CN116527889A

CN116527889A - Image prediction method and device

Info

Publication number: CN116527889A
Application number: CN202310545957.3A
Authority: CN
Inventors: 徐巍炜; 赵寅; 杨海涛
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-09-25
Filing date: 2018-09-25
Publication date: 2023-08-01
Also published as: CN110944171B; CN110944171A

Abstract

The embodiment of the application discloses an image prediction method and a related product. The method comprises the following steps: analyzing the code stream to obtain a multi-hypothesis information index of the current image block to be decoded; according to the multi-hypothesis information index, first multi-hypothesis information corresponding to the current image block is obtained from a multi-hypothesis information list, the first multi-hypothesis information comprises a motion information index and a first identifier, the motion information index of the first multi-hypothesis information indicates multi-hypothesis motion information of the current image block to be decoded, the first identifier indicates a first division mode of a multi-hypothesis method, and the first multi-hypothesis information further comprises parameters of the first division mode; and processing a plurality of hypothetical predicted image blocks by using the first division mode according to the first identifier and the parameters of the first division mode so as to obtain the predicted image block of the current image block to be decoded. Thus, different image blocks can be obtained by using different division modes, so that the image prediction efficiency is improved, and the decoding time is reduced.

Description

Image prediction method and device

Technical Field

The present application relates to the field of video encoding and decoding technologies, and more particularly, to an image prediction method and apparatus.

Background

Digital video capabilities can be incorporated into a wide variety of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (personal digital assistant, PDAs), laptop or desktop computers, tablet computers, electronic book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radio telephones (so-called "smartphones"), video teleconferencing devices, video streaming devices, and the like. Digital video devices implement video compression techniques such as those described 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 coding standard H.265/high efficiency video coding (high efficiency video coding, HEVC) standard, and extensions of such standards. Video devices may more efficiently transmit, receive, encode, decode, and/or store digital video information by implementing such video compression techniques.

Video compression techniques perform spatial (intra-picture) prediction and/or temporal (inter-picture) prediction to reduce or eliminate redundancy inherent in video sequences. For block-based video coding, a video slice (i.e., a video frame or a portion of a video frame) may be divided into tiles, which may also be referred to as treeblocks, coding Units (CUs), and/or coding nodes. Image blocks in a slice to be intra-coded (I) of an image are encoded using spatial prediction with respect to reference samples in neighboring blocks in the same image. Image blocks in a to-be-inter-coded (P or B) stripe of an image may use spatial prediction with respect to reference samples in neighboring blocks in the same image or temporal prediction with respect to reference samples in other reference images. An image may be referred to as a frame and a reference image may be referred to as a reference frame.

Among them, various video coding standards including HEVC standard propose predictive coding modes for image blocks, i.e. predicting a block currently to be coded based on an already coded video data block. In intra prediction mode, a current block is predicted based on one or more previously decoded neighboring blocks in the same image as the current block; in the inter prediction mode, a current block is predicted based on already decoded blocks in different pictures.

The existing method in the inter prediction mode has low prediction efficiency, thereby affecting the execution time of the whole decoding process.

Disclosure of Invention

The application provides an image prediction method and device, which can improve the efficiency of image prediction and further reduce the time of the whole decoding process.

In a first aspect, there is provided an image prediction method, the method comprising: analyzing the code stream to obtain a multi-hypothesis information index of the current image block to be decoded; obtaining first multi-hypothesis information corresponding to the current image block from a multi-hypothesis information list according to the multi-hypothesis information index, wherein the first multi-hypothesis information comprises a motion information index and a first identifier, the motion information index of the first multi-hypothesis information indicates multi-hypothesis motion information of the current image block to be decoded, the first identifier indicates a first division mode of a multi-hypothesis method, and the first multi-hypothesis information further comprises parameters of the first division mode; performing motion compensation according to the motion information of the multi-hypothesis coding of the current image block to be decoded to obtain a plurality of hypothesized predicted image blocks; and processing the plurality of hypothetical predicted image blocks by using the first division mode according to the first identifier and the parameters of the first division mode to obtain the predicted image block of the current image block to be decoded.

In a possible implementation manner, the multi-hypothesis information list includes at least one piece of the first multi-hypothesis information, and at least one piece of second multi-hypothesis information, where the second multi-hypothesis information includes a motion information index and a second identifier, where the motion information index of the second multi-hypothesis information indicates multi-hypothesis motion information of an image block, and the second identifier indicates a second division manner of the multi-hypothesis method, and the second multi-hypothesis information further includes parameters of the second division manner.

In one possible implementation, the first identifier and the second identifier are different values of the same flag bit.

In one possible implementation manner, the first division manner is triangle division, the parameter of the first division manner indicates a division direction of the triangle division, the second division manner is square division, and the parameter of the second division manner indicates a weighting coefficient of the square division.

It should be appreciated that the first and second division are different division schemes, each for dividing the predicted image blocks of multiple hypotheses, i.e., for dividing the predicted image blocks of the original hypothesis and the predicted image blocks of additional hypotheses. Regarding the specific methods and modes of dividing the prediction image block by the multiple hypothesis method, reference may be made to the contents of the jfet-K0144 proposal (triangle division) and the jfet-K0257 proposal (square division).

In one possible implementation manner, the first division manner is a triangle division, a parameter of the first division manner indicates a division direction of the triangle division, or the first division manner is a square division, and a parameter of the first division manner indicates a weighting coefficient of the square division.

In one possible implementation manner, the method further includes: and acquiring multi-hypothesis motion information of the current image block to be decoded from a candidate motion information list of the current image block to be decoded according to the motion information index of the first multi-hypothesis information, wherein the multi-hypothesis motion information of the current image block to be decoded comprises motion information of an original hypothesis and motion information of an additional hypothesis.

In a possible implementation manner, the motion information index of the first multi-hypothesis information includes a first index and a second index, the multi-hypothesis motion information of the current image block to be decoded is obtained from a candidate motion information list of the current image block to be decoded according to the motion information index of the first multi-hypothesis information, including: according to the first index, the motion information of the original hypothesis is obtained from a first candidate motion information list of the current image block, and according to the second index, the motion information of the additional hypothesis is obtained from a second candidate motion information list of the current image block.

In this way, with the above method, since the code stream carries the division identifier indicating the multi-hypothesis method, the decoding end can determine which division mode is used to predict the image in the multi-hypothesis method, that is, for different image blocks, different division modes can be used to obtain the prediction block of the image block, so that the image block can use the division mode more suitable for the characteristics of the image block, thereby improving the efficiency of image prediction and reducing the decoding time.

In a second aspect, an image prediction apparatus is provided, the apparatus comprising means for performing the method in any of the implementations of the first aspect described above.

In a third aspect, there is provided an image prediction apparatus comprising: a non-volatile memory and a processor coupled to each other, the processor invoking program code stored in the memory to perform some or all of the steps of the method in any of the implementations of the first aspect.

In a fourth aspect, a computer readable storage medium is provided, the computer readable storage medium storing program code, wherein the program code comprises instructions for performing part or all of the steps of the method in any one of the implementations of the first aspect.

In a fifth aspect, there is provided a computer program product, which when run on a computer, causes the computer to perform some or all of the steps of the method in any one of the implementations of the first aspect.

In a sixth aspect, there is provided an image prediction apparatus comprising: a memory for storing video data in the form of a code stream, the video data comprising one or more image blocks; the video decoder is used for analyzing the code stream to obtain a multi-hypothesis information index of the current image block to be decoded; obtaining first multi-hypothesis information corresponding to the current image block from a multi-hypothesis information list according to the multi-hypothesis information index, wherein the first multi-hypothesis information comprises a motion information index and a first identifier, the motion information index of the first multi-hypothesis information indicates multi-hypothesis motion information of the current image block to be decoded, the first identifier indicates a first division mode of a multi-hypothesis method, and the first multi-hypothesis information further comprises parameters of the first division mode; performing motion compensation according to the motion information of the multi-hypothesis coding of the current image block to be decoded to obtain a plurality of hypothesized predicted image blocks; and processing the plurality of hypothetical predicted image blocks by using the first division mode according to the first identifier and the parameters of the first division mode to obtain the predicted image block of the current image block to be decoded.

In a possible implementation, the video decoder is further configured to: and acquiring multi-hypothesis motion information of the current image block to be decoded from a candidate motion information list of the current image block to be decoded according to the motion information index of the first multi-hypothesis information, wherein the multi-hypothesis motion information of the current image block to be decoded comprises motion information of an original hypothesis and motion information of an additional hypothesis.

In a possible implementation manner, the motion information index of the first multi-hypothesis information includes a first index and a second index, and in the aspect of obtaining multi-hypothesis motion information of the current image block to be decoded from the candidate motion information list of the current image block to be decoded according to the motion information index of the first multi-hypothesis information, the video decoder is further configured to: according to the first index, the motion information of the original hypothesis is obtained from a first candidate motion information list of the current image block, and according to the second index, the motion information of the additional hypothesis is obtained from a second candidate motion information list of the current image block.

Therefore, with the adoption of the device, as the code stream carries the division mark indicating the multi-hypothesis method, the decoding end can determine which division mode is used for predicting the image in the multi-hypothesis method, namely, for different image blocks, different division modes can be used for obtaining the prediction block of the image block, so that the image block can use the division mode which is more suitable for the characteristics of the image block, the image prediction efficiency is improved, and the decoding time is reduced.

Drawings

FIG. 1 is a conceptual block diagram of an encoding system 10;

FIG. 2 is a schematic block diagram of an example of video encoder 20;

fig. 3 is a schematic block diagram of an example of video decoder 30;

fig. 4 is an illustration of an example of video encoding system 40;

FIG. 5 is a schematic diagram of an apparatus 500 for implementing the method of the present application;

FIG. 6 is a schematic diagram of an image prediction method;

fig. 7 is a schematic diagram of an image prediction apparatus.

Detailed Description

The technical solutions in the present application will be described below with reference to the accompanying drawings.

Hereinafter, embodiments of the present invention and application examples using the embodiments of the present invention will be described with reference to the accompanying drawings. Video coding generally refers to processing a sequence of pictures that form a video or video sequence. In the field of video coding, the terms "picture", "frame" or "image" may be used as synonyms. Video encoding as used in this application (or this disclosure) refers to video encoding or video decoding. Video encoding is performed on the source side, typically including processing (e.g., by compression) the original video picture to reduce the amount of data needed to represent the video picture (and thus more efficiently store and/or transmit). Video decoding is performed on the destination side, typically involving inverse processing with respect to the encoder to reconstruct the video pictures. The embodiment relates to video pictures (or collectively pictures, as will be explained below) 'encoding' is understood to relate to 'encoding' or 'decoding' of a video sequence. The combination of the encoding portion and the decoding portion is also called codec (encoding and decoding).

In the case of lossless video coding, the original video picture may be reconstructed, i.e., 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). In the case of lossy video coding, the amount of data needed to represent a video picture is reduced by performing further compression, e.g. quantization, whereas the decoder side cannot reconstruct the video picture completely, i.e. the quality of the reconstructed video picture is lower or worse than the quality of the original video picture.

Several video coding standards of h.261 belong to the "lossy hybrid video codec" (i.e. spatial and temporal prediction in the sample domain is combined with 2D transform coding in the transform domain for applying quantization). Each picture of a video sequence is typically partitioned into non-overlapping sets of blocks, typically encoded at the block level. In other words, the encoder side typically processes, i.e. encodes, video at the block (video block) level, e.g. generates a prediction block by spatial (intra-picture) prediction and temporal (inter-picture) prediction, subtracts the prediction block from the current block (currently processed or to-be-processed block) to obtain a residual block, transforms the residual block in the transform domain and quantizes the residual block to reduce the amount of data to be transmitted (compressed), while the decoder side applies the inverse processing part of the relative encoder to the encoded or compressed block to reconstruct the current block for representation. In addition, the encoder replicates the decoder processing loop so that the encoder and decoder generate the same predictions (e.g., intra-prediction and inter-prediction) and/or reconstructions for processing, i.e., encoding, the subsequent blocks.

As used herein, the term "block" may be a portion of a picture or frame. For ease of description, embodiments of the present invention are described with reference to High-Efficiency Video Coding, HEVC developed by the video coding joint working group (Joint Collaboration Team on Video Coding, JCT-VC) of the ITU-T video coding experts group (Video Coding Experts Group, VCEG) and the ISO/IEC moving Picture experts group (Motion Picture Experts Group, MPEG). Those of ordinary skill in the art understand that embodiments of the present invention are not limited to HEVC. May refer to a CU, PU, and TU. In HEVC, a CTU is split into multiple CUs by using a quadtree structure denoted as a coding tree. A decision is made at the CU level whether to encode a picture region using inter-picture (temporal) or intra-picture (spatial) prediction. Each CU may be further split into one, two, or four PUs depending on the PU split type. The same prediction process is applied within one PU and the relevant information is transmitted to the decoder on a PU basis. After the residual block is obtained by applying the prediction process based on the PU split type, the CU may be partitioned into Transform Units (TUs) according to other quadtree structures similar to the coding tree for the CU. In a recent development of video compression technology, a Quad tree and a binary tree (qd-tree and binary tree, QTBT) partition frames are used to partition the encoded blocks. In QTBT block structures, a CU may be square or rectangular in shape. In XXX, coding Tree Units (CTUs) are first partitioned by a quadtree structure. The quadtree leaf nodes are further partitioned by a binary tree structure. Binary leaf nodes are called Coding Units (CUs), and the segments are used for prediction and transformation processing without any other segmentation. This means that the block sizes of the CU, PU and TU are the same in the QTBT encoded block structure. Also, the use of multiple partitions, such as a trigeminal tree partition, with QTBT block structures is proposed.

Embodiments of the encoder 20, decoder 30 and codec systems 10, 40 are described below based on fig. 1-4 (before embodiments of the present invention are described in more detail based on fig. 6).

Fig. 1 is a conceptual or schematic block diagram illustrating an exemplary encoding system 10, e.g., a video encoding system 10 that may utilize the techniques of this application (this disclosure). Encoder 20 (e.g., video encoder 20) and decoder 30 (e.g., video decoder 30) of video encoding system 10 represent examples of equipment that may be used to perform techniques for image prediction according to various examples described herein. As shown in fig. 1, encoding system 10 includes a source device 12 for providing encoded data 13, e.g., encoded pictures 13, to a destination device 14, e.g., decoding encoded data 13.

Source device 12 includes an encoder 20 and, in addition, or alternatively, may include a picture source 16, a preprocessing unit 18, such as picture preprocessing unit 18, and a communication interface or communication unit 22.

The picture source 16 may include or may be any type of picture capture device for capturing, for example, real world pictures, and/or any type of picture or comment (for screen content encoding, some text on the screen is also considered part of the picture or image to be encoded), for example, a computer graphics processor for generating computer animated pictures, or any type of device for capturing and/or providing real world pictures, computer animated pictures (e.g., screen content, virtual Reality (VR) pictures), and/or any combination thereof (e.g., real scene (augmented reality, AR) pictures).

A (digital) picture is or can be regarded as a two-dimensional array or matrix of sampling points with luminance values. The sampling points in the array may also be referred to as pixels (pixels) or pixels (pels). The number of sampling points of the array or picture in the horizontal and vertical directions (or axes) defines the size and/or resolution of the picture. To represent color, three color components are typically employed, i.e., a picture may be represented as or contain three sample arrays. In RBG format or color space, a picture includes corresponding red, green, and blue sample arrays. However, in video coding, each pixel is typically represented in a luminance/chrominance format or color space, e.g., YCbCr, including a luminance component indicated by Y (which may sometimes be indicated by L) and two chrominance components indicated by Cb and Cr. The luminance (luma) component Y represents the luminance or grayscale intensity (e.g., the same in a grayscale picture), while the two chrominance (chroma) components Cb and Cr represent the chrominance or color information components. Accordingly, a picture in YCbCr format includes a luma sample array of luma sample values (Y) and two chroma sample arrays of chroma values (Cb and Cr). Pictures in RGB format may be converted or transformed into YCbCr format and vice versa, a process also known as color transformation or conversion. If the picture is black and white, the picture may include only an array of luma samples.

Picture source 16 (e.g., video source 16) may be, for example, a camera for capturing pictures, a memory such as a picture memory, a memory that includes or stores previously captured or generated pictures, and/or any type of (internal or external) interface that captures or receives pictures. The camera may be, for example, an integrated camera, either local or integrated in the source device, and the memory may be, for example, an integrated memory, either local or integrated in the source device. The interface may be, for example, an external interface that receives pictures from an external video source, such as an external picture capture device, like a camera, an external memory or an external picture generation device, such as an external computer graphics processor, a computer or a server. The interface may be any kind of interface according to any proprietary or standardized interface protocol, e.g. a wired or wireless interface, an optical interface. The interface to acquire the picture data 17 may be the same interface as the communication interface 22 or a part of the communication interface 22.

The picture or picture data 17 (e.g., video data 16) may also be referred to as an original picture or original picture data 17, as distinguished from the preprocessing unit 18 and the processing performed by the preprocessing unit 18.

The preprocessing unit 18 is for receiving (original) picture data 17 and performing preprocessing on the picture data 17 to obtain a preprocessed picture 19 or preprocessed picture data 19. For example, preprocessing performed by preprocessing unit 18 may include truing, color format conversion (e.g., from RGB to YCbCr), toning, or denoising. It is understood that the preprocessing unit 18 may be an optional component.

Encoder 20, e.g., video encoder 20, is operative to receive preprocessed picture data 19 and provide encoded picture data 21 (details are described further below, e.g., based on fig. 2 or fig. 4). In one example, the encoder 20 may be configured to carry, during encoding, an identifier indicating a partition mode of the multi-hypothesis method and a parameter of the partition mode in a code stream of the image block, for reference to corresponding paragraphs hereinafter.

The communication interface 22 of the source device 12 may be used to receive the encoded picture data 21 and transmit it to other devices, such as the destination device 14 or any other device, for storage or direct reconstruction, or for processing the encoded picture data 21 before storing the encoded data 13 and/or transmitting the encoded data 13 to the other devices, such as the destination device 14 or any other device for decoding or storage, respectively.

The destination device 14 includes a decoder 30 (e.g., a video decoder 30), and may additionally, i.e., alternatively, include a communication interface or unit 28, a post-processing unit 32, and a display device 34.

The communication interface 28 of the destination device 14 is for receiving the encoded picture data 21 or the encoded data 13, e.g. directly from the source device 12 or any other source, e.g. a storage device, e.g. an encoded picture data storage device.

Communication interface 22 and communication interface 28 may be used to transmit or receive encoded picture data 21 or encoded data 13 via a direct communication link between source device 12 and destination device 14, such as a direct wired or wireless connection, or via any type of network, such as a wired or wireless network or any combination thereof, or any type of private and public networks, or any combination thereof.

The communication interface 22 may, for example, be used to encapsulate the encoded picture data 21 into a suitable format, such as packets, for transmission over a communication link or communication network.

The communication interface 28 forming a corresponding part of the communication interface 22 may for example be used for unpacking the encoded data 13 to obtain the encoded picture data 21.

Both communication interface 22 and communication interface 28 may be configured as unidirectional communication interfaces, as indicated by the arrow from source device 12 to destination device 14 for encoded picture data 13 in fig. 1, or as bi-directional communication interfaces, and may be used, for example, to send and receive messages to establish connections, acknowledge and exchange any other information related to the communication link and/or data transmission, such as encoded picture data transmission.

Decoder 30 is used to receive encoded picture data 21 and provide decoded picture data 31 or decoded picture 31 (details will be described further below, e.g., based on fig. 3 or fig. 5). In one example, decoder 30 may be used to implement the image prediction methods described herein.

The post-processor 32 of the destination device 14 is used to post-process the decoded picture data 31 (also referred to as reconstructed slice data), e.g., the decoded picture 131, to obtain post-processed picture data 33, e.g., the post-processed picture 33. Post-processing performed by post-processing unit 32 may include, for example, color format conversion (e.g., conversion from YCbCr to RGB), toning, truing, or resampling, or any other processing for preparing decoded picture data 31 for display by display device 34, for example.

The display device 34 of the destination device 14 is for receiving the post-processed picture data 33 to display the picture to, for example, a user or viewer. The display device 34 may be or include any type of display for presenting reconstructed pictures, for example, an integrated or external display or monitor. For example, the display may include a liquid crystal display (liquid crystal display, LCD), an organic light emitting diode (organic light emitting diode, OLED) display, a plasma display, a projector, a micro LED display, a liquid crystal on silicon (liquid crystal on silicon, LCoS), a digital light processor (digital light processor, DLP), or any other type of display.

Although fig. 1 depicts source device 12 and destination device 14 as separate devices, device embodiments may also include the functionality of both source device 12 and destination device 14, or both, i.e., source device 12 or corresponding functionality and destination device 14 or corresponding functionality. In such embodiments, the source device 12 or corresponding functionality and the destination device 14 or corresponding functionality may be implemented using the same hardware and/or software, or using separate hardware and/or software, or any combination thereof.

It will be apparent to those skilled in the art from this description that the functionality of the different units or the presence and (exact) division of the functionality of the source device 12 and/or destination device 14 shown in fig. 1 may vary depending on the actual device and application.

Encoder 20 (e.g., video encoder 20) and decoder 30 (e.g., video decoder 30) may each be implemented as any of a variety of suitable circuits, such as one or more microprocessors, digital signal processors (digital signal processor, DSPs), application-specific integrated circuits (ASICs), field-programmable gate array, FPGA, discrete logic, hardware, or any combinations thereof. If the techniques are implemented in part in software, an apparatus may store instructions of the software in a suitable non-transitory computer-readable storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Any of the foregoing (including hardware, software, a combination of hardware and software, etc.) may be considered one or more processors. Each of video encoder 20 and video decoder 30 may be contained in one or more encoders or decoders, either of which may be integrated as part of a combined encoder/decoder (codec) in the corresponding device.

Source device 12 may be referred to as a video encoding device or video encoding apparatus. Destination device 14 may be referred to as a video decoding device or video decoding apparatus. The source device 12 and the destination device 14 may be examples of video encoding devices or video encoding apparatus.

Source device 12 and destination device 14 may comprise any of a variety of devices, including any type of handheld or stationary device, such as a notebook or laptop computer, mobile phone, smart phone, tablet or tablet computer, video camera, desktop computer, set-top box, television, display device, digital media player, video game console, video streaming device (e.g., content service server or content distribution server), broadcast receiver device, broadcast transmitter device, etc., and may not use or use any type of operating system.

In some cases, source device 12 and destination device 14 may be equipped for wireless communication. Thus, the source device 12 and the destination device 14 may be wireless communication devices.

In some cases, the video encoding system 10 shown in fig. 1 is merely an example, and the techniques of this disclosure may be applicable to video encoding settings (e.g., video encoding or video decoding) that do not necessarily involve any data communication between encoding and decoding devices. In other examples, the data may be retrieved from local memory, streamed over a network, and the like. The video encoding device may encode and store data to the memory and/or the video decoding device may retrieve and decode data from the memory. In some examples, encoding and decoding are performed by devices that do not communicate with each other, but instead only encode data to memory and/or retrieve data from memory and decode data.

It should be appreciated that for each of the examples described above with reference to video encoder 20, video decoder 30 may be used to perform the reverse process. Regarding signaling syntax elements, video decoder 30 may be configured to receive and parse such syntax elements and decode the associated video data accordingly. In some examples, video encoder 20 may entropy encode one or more syntax elements defining … … into an encoded video bitstream. In such examples, video decoder 30 may parse such syntax elements and decode the relevant video data accordingly.

Encoder & encoding method

Fig. 2 shows a schematic block diagram of an example of a video encoder 20 for implementing the techniques of this application (disclosure). In the example of fig. 2, video encoder 20 includes residual calculation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, buffer 216, loop filter unit 220, decoded picture buffer (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 video encoder 20 shown in fig. 2 may also be referred to as a hybrid video encoder or a video encoder according to a hybrid video codec.

For example, 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 a forward signal path of the encoder 20, whereas for example the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the decoded picture buffer (decoded picture buffer, DPB) 230, the prediction processing unit 260 form a backward signal path of the encoder, wherein the backward signal path of the encoder corresponds to the signal path of the decoder (see decoder 30 in fig. 3).

Encoder 20 receives picture 201 or a block 203 of picture 201, e.g., a picture in a sequence of pictures forming a video or video sequence, through, e.g., input 202. The picture block 203 may also be referred to as a current picture block or a picture block to be encoded, and the picture 201 may be referred to as a current picture or a picture to be encoded (especially when distinguishing the current picture from other pictures in video encoding, such as previously encoded and/or decoded pictures in the same video sequence, i.e. a video sequence also comprising the current picture).

Segmentation

An embodiment of encoder 20 may comprise a partitioning unit (not shown in fig. 2) for partitioning picture 201 into a plurality of blocks, e.g. blocks 203, typically into a plurality of non-overlapping blocks. The segmentation unit may be used to use the same block size for all pictures in the video sequence and a corresponding grid defining the block size, or to alter the block size between pictures or subsets or groups of pictures and to segment each picture into corresponding blocks.

In one example, prediction processing unit 260 of video encoder 20 may be configured to perform any combination of the above-described partitioning techniques.

Like picture 201, block 203 is also or may be regarded as a two-dimensional array or matrix of sampling points with luminance values (sampling values), albeit of smaller size than picture 201. In other words, block 203 may include, for example, one sampling array (e.g., a luminance array in the case of black-and-white picture 201) or three sampling arrays (e.g., one luminance array and two chrominance arrays in the case of color pictures) or any other number and/or class of arrays depending on the color format applied. The number of sampling points in the horizontal and vertical directions (or axes) of the block 203 defines the size of the block 203.

The encoder 20 as shown in fig. 2 is used to encode a picture 201 block by block, e.g. perform encoding and prediction on each block 203.

Residual calculation

The residual calculation unit 204 is configured to calculate a residual block 205 based on the picture block 203 and the prediction block 265 (further details of the prediction block 265 are provided below), for example, by subtracting sample values of the prediction block 265 from sample values of the picture block 203 on a sample-by-sample (pixel-by-pixel) basis to obtain the residual block 205 in a sample domain.

Transformation

The transform processing unit 206 is configured to apply a transform, such as a discrete cosine transform (discrete cosine transform, DCT) or a discrete sine transform (discrete sine transform, DST), on the sample values of the residual block 205 to obtain transform coefficients 207 in the transform domain. The transform coefficients 207 may also be referred to as transform residual coefficients and represent the 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 transforms specified for HEVC/H.265. Such integer approximations are typically scaled by some factor compared to the orthogonal DCT transform. To maintain the norms of the forward and inverse transformed processed residual blocks, an additional scaling factor is applied as part of the transformation process. The scaling factor is typically selected based on certain constraints, e.g., the scaling factor is a tradeoff between power of 2, bit depth of transform coefficients, accuracy, and implementation cost for shift operations, etc. For example, a specific scaling factor is specified for inverse transformation by, for example, the inverse transformation processing unit 212 on the decoder 30 side (and for corresponding inverse transformation by, for example, the inverse transformation processing unit 212 on the encoder 20 side), and accordingly, a corresponding scaling factor may be specified for positive transformation by the transformation processing unit 206 on the encoder 20 side.

Quantization

The quantization unit 208 is for quantizing the transform coefficients 207, for example by applying scalar quantization or vector quantization, to obtain quantized transform coefficients 209. The quantized transform coefficients 209 may also be referred to as quantized residual coefficients 209. The quantization process may reduce the bit depth associated with some or all of the transform coefficients 207. For example, n-bit transform coefficients may be rounded down to m-bit transform coefficients during quantization, where n is greater than m. The quantization level may be modified by adjusting quantization parameters (quantization parameter, QP). For example, for scalar quantization, different scales may be applied to achieve finer or coarser quantization. Smaller quantization step sizes correspond to finer quantization, while larger quantization step sizes correspond to coarser quantization. The appropriate quantization step size may be indicated by a quantization parameter (quantization parameter, QP). For example, the quantization parameter may be an index of a predefined set of suitable quantization steps. For example, smaller quantization parameters may correspond to fine quantization (smaller quantization step size) and larger quantization parameters may correspond to coarse quantization (larger quantization step size) and vice versa. Quantization may involve division by a quantization step size and corresponding quantization or inverse quantization, e.g., performed by inverse quantization 210, or may involve multiplication by a quantization step size. Embodiments according to some standards, such as HEVC, may use quantization parameters to determine quantization step sizes. In general, the quantization step size may be calculated based on quantization parameters using a fixed-point approximation of an equation that includes division. Additional scaling factors may be introduced for quantization and inverse quantization to recover norms of residual blocks that may be modified due to the scale used in the fixed point approximation of the equation for quantization step size and quantization parameters. In one example embodiment, the inverse transformed and inverse quantized scales may be combined. Alternatively, a custom quantization table may be used and signaled from the encoder to the decoder, e.g., in a bitstream. Quantization is a lossy operation, where the larger the quantization step size, the larger the loss.

The inverse quantization unit 210 is configured to apply inverse quantization of the quantization unit 208 on the quantized coefficients to obtain inverse quantized coefficients 211, e.g., apply an inverse quantization scheme of the quantization scheme applied by the quantization unit 208 based on or using the same quantization step size as the quantization unit 208. The dequantized coefficients 211 may also be referred to as dequantized residual coefficients 211, correspond to the transform coefficients 207, although the losses due to quantization are typically different from the transform coefficients.

The inverse transform processing unit 212 is configured to apply an inverse transform of the transform applied by the transform processing unit 206, for example, an inverse discrete cosine transform (discrete cosine transform, DCT) or an inverse discrete sine transform (discrete sine transform, DST), to obtain an inverse transform block 213 in the sample domain. The inverse transform block 213 may also be referred to as an inverse transformed inverse quantized block 213 or an inverse transformed residual block 213.

A reconstruction unit 214 (e.g., a summer 214) is used to add the inverse transform block 213 (i.e., the reconstructed residual block 213) to the prediction block 265 to obtain the reconstructed block 215 in the sample domain, e.g., to add sample values of the reconstructed residual block 213 to sample values of the prediction block 265.

Optionally, a buffer unit 216, e.g. a line buffer 216 (or simply "buffer" 216), is used to buffer or store the reconstructed block 215 and the corresponding sample values for e.g. intra prediction. In other embodiments, the encoder may be configured to use the unfiltered reconstructed block and/or the corresponding sample values stored in the buffer unit 216 for any kind of estimation and/or prediction, such as intra prediction.

For example, embodiments of encoder 20 may be configured such that buffer unit 216 is used not only to store reconstructed blocks 215 for intra prediction 254, but also for loop filter unit 220 (not shown in fig. 2), and/or such that buffer unit 216 and decoded picture buffer unit 230 form one buffer, for example. Other embodiments may be used to use the filtered block 221 and/or blocks or samples (neither shown in fig. 2) from the decoded picture buffer 230 as an input or basis for the intra prediction 254.

The loop filter unit 220 (or simply "loop filter" 220) is used to filter the reconstructed block 215 to obtain a filtered block 221, which facilitates pixel transitions or improves video quality. 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, adaptive loop filters (adaptive loop filter, ALF), or sharpening or smoothing filters, or collaborative filters. Although loop filter unit 220 is shown in fig. 2 as an in-loop filter, in other configurations loop filter unit 220 may be implemented as a post-loop filter. The filtered block 221 may also be referred to as a filtered reconstructed block 221. Decoded picture buffer 230 may store the reconstructed encoded block after loop filter unit 220 performs a filtering operation on the reconstructed encoded block.

Embodiments of encoder 20 (and correspondingly loop filter unit 220) may be configured to output loop filter parameters (e.g., sample adaptive offset information), e.g., directly or after entropy encoding by entropy encoding unit 270 or any other entropy encoding unit, e.g., such that decoder 30 may receive and apply the same loop filter parameters for decoding.

Decoded picture buffer (decoded picture buffer, DPB) 230 may be a reference picture memory that stores reference picture data for use by video encoder 20 in encoding video data. DPB 230 may be formed of any of a variety of memory devices, such as dynamic random access memory (dynamic random access memory, DRAM) (including Synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM)), or other types of memory devices. DPB 230 and buffer 216 may be provided by the same memory device or separate memory devices. In a certain example, a decoded picture buffer (decoded picture buffer, DPB) 230 is used to store the filtered block 221. The decoded picture buffer 230 may further be used to store the same current picture or other previously filtered blocks, e.g., previously reconstructed and filtered blocks 221, of different pictures, e.g., previously reconstructed pictures, and may provide complete previously reconstructed, i.e., decoded pictures (and corresponding reference blocks and samples) and/or partially reconstructed current pictures (and corresponding reference blocks and samples), e.g., for inter prediction. In a certain example, if the reconstructed block 215 is reconstructed without in-loop filtering, the decoded picture buffer (decoded picture buffer, DPB) 230 is used to store the reconstructed block 215.

The prediction processing unit 260, also referred to as block prediction processing unit 260, is adapted to receive or obtain block 203 (current block 203 of current picture 201) and reconstructed slice data, e.g. reference samples of the same (current) picture from buffer 216 and/or reference picture data 231 of one or more previously decoded pictures from decoded picture buffer 230, and to process such data for prediction, i.e. to provide a prediction block 265 which may be an inter prediction block 245 or an intra prediction block 255.

The mode selection unit 262 may be used to select a prediction mode (e.g., intra or inter prediction mode) and/or a corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.

Embodiments of mode selection unit 262 may be used to select the prediction mode (e.g., from those supported by prediction processing unit 260) that provides the best match or minimum residual (minimum residual meaning better compression in transmission or storage), or that provides the minimum signaling overhead (minimum signaling overhead meaning better compression in transmission or storage), or both. The mode selection unit 262 may be adapted to determine a prediction mode based on a rate-distortion optimization (rate distortion optimization, RDO), i.e. to select the prediction mode that provides the least rate-distortion optimization, or to select a prediction mode for which the associated rate-distortion at least meets a prediction mode selection criterion.

The prediction processing performed by an instance of encoder 20 (e.g., by prediction processing unit 260) and the mode selection performed (e.g., by mode selection unit 262) will be explained in detail below.

As described above, the encoder 20 is configured to determine or select the best or optimal prediction mode from a (predetermined) set of prediction modes. The set of prediction modes may include, for example, intra prediction modes and/or inter prediction modes.

The set of intra prediction modes may include 35 different intra prediction modes, for example, a non-directional mode such as a DC (or mean) mode and a planar mode, or a directional mode as defined in h.265, or 67 different intra prediction modes, for example, a non-directional mode such as a DC (or mean) mode and a planar mode, or a directional mode as defined in h.266 under development.

The set of (possible) inter prediction modes depends on the available reference pictures (i.e. at least part of the decoded pictures stored in the DBP 230 as described before) and other inter prediction parameters, e.g. on whether the entire reference picture is used or only a part of the reference picture is used, e.g. a search window area surrounding the area of the current block, to search for the best matching reference block, and/or on whether pixel interpolation like half-pixel and/or quarter-pixel interpolation is applied, e.g. on whether or not.

In addition to the above prediction modes, a skip mode and/or a direct mode may also be applied.

The prediction processing unit 260 may be further operative to partition the block 203 into smaller block partitions or sub-blocks, for example, by iteratively using a quad-tree (QT) partition, a binary-tree (BT) partition, or a ternary-tree (TT) partition, or any combination thereof, and to perform prediction for each of the block partitions or sub-blocks, for example, wherein the mode selection includes selecting a tree structure of the partitioned block 203 and selecting a prediction mode applied to each of the block partitions or sub-blocks.

The inter prediction unit 244 may include a motion estimation (motion estimation, ME) unit (not shown in fig. 2) and a motion compensation (motion compensation, MC) unit (not shown in fig. 2). The motion estimation unit is used to receive or obtain a picture block 203 (current picture block 203 of the current picture 201) and a decoded picture 231, or at least one or more previously reconstructed blocks, e.g. reconstructed blocks of one or more other/different previously decoded pictures 231, for motion estimation. For example, the video sequence may include a current picture and a 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.

For example, encoder 20 may be configured to select a reference block from a plurality of reference blocks of the same or different pictures of a plurality of other pictures, and provide the reference picture (or reference picture index … …) and/or an offset (spatial offset) between a position (X, Y coordinates) of the reference block and a position of a current block to a motion estimation unit (not shown in fig. 2) as an inter prediction parameter. This offset is also called Motion Vector (MV).

The motion compensation unit is used to obtain, for example, receive inter prediction parameters and perform inter prediction based on or using the inter prediction parameters to obtain the inter prediction block 245. The motion compensation performed by the motion compensation unit (not shown in fig. 2) may involve fetching or generating a prediction block based on motion/block vectors determined by motion estimation (possibly performing interpolation of sub-pixel accuracy). Interpolation filtering may generate additional pixel samples from known pixel samples, potentially increasing the number of candidate prediction blocks available for encoding a picture block. Upon receiving the motion vector for the PU of the current picture block, motion compensation unit 246 may locate the prediction block to which the motion vector points in a reference picture list. Motion compensation unit 246 may also generate syntax elements associated with the blocks and video slices for use by video decoder 30 in decoding the picture blocks of the video slices.

The intra prediction unit 254 is used to obtain, for example, a picture block 203 (current picture block) that receives the same picture and one or more previously reconstructed blocks, for example, reconstructed neighboring blocks, for intra estimation. For example, encoder 20 may be configured to select an intra-prediction mode from a plurality of (predetermined) intra-prediction modes.

Embodiments of encoder 20 may be used to select an intra-prediction mode based on optimization criteria, such as based on a minimum residual (e.g., the intra-prediction mode that provides a prediction block 255 most similar to current picture block 203) or minimum rate distortion.

The intra prediction unit 254 is further adapted to determine an intra prediction block 255 based on intra prediction parameters like the selected intra prediction mode. In any case, after the intra-prediction mode for the block is selected, the intra-prediction unit 254 is also configured to provide the intra-prediction parameters, i.e., information indicating the selected intra-prediction mode for the block, to the entropy encoding unit 270. In one example, intra-prediction unit 254 may be used to perform any combination of the intra-prediction techniques described below.

The entropy encoding unit 270 is configured to apply an entropy encoding algorithm or scheme (e.g., a variable length coding (variable length coding, VLC) scheme, a Context Adaptive VLC (CAVLC) scheme, an arithmetic coding scheme, a context adaptive binary arithmetic coding (context adaptive binary arithmetic coding, CABAC), a syntax-based context-based binary arithmetic coding (SBAC), a probability interval partitioning entropy (probability interval partitioning entropy, PIPE) coding, or other entropy encoding methods or techniques) to one or all of the quantized residual coefficients 209, inter-prediction parameters, intra-prediction parameters, and/or loop filter parameters (or not) to obtain encoded picture data 21 that may be output by the output 272 in the form of, for example, an encoded bitstream 21. The encoded bitstream may be transmitted to video decoder 30 or archived for later transmission or retrieval by video decoder 30. Entropy encoding unit 270 may also be used to entropy encode other syntax elements of the current video slice being encoded.

Other structural variations of video encoder 20 may be used to encode the video stream. For example, the non-transform based encoder 20 may directly quantize the residual signal without a transform processing unit 206 for certain blocks or frames. In another embodiment, encoder 20 may have quantization unit 208 and inverse quantization unit 210 combined into a single unit.

Fig. 3 shows an exemplary video decoder 30 for implementing the techniques of the present application, namely, the image prediction method. Video decoder 30 is operative to receive encoded picture data (e.g., encoded bitstream) 21, e.g., encoded by encoder 20, to obtain decoded picture 231. During the decoding process, video decoder 30 receives video data, such as an encoded video bitstream representing picture blocks of an encoded video slice and associated syntax elements, from video encoder 20.

In the example of fig. 3, decoder 30 includes entropy decoding unit 304, inverse quantization unit 310, inverse transform processing unit 312, reconstruction unit 314 (e.g., summer 314), buffer 316, loop filter 320, decoded picture buffer 330, and 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. In some examples, video decoder 30 may perform a decoding pass that is substantially reciprocal to the encoding pass described with reference to video encoder 20 of fig. 2.

Entropy decoding unit 304 is used to perform entropy decoding on encoded picture data 21 to obtain, for example, quantized coefficients 309 and/or decoded encoding parameters (not shown in fig. 3), e.g., any or all of inter-prediction, intra-prediction parameters, loop filter parameters, and/or other syntax elements (decoded). Entropy decoding unit 304 is further configured to forward inter-prediction parameters, intra-prediction parameters, and/or other syntax elements to prediction processing unit 360. Video decoder 30 may receive syntax elements at the video stripe level and/or the video block level.

Inverse quantization unit 310 may be functionally identical to inverse quantization unit 110, inverse transform processing unit 312 may be functionally identical to inverse transform processing unit 212, reconstruction unit 314 may be functionally identical to reconstruction unit 214, buffer 316 may be functionally identical to buffer 216, loop filter 320 may be functionally identical to loop filter 220, and decoded picture buffer 330 may be functionally identical to 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 typically used to perform block prediction and/or to obtain a prediction block 365 from the encoded data 21, as well as to receive or obtain prediction related parameters and/or information about the selected prediction mode (explicitly or implicitly) from, for example, the entropy decoding unit 304.

When a video slice is encoded as an intra-coded (I) slice, the intra-prediction unit 354 of the prediction processing unit 360 is used to generate a prediction block 365 for a picture block of the current video slice based on the signaled intra-prediction mode and data from a previously decoded block of the current frame or picture. When a video frame is encoded as an inter-coded (i.e., B or P) slice, an inter-prediction unit 344 (e.g., a motion compensation unit) of prediction processing unit 360 is used to generate a prediction block 365 for a video block of the current video slice based on the motion vector and other syntax elements received from entropy decoding unit 304. For inter prediction, a prediction block may be generated from one reference picture within one reference picture list. Video decoder 30 may construct a reference frame list based on the reference pictures stored in DPB 330 using default construction techniques: list 0 and list 1.

The prediction processing unit 360 is configured to determine prediction information for a video block of a current video slice by parsing the motion vector and other syntax elements, and generate a prediction block for the current video block being decoded using the prediction information. For example, prediction processing unit 360 uses some syntax elements received to determine a prediction mode (e.g., intra or inter prediction) for encoding video blocks of a video slice, an inter prediction slice type (e.g., B slice, P slice, or GPB slice), construction information for one or more of the reference picture lists of the slice, motion vectors for each inter-encoded video block of the slice, inter prediction state for each inter-encoded video block of the slice, and other information to decode video blocks of the current video slice.

Inverse quantization unit 310 may be used to inverse quantize (i.e., inverse quantize) the quantized transform coefficients provided in the bitstream and decoded by entropy decoding unit 304. The inverse quantization process may include using quantization parameters calculated by video encoder 20 for each video block in a video stripe to determine the degree of quantization that should be applied and likewise the degree of inverse quantization that should be applied.

The inverse transform processing unit 312 is configured to apply an inverse transform (e.g., an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process) to the transform coefficients in order to generate a residual block in the pixel domain.

A reconstruction unit 314 (e.g., a summer 314) is used to add the inverse transform block 313 (i.e., the reconstructed residual block 313) to the prediction block 365 to obtain a reconstructed block 315 in the sample domain, e.g., by adding sample values of the reconstructed residual block 313 to sample values of the prediction block 365.

Loop filter unit 320 is used (during or after the encoding cycle) to filter reconstructed block 315 to obtain filtered block 321, to smooth pixel transitions or improve video quality. In one example, loop filter unit 320 may be used to perform any combination of the filtering techniques described below. Loop filter unit 320 is intended to represent one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or other filters, such as a bilateral filter, an adaptive loop filter (adaptive loop filter, ALF), or a sharpening or smoothing filter, or a collaborative filter. Although loop filter unit 320 is shown in fig. 3 as an in-loop filter, in other configurations loop filter unit 320 may be implemented as a post-loop filter.

The decoded video blocks 321 in a given frame or picture are then stored in a decoded picture buffer 330 that stores reference pictures for subsequent motion compensation.

Decoder 30 is for outputting decoded picture 31, e.g., via output 332, for presentation to a user or for viewing by a user.

Other variations of video decoder 30 may be used to decode the compressed bitstream. For example, decoder 30 may generate the output video stream without loop filter unit 320. For example, the non-transform based decoder 30 may directly inverse quantize the residual signal without an inverse transform processing unit 312 for certain blocks or frames. In another embodiment, the video decoder 30 may have an inverse quantization unit 310 and an inverse transform processing unit 312 combined into a single unit.

Fig. 4 is an illustration of an example of a video encoding system 40 including encoder 20 of fig. 2 and/or decoder 30 of fig. 3, according to an example embodiment. The system 40 may implement a combination of the various techniques of the present application. In the illustrated embodiment, video encoding system 40 may include an imaging device 41, a video encoder 20, a video decoder 30 (and/or a video encoder implemented by logic circuitry 47 of a processing unit 46), an antenna 42, one or more processors 43, one or more memories 44, and/or a display device 45.

As shown, imaging device 41, antenna 42, processing unit 46, logic 47, video encoder 20, video decoder 30, processor 43, memory 44, and/or display device 45 are capable of communicating with each other. As discussed, although video encoding system 40 is depicted with video encoder 20 and video decoder 30, in different examples, video encoding system 40 may include only video encoder 20 or only video decoder 30.

In some examples, as shown, video encoding system 40 may include an antenna 42. For example, the antenna 42 may be used to transmit or receive an encoded bitstream of video data. Additionally, in some examples, video encoding system 40 may include a display device 45. The display device 45 may be used to present video data. In some examples, as shown, logic circuitry 47 may be implemented by processing unit 46. The processing unit 46 may comprise application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, or the like. The video encoding system 40 may also include an optional processor 43, which optional processor 43 may similarly include application-specific integrated circuit (ASIC) logic, a graphics processor, a general purpose processor, or the like. In some examples, logic 47 may be implemented in hardware, such as video encoding dedicated hardware, processor 43 may be implemented in general purpose software, an operating system, or the like. In addition, the memory 44 may be any type of memory, such as volatile memory (e.g., static random access memory (Static Random Access Memory, SRAM), dynamic random access memory (Dynamic Random Access Memory, DRAM), etc.) or non-volatile memory (e.g., flash memory, etc.), and the like. In a non-limiting example, the memory 44 may be implemented by an overspeed cache. In some examples, logic circuitry 47 may access memory 44 (e.g., for implementing an image buffer). In other examples, logic 47 and/or processing unit 46 may include memory (e.g., a cache, etc.) for implementing an image buffer, etc.

In some examples, video encoder 20 implemented by logic circuitry may include an image buffer (e.g., implemented by processing unit 46 or memory 44) and a graphics processing unit (e.g., implemented by processing unit 46). The graphics processing unit may be communicatively coupled to the image buffer. The graphics processing unit may include video encoder 20 implemented by logic circuitry 47 to implement the various modules discussed with reference to fig. 2 and/or any other encoder system or subsystem described herein. Logic circuitry may be used to perform various operations discussed herein.

Video decoder 30 may be implemented in a similar manner by logic circuit 47 to implement the various modules discussed with reference to decoder 30 of fig. 3 and/or any other decoder system or subsystem described herein. In some examples, video decoder 30 implemented by logic circuitry may include an image buffer (implemented by processing unit 2820 or memory 44) and a graphics processing unit (e.g., implemented by processing unit 46). The graphics processing unit may be communicatively coupled to the image buffer. The graphics processing unit may include video decoder 30 implemented by logic circuit 47 to implement the various modules discussed with reference to fig. 3 and/or any other decoder system or subsystem described herein.

In some examples, antenna 42 of video encoding system 40 may be used to receive an encoded bitstream of video data. As discussed, the encoded bitstream may include data related to the encoded video frame, indicators, index values, mode selection data, etc., discussed herein, such as data related to the encoded partitions (e.g., transform coefficients or quantized transform coefficients, optional indicators (as discussed), and/or data defining the encoded partitions). Video encoding system 40 may also include a video decoder 30 coupled to antenna 42 and used to decode the encoded bitstream. The display device 45 is used to present video frames.

Fig. 5 is a simplified block diagram of an apparatus 500 that may be used as either or both of the source device 12 and the destination device 14 in fig. 1, according to an example embodiment. Apparatus 500 may implement the techniques of this application for image prediction, and apparatus 500 may take the form of a computing system comprising multiple computing devices, or a single computing device such as a mobile phone, tablet, laptop, notebook, desktop, or the like.

The processor 502 in the apparatus 500 may be a central processor. Processor 502 may be any other type of device or devices capable of manipulating or processing information, either as is known or later developed. As shown, while the disclosed embodiments may be practiced with a single processor, such as processor 502, advantages in speed and efficiency may be realized with more than one processor.

In an embodiment, the Memory 504 in the apparatus 500 may be a Read Only Memory (ROM) device or a random access Memory (random access Memory, RAM) device. Any other suitable type of storage device may be used as memory 504. Memory 504 may include code and data 506 that is accessed by processor 502 using bus 512. Memory 504 may further include an operating system 508 and an application 510, application 510 containing at least one program that permits processor 502 to perform the methods described herein. For example, application 510 may include applications 1 through N, applications 1 through N further including video encoding applications that perform the methods described herein. The apparatus 500 may also contain additional memory in the form of a secondary memory 514, which secondary memory 514 may be, for example, a memory card for use with a mobile computing device. Because video communication sessions may contain a large amount of information, such information may be stored in whole or in part in slave memory 514 and loaded into memory 504 for processing as needed.

The apparatus 500 may also include one or more output devices, such as a display 518. In one example, display 518 may be a touch-sensitive display that combines the display and touch-sensitive elements operable to sense touch inputs. A display 518 may be coupled to the processor 502 by a bus 512. Other output devices may be provided in addition to the display 518 that permit a user to program or otherwise use the apparatus 500, or other output devices may be provided as alternatives to the display 518. When the output device is a display or comprises a display, the display may be implemented in different ways, including by a liquid crystal display (liquid crystal display, LCD), cathode-ray tube (CRT) display, plasma display or light emitting diode (light emitting diode, LED) display, such as an Organic LED (OLED) display.

The apparatus 500 may also include or be in communication with an image sensing device 520, the image sensing device 520 being, for example, a camera or any other image sensing device 520 now available or hereafter developed that can sense images, such as images of a user operating the apparatus 500. The image sensing device 520 may be placed directly facing the user running the apparatus 500. In an example, the position and optical axis of the image sensing device 520 may be configured such that its field of view includes an area proximate to the display 518 and the display 518 is visible from that area.

The apparatus 500 may also include or be in communication with a sound sensing device 522, such as a microphone or any other sound sensing device now available or later developed that may sense sound in the vicinity of the apparatus 500. The sound sensing device 522 may be placed directly facing the user operating the apparatus 500 and may be used to receive sounds, such as speech or other sounds, emitted by the user while operating the apparatus 500.

Although the processor 502 and the memory 504 of the apparatus 500 are depicted in fig. 5 as being integrated in a single unit, other configurations may also be used. The operations of processor 502 may be distributed among a plurality of directly couplable machines, each having one or more processors, or distributed in a local area or other network. The memory 504 may be distributed across multiple machines, such as network-based memory or memory in multiple machines running the apparatus 500. Although depicted here as a single bus, the bus 512 of the apparatus 500 may be formed from multiple buses. Further, slave memory 514 may be coupled directly to other components of apparatus 500 or may be accessible over a network, and may comprise a single integrated unit, such as a memory card, or multiple units, such as multiple memory cards. Thus, the apparatus 500 may be implemented in a variety of configurations. The terms referred to in this application are briefly described below:

Intra prediction coding: and a coding mode for predicting the current pixel value by using the surrounding adjacent pixel values and then coding the prediction error.

Encoding a picture: the coded representation of the picture contains all the coded tree units of the picture.

Motion Vector (MV): a two-dimensional vector for inter prediction that provides an offset from coordinates in the decoded picture to coordinates in the reference picture.

Prediction block: rectangular mxn sample blocks on which the same prediction is applied.

The prediction process comprises the following steps: the predicted value is used to provide an estimate of the data element (e.g., sample value or motion vector) currently being decoded.

Predicted value: a specified value or a combination of previously decoded data elements (e.g., sample values or motion vectors) used in a subsequent data element decoding process.

Reference frame: pictures or frames that are short-term reference pictures or long-term reference pictures. The reference frame contains samples that can be used for inter prediction in decoding order in the decoding process of the subsequent picture.

Inter prediction: a predicted image of the current block is generated by indicating a position of a pixel for prediction in a reference frame by a motion vector according to the pixel in the reference frame of the current block.

Bi-prediction (B) slice: intra prediction or inter prediction may be used to predict slices decoded with up to two motion vectors and a reference index for sample values for each block.

CTU: a coding tree unit (coding tree unit) in which an image is composed of a plurality of CTUs, and a CTU generally corresponds to a square image area, and includes luminance pixels and chrominance pixels (or may include only luminance pixels or may include only chrominance pixels) in the image area; the CTU also contains syntax elements indicating how the CTU is divided into at least one Coding Unit (CU), and a method of decoding each coding unit to obtain a reconstructed image.

CU: the coding unit, corresponding to a rectangular area of a×b in the image, comprises a×b luminance pixel or/and its corresponding chrominance pixel, a is rectangular wide, B is rectangular high, a and B may be the same or different, and the values of a and B are usually integers of power of 2, such as 128, 64, 32, 16, 8, 4. One coding unit comprises a predicted image and a residual image, and the predicted image and the residual image are added to obtain a reconstructed image of the coding unit. The prediction image is generated by intra prediction or inter prediction, and the residual image is generated by performing inverse quantization and inverse transformation processing on the transform coefficient.

VTM: the jfet organization developed new codec reference software.

Fusion coding (merge): an inter-frame coding method, in which motion vectors are not directly transmitted in a code stream. The current block may select a corresponding fusion candidate from the fusion candidate list (merge candidate list) according to a fusion sequence number (merge index), and use motion information of the fusion candidate as motion information of the current block, or use the motion information of the fusion candidate as motion information of the current block after scaling.

The image prediction method described in the present application relates to inter prediction, and the multi-hypothesis method is an inter prediction method. Inter prediction is briefly described below, and is mainly utilized in video encoding and decoding to eliminate temporal and spatial redundancy in video.

Inter prediction is a prediction technique based on motion compensation (motion compensation). In inter-prediction coding, each frame of an image sequence can be divided into a number of mutually non-overlapping blocks due to some temporal correlation of identical objects in neighboring frames of the image, and the motion of all pixels within a block is considered to be identical. The main process is to determine motion information of a current block, acquire a reference image block from a reference frame according to the motion information, and generate a predicted image of the current block. The motion information includes inter prediction direction, reference frame index (ref_idx), motion Vector (MV), etc., and the inter prediction indicates which prediction direction of forward prediction, backward prediction, or bi-directional prediction the current block uses through the inter prediction direction, indicates a reference frame (reference frame) through the reference frame index (reference index), and indicates a positional offset of a reference block (reference block) of the current block (current block) in the reference frame with respect to the current block in the current frame through the motion vector. The motion vector indicates a displacement vector of a reference picture block for predicting a current block with respect to the current block in the reference frame, and thus one motion vector corresponds to one reference picture block.

In encoding, video encoding standards such as h.265/HEVC and h.266/VVC divide a frame of image into Coding Tree Units (CTUs) that do not overlap each other, and one CTU is divided into one or more Coding Units (CUs). One CU contains coding information including information of prediction modes, transform coefficients, and the like. Decoding end: and carrying out corresponding decoding processing such as prediction, inverse quantization, inverse transformation and the like on the CU according to the coding information to generate a reconstructed image corresponding to the CU.

In the code stream, motion information occupies a large amount of data. To reduce the amount of data required, motion information is typically transmitted in a predictive manner. The population can be divided into two modes, inter and merge:

intermvp mode: the transmitted motion information contains: inter prediction direction (forward, backward, or bi-directional), reference frame index, motion vector predictor index, and motion vector residual. For motion vector information in motion information, a mode of transmitting a difference value between an actual motion vector and a motion vector predicted value (motion vector predictor, MVP) is generally adopted, and a motion vector residual value (motion vector difference, MVD) between the MVP and the actual motion vector is transmitted to a decoding end by an encoding end. Wherein motion vector prediction may comprise a plurality of predictors, a motion vector prediction candidate list (MVP candidate list) is constructed in the same manner as in the encoding section and decoding section, and a motion vector predictor index (motion vector predictor index, MVP index) is delivered to the decoding end.

Merge mode: the fused motion information candidate list (merge candidate list) is constructed in the same manner in the encoding section and decoding section, and the index is delivered to the decoding end. A fusion index (merge index) is transmitted in the code stream. The motion information in the motion information candidate list (candidate list) is typically obtained from its spatial neighboring blocks or temporal blocks in the reference frame, wherein the candidate motion information derived from the motion information of the image block neighboring the current block is called spatial candidate (spatial candidate) and the motion information of the corresponding position image block derived from the current block in the reference image is called temporal candidate (temporal candidate).

The Bi-directional optical flow (Bi-directional Optical flow, BIO) is an inter-frame coding method (JVET-E1001 proposal, JVET-K0255 proposal, JVET-K0119 proposal and other related technical proposals) for optimizing and improving pixel-level motion vectors on the basis of a block-based motion compensation technology. The bi-directional optical flow technique can provide improved motion vectors at the pixel level without the need for additional tedious searches or additional code stream information. The bi-directional optical flow technique combines the motion trajectories of each pixel with an optical flow field and Hermite (Hermite) interpolation analysis to derive improved motion vectors by minimizing the intersection of the motion trajectories with the reference frame plane. In the process, the horizontal gradient and the vertical gradient of each pixel in the prediction block are required to be utilized, and a special 6-tap filter is also required to conduct interpolation operation on the gradient.

The decoding side motion vector improvement (Decoder-side motion vector refinement, DMVR) is an inter-frame coding method (jfet-E1001 proposal, jfet-K0275 proposal, etc.) for adjusting the existing motion vector by searching at the decoding side. The decoding side motion vector improvement technique is used on coded blocks that utilize bi-directional modes for inter prediction. At the decoding end, a bi-directional template is obtained by using two prediction blocks generated by motion compensation by using the motion vector MV0 of list0 and the motion vector MV1 of list1 transmitted in the initial code stream. Searching around the positions indicated by the initial motion vectors MV0 and MV1 in the reference frames of list0 and list1 by using a bidirectional template, and finding the position with the minimum matching distortion in the searching range as new MV0 and MV1 and two new prediction blocks. The final prediction block is generated using the new prediction block weights.

In HEVC and the previous standards, reference frames are divided into two groups, forward and backward, placed in two reference frame lists (reference picture list), commonly named list0 and list1, respectively. The prediction direction of which of forward prediction, backward prediction or bi-prediction is used for the current block is indicated by the inter-prediction direction, and different reference frame lists list0, list1 or list0 and list1 are selected to be used according to the prediction direction. For the selected reference frame list, the reference frame is indicated by a reference frame index. In the selected reference frame, the position offset of the predicted block of the current block in the reference frame relative to the current block in the current frame is indicated by the motion vector. The final prediction block is then generated using the prediction blocks taken from the list0, list1, or reference frames in list0 and list1, depending on the prediction direction. Wherein when the prediction direction is unidirectional, the prediction blocks obtained from the reference frames in list0 or list1 are directly used, and when the prediction direction is bidirectional, the prediction blocks obtained from the reference frames in list0 and list1 are synthesized into a final prediction block by means of weighted average. In the Multi-Hypothesis inter coding (Multi-Hypothesis Inter Prediction) method, a predicted block or a final predicted block is taken as an original Hypothesis (Hypothesis) of a current block, and the number of hypotheses is increased by adding new motion information or prediction information to improve coding performance. jfet-K0269 and jfet-K0257 propose to use multi-hypothesis inter-coding methods, but each implement multi-hypothesis inter-coding in a different way.

The multi-hypothesis coding method in the JVET-K0269 proposal adds additional hypotheses by additionally transmitting motion information on the basis of inter-frame coding in the original HEVC or VVC VTM. Each additional hypothesis needs to transmit a flag (additional hypothesis flag) of whether there is an additional hypothesis, a reference frame number (ref idx add hyp) of the additional hypothesis, motion vector predictor information (mvp add hyp flag) of the additional hypothesis, motion vector difference values of the additional hypothesis, and weighting coefficients of the additional hypothesis (add hyp weight idx). The meaning of the additionally assumed reference frame number, motion vector predictor information, and motion vector disparity value are the same as in HEVC and the previous standards, but the reference frame list is generated in a different manner. The list of additional hypothetical reference frames is generated using alternating list0 and list1 insertion in HEVC or VVC VTM, wherein duplicate reference frames are no longer added to the list. After the prediction block (extra hypothesis) is obtained from the motion information of the extra hypothesis, it is compared with the original final prediction block (original hypothesis) using the weighting coefficients of the extra hypothesis. The weighting coefficients for the additional hypotheses are two, 1/4 and-1/8, respectively.

The image prediction method is used for predicting at least one image block using inter prediction in an image by using a current method, so as to obtain a predicted image block. Subsequently, further decoding processing can be performed based on the obtained predicted image block to obtain a reconstructed image of the image block, the processing in the encoding side and the decoding side being identical. The following describes an example of the decoding side. For implementation of the encoding side, please refer to the encoding flow described above and the method flow of the decoding side described below. For example, the encoding end obtains multi-hypothesis coding information of the image block to be encoded in a multi-hypothesis coding information list by traversal, wherein the multi-hypothesis coding information comprises an identification for representing a division mode of the multi-hypothesis coding method and parameters of the multi-hypothesis coding method. The division mode is used for dividing the prediction blocks of multiple hypotheses of one picture to be coded when a multi-hypothesis coding method is adopted. For example, the division mode is triangle division, the parameter is the direction of triangle division, the division mode is square division, and the parameter is a weighting coefficient.

The triangularization can be referred to as a multi-hypothesis coding method in the jfet-K0144 proposal. On the basis of inter-frame coding in the original HEVC or VVC VTM, when the current coding block is merge or skip, dividing the coding block into two triangular coding blocks along the diagonal direction, wherein each triangular coding block uses independent motion information obtained from a fusion motion information candidate list. The combination of the division direction and the selection of the fusion motion information candidates of the two triangular coding blocks is selected from a preset multi-hypothesis fusion motion information candidate selection and division combination list using one combination sequence number, and the sequence number is transmitted in the code stream. The two triangular code blocks have a certain overlapping area and are weighted by a weighting coefficient related to the distance.

Square partitioning can be referred to the jfet-K0257 proposal, in which a combination coding scheme is used to implement multi-hypothesis coding, combining merge with inter MVP, merge, and intra coding. When the current original hypothesis/first hypothesis is the inter MVP mode and the unidirectional approach (i.e., list0 or list1 only) is used, the merge mode is used to generate additional hypotheses. When the current original hypothesis/first hypothesis is in the merge mode, the next merged motion information candidate selected by the original hypothesis/first hypothesis in the merged motion information candidate list may be used as motion information of the additional hypothesis to generate the additional hypothesis. When the current original hypothesis/first hypothesis is the merge mode, an additional hypothesis may also be generated using the intra coding mode, with an additional syntax element identifying whether the mode is used. After the prediction block (additional hypothesis) is taken, it is compared to the original final prediction block using weighting coefficients. In the jfet-K0257 proposal, the weighting coefficients and manner are related to a combination of multiple hypotheses.

The reference frame list generation process is the prior art, and the process may be performed by adopting the same method as HEVC (i.e. constructing list0 and list1 at the beginning of SLICE (SLICE)), or other reference frame list generation methods (such as the method in jfet-K0269), which is not limited by the present invention. To improve efficiency, multi-hypothesis coding methods (e.g., jfet-K0269 proposal and jfet-K0257 proposal) add additional predictions beyond the original set of forward, backward, or bi-directional predictions (first hypothesis), which are referred to herein as additional hypotheses, which may include a second hypothesis, a third hypothesis, etc. In the present invention, the original set of forward, backward, or bi-directional predictions is referred to as the original hypothesis or first hypothesis.

The image prediction method described in the present application is described below with reference to fig. 6. The image prediction method comprises the following steps: 602: and analyzing the code stream to obtain the multi-hypothesis information index of the current image block to be decoded.

602 corresponds to step 1 mentioned below. The multi-hypothesis information index is multi-hypothesis pattern information mentioned below.

604: according to the multi-hypothesis information index, obtaining first multi-hypothesis information corresponding to the current image block from a multi-hypothesis information list, wherein the first multi-hypothesis information comprises a motion information index and a first identifier, the motion information index of the first multi-hypothesis information indicates multi-hypothesis motion information of the current image block to be decoded, the first identifier indicates a first division mode of a multi-hypothesis method, and the first multi-hypothesis information further comprises parameters of the first division mode.

In one possible implementation manner, the first division manner is triangle division, the parameter of the first division manner indicates a division direction of the triangle division, the second division manner is square division, and the parameter of the second division manner indicates a weighting coefficient of the square division. Of course, the second division mode may be triangle division, the parameter of the second division mode indicates the division direction of the triangle division, the first division mode is square division, and the parameter of the first division mode indicates the weighting coefficient of the square division.

606: and performing motion compensation according to the motion information of the multi-hypothesis coding of the current image block to be decoded so as to obtain a multi-hypothesis predicted image block.

604 and 606 correspond to step 2 below.

608: and processing the plurality of hypothetical predicted image blocks by using the first division mode according to the first identifier and the parameters of the first division mode to obtain the predicted image block of the current image block to be decoded.

608 corresponds to step 3 below. The predicted image block of the current image block to be decoded may also be referred to as a final inter predicted image of the current image block to be decoded.

The process of obtaining a decoded data block using the image prediction method corresponding to fig. 6 is specifically described below. For further details regarding the implementation of the above-described image prediction method, reference may be made to the following detailed description. In the following procedure, the current block is the current image block described above.

The decoding process includes steps 1 to 4. The block that is performing the decoding process is referred to as a current block.

Step 1: analyzing the code stream of the current block to obtain the prediction mode information of the current block

Specifically, the mode information of the current block includes, but is not limited to, coding information such as merge, skip, inter mode information, multi-hypothesis mode information, and the like.

Step 2: acquiring motion information of a current block according to prediction mode information of the current block;

And if the current block adopts the multi-hypothesis coding mode according to the multi-hypothesis mode information, obtaining multi-hypothesis information of the current block.

The method specifically comprises the following steps:

and generating a fusion motion information candidate list. The method specifically comprises the following steps: the spatial candidate and the temporal candidate of the current block are added into a fusion motion information candidate list of the current block, and the method is the same as that in HEVC. As shown in fig. 1, the spatial fusion candidates include A0, A1, B0, B1, and B2, and the temporal fusion candidates include T0 and T1. In VTM, temporal fusion candidates also include candidates provided by Adaptive Temporal Motion Vector Prediction (ATMVP) techniques. The invention does not relate to a process related to generating a candidate list of fused motion information, and the process can be performed by adopting a method in HEVC or VTM, and can also adopt other methods for generating the candidate list of fused motion information, such as a method in JVET-K0257.

Then, two hypothesized motion information and multi-hypothesized motion compensation information are acquired, and the decoding end: the multi-hypothesis information corresponding to the current block is determined from a multi-hypothesis information list (hereinafter also referred to as a combination list of multi-hypothesis combination mode and motion information) according to the multi-hypothesis information index carried in the code stream. Each multi-hypothesis information in the multi-hypothesis information list comprises: a motion index, in particular a fused motion information candidate list index of a first hypothesis (i.e. the original hypothesis of the preamble) and a fused motion information candidate list index of a second hypothesis (i.e. the additional hypothesis of the preamble), a partition mode identity (i.e. the first identity or the second identity of the preamble) and partition mode information (i.e. the parameters of the first partition mode or the parameters of the second partition mode of the preamble).

And confirming the motion information of the first hypothesis from the fusion motion information candidate list according to the fusion motion information candidate list index of the first hypothesis in the multi-hypothesis information corresponding to the current block. And confirming the motion information of the second hypothesis from the fusion motion information candidate list according to the fusion motion information candidate list index of the second hypothesis in the multi-hypothesis information corresponding to the current block. The division mode identification is used for indicating that the division mode is triangular division or square division, and when the division mode identification indicates that the division mode is triangular division, the division mode information indicates the division direction of the triangular division mode; when the division pattern identification indicates that the division pattern is a square division, the division pattern information indicates a weighting coefficient of the square division.

The division mode identification is used for indicating that the division mode is triangular division or square division, and when the division mode identification indicates that the division mode is triangular division, the division mode information indicates the division direction of the triangular division mode; when the division pattern identification indicates that the division pattern is a square division, the division pattern information indicates a weighting coefficient of the square division.

The multi-hypothesis information list, i.e., combination [ ], that includes, but is not limited to, examples wherein one example includes a plurality of combinations, wherein each combination includes { parameters of triangle partition mode or square partition mode, first hypothesis fused motion information candidate list index, second hypothesis fused motion information candidate list index, partition mode flag bit }. Of course, the present application does not limit the order of the four parameters in each combination, i.e., the order of the indicated information in the examples not listed, may be different.

In the present application, when dividing square, the fused motion information candidate list index of the first hypothesis and the fused motion information candidate list index of the second hypothesis use preset index combinations, including but not limited to index, index+1 combinations, and index+m, index+n combinations, where m and n are both smaller than the length of the fused motion information candidate list, and m is not equal to n, and, because in the parameter list of triangle division, there are multiple specific implementation manners stored, for example, about 40 kinds of implementation manners can be selected or specified randomly, which are used as parameters of triangle division in the multi-hypothesis information list described in the present application.

Each of examples one through four includes 10 pieces of multi-hypothesis information.

Example one:

combination[]＝

{

{0,1,0,0},{1,0,1,0},{0,1,2,0},{1,1,0,1},{1,0,2,0},

{1,1,2,1},{0,2,0,0},{0,3,0,1},{0,1,3,0},{0,2,1,0},

}

example two:

combination[]＝

{

{0,1,0,0},{1,0,1,1},{0,1,2,0},{1,1,0,0},{1,0,2,0},

{1,1,2,1},{0,2,0,1},{0,3,0,0},{0,1,3,0},{0,2,1,0}

}

example three:

combination[]＝

{

{0,1,0,0},{1,0,1,1},{1,0,1,0},{0,1,2,0},{0,1,2,1},

{1,1,0,0},{1,0,2,0},{1,1,2,0},{0,3,0,0},{0,3,0,1}

}

example four:

combination[]＝

{

{0,1,0,0},{0,1,0,1},{1,0,1,0},{1,0,1,1},{0,1,2,0},

{0,1,2,1},{1,1,0,0},{1,1,0,1},{1,1,0,0},{1,1,0,1}

}

if all the image blocks to be decoded are divided by using only triangles, the dividing modes are more (more than 40), and compared with the triangles, the triangles have high processing complexity, so that the efficiency of obtaining the predicted image block of the current block is lower. If all the image blocks to be decoded only use square division mode, the motion information combination mode of the additional hypothesis is limited, and the original hypothesis and the additional hypothesis both use square division, the multi-hypothesis fusion mode is single, and the coding and decoding effects are bad. In the application, only 10 specific division modes (one piece of multi-hypothesis information corresponds to one division mode) are needed for one combination, so that the coding and decoding requirements can be met, the complexity is reduced compared with single-use triangle division, and the decoding efficiency and the decoding performance can be guaranteed.

With the method of the present application, since the code stream carries the division identifier indicating the multi-hypothesis method, the decoding end can determine which division mode is used to predict the image in the multi-hypothesis method, that is, different division modes can be used to obtain the prediction block of the image block for different image blocks, so that the image block can use the division mode more suitable for the characteristics of the image block, thereby improving the efficiency of image prediction and reducing the decoding time.

If the current block is obtained according to the multi-hypothesis mode information and does not adopt the multi-hypothesis coding mode, executing:

and if the current block is in the merge/skip mode, generating a fusion motion information candidate list. The method specifically comprises the following steps: the spatial candidate and the temporal candidate of the current block are added into a fusion motion information candidate list of the current block, and the method is the same as that in HEVC. As shown in fig. 1, the spatial fusion candidates include A0, A1, B0, B1, and B2, and the temporal fusion candidates include T0 and T1. In VTM, temporal fusion candidates also include candidates provided by Adaptive Temporal Motion Vector Prediction (ATMVP) techniques. The invention does not relate to a process related to generating the fusion motion information candidate list, and the process can be performed by adopting a method in HEVC or VTM, and can also adopt other methods for generating the fusion motion information candidate list. If the current block is in Inter MVP mode, a motion vector prediction candidate list is generated, which may be performed by using a method in HEVC or VTM in the prior art, or other methods for generating a motion vector prediction candidate list.

Then, motion information of the first hypothesis is acquired, and the decoding end: if the current block is in the merge/skip mode, determining the motion information of the current block according to the fusion index carried in the code stream. If the current block is in the Inter MVP mode, determining the motion information of the current block according to the Inter-frame prediction direction, the reference frame index, the motion vector predicted value index and the motion vector residual value transmitted in the code stream.

Step 3: inter prediction is performed based on motion information of the first hypothesis and the second hypothesis, and the partition mode identification and the partition mode information, to obtain a predicted image of the current block.

Wherein, the current block is obtained according to the multi-hypothesis mode information and adopts a multi-hypothesis coding mode.

And respectively obtaining predicted images of the first hypothesis and the second hypothesis by using the motion information of the first hypothesis and the second hypothesis. Decoding end: and locating the reference blocks of the first hypothesis and the second hypothesis from the reference frames by using the reference frame direction, the reference frame sequence number and the motion vector in the motion information of the first hypothesis and the second hypothesis, and obtaining the prediction blocks of the first hypothesis and the second hypothesis according to the multi-hypothesis combined mode information. The reference frame direction is forward prediction, which means that the current coding unit selects one reference image from the forward reference image set to acquire a reference block. The reference frame direction is backward prediction, which means that the current coding unit selects one reference image from the backward reference image set to acquire a reference block. The reference frame direction is bi-predictive, meaning that one reference picture is selected from each of the forward and backward reference picture sets to obtain a reference block. When using the bi-prediction method, the current coding unit may have two reference blocks, each of which requires a motion vector and a reference frame index to indicate.

And then determining the pixel value of the pixel point in the prediction block of the current block according to the pixel value of the pixel point in the reference block. More specifically, one of the following methods is followed:

the method comprises the following steps: when the triangular multi-hypothesis mode is used, the triangular prediction blocks of the first hypothesis and the second hypothesis are obtained according to the multi-hypothesis direction, and the final prediction image is generated from the first hypothesis and the second hypothesis using a preset weighting coefficient, which may be performed with reference to jfet-K0144, which is not limited in the present invention. When the square multi-hypothesis mode is used, square prediction blocks of the first hypothesis and the second hypothesis are obtained, final prediction images are generated from the first hypothesis and the second hypothesis using preset weighting coefficients, which may be performed with reference to jfet-K0257, and the present invention is not limited thereto.

The method comprises the following steps: when the triangular multi-hypothesis mode is used, square prediction blocks of the first hypothesis and the second hypothesis are obtained according to the multi-hypothesis direction, a final prediction image is generated from the first hypothesis and the second hypothesis using a preset weighting coefficient, which may be performed with reference to jfet-K0144 using a triangular weighting coefficient matrix, and the present invention is not limited thereto. When the square multi-hypothesis mode is used, square prediction blocks of the first hypothesis and the second hypothesis are obtained, final prediction images are generated from the first hypothesis and the second hypothesis using preset weighting coefficients, which may be performed with reference to jfet-K0257, and the present invention is not limited thereto.

If the current block is obtained according to the multi-hypothesis mode information and does not adopt the multi-hypothesis coding mode, inter prediction is performed by utilizing the motion information of the first hypothesis, and a predicted image of the current block is obtained.

Decoding end: and obtaining the predicted block from the reference frame by using the reference frame direction, the reference frame sequence number and the motion vector. The reference frame direction is forward prediction, which means that the current coding unit selects one reference image from the forward reference image set to acquire a reference block. The reference frame direction is backward prediction, which means that the current coding unit selects one reference image from the backward reference image set to acquire a reference block. The reference frame direction is bi-predictive, meaning that one reference picture is selected from each of the forward and backward reference picture sets to obtain a reference block. When using the bi-prediction method, the current coding unit may have two reference blocks, each of which requires a motion vector and a reference frame index to indicate. And then determining the pixel value of the pixel point in the prediction block of the current block according to the pixel value of the pixel point in the reference block. The above may be performed by using a method in HEVC or VTM, or other methods for generating a motion vector prediction candidate list, which is not limited by the present invention.

Step 4: adding the final inter-frame predicted image of the current block (namely the predicted image block of the current image block to be decoded) and the residual image to obtain a reconstructed image of the current block;

decoding end: if the current block has residual errors, adding the residual error information and the predicted image to obtain a reconstructed image of the current block; if the current block has no residual, the predicted image is a reconstructed image of the current block.

The above process is in the prior art, for example, the same method as HEVC or VTM may be used, or other motion compensation and image reconstruction methods may be used, which is not limited by the present invention.

The present application also describes an image prediction apparatus which may be used to perform the above-described image prediction method.

In one implementation, the image prediction apparatus includes: a memory for storing video data in the form of a code stream, the video data comprising one or more image blocks; a video decoder for performing the above-mentioned image prediction methods (e.g. corresponding to fig. 6) and decoding methods, and in one implementation, the video decoder is configured to parse the code stream to obtain a multi-hypothesis information index of the current image block to be decoded; obtaining first multi-hypothesis information corresponding to the current image block from a multi-hypothesis information list according to the multi-hypothesis information index, wherein the first multi-hypothesis information comprises a motion information index and a first identifier, the motion information index of the first multi-hypothesis information indicates multi-hypothesis motion information of the current image block to be decoded, the first identifier indicates a first division mode of a multi-hypothesis method, and the first multi-hypothesis information further comprises parameters of the first division mode; performing motion compensation according to the motion information of the multi-hypothesis coding of the current image block to be decoded to obtain a plurality of hypothesized predicted image blocks; and processing the plurality of hypothetical predicted image blocks by using the first division mode according to the first identifier and the parameters of the first division mode to obtain the predicted image block of the current image block to be decoded.

Of course, the video decoder may also perform other various implementations of the method corresponding to fig. 6, which are not described here again. In addition, it is apparent that the video decoder may be implemented by the processor in fig. 5 running code in the memory in fig. 5.

In another implementation, as shown in fig. 7, the image prediction apparatus 700 includes an parsing module 701 configured to parse a code stream to obtain a multi-hypothesis information index of a current image block to be decoded.

The first query module 702 is configured to obtain, from a multi-hypothesis information list, first multi-hypothesis information corresponding to the current image block according to the multi-hypothesis information index, where the first multi-hypothesis information includes a motion information index and a first identifier, the motion information index of the first multi-hypothesis information indicates multi-hypothesis motion information of the current image block to be decoded, the first identifier indicates a first division manner of a multi-hypothesis method, and the first multi-hypothesis information further includes parameters of the first division manner.

The motion compensation module 703 is configured to perform motion compensation according to the motion information of the multi-hypothesis coding of the current image block to be decoded, so as to obtain a multi-hypothesis predicted image block.

The partition processing module 704 is configured to process the plurality of hypothetical predicted image blocks using the first partition mode according to the first identifier and the parameter of the first partition mode, so as to obtain a predicted image block of the current image block to be decoded.

The above modules are only schematically divided, and the functions of a plurality of modules may be implemented by one module in actual implementation.

The image prediction apparatus 700 may perform the method corresponding to fig. 6 and other various implementations of the foregoing various methods, which are not described herein.

With the image prediction device, since the code stream carries the division identifier indicating the multi-hypothesis method, the decoding end can determine which division mode is used for predicting the image in the multi-hypothesis method, that is, different division modes can be used for different image blocks to obtain the prediction block of the image block, so that the image block can use the division mode which is more suitable for the characteristics of the image block, thereby improving the image prediction efficiency and reducing the decoding time.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a read-only memory (ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An image encoding method, characterized in that the image encoding method comprises:

obtaining prediction mode information, a first list index, a second list index and parameters of a first division mode of a current image block;

obtaining a fusion motion information candidate list according to the prediction mode information;

confirming first motion information from a fused motion information candidate list according to the first list index;

confirming second motion information from the fused motion information candidate list according to the second list index;

the first list index and the second list index indicate the motion information of the current block, and the parameters of the first division mode indicate the division mode of the current image block;

obtaining a plurality of predicted image blocks according to the first list index, the second list index and the parameters of the first division mode;

obtaining a predicted image block of the current image block according to the plurality of predicted image blocks;

and encoding parameters of the prediction mode information, the first list index, the second list index and the first division mode into a code stream.

2. The method of claim 1, the first list index and the second list index being different values.

3. A method according to any one of claims 1 to 2, wherein the first division is a triangle division, and the parameter of the first division indicates a division direction of the triangle division.

4. A method according to any one of claims 1 to 2, wherein the first division is a square division, and wherein the parameter of the first division indicates a weighting factor of the square division.

5. The method according to any one of claims 1 to 4, wherein the first list index, the second list index indicate motion information of the current block, comprising:

according to the first list index, the original motion information is obtained from a first candidate motion information list of the current image block, and according to the second list index, additional motion information is obtained from the first candidate motion information list of the current image block.

6. An image decoding method, characterized in that the image encoding method comprises:

analyzing the code stream to obtain prediction mode information, a first list index, a second list index and parameters of a first division mode of the current image block;

the first list index and the second list index indicate motion information of the current block, and the parameters of the first division mode indicate the division mode of the current image block;

and obtaining the predicted image block of the current image block according to the plurality of predicted image blocks.

7. The method of claim 6, the first list index and the second list index being different values.

8. The method according to any one of claims 6 to 7, wherein the first division manner is a triangle division, and a parameter of the first division manner indicates a division direction of the triangle division.

9. The method according to any of claims 6 to 7, wherein the first division is a square division, and wherein a parameter of the first division indicates a weighting factor of the square division.

10. The method according to any one of claims 6 to 9, wherein the first list index and the second list index indicate motion information of the current block, comprising:

11. An image decoding apparatus, characterized in that the image decoding apparatus comprises:

a memory for storing video data in the form of a code stream;

the video decoder is used for analyzing the code stream to obtain the prediction mode information, the first list index, the second list index and the parameters of the first division mode of the current image block;

12. An image encoding apparatus, characterized in that the image encoding apparatus comprises:

the video encoder is used for obtaining the prediction mode information, the first list index, the second list index and the parameters of the first division mode of the current image block;

13. A terminal, the terminal comprising: one or more processors, memory, and communication interfaces;

the memory, the communication interface, and the one or more processors are connected; the terminal communicates with other devices via the communication interface, the memory for storing computer program code comprising instructions which, when executed by the one or more processors, perform the decoding method of any of claims 6-10 or the encoding method of any of claims 1-5.

14. A storage medium, characterized in that the storage medium comprises a code stream generated by the method according to any one of claims 1-5.

15. A video decoder comprising a non-volatile storage medium and a central processor, wherein the non-volatile storage medium stores an executable program, the central processor being connected to the non-volatile storage medium, the video decoder performing the decoding method according to any of claims 6-10 when the central processor executes the executable program.