判断当前图像是否参考知识图像；具体实现过程中，当码流允许参考知识图像时(如library_picture_enable_flag为1)，任意一个图像都有一个对应的字段表示该图像是否参考了知识图像，如该字段可以是该图像的字段，也可以是标准允许的默认继承自别的图像的字段；该步骤可以采用现有技术手段，本发明中不予以赘述)，执行以下操作之一：
1)从知识图像集合L中选择m(m>0)个知识图像，所述m个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；或者，
2)检查当前编码图像的编码时刻ti(可以通过编码计时获得；也可以码流中传输当前编码图像的显示时间Ti和显示时间与编码时间的差值△Ti，以使解码端根据得到Ti和△Ti得到ti；其中，不同编码图像对应的Ti和△Ti可以 相同也可以不相同，本发明不做限定；或者现有技术的其他方式，应理解码流中的编码信息可以用于约束实际的解码时刻)与T的差值是否大于k。
当ti-tj>＝k时：
[1]从知识图像集合L中选择m(m>0)个知识图像，并选择n(0<n<N)个不在集合L中的知识图像，所述m+n个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；或者，
[2]选择n(0<n<N)个不在集合L中的知识图像，所述n个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；
其中，上述选择知识图像(从知识图像集合L中选择m(m>0)个知识图像的操作)的操作方法包括但不限于：
(a1)根据第i个主码流图像与集合L中知识图像的内容相似性选择相似性最高的m个知识图像；
(b1)当集合L中知识图像是从视频序列中的用于呈现的图像中抽取得到的(即一个知识图像与视频序列中某一呈现时刻的图像的内容完全相同)，根据第i个主码流图像的呈现时刻与集合L中知识图像在视频中对应的呈现时刻的差异大小选择差异最小(即时间上更临近)的m个知识图像；
(c1)根据第i个主码流图像使用集合L中知识图像作为参考图像进行编码的编码效率，以选择编码效率最高的m个知识图像。
其中，上述选择知识图像(从不在集合L中的知识图像中选择n(0<n<N)个知识图像的操作)的操作方法包括但不限于：
(a2)根据第i个主码流图像与不在集合L中的知识图像的内容相似性选择相似性最高的n个知识图像；
(b2)当集合L中知识图像是从视频序列中的用于呈现的图像中抽取得到的(即一个知识图像与视频序列中某一呈现时刻的图像的内容完全相同)，根据第i个主码流图像的呈现时刻与不在集合L中的知识图像在视频中对应的呈现时刻的差异大小选择差异最小(即时间上更临近)的n个知识图像；
(c2)根据第i个主码流图像使用不在集合L中的知识图像作为参考图像进行编码的编码效率，以选择编码效率最高的或n个知识图像。
其中，所述集合L中的知识图像已经被重建，而不在集合L中的知识图像是未被重建或需要被重新重建的，其中，重新被重建的知识图像满足以下一个或多个条件：
已经被重建的知识图像由于缓存容量不足而被删除或替换；或，
已经被重建的知识图像由于缓存内容出错而被破坏；或，
已经被重建的知识图像由于管理操作错误而被删除或替换；或，
已经被重建的知识图像由于超出其生命周期而被删除或替换，但是由于回看或跳转等操作又需要被参考。
其中，短期参考图像为第i个主码流图像之前已经编码的在时间上临近第i个主码流图像且可以被第i个主码流图像作为候选参考图像的主码流图 像(例如0～i-1之间的已解码的主码流图像)的重建图像。
b)如果当前编码图像不参考知识图像，此时m＝0且n＝0，由当前编码图像的短期参考图像构成参考图像集合。
3.使用参考图像集合作为第i个编码图像的候选参考图像以对第i个编码图像进行编码。例如，当m+n>0时，被选中的m+n个知识图像作为新的可参考的知识图像集合L。
4.如果第i个主码流图像不是序列中最后一个图像，返回步骤2，如果当n大于0的时候，则对于下一个主码流图像(在代码实现中，将i＝i+1，即执行下一个主码流图像)，将tj的值更新为ti；否则，即第i个主码流图像是序列中最后一个图像，则结束编码过程。
一种实例中，应理解，在解码顺序之前与当前解码图像(解码时刻ti)最邻近的一个参考了至少一个新的知识图像(n大于0)的解码图像的解码时刻可以表示为tj，其中所述新知识图像为与次临近的一个参考知识图像的解码图像所参考的知识图像不同的知识图像；随着新的知识图像的出现，tj也会进行更新；更为具体地，tj的第一个取值初始化为T，即T可以理解为一个图像序列的起始图像的解码时刻初始值，可以由用户根据需要定义，随着解码的不断进行，tj会随着参考了新的知识图像的解码图像的解码而进行“更替”，应理解，更替间隔并不唯一。
具体地，在一种可能的实现过程中，解码器端可以执行如下操作：
1.接收基于知识库的视频编码方法编码得到的码流；
2.从序列头中解析min_library_interval_time，以获得码流中允许的知识图像的最小解码时间间隔k秒，则该码流满足以下条件，且解码器需要在k秒内解码fk+N个图像(例如N＝1)，其中f是帧率，fk表示的是主码流解码图像；
对于一个参考了知识图像的主码流图像A，和另一个参考了知识图像的主码流图像B，如果A和B参考的知识图像中有n个最多有N个不相同的知识图像，则A和B之间的图像数目不少于以码流中声明的视频序列的帧率f对应的k秒的图像数，举例的k值为1。
3.根据序列头中的profile和level的信息，获取当前码流符合的profile和level允许的最小解码时间间隔的下限以及当前profile和level下能够解码的图像数目fk+N的值域范围(即最多允许比主码流的图像数fk多解码N个图像)，
当k不小于该下限时，解码器确定当前码流符合解码器支持的编解码标准，并执行步骤4；
当k小于该下限，判定接收的码流不合法，终止或暂停解码。
4.根据解码器在k秒内能够解码的最大图像数目q，确定解码器能否实时解码播放当前码流，当q不小于fk+N时，解码器执行以下解码操作；当q小于fk+N时，则暂停解码或终止解码。
a)初始化前一个参考了新的知识图像的主码流图像的解码时刻tj为T，其初始化值应保证待解码的第一个主码流图像(解码时刻为0秒)能够使用任意的知识图像作为候选参考图像(例如不大于-k秒，使得第一个主码流图像的解码时刻0与T的差值不小于k秒)，
b)对于第i个主码流图像，
i.如果该图像参考知识图像，执行以下操作之一：
[1]如果该图像的参考图像集合/配置集中有m(m>0)个知识图像来自知识图像集合L，且有0个知识图像不在集合L中，则不需要解码新的知识图像，并以所述m个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；或者，
[2]如果该图像的参考图像集合中有m(m>0)个知识图像来自知识图像集合L，且有n(0<n<N)个知识图像不在集合L中，则，检查当前解码图像的解码时刻ti与T的差值是否大于k，
当ti-tj>＝k时，解码所述n个知识图像，并以所述m+n个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；
当ti-tj<k时，判定接收的码流不合法，终止或暂停解码。或者，
[3]如果该图像的参考图像集合中有0个知识图像来自知识图像集合L，且有n(0<n<N)个知识图像不在集合L中，则，检查当前解码图像的解码时刻ti与T的差值是否大于k，
当ti-tj>＝k时，解码所述n个知识图像，并以所述n个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；
当ti-tj<k时，判定接收的码流不合法，终止或暂停解码。
其中，集合L中的知识图像均可用且已被解码，而不在集合L中的知识图像是未被解码或需要被重新解码的。
已经被解码的知识图像由于缓存容量不足而被删除或替换；或，
已经被解码的知识图像由于缓存内容出错而被破坏；或，
已经被解码的知识图像由于管理操作错误而被删除或替换；或，
已经被解码的知识图像由于超出其生命周期而被删除或替换，但是由于回看或跳转等操作又需要被参考。
应理解，任意图像的解码时刻ti是可以根据码流中的信息进而获取到的，也可以是解码器根据实际情况获得的，本发明不做限定和约束。
ii.如果该图像不参考知识图像(即m＝0且n＝0)，由当前编码图像的短期参考图像构成参考图像集合；
c)使用参考图像集合作为第i个图像的候选参考图像以对第i个图像进行解码。
d)如果第i个主码流图像不是序列中最后一个图像，返回上一步骤，并将i＝i+1；
否则，结束解码过程。
示例2：
在HEVC和VVC中，在vps中的语法元素如下表所示。
Figure PCTCN2020070520-appb-000003
Figure PCTCN2020070520-appb-000004
其中新增的语法元素的语义为：
vps_library_picture_enable_flag：1比特标识符。当值为1时，表示当前码流参考外部的知识层码流；当值为0时，表示当前码流不参考知识层码流。该字段的比特数以及表示不同含义的取值可以被自由定义和设计，本发明中不做限定。
min_library_interval_time：12比特位。描述当前码流参考的知识图像的最小解码时间间隔，其值域范围由profile和level限制。其中，高6位描述0～59之间的值，单位为秒，低6位描述0～63之间的值，当帧率小于64时，单位为图像，否则，单位是1/64秒。
在一种可行的实施例中，min_library_interval_time的语义可以为：固定比特长度或可变比特长度的符号，描述当前码流参考的知识图像的最小解码时间间隔，例如语法元素的各个比特位分别描述时分秒、又例如语法元素描述以秒为单位的个数、又例如语法元素描述以图像为单位的个数，其值域范围由profile和level限制，其中不同的profile和level可以确定最小解码时间间隔能够取值范围的下限。
具体地，在一种可能的实现过程中，编码器端可以执行如示例1中编码器的操作：解码器端可以执行如示例1中解码器的操作。
示例3：
在HEVC和VVC中，在sps中的语法元素如下表所示。
Figure PCTCN2020070520-appb-000005
其中新增的语法元素的语义为：
sps_library_picture_enable_flag：1比特标识符。当值为1时，表示当前码流参考外部的知识层码流；当值为0时，表示当前码流不参考知识层码流。该字段的比特数以及表示不同含义的取值可以被自由定义和设计，本发明中不做限定。
min_library_interval_time：12比特位。描述当前码流参考的知识图像的最小解码时间间隔，其值域范围由profile和level限制。其中，高6位描述0～59之间的值，单位为秒，低6位描述0～63之间的值，当帧率小于64时，单位为图像，否则，单位是1/64秒。
在一种可行的实施例中，min_library_interval_time的语义可以为：固定比特长度或可变比特长度的符号，描述当前码流参考的知识图像的最小解码时间间隔，例如语法元素的各个比特位分别描述时分秒、又例如语法元素描述以秒为单位的个数、又例如语法元素描述以图像为单位的个数，其值域范围由profile和level限制，其中不同的profile和level可以确定最小解码时间间隔能够取值范围的下限。
具体地，在一种可能的实现过程中，编码器端可以执行如示例1中编码器的操作：解码器端可以执行如示例1中解码器的操作。
更为具体地，本发明中可能的设计中包括如下实施方式：
实施例1：
限制视频主码流图像参考知识库图像的最小时间间隔：
方案1：对于一个参考了知识库图像的主码流图像A，和另一个参考了知识库图像的主码流图像B，如果A和B参考的知识库图像不相同(一个或多个不同)，则：
A和B之间的图像数目不少于以码流中声明的视频序列的帧率对应的k秒的图像数，举例的k值为1。
编码器执行以下操作：
S1，初始化前一个参考知识图像的主码流图像的编码时刻T，其初始化值不大于-k；初始化主码流图像编码时可参考的知识图像集合L为无穷大；
S2，当编码第i个主码流图像时，检查当前编码图像的编码时刻ti与T的差值是否大于k；
当ti-T>＝k时，从知识图像集合L中选择m(m>＝0)个知识图像，并选择n(n>＝0)个不在集合L中的知识图像，所述m+n个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；
当ti-T<k时，从知识图像集合L中选择m(m>＝0)个知识图像，所述m个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；
S3，使用参考图像集合对第i个编码图像进行编码。当n>0时，被选中的n个知识图像作为新的可参考的知识图像集合L，并将T的值更新为ti；当n＝0时，T不变。
S4，如果第i个主码流图像不是序列中最后一个图像，返回步骤2，并将i＝i+1；否则，结束编码过程。
上述编码器产生的码流结构请参阅图6A所示，
在上述示例码流中，L*为知识图像，R*表示参考知识图像的编码图像，N*表示不参考知识图像的编码图像。生成上述示例码流的编码器执行如下示例操作(为了描述方便，R图像和N图像参考的短期参考图像不再赘述)：
假设k＝3，n<＝1；
初始化T＝-k，知识图像集合L＝∞为无穷大；
由于0-T>＝k，R0从知识图像集合L中选择L0作为参考图像，并编码，更新T＝0，知识图像集合L＝{L0}；
N1和N2不参考知识图像；
由于3-T>＝k，R3从知识图像集合L中选择L0(全部集合图像)作为参考图像，并选择不属于知识图像集合L的L1作为参考图像，并编码，更新T＝3，知识图像集合L＝{L0,L1}；
N4和N5不参考知识图像；
由于6-T>＝k，R6从知识图像集合L中选择L0(子集图像)作为参考图像，并选择不属于知识图像集合L的L2作为参考图像，并编码，更新T＝6，知识图像集合L＝{L0,L2}；
N7不参考知识图像；
由于8-T<k，R8从知识图像集合L中选择L2作为参考图像(而不能选择不属于知识图像集合L的知识图像作为参考图像)，并编码，更新T＝8，知识图像集合L＝{L2}；
N9和N10不参考知识图像；
由于11-T>＝k，R11从知识图像集合L中选择L2(全部集合图像)作为参考图像，并选择不属于知识图像集合L的L3作为参考图像，并编码，更新T＝11，知识图像集合L＝{L2,L3}；
结束编码。
解码器执行以下操作：
接收基于知识库的视频编码方法编码得到的码流，该码流满足以下条件，则解码器需要在k秒内解码fk+n个图像；
a)对于一个参考了知识图像的主码流图像A，和另一个参考了知识图像的主码流图像B，如果A和B参考的知识图像中有n个不相同的知识图像，则A和B之间的图像数目不少于以码流中声明的视频序列的帧率f对应的k秒的图像数，举例的k值为1。
对于第i个主码流图像，
a)如果该图像参考知识图像，则解码其中相较于之前主码流图像参考的知识图像中新增的知识图像，所述新增的知识图像最多为n个；使用上述知识图像为参考图像以解码该主码流图像；
b)如果该图像不参考知识图像，则解码该主码流图像；
如果第i个主码流图像不是序列中最后一个图像，返回上一步骤，并将i＝i+1；否则，结束解码过程。
例如，当解码器(限定k秒最多解1个知识图像)接收到如图6B码流时，解码器能够完成实时解码：
例如，当解码器(限定k秒最多解1个知识图像)接收到如图6C码流时，解码器不能够完成实时解码R3和R8，因为尽管R3与R0的时间间隔超过k秒，但是R3参考的知识图像比R0多3个；而尽管R8参考的知识图像与R6参考的知识图像只有 一个不同，但是R8和R6之间的时间间隔小于k秒。
实施例2：
对于一个参考知识图像的编码图像A，记在A解码之前解码的一个参考知识图像的编码图像为B，A应该满足以下所有条件：
码流顺序在A和B之间的编码图像均不参考知识图像；
A所参考的知识图像应最多有n个不是B参考的知识图像；
当A所参考的知识图像中有n个不是B参考的知识图像时,在A和B之间解码的图像的数目至少为以码流中声明的视频序列的帧率对应的k秒钟的图像数。其中k秒限制的影响在于：每k秒比帧率增加n个图像的解码能力。
编码器执行以下操作：
S1.初始化前一个参考知识图像的主码流图像的编码时刻T，其初始化值不大于-k；初始化主码流图像编码时可参考的知识图像集合L为无穷大；
S2.当编码第i个主码流图像时，检查当前编码图像的编码时刻ti与T的差值是否大于k；
a)当ti-T>＝k时，从知识图像集合L中选择m(m>＝0)个知识图像，并选择n(n>＝0)个不在集合L中的知识图像，所述m+n个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；
b)当ti-T<k时，仅选择第i个主码流图像的短期参考图像构成参考图像集合；
S3.使用参考图像集合对第i个编码图像进行编码。当m+n>0时，被选中的m+n个知识图像作为新的可参考的知识图像集合L，并将T的值更新为ti。
S4.如果第i个主码流图像不是序列中最后一个图像，返回步骤2，并将i＝i+1；否则，结束编码过程。
上述编码器产生的码流可以参见图7A；在该示例码流中，L*为知识图像，R*表示参考知识图像的编码图像，N*表示不参考知识图像的编码图像。
解码器执行以下操作：
接收基于知识库的视频编码方法编码得到的码流，该码流满足以下条件，则解码器需要在k秒内解码fk+n个图像；
a)对于一个参考了知识图像的主码流图像A，和另一个参考了知识图像的主码流图像B，A与B之间的图像不参考知识图像。如果A和B参考的知识图像中有n个不相同的知识图像，则A和B之间的图像数目不少于以码流中声明的视频序列的帧率f对应的k秒的图像数，举例的k值为1。
对于第i个主码流图像，
a)如果该图像参考知识图像，则解码其中相较于之前主码流图像参考的知识图像中新增的知识图像，所述新增的知识图像最多为n个；使用上述知识图像为参考图像以解码该主码流图像；
b)如果该图像不参考知识图像，则解码该主码流图像；
如果第i个主码流图像不是序列中最后一个图像，返回上一步骤，并将i＝i+1；否则，结束解码过程。
例如，当解码器(限定k秒最多解1个知识图像)接收到如图7B码流时，解码器能够完成实时解码：
例如，当解码器(限定k秒最多解1个知识图像)接收到如图7C码流时，解码器不能够完成实时解码R3和R8，因为尽管R3与R0的时间间隔超过k秒，但是R3参考的知识图像比R0多3个；而尽管R8参考的知识图像为R6参考的知识图像的子集(没有导致新的知识图像的解码)，但是R8和R6之间的时间间隔小于k秒。
实施例3：
对于一个参考知识图像的编码图像A，记在A解码之前解码的一个参考知识图像的编码图像为B，A应该满足以下所有条件：
码流顺序在A和B之间的编码图像如果参考知识图像，其所参考的知识图像均应是B参考的知识图像或其子集；
A所参考的知识图像应最多有一个不是B参考的知识图像；
在A和B之间解码的图像的数目至少为以码流中声明的视频序列的帧率对应的T秒的图像数。其中T秒限制的影响在于：每T秒比帧率增加一个图像的解码能力。
编码器执行以下操作：
1.初始化前一个参考知识图像的主码流图像的编码时刻T，其初始化值不大于-k；初始化主码流图像编码时可参考的知识图像集合L为无穷大；
2.当编码第i个主码流图像时，检查当前编码图像的编码时刻ti与T的差值是否大于k；
a)当ti-T>＝k时，从知识图像集合L中选择m(m>＝0)个知识图像，并选择n(n>＝0)个不在集合L中的知识图像，所述m+n个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；当m+n>0时，被选中的m+n个知识图像作为新的可参考的知识图像集合L，并将T的值更新为ti；
b)当ti-T<k时，从知识图像集合L中选择m(m>＝0)个知识图像，所述m个知识图像与第i个主码流图像的短期参考图像构成参考图像集合；
3.使用参考图像集合对第i个编码图像进行编码。
4.如果第i个主码流图像不是序列中最后一个图像，返回步骤2，并将i＝i+1；否则，结束编码过程。
上述编码器产生的码流结构可以参考图8A；在该示例码流中，L*为知识图像，R*表示参考知识图像的编码图像，N*表示不参考知识图像的编码图像。
解码器执行以下操作：
接收基于知识库的视频编码方法编码得到的码流，该码流满足以下条件，则解码 器需要在k秒内解码fk+n个图像；
a)对于一个参考了知识图像的主码流图像A，和另一个参考了知识图像的主码流图像B，A与B之间的图像仅参考A参考的知识图像或其子集。如果A和B参考的知识图像中有n个不相同的知识图像，则A和B之间的图像数目不少于以码流中声明的视频序列的帧率f对应的k秒的图像数，举例的k值为1。
对于第i个主码流图像，
a)如果该图像参考知识图像，则解码其中相较于之前主码流图像参考的知识图像中新增的知识图像，所述新增的知识图像最多为n个；使用上述知识图像为参考图像以解码该主码流图像；
b)如果该图像不参考知识图像，则解码该主码流图像；
如果第i个主码流图像不是序列中最后一个图像，返回上一步骤，并将i＝i+1；否则，结束解码过程。
例如，当解码器(限定k秒最多解1个知识图像)接收到如图8B所示的码流时，解码器能够完成实时解码；
例如，当解码器(限定k秒最多解1个知识图像)接收到如图8C所示的码流时，解码器不能够完成实时解码R3和R8，因为尽管R3与R0的时间间隔超过k秒，但是R3参考的知识图像比R0多3个；而尽管R8参考的知识图像与R6参考的知识图像只有一个不同，但是R8和R6之间的时间间隔小于k秒。
实施例4：
对于紧随序列头后的支持随机访问且仅参考知识图像的RL图像A，记在码流中A之前第一个、紧随序列头后的RL图像为B。A应满足以下所有条件：
A所参考的知识图像最多只有一个不是B所参考的知识图像，
在A和B之间解码的图像的数目至少为以码流中声明的视频序列的帧率对应的T秒钟的图像数。其中k秒限制的影响在于：每k秒比帧率增加一个图像的解码能力。
编码器执行以下操作：
1.初始化前一个参考知识图像的主码流图像的编码时刻T，其初始化值不大于-k；初始化主码流图像编码时可参考的知识图像集合L为无穷大；
2.当编码第i个主码流图像时，
a)如果当前图像是RL图像，检查当前编码图像的编码时刻ti与T的差值是否大于k，
1)当ti-T>＝k时，从知识图像集合L中选择m(m>＝0)个知识图像，并选择n(n>＝0)个不在集合L中的知识图像，所述m+n个知识图像构成参考图像集合；当m+n>0时，被选中的m+n个知识图像作为新的可参考的知识图像集合L，并将T的值更新为ti；
2)当ti-T<k时，从知识图像集合L中选择m(m>＝0)个知识图像，所述m个知识图像构成参考图像集合；
b)如果当前图像不是RL图像，从知识图像集合L中选择m(m>＝0)个知识图 像，所述m个知识图像构成参考图像集合；
3.使用参考图像集合对第i个编码图像进行编码。
4.如果第i个主码流图像不是序列中最后一个图像，返回步骤2，并将i＝i+1；否则，结束编码过程。
上述编码器产生的码流结构可以如图9A所示，在该示例码流中，L*为知识图像，R*表示参考知识图像的编码图像，RL*表示仅参考知识图像的编码图像，N*表示不参考知识图像的编码图像。
解码器执行以下操作：
S1，接收基于知识库的视频编码方法编码得到的码流，该码流满足以下条件，则解码器需要在k秒内解码fk+n个图像；
a)对于紧随序列头后的支持随机访问且仅参考知识图像的RL图像A，记在码流中A之前第一个、紧随序列头后的RL图像为B。A所参考的知识图像最多只有n个不是B所参考的知识图像；在A和B之间解码的图像的数目至少为以码流中声明的视频序列的帧率f对应的k秒钟的图像数。其中k秒限制的影响在于：每k秒比帧率增加一个图像的解码能力。
S2，对于第i个主码流图像，
a)如果该图像参考知识图像，则解码其中相较于之前主码流图像参考的知识图像中新增的知识图像，所述新增的知识图像最多为n个；使用上述知识图像为参考图像以解码该主码流图像；
b)如果该图像不参考知识图像，则解码该主码流图像；
S3，如果第i个主码流图像不是序列中最后一个图像，返回上一步骤，并将i＝i+1；否则，结束解码过程。
例如，当解码器(限定k秒最多解1个知识图像)接收到如图9B所示码流时，解码器能够完成实时解码；
例如，当解码器(限定k秒最多解1个知识图像)接收到如图9C所示码流时，解码器不能够完成实时解码R2和R8，因为尽管RL2参考的知识图像与RL0参考的知识图像只有1个不同，但是RL2和RL0之间的时间间隔小于k秒；尽管R8与R5的时间间隔超过k秒，但是RL8参考的知识图像比RL0多2个。
结合以上实例，请参阅图9D，本申请公开了一种可选的解码方法9000，包括以下步骤：
S9001，获取第一解码图像；第一解码图像为主码流中在当前待解码图像之前最近的一个紧随序列头后的支持随机访问且仅参考知识图像的图像。
其中，第一解码图像可以理解为但不限于上述实施例中的图像B，当前待解码图像可以理解为但不限于上述实施例中的图像A。
S9002，将新知识图像作为当前待解码图像的参考图像；当前待解码图像为支持随机访问且仅参考知识图像的图像。
其中，在主码流中，当前待解码图像和第一解码图像之间解码的图像的数目至少 为f*k；例如但不限于f*k+n；k为主码流允许的知识图像之间的最小解码时间间隔；f为主码流中声明的视频序列的帧率；新知识图像的个数不大于预设值n；n为正整数；上述新知识图像为当前待解码图像(如图像A)参考的知识图像中没有被第一解码图像(如图像B)所参考的知识图像；新知识图像是通过解码知识库码流得到的。可选的，n的取值可以包括但不限于1、2；新知识图像可以通过解码知识库码流得到。
进一步地，上述方法900还可以包括：
S9003，根据上述新知识图像解码当前待解码图像。
对应地，上述方法9000可以在设备1000(如图12)执行或应用。具体的，第二获取模块1002可以执行上述S9001；确定模块1003可以执行上述S9002。
在具体实现过程中，设备1000还可以包括解码模块1004(图12中未视出)，具体可以执行上述S9003。
实施例5：
对于位流中紧随两个连续的序列头之后的RL图像(能参考知识图像同时支持随机访问)，在位流中较后的RL图像最多只能参考一个不同于在位流中较前的RL图像所参考的知识图像。并且当位流中较后的RL图像参考了一个不同于位流中较前的RL图像所参考的知识图像之时，所述的两个连续的序列头之间应至少包含T秒钟的显示图像。其中T秒限制的影响在于：每T秒比帧率增加一个图像的解码能力。
编码器执行以下操作：
1.初始化前一个参考知识图像的主码流图像的编码时刻T，其初始化值不大于-k；初始化主码流图像编码时可参考的知识图像集合L为无穷大；
2.当编码第i个主码流图像时，
a)如果当前图像是RL图像，且该RL图像不是第一个RL图像，检查当前编码图像的编码时刻ti与T的差值是否大于k，
1)当ti-T>＝k时，从知识图像集合L中选择m(m>＝0)个知识图像，并选择n(n>＝0)个不在集合L中的知识图像，所述m+n个知识图像构成参考图像集合；当m+n>0时，被选中的m+n个知识图像作为新的可参考的知识图像集合L，并将T的值更新为ti；
2)当ti-T<k时，从知识图像集合L中选择m(m>＝0)个知识图像，所述m个知识图像构成参考图像集合；
b)如果当前图像不是RL图像，从知识图像集合L中选择m(m>＝0)个知识图像，所述m个知识图像构成参考图像集合；
3.使用参考图像集合对第i个编码图像进行编码。
4.如果第i个主码流图像不是序列中最后一个图像，返回步骤2，并将i＝i+1；否则，结束编码过程。
上述编码器产生的码流结构示例如图10A所示，其中RL3和RL0之间没有上述解码限制。在该示例码流中，L*为知识图像，R*表示参考知识图像的编码图像，RL* 表示仅参考知识图像的编码图像，N*表示不参考知识图像的编码图像。
解码器执行以下操作：
接收基于知识库的视频编码方法编码得到的码流，该码流满足以下条件，则解码器需要在k秒内解码fk+n个图像；
a)对于位流中紧随两个连续的序列头之后的支持随机访问且仅参考知识图像的RL图像A，记在码流中A之前第一个、紧随序列头后的RL图像为B。A所参考的知识图像最多只有n个不是B所参考的知识图像；在A和B之间解码的图像的数目至少为以码流中声明的视频序列的帧率f对应的k秒钟的图像数。其中k秒限制的影响在于：每k秒比帧率增加一个图像的解码能力。
对于第i个主码流图像，
a)如果该图像参考知识图像，则解码其中相较于之前主码流图像参考的知识图像中新增的知识图像，所述新增的知识图像最多为n个；使用上述知识图像为参考图像以解码该主码流图像；
b)如果该图像不参考知识图像，则解码该主码流图像；
如果第i个主码流图像不是序列中最后一个图像，返回上一步骤，并将i＝i+1；否则，结束解码过程。
例如，当解码器(限定k秒最多解1个知识图像)接收到如图10B所示码流时，解码器能够完成实时解码，则是因为尽管RL0参考多个知识图像，但是由于启动延时的允许，RL0的知识图像的解码时间可以通过增加启动延时来获得，因此尽管RL3参考的知识图像比RL0的知识图像多2个，但是RL3的知识图像的解码时间不受到RL0和RL3之间的时间间隔约束；
例如，当解码器(限定k秒最多解1个知识图像)接收到如图10C所示码流时，解码器不能够完成实时解码RL6和RL8，因为尽管RL6与RL3的时间间隔超过k秒，但是RL6参考的知识图像有2个与RL3不同；尽管RL8参考的知识图像与RL6参考的知识图像只有1个不同，但是RL8和RL6之间的时间间隔小于k秒：
基于与上述方法相同的发明构思，本发明实施例还提供了一种设备1000，该设备1000包括第一获取模块1001、第二获取模块1002、确定模块1003，其中：
第一获取模块1001，用于从码流中获取第一标识，所述第一标识用于表示所述码流允许的知识图像之间的最小解码时间间隔k；
第二获取模块1002，用于若当前解码图像参考了知识图像进行解码，
解析码流时获取当前解码图像的解码时刻ti与最近一次参考了新的知识图像的第一解码图像的解码时刻tj，其中，所述新的知识图像为解码所述第一解码图像时未被解码或需要重新解码的知识图像；
确定模块1003，用于根据ti与tj的差值与k的大小关系，确定出预设数量个知识图像作为所述当前解码图像的候选参考图像。
需要说明的是，上述第一获取模块1001、第二获取模块1002、确定模块1003可应用于编码端或解码端的帧间预测过程。具体的，在编码端，这些模块可应用于前述 编码器20的预测处理单元260中的帧间预测单元244；在解码端，这些模块可应用于前述解码器30的预测处理单元360中的帧间预测单元344。
还需要说明的是，第一获取模块1001、第二获取模块1002、确定模块1003的具体实现过程可参考上述方法实施例的详细描述，为了说明书的简洁，这里不再赘述。
本领域技术人员能够领会，结合本文公开描述的各种说明性逻辑框、模块和算法步骤所描述的功能可以硬件、软件、固件或其任何组合来实施。如果以软件来实施，那么各种说明性逻辑框、模块、和步骤描述的功能可作为一或多个指令或代码在计算机可读媒体上存储或传输，且由基于硬件的处理单元执行。计算机可读媒体可包含计算机可读存储媒体，其对应于有形媒体，例如数据存储媒体，或包括任何促进将计算机程序从一处传送到另一处的媒体(例如，根据通信协议)的通信媒体。以此方式，计算机可读媒体大体上可对应于(1)非暂时性的有形计算机可读存储媒体，或(2)通信媒体，例如信号或载波。数据存储媒体可为可由一或多个计算机或一或多个处理器存取以检索用于实施本申请中描述的技术的指令、代码和/或数据结构的任何可用媒体。计算机程序产品可包含计算机可读媒体。
作为实例而非限制，此类计算机可读存储媒体可包括RAM、ROM、EEPROM、CD-ROM或其它光盘存储装置、磁盘存储装置或其它磁性存储装置、快闪存储器或可用来存储指令或数据结构的形式的所要程序代码并且可由计算机存取的任何其它媒体。并且，任何连接被恰当地称作计算机可读媒体。举例来说，如果使用同轴缆线、光纤缆线、双绞线、数字订户线(DSL)或例如红外线、无线电和微波等无线技术从网站、服务器或其它远程源传输指令，那么同轴缆线、光纤缆线、双绞线、DSL或例如红外线、无线电和微波等无线技术包含在媒体的定义中。但是，应理解，所述计算机可读存储媒体和数据存储媒体并不包括连接、载波、信号或其它暂时媒体，而是实际上针对于非暂时性有形存储媒体。如本文中所使用，磁盘和光盘包含压缩光盘(CD)、激光光盘、光学光盘、数字多功能光盘(DVD)和蓝光光盘，其中磁盘通常以磁性方式再现数据，而光盘利用激光以光学方式再现数据。以上各项的组合也应包含在计算机可读媒体的范围内。
可通过例如一或多个数字信号处理器(DSP)、通用微处理器、专用集成电路(ASIC)、现场可编程逻辑阵列(FPGA)或其它等效集成或离散逻辑电路等一或多个处理器来执行指令。因此，如本文中所使用的术语“处理器”可指前述结构或适合于实施本文中所描述的技术的任一其它结构中的任一者。另外，在一些方面中，本文中所描述的各种说明性逻辑框、模块、和步骤所描述的功能可以提供于经配置以用于编码和解码的专用硬件和/或软件模块内，或者并入在组合编解码器中。而且，所述技术可完全实施于一或多个电路或逻辑元件中。
本申请的技术可在各种各样的装置或设备中实施，包含无线手持机、集成电路(IC)或一组IC(例如，芯片组)。本申请中描述各种组件、模块或单元是为了强调用于执行所揭示的技术的装置的功能方面，但未必需要由不同硬件单元实现。实际上，如上文所描述，各种单元可结合合适的软件和/或固件组合在编码解码器硬件单元中，或者通过互操作硬件单元(包含如上文所描述的一或多个处理器)来提供。
在上述实施例中，对各个实施例的描述各有侧重，某个实施例中没有详述的部分，可以参见其他实施例的相关描述。
以上所述，仅为本申请示例性的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应该以权利要求的保护范围为准。

Claims (26)

  1. 一种视频解码方法，其特征在于，所述方法包括：
    从码流中获取第一标识，所述第一标识用于表示所述码流允许的知识图像之间的最小解码时间间隔k；
    若当前解码图像参考了知识图像进行解码，
    解析码流时获取当前解码图像的解码时刻t i与最近一次参考了新的知识图像的第一解码图像的解码时刻t j，其中，所述新的知识图像为解码所述第一解码图像时未被解码或需要重新解码的知识图像；
    根据t i与t j的差值与k的大小关系，确定出预设数量个知识图像作为所述当前解码图像的候选参考图像。
  2. 根据权利要求1所述的方法，其特征在于，所述k不小于所述码流符合的profile或level允许的最小解码时间间下限。
  3. 根据权利要求1所述的方法，其特征在于，所述根据t i与t j的差值与k的大小关系，确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
    若t i-t j不小于k，则确定出n个知识图像作为所述当前解码图像的候选参考图像；所述n个知识图像包括当前未解码或需要进行重新解码的知识图像，n为正整数。
  4. 根据权利要求1所述的方法，其特征在于，所述根据t i与t j的差值与k的大小关系，确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
    若t i-t j不小于k，则确定出m+n个知识图像作为所述当前解码图像的候选参考图像；其中，m个知识图像包括已解码的知识图像，n个知识图像包括当前未解码或需要进行重新解码的知识图像，m，n为正整数。
  5. 根据权利要求3所述的方法，其特征在于，所述确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
    在当前未解码或需要重新解码的知识图像中确定出与所述当前解码图像内容相似性最高的n个知识图像。
  6. 根据权利要求3所述的方法，其特征在于，所述确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
    在当前未解码或需要进行重新解码的知识图像中确定出与所述当前解码图像显示时刻最接近n个的知识图像。
  7. 根据权利要求3所述的方法，其特征在于，所述确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
    在当前未解码或需要重新解码的知识图像中确定出n个编码效率最高的知识图像。
  8. 根据权利要求3-7中任一项所述的方法，其特征在于，所述根据t i与t j的差值与k的大小关系，确定出n个知识图像作为所述当前解码图像的候选参考图像包括：
    若t i-t j小于k，则确定出m个知识图像作为所述当前解码图像的候选参考图像； 其中，m个知识图像包括已解码且不需要重新编码的知识图像，m为正整数。
  9. 一种视频解码装置，其特征在于，所述装置包括：
    第一获取模块，用于从码流中获取第一标识，所述第一标识用于表示所述码流允许的知识图像之间的最小解码时间间隔k；
    第二获取模块，用于若当前解码图像参考了知识图像进行解码，
    解析码流时获取当前解码图像的解码时刻t i与最近一次参考了新的知识图像的第一解码图像的解码时刻t j，其中，所述新的知识图像为解码所述第一解码图像时未被解码或需要重新解码的知识图像；
    确定模块，用于根据t i与t j的差值与k的大小关系，确定出预设数量个知识图像作为所述当前解码图像的候选参考图像。
  10. 根据权利要求9所述的装置，其特征在于，所述k不小于所述码流符合的profile或level允许的最小解码时间间下限。
  11. 根据权利要求9所述的装置，其特征在于，所述确定模块具体用于：
    若t i-t j不小于k，则确定出n个知识图像作为所述当前解码图像的候选参考图像；所述n个知识图像包括当前未解码或需要进行重新解码的知识图像，n为正整数。
  12. 根据权利要求9所述的装置，其特征在于，所述确定模块具体用于：
    若t i-t j不小于k，则确定出m+n个知识图像作为所述当前解码图像的候选参考图像；其中，m个知识图像包括已解码的知识图像，n个知识图像包括当前未解码或需要进行重新解码的知识图像，m，n为正整数。
  13. 根据权利要11所述的装置，其特征在于，所述确定模块具体用于：
    在当前未解码或需要重新解码的知识图像中确定出与所述当前解码图像内容相似性最高的n个知识图像。
  14. 根据权利要11所述的装置，其特征在于，所述确定模块具体用于：
    在当前未解码或需要进行重新解码的知识图像中确定出与所述当前解码图像显示时刻最接近n个的知识图像。
  15. 根据权利要11所述的装置，其特征在于，所述确定模块具体用于：
    在当前未解码或需要重新解码的知识图像中确定出n个编码效率最高的知识图像。
  16. 根据权利要11-15所述的装置，其特征在于，所述确定模块具体用于：
    若t i-t j小于k，则确定出m个知识图像作为所述当前解码图像的候选参考图像；其中，m个知识图像包括已解码且不需要重新解码的知识图像，m为正整数。
  17. 一种视频编解码设备，包括：相互耦合的非易失性存储器和处理器，所述处理器调用存储在所述存储器中的程序代码以执行如权利要求1-8任一项所描述的方法。
  18. 一种视频解码方法，其特征在于，所述方法包括：
    获取第一解码图像；所述第一解码图像为主码流中在当前待解码图像之前最近一个紧随序列头后的支持随机访问且仅参考知识图像的图像；
    将新知识图像作为所述当前待解码图像的参考图像；所述当前待解码图像为支持随机访问且仅参考知识图像的图像；
    其中，在所述主码流中，所述当前待解码图像和所述第一解码图像之间解码的图像的数目至少为f*k；所述k为所述主码流允许的知识图像之间的最小解码时间间隔；所述f为所述主码流中声明的视频序列的帧率；所述新知识图像的个数不大于预设值n；所述n为正整数；所述新知识图像为所述当前待解码图像参考的知识图像中没有被所述第一解码图像所参考的知识图像。
  19. 根据权利要18所述的方法，其特征在于，所述方法还包括：
    根据所述新知识图像解码所述当前待解码图像。
  20. 根据权利要18或19所述的方法，其特征在于，n＝1。
  21. 根据权利要18-20任一项所述的方法，其特征在于，所述新知识图像是通过解码知识库码流得到的。
  22. 一种视频解码装置，其特征在于，所述装置包括：
    第二获取模块，用于获取第一解码图像；所述第一解码图像为主码流中在当前待解码图像之前最近一个紧随序列头后的支持随机访问且仅参考知识图像的图像；
    确定模块，用于将新知识图像作为所述当前待解码图像的参考图像；所述当前待解码图像为支持随机访问且仅参考知识图像的图像；
    其中，在所述主码流中，所述当前待解码图像和所述第一解码图像之间解码的图像的数目至少为f*k；所述k为所述主码流允许的知识图像之间的最小解码时间间隔；所述f为所述主码流中声明的视频序列的帧率；所述新知识图像的个数不大于预设值n；所述n为正整数；所述新知识图像为所述当前待解码图像参考的知识图像中没有被所述第一解码图像所参考的知识图像。
  23. 根据权利要求22所述的装置，其特征在于，所述装置还包括解码模块，用于根据所述新知识图像解码所述当前待解码图像。
  24. 根据权利要求22或23所述的装置，其特征在于，n＝1。
  25. 根据权利要求22-24任一项所述的装置，其特征在于，所述新知识图像是通过解码知识库码流得到的。
  26. 一种视频解码设备，包括：相互耦合的非易失性存储器和处理器，所述处理器调用存储在所述存储器中的程序代码以执行如权利要求18-21任一项所描述的方法。
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