CN112135129B

CN112135129B - Inter-frame prediction method and device

Info

Publication number: CN112135129B
Application number: CN201910600591.9A
Authority: CN
Inventors: 陈焕浜; 杨海涛; 张恋
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-06-25
Filing date: 2019-07-04
Publication date: 2024-06-04
Anticipated expiration: 2039-07-04
Also published as: CN118631997A; CN112135129A; CN118631998A

Abstract

The application provides an inter-frame prediction method and device. The method comprises the following steps: after determining that a fusion mode is used for inter-prediction on a current image block, determining whether the current image block allows each fusion mode in K alternative fusion modes to be used; under the condition that the current image block allows a current fusion mode to be used and the current image block allows fusion modes except the current fusion mode to be used in the K alternative fusion modes, analyzing and obtaining a value of a first identifier of the current fusion mode from a code stream; and under the condition that the value of the first identifier indicates that the fusion mode of the current image block for inter-frame prediction is the current fusion mode, inter-frame prediction is carried out on the current image block by using the current fusion mode so as to obtain a prediction block of the current image block. In the application, the analysis redundancy of the fusion syntax element is removed, the decoding complexity is reduced to a certain extent, and the decoding efficiency is improved.

Description

Inter-frame prediction method and device

Technical Field

The present application relates to the field of video image processing technologies, and in particular, to an inter-frame 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 (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 (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 partitioned 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.

Currently, the fusion (merge) technique is an inter-frame prediction technique, and by constructing a candidate motion vector list, motion information with the minimum rate-distortion (RD) cost in the list is determined as a motion vector predictor (motion vector predictor, MVP) of a current block. If the current image block uses a fusion technique for inter prediction, a fusion mode needs to be selected to obtain inter prediction parameters to perform inter prediction on the current image block, and the fusion mode may include: a conventional fusion mode, a fusion motion vector difference (MERGE WITH motion vector difference, MMVD) mode, a sub-block fusion mode (SBMM), a joint intra and inter prediction mode (CIIP), a delta prediction unit mode (triangle prediction unit mode, TPM). In the syntax parsing process of the fusion data (MERGE DATA), it is necessary to sequentially determine which fusion mode or modes will be used to perform inter prediction on the current image block, so that parsing redundancy exists, resulting in higher decoding complexity and lower decoding efficiency in some cases.

Disclosure of Invention

The application provides an inter-frame prediction method and device, which can reduce decoding complexity to a certain extent and improve decoding efficiency.

In a first aspect, the present application provides an inter prediction method, which can be applied to a video decoder. The method may include: after determining that the current image block uses the fusion mode to carry out inter prediction, determining whether the current image block allows each fusion mode in K alternative fusion modes, wherein K is a positive integer greater than or equal to 2; under the condition that the current image block allows the current fusion mode to be used and the current image block allows the fusion modes except the current fusion mode to be used in the K alternative fusion modes, analyzing and obtaining a value of a first identifier of the current fusion mode from the code stream; and under the condition that the value of the first identifier indicates that the fusion mode of the current image block for inter-frame prediction is the current fusion mode, inter-frame prediction is carried out on the current image block by using the current fusion mode so as to obtain a prediction block of the current image block.

In the present application, the second identifier is used to indicate whether the current image block uses the corresponding fusion mode. The first identification may include, but is not limited to: one or more of the identifiers of the regular_merge_flag, the mmvd_merge_flag, the merge_ subblock _flag, the ciip_flag, the merge_triange_flag and the like.

Wherein, the merge_triple_flag may be MERGETRIANGLEFLAG.

In the application, on the premise that the decoder determines that the current image block uses the fusion mode to carry out inter prediction, if the current image block allows the current fusion mode to be used and the current image block allows the fusion mode except the current fusion mode to be used in K alternative fusion modes, the decoder carries out inter prediction on the current image block by using the current fusion mode according to the indication of the value of the first identification of the current image block obtained by analysis in the code stream, so as to obtain the prediction block of the current image block without analyzing the value of the first identification of each fusion mode except the current fusion mode in the K alternative fusion modes, thereby eliminating the analysis redundancy of fusion grammar elements, reducing the complexity of decoding to a certain extent and improving the decoding efficiency.

Based on the first aspect, in some possible embodiments, the method further comprises: and under the condition that the current image block does not allow the K alternative fusion modes to be used in fusion modes other than the current fusion mode, inter-frame prediction is carried out on the current image block by using the current fusion mode so as to obtain a prediction block of the current image block.

Based on the first aspect, in some possible implementations, determining whether the current image block allows use of each of the K alternative fusion modes includes: obtaining a prediction parameter corresponding to a current image block; determining whether the current image block allows each fusion mode to be used according to the prediction parameters; wherein the prediction parameters include one or more of: an indication of a syntax element of an upper video processing unit related to the current image block, a size of the current image block, indication information indicating whether the current image block has a residual, a type of the upper video processing unit.

Based on the first aspect, in some possible embodiments, the superior video processing unit includes a slice in which the current image block is located, a slice group in which the current image block is located, an image in which the current image block is located, or a video sequence in which the current image block is located.

Based on the first aspect, in some possible implementations, in a case that the current image block allows the current fusion mode to be used, and the current image block allows the fusion modes other than the current fusion mode to be used, parsing the value of the first identifier of the current fusion mode from the code stream includes: under the condition that the current image block allows at least one of MMVD modes, SBMM, CIIP modes and TPM to be used, analyzing and obtaining the value of the regular_merge_flag of the traditional fusion mode from the code stream; wherein, the regular_merge_flag is the first identifier of the conventional fusion mode.

Based on the first aspect, in some possible implementations, in a case that the current image block allows the current fusion mode to be used, and the current image block allows the fusion modes other than the current fusion mode to be used, parsing the value of the first identifier of the current fusion mode from the code stream includes: in the case that the current image block allows to use MMVD modes and the current image block allows to use at least one of SBMM, CIIP mode and TPM, resolving and obtaining a mmvd _merge_flag value of MMVD mode from the code stream; wherein mmvd _merge_flag is the first identification of MMVD mode.

Based on the first aspect, in some possible implementations, in a case that the current image block allows the current fusion mode to be used, and the current image block allows the fusion modes other than the current fusion mode to be used, parsing the value of the first identifier of the current fusion mode from the code stream includes: in the case that the current image block allows to use SBMM modes and the current image block allows to use CIIP modes and/or TPM, resolving and obtaining the value of the merge_ subblock _flag of SBMM from the code stream; wherein, merge_ subblock _flag is the first sign of SBMM.

Based on the first aspect, in some possible implementations, in a case that the current image block allows the current fusion mode to be used, and the current image block allows the fusion modes other than the current fusion mode to be used, parsing the value of the first identifier of the current fusion mode from the code stream includes: under the condition that the current image block allows to use CIIP modes and TPM, analyzing and obtaining a ciip _flag value of the CIIP mode from the code stream; wherein ciip _flag is the first identification of CIIP mode.

Based on the first aspect, in some possible embodiments, the method further comprises: when the current image block does not allow the current fusion mode to be used or the current image block does not allow the fusion modes except the current fusion mode to be used in the K alternative fusion modes, the value of the first identification of the current fusion mode is obtained through deduction.

Based on the first aspect, in some possible embodiments, the method further comprises: when the value of the first identifier of the current fusion mode cannot be obtained from the code stream in a parsing mode, the value of the first identifier of the current fusion mode is obtained through deduction.

Based on the first aspect, in some possible embodiments, the current fusion mode is a conventional fusion mode, and deriving the value of the first identifier of the current fusion mode includes: setting general_merge_flag to the value of regular_merge_flag; or setting the value of the regular_merge_flag to a first value; the general_merge_flag is used for indicating whether the inter prediction parameter of the current image block is obtained by the adjacent inter prediction block, and the regular_merge_flag is the first identification of the conventional fusion mode.

Based on the first aspect, in some possible embodiments, the current fusion mode is MMVD modes, and the value of the first identifier mmvd _merge_flag of the MMVD mode is set to a first value if the first derivation condition is satisfied; wherein the first derivation condition includes: the current image block allows MMVD modes to be used.

Based on the first aspect, in some possible embodiments, the current fusion mode is SBMM, and deriving the value of the first identifier of the current fusion mode includes: setting a value of a first flag merge_ subblock _flag of SBMM to a first value in the case that the second derivation condition is satisfied; wherein the second derivation conditions include: the current image block is allowed to use SBMM.

Based on the first aspect, in some possible embodiments, the current fusion mode is CIIP modes, and deriving the value of the first identifier of the current fusion mode includes: setting a value of a first flag ciip _flag of CIIP modes to a first value if a third derivation condition is satisfied; wherein the third derivation condition includes: the current image block allows CIIP modes to be used.

Based on the first aspect, in some possible implementations, the current fusing mode is a TPM, and deriving the value of the first identifier of the current fusing mode includes: setting a value of a first identification merge_triple_flag of the TPM to a first value in the case that the fourth derivation condition is satisfied; wherein the fourth derivation condition comprises: the current image block allows the use of a TPM.

Wherein, the merge_triple_flag may be MERGETRIANGLEFLAG.

Based on the first aspect, in some possible embodiments, the K alternative fusion patterns include a plurality of: conventional converged mode, MMVD mode, SBMM, CIIP mode, TPM.

In a second aspect, the present application provides an inter prediction apparatus that can be applied to a video decoder. The apparatus may include: the determining module is used for determining whether the current image block allows to use each fusion mode in K alternative fusion modes after determining that the fusion mode is used for inter-frame prediction on the current image block, wherein K is a positive integer greater than or equal to 2; the analysis module is used for analyzing and obtaining a value of a first identifier of the current fusion mode from the code stream under the condition that the current image block allows the current fusion mode to be used and the current image block allows fusion modes except the current fusion mode to be used in the K alternative fusion modes; and the prediction module is used for carrying out inter-frame prediction on the current image block by using the current fusion mode under the condition that the value of the first identifier indicates that the fusion mode of the current image block for inter-frame prediction is the current fusion mode so as to obtain a prediction block of the current image block.

Based on the second aspect, in some possible embodiments, the prediction module is further configured to, in a case where the current image block does not allow use of fusion modes of K candidate fusion modes other than the current fusion mode, perform inter-prediction on the current image block using the current fusion mode to obtain a prediction block of the current image block.

Based on the second aspect, in some possible implementation manners, the determining module is configured to obtain a prediction parameter corresponding to the current image block; determining whether the current image block allows each fusion mode to be used according to the prediction parameters; wherein the prediction parameters include one or more of: an indication of a syntax element of an upper video processing unit related to the current image block, a size of the current image block, indication information indicating whether the current image block has a residual, a type of the upper video processing unit.

Based on the second aspect, in some possible embodiments, the superior video processing unit includes a slice in which the current image block is located, a slice group in which the current image block is located, an image in which the current image block is located, or a video sequence in which the current image block is located.

Based on the second aspect, in some possible embodiments, the parsing module is configured to parse and obtain a value of a regular_merge_flag of a conventional fusion mode from the code stream in a case that the current image block allows at least one of MMVD modes, SBMM, CIIP modes, and TPM to be used; wherein, the regular_merge_flag is the first identifier of the conventional fusion mode.

Based on the second aspect, in some possible implementations, the parsing module is configured to parse and obtain a value of mmvd _merge_flag of MMVD mode from the code stream in a case that the current image block allows use of MMVD modes and the current image block allows use of at least one of SBMM, CIIP mode, and TPM; wherein mmvd _merge_flag is the first identification of MMVD mode.

Based on the second aspect, in some possible embodiments, the parsing module is configured to parse and obtain a value of a merge_ subblock _flag of SBMM from the code stream in a case that the current image block allows use of SBMM modes and the current image block allows use of CIIP modes and/or the TPM; wherein, merge_ subblock _flag is the first sign of SBMM.

Based on the second aspect, in some possible embodiments, the parsing module is configured to parse and obtain a value of ciip _flag of CIIP mode from the code stream if the current image block allows use of CIIP mode and TPM; wherein ciip _flag is the first identification of CIIP mode.

Based on the second aspect, in some possible embodiments, the apparatus further comprises: and the deriving module is used for deriving a value of a first identifier of the current fusion mode when the current image block does not allow the current fusion mode to be used or the current image block does not allow the fusion modes except the current fusion mode to be used in the K alternative fusion modes.

Based on the second aspect, in some possible embodiments, the apparatus further comprises: and the deduction module is used for deducting the value of the first identifier of the current fusion mode when the value of the first identifier of the current fusion mode cannot be obtained from the code stream in a resolving mode.

Based on the second aspect, in some possible embodiments, the current fusion mode is a conventional fusion mode, and the deriving module is configured to set the general_merge_flag to a value of the regular_merge_flag; or setting the value of the regular_merge_flag to a first value; the general_merge_flag is used for indicating whether the inter prediction parameter of the current image block is obtained by the adjacent inter prediction block, and the regular_merge_flag is the first identification of the conventional fusion mode.

Based on the second aspect, in some possible embodiments, the current fusion mode is MMVD modes, and the deriving module is configured to set a value of a first identifier mmvd _merge_flag of the MMVD modes to a first value if the first deriving condition is satisfied; wherein the first derivation condition includes: the current image block allows MMVD modes to be used.

Based on the second aspect, in some possible embodiments, when the current fusion mode is SBMM, a deriving module is configured to set a value of a first flag merge_ subblock _flag of SBMM to a first value if a second deriving condition is satisfied; wherein the second derivation conditions include: the current image block is allowed to use SBMM.

Based on the second aspect, in some possible embodiments, the current fusion mode is CIIP modes, and the deriving module is configured to set a value of a first flag ciip _flag of the CIIP mode to a first value if a third deriving condition is satisfied; wherein the third derivation condition includes: the current image block allows CIIP modes to be used.

Based on the second aspect, in some possible embodiments, the current fusion mode is a TPM mode, and the deriving module is configured to set a value of a first identifier merge_triple_flag of the TPM to a first value if a fourth deriving condition is satisfied; wherein the fourth derivation condition comprises: the current image block allows the use of a TPM.

Based on the second aspect, in some possible embodiments, the K alternative fusion patterns include a plurality of: conventional converged mode, MMVD mode, SBMM, CIIP mode, TPM.

In a third aspect, the present application provides a video decoder for decoding image blocks from a bitstream, comprising: the entropy decoding module is used for decoding an index identifier from the code stream, wherein the index identifier is used for indicating target candidate motion information of the current decoded image block; the inter-frame prediction apparatus according to any one of the second aspect, wherein the inter-frame prediction apparatus is configured to predict motion information of a current decoded image block based on target candidate motion information indicated by the index identification, and determine a predicted pixel value of the current decoded image block based on the motion information of the current decoded image block; a reconstruction module for reconstructing a current decoded image block based on the predicted pixel values.

In a fourth aspect, the present application provides an apparatus for decoding video data, the apparatus comprising: a memory for storing video data in the form of a code stream; and the video decoder is used for decoding the video data from the code stream.

In a fifth aspect, the present application provides a decoding 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 any of the methods of the first aspect.

In a sixth aspect, the present application provides a computer readable storage medium storing program code, wherein the program code comprises instructions for performing part or all of the steps of any one of the methods of the first aspect.

In a seventh aspect, the present application provides a computer program product for causing a computer to perform part or all of the steps of any one of the methods of the first aspect when the computer program product is run on the computer.

It should be understood that the second to seventh aspects of the present application are consistent with the technical solutions of the first aspect of the present application, and the advantages obtained by each aspect and the corresponding possible embodiments are similar, and are not repeated.

Drawings

In order to more clearly describe the embodiments of the present application or the technical solutions in the background art, the following description will describe the drawings that are required to be used in the embodiments of the present application or the background art.

FIG. 1A is a block diagram of an example of a video encoding and decoding system 10 for implementing an embodiment of the application;

FIG. 1B is a block diagram of an example of a video coding system 40 for implementing an embodiment of the application;

FIG. 2 is a block diagram of an example structure of an encoder 20 for implementing an embodiment of the present application;

FIG. 3 is a block diagram of an example architecture of a decoder 30 for implementing an embodiment of the present application;

Fig. 4 is a block diagram of an example of a video coding apparatus 400 for implementing an embodiment of the application;

FIG. 5 is a block diagram of another example encoding or decoding device for implementing an embodiment of the present application;

FIG. 6 is a schematic diagram of the current image block in the spatial and temporal domains according to an embodiment of the present application;

FIG. 7A is a diagram illustrating MMVD search points in an embodiment of the present application;

FIG. 7B is a diagram illustrating a MMVD search process in an embodiment of the present application;

FIG. 8 is a schematic diagram illustrating the partitioning of a current image block according to an embodiment of the present application;

FIG. 9 is a flowchart illustrating an inter prediction method according to an embodiment of the present application;

FIG. 10 is a second flowchart illustrating an inter prediction method according to an embodiment of the present application;

fig. 11 is a schematic structural diagram of an inter prediction apparatus according to an embodiment of the present application.

Detailed Description

Embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application. In the following description, reference is made to the accompanying drawings which form a part hereof and which show by way of illustration specific aspects in which embodiments of the application may be practiced. It is to be understood that embodiments of the application may be used in other aspects and may include structural or logical changes not depicted in the drawings. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present application is defined by the appended claims. For example, it should be understood that the disclosure in connection with the described methods may be equally applicable to a corresponding apparatus or system for performing the methods, and vice versa. For example, if one or more specific method steps are described, the corresponding apparatus may comprise one or more units, such as functional units, to perform the one or more described method steps (e.g., one unit performing one or more steps, or multiple units each performing one or more of the multiple steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, if a specific apparatus is described based on one or more units such as a functional unit, for example, the corresponding method may include one step to perform the functionality of the one or more units (e.g., one step to perform the functionality of the one or more units, or multiple steps each to perform the functionality of one or more units, even if such one or more steps are not explicitly described or illustrated in the figures). Further, it is to be understood that features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless explicitly stated otherwise.

The technical scheme related to the embodiment of the application can be applied to the existing video coding standards (such as H.264, HEVC and the like) and future video coding standards (such as H.266). The terminology used in the description of the embodiments of the application herein is for the purpose of describing particular embodiments of the application only and is not intended to be limiting of the application. Some concepts that may be related to embodiments of the present application are briefly described below.

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 herein 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 required to represent the video picture, thereby more efficiently storing and/or transmitting. 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 picture "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).

A video sequence comprises a series of pictures (pictures) which are further divided into slices (slices) which are further divided into blocks (blocks). Video coding performs coding processing in units of blocks, and in some new video coding standards, the concept of blocks is further extended. For example, in the h.264 standard, there are Macro Blocks (MBs), which can be further divided into a plurality of prediction blocks (partition) that can be used for predictive coding. In the high performance video coding (HEVC) standard, basic concepts such as a Coding Unit (CU), a Prediction Unit (PU), and a Transform Unit (TU) are used, and various block units are functionally divided and described by using a completely new tree-based structure. For example, the video coding standard divides a frame of image into Coding Tree Units (CTUs) that do not overlap with each other, and divides a CTU into a plurality of sub-nodes, where the sub-nodes may be divided into smaller sub-nodes according to a Quadtree (QT), and the smaller sub-nodes may be further divided, so as to form a quadtree structure. If the nodes are no longer partitioned, they are called CUs. A CU is a basic unit that divides and encodes an encoded image. Similar tree structures exist for PUs and TUs, which may correspond to prediction blocks, being the basic unit of predictive coding. The CU is further divided into a plurality of PUs according to a division pattern. The TU may correspond to a transform block, which is a basic unit for transforming a prediction residual. However, whether CU, PU or TU, essentially belongs to the concept of blocks (or picture blocks).

In HEVC, for example, CTUs are split into multiple CUs by using a quadtree structure denoted as 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 techniques, the frames are partitioned using quadtrees and binary trees (Quad-tree and binary tree, QTBT) to partition the encoded blocks. In the QTBT block structure, the CU may be square or rectangular in shape.

Herein, for convenience of description and understanding, an image block to be encoded in a current encoded image may be referred to as a current block, for example, in encoding, a block currently being encoded; in decoding, a block currently being decoded is referred to. A decoded image block in a reference image used for predicting a current block is referred to as a reference block, i.e. a reference block is a block providing a reference signal for the current block, wherein the reference signal represents pixel values within the image block. A block in the reference picture that provides a prediction signal for the current block may be referred to as a prediction block, where the prediction signal represents pixel values or sample signals within the prediction block. For example, after traversing multiple reference blocks, the best reference block is found, which will provide prediction for the current block, which is referred to as the prediction block.

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 image 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.

The system architecture to which the embodiments of the present application are applied is described below. Referring to fig. 1A, fig. 1A schematically illustrates a block diagram of a video encoding and decoding system 10 to which embodiments of the present application are applied. As shown in fig. 1A, video encoding and decoding system 10 may include a source device 12 and a destination device 14, source device 12 generating encoded video data, and thus source device 12 may be referred to as a video encoding apparatus. Destination device 14 may decode encoded video data generated by source device 12, and thus destination device 14 may be referred to as a video decoding apparatus. Various implementations of source apparatus 12, destination apparatus 14, or both may include one or more processors and memory coupled to the one or more processors. The memory may include, but is not limited to RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store the desired program code in the form of instructions or data structures accessible by a computer, as described herein. The source device 12 and the destination device 14 may include a variety of devices including desktop computers, mobile computing devices, notebook (e.g., laptop) computers, tablet computers, set-top boxes, telephone handsets such as so-called "smart" phones, televisions, cameras, display devices, digital media players, video game consoles, vehicle mount computers, wireless communication devices, or the like.

Although fig. 1A 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.

A communication connection may be made between source device 12 and destination device 14 via link 13, and destination device 14 may receive encoded video data from source device 12 via link 13. Link 13 may include one or more media or devices capable of moving encoded video data from source device 12 to destination device 14. In one example, link 13 may include one or more communication media that enable source device 12 to transmit encoded video data directly to destination device 14 in real-time. In this example, source apparatus 12 may modulate the encoded video data according to a communication standard, such as a wireless communication protocol, and may transmit the modulated video data to destination apparatus 14. The one or more communication media may include wireless and/or wired communication media such as a Radio Frequency (RF) spectrum or one or more physical transmission lines. The one or more communication media may form part of a packet-based network, such as a local area network, a wide area network, or a global network (e.g., the internet). The one or more communication media may include routers, switches, base stations, or other equipment that facilitate communication from source apparatus 12 to destination apparatus 14.

Source device 12 includes an encoder 20 and, alternatively, source device 12 may also include a picture source 16, a picture preprocessor 18, and a communication interface 22. In a specific implementation, the encoder 20, the picture source 16, the picture preprocessor 18, and the communication interface 22 may be hardware components in the source device 12 or may be software programs in the source device 12. The descriptions are as follows:

The picture source 16 may include or 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., live (augmented reality, AR) pictures). Picture source 16 may be a camera for capturing pictures or a memory for storing pictures, picture source 16 may also include any type of (internal or external) interface for storing previously captured or generated pictures and/or for capturing or receiving pictures. When picture source 16 is a camera, picture source 16 may be, for example, an integrated camera, either local or integrated in the source device; when picture source 16 is memory, picture source 16 may be local or integrated memory integrated in the source device, for example. When the picture source 16 comprises an interface, the interface may for example be an external interface receiving pictures from an external video source, for example an external picture capturing device, such as a camera, an external memory or an external picture generating device, for example 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.

Wherein a picture can be regarded as a two-dimensional array or matrix of pixel elements. The pixels in the array may also be referred to as sampling points. 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. For example, in RBG format or color space, the picture includes corresponding red, green, and blue sample arrays. In video coding, however, each pixel is typically represented in a luminance/chrominance format or color space, e.g., for a picture in YUV format, comprising a luminance component indicated by Y (which may sometimes be indicated by L) and two chrominance components indicated by U and V. The luminance (luma) component Y represents the luminance or grayscale level intensity (e.g., the same in a grayscale picture), while the two chrominance (chroma) components U and V represent the chrominance or color information components. Accordingly, a picture in YUV format includes a luminance sample array of luminance sample values (Y) and two chrominance sample arrays of chrominance values (U and V). Pictures in RGB format may be converted or transformed into YUV 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. In the embodiment of the present application, the picture transmitted from the picture source 16 to the picture processor may also be referred to as the original picture data 17.

A picture preprocessor 18 for receiving the original picture data 17 and performing preprocessing on the original picture data 17 to obtain a preprocessed picture 19 or preprocessed picture data 19. For example, the preprocessing performed by the picture preprocessor 18 may include truing, color format conversion (e.g., from RGB format to YUV format), toning, or denoising.

Encoder 20 (or video encoder 20) receives pre-processed picture data 19, and processes pre-processed picture data 19 using an associated prediction mode (e.g., a prediction mode in various embodiments herein) to provide encoded picture data 21 (details of the structure of encoder 20 will be described further below based on fig. 2 or fig. 4 or fig. 5). In some embodiments, encoder 20 may be configured to perform various embodiments described below to implement the application of the chroma block prediction method described in the embodiments of the present application on the encoding side.

Communication interface 22 may be used to receive encoded picture data 21 and may transmit encoded picture data 21 over link 13 to destination device 14 or any other device (e.g., memory) for storage or direct reconstruction, which may be any device for decoding or storage. Communication interface 22 may be used, for example, to encapsulate encoded picture data 21 into a suitable format, such as a data packet, for transmission over link 13.

Destination device 14 includes a decoder 30, and alternatively destination device 14 may also include a communication interface 28, a picture post-processor 32, and a display device 34. The descriptions are as follows:

Communication interface 28 may be used to receive encoded picture data 21 from source device 12 or any other source, such as a storage device, such as an encoded picture data storage device. The communication interface 28 may be used to transmit or receive encoded picture data 21 via a link 13 between the source device 12 and the 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. Communication interface 28 may, for example, be used to decapsulate data packets transmitted by communication interface 22 to obtain encoded picture data 21.

Both communication interface 28 and communication interface 22 may be configured as unidirectional communication interfaces or bidirectional communication interfaces and may be used, for example, to send and receive messages to establish connections, to acknowledge and to exchange any other information related to the communication link and/or to the transmission of data, for example, encoded picture data transmissions.

Decoder 30 (or referred to as decoder 30) for receiving encoded picture data 21 and providing decoded picture data 31 or decoded picture 31 (details of the structure of decoder 30 will be described below further based on fig. 3 or fig. 4 or fig. 5). In some embodiments, decoder 30 may be configured to perform various embodiments described below to implement the application of the chroma block prediction method described in the embodiments of the present application on the decoding side.

A picture post-processor 32 for performing post-processing on the decoded picture data 31 (also referred to as reconstructed slice data) to obtain post-processed picture data 33. The post-processing performed by the picture post-processor 32 may include: color format conversion (e.g., from YUV format to RGB format), toning, truing, or resampling, or any other process, may also be used to transmit post-processed picture data 33 to display device 34.

A display device 34 for receiving the post-processed picture data 33 for displaying pictures 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 (LCD), an 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.

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

Encoder 20 and decoder 30 may each be implemented as any of a variety of suitable circuits, such as, for example, one or more microprocessors, digital Signal Processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), 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.

In some cases, the video encoding and decoding system 10 shown in fig. 1A is merely an example, and the techniques of embodiments of the present application may be applied 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.

Referring to fig. 1B, fig. 1B is an illustration of an example of a video coding system 40 including encoder 20 of fig. 2 and/or decoder 30 of fig. 3, according to an example embodiment. Video coding system 40 may implement a combination of the various techniques of embodiments of the present application. In the illustrated embodiment, video coding system 40 may include an imaging device 41, an encoder 20, a decoder 30 (and/or a video codec implemented via logic circuits 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 in fig. 1B, the imaging device 41, the antenna 42, the processing unit 46, the logic circuit 47, the encoder 20, the decoder 30, the processor 43, the memory 44, and/or the display device 45 can communicate with each other. As discussed, although video coding system 40 is depicted with encoder 20 and decoder 30, in different examples, video coding system 40 may include only encoder 20 or only decoder 30.

In some examples, antenna 42 may be used to transmit or receive an encoded bitstream of video data. Additionally, in some examples, display device 45 may be used to present video data. In some examples, logic 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. Video coding 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, 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 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.

In some examples, 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, decoder 30 implemented by logic circuitry may include an image buffer (implemented by processing unit 43 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 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 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 coding system 40 may also include a decoder 30 coupled to antenna 42 and used to decode the encoded bitstream. The display device 45 is used to present video frames.

It should be understood that decoder 30 may be used to perform the reverse process for the example described with reference to encoder 20 in embodiments of the present application. Regarding signalling prediction parameters, the decoder 30 may be arranged to receive and parse such prediction parameters and decode the relevant video data accordingly. In some examples, encoder 20 may entropy encode the prediction parameters into an encoded video bitstream. In such examples, decoder 30 may parse such prediction parameters and decode the relevant video data accordingly.

It should be noted that, the optimization processing method for merging motion vector difference techniques described in the embodiments of the present application is mainly used in an inter-frame prediction process, where the process exists in both the encoder 20 and the decoder 30, and the encoder 20 and the decoder 30 in the embodiments of the present application may be, for example, an encoder/decoder corresponding to a video standard protocol such as h.263, h.264, HEVV, MPEG-2, MPEG-4, VP8, VP9, or a next-generation video standard protocol (such as h.266).

Referring to fig. 2, fig. 2 shows a schematic/conceptual block diagram of an example of an encoder 20 for implementing an embodiment of the application. In the example of fig. 2, encoder 20 includes a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a buffer 216, a loop filter unit 220, a decoded picture buffer (decoded picture buffer, DPB) 230, a prediction processing unit 260, and an entropy encoding unit 270. The prediction processing unit 260 may include an inter prediction unit 244, an intra prediction unit 254, and a mode selection unit 262. The inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown). The encoder 20 shown in fig. 2 may also be referred to as a hybrid video encoder or a video encoder according to a hybrid video codec.

For example, residual calculation unit 204, transform processing unit 206, quantization unit 208, prediction processing unit 260, and entropy encoding unit 270 form a forward signal path of encoder 20, while, for example, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, buffer 216, loop filter 220, decoded picture buffer (decoded picture buffer, DPB) 230, prediction processing unit 260 form a backward signal path of the encoder, where 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 an image 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. Image block 203 may also be referred to as a current picture block or a picture block to be encoded, and 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 that also includes the current picture).

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. image 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 encoder 20 may be used to perform any combination of the above-described partitioning techniques.

Like picture 201, image block 203 is also or may be considered as a two-dimensional array or matrix of sampling points having sampling values, albeit of smaller size than picture 201. In other words, the image block 203 may comprise, for example, one sampling array (e.g., a luminance array in the case of a black-and-white picture 201) or three sampling arrays (e.g., one luminance array and two chrominance arrays in the case of a color picture) 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 image block 203 defines the size of the image block 203.

The encoder 20 as shown in fig. 2 is used for encoding a picture 201 block by block, for example, performing encoding and prediction for each image block 203.

The residual calculation unit 204 is configured to calculate a residual block 205 based on the picture image 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 image block 203 on a sample-by-sample (pixel-by-pixel) basis to obtain the residual block 205 in a sample domain.

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.

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 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. Or may use a custom quantization table and signal it from the encoder to the decoder in, for example, 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 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 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 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 (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 reconstructed block 215 is reconstructed without in-loop filtering, decoded picture buffer (decoded picture buffer, DPB) 230 is used to store reconstructed block 215.

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

In a possible implementation, the set of inter prediction modes may depend on the available reference pictures (i.e. at least part of the decoded pictures stored in the DBP230 as described above, for example) 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 an 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. the set of inter prediction modes may comprise advanced motion vector (advanced motion vector prediction, AMVP) modes and fusion (merge) modes, for example. In particular implementations, the set of inter prediction modes may include an improved control point-based AMVP mode, and an improved control point-based merge mode, according to embodiments of the present application. In one example, intra-prediction unit 254 may be used to perform any combination of the inter-prediction techniques described below.

In addition to the above prediction modes, embodiments of the present application may also apply skip (skip) modes and/or direct modes.

The prediction processing unit 260 may be further operative to partition the image 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 image 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 image block 203 (current picture image block 203 of 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 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 acquire inter prediction parameters and perform inter prediction based on or using the inter prediction parameters to acquire 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 prediction parameters associated with the block and the video slice for use by decoder 30 in decoding the picture blocks of the video slice.

Specifically, the inter-prediction unit 244 may transmit prediction parameters including inter-prediction parameters (e.g., indication information of an inter-prediction mode selected for current block prediction after traversing a plurality of inter-prediction modes) to the entropy encoding unit 270. In a possible application scenario, if the inter prediction mode is only one, the inter prediction parameter may not be carried in the prediction parameter, and the decoding end 30 may directly use the default prediction mode for decoding. It is appreciated that the inter prediction unit 244 may be used to perform any combination of inter prediction techniques.

The intra prediction unit 254 is used to obtain, for example, 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 intra-prediction techniques.

Specifically, the intra-prediction unit 254 may transmit prediction parameters including intra-prediction parameters (e.g., indication information of an intra-prediction mode selected for current block prediction after traversing a plurality of intra-prediction modes) to the entropy encoding unit 270. In a possible application scenario, if there is only one intra-prediction mode, the intra-prediction parameter may not be carried in the prediction parameters, and the decoding end 30 may directly use the default prediction mode for decoding.

The entropy encoding unit 270 is used to apply an entropy encoding algorithm or scheme (e.g., a variable length coding (variable length coding, VLC) scheme, a context adaptive VLC (context ADAPTIVE VLC, CAVLC) scheme, an arithmetic coding scheme, a context adaptive binary arithmetic coding (context adaptive binary arithmetic coding, CABAC), syntax-based context-based-adaptive binary arithmetic coding, SBAC), probability interval partitioning entropy (probability interval partitioning entropy, PIPE) coding, or other entropy encoding methods or techniques) to single or all of the quantized residual coefficients 209, inter-prediction parameters, intra-prediction parameters, and/or loop filter parameters (or not applied) to obtain encoded picture data 21 that may be output by 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 prediction parameters for 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.

In particular, in embodiments of the present application, encoder 20 may be used to implement the optimization process described in embodiments below for fusing motion vector difference techniques.

It should be appreciated that other structural variations of video encoder 20 may be used to encode the video stream. For example, for some image blocks or image frames, video encoder 20 may directly quantize the residual signal without processing by transform processing unit 206, and accordingly without processing by inverse transform processing unit 212; or for some image blocks or image frames, video encoder 20 does not generate residual data and accordingly does not need to be processed by transform processing unit 206, quantization unit 208, inverse quantization unit 210, and inverse transform processing unit 212; or video encoder 20 may store the reconstructed image block directly as a reference block without processing by filter 220; or the quantization unit 208 and the inverse quantization unit 210 in the video encoder 20 may be combined together. The loop filter 220 is optional, and in the case of lossless compression encoding, the transform processing unit 206, quantization unit 208, inverse quantization unit 210, and inverse transform processing unit 212 are optional. It should be appreciated that inter-prediction unit 244 and intra-prediction unit 254 may be selectively enabled depending on the different application scenarios.

Referring to fig. 3, fig. 3 shows a schematic/conceptual block diagram of an example of a decoder 30 for implementing an embodiment of the application. 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 prediction parameters, 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 prediction parameters (decoded). Entropy decoding unit 304 is further configured to forward inter-prediction parameters, intra-prediction parameters, and/or other prediction parameters to prediction processing unit 360. Video decoder 30 may receive prediction parameters at the video slice 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 prediction parameters 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 prediction parameters, and generate a prediction block for the current video block being decoded using the prediction information. In an example of this disclosure, prediction processing unit 360 uses some of the received prediction parameters 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. In another example of the present disclosure, the prediction parameters received by video decoder 30 from the bitstream include prediction parameters received in one or more of an adaptive parameter set (ADAPTIVE PARAMETER SET, APS), a Sequence Parameter Set (SPS) PARAMETER SET, a picture PARAMETER SET, PPS), or a slice header.

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.

Specifically, in the embodiment of the present application, the decoder 30 is configured to implement the optimization processing method for fusing motion vector difference techniques described in the later embodiments.

It should be appreciated that other structural variations of video decoder 30 may be used to decode the encoded video bitstream. For example, video decoder 30 may generate an output video stream without processing by filter 320; or for some image blocks or image frames, the entropy decoding unit 304 of the video decoder 30 does not decode quantized coefficients, and accordingly does not need to be processed by the inverse quantization unit 310 and the inverse transform processing unit 312. Loop filter 320 is optional; and for the case of lossless compression, the inverse quantization unit 310 and the inverse transform processing unit 312 are optional. It should be appreciated that the inter prediction unit and the intra prediction unit may be selectively enabled according to different application scenarios.

It should be understood that, in the encoder 20 and the decoder 30 according to the embodiments of the present application, the processing result for a certain link may be further processed and then output to a next link, for example, after the links such as interpolation filtering, motion vector derivation or loop filtering, the processing result for the corresponding link may be further processed by performing operations such as Clip or shift.

For example, the motion vector of the control point of the current image block derived from the motion vector of the neighboring affine encoded block, or the motion vector of the sub-block of the current image block derived therefrom, may be further processed, which is not limited in the embodiment of the present application. For example, the range of motion vectors is constrained to be within a certain bit width. Assuming that the bit width of the allowed motion vector is bitDepth, the range of motion vectors is-2 ^bitDepth-1～2^bitDepth-1 -1. If bitDepth is 16, the value range is-32768-32767. If bitDepth is 18, the value range is-131072 ～ 131071. For another example, the values of the motion vectors (e.g., motion vectors MV of four 4 x4 sub-blocks within one 8x8 image block) are constrained such that the maximum difference between the integer parts of the four 4 x4 sub-blocks MV does not exceed N pixels, e.g., does not exceed one pixel.

The constraint can be made within a certain positioning width by the following two ways:

mode 1, the high order overflow of the motion vector is removed:

ux＝(vx+2^bitDepth)％2^bitDepth

vx＝(ux≥2^bitDepth-1)?(ux-2^bitDepth):ux

uy＝(vy+2^bitDepth)％2^bitDepth

vy＝(uy≥2^bitDepth-1)?(uy-2^bitDepth):uy

Wherein vx is a horizontal component of a motion vector of an image block or a sub-block of the image block, vy is a vertical component of a motion vector of an image block or a sub-block of the image block, ux and uy are intermediate values; bitDepth represents bit width.

For example vx has a value of-32769, 32767 by the above formula. Because in the computer the values are stored in the form of binary complements, -32769's binary complements 1,0111,1111,1111,1111 (17 bits), the computer discards the high order bits for the overflow treatment, the vx value is 0111,1111,1111,1111, 32767, consistent with the result obtained by the formula treatment.

Method 2, clipping the motion vector as shown in the following formula:

vx＝Clip3(-2^bitDepth-1,2^bitDepth-1-1,vx)

vy＝Clip3(-2^bitDepth-1,2^bitDepth-1-1,vy)

where vx is the horizontal component of the motion vector of an image block or a sub-block of the image block and vy is the vertical component of the motion vector of an image block or a sub-block of the image block; wherein x, y and z correspond to three input values of MV clamping process Clip3, respectively, the definition of Clip3 is that the value of z is clamped between intervals [ x, y ]:

Referring to fig. 4, fig. 4 is a schematic structural diagram of a video decoding apparatus 400 (e.g., a video encoding apparatus 400 or a video decoding apparatus 400) according to an embodiment of the present application. The video coding apparatus 400 is adapted to implement the embodiments described herein. In one embodiment, video coding device 400 may be a video decoder (e.g., decoder 30 of fig. 1A) or a video encoder (e.g., encoder 20 of fig. 1A). In another embodiment, video coding apparatus 400 may be one or more of the components described above in decoder 30 of fig. 1A or encoder 20 of fig. 1A.

The video coding apparatus 400 includes: an ingress port 410 and a receiving unit (Rx) 420 for receiving data, a processor, logic unit or Central Processing Unit (CPU) 430 for processing data, a transmitter unit (Tx) 440 and an egress port 450 for transmitting data, and a memory 460 for storing data. The video decoding apparatus 400 may further include a photoelectric conversion component and an electro-optical (EO) component coupled to the inlet port 410, the receiver unit 420, the transmitter unit 440, and the outlet port 450 for the outlet or inlet of optical or electrical signals.

The processor 430 is implemented in hardware and software. Processor 430 may be implemented as one or more CPU chips, cores (e.g., multi-core processors), FPGAs, ASICs, and DSPs. Processor 430 is in communication with inlet port 410, receiver unit 420, transmitter unit 440, outlet port 450, and memory 460. The processor 430 includes a coding module 470 (e.g., an encoding module 470 or a decoding module 470). The encoding/decoding module 470 implements embodiments disclosed herein to implement the chroma block prediction methods provided by embodiments of the present application. For example, the encoding/decoding module 470 implements, processes, or provides various encoding operations. Thus, substantial improvements are provided to the functionality of the video coding device 400 by the encoding/decoding module 470 and affect the transition of the video coding device 400 to different states. Or the encoding/decoding module 470 may be implemented in instructions stored in the memory 460 and executed by the processor 430.

Memory 460 includes one or more disks, tape drives, and solid state drives, and may be used as an overflow data storage device for storing programs when selectively executing such programs, as well as storing instructions and data read during program execution. Memory 460 may be volatile and/or nonvolatile and may be Read Only Memory (ROM), random Access Memory (RAM), random access memory (ternary content-addressable memory, TCAM), and/or Static Random Access Memory (SRAM).

Referring to fig. 5, 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. 1A, according to an example embodiment. The apparatus 500 may implement techniques of embodiments of the present application. In other words, fig. 5 is a schematic block diagram of one implementation of an encoding device or decoding device (simply referred to as decoding device 500) of an embodiment of the present application. The decoding device 500 may include, among other things, a processor 510, a memory 530, and a bus system 550. The processor is connected with the memory through the bus system, the memory is used for storing instructions, and the processor is used for executing the instructions stored by the memory. The memory of the decoding device stores program codes, and the processor may call the program codes stored in the memory to perform various video encoding or decoding methods described in the embodiments of the present application. To avoid repetition, a detailed description is not provided herein.

In an embodiment of the present application, the processor 510 may be a central processing unit (central processing unit, abbreviated as "CPU"), and the processor 510 may also be other general purpose processors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), off-the-shelf programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory 530 may include a Read Only Memory (ROM) device or a Random Access Memory (RAM) device. Any other suitable type of storage device may also be used as memory 530. Memory 530 may include code and data 531 accessed by processor 510 using bus 550. The memory 530 may further include an operating system 533 and an application 535, the application 535 including at least one program that allows the processor 510 to perform the video encoding or decoding methods described by embodiments of the present application, and in particular, the optimization processing methods described by embodiments of the present application for fusing motion vector difference techniques. For example, the applications 535 may include applications 1 to N, which further include a video encoding or decoding application (simply referred to as a video coding application) that performs the video encoding or decoding method described in the embodiments of the present application.

The bus system 550 may include a power bus, a control bus, a status signal bus, and the like in addition to a data bus. For clarity of illustration, the various buses are labeled in the figure as bus system 550.

Optionally, the decoding device 500 may also include one or more output devices, such as a display 570. In one example, the display 570 may be a touch sensitive display that incorporates a display with a touch sensitive unit operable to sense touch input. A display 570 may be connected to processor 510 via bus 550.

The following details the scheme of the embodiment of the present application:

in the video codec technique, if the current image block is inter-predicted using a merge (merge) mode, inter-prediction parameters are acquired using one of the following prediction modes: traditional converged mode (regular merge mode), MMVD mode, SBMM, CIIP mode, TPM.

(One), traditional fusion mode

The merge mode is one of techniques capable of effectively improving inter-frame coding efficiency. For the merge mode, the encoding end firstly constructs a candidate motion vector list through the motion information of the coded image blocks adjacent to the current image block in the space domain or the time domain, takes the candidate motion information with the minimum rate distortion Cost (RD Cost) in the candidate motion vector list as a motion vector predicted value (motion vector predictor, MVP) of the current image block, and then transmits an index value (marked as merge index) of the position of the optimal candidate motion information in the candidate motion vector list to the decoding end.

The positions of the adjacent image blocks and the traversing sequence thereof are predefined. The RD Cost can be calculated by the following formula (1), where J represents the RD Cost, SAD is the sum of absolute errors (sum of absolute differences, SAD) between the predicted pixel value obtained after motion estimation using the candidate motion vector predicted value, R represents the code rate, and λ represents the lagrangian multiplier.

J＝SAD+λR (1)

Further, the encoding end can perform motion search in a neighborhood with the MVP as the center to obtain an actual motion vector of the current image block, and then the encoding end transmits a difference (i.e., residual) between the MVP and the actual motion vector to the decoding end.

For example, fig. 6 is a schematic diagram of the spatial domain and the temporal domain of the current image block in the embodiment of the present application, referring to fig. 6, the spatial candidate motion information is from 5 blocks (A0, A1, B0, B1 and B2) spatially adjacent to each other, and if the adjacent image block is not available (i.e. the adjacent image block does not exist, the adjacent image block is not encoded, or the prediction mode adopted by the adjacent image block is not the inter prediction mode), the motion information of the adjacent image block is not added to the candidate motion vector list of the current image block. The time domain candidate motion information of the current image block is obtained by scaling Motion Vectors (MVs) of the image blocks at corresponding positions in the reference frame according to sequence counts (picture order count, POCs) of the reference frame and the current frame, firstly judging whether the image block at the T position in the reference frame is available or not, and if not, selecting the image block at the C position in the reference frame.

The positions of the neighboring blocks and the traversal order thereof in the merge mode are also predefined, and the positions of the neighboring blocks and the traversal order thereof may be different in different merge modes.

(Two), MMVD modes

The MMVD mode utilizes a merge candidate motion vector list, selects one or more candidate motion vectors from the merge candidate motion vector list, and then performs Motion Vector (MV) expansion expression based on the candidate motion vectors. The MV expansion expression comprises an MV starting point, a motion step length and a motion direction.

Wherein the candidate motion vector selected is of a DEFAULT merge TYPE (e.g., MRG TYPE DEFAULT N) using the existing merge candidate motion vector list. The selected candidate motion vector is the starting point of the MV, in other words, the selected candidate motion vector is used to determine the initial position of the MV.

Referring to table 1, the basic candidate index (base candidate IDX) indicates which candidate motion vector in the candidate motion vector list is selected as the optimal candidate motion vector.

TABLE 1

base candidate IDX	0	1	2	3
					N^th MVP	1^st MVP	2^nd MVP	3^rd MVP	4^th MVP

In some possible embodiments, base candidate IDX may not be determined if the number of candidate motion vectors available for selection in the merge candidate motion vector list is 1.

The step size identification (distance IDX) represents offset distance information of the motion vector. The value of the step size indicator represents the distance to offset the initial position (e.g., a preset distance), the preset distance definition being shown in table 2.

TABLE 2

distance IDX	0	1	2	3	4	5	6	7
									Pixel distance	1/4-pel	1/2-pel	1-pel	2-pel	4-pel	8-pel	16-pel	32-pel

The direction identification (direction IDX) represents the direction based on the initial position Motion Vector Difference (MVD). The direction identification may include four cases in total, and is specifically defined as shown in table 3:

TABLE 3 Table 3

direction IDX	00	01	10	11
					x-axis	+	–	N/A	N/A
y-axis	N/A	N/A	+	–

Where 00 represents the right side, 01 represents the left side, 10 represents the upper side, and 11 represents the lower side.

Fig. 7A is a schematic diagram of MMVD search points in an embodiment of the present application, and fig. 7B is a schematic diagram of a MMVD search process in an embodiment of the present application. The process of determining predicted pixel values for the current image block in accordance with MMVD manner includes: MV start points are first determined according to base candidate IDX, such as see the open dots in the center of the L0 reference frame and the L1 reference frame in fig. 7A, that is, the positions pointed by the solid arrows on the L0 reference frame and the L1 reference frame in fig. 7B. Then, it is determined which direction to shift based on the start point of the MV based on the direction IDX, and it is determined which pixels are shifted in the direction indicated by the direction IDX based on the distance IDX. For example, direction idx=00 and distance idx=2, the motion vector shifted by one pixel point in the x-direction is represented as the motion vector of the current image block to predict or obtain the predicted pixel value of the current image block.

(III), SBMM

In inter prediction of HEVC, motion compensation is performed based on the assumption that motion information of all pixels within a current image block is the same, to obtain a predicted value of a pixel of the current image block. However, in the current image block, not all pixels necessarily have the same motion characteristics, so that the prediction of all pixels in the current image block using the same motion information may reduce the accuracy of motion compensation, and further increase the residual information.

To further improve the coding efficiency, in some possible embodiments, the current image block is divided into at least two sub-blocks, and then motion information of each sub-block is derived, and motion compensation is performed according to the motion information of the sub-block, so as to improve the accuracy of prediction, for example, sub-block motion vector prediction (sub-CU based motion vector prediction, SMVP) technology. The SMVP divides the current image block into sub-blocks with the size of m multiplied by n, deduces the motion information of each sub-block, and then utilizes the motion information of each block to carry out motion compensation to obtain the predicted value of the current image block.

In SBMM, based on the SMVP technique, a corresponding sub-block fusion candidate list (sub-block based MERGING CANDIDATE LIST) may be constructed using a corresponding sub-block fusion mode, and corresponding SBMM may include: advanced temporal motion vector prediction (advanced temporal motion vector prediction, ATMVP), spatial temporal motion vector prediction (spatial-temporal motion vector prediction, STMVP), affine model-based prediction modes (including control point motion vector prediction methods using inheritance and/or control point motion vector prediction methods using construction), inter-frame plane prediction modes (PLANAR). Among them, ATMVP is also called sub-block based temporal motion vector prediction (subblock-based temporal motion vector prediction, sbTMVP).

(IV), CIIP modes

In the current image block encoded using the merge mode, an identification (e.g., ciip _flag) is transmitted to indicate whether the current block uses CIIP mode. When CIIP modes are used, intra-prediction blocks are generated from intra-prediction modes selected from an intra-candidate mode list (INTRA CANDIDATE LIST) according to the relevant syntax elements, inter-prediction blocks are generated using a conventional inter-prediction method, and final prediction blocks are generated by combining intra-prediction coding and inter-prediction coding prediction blocks using an adaptive weighting manner.

For a luminance block, the intra candidate mode list is selected from four modes, DC, PLANAR, horizontal (horizontal), and vertical (vertical). The size of the intra candidate mode list is selected according to the shape of the current coding block, and may be 3 or 4. When the width of the current image block is greater than twice the height, the intra candidate mode list does not include the horizontal mode. When the height of the current image block is greater than twice the width, the intra candidate mode list does not include a vertical mode.

In the weighting method of joint intra prediction coding and inter prediction coding, different weighting coefficients are used for different intra prediction modes. Specifically, when the intra prediction encoding uses the DC or the PLANAR mode, or when the current image block length or width is 4 or less, the predicted values obtained by the intra prediction and the inter prediction use the same weight value/weighting coefficient. Otherwise, the weight value/weighting factor may be determined according to the intra prediction mode used by the current image block and/or the position of the prediction samples in the current image block, e.g., variable weighting factors may be taken when intra prediction coding adopts horizontal and vertical modes.

(V) TPM

The triangle prediction unit mode (triangle PU) may also be referred to as a triangle partition mode (triangle partition mode, TPM) or a fused triangle mode, which is referred to as a TPM for convenience of description, and is also applicable to the following.

Fig. 8 is a schematic diagram of partitioning a current image block according to an embodiment of the present application, and referring to fig. 8, the current image block is partitioned into two triangular prediction units, each of which selects a motion vector and a reference frame index from a unidirectional prediction candidate list. One prediction value is then obtained for each of the two triangular prediction units. The pixels included in the hypotenuse region are then adaptively weighted to obtain a predicted value. The entire current block is then transformed and quantized. In addition, it should be noted that the method of the trigonometric prediction unit is generally only applied to skip mode or merge mode. Fig. 8 (1) shows a division manner of upper left and lower right (i.e., division from upper left to lower right), and fig. 8 (2) shows a division manner of upper right and lower left (i.e., division from upper right to lower left).

In practical application, in the process of inter prediction of the current image block by using the merge mode, other merge modes can be used besides the above-mentioned several merge modes to obtain inter prediction parameters, and the embodiment of the application is not limited specifically.

An embodiment of the present application provides an inter prediction method, which may be performed by the video decoder in the above embodiment.

Fig. 9 is a flowchart of an inter prediction method according to an embodiment of the present application, and referring to fig. 9, the method may include:

S901: determining to use a fusion mode to carry out inter prediction on the current image block;

Here, the decoder may parse a syntax element from the bitstream, which may be used to indicate whether inter prediction parameters of the current image block are obtained from neighboring inter prediction blocks, that is, prediction parameters indicating whether inter prediction is performed on the current image block using a fusion mode. Specifically, the syntax element may be general_merge_flag, merge_flag, or the like; then, when the general_merge_flag is a first value (e.g., the general_merge_flag is 1), it indicates that the decoder performs inter prediction on the current image block using the fusion mode; when the general_merge_flag is a second value (e.g., the general_merge_flag is 0), it indicates that the decoder does not use the fusion mode for inter prediction for the current image block.

If the value of the syntax element general_merge_flag is not present or not present in the bitstream, the decoder may also derive the following: if the cu_skip_flag (for indicating whether the current picture block has a residual, i.e., whether the current picture block uses skip mode) is a first value (e.g., the cu_skip_flag is 1), the general_merge_flag is a first value, whereas the cu_skip_flag is a second value (e.g., the cu_skip_flag is 0), and the general_merge_flag is a second value. The cu_skip_flag is a first value, which indicates that the current image block uses the skip mode, whereas the cu_skip_flag is a second value, which indicates that the current image block does not use the skip mode.

Then, the decoder may determine whether to inter-predict the current picture block using the fusion mode according to a value of a syntax element (e.g., general_merge_flag) parsed from the bitstream or according to a value of a syntax element (e.g., general_merge_flag) derived from the bitstream. The decoder performs S902 after determining to inter-predict the current image block using the fusion mode.

In the embodiment of the present application, the current image block is an image block at CU level, i.e., one image block is one CU.

S902: determining whether the current image block allows use of each of the K alternative fusion modes;

The decoding end and the encoding end may negotiate in advance or the protocol specifies a fusion mode set (or referred to as a fusion mode list), and the fusion mode set may include a plurality of alternative fusion modes. The K candidate fusion modes may be all fusion modes in the fusion mode set, or may be fusion modes in the fusion mode set, where whether the current image block is allowed to be used is not determined.

Whether the K fusion patterns are part or all of a set of fusion patterns, the K alternative fusion patterns may include one or more of the fusion patterns described above, e.g., the K alternative fusion patterns may include: traditional fusion mode, MMVD mode, SBMM, CIIP mode, TPM; or the K alternative fusion patterns may further include: MMVD mode, SBMM, CIIP mode, TPM. Of course, the K alternative fusion modes may also include other fusion modes, which are not specifically limited in the embodiment of the present application.

Here, the decoder may determine whether the current image block allows use of each of K alternative fusion modes after determining that the current image block is inter-predicted using the fusion modes through S901. In practical application, the decoder may determine each fusion mode sequentially according to the arrangement sequence of each fusion mode, or may determine each fusion mode in parallel, so as to determine the fusion mode allowed to be used by the current image block.

In a specific implementation, S902 may include: obtaining a prediction parameter corresponding to a current image block; determining whether the current image block allows each fusion mode to be used according to the prediction parameters;

First, the decoder may obtain the prediction parameters corresponding to the current image block by parsing from the bitstream or obtaining from the syntax element (i.e., MERGE DATA syntax). In an embodiment of the present application, the above prediction parameters may include, but are not limited to, one or more of the following: an indication of syntax elements of the upper video processing unit, a size of the current image block (i.e., cbWidth, cbHeight), indication information indicating whether the current image block has a residual (i.e., cu_skip_flag), a type of the upper video processing unit.

In the high-level syntax of the existing VVC draft, at present, syntax structures including a sequence level, a picture level, and a slice group (tile group) level and/or a slice (slice) level are mainly included, and the sizes of video processing units corresponding to the respective levels are different, for example, the video processing units of the sequence level include multi-frame pictures, the video processing units of the picture level may be divided into a plurality of tile groups or slices, and the video processing units of the tile group level or slice level may be divided into a plurality of CTUs. In the embodiment of the present application, the superior video processing unit may include a slice, a tile group, a frame of image, or a video sequence. Then, the type of the upper video processing unit may be a picture type, slice type (slice_type), or slice group type (tile group type) of the picture in which the current picture block is located.

In practical applications, the above prediction parameters may include, but are not limited to ：sps_mmvd_enabled_flag、sps_ciip_enabled_flag、sps_triangle_enabled_flag、MaxNumSubblockMergeCand、MaxNumTriangleMergeCand、cbWidth、cbHeight、cu_skip_flag、slice_type and the like.

Wherein the sps_ mmvd _enabled_flag is used to indicate whether the current sequence allows the MMVD mode to be used, herein, it may be understood that the sps_ mmvd _enabled_flag is used to indicate whether the current image block allows the MMVD mode to be used, when the sps_ mmvd _enabled_flag is a first value (e.g., sps_ mmvd _enabled_flag is 1), it may be determined that the current image block allows the MMVD mode to be used, whereas when the sps_ mmvd _enabled_flag is a second value (e.g., sps_ mmvd _enabled_flag is 0), it may be determined that the current image block does not allow the MMVD mode to be used;

Likewise, sps_ ciip _enabled_flag is used to indicate whether the current sequence allows CIIP mode to be used, here, it can be understood that sps_ ciip _enabled_flag is used to indicate whether the current image block allows CIIP mode to be used; when the sps_ ciip _enabled_flag is a first value (e.g., sps_ ciip _enabled_flag is 1), it may be determined that the current picture block is permitted to use the CIIP mode, whereas when the sps_ ciip _enabled_flag is a second value (e.g., sps_ ciip _enabled_flag is 0), it may be determined that the current picture block is not permitted to use the CIIP mode;

The sps_triangle_enabled_flag is used to indicate whether the current sequence allows the TPM mode to be used, which may be understood herein as the sps_triangle_enabled_flag is used to indicate whether the current image block allows the TPM mode to be used, and when the sps_triangle_enabled_flag is a first value (e.g., sps_triangle_enabled_flag is 1), it may be determined that the current image block allows the TPM mode to be used, whereas when the sps_triangle_enabled_flag is a second value (e.g., sps_triangle_enabled_flag is 0), it may be determined that the current image block does not allow the TPM mode to be used; maxNumSubblockMergeCand is used to represent the maximum length of the sub-block fusion candidate list, maxNumMergeCand is used to represent the maximum length of the fusion candidate motion vector list, cbWidth is the width of the current image block, cbHeight is the height of the current image block, and slice_type is used to indicate the image type or slice (slice) type of the current image block.

Then, after obtaining the prediction parameters, the decoder may determine whether the current image block uses the respective fusion modes according to the above prediction parameters.

Specifically, the decoder may obtain, according to the prediction parameter, a value of a second identifier corresponding to each fusion mode, and indicate, with the second identifier, whether the current image block uses the corresponding fusion mode. In an embodiment of the present application, the second identifier may include, but is not limited to: allowMMVD, allowSBMM, allowCIIP, allowTPM, one or more of the following. allowMMVD is the second identification of MMVD mode, allowSBMM is the second identification of SBMM, allowCIIP is the second identification of CIIP mode, and allowTPM is the second identification of TPM. When the second identifier is a first value (such as the first identifier is 1), the decoder determines that the current image block allows the fusion mode corresponding to the second identifier to be used; conversely, when the second flag is a second value (e.g., the first flag is 0), the decoder determines that the current image block is permitted to use the fusion mode corresponding to the second flag. For example, when allowMMVD is 1, the decoder determines that the current image block is allowed to use MMVD mode, when allowMMVD is 0, the decoder determines that the current image block is not allowed to use MMVD mode, and the above other fusion modes can be similar, and will not be repeated here.

In some possible implementations, the decoder may obtain the value of the second identity of each fusion pattern by the following formulas (1) to (4).

allowMMVD ＝ sps_mmvd_enabled_flag (1)

allowSBMM＝MaxNumSubblockMergeCand>0&&cbWidth>＝8

&& cbHeight >＝ 8 (2)

allowCIIP＝sps_ciip_enabled_flag&&！cu_skip_flag&&(cbWidth*cbHeight)>＝64

&&cbWidth<128&&cbHeight<128(3)

allowTPM＝sps_triangle_enabled_flag&&slice_type＝＝B

&& MaxNumTriangleMergeCand >＝ 2 && (cbWidth*cbHeight) >＝ 64 (4)

Of course, in some possible embodiments, the decoder may also obtain the value of the second identifier of each fusion mode according to the prediction parameter in other manners, and embodiments of the present application are not limited in particular.

S903: under the condition that the current image block allows the current fusion mode to be used and the current image block allows the fusion modes except the current fusion mode to be used in the K alternative fusion modes, analyzing and obtaining a value of a first identifier of the current fusion mode from the code stream;

The first identifier is used for indicating whether the current image block uses a corresponding fusion mode. The first identification may include, but is not limited to: one or more of the identifiers of the regular_merge_flag, the mmvd_merge_flag, the merge_ subblock _flag, the ciip_flag, the merge_triange_flag and the like. Wherein, the regular_merge_flag is the first identifier of the conventional fusion mode, mmvd _merge_flag is the first identifier of MMVD mode, merge_ subblock _flag is the first identifier of SBMM, ciip _flag is the first identifier of CIIP, and merge_trie_flag is the first identifier of TPM. Assuming that when the regular_merge_flag is 1, the decoder may determine that the current image block is inter-predicted using the conventional fusion mode, and when the regular_merge_flag is 0, the decoder may determine that the current image block is not inter-predicted using the conventional fusion mode; when mmvd _merge_flag is 1, the decoder may determine that inter prediction is performed on the current image block using MMVD mode, and when mmvd _merge_flag is 0, the decoder may determine that inter prediction is not performed on the current image block using MMVD mode; when merge_ subblock _flag is 1, the decoder may determine that inter prediction is performed on the current image block using SBMM, and when merge_ subblock _flag is 0, the decoder may determine that inter prediction is not performed on the current image block using SBMM; when ciip _flag is 1, the decoder may determine to inter-predict the current image block using CIIP mode, and when ciip _flag is 0, the decoder may determine not to inter-predict the current image block using CIIP mode. Wherein, the merge_triple_flag may be MERGETRIANGLEFLAG.

Here, after determining the fusion mode that the current image block is permitted to use, the decoder parses a value of the first flag of the current fusion mode from the code stream in a case where the current image block is permitted to use the current fusion mode and the current image block is permitted to use a fusion mode other than the current fusion mode among the K alternative fusion modes.

Specifically, S903 may include:

In the first case, in the case that the current image block allows at least one of MMVD mode, SBMM, CIIP mode, and TPM to be used, the value of the regular_merge_flag of the conventional fusion mode is obtained from the code stream by parsing, and at this time, the general_merge_flag defaults to a first value, such as the general_merge_flag defaults to 1; or alternatively

In the second case, in the case that the current image block allows to use MMVD modes and the current image block allows to use at least one of SBMM, CIIP mode and TPM, the value of mmvd _merge_flag of MMVD mode is obtained from the code stream; or alternatively

Third, in the case that the current image block allows to use SBMM modes, and the current image block allows to use CIIP modes and/or TPM, the value of the merge_ subblock _flag of SBMM is obtained from the code stream in a parsing way; or alternatively

Fourth, in case that the current image block allows use of CIIP mode and TPM, the value of ciip _flag of CIIP mode is obtained from the bitstream parsing.

It should be noted that, the decoding module may sequentially determine, according to the order of the K alternative fusion modes, whether to parse the value of the first identifier of the current fusion mode from the code stream. When the value of the first identifier of the previous fusion mode is the second value, that is, the current image block does not use the previous fusion mode, the decoder further judges whether to parse the value of the first identifier of the current fusion mode from the code stream.

Then, the step S903 may further include:

corresponding to the first case, when the general_merge_flag is the first value and the current image block allows at least one of MMVD mode, SBMM, CIIP mode and TPM to be used, the value of the regular_merge_flag of the traditional fusion mode is obtained from the code stream in a parsing mode; or alternatively

Corresponding to the second case, when the regular_merge_flag is the second value, the current image block allows to use MMVD modes, and the current image block allows to use at least one of SBMM, CIIP mode and TPM, the value of mmvd _merge_flag in MMVD modes is obtained from the code stream in a parsing mode; or alternatively

Corresponding to the third case, when the regular_merge_flag is the second value, the mmvd _merge_flag is the second value, the current image block is allowed to use SBMM mode, and the current image block is allowed to use CIIP mode and/or TPM, the value of the merge_ subblock _flag of SBMM is obtained from the code stream in a parsing mode; or alternatively

Corresponding to the fourth case, when the regular_merge_flag is the second value, the mmvd _merge_flag is the second value, and the merge_ subblock _flag is the second value, the current image block is allowed to use CIIP mode and TPM, the ciip _flag value of CIIP mode is obtained from the code stream.

In some possible embodiments, in a case where the decoder indicates with the second identifier whether the current image block uses the corresponding fusion mode, the method may further include, before S903 above: the decoder judges whether the value of the second identifier of the current fusion mode meets the preset analysis condition. And if the value of the second identifier of the current fusion mode does not meet the preset analysis condition, the decoder determines the value of the first identifier of the current fusion mode according to the preset deduction condition.

For example, assume that the order of the individual fusion patterns in the set of fusion patterns may be: traditional fusion mode, MMVD mode, SBMM, CIIP mode, TPM; then the first time period of the first time period,

The current fusion mode is a conventional fusion mode, and the preset parsing conditions corresponding to the first case may include, but are not limited to:

1) At least one of allowMMVD, allowSBMM, allowCIIP, allowTPM is greater than 0;

In some possible embodiments, the preset parsing condition 1) may also be described as: allowMMVD + allowSBMM + allowCIIP + allowTPM >0; or allowMMVD allowSBMM allowCIIP allowTPM.

The current fusion mode is MMVD modes, and the preset analysis conditions corresponding to the second case may include, but are not limited to:

2) The regulation_merge_flag is 0, the allowmvd is more than 0, and at least one of the allowmmm and allowCIIP, allowTPM is more than 0;

In some possible embodiments, the preset parsing condition 2) may also be described as: allowMMVD & allowSBMM + allowCIIP + allowTPM >0; or allowMMVD & (allowSBMM + allowCIIP + allowTPM); or allowMMVD & (allowSBMM | allowCIIP | allowTPM).

It should be noted that, in the case where the current fusion mode is MMVD modes, the conventional fusion mode has been confirmed to be not used, that is, the regular_merge_flag is 0, and at this time, the value of the regular_merge_flag may not be repeatedly determined.

The current fusion mode is SBMM, and the preset parsing conditions corresponding to the third case may include, but are not limited to:

3) The regulation_merge_flag is 0, the mmvd_merge_flag is 0, the allowSBMM is more than 0, and the allowCIIP and/or allowTPM is more than 0;

In some possible embodiments, the preset parsing condition 3) may also be described as: allowSBMM & allowCIIP + allowTPM >0; or allowSBMM & (allowCIIP + allowTPM) >0; or allowSBMM & (allowCIIP || allowTPM).

It should be noted that, in the case where the current fusion mode is SBMM modes, the conventional fusion mode and MMVD modes have been confirmed not to be used, that is, the regular_merge_flag is 0 and the mmvd_merge_flag is 0, at this time, the values of the regular_merge_flag and the mmvd _merge_flag may not be repeatedly determined.

The current fusion mode is CIIP modes, and the preset parsing conditions corresponding to the fourth case may include, but are not limited to:

4) The regulation_merge_flag is 0, the merge_subcarrier_flag is 0, the allowances CIIP is more than 0, and the allowances TPM is more than 0;

In some possible embodiments, the preset parsing condition 4) may also be described as: allowCIIP & allowTPM.

It should be noted that, in the case where the current fusion mode is CIIP modes, the conventional fusion mode, MMVD mode, and SBMM have been confirmed not to be used, that is, the regular_merge_flag is 0, the mmvd_merge_flag is 0, and the merge_subcarrier_flag is 0, at this time, the values of the regular_merge_flag, the mmvd_merge_flag, and the merge_ subblock _flag may not be repeatedly determined.

The above determination process can be specifically referred to as a syntax table as described in table 4 below. That is, when the general_merge_flag is the first value, the bitstream may be parsed according to the syntax structure of merge_data (), thereby obtaining the values of the syntax elements in table 4. Wherein (x 0, y 0) represents the coordinate position of the luminance pixel value of the top left vertex of the current image block relative to the luminance pixel of the top left vertex of the current image block, and the meaning of (x 0, y 0) in the following syntax table is the same, and will not be described in detail.

TABLE 4 Table 4

It should be noted that, the preset analysis conditions 1), 2), 3) and 4) may also be described in other manners, and the embodiment of the present application is not limited specifically.

If the decoder determines through the above process that the value of the second identifier meets the preset analysis condition, the decoder can analyze and obtain the value of the first identifier of the corresponding fusion mode from the code stream. For example, if the values allowMMVD, allowSBMM, allowCIIP and allowTPM satisfy the preset parsing condition 1), the decoder may parse the code stream to obtain the value of the first identifier of the conventional fusion mode, that is: the value of the regular_merge_flag; for another example, if the values allowMMVD, allowSBMM, allowCIIP and allowTPM satisfy the preset parsing condition 2), the decoder may parse the code stream to obtain the value of the first identifier of the MMVD mode, that is: mmvd _merge_flag; it can also be: if the values allowSBMM, allowCIIP and allowTPM meet the preset parsing condition 3), the decoder may parse the code stream to obtain the value of the first identifier of SBMM, that is: the value of merge_ subblock _flag; or if the values allowCIIP and allowTPM meet the preset parsing condition 4), the decoder may parse the code stream to obtain the value of the first identifier of the CIIP mode, that is: ciip _flag.

If the decoder determines through the above process that the value of the second identifier does not meet the preset parsing condition, the decoder may determine the value of the first identifier of each fusion mode according to the preset deriving condition.

Here, the preset derivation conditions are explained below.

In some possible embodiments, when the value of the second identifier of each fusion pattern satisfies the above-mentioned preset parsing condition, the value of the first identifier of each fusion pattern may not exist or not exist in the code stream, so that the decoder cannot parse the code stream to obtain the value of the first identifier of each fusion pattern, and in this case, the decoder may also derive the value of the first identifier of each fusion pattern according to the preset deriving condition. For example, if the preset derivation condition is satisfied, the value of the first flag of the fusion mode is set to the first value, otherwise, the value of the first flag of the fusion mode is set to the second value.

For example, if allowMMVD, allowSBMM, allowCIIP and allowTPM do not satisfy the above-mentioned preset parsing condition 1) or the value of the regular_merge_flag does not exist in the bitstream, then the value of the decoder general_merge_flag is set to the value of the regular_merge_flag, and since the general_merge_flag is the first value (e.g., the general_merge_flag is 1), then the value of the regular_merge_flag is also the first value; or the decoder sets the value of the regular_merge_flag to a first value, i.e., sets the value of the regular_merge_flag to 1, at which point it means that the current image block is inter-predicted using the conventional fusion mode.

Or if allowMMVD, allowSBMM, allowCIIP and allowTPM do not satisfy the above-mentioned preset parsing condition 1) or there is no value of the regular_merge_flag in the bitstream, and when the current image block is mode_inter (the current image block uses INTER prediction), the value of the regular_merge_flag is set to the value of the general_merge_flag. That is, when the CuPredMode is MODE_INTER and the general_merge_flag value is 1, the value of the regular_merge_flag is set to 1, otherwise the value of the regular_merge_flag is set to 0.

Wherein CuPredMode is a prediction MODE identifier of the current image block, and may also be expressed as CuPredMode [ x0] [ y0] in some embodiments, and CuPredMode [ x0] [ y0] is MODE_INTER to indicate that the current image block uses INTER prediction. Coordinates (x 0, y 0) represent the position of the luminance pixel of the upper left vertex of the current image block relative to the luminance pixel of the upper left vertex of the image in which the current image block is located. The following CuPredMode [ x0] [ y0] has the same meaning as described herein, and will not be described again.

If allowMMVD, allowSBMM, allowCIIP and allowTPM do not satisfy the preset parsing condition 2) or if the mmvd _merge_flag value does not exist in the code stream, the decoder sets the mmvd _merge_flag value to the first value if the first derivation condition is satisfied; here, the first push condition may allow use of MMVD modes (i.e., allowMMVD value is a first value), a general_merge_flag value is a first value, and a regular_merge_flag value is a second value for the current image block; for example, allowMMVD has a value of 1, a general_merge_flag has a value of 1, and a regular_merge_flag has a value of 0, mmvd _merge_flag is set to 1, and at this time, it means that the current image block is inter-predicted using MMVD mode. Or the first push condition may also allow use of MMVD modes (i.e., allowMMVD value is the first value), general_merge_flag is the first value, regular_merge_flag is the second value, and the current image block uses inter prediction; for example, allowMMVD has a value of 1, a general_merge_flag has a value of 1, a regular_merge_flag has a value of 0, and CuPredMode has a value of mode_inter, mmvd _merge_flag is set to 1.

If allowSBMM, allowCIIP and allowTPM do not satisfy the above-mentioned preset parsing condition 3) or if there is no value of the merge_ subblock _flag in the bitstream, then the decoder sets the value of the merge_ subblock _flag to the first value if the second derivation condition is satisfied; here, the second derivation condition may be that the current image block is permitted to use SBMM (i.e., allowSBMM has a first value), the general_merge_flag has a first value, the regular_merge_flag has a second value, and the merge_ mmvd _flag has a second value; for example, allowSBMM has a value of 1, a general_merge_flag has a value of 1, a regular_merge_flag has a value of 1, and a merge_ mmvd _flag has a value of 0, then the merge_ subblock _flag is set to 1, and at this time, it indicates that the current image block is inter-predicted using SBMM.

Or the second derivation condition may be that the current image block is allowed to use SBMM (i.e., allowSBMM has a first value), the general_merge_flag has a first value, the regular_merge_flag has a second value, the merge_ mmvd _flag has a second value, and the current image block uses inter prediction; for example allowSBMM has a value of 1, a general_merge_flag has a value of 1, a regular_merge_flag has a value of 1, a merge_ mmvd _flag has a value of 0, and a CuPredMode has a MODE_INTER, then the merge_ subblock _flag is set to 1.

If allowCIIP and allowTPM do not satisfy the above-mentioned preset parsing condition 4) or if there is no ciip _flag value in the bitstream, then the decoder sets the ciip _flag value to the first value if the third derivation condition is satisfied; here, the third derivation condition may allow use of CIIP modes (i.e., allowCIIP is a first value), general_merge_flag is a first value, regular_merge_flag is a second value, mmvd _merge_flag is a second value, and merge_ subblock _flag is a second value for the current image block; for example, allowCIIP has a value of 1, a general_merge_flag has a value of 1, a regular_merge_flag has a value of 0, a merge_ mmvd _flag has a value of 0, and a merge_ subblock _flag has a value of 0, ciip _flag is set to 1, and at this time, it means that the current image block is inter-predicted using CIIP mode.

Or the third derivation condition may also allow use of CIIP modes (i.e., allowCIIP is the first value), general_merge_flag is the first value, regular_merge_flag is the second value, mmvd _merge_flag is the second value, merge_ subblock _flag is the second value, and inter prediction is used for the current image block; for example allowCIIP has a value of 1, a general_merge_flag has a value of 1, a regular_merge_flag has a value of 0, a merge_ mmvd _flag has a value of 0, a merge_ subblock _flag has a value of 0, and a CuPredMode has a value of MODE_INTER, ciip _flag is set to 1.

The value of the merge_trie_flag may be derived, for example, in case that the fourth derivation condition is satisfied, the decoder sets the value of the merge_trie_flag to the first value; here, the fourth derivation condition may be that the current image block is permitted to use the TPM mode (i.e., allowTPM is a first value), the general_merge_flag is a first value, the regular_merge_flag is a second value, the mmvd _merge_flag is a second value, the merge_ subblock _flag is a second value, and the ciip _flag is a second value; for example, allowTPM has a value of 1, a general_merge_flag has a value of 1, a regular_merge_flag has a value of 0, a merge_ mmvd _flag has a value of 0, a merge_ subblock _flag has a value of 0, and a ciip _flag has a value of 0, the merge_trigger_flag is set to 1, and at this time, it means that when the picture type or slice type of the current picture block is B, the current picture block is inter-predicted using the TPM mode.

Or the fourth derivation condition may also allow the current image block to use the TPM mode (i.e., allowTPM is a first value), the general_merge_flag is a first value, the regular_merge_flag is a second value, the mmvd _merge_flag is a second value, the merge_ subblock _flag is a second value, the ciip _flag is a second value, and the current image block uses inter prediction; for example allowTPM has a value of 1, a general_merge_flag has a value of 1, a regular_merge_flag has a value of 0, a merge_ mmvd _flag has a value of 0, a merge_ subblock _flag has a value of 0, a ciip _flag has a value of 0, and a CuPredMode has a value of MODE_INTER, then MERGETRIANGLEFLAG is set to 1.

In practical applications, the decoder may also determine the value of the first identifier of each fusion mode through other preset deduction conditions, which is not limited in particular in the embodiments of the present application.

In summary, the decoder may not be limited to obtain the second identifier, the first identifier, the corresponding preset parsing condition and the preset deriving condition of the first fusion mode respectively as shown in table 5. Table 5 is specifically shown below:

TABLE 5

In summary, the decoder may also and not limited to obtain the second identifier, the first identifier, the corresponding preset parsing condition or the preset deriving condition of the first fusion mode respectively as shown in table 6. Table 6 is specifically shown below:

TABLE 6

In the embodiment of the present application, after S902, the decoder determines whether the current image block allows each fusion mode, and then, in the case that the current image block does not allow the use of fusion modes other than the current fusion mode, inter-prediction is performed on the current image block using the current fusion mode, so as to obtain a prediction block of the current image block.

Here, after determining that the current image block does not allow the use of the fusion modes of the K alternative fusion modes other than the current fusion mode, the decoder does not need to further analyze the value of the first identifier of the current image block, but uses the current fusion mode to perform inter-frame prediction on the current image block so as to obtain a prediction block of the current image block, thereby removing the analysis redundancy of the fusion syntax element, reducing the decoding complexity to a certain extent, and improving the decoding efficiency.

S904: and under the condition that the value of the first identifier indicates that the fusion mode of the current image block for inter-frame prediction is the current fusion mode, inter-frame prediction is carried out on the current image block by using the current fusion mode so as to obtain a prediction block of the current image block.

Here, the decoder may determine whether the current image block uses the current fusion mode according to the value of the first flag after obtaining the value of the first flag of the current fusion mode by parsing or deriving from the code stream through S903. Under the condition that the value of the first identifier indicates that the fusion mode of the current image block for inter-frame prediction is the current fusion mode, the decoder does not need to analyze the values of the first identifiers of other fusion modes in the K alternative fusion modes from the code stream, and the current fusion mode is used for inter-frame prediction of the current image block so as to obtain a prediction block of the current image block, so that analysis redundancy of fusion syntax elements is removed, decoding complexity is reduced to a certain extent, and decoding efficiency is improved.

To this end, the decoder completes the inter prediction process for the current image block.

The above method will be described with specific examples.

It is assumed that the order of the fusion patterns in the set of fusion patterns may be: conventional fusion mode→ MMVD mode→ SBMM → CIIP mode→tpm.

Step 1: the decoder determines whether a fusion mode is used for the current image block.

Specifically, whether the current image block uses the fusion mode may be determined according to the syntax element general_merge_flag of the CU level, that is, the value of general_merge_flag is 1, the current image block uses the fusion mode to perform inter prediction, and then step 2 is performed;

Step 2: the decoder determines whether the current image block uses a conventional fusion mode;

Specifically, whether the current image block uses the conventional fusion mode may be determined according to a value of a syntax element_merge_flag. The value of the regular_merge_flag is 1, which indicates that the current image block performs inter prediction using the conventional fusion mode, and the value of the regular_merge_flag is 0, which indicates that the current image block does not perform inter prediction using the conventional fusion mode.

Further, the value of the regular_merge_flag may be determined by parsing the syntax element as described in the above embodiment, or may be derived. If the above-mentioned preset parsing condition 1) is satisfied, the decoder parses the value of the syntax element, regular_merge_flag, from the bitstream, otherwise, when the value of the syntax element does not exist in the bitstream, the value of the regular_merge_flag defaults to be the same as the value of the general_merge_flag, and when the value of the general_merge_flag is 1, the value of the regular_merge_flag is set to 1.

If the value of the regular_merge_flag is1, the current image block is inter predicted using the conventional fusion mode, otherwise, step 3 is performed.

Step 3: the decoder determines whether the current image block uses MMVD modes;

Specifically, whether the current image block uses MMVD may be determined according to the value of the syntax element mmvd _merge_flag. A value of mmvd _merge_flag of 1 indicates that the current image block uses MMVD mode for inter prediction, and otherwise, when a value of mmvd _merge_flag is 0, indicates that the current image block does not use MMVD mode for inter prediction.

Likewise, the mmvd _merge_flag value may be determined by parsing the syntax element as described in the above embodiments, or may be derived. If the above preset parsing condition 2) is satisfied, the decoder may parse the bitstream to obtain a value of mmvd _merge_flag, otherwise, when the value of the syntax element does not exist in the bitstream, the decoder may derive the syntax element using the following preset derivation condition:

The value mmvd _merge_flag is set to 1 if the preset derivation conditions a) to c) below are all true, otherwise, to 0.

A) allowMMVD has a value of 1;

b) The general_merge_flag value is 1;

c) The regular_merge_flag value is 0.

Or when the value of the syntax element does not exist in the code stream or the preset parsing condition 2) is not satisfied, the following preset deriving conditions may be used for deriving:

The value mmvd _merge_flag is set to 1 if the preset derivation conditions a) to c) and c 2) below are all established, otherwise, to 0.

A) allowMMVD has a value of 1;

b) The general_merge_flag value is 1;

c) The regular_merge_flag value is 0;

c2 CuPredMode [ x0] [ y0] is MODE_INTER.

Wherein CuPredMode [ x0] [ y0] is the prediction mode identification of the current image block. CuPredMode [ x0] [ y0] is MODE_INTER, indicating that the current image block uses INTER prediction. Coordinates (x 0, y 0) represent the position of the luminance pixel of the upper left vertex of the current image block relative to the luminance pixel of the upper left vertex of the image in which the current image block is located.

CuPredMode [ x0] [ y0] is MODE_INTRA indicates that the current image block uses INTRA prediction, and CuPredMode [ x0] [ y0] is MODE_IBC indicates that the current image block uses IBC MODE (INTRA block copy).

If mmvd _merge_flag has a value of 1, the current image block is inter predicted using MMVD mode, otherwise, step 4 is performed.

Step 4: the decoder determines whether the current image block is used SBMM;

Specifically, whether the current image block uses SBMM may be determined according to the value of the syntax element merge_ subblock _flag. The value of merge_ subblock _flag is 1, indicating that the current image block uses SBMM for inter prediction, otherwise, the value of merge_ subblock _flag is 0, indicating that the current image block does not use SBMM for inter prediction.

Likewise, the value of the merge_ subblock _flag may be determined by parsing the syntax element as described in the above embodiments, or may be derived. If the above preset parsing condition 3) is satisfied, the decoder parses the code stream to obtain the value of merge_ subblock _flag, otherwise, when the value of the syntax element does not exist in the code stream, the following preset deriving condition may be used for deriving:

the value of merge_ subblock _flag is set to 1 if the following preset derivation conditions d) to g) are all true, otherwise, to 0.

D) allowSBMM has a value of 1

E) general_merge_flag value of 1

F) The regular_merge_flag value is 0

G) The merge_ mmvd _flag value is 0.

Or when the value of the syntax element does not exist in the code stream or the preset parsing condition 3) is not satisfied, the following preset deriving condition may be used for deriving:

The value of merge_ subblock _flag is set to 1 if the preset derivation conditions d) to g) and g 2) below are both established, otherwise, to 0.

D) allowSBMM has a value of 1

E) general_merge_flag value of 1

F) The regular_merge_flag value is 0

G) The merge_ mmvd _flag value is 0

G2 CuPredMode [ x0] [ y0] is MODE_INTER.

If the value of merge_ subblock _flag is 1, the current image block is inter predicted using SBMM, otherwise, step 5 is performed.

Step 5: the decoder determines whether the current image block is used CIIP;

Specifically, whether the current image block is used CIIP is determined according to the value of the syntax element ciip _flag. The ciip _flag has a value of 1, indicating that the current image block is inter-predicted using CIIP mode, and otherwise, the ciip _flag has a value of 0, indicating that the current image block is not inter-predicted using CIIP mode.

Likewise, the ciip _flag value may be determined by parsing the syntax element as described in the above embodiments, or may be derived. If the preset parsing condition 4) is satisfied, the decoder parses the value of ciip _flag from the bitstream, otherwise, when the value of the syntax element does not exist in the bitstream, the value of ciip _flag is derived according to the following preset derivation condition:

if the preset derivation conditions h) to l) below are all true, the value of ciip _flag is set to 1, otherwise, the value of ciip _flag is set to 0.

H) allowCIIP is 1

I) general_merge_flag of 1

J) The regular_merge_flag is 0

K) Merge_ mmvd _flag is 0

L) merge_ subblock _flag is 0.

Or when the value of the syntax element does not exist in the code stream or the preset parsing condition 4) is not satisfied, the following preset deriving conditions may be used for deriving:

If the preset derivation conditions h) to l) and l 2) below are both met, the value of ciip _flag is set to 1, otherwise, the value of ciip _flag is set to 0.

H) allowCIIP is 1

I) general_merge_flag of 1

J) The regular_merge_flag is 0

K) Merge_ mmvd _flag is 0

L) merge_ subblock _flag is 0

L 2) CuPredMode [ x0] [ y0] is MODE_INTER.

If ciip _flag has a value of 0, the current image block is inter predicted using the TPM.

Or if ciip _flag is 0, optionally, MERGETRIANGLEFLAG is set to 1 and the current image block is inter predicted using the TPM.

Or MERGETRIANGLEFLAG is 1 if the following preset derivation conditions m) to r) are all satisfied, otherwise 0.

M) allowTPM is 1

N) general_merge_flag [ x0] [ y0] is 1

O) regular_merge_flag [ x0] [ y0] is 0

P) mmvd _merge_flag [ x0] [ y0] is 0

Q) merge_ subblock _flag [ x0] [ y0] is 0

R) ciip _flag [ x0] [ y0] is 0

Or MERGETRIANGLEFLAG is 1 if the following preset derivation conditions m) to r) and s) are all satisfied, otherwise 0.

M) allowTPM is 1

N) general_merge_flag [ x0] [ y0] is 1

O) regular_merge_flag [ x0] [ y0] is 0

P) mmvd _merge_flag [ x0] [ y0] is 0

Q) merge_ subblock _flag [ x0] [ y0] is 0

R) ciip _flag [ x0] [ y0] is 0

S) CuPredMode [ x0] [ y0] is MODE_INTER

Further, if the merge_trie_flag value is 1, the decoder may parse the TPM related syntax elements, such as merge_trie_split_dir, merge_trie_idx0, merge_trie_idx1, and the like.

In the embodiment of the application, on the premise that the decoder determines that the current image block uses the fusion mode for inter prediction, if the current image block allows the current fusion mode to be used and the current image block allows the fusion mode except the current fusion mode to be used in the K alternative fusion modes, the decoder uses the current fusion mode for inter prediction on the current image block according to the indication of the value of the first identifier of the current image block obtained by analysis in the code stream, so as to obtain the prediction block of the current image block, and the value of the first identifier of each fusion mode except the current fusion mode in the K alternative fusion modes is not needed to be analyzed, thereby eliminating the analysis redundancy of fusion syntax elements, reducing the complexity of decoding to a certain extent and improving the decoding efficiency.

Based on the foregoing embodiments, embodiments of the present application provide an inter prediction method, which may be performed by the video encoder in the foregoing embodiments.

Fig. 10 is a second flowchart of an inter prediction method according to an embodiment of the present application, and referring to fig. 10, the method may include:

S1001: determining to use a fusion mode to carry out inter prediction on the current image block;

Here, the encoder may determine whether the inter prediction parameter of the current image block is acquired from the neighboring inter prediction block according to the RD Cost, that is, determine whether the inter prediction parameter of the current image block is inter predicted using the fusion mode. If the encoder determines that the current image block uses the fusion mode for inter prediction, the syntax element general_merge_flag is set to a first value (e.g., general_merge_flag is set to 1), whereas if the encoder determines that the current image block does not use the fusion mode for inter prediction, the syntax element general_merge_flag is set to a second value (e.g., general_merge_flag is set to 0), and finally, the encoder carries the value of the general_merge_flag in the bitstream to be transferred to the decoder.

In some possible implementations, the encoder does not need to write the general_merge_flag into the bitstream, at which point the decoder can derive using the following method: if the cu_skip_flag (syntax element for indicating whether the skip mode is used for the current picture block) is a first value, the general_merge_flag is a first value, whereas the cu_skip_flag is a second value, and the general_merge_flag is a second value.

Then, the encoder may perform S1002 after determining to inter-predict the current image block using the fusion mode.

S1002: determining at least one fusion mode which is allowed to be used for the current image block from K alternative fusion modes;

Here, after the encoder determines that the fusion mode is used for the current image block through S1001, the prediction parameters described in the above embodiments may be obtained through pre-stored syntax elements or derived syntax elements, and then the encoder determines whether the current image block allows each of K alternative fusion modes to be used, i.e., obtains a value of a second flag of each fusion mode, according to the prediction parameters, and further determines whether the current image block allows each fusion mode to be used according to the value of the second flag. Specifically, the encoder may obtain the value of the second identifier of the fusion mode through formulas (1) to (4) in the above embodiment, which is not described herein. In practical applications, the encoder may not need to pass the value of the second identifier of each fusion pattern to the decoder, which may be obtained by calculation according to formulas (1) to (4) above.

S1003: determining a target fusion mode from at least one fusion mode;

Here, after determining the fusion mode allowed to be used for the current image block through S1002, the encoder calculates RD costs corresponding to each fusion mode, and selects a fusion mode with the smallest RD Cost as a target fusion mode, where the target fusion mode is a fusion mode that is ultimately used for the current image block. Further, the encoder may set a value of the first identifier of the target fusion pattern, and transmit the value of the first identifier of the target fusion pattern to the decoder. Specifically, the encoder may first determine whether the value of the second identifier of each fusion mode meets a preset analysis condition, and if so, carry the value of the first identifier of the corresponding fusion mode in the code stream according to the syntax table shown in table 4 and transmit the value to the decoder.

In some possible embodiments, after obtaining the values of the second identifiers of the respective fusion modes through S1002, the encoder may determine which fusion modes are allowed to be used for the current image block for inter prediction, and set the values of the first identifiers of the fusion modes allowed to be used. For example, when allowMMVD is a first value, the encoder determines that inter prediction is not allowed for the current image block using MMVD mode, and thus the encoder may set the first flag of MMVD mode, namely mmvd _merge_flag, to the first value, whereas when allowMMVD is a second value, the encoder determines that inter prediction is allowed for the current image block using MMVD mode, and thus the encoder may set the first flag of MMVD mode, namely mmvd _merge_flag, to the second value. And the other fusion modes can be similar, so that the encoder can obtain the value of the first identifier of the fusion mode which is allowed to be used for the current image block, and the encoder can further carry the value of the first identifier of the fusion mode, of which the value of the second identifier meets the preset condition, in the code stream according to the grammar table shown in the table 4 and transmit the value of the first identifier to the decoder.

In a specific implementation process, the encoder may further sequentially set values of the first identifier of the fusion mode that is allowed to be used according to an order of the K alternative fusion modes. For example, the order in which fusion patterns are allowed to be used may be: MMVD mode→ SBMM → CIIP mode, then the encoder may set the first flag of MMVD mode, i.e., mmvd _merge_flag, to the second value, and then set the first flags of SBMM and CIIP modes, i.e., merge_ subblock _flag and ciip _flag, to the first value without further determination. The encoder can obtain the value of the first identifier of the fusion mode allowed to be used for the current image block, and the encoder can transmit the value of the first identifier of the fusion mode with the value of the second identifier meeting the preset condition to the decoder according to the syntax table shown in the table 4.

In the above process, the process of determining whether the value of the second identifier meets the preset parsing condition by the encoder is similar to the process of determining whether the value of the second identifier meets the preset parsing condition by the decoder in the above embodiment, specifically referring to the above embodiment, and details are not repeated herein. And when the value of the second identifier meets the preset analysis condition, the encoder carries the value of the first identifier of the corresponding fusion mode in the code stream and transmits the value to the decoder, so that the decoder can analyze the code stream to obtain the value of the first identifier, otherwise, the encoder does not need to carry the value of the first identifier in the code stream and transmit the value of the first identifier to the decoder.

S1004: and carrying out inter prediction on the current image block by using a target fusion mode to obtain a prediction block of the current image block.

To this end, the encoder completes the inter prediction process for the current image block.

Based on the same inventive concept, an embodiment of the present application provides an inter prediction apparatus, which can be applied to the video decoder described in the above embodiment.

Fig. 11 is a schematic structural diagram of an inter prediction apparatus according to an embodiment of the present application, and referring to fig. 11, the inter prediction apparatus 1100 may include: a determining module 1101, configured to determine, after determining that the current image block uses the fusion mode to perform inter prediction, whether the current image block allows use of each fusion mode of K candidate fusion modes, where K is a positive integer greater than or equal to 2; the parsing module 1102 is configured to parse from the code stream to obtain a value of a first identifier of the current fusion mode when the current image block allows the current fusion mode to be used and the current image block allows the fusion modes other than the current fusion mode to be used in the K alternative fusion modes; the prediction module 1103 is configured to, when the value of the first identifier indicates that the fusion mode of the current image block for inter-prediction is the current fusion mode, perform inter-prediction on the current image block using the current fusion mode to obtain a predicted block of the current image block.

In some possible implementations, the prediction module is further configured to, in a case where the current image block does not allow use of fusion modes of the K candidate fusion modes other than the current fusion mode, perform inter-prediction on the current image block using the current fusion mode to obtain a predicted block of the current image block.

In some possible embodiments, the determining module is configured to obtain a prediction parameter corresponding to the current image block; determining whether the current image block allows each fusion mode to be used according to the prediction parameters; wherein the prediction parameters include one or more of: an indication of a syntax element of an upper video processing unit related to the current image block, a size of the current image block, indication information indicating whether the current image block has a residual, a type of the upper video processing unit.

In some possible embodiments, the superior video processing unit includes a slice in which the current image block is located, a slice group in which the current image block is located, an image in which the current image block is located, or a video sequence in which the current image block is located.

In some possible embodiments, the parsing module is configured to parse and obtain a value of a regular_merge_flag of a conventional fusion mode from the code stream in a case that the current image block allows at least one of MMVD mode, SBMM, CIIP mode, and TPM to be used; wherein, the regular_merge_flag is the first identifier of the conventional fusion mode.

In some possible implementations, the parsing module is configured to parse and obtain a value of mmvd _merge_flag of MMVD mode from the code stream in a case where the current image block allows use of MMVD modes and the current image block allows use of at least one of SBMM, CIIP mode, and TPM; wherein mmvd _merge_flag is the first identification of MMVD mode.

In some possible embodiments, the parsing module is configured to parse the target_ subblock _flag of SBMM from the code stream if the current image block allows use of SBMM modes and the current image block allows use of CIIP modes and/or the TPM; wherein, merge_ subblock _flag is the first sign of SBMM.

In some possible implementations, the parsing module is configured to parse and obtain a value of ciip _flag of CIIP mode from the code stream if the current image block allows use of CIIP modes and the TPM; wherein ciip _flag is the first identification of CIIP mode.

In some possible embodiments, the apparatus further comprises: and the deriving module is used for deriving a value of a first identifier of the current fusion mode when the current image block does not allow the current fusion mode to be used or the current image block does not allow the fusion modes except the current fusion mode to be used in the K alternative fusion modes.

In some possible embodiments, the apparatus further comprises: and the deduction module is used for deducting the value of the first identifier of the current fusion mode when the value of the first identifier of the current fusion mode cannot be obtained from the code stream in a resolving mode.

In some possible embodiments, the current fusion mode is a conventional fusion mode, and the deriving module is configured to set the general_merge_flag to a value of the regular_merge_flag; or setting the value of the regular_merge_flag to a first value; the general_merge_flag is used for indicating whether the inter prediction parameter of the current image block is obtained by the adjacent inter prediction block, and the regular_merge_flag is the first identification of the conventional fusion mode.

In some possible embodiments, the current fusion mode is MMVD modes, and the deriving module is configured to set a value of a first identifier mmvd _merge_flag of the MMVD mode to a first value if the first deriving condition is satisfied; wherein the first derivation condition includes: the current image block allows MMVD modes to be used.

In some possible embodiments, the current fusion mode is SBMM, and the deriving module is configured to set a value of a first flag merge_ subblock _flag of SBMM to a first value if the second deriving condition is satisfied; wherein the second derivation conditions include: the current image block is allowed to use SBMM.

In some possible embodiments, the current fusion mode is CIIP modes, and the deriving module is configured to set a value of a first flag ciip _flag of the CIIP mode to a first value if the third deriving condition is satisfied; wherein the third derivation condition includes: the current image block allows CIIP modes to be used.

In some possible implementations, the current fusion mode is a TPM, and the deriving module is configured to set a value of a first identifier merge_triple_flag of the TPM to a first value if a fourth deriving condition is satisfied; wherein the fourth derivation condition comprises: the current image block allows the use of a TPM.

In some possible embodiments, the K alternative fusion patterns include the following: conventional converged mode, MMVD mode, SBMM, CIIP mode, TPM.

Based on the same inventive concept, an embodiment of the present application provides a video decoder for decoding an image block from a code stream, including: the entropy decoding module is used for decoding an index identifier from the code stream, wherein the index identifier is used for indicating target candidate motion information of the current decoded image block; the inter-frame prediction apparatus according to any one of the second aspect, wherein the inter-frame prediction apparatus is configured to predict motion information of a current decoded image block based on target candidate motion information indicated by the index identification, and determine a predicted pixel value of the current decoded image block based on the motion information of the current decoded image block; a reconstruction module for reconstructing a current decoded image block based on the predicted pixel values.

Based on the same inventive concept, an embodiment of the present application provides an apparatus for decoding video data, the apparatus comprising: a memory for storing video data in the form of a code stream; and the video decoder is used for decoding the video data from the code stream.

Based on the same inventive concept, an embodiment of the present application provides a decoding apparatus including: 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 any of the methods of the first aspect.

Based on the same inventive concept, embodiments of the present application provide a computer-readable storage medium storing program code, wherein the program code includes instructions for performing part or all of the steps of any one of the methods of the first aspect.

Based on the same inventive concept, embodiments of the present application provide a computer program product, which when run on a computer, causes the computer to perform part or all of the steps of any one of the methods of the first aspect.

Those of skill in the art will appreciate that the functions described in connection with the various illustrative logical blocks, modules, and algorithm steps described in connection with the disclosure herein may be implemented as hardware, software, firmware, or any combination thereof. If implemented in software, the functions described by the various illustrative logical blocks, modules, and steps may be stored on a computer readable medium or transmitted as one or more instructions or code and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media corresponding to tangible media, such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another (e.g., according to a communication protocol). In this manner, a computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium, or (2) a communication medium, such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementing the techniques described in this disclosure. The computer program product may include a computer-readable medium.

By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood that the computer-readable storage medium and data storage medium do not include connections, carrier waves, signals, or other transitory media, but are actually directed to non-transitory tangible storage media. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, digital Versatile Disc (DVD), and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The instructions may be executed by one or more processors, such as one or more Digital Signal Processors (DSPs), general purpose microprocessors, application Specific Integrated Circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, the term "processor" as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. Additionally, in some aspects, the functions described by the various illustrative logical blocks, modules, and steps described herein may be provided within dedicated hardware and/or software modules configured for encoding and decoding, or incorporated in a combination codec. Moreover, the techniques may be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including a wireless handset, an Integrated Circuit (IC), or a set of ICs (e.g., a chipset). The various components, modules, or units are described in this disclosure in order to emphasize functional aspects of the devices for performing the disclosed techniques, but do not necessarily require realization by different hardware units. Indeed, as described above, the various units may be combined in a codec hardware unit in combination with suitable software and/or firmware, or provided by an interoperable hardware unit (including one or more processors as described above).

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.

The foregoing is merely illustrative of the embodiments of the present application, and the scope of the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the technical scope of the present application should be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An inter prediction method, comprising:

After determining that the fusion mode is used for inter prediction on the current image block, determining whether the current image block allows each fusion mode in K alternative fusion modes to be used, wherein K is a positive integer greater than or equal to 2;

under the condition that the current image block allows a current fusion mode to be used and the current image block allows fusion modes except the current fusion mode to be used in the K alternative fusion modes, analyzing and obtaining a value of a first identifier of the current fusion mode from a code stream;

And under the condition that the value of the first identifier indicates that the fusion mode of the current image block for inter-frame prediction is the current fusion mode, inter-frame prediction is carried out on the current image block by using the current fusion mode so as to obtain a prediction block of the current image block.

2. The method according to claim 1, wherein the method further comprises:

And under the condition that the current image block does not allow the fusion modes of the K alternative fusion modes except the current fusion mode, inter-frame prediction is carried out on the current image block by using the current fusion mode so as to obtain a prediction block of the current image block.

3. The method of claim 1, wherein the determining whether the current image block allows use of each of K alternative fusion modes comprises:

obtaining a prediction parameter corresponding to the current image block;

Determining whether the current image block allows the use of each fusion mode according to the prediction parameters;

Wherein the prediction parameters include one or more of: an indication of a syntax element of a superior video processing unit associated with the current image block, a size of the current image block, indication information indicating whether the current image block has a residual, a type of the superior video processing unit.

4. A method according to claim 3, wherein the superior video processing unit comprises a slice in which the current image block is located, a slice group in which the current image block is located, an image in which the current image block is located, or a video sequence in which the current image block is located.

5. The method according to any one of claims 1 to 4, wherein, in the case that the current image block allows the use of a current fusion mode and the current image block allows the use of a fusion mode other than the current fusion mode among the K alternative fusion modes, parsing a code stream to obtain a value of a first identifier of the current fusion mode includes:

under the condition that the current image block allows at least one of MMVD modes, SBMM, CIIP modes and TPM to be used, analyzing and obtaining the value of the regular_merge_flag of the traditional fusion mode from the code stream;

Wherein, the regular_merge_flag is the first identifier of the conventional fusion mode.

6. The method according to any one of claims 1 to 4, wherein, in the case that the current image block allows the use of a current fusion mode and the current image block allows the use of a fusion mode other than the current fusion mode among the K alternative fusion modes, parsing a code stream to obtain a value of a first identifier of the current fusion mode includes:

in the case that the current image block allows to use MMVD modes and the current image block allows to use at least one of SBMM, CIIP mode and TPM, resolving and obtaining a value of mmvd _merge_flag of the MMVD mode from a code stream;

wherein mmvd _merge_flag is the first identification of MMVD mode.

7. The method according to any one of claims 1 to 4, wherein, in the case that the current image block allows the use of a current fusion mode and the current image block allows the use of a fusion mode other than the current fusion mode among the K alternative fusion modes, parsing a code stream to obtain a value of a first identifier of the current fusion mode includes:

In the case that the current image block allows to use SBMM modes and the current image block allows to use CIIP modes and/or TPM, resolving and obtaining the value of the merge_ subblock _flag of SBMM from a code stream;

Wherein, merge_ subblock _flag is the first sign of SBMM.

8. The method according to any one of claims 1 to 4, wherein, in the case that the current image block allows the use of a current fusion mode and the current image block allows the use of a fusion mode other than the current fusion mode among the K alternative fusion modes, parsing a code stream to obtain a value of a first identifier of the current fusion mode includes:

under the condition that the current image block allows to use CIIP modes and TPM, analyzing and obtaining the ciip _flag value of the CIIP mode from a code stream;

wherein ciip _flag is the first identification of CIIP mode.

9. The method according to any one of claims 1 to 4, further comprising:

when the current image block does not allow the current fusion mode to be used or the current image block does not allow the fusion modes except the current fusion mode to be used in the K alternative fusion modes, the value of the first identification of the current fusion mode is obtained through deduction.

10. The method according to any one of claims 1 to 4, further comprising:

And when the value of the first identifier of the current fusion mode cannot be obtained from the code stream in a parsing way, obtaining the value of the first identifier of the current fusion mode through deduction.

11. The method of claim 10, wherein the current fusion pattern is a legacy fusion pattern, the deriving obtaining the value of the first identification of the current fusion pattern comprises:

setting general_merge_flag to the value of regular_merge_flag; or alternatively

Setting the value of the regular_merge_flag to a first value;

The general_merge_flag is used for indicating whether the inter prediction parameter of the current image block is obtained by the adjacent inter prediction block, and the regular_merge_flag is the first identification of the conventional fusion mode.

12. The method of claim 10, wherein the current fusion pattern is MMVD patterns, the deriving obtaining the value of the first identification of the current fusion pattern comprises:

setting a value of a first flag mmvd _merge_flag of MMVD modes to a first value if a first derivation condition is satisfied;

wherein the first derivation condition includes: the current image block allows MMVD modes to be used.

13. The method of claim 10, wherein the current fusion pattern is SBMM, and wherein deriving the value of the first identification of the current fusion pattern comprises:

Setting a value of a first flag merge_ subblock _flag of SBMM to a first value in the case that the second derivation condition is satisfied;

Wherein the second derivation condition includes: the current image block is allowed to use SBMM.

14. The method of claim 10, wherein the current fusion pattern is CIIP patterns, the deriving obtaining the value of the first identification of the current fusion pattern comprises:

Setting a value of a first flag ciip _flag of CIIP modes to a first value if a third derivation condition is satisfied;

Wherein the third derivation condition includes: the current image block allows CIIP modes to be used.

15. The method of claim 10, wherein the current fusing mode is a TPM, the deriving a value of a first identification of the current fusing mode comprising:

setting a value of a first identification merge_triple_flag of the TPM to a first value in the case that the fourth derivation condition is satisfied;

wherein the fourth derivation condition includes: the current image block allows the use of a TPM.

16. The method of any one of claims 1 to 4, 11 to 15, wherein the K alternative fusion patterns comprise a plurality of: conventional converged mode, MMVD mode, SBMM, CIIP mode, TPM.

17. An inter prediction apparatus, comprising:

The determining module is used for determining whether the current image block allows to use each fusion mode in K alternative fusion modes after determining that the fusion mode is used for inter-frame prediction on the current image block, wherein K is a positive integer greater than or equal to 2;

The analysis module is used for analyzing and obtaining a value of a first identifier of the current fusion mode from a code stream under the condition that the current image block allows the current fusion mode to be used and the current image block allows the fusion modes except the current fusion mode to be used in the K alternative fusion modes;

And the prediction module is used for performing inter-frame prediction on the current image block by using the current fusion mode under the condition that the value of the first identifier indicates that the fusion mode of inter-frame prediction on the current image block is the current fusion mode, so as to obtain a prediction block of the current image block.

18. The apparatus of claim 17, wherein the prediction module is further configured to, in a case where the current image block does not allow use of a fusion mode of the K candidate fusion modes other than the current fusion mode, inter-predict the current image block using the current fusion mode to obtain a prediction block for the current image block.

19. The apparatus of claim 17, wherein the determining module is configured to obtain a prediction parameter corresponding to the current image block; determining whether the current image block allows the use of each fusion mode according to the prediction parameters; wherein the prediction parameters include one or more of: an indication of a syntax element of a superior video processing unit associated with the current image block, a size of the current image block, indication information indicating whether the current image block has a residual, a type of the superior video processing unit.

20. The apparatus of claim 19, wherein the superior video processing unit comprises a slice in which the current image block is located, a slice group in which the current image block is located, an image in which the current image block is located, or a video sequence in which the current image block is located.

21. The apparatus according to any one of claims 17 to 20, wherein the parsing module is configured to parse a value of a regular_merge_flag of a legacy fusion mode from a code stream if the current image block allows at least one of MMVD mode, SBMM, CIIP mode, and TPM to be used; wherein, the regular_merge_flag is the first identifier of the conventional fusion mode.

22. The apparatus according to any one of claims 17 to 20, wherein the parsing module is configured to parse a value of mmvd _merge_flag of the MMVD mode from a code stream if the current image block allows use of MMVD modes and the current image block allows use of at least one of SBMM, CIIP mode, and TPM; wherein mmvd _merge_flag is the first identification of MMVD mode.

23. The apparatus according to any of claims 17 to 20, wherein the parsing module is configured to parse a code stream to obtain a value of the merge_ subblock _flag of SBMM if the current image block allows use of SBMM modes and the current image block allows use of CIIP modes and/or a TPM; wherein, merge_ subblock _flag is the first sign of SBMM.

24. The apparatus according to any one of claims 17 to 20, wherein the parsing module is configured to parse a value of ciip _flag of the CIIP mode from a code stream if the current image block allows use of CIIP modes and a TPM; wherein ciip _flag is the first identification of CIIP mode.

25. The apparatus according to any one of claims 17 to 20, further comprising: and the deriving module is used for deriving a value of a first identifier of the current fusion mode when the current image block does not allow the current fusion mode to be used or the current image block does not allow the fusion modes except the current fusion mode to be used in the K alternative fusion modes.

26. The apparatus according to any one of claims 17 to 20, further comprising: and the deduction module is used for deducting the value of the first identifier of the current fusion mode when the value of the first identifier of the current fusion mode cannot be obtained from the code stream in a resolving mode.

27. The apparatus of claim 25, wherein the current fusion mode is a legacy fusion mode, and wherein the deriving module is configured to set a general_merge_flag to a value of a regular_merge_flag; or setting the value of the regular_merge_flag to a first value; the general_merge_flag is used for indicating whether the inter prediction parameter of the current image block is obtained by the adjacent inter prediction block, and the regular_merge_flag is the first identification of the conventional fusion mode.

28. The apparatus of claim 25, wherein the current fusion mode is a MMVD mode, and wherein the deriving module is configured to set a value of a first flag mmvd _merge_flag of the MMVD mode to a first value if a first deriving condition is satisfied; wherein the first derivation condition includes: the current image block allows MMVD modes to be used.

29. The apparatus of claim 25, wherein the current fusion mode is SBMM, and wherein the deriving module is configured to set a value of a first flag merge_ subblock _flag of SBMM to a first value if a second deriving condition is satisfied; wherein the second derivation condition includes: the current image block is allowed to use SBMM.

30. The apparatus of claim 25, wherein the current fusion mode is a CIIP mode, and wherein the deriving module is configured to set a value of a first flag ciip _flag of the CIIP mode to a first value if a third deriving condition is met; wherein the third derivation condition includes: the current image block allows CIIP modes to be used.

31. The apparatus of claim 25, wherein the current fusion mode is a TPM, and wherein the derivation module is configured to set a value of a first flag, merge_tri_flag, of the TPM to a first value if a fourth derivation condition is satisfied; wherein the fourth derivation condition includes: the current image block allows the use of a TPM.

32. The apparatus of any one of claims 17 to 20, 27 to 31, wherein the K alternative fusion patterns comprise a plurality of: conventional converged mode, MMVD mode, SBMM, CIIP mode, TPM.

33. A video decoder for decoding image blocks from a bitstream, comprising:

the entropy decoding module is used for decoding an index identifier from the code stream, wherein the index identifier is used for indicating target candidate motion information of the current decoded image block;

The inter-prediction apparatus of any one of claims 17 to 32, the inter-prediction apparatus being configured to predict motion information of the current decoded image block based on target candidate motion information indicated by the index identification, determine a predicted pixel value of the current decoded image block based on the motion information of the current decoded image block;

a reconstruction module for reconstructing the current decoded image block based on the predicted pixel values.

34. A video decoding apparatus, comprising: a non-volatile memory and a processor coupled to each other, the processor invoking program code stored in the memory to perform the method as described in any of claims 1 to 16.