Coding method, decoding method, coder, decoder and storage medium

Abstract

Disclosed in the present application are a coding method, a decoding method, a coder, a decoder and a storage medium. No matter at a coding end or a decoding end, the coding / decoding method comprises: according to a first intra-frame prediction mode, determining a first intra-frame prediction value of a target sub-block in a current block; on the basis of a reference sample value of the target sub-block, determining a second intra-frame prediction mode of the target sub-block; according to the second intra-frame prediction mode, determining a second intra-frame prediction value of the target sub-block; and, on the basis of the first intra-frame prediction value and the second intra-frame prediction value, determining an intra-frame prediction value of the target sub-block. Thus, when the current block uses an intra-frame sub-block partition mode, the present application fully utilizes content characteristics of a reconstructed area to adaptively select the second intra-frame prediction mode, and takes into account the first intra-frame prediction mode to perform combined prediction on the sub-blocks, thereby improving prediction accuracy of the intra-frame sub-block partition mode, and further improving coding and decoding performance.

Description

Coding and Decoding Method, Encoder, Decoder, and Storage Medium Technical Field This application relates to the field of video coding and decoding technologies, and particularly to a coding and decoding method, an encoder, a decoder, and a storage medium. Background Art The Intra Sub-Partitions (ISP) technology divides an encoding block into several sub-blocks, so that the reconstructed pixels after encoding the previous sub-block can provide a reference for the next sub-block, and the same intra prediction mode is shared by all sub-blocks. However, in the actual encoding process, the sub-blocks divided from the same encoding block may have different content characteristics. Using the same intra prediction mode for prediction of all sub-blocks will reduce the prediction accuracy and thus affect the encoding efficiency. Summary of the Invention This application provides a coding and decoding method, an encoder, a decoder, and a storage medium, which make full use of the content characteristics of the reconstructed area, adaptively select a second intra prediction mode, and perform a fusion prediction on the sub-blocks in combination with the first intra prediction mode, so as to improve the prediction accuracy of the intra sub-partition mode and further improve the coding and decoding performance. The technical solution of this application can be implemented as follows: In a first aspect, an embodiment of this application provides a decoding method, which is applied to a decoder. The method includes: Decoding a bitstream to determine the prediction parameters of the current block, where the prediction parameters include a first intra prediction mode; Determining a first intra prediction value of a target sub-block in the current block according to the first intra prediction mode; Determining a second intra prediction mode of the target sub-block based on the reference sample values of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; Determining a second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; Determining an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; Determining a reconstructed value of the target sub-block based on the intra prediction value of the target sub-block. In a second aspect, an embodiment of this application provides an encoding method, which is applied to an encoder. The method includes: Determining a first intra prediction mode of the current block; Determining a first intra prediction value of a target sub-block in the current block according to the first intra prediction mode; Determine a second intra prediction mode of the target sub-block based on a reference sample value of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; Determine a second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; Determine an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; Determine a reconstructed value of the target sub-block based on the intra prediction value of the target sub-block; Make an encoding decision based on the reconstructed value of the target sub-block, and determine a prediction parameter of the current block, where the prediction parameter includes the first intra prediction mode; Encode the prediction parameter and write the obtained encoded bits into the bitstream. In a third aspect, an embodiment of the present application provides an encoder, including a first determination unit, a first prediction unit, a decision unit, and an encoding unit; where: The first determination unit is configured to determine a first intra prediction mode of the current block; The first prediction unit is configured to determine a first intra prediction value of a target sub-block in the current block according to the first intra prediction mode; The first determination unit is further configured to determine a second intra prediction mode of the target sub-block based on a reference sample value of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; The first prediction unit is further configured to determine a second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; The first prediction unit is further configured to determine an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; and determine a reconstructed value of the target sub-block based on the intra prediction value of the target sub-block; The decision unit is configured to make an encoding decision based on the reconstructed value of the target sub-block, and determine a prediction parameter of the current block, where the prediction parameter includes the first intra prediction mode; The encoding unit is configured to encode the prediction parameter and write the obtained encoded bits into the bitstream. In a fourth aspect, an embodiment of the present application provides an encoder, including a first memory and a first processor; where: A first memory for storing a computer program that can run on a first processor; A first processor for, when running the computer program, executing the method described in the second aspect. In a fifth aspect, an embodiment of the present application provides a decoder, including a decoding unit, a second determination unit, and a second prediction unit; wherein: The decoding unit is configured to decode a bitstream and determine prediction parameters of a current block, where the prediction parameters include a first intra prediction mode; The second prediction unit is configured to determine a first intra prediction value of a target sub-block in the current block according to the first intra prediction mode; The second determination unit is configured to determine a second intra prediction mode of the target sub-block based on reference sample values of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; The second prediction unit is further configured to determine a second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; The second prediction unit is further configured to determine an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; and determine a reconstruction value of the target sub-block based on the intra prediction value of the target sub-block. In a sixth aspect, an embodiment of the present application provides a decoder, including a second memory and a second processor; wherein: A second memory for storing a computer program that can run on a second processor; A second processor for, when running the computer program, executing the method described in the first aspect. In a seventh aspect, an embodiment of the present application provides a computer-readable storage medium, and the computer-readable storage medium stores a bitstream generated by the encoding method described above. In an eighth aspect, an embodiment of the present application provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program, and when the computer program is executed, it implements the method described in the first aspect or implements the method described in the second aspect. The embodiments of the present application provide an encoding and decoding method, an encoder, a decoder, and a storage medium. Whether at the encoding end or the decoding end, according to the first intra prediction mode, determine the first intra prediction value of the target sub-block in the current block; based on the reference sample value of the target sub-block, determine the second intra prediction mode of the target sub-block; according to the second intra prediction mode, determine the second intra prediction value of the target sub-block; based on the first intra prediction value and the second intra prediction value, determine the intra prediction value of the target sub-block. In this way, when the current block uses the intra sub-block partitioning mode, make full use of the content characteristics of the reconstructed area, adaptively select the second intra prediction mode, and perform fusion prediction on the sub-blocks in combination with the first intra prediction mode, improving the prediction accuracy of the intra sub-block partitioning mode, thereby further improving the encoding and decoding performance. Description of the Drawings FIG. 1 is a schematic block diagram of an encoder provided by an embodiment of the present application; FIG. 2 is a schematic block diagram of a decoder provided by an embodiment of the present application; FIG. 3 is a schematic network architecture diagram of an encoding and decoding system provided by an embodiment of the present application; FIG. 4 is a schematic flowchart of a decoding method provided by an embodiment of the present application; FIG. 5 is a schematic diagram of intra sub-block partitioning provided by an embodiment of the present application; FIG. 6 is a schematic diagram of the position of a sub-block and a current block under horizontal partitioning provided by an embodiment of the present application; FIG. 7 is a schematic diagram of the position of a sub-block and a current block under vertical partitioning provided by an embodiment of the present application; FIG. 8 is a schematic diagram of a gradient histogram provided by an embodiment of the present application; FIG. 9 is a schematic diagram of a template area provided by an embodiment of the present application; FIG. 10 is a schematic flowchart of an encoding method provided by an embodiment of the present application; FIG. 11 is a schematic flowchart of an encoding method and a decoding method provided by an embodiment of the present application; FIG. 12 is a schematic composition structure diagram of an encoder provided by an embodiment of the present application; FIG. 13 is a schematic specific hardware structure diagram of an encoder provided by an embodiment of the present application; FIG. 14 is a schematic composition structure diagram of a decoder provided by an embodiment of the present application; FIG. 15 is a schematic specific hardware structure diagram of a decoder provided by an embodiment of the present application; FIG. 16 is a schematic composition structure diagram of an encoding and decoding system provided by an embodiment of the present application. Detailed Embodiments In order to understand the features and technical content of the embodiments of the present application in more detail, the implementation of the embodiments of the present application will be described in detail below with reference to the accompanying drawings. The attached drawings are for reference and illustration only, and are not intended to limit the embodiments of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application. In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict. It should also be noted that the terms "first / second / third" involved in the embodiments of this application are only used to distinguish similar objects and do not represent a specific order for the objects. It can be understood that "first / second / third" can be interchanged in a specific order or sequence when allowed, so that the embodiments of this application described here can be implemented in an order other than that illustrated or described here. Before further elaborating on the embodiments of the present application, the nouns and terms involved in the embodiments of the present application are explained first. The nouns and terms involved in the embodiments of the present application are applicable to the following explanations: Coding Block (CB); Block Matching (BM); Coding Unit (CU); Block Vector (BV); Motion Vector (MV); Sum of Absolute Difference (SAD); Sum of Absolute Transformed Difference (SATD); Mean Square Error (MSE); Sum of Squared Differences (SSD); Mean Absolute Deviation (MAD); Mean Square Differences (MSD); Normalized Correlation Coefficient (NCC); H.266 / Versatile Video Coding (VVC); VVC Test Model (VTM); Template Matching (TM); Intra Template Matching Prediction (Intra TMP); Intra block copy (IBC); Enhanced Compression Model (ECM) for Beyond VVC. It can be understood that in video images, generally the first color component, the second color component, and the third color component are used to represent coding blocks. Among them, these three color components are respectively a luminance component, a blue chrominance component, and a red chrominance component. Specifically, the luminance component is usually represented by the symbol Y, the blue chrominance component is usually represented by the symbol Cb or U, and the red chrominance component is usually represented by the symbol Cr or V. Thus, video images can be represented in the YCbCr format or the YUV format. The following will describe each embodiment of the present application in detail with reference to the accompanying drawings. Referring to FIG. 1, which shows a schematic block diagram of the composition of an encoder provided by an embodiment of the present application. As shown in FIG. 1, the encoder (specifically, a "video encoder") 100 may include a transform and quantization unit 101, an intra-frame estimation unit 102, an intra-frame prediction unit 103, a motion compensation unit 104, a motion estimation unit 105, an inverse transform and inverse quantization unit 106, a filter control analysis unit 107, a filtering unit 108, an encoding unit 109, a decoded image buffer unit 110, etc. Among them, the filtering unit 108 can implement deblocking filtering and sample adaptive offset (SAO) filtering, and the encoding unit 109 can implement header information encoding and context-based adaptive binary arithmetic coding (CABAC). For the input original video signal, a video coding block can be obtained through the division of a coding tree unit (CTU). Then, the residual pixel information obtained after intra-frame or inter-frame prediction is transformed by the transform and quantization unit 101 for the video coding block, including transforming the residual information from the pixel domain to the transform domain and quantizing the obtained transform coefficients to further reduce the bit rate; the intra-frame estimation unit 102 and the intra-frame prediction unit 103 are used for intra-frame prediction of the video coding block; specifically, the intra-frame estimation unit 102 and the intra-frame prediction unit 103 are used to determine the intra-frame prediction mode to be used for encoding the video coding block; the motion compensation unit 104 and the motion estimation unit 105 are used to perform inter-frame predictive coding of the received video coding block relative to one or more blocks in one or more reference frames to provide temporal prediction information; the motion estimation performed by the motion estimation unit 105 is a process of generating a motion vector, and the motion vector can estimate the motion of the video coding block, and then the motion compensation unit 104 performs motion compensation based on the motion vector determined by the motion estimation unit 105; after determining the intra-frame prediction mode, the intra-frame prediction unit 103 is further used to provide the selected intra-frame prediction data to the encoding unit 109, and the motion estimation unit 105 also sends the calculated and determined motion vector data to the encoding unit 109; in addition, the inverse transform and inverse quantization unit 106 is used for the video coding block of Reconstruction: Reconstruct the residual block in the pixel domain. The reconstructed residual block removes blocking artifact through the filter control analysis unit 107 and the filtering unit 108, and then adds the reconstructed residual block to a predictive block in the frame of the decoded image buffer unit 110 to generate a reconstructed video coding block; the coding unit 109 is used to code various coding parameters and the quantized transform coefficients. In the CABAC-based coding algorithm, the context can be based on adjacent coding blocks and can be used to code the information indicating the determined intra prediction mode, and output the bitstream of the video signal; while the decoded image buffer unit 110 is used to store the reconstructed video coding blocks for prediction reference. As the video image coding progresses, new reconstructed video coding blocks will be continuously generated, and these reconstructed video coding blocks will be stored in the decoded image buffer unit 110. Referring to FIG. 2, it shows a schematic block diagram of the composition of a decoder provided by an embodiment of the present application. As shown in FIG. 2, the decoder (specifically, a "video decoder") 200 includes a decoding unit 201, an inverse transform and inverse quantization unit 202, an intra prediction unit 203, a motion compensation unit 204, a filtering unit 205, a decoded image buffer unit 206, etc. Among them, the decoding unit 201 can implement header information decoding and CABAC decoding, and the filtering unit 205 can implement deblocking filtering and SAO filtering. The input video signal is coded through the encoding process of FIG. 1, and then the bitstream of the video signal is output; the bitstream is input into the decoder 200, and first passes through the decoding unit 201 to obtain the decoded transform coefficients; the transform coefficients are processed by the inverse transform and inverse quantization unit 202 to generate a residual block in the pixel domain; the intra prediction unit 203 can be used to generate prediction data of the current video decoding block based on the determined intra prediction mode and the data of the previously decoded blocks from the current frame or picture; the motion compensation unit 204 determines the prediction information for the video decoding block by analyzing the motion vector and other associated syntax elements, and uses the prediction information to generate a predictive block of the video decoding block being decoded; by summing the residual block from the inverse transform and inverse quantization unit 202 and the corresponding predictive block generated by the intra prediction unit 203 or the motion compensation unit 204, a decoded video block is formed; the decoded video signal passes through the filtering unit 205 to remove blocking artifact, which can improve the video quality; then the decoded video block is stored in the decoded image buffer unit 206. The decoded image buffer unit 206 stores the reference image for subsequent intra prediction or motion compensation, and is also used for the output of the video signal, that is, the original video signal is restored. Further, an embodiment of the present application also provides a network architecture of an encoding and decoding system including an encoder and a decoder. Among them, FIG. 3 shows a schematic diagram of a network architecture of an encoding and decoding system provided by an embodiment of the present application. As shown in FIG. 3, the network architecture includes one or more electronic devices 13 to 1N and a communication network 01. Among them, the electronic devices 13 to 1N can perform video interaction through the communication network 01. During implementation, the electronic device can be various types of devices with video encoding and decoding functions. For example, the electronic device can include a smart phone, a tablet computer, a personal computer, a personal digital assistant, a navigator, a digital phone, a video phone, a television, a sensing device, a server, etc., which are not specifically limited here. In addition, the decoder or encoder described in the embodiment of the present application can be the above-mentioned electronic device. In order to fully improve the prediction accuracy, in VVC, an intra sub-block partitioning mode is used to divide the coding block into several sub-blocks. In this way, the reconstructed pixels after encoding the previous sub-block can provide a reference for the next sub-block, and the same intra prediction mode is shared by each sub-block. However, in the actual encoding process, the sub-blocks divided from the same coding block may have different content characteristics. Using the same intra prediction mode for prediction of each sub-block will reduce the prediction accuracy, thereby affecting the encoding efficiency. Based on this, an embodiment of the present application provides an encoding and decoding method. Whether it is the encoding end or the decoding end, when the current block uses the intra sub-block partitioning mode, the content characteristics of the reconstructed area are fully utilized, the second intra prediction mode is adaptively selected, and the sub-blocks are fused and predicted in combination with the first intra prediction mode to improve the prediction accuracy of the intra sub-block partitioning mode, thereby further improving the encoding and decoding performance. It should be noted that the method of the embodiment of the present application is mainly applied to the intra prediction unit 103 part shown in FIG. 1 and the intra prediction unit 203 part shown in FIG. 2. That is to say, the embodiment of the present application can be applied to the encoder, the decoder, or even both the encoder and the decoder at the same time, but the embodiment of the present application does not make specific limitations. It should also be noted that when applied to the encoding end part, the "current block" specifically refers to the coding block to be intra predicted currently; when applied to the decoding end part, the "current block" specifically refers to the decoding block to be intra predicted currently. In an embodiment of the present application, referring to FIG. 4, it shows a schematic flowchart of a decoding method provided by an embodiment of the present application. As shown in FIG. 4, the method may include: S401: Decode the bitstream to determine the prediction parameters of the current block, where the prediction parameters include the first intra prediction mode; The prediction parameters further include any one or more parameters for decoding the current block except the first intra prediction mode. In some embodiments, the prediction parameter further includes a first syntax element, and the first syntax element is used to indicate whether the current block uses an intra sub-block partitioning mode. Exemplarily, decoding the bitstream to determine the prediction parameter of the current block includes: decoding the bitstream to determine the first syntax element of the current block; when it is determined that the current block uses the intra sub-block partitioning mode according to the first syntax element, decoding the bitstream to determine the first intra prediction mode. That is to say, when it is determined that the current block uses the intra sub-block partitioning mode or a derivative mode of the intra sub-block partitioning mode, decoding the bitstream to determine the first intra prediction mode. Here, the first intra prediction mode may be the best intra prediction mode of the current block. The best intra prediction mode may be determined by the encoding end and the first intra prediction mode is written into the bitstream for the decoding end to read, or the best intra prediction mode may also be derived by the decoding end according to the reconstructed adjacent blocks of the current block. The derivative mode of the intra sub-block partitioning mode may be a new prediction mode based on the intra sub-block partitioning and is different from the traditional intra sub-block partitioning mode. The encoding end can make an encoding decision for different modes, select the optimal prediction mode, and transmit the syntax element information through the bitstream for the decoding end to read. Further, when it is determined that the current block does not use the intra sub-block partitioning mode according to the first syntax element, decoding the bitstream to determine other intra prediction modes, where the other intra prediction modes are modes different from the intra sub-block partitioning mode. In some embodiments, the prediction parameter further includes a second syntax element, and the second syntax element is used to indicate the partitioning type of the current block. Exemplarily, decoding the bitstream to determine the prediction parameter of the current block further includes: when it is determined that the current block uses the intra sub-block partitioning mode according to the first syntax element, decoding the bitstream to determine the second syntax element. That is to say, when it is determined that the current block uses the intra sub-block partitioning mode or a derivative mode of the intra sub-block partitioning mode, it is also necessary to decode the second syntax element to determine the partitioning type of the current block, so as to divide the current block into several sub-blocks according to the partitioning type and perform prediction and reconstruction in sequence from left to right or from top to bottom. Exemplarily, the partitioning type of the current block includes vertical partitioning or horizontal partitioning, as shown in FIG. 5. The intra sub-block partitioning mode (ISP) enables intra prediction coding to be based on sub-blocks in the CU, and the reconstructed pixels after encoding the previous sub-block provide reference samples for the next sub-block. In some embodiments, the method further includes: determining the partitioning type of the current block according to the second syntax element; determining the number of sub-blocks partitioned in the current block according to the size of the current block; determining the decoding order of the sub-blocks in the current block according to the partitioning type and the number of partitions of the current block; and determining the target sub-block in the current block according to the decoding order. That is to say, when it is determined that the current block uses the intra sub-block partitioning mode or a derivative mode of the intra sub-block partitioning mode, it is also necessary to determine the number of partitions according to the size of the current block. Exemplarily, the number of partitions is 2 or 4. Exemplarily, the variable intra_subpartitions_mode_flag is the first syntax element, which is used to indicate whether the current block uses the intra sub-block partitioning mode. The variable intra_subpartitions_split_flag is the second syntax element, which is used to indicate whether the partitioning type of the intra sub-block is horizontal or vertical. The variable IntraSubPartitionsSplitType specifies the specific partitioning type used for the current luma coding block, as shown in Table 1. The derivation process of IntraSubPartitionsSplitType is as follows: – If intra_subpartitions_mode_flag is equal to 0, then IntraSubPartitionsSplitType is set to 0. – Otherwise, IntraSubPartitionsSplitType is set to 1 + intra_subpartitions_split_flag. Table 1 Correspondence between the values and names of the variable IntraSubPartitionsSplitType The variable NumIntraSubPartitions is used to specify the number of partitions of the sub-blocks into which the intra luma coding block is divided. The derivation process of NumIntraSubPartitions is as follows: – If IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT, then NumIntraSubPartitions is set to 1. – Otherwise, if one of the following conditions is true, then NumIntraSubPartitions is set to 2: – cbWidth is equal to 4 and cbHeight is equal to 8 – cbWidth is equal to 8 and cbHeight is equal to 4 – Otherwise, NumIntraSubPartitions is set to be equal to 4. The current block can be divided into NumIntraSubPartitions sub - blocks, and prediction and reconstruction of each sub - block are completed according to the preset decoding order. As shown in Figure 6, under horizontal division, the number of sub - blocks is 4, that is, the variable intra_subpartitions_split_flag is 0, IntraSubPartitionsSplitType is 1, the variable NumIntraSubPartitions is 4, and the sub - block numbers from 0 to 3 are the decoding order of the sub - blocks. As shown in Figure 7, under vertical division, the number of sub - blocks is 4, that is, the variable intra_subpartitions_split_flag is 1, IntraSubPartitionsSplitType is 2, the variable NumIntraSubPartitions is 4, and the sub - block numbers from 0 to 3 are the decoding order of the sub - blocks. For the current sub - block, prediction is performed using the first intra - frame prediction mode to determine the first intra - frame prediction value of the current sub - block; prediction is performed using the second intra - frame prediction mode to determine the second intra - frame prediction value of the current sub - block; and the intra - frame prediction value of the current sub - block is determined according to the first intra - frame prediction value and the second intra - frame prediction value. S402: Determine the first intra - frame prediction value of the target sub - block in the current block according to the first intra - frame prediction mode; It should be noted that the first intra - frame prediction mode can be any intra - frame prediction mode. Exemplarily, the first intra - frame prediction mode includes but is not limited to: planar mode (PLANAR mode), direct current mode (DC mode), 65 angle prediction modes, and other intra - frame prediction modes. It should also be noted that the target sub - block can be one or more sub - blocks in the current block. Exemplarily, the target sub - block can be any sub - block in the current block or some specific sub - blocks in the current block. S403: Determine the second intra - frame prediction mode of the target sub - block based on the reference sample values of the target sub - block, where the second intra - frame prediction mode includes one or more intra - frame prediction modes; The reference sample values (reference samples) are the adjacent reconstructed sample values of the target sub - block, specifically the reconstructed sample values of the reconstructed adjacent blocks of the target sub - block. In the embodiments of the present application, by making full use of the reference sample values of the target sub - block, the second intra - frame prediction mode of the target sub - block is determined, and weighted fusion prediction of the target sub - block is performed in combination with the first intra - frame prediction mode, improving the prediction accuracy of the intra - frame sub - block division mode. In some embodiments, the reconstructed neighboring blocks of the first sub-block in the current block include at least one of the following: the left neighboring block of the first sub-block, the upper neighboring block of the first sub-block, where the first sub-block is the first decoded sub-block determined according to the decoding order of the sub-blocks in the current block. In other embodiments, the reconstructed neighboring blocks of the first sub-block further include at least one of the following: the lower left neighboring block of the first sub-block, the upper left neighboring block, the upper right neighboring block, other neighboring blocks, and non-neighboring blocks. In some embodiments, the reconstructed neighboring blocks of other sub-blocks in the current block include one or more reconstructed sub-blocks in the current block. Part or all of the reconstructed values in the one or more reconstructed sub-blocks are used as reference sample values to adaptively derive the second intra-frame prediction mode. Among them, the other sub-blocks are one or more sub-blocks other than the first sub-block determined according to the decoding order of the sub-blocks in the current block. Exemplarily, taking the sub-block numbered 2 in FIGS. 6 and 7 as an example, the reconstructed neighboring blocks include, but are not limited to, the sub-block numbered 0, or the sub-block numbered 1, or the sub-blocks numbered 0 and 1. In other embodiments, the reconstructed neighboring blocks of the other sub-blocks may further include at least one of the following: other reconstructed neighboring blocks and non-neighboring blocks of the other sub-blocks. In some embodiments, the prediction parameter further includes a third syntax element, and the third syntax element is used to indicate whether the current block uses the second intra-frame prediction mode for fusion prediction; correspondingly, when decoding the bitstream to determine the prediction parameter of the current block, it further includes: when it is determined according to the first syntax element that the current block uses the intra-frame sub-block partitioning mode, decoding the bitstream to determine the third syntax element. Furthermore, the method further includes: when it is determined according to the value of the third syntax element that the current block uses the second intra-frame prediction mode for fusion prediction, determining the second intra-frame prediction mode of the target sub-block based on the reference sample values; when it is determined according to the value of the third syntax element that the current block does not use the second intra-frame prediction mode for fusion prediction, determining the intra-frame prediction value of the target sub-block based on the first intra-frame prediction value. Exemplarily, the variable intra_subpartitions_fusion_flag is the third syntax element, which is used to indicate whether the intra-frame sub-blocks perform fusion prediction. When intra_subpartitions_fusion_flag is equal to 0, no fusion prediction is performed. When intra_subpartitions_fusion_flag is equal to 1, fusion prediction is performed, that is, the second intra-frame prediction mode is determined according to the reference sample values of the current sub-block. In some embodiments, determining the intra prediction mode in the second frame of the target sub-block based on the reference sample value includes: using a first derivation mode based on the reference sample value to determine the prediction performance parameters of multiple candidate intra prediction modes; and determining one or more intra prediction modes included in the intra prediction mode in the second frame according to the prediction performance parameters. The prediction performance parameter is used to represent the performance quality of the candidate intra prediction mode when predicting the reference sample value and can be used as a basis for mode selection. In some embodiments, the first derivation mode may be a derivation mode preset at the encoding and decoding ends. In some other embodiments, the method further includes: decoding the code stream to determine the first derivation mode. That is, the encoding end determines the optimal derivation mode from multiple candidate derivation modes through encoding decision-making, and the encoding end writes the optimal derivation mode into the code stream for the decoding end to read. Exemplarily, the first derivation mode includes a gradient derivation mode; the mode derivation method of the gradient derivation mode may include: performing gradient analysis on the reference sample value to determine the gradient intensity of multiple candidate intra prediction modes in the first mode set; when the gradient intensities of the multiple candidate intra prediction modes include non-zero terms, determining at least one gradient intensity according to the order from large to small of the gradient intensities; determining at least one mode index according to the gradient angles corresponding to the at least one gradient intensity; and determining one or more intra prediction modes included in the intra prediction mode in the second frame according to the at least one mode index. The first mode set includes multiple candidate intra prediction modes during gradient derivation. Exemplarily, the first mode set includes: PLANAR mode, DC mode, and 65 angle prediction modes. The first mode set may further include other intra prediction modes. The mode derivation method of the gradient derivation mode may further include: when the gradient intensities of the multiple candidate intra prediction modes do not include non-zero terms, determining that the intra prediction mode in the second frame includes a first preset mode; when the gradient intensities of the multiple candidate intra prediction modes include non-zero terms and the intra prediction mode in the second frame includes a second preset mode, updating the gradient intensity of the second preset mode to a first gradient intensity and re-searching for other modes of the intra prediction mode in the second frame according to the updated gradient intensity. That is, during gradient derivation, when the gradient intensities of all candidate intra prediction modes are all 0, the first preset mode may be selected as the intra prediction mode in the second frame, and the first preset mode may be the PLANAR mode or other default modes. When the gradient intensities of all candidate intra prediction modes are not all 0 and the second preset mode is searched, the gradient intensity of the second preset mode may be set to the first gradient intensity (for example, -1), so that the intra prediction mode in the second frame does not include the second preset mode, and the second preset mode may be the first intra prediction mode, ensuring that the intra prediction mode in the second frame searched based on the gradient derivation mode does not include the first intra prediction mode. Exemplarily, the variable baseMode is the first intra prediction mode, the variable fusionMode is the second intra prediction mode. When fusionMode includes more than two intra prediction modes, the variable NumFusionMode is the number of elements in fusionMode. Exemplarily, take the sub-block numbered 1 divided horizontally as an example. Assume that the coordinate of the upper-left pixel position of the current sub-block relative to the upper-left pixel position of the image is (x, y), the width of the sub-block is Width, and the height is Height. Input: The luminance pixels of this sub-block in the reconstructed region of the current coding block are p[x][y], where x = 0...Width - 1, y = -1..-Height, that is, the sub-block region coded as 0. The origin [0][0] is the pixel coordinate at the upper left within sub-block 0. If taking the sub-block numbered 2 as an example, then the input includes but is not limited to the sub-block numbered 0, or the sub-block numbered 1, or the reconstructed values of the pixels within the sub-blocks numbered 0 and 1. If taking the sub-block numbered 0 as an example, the input includes but is not limited to the reconstructed values of the pixels within the left adjacent block and / or the upper adjacent block. The gradient derivation process is as follows: Let mapHgV = {{2, 1}, {1, 2}}, mapVgH = {{3, 4}, {4, 3}} Let angTable = {0, 2048, 4096, 6144, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 47104, 53248, 59392, 65536} Let angOffset = {18, 18, 50, 50} Let HoG

[0067] be an array containing the gradient intensities of each intra prediction mode. At the start of this process, it is initialized to zero. For p[x][y], where x = 1...Width - 2, y = -2..-Height + 1, that is, only calculate the gradients of the internal pixel positions in the reconstructed region. Calculate: The vertical gradient of each pixel gHor[x][y] = p[x - 1][y - 1] + 2 × p[x - 1][y] + p[x - 1][y + 1] – p[x + 1][y - 1] – 2 × p[x + 1][y] – p[x + 1][y + 1] The horizontal gradient gVer[x][y] of each pixel = p[x - 1][y - 1] + 2 × p[x][y - 1] + p[x + 1][y - 1] – p[x - 1][y + 1] – 2 × p[x][y + 1] – p[x + 1][y + 1] signH[x][y] = gHor[x][y] < 0? 1 : 0 signV[x][y] = gVer[x][y] < 0? 1 : 0 HgV[x][y] = (abs(gHor[x][y]) > abs(gVer[x][y])? 1 : 0) region[x][y] = (HgV[x][y] == 1? mapHgV[signH[x][y]][signV[x][y]] : mapVgH[signH[x][y]][signV[x][y]]) grad[x][y] = (HgV[x][y] == 1? abs(gVer[x][y]) / abs(gHor[x][y]) : abs(gVer[x][y]) / abs(gHor[x][y])) grad[x][y] = round(grad[x][y] * (1 << 16)) Calculate the closest intra - prediction mode index angIdx[x][y] = argmin i(abs(angTable[i] – grad[x][y])) Calculate the intra - prediction mode ipm[x][y] = angOffset[region[x][y]] + angIdx[x][y] The gradient intensity iAmp[x][y] = abs(gHor[x][y]) + abs(gVer[x][y]) Accumulate the gradient intensity iAmp according to the corresponding intra - prediction mode ipm. Build a gradient histogram with the intra - prediction mode ipm as the abscissa and the gradient intensity iAmp as the ordinate, as shown in Figure 8. The array Weight is a copy variable of HOG and is used to calculate the weighted weights. If the histogram HOG does not contain non - zero terms, then all the amplitudes in Figure 8 are 0, and the fusionMode is set to the PLANAR mode or other default modes. Otherwise, set the fusionMode to argmax i(HoG[i]), and the fusionMode is equal to the baseMode. Set HoG[fusionMode] to - 1; If fusionMode is equal to baseMode, then search again and set fusionMode to argmax i(HoG[i]). If NumFusionMode is greater than 1, then it is necessary to search again until the array fusionMode is filled. Output: The second-frame prediction mode fusionMode derived from the gradient, and the mode index range is [0, 66]. Exemplarily, the first derivation mode includes a template derivation mode; the mode derivation method of the template derivation mode may include: predicting the reference sample value according to multiple candidate intra-frame prediction modes in the second mode set, and determining the predicted sample value of the reference sample value; according to the reference sample value and the predicted sample value, determining the error values of multiple candidate intra-frame prediction modes in the second mode set; according to the order of the error values from small to large, determining one or more intra-frame prediction modes included in the second-frame prediction mode. The second mode set includes multiple candidate intra-frame prediction modes during template derivation. Exemplarily, the second mode set may include: PLANAR mode, DC mode, and 65 angle prediction modes. The second mode set may also include other intra-frame prediction modes. It should be noted that when performing mode derivation based on the TM technology, the reference sample value may be the reconstructed sample value in the sub-block template area. According to the reference sample value in the template area, multiple candidate intra-frame prediction modes in the second mode set are used to predict the target sub-block template area to obtain the predicted sample value of the template area. Exemplarily, as shown in FIG. 9, when both the upper reference pixel and the left reference pixel are available, the template shape is as shown in (a) in FIG. 9; when only the left reference pixel is available, the template shape is as shown in (b) in FIG. 9; when only the upper reference pixel is available, the template shape is as shown in (c) in FIG. 9. The template area may also include at least one of the following: the upper left adjacent block, the lower left adjacent block, and the upper right adjacent block. Traverse the second mode set, perform prediction on the sub-block template area, and calculate some error values between the predicted value and the reconstructed value, including but not limited to the sum of absolute differences (SAD), the sum of transformed absolute differences (SATD), the sum of squared differences (SSE), the mean absolute difference (MAD), the mean absolute error (MAE), the mean squared error (MSE), the rate distortion cost (RDO), etc. Select NumFusionMode intra-frame prediction modes through the error values and assign them to the array fusionMode. Take the sub-block numbered 1 with horizontal division as an example. Traverse the second mode set, perform prediction on the sub-block area numbered 0, and calculate some error values between the predicted value and the reconstructed value, including However, it is not limited to the sum of absolute differences (SAD), sum of absolute transformed differences (SATD), sum of squared errors (SSE), mean absolute difference (MAD), mean absolute error (MAE), mean squared error (MSE), etc. Select NumFusionMode intra prediction modes through the error values and assign them to the array fusionMode. Take the sub-block numbered 2 divided horizontally as an example. Traverse the second mode set, perform prediction on the area including but not limited to numbered 0 or 1 or both 0 and 1, calculate some error values between the predicted value and the reconstructed value, including but not limited to the sum of absolute differences (SAD), sum of absolute transformed differences (SATD), sum of squared errors (SSE), mean absolute difference (MAD), mean absolute error (MAE), mean squared error (MSE), etc. Select NumFusionMode intra prediction modes through the error values and assign them to the array fusionMode. Taking the sum of absolute differences as an example, select NumFusionMode intra prediction modes with the smallest SAD as fusionMode. In some embodiments, the second intra prediction mode further includes a third preset mode. That is to say, the second intra prediction mode may include some fixed modes, or when the first intra prediction mode and the derived second intra prediction mode meet certain conditions, it is determined that the second intra prediction mode includes the third preset mode. Exemplarily, the third preset mode may be the planar mode (PLANAR mode). S404: Determine the second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; It can be understood that when the second intra prediction mode includes one intra prediction mode, determine one intra prediction value of the target sub-block according to the second intra prediction mode; when the second intra prediction mode includes multiple (more than two) intra prediction modes, determine multiple second intra prediction values of the target sub-block according to the second intra prediction mode. S405: Determine the intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; Exemplarily, perform weighted fusion on the first intra prediction value and the second intra prediction value to determine the intra prediction value of the target sub-block. Among them, the weighted fusion includes weighted fusion based on different weights and average operation based on the same weight. In some embodiments, the method further includes: determining a first weight value of the first intra-prediction value and a second weight value of the second intra-prediction value based on a preset weight allocation strategy, where the second weight value includes one or more weight values corresponding to one or more intra-prediction values included in the second intra-prediction value. That is, when the second intra-prediction mode includes multiple (more than two) intra-prediction modes, the second weight value also includes multiple weight values. Exemplarily, the weight allocation strategy includes: when the second intra-prediction mode includes a first preset mode, determining the first weight value as 1 and the second weight value as 0. For example, the first preset mode may be the PLANAR mode or other default modes, and the other default modes may be an angular prediction mode. Exemplarily, the weight allocation strategy includes: when the second intra-prediction mode does not include the first preset mode, determining that the first weight value and the second weight value are equal. For example, each weight value is a constant 1 / n, where n is the number of modes participating in weighted fusion. Exemplarily, the weight allocation strategy may include determining the weight value based on the prediction performance parameter of the intra-prediction mode, where the prediction performance parameter is used to represent the performance advantages and disadvantages of the first intra-prediction mode and the second intra-prediction mode when predicting the reference sample value, and can be used as the basis for weight allocation to improve the prediction accuracy of the current block. Specifically, the weight allocation strategy includes: adding the prediction performance parameter of the first intra-prediction mode and the prediction performance parameter of the second intra-prediction mode to obtain a total prediction performance parameter; dividing the prediction performance parameter of the first intra-prediction mode by the total prediction performance parameter to obtain a first coefficient; dividing the prediction performance parameter of the second intra-prediction mode by the total prediction performance parameter to obtain a second coefficient; and performing weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value. In some embodiments, performing weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value includes: calculating the product of the first coefficient and the total weight value to obtain the first weight value; calculating the product of the second coefficient and the total weight value to obtain the second weight value; In some other embodiments, performing weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value includes: dividing the total weight value into a third weight value and a fourth weight value; calculating the product of the first coefficient and the third weight value and then adding the fourth weight value to obtain the first weight value; calculating the product of the second coefficient and the third weight value to obtain the second weight value. Exemplarily, the variable baseMode is the first intra prediction mode, and the variable baseModeWeight is the first weight value. The variable fusionMode is the second intra prediction mode. The array fusionModeWeight is the second weight value for fusionMode, and the variable NumFusionMode is the number of elements in fusionMode and fusionModeWeight. When the prediction performance parameter is the gradient strength, the calculation process of the first weight value baseModeWeight and the second weight value fusionModeWeight includes but is not limited to the following: Assume that the sum of total weights is sumOfWeight. If fusionMode is the PLANAR mode or other default modes, then baseModeWeight is sumOfWeight and fusionModeWeight is 0; If HOG[baseMode] is 0, then baseModeWeight is sumOfWeight, fusionModeWeight is 0, or assume that when NumFusionMode is 1, both baseModeWeight and fusionModeWeight are If fusionMode is not the PLANAR mode or other default modes, and assume that when NumFusionMode is 1, then baseModeWeight and fusionModeWeight are both Or baseModeWeight and fusionModeWeight are and Or baseModeWeight and fusionModeWeight are and and so on. Exemplarily, when the prediction performance parameter is some error values between the predicted value and the reconstructed value, taking the sum of absolute differences SAD as an example, the calculation process of the first weight value baseModeWeight and the second weight value fusionModeWeight includes but is not limited to the following: Assume that the sum of total weights is sumOfWeight. If the fusionMode is PLANAR mode or other default modes, then the baseModeWeight is the sumOfWeight and the fusionModeWeight is 0; If the fusionMode is not PLANAR mode or other default modes, assuming NumFusionMode is 1, then both the baseModeWeight and the fusionModeWeight are Or the baseModeWeight and the fusionModeWeight are And Or the baseModeWeight and the fusionModeWeight are And And so on. Furthermore, for the current sub-block, intra-frame weighted fusion prediction is performed. It should be noted that when performing weighted prediction, the predicted values of all modes can be directly weighted, or weighted one by one. When weighting one by one, the predicted value of each mode is weighted using the weight values of (1 - p) and p when incorporated. (1 - p) is the weight value of the previously weighted result, and p is the weight value of the newly incorporated mode. The acquisition method of p can be a constant or a value related to the prediction performance parameter. When p is a value related to the prediction performance parameter, (1 - p) can be the sum of the prediction performance parameters of the previously participating weighted modes, and p is the prediction performance parameter of the newly incorporated prediction mode. In some embodiments, the method further includes: saving at least one of the first intra-frame prediction mode, the second intra-frame prediction mode, the first weight value, and the second weight value of the target sub-block. To make full use of the mode information of the current block by the subsequent coding block, the second intra-frame prediction mode and weight and other information can be stored in the prediction information of each sub-block, and the first intra-frame prediction mode can be stored in the prediction information of the current block as a reference for the subsequent coding block to assist the prediction of the subsequent coding block. S406: Determine the reconstruction value of the target sub-block based on the intra-frame predicted value of the target sub-block. Exemplarily, the method further includes: decoding the code stream to determine the residual coefficient of the target sub-block; performing inverse quantization and inverse transformation on the residual coefficient, and combining with the intra-frame predicted value of the sub-block to obtain the reconstruction value of the sub-block. It should be noted that if all sub-blocks within the current block are reconstructed, the intra-frame sub-block partitioning mode of the current block will be exited, and the decoding process of the subsequent image block will continue. It should be noted that the target sub-block decoded by using the decoding method provided in the embodiments of the present application may be one or more sub-blocks in the current block. Exemplarily, the target sub-block may be any sub-block in the current block, or may be some specific sub-blocks in the current block. Exemplarily, the specific sub-blocks may be other sub-blocks except the first sub-block. When the sub-block is the first sub-block, the intra prediction value of the first sub-block is determined based on the first intra prediction value. When the sub-block is other sub-blocks, weighted prediction is performed using both the first intra prediction mode and the second intra prediction mode. With the above technical solution, at the decoding end, when the current block uses the intra sub-block partitioning mode, the content characteristics of the reconstructed area are fully utilized, the second intra prediction mode is adaptively selected, and the sub-blocks are fused and predicted in combination with the first intra prediction mode, so as to improve the prediction accuracy of the intra sub-block partitioning mode, thereby further improving the decoding performance. In another embodiment of the present application, referring to FIG. 10, which shows a schematic flowchart of an encoding method provided in the embodiments of the present application. As shown in FIG. 10, the encoding method may include: S1001: Determine the first intra prediction mode of the current block; Exemplarily, when it is determined that the current block allows the use of the intra sub-block partitioning mode, the first intra prediction mode of the current block is determined. Among them, the syntax element used to indicate whether the current block allows the use of the intra sub-block partitioning mode may include at least one of the following: coding tree unit-level syntax element, picture-level syntax element, sequence-level syntax element, etc. When it is determined that the current block allows the use of the intra sub-block partitioning mode or a derived mode of the intra sub-block partitioning mode according to this syntax element, the first intra prediction mode is determined. Here, the first intra prediction mode may be any candidate intra prediction mode. The encoding end selects the best intra prediction mode of the current block as the prediction parameter of the current block through encoding decision and writes it into the bitstream for the decoding end to read. The first intra prediction mode may also be derived by the encoding end according to the reconstructed adjacent blocks of the current block. The derived mode of the intra sub-block partitioning mode may be a new prediction mode based on the intra sub-block partitioning and is different from the traditional intra sub-block partitioning mode. At the encoding end, different modes can be encoded and decided to select the optimal prediction mode, and the syntax element information is transmitted through the bitstream for the decoding end to read. In some embodiments, the method further includes: determining a plurality of candidate partitioning types of the current block; determining the number of sub-blocks partitioned in the current block according to the size of the current block; determining a plurality of candidate coding orders of the sub-blocks in the current block according to the plurality of candidate partitioning types and the number of partitions of the current block; determining a target sub-block in the current block according to the candidate coding order. That is, when it is determined that the current block uses an intra sub-block partitioning mode or a derived mode of the intra sub-block partitioning mode, the current block also needs to be partitioned into a plurality of sub-blocks according to the plurality of candidate partitioning types, and prediction and reconstruction are sequentially performed in the order from left to right or from top to bottom. Exemplarily, the candidate partitioning types include vertical partitioning or horizontal partitioning. As shown in FIG. 5. The intra sub-block partitioning mode (ISP) enables intra prediction coding to be based on sub-blocks in the CU, and the reconstructed pixels after encoding of the previous sub-block provide reference samples for the next sub-block. In addition, the number of partitions also needs to be determined according to the size of the current block. Exemplarily, the number of partitions is 2 or 4. S1002: Determine a first intra prediction value of the target sub-block in the current block according to the first intra prediction mode; It should be noted that the first intra prediction mode can be any candidate intra prediction mode. Exemplarily, the first intra prediction mode includes, but is not limited to: planar mode (PLANAR mode), direct current mode (DC mode), 65 angular prediction modes, and other intra prediction modes. It should also be noted that the target sub-block can be one or more sub-blocks in the current block. Exemplarily, the target sub-block can be any sub-block in the current block, or some specific sub-blocks in the current block. S1003: Determine a second intra prediction mode of the target sub-block based on the reference sample value of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; In some embodiments, when it is determined that the current block allows the use of the second intra prediction mode for fusion prediction, determine the second intra prediction mode of the target sub-block based on the reference sample value of the target sub-block; when it is determined that the current block does not allow the use of the second intra prediction mode for fusion prediction, determine the intra prediction value of the target sub-block based on the first intra prediction value. Among them, the syntax elements used to indicate whether the current block allows the use of the second intra prediction mode for merge prediction may include at least one of the following: coding tree unit level syntax elements, picture level syntax elements, sequence level syntax elements, etc. According to this syntax element, it is determined whether the current block allows the use of the second intra prediction mode for merge prediction in the intra sub-block partitioning mode or a derived mode of the intra sub-block partitioning mode. If allowed, the coding end uses the prediction mode provided by the embodiments of the present application to predict and reconstruct the current block, and compares the reconstruction value with the reconstruction values of other prediction modes to determine whether to use the prediction mode provided by the embodiments of the present application. If not allowed, the traditional ISP mode can be used for prediction and reconstruction. The reference samples are the adjacent reconstructed sample values of the target sub-block, specifically the reconstructed sample values of the reconstructed adjacent blocks of the target sub-block. The embodiments of the present application make full use of the reference sample values of the target sub-block to determine the second intra prediction mode of the target sub-block, and perform weighted merge prediction on the target sub-block in combination with the first intra prediction mode, improving the prediction accuracy of the intra sub-block partitioning mode. In some embodiments, the reconstructed adjacent blocks of the first sub-block in the current block include at least one of the following: the left adjacent block of the first sub-block, the upper adjacent block of the first sub-block, where the first sub-block is the first encoded sub-block determined according to the coding order of the sub-blocks in the current block. In other embodiments, the reconstructed adjacent blocks of the first sub-block further include at least one of the following: the lower left adjacent block of the first sub-block, the upper left adjacent block, the upper right adjacent block, other adjacent blocks, and non-adjacent blocks. In some embodiments, the reconstructed adjacent blocks of other sub-blocks in the current block include: one or more reconstructed sub-blocks in the current block, and some or all of the reconstruction values in the one or more reconstructed sub-blocks are used as reference sample values to adaptively derive the second intra prediction mode. Among them, the other sub-blocks are one or more sub-blocks other than the first sub-block determined according to the coding order of the sub-blocks in the current block. Exemplarily, taking the sub-block numbered 2 in FIGS. 6 and 7 as an example, the reconstructed adjacent blocks include, but are not limited to, the sub-block numbered 0, or the sub-block numbered 1, or the sub-blocks numbered 0 and 1. In other embodiments, the reconstructed adjacent blocks of other sub-blocks may further include at least one of the following: other adjacent blocks and non-adjacent blocks of the other sub-blocks that have been reconstructed. In some embodiments, determining the second intra prediction mode of the target sub-block based on the reference sample values includes: using the first derivation mode based on the reference sample values to determine the prediction performance parameters of multiple candidate intra prediction modes; according to the prediction performance parameters, determining one or more intra prediction modes included in the second intra prediction mode. Among them, the prediction performance parameters are used to represent the performance advantages and disadvantages of the candidate intra prediction modes when predicting the reference sample values, and can be used as a basis for mode selection. In some embodiments, the first derivation mode may be a derivation mode preset at the encoding and decoding ends. In some other embodiments, the method further includes: encoding the first derivation mode. That is, the encoding end determines the optimal derivation mode from multiple candidate derivation modes through encoding decision-making, and the encoding end writes the optimal derivation mode into the code stream for the decoding end to read. Exemplarily, the first derivation mode includes a gradient derivation mode; the mode derivation method of the gradient derivation mode may include: performing gradient analysis on reference sample values to determine the gradient intensities of multiple candidate intra prediction modes in the first mode set; when the gradient intensities of the multiple candidate intra prediction modes include non-zero terms, determining at least one gradient intensity according to the order from largest to smallest of the gradient intensities; determining at least one mode index according to the gradient angles corresponding to the at least one gradient intensity; and determining one or more intra prediction modes included in the second intra prediction mode according to the at least one mode index. The first mode set includes multiple candidate intra prediction modes during gradient derivation. Exemplarily, the first mode set includes: PLANAR mode, DC mode, and 65 angular prediction modes. The first mode set may also include other intra prediction modes. The mode derivation method of the gradient derivation mode may further include: when the gradient intensities of the multiple candidate intra prediction modes do not include non-zero terms, determining that the second intra prediction mode includes a first preset mode; when the gradient intensities of the multiple candidate intra prediction modes include non-zero terms and the second intra prediction mode includes a second preset mode, updating the gradient intensity of the second preset mode to a first gradient intensity and re-searching for other modes of the second intra prediction mode according to the updated gradient intensity. That is, during gradient derivation, when the gradient intensities of all candidate intra prediction modes are all 0, the first preset mode may be selected as the second intra prediction mode, and the first preset mode may be the PLANAR mode or other default modes. When the gradient intensities of all candidate intra prediction modes are not all 0 and the second preset mode is searched, the gradient intensity of the second preset mode may be set to the first gradient intensity (such as -1), so that the second intra prediction mode does not include the second preset mode, and the second preset mode may be the first intra prediction mode, ensuring that the second intra prediction mode searched based on the gradient derivation mode does not include the first intra prediction mode. Exemplarily, the first derivation mode includes a template derivation mode; the mode derivation method of the template derivation mode may include: predicting a reference sample value based on multiple candidate intra prediction modes in a second mode set to determine a predicted sample value of the reference sample value; determining an error value of multiple candidate intra prediction modes in the second mode set according to the reference sample value and the predicted sample value; determining one or more intra prediction modes included in the second intra prediction mode in ascending order of the error value. The second mode set includes multiple candidate intra prediction modes during template derivation. Exemplarily, the second mode set may include: PLANAR mode, DC mode, and 65 angular prediction modes. The second mode set may also include other intra prediction modes. It should be noted that when performing mode derivation based on the TM technology, the reference sample value may be the reconstructed sample value in the sub-block template area. Based on the reference sample value in the template area, multiple candidate intra prediction modes in the second mode set are used to predict the target sub-block template area to obtain the predicted sample value of the template area. Exemplarily, as shown in FIG. 9, the template area may include one of the following: when the upper left reference pixel, the upper reference pixel, and the left reference pixel are all available, the template shape is as shown in (a) in FIG. 9; when only the left reference pixel is available, the template shape is as shown in (b) in FIG. 9; when only the upper reference pixel is available, the template shape is as shown in (c) in FIG. 9. The template area may also include at least one of the following: the upper left adjacent block, the lower left adjacent block, and the upper right adjacent block. Traverse the second mode set, perform prediction on the sub-block template area, and calculate some error values between the predicted value and the reconstructed value, including but not limited to the sum of absolute differences (SAD), the sum of transformed absolute differences (SATD), the sum of squared differences (SSE), the mean absolute difference (MAD), the mean absolute error (MAE), the mean squared error (MSE), the rate distortion cost (RDO), etc. Select NumFusionMode intra prediction modes through the error values and assign them to the array fusionMode. In some embodiments, the second intra prediction mode further includes a third preset mode. That is to say, the second intra prediction mode may include certain fixed modes, or when the first intra prediction mode and the derived second intra prediction mode meet certain conditions, it is determined that the second intra prediction mode includes the third preset mode. Exemplarily, the third preset mode may be the planar mode (PLANAR mode). S1004: Determine the second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; It can be understood that when the intra prediction mode included in the second frame is one intra prediction mode, one intra prediction value of the target sub-block is determined according to the intra prediction mode in the second frame; when the intra prediction mode included in the second frame is multiple (more than two) intra prediction modes, multiple second intra prediction values of the target sub-block are determined according to the intra prediction mode in the second frame. S1005: Determine the intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; Exemplarily, the first intra prediction value and the second intra prediction value are weighted and fused to determine the intra prediction value of the target sub-block. Among them, the weighted fusion includes weighted fusion based on different weights and average operation based on the same weight. In some embodiments, the method further includes: determining a first weight value of the first intra prediction value and a second weight value of the second intra prediction value based on a preset weight assignment strategy, where the second weight value includes one or more weight values corresponding to one or more intra prediction values included in the second intra prediction value. That is to say, when the intra prediction mode included in the second frame is multiple (more than two) intra prediction modes, the second weight value also includes multiple weight values. Exemplarily, the weight assignment strategy includes: when the intra prediction mode in the second frame includes a first preset mode, determining the first weight value to be 1 and the second weight value to be 0. For example, the first preset mode may be the PLANAR mode or other default modes, and other default modes may be an angular prediction mode. Exemplarily, the weight assignment strategy includes: when the intra prediction mode in the second frame does not include the first preset mode, determining that the first weight value and the second weight value are equal. For example, each weight value is a constant 1 / n, where n is the number of modes participating in the weighted fusion. Exemplarily, the weight assignment strategy may include determining the weight value based on the prediction performance parameter of the intra prediction mode, where the prediction performance parameter is used to represent the performance quality of the first intra prediction mode and the second intra prediction mode when predicting the reference sample value, and can be used as the basis for weight assignment to improve the prediction accuracy of the current block. Specifically, the weight assignment strategy includes: adding the prediction performance parameter of the first intra prediction mode and the prediction performance parameter of the second intra prediction mode to obtain the total prediction performance parameter; dividing the prediction performance parameter of the first intra prediction mode by the total prediction performance parameter to obtain the first coefficient; dividing the prediction performance parameter of the second intra prediction mode by the total prediction performance parameter to obtain the second coefficient; and performing weight assignment according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value. In some embodiments, performing weight assignment according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value includes: calculating the product of the first coefficient and the total weight value to obtain the first weight value; calculating the product of the second coefficient and the total weight value to obtain the second weight value; In some other embodiments, weight distribution is performed according to a first coefficient and a second coefficient to obtain a first weight value and a second weight value, including: dividing a total weight value into a third weight value and a fourth weight value; calculating the product of the first coefficient and the third weight value, and then adding the fourth weight value, to obtain the first weight value; calculating the product of the second coefficient and the third weight value to obtain the second weight value. In some embodiments, the method further includes: saving at least one of a first intra prediction mode, a second intra prediction mode, a first weight value, and a second weight value of a target sub-block. In order to make full use of the mode information of the current block by subsequent coding blocks, information such as the second intra prediction mode and weights can be stored in the prediction information of each sub-block, and the first intra prediction mode can be stored in the prediction information of the current block as a reference for subsequent coding blocks to assist in the prediction of subsequent coding blocks. S1006: Determine a reconstruction value of the target sub-block based on the intra prediction value of the target sub-block; Exemplarily, the method further includes: obtaining residual information according to the original value and the intra prediction value of the sub-block, performing transformation and quantization on the residual information to obtain residual coefficients, and then performing inverse quantization and inverse transformation on the residual coefficients and combining with the intra prediction value of the sub-block to obtain the reconstruction value of the sub-block. It should be noted that if all sub-blocks within the current block are reconstructed, the intra sub-block partitioning mode of the current block will be exited, and the encoding process of other modes will continue, or the encoding process of subsequent image blocks will continue. S1007: Make an encoding decision based on the reconstruction value of the target sub-block to determine prediction parameters of the current block, where the prediction parameters include a first intra prediction mode; In some embodiments, when it is determined that all sub-blocks within the current block are reconstructed, an encoding decision is made according to the reconstruction value and the original value of the current block to determine whether to use the first intra prediction mode as the best intra prediction mode of the current block, and according to the decision result, the prediction parameters of the current block are determined. That is to say, the first intra prediction mode included in the prediction parameters is the best intra prediction mode of the current block. The best intra prediction mode can be determined by the encoding end and the first intra prediction mode is written into the code stream for the encoding end to read; the best intra prediction mode can also be derived by the encoding end according to the reconstructed adjacent blocks of the current block, and the decoding end can also derive the first intra prediction mode according to the reconstructed adjacent blocks of the current block. S1008: Encode the prediction parameters and write the obtained encoded bits into the code stream. In some embodiments, the prediction parameter further includes a first syntax element, and the first syntax element is used to indicate whether the current block uses an intra sub-block partitioning mode. Encoding the prediction parameter may include: encoding the first syntax element; and encoding a first intra prediction mode in the case where it is determined according to the first syntax element that the current block uses an intra sub-block partitioning mode. In some embodiments, the prediction parameter further includes a second syntax element, and the second syntax element is used to indicate the partitioning type of the current block. Encoding the prediction parameter further includes: encoding the second syntax element in the case where it is determined according to the first syntax element that the current block uses an intra sub-block partitioning mode. Here, the second syntax element is used to indicate the best partitioning type of the current block. For example, the encoding end determines the best partitioning type of the current block from horizontal partitioning and vertical partitioning according to the decision result, and determines the value of the second syntax element according to the best partitioning type. In some embodiments, the prediction parameter further includes a third syntax element, and the third syntax element is used to indicate whether the current block uses a second intra prediction mode for fusion prediction. Encoding the prediction parameter further includes: encoding the third syntax element in the case where it is determined according to the first syntax element that the current block uses an intra sub-block partitioning mode. It should be noted that the target sub-block encoded by using the encoding method provided in the embodiments of the present application may be one or more sub-blocks in the current block. Exemplarily, the target sub-block may be any sub-block in the current block, or may be some specific sub-blocks in the current block. Exemplarily, the specific sub-block may be other sub-blocks except the first sub-block. When the sub-block is the first sub-block, the intra prediction value of the first sub-block is determined based on the first intra prediction value. When the sub-block is other sub-blocks, weighted prediction is performed by using both the first intra prediction mode and the second intra prediction mode. By adopting the above technical solution, at the encoding end, when the current block uses an intra sub-block partitioning mode, the content characteristics of the reconstructed region are fully utilized, the second intra prediction mode is adaptively selected, and the sub-blocks are subjected to fusion prediction in combination with the first intra prediction mode, so as to improve the prediction accuracy of the intra sub-block partitioning mode, reduce the bit rate, and improve the encoding performance. In another embodiment of the present application, referring to FIG. 11, which shows a schematic flowchart of an encoding method and a decoding method provided in the embodiments of the present application. As shown in FIG. 11, whether at the encoding end or the decoding end, the method may include: S1101: Obtain the partitioning type of the current block; The variable intra_subpartitions_mode_flag is the first syntax element and is used to indicate whether the current block uses an intra sub-block partitioning mode. The variable intra_subpartitions_split_flag is the second syntax element and is used to indicate whether the partitioning type of the intra sub-block is horizontal or vertical. The variable IntraSubPartitionsSplitType specifies the specific partitioning type used for the current luma coding block, as shown in Table 1. The derivation process of IntraSubPartitionsSplitType is as follows: – If intra_subpartitions_mode_flag is equal to 0, then IntraSubPartitionsSplitType is set to 0. – Otherwise, IntraSubPartitionsSplitType is set to 1 + intra_subpartitions_split_flag. The variable NumIntraSubPartitions is used to specify the number of partitions of the sub-blocks into which the intra luma coding block is divided. The derivation process of NumIntraSubPartitions is as follows: – If IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT, then NumIntraSubPartitions is set to 1. – Otherwise, if one of the following conditions is true, then NumIntraSubPartitions is set to 2: – cbWidth is equal to 4 and cbHeight is equal to 8 – cbWidth is equal to 8 and cbHeight is equal to 4 – Otherwise, NumIntraSubPartitions is set to be equal to 4. S1102: Determine whether all sub-blocks of the current block have been completely reconstructed. If not, execute step S1103; if so, execute step S1108; The current block can be divided into NumIntraSubPartitions sub-blocks. Steps S1103 to S1107 will complete the prediction and reconstruction of each sub-block in the preset decoding order. This step determines whether all NumIntraSubPartitions sub-blocks of the current coding block have completed steps S1103 to S1107. If so, then perform step S1108; if not, then continue to perform the prediction and reconstruction of the next sub-block in steps S1103 to S1107. S1103: Determine whether it is the first sub-block. If not, execute step S1104; if so, execute step S1106; As shown in Figure 6, under horizontal partitioning, the number of sub - blocks is 4, that is, the variable intra_subpartitions_split_flag is 0, IntraSubPartitionsSplitType is 1, the variable NumIntraSubPartitions is 4, and the decoding order of the sub - blocks numbered from 0 to 3 is the decoding order of the sub - blocks, and the sub - block numbered 0 is the first sub - block. As shown in Figure 7, under vertical partitioning, the number of sub - blocks is 4, that is, the variable intra_subpartitions_split_flag is 1, IntraSubPartitionsSplitType is 2, the variable NumIntraSubPartitions is 4, and the decoding order of the sub - blocks numbered from 0 to 3 is the decoding order of the sub - blocks, and the sub - block numbered 0 is the first sub - block. S1104: Derive the second intra - prediction mode according to the reference sample values of the current sub - block; Exemplarily, the variable baseMode is the first intra - prediction mode, and the variable baseModeWeight is the first weight value. The variable fusionMode is the second intra - prediction mode. The array fusionModeWeight is the second weight value for fusionMode, and the variable NumFusionMode is the number of elements in fusionMode and fusionModeWeight. Method 1: Gradient derivation mode. Take the sub - block numbered 1 under horizontal partitioning as an example. Assume that the coordinate of the upper - left pixel position of the current sub - block relative to the upper - left pixel position of the image is (x, y), the width of the sub - block is Width, and the height is Height. Input: The luminance pixels of the sub - block in the reconstructed region of the current coding block are p[x][y], where x = 0...Width - 1, y = - 1.. - Height, that is, the sub - block region coded as 0. Among them, the origin [0][0] is the pixel coordinate of the upper - left corner within sub - block 0. If taking the sub - block numbered 2 as an example, the input includes, but is not limited to, the sub - block numbered 0, or the sub - block numbered 1, or the reconstructed values of the pixels within the sub - blocks numbered 0 and 1. If taking the sub - block numbered 0 as an example, the input includes, but is not limited to, the reconstructed values of the pixels within the left - adjacent block and / or the upper - adjacent block. Specifically, the gradient derivation process is as described above, and will not be elaborated here. Output: The second intra - prediction mode fusionMode derived by gradient, and the mode index range is [0, 66]. Method 2: Template derivation mode. Take the sub - block numbered 1 under horizontal partitioning as an example. Traverse the intra prediction modes, perform prediction on the sub-block area numbered 0, and calculate certain error values between the predicted value and the reconstructed value, including but not limited to Sum of Absolute Differences (SAD), Sum of Absolute Transformed Differences (SATD), Sum of Squared Errors (SSE), Mean Absolute Difference (MAD), Mean Absolute Error (MAE), Mean Squared Error (MSE), etc. Select NumFusionMode intra prediction modes through the error values and assign them to the array fusionMode. S1105: Determine the second intra prediction value according to the second intra prediction mode; S1106: Determine the first intra prediction value according to the first intra prediction mode; Furthermore, if the current block is not the first sub-block, determine the intra prediction value of the current block according to the first intra prediction value and the second intra prediction value; if the current block is the first sub-block, determine the intra prediction value of the current block according to the first intra prediction value. Exemplarily, determine the value of baseModeWeight and the values of each element in fusionModeWeight according to the preset weight allocation strategy. Perform weighted fusion on the first intra prediction value and the second intra prediction value according to baseModeWeight and fusionModeWeight to obtain the predicted value of the sub-block. Perform intra-frame weighted fusion prediction for other sub-blocks except the first sub-block. The specific process is as follows: Assume that predBase is the predicted value of baseMode, predFusion is the predicted value of fusionMode, and predFusion[i] is the predicted value of fusionMode[i]. Log2sumOfWeight is the base-2 logarithm of sumOfWeight. Then the calculation process of the predicted value pred of the intra-frame weighted fusion is as follows: The above calculation order and calculation method, etc., include but are not limited to the above forms. Subsequent processing of the predicted value pred includes but is not limited to performing Clip operations, etc. The calculation process of the predicted value pred of the intra-frame weighted fusion here can also be: Assume that predBase is the predicted value of baseMode, predFusion is the predicted value of fusionMode, predFusion[i] is the predicted value of fusionMode[i], predPlanar is the predicted value of Planar mode, and planarWeight is the weighted weight of Planar mode. Log2planarWeight is the base-2 logarithm of planarWeight. S1107: Reconstruction of sub-blocks; For the current sub-block, reconstruction is performed. At the encoding end: The residual information of the sub-block is transformed and quantized to obtain residual coefficients, and then the residual coefficients are inverse quantized, inverse transformed, and combined with the intra-predicted value of the sub-block to obtain the reconstructed value of the sub-block. At the decoding end: The bitstream is decoded to obtain the residual coefficients, the residual coefficients are inverse quantized, inverse transformed, and combined with the intra-predicted value of the sub-block to obtain the reconstructed value of the sub-block. S1108: Exit the ISP process. In the embodiments of the present application, while ensuring the bit-saving advantage of the ISP technology, the accuracy of ISP prediction can be improved. By analyzing the reconstructed sub-blocks, making full use of the content characteristics of the reconstructed sub-blocks, adaptively selecting the second intra-prediction mode of the subsequent sub-blocks, and using the weighted prediction method, it can better adapt to the blurred content and diverse textures in the image, improve the sub-block prediction accuracy, and also ensure the universality of the ISP technology. In another embodiment of the present application, based on the same inventive concept as the foregoing embodiment, referring to FIG. 12, which shows a schematic structural diagram of an encoder provided by the embodiments of the present application. As shown in FIG. 12, the encoder 120 may include a first determination unit 1201, a first prediction unit 1202, a decision unit 1203, and an encoding unit 1204; where: The first determination unit 1201 is configured to determine the first intra-prediction mode of the current block; The first prediction unit 1202 is configured to determine the first intra-predicted value of the target sub-block in the current block according to the first intra-prediction mode; The first determination unit 1201 is further configured to determine the second intra-prediction mode of the target sub-block based on the reference sample value of the target sub-block, where the second intra-prediction mode includes one or more intra-prediction modes; The first prediction unit 1202 is further configured to determine the second intra-predicted value of the target sub-block according to the second intra-prediction mode, where the second intra-predicted value includes one or more intra-predicted values determined according to one or more intra-prediction modes included in the second intra-prediction mode; The first prediction unit 1202 is further configured to determine the intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; and determine the reconstruction value of the target sub-block based on the intra prediction value of the target sub-block. The decision-making unit 1203 is configured to perform an encoding decision based on the reconstruction value of the target sub-block and determine the prediction parameters of the current block, where the prediction parameters include the first intra prediction mode. The encoding unit 1204 is configured to encode the prediction parameters and write the obtained encoded bits into the code stream. It can be understood that each functional unit of the encoder also executes the encoding method of any one of the foregoing embodiments. It can be understood that in the embodiments of the present application, a "unit" may be a part of a circuit, a part of a processor, a part of a program or software, etc. Of course, it may also be a module or non-modular. Moreover, the components in this embodiment can be integrated in one processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional module. If the integrated unit is implemented in the form of a software functional module and is not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the method of this embodiment. The foregoing storage medium includes: various media such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc that can store program codes. Therefore, the embodiments of the present application provide a computer-readable storage medium, which is applied to the encoder 120. The computer-readable storage medium stores a computer program, and when the computer program is executed by a first processor, the method of any one of the foregoing embodiments is implemented. The embodiments of the present application provide a computer-readable storage medium that stores the code stream generated by the encoding method as described above. Based on the composition of the encoder 120 and the computer-readable storage medium, refer to FIG. 13, which shows the specific hardware structure diagram of the encoder 130 provided in the embodiment of the present application. As shown in FIG. 13, the encoder 120 may include: a first communication interface 1301, a first memory 1302, and a first processor 1303; each component is coupled together through a first bus system 1304. It can be understood that the first bus system 1304 is used to realize the connection and communication between these components. In addition to the data bus, the first bus system 1304 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clear illustration, various buses are labeled as the first bus system 1304 in FIG. 13. Among them, The first communication interface 1301 is used for receiving and sending signals during the process of receiving and sending information with other external network elements; The first memory 1302 is used to store a computer program that can run on the first processor 1303; The first processor 1303 is used to execute the following when running the computer program: Determine the first intra prediction mode of the current block; According to the first intra prediction mode, determine the first intra prediction value of the target sub-block in the current block; Based on the reference sample value of the target sub-block, determine the second intra prediction mode of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; According to the second intra prediction mode, determine the second intra prediction value of the target sub-block, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; Based on the first intra prediction value and the second intra prediction value, determine the intra prediction value of the target sub-block; Based on the intra prediction value of the target sub-block, determine the reconstruction value of the target sub-block; Based on the reconstruction value of the target sub-block, make an encoding decision to determine the prediction parameters of the current block, where the prediction parameters include the first intra prediction mode; Encode the prediction parameters and write the obtained encoded bits into the bitstream. It can be understood that the first memory 1302 in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (DRRAM). The first memory 1302 of the systems and methods described in the present application is intended to include, but is not limited to, these and any other suitable types of memories. The first processor 1303 may be an integrated circuit chip with the ability to process signals. In the implementation process, each step of the above method can be completed by the integrated logic circuit in the hardware of the first processor 1303 or instructions in the form of software. The above-mentioned first processor 1303 may be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed and completed by the hardware decoding processor, or executed and completed by a combination of the hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, register, etc. This storage medium is located in the first memory 1302, and the first processor 1303 reads the information in the first memory 1302 and combines its hardware to complete the steps of the above method. It can be understood that these embodiments described in the present application can be implemented using hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions of the present application, or a combination thereof. For software implementation, the technology of the present application can be implemented by executing modules (such as procedures, functions, etc.) that perform the functions of the present application. The software code can be stored in a memory and executed by a processor. The memory can be implemented inside or outside the processor. Optionally, as another embodiment, the first processor 1303 is further configured to execute the method of any one of the foregoing embodiments when running a computer program. This embodiment provides an encoder. In this encoder, a target adjustment factor is used to adjust a virtual reference frame to improve the quality of the virtual reference frame, thereby improving the prediction accuracy of the current frame and enhancing the coding performance. In another embodiment of the present application, based on the same inventive concept as the foregoing embodiment, referring to FIG. 14, which shows a schematic structural diagram of a decoder 140 provided in an embodiment of the present application. As shown in FIG. 14, the decoder 140 may include: a decoding unit 1401, a second determination unit 1402, and a second prediction unit 1403; wherein: The decoding unit 1401 is configured to decode a bitstream and determine prediction parameters of a current block, where the prediction parameters include a first intra prediction mode. The second prediction unit 1403 is configured to determine a first intra prediction value of a target sub-block in the current block according to the first intra prediction mode. The second determination unit 1402 is configured to determine a second intra prediction mode of the target sub-block based on reference sample values of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes. The second prediction unit 1403 is further configured to determine a second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode. The second prediction unit 1403 is further configured to determine an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; and determine a reconstructed value of the target sub-block based on the intra prediction value of the target sub-block. It can be understood that each functional unit of the decoder also executes the decoding method of any one of the foregoing embodiments. Based on the composition of the decoder 140 and a computer-readable storage medium, referring to FIG. 15, which shows a specific hardware structural diagram of the decoder 140 provided in an embodiment of the present application. As shown in FIG. 15, the decoder 140 may include: a second communication interface 1501, a second memory 1502, and a second processor 1503; each component is coupled together through a second bus system 1504. It can be understood that the second bus system 1504 is used to implement connection communication between these components. The second bus system 1504 includes, in addition to a data bus, a power bus, a control bus, and a status signal bus. However, for the sake of clear illustration, all kinds of buses are labeled as the second bus system 1504 in FIG. 15. Wherein, The second communication interface 1501 is used for receiving and sending signals during the process of receiving and transmitting information with other external network elements. The second memory 1502 is used to store a computer program that can run on the second processor 1503. A second processor 1503, configured to execute, when running a computer program: Decode a bitstream, and determine prediction parameters of a current block, where the prediction parameters include a first intra prediction mode; Determine a first intra prediction value of a target sub-block in the current block according to the first intra prediction mode; Determine a second intra prediction mode of the target sub-block based on reference sample values of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; Determine a second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; Determine an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; Determine a reconstruction value of the target sub-block based on the intra prediction value of the target sub-block. Optionally, as another embodiment, the second processor 1503 is further configured to execute the method of any one of the foregoing embodiments when running a computer program. It can be understood that the second memory 1502 is similar in hardware function to the first memory 1302, and the second processor 1503 is similar in hardware function to the first processor 1303; details are not described herein again. This embodiment provides a decoder, in which a target adjustment factor is used to adjust a virtual reference frame to improve the quality of the virtual reference frame, thereby improving the prediction accuracy of the current frame and the decoding performance. In still another embodiment of the present application, referring to FIG. 16, which shows a schematic structural diagram of a codec system provided by an embodiment of the present application. As shown in FIG. 16, the codec system 160 may include an encoder 1601 and a decoder 1602. In the embodiment of the present application, the encoder 1601 may be the encoder of any one of the foregoing embodiments, and the decoder 1602 may be the decoder of any one of the foregoing embodiments. It should be noted that in the present application, the terms "include", "comprise" or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or elements inherent to such a process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including that element. The serial numbers of the embodiments of the present application above are only for description and do not represent the superiority or inferiority of the embodiments. The methods disclosed in several method embodiments provided by the present application can be arbitrarily combined without conflict to obtain new method embodiments. The features disclosed in several product embodiments provided by the present application can be arbitrarily combined without conflict to obtain new product embodiments. The features disclosed in several method or device embodiments provided by the present application can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments. As mentioned above, the above are only the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. Industrial Applicability The embodiments of the present application provide an encoding and decoding method, an encoder, a decoder, and a storage medium. Whether at the encoding end or the decoding end, according to the first intra prediction mode, determine the first intra prediction value of the target sub-block in the current block; based on the reference sample value of the target sub-block, determine the second intra prediction mode of the target sub-block; according to the second intra prediction mode, determine the second intra prediction value of the target sub-block; based on the first intra prediction value and the second intra prediction value, determine the intra prediction value of the target sub-block. In this way, when the current block uses the intra sub-block division mode, make full use of the content characteristics of the reconstructed area, adaptively select the second intra prediction mode, and combine the first intra prediction mode to perform fusion prediction on the sub-blocks, improving the prediction accuracy of the intra sub-block division mode, thereby further improving the encoding and decoding performance.

Claims

1. A decoding method, applied to a decoder, the method comprising: Decoding a bitstream to determine prediction parameters of a current block, wherein the prediction parameters include a first intra prediction mode; Determining a first intra prediction value of a target sub-block in the current block according to the first intra prediction mode; Determining a second intra prediction mode of the target sub-block based on reference sample values of the target sub-block, wherein the second intra prediction mode includes one or more intra prediction modes; Determining a second intra prediction value of the target sub-block according to the second intra prediction mode, wherein the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; Determining an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; Determining a reconstructed value of the target sub-block based on the intra prediction value of the target sub-block.

2. The method according to claim 1, wherein The prediction parameters further include a first syntax element for indicating whether the current block uses an intra sub-block partitioning mode; The decoding the bitstream to determine prediction parameters of the current block includes: Decoding the bitstream to determine the first syntax element of the current block; When it is determined according to the first syntax element that the current block uses an intra sub-block partitioning mode, decoding the bitstream to determine the first intra prediction mode.

3. The method according to claim 2, wherein, The prediction parameters further include a second syntax element for indicating a partitioning type of the current block; The decoding the bitstream to determine prediction parameters of the current block further includes: When it is determined according to the first syntax element that the current block uses an intra sub-block partitioning mode, decoding the bitstream to determine the second syntax element.

4. The method according to claim 3, wherein, The method further includes: Determining the partitioning type of the current block according to the second syntax element; Determining the number of sub-blocks partitioned in the current block according to the size of the current block; Determining a decoding order of sub-blocks in the current block according to the partitioning type and the number of sub-blocks of the current block; Determining the target sub-block in the current block according to the decoding order.

5. The method according to claim 2 or 3, wherein The prediction parameters further include a third syntax element for indicating whether the current block uses the second intra prediction mode for fusion prediction; The decoding the bitstream to determine prediction parameters of the current block further includes: When it is determined according to the first syntax element that the current block uses an intra sub-block partitioning mode, decoding the bitstream to determine the third syntax element.

6. The method according to claim 5, wherein, The method further includes: When it is determined according to the value of the third syntax element that the current block uses the second intra prediction mode for fusion prediction, determining the second intra prediction mode of the target sub-block based on reference sample values of the target sub-block; When it is determined according to the value of the third syntax element that the current block does not use the second intra prediction mode for fusion prediction, determining the intra prediction value of the target sub-block based on the first intra prediction value.

7. The method according to claim 1, wherein The reference sample values include: adjacent reconstructed sample values of the target sub-block.

8. The method according to claim 7, wherein, The method further includes: determining adjacent reconstructed sample values of the target sub-block from already reconstructed adjacent blocks of the target sub-block.

9. The method according to claim 8, wherein, The reconstructed neighboring blocks of the first sub-block in the current block include at least one of the following: the left neighboring block of the first sub-block, the upper neighboring block of the first sub-block, where the first sub-block is the first decoded sub-block determined according to the decoding order of the sub-blocks in the current block.

10. The method according to claim 8, wherein, The reconstructed neighboring blocks of other sub-blocks in the current block include: one or more reconstructed sub-blocks in the current block, where the other sub-blocks are one or more sub-blocks other than the first sub-block determined according to the decoding order of the sub-blocks in the current block.

11. The method according to claim 10, wherein, The reconstructed neighboring blocks of the other sub-blocks further include: other reconstructed neighboring blocks of the other sub-blocks.

12. The method according to any one of claims 1 to 11, wherein Determining the second intra prediction mode of the target sub-block based on the reference sample values of the target sub-block includes: Determining the prediction performance parameters of multiple candidate intra prediction modes based on the reference sample values using a first derivation mode; Determining one or more intra prediction modes included in the second intra prediction mode according to the prediction performance parameters.

13. The method according to claim 12, wherein, The method further includes: Decoding the bitstream to determine the first derivation mode.

14. The method according to claim 12, wherein, The first derivation mode includes a gradient derivation mode; The mode derivation method of the gradient derivation mode includes: Performing gradient analysis on the reference sample values to determine the gradient intensities of multiple candidate intra prediction modes in a first mode set; When the gradient intensities of the multiple candidate intra prediction modes include non-zero terms, determining at least one gradient intensity according to the order from large to small of the gradient intensities; Determining at least one mode index according to the gradient angles corresponding to the at least one gradient intensity; Determining one or more intra prediction modes included in the second intra prediction mode according to the at least one mode index.

15. The method according to claim 14, wherein, The mode derivation method of the gradient derivation mode further includes: When the gradient intensities of the multiple candidate intra prediction modes do not include non-zero terms, determining that the second intra prediction mode includes a first preset mode; When the gradient intensities of the multiple candidate intra prediction modes include non-zero terms and the second intra prediction mode includes a second preset mode, updating the gradient intensity of the second preset mode to a first gradient intensity and re-searching for other modes of the second intra prediction mode according to the updated gradient intensity.

16. The method according to claim 12, wherein The first derivation mode includes a template derivation mode; The mode derivation method of the template derivation mode includes: Predicting the reference sample values according to multiple candidate intra prediction modes in a second mode set to determine the predicted sample values of the reference sample values; Determining the error values of multiple candidate intra prediction modes in the second mode set according to the reference sample values and the predicted sample values; Determining one or more intra prediction modes included in the second intra prediction mode according to the order from small to large of the error values.

17. The method according to claim 1, wherein, The second intra prediction mode further includes a third preset mode.

18. The method according to any one of claims 1 to 17, wherein Determining the intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value includes: Performing weighted fusion on the first intra prediction value and the second intra prediction value to determine the intra prediction value of the target sub-block.

19. The method according to claim 18, wherein The method further includes: Based on a preset weight allocation strategy, determine a first weight value for the first intra prediction value and a second weight value for the second intra prediction value, where the second weight value includes one or more weight values corresponding to one or more intra prediction values included in the second intra prediction value.

20. The method according to claim 19, wherein, The weight allocation strategy includes: Add the prediction performance parameter of the first intra prediction mode and the prediction performance parameter of the second intra prediction mode to obtain a total prediction performance parameter; Divide the prediction performance parameter of the first intra prediction mode by the total prediction performance parameter to obtain a first coefficient; Divide the prediction performance parameter of the second intra prediction mode by the total prediction performance parameter to obtain a second coefficient; Perform weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value.

21. The method according to claim 20, wherein, The performing weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value includes: Calculate the product of the first coefficient and the total weight value to obtain the first weight value; Calculate the product of the second coefficient and the total weight value to obtain the second weight value; Or, The performing weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value includes: Divide the total weight value into a third weight value and a fourth weight value; Calculate the product of the first coefficient and the third weight value, and then add the fourth weight value to obtain the first weight value; Calculate the product of the second coefficient and the third weight value to obtain the second weight value.

22. The method according to claim 19, wherein, The weight allocation strategy includes: If the second intra prediction mode includes a first preset mode, determine the first weight value to be 1 and the second weight value to be 0; If the second intra prediction mode does not include the first preset mode, determine that the first weight value and the second weight value are equal.

23. The method according to claim 19, wherein, The method further includes: Save at least one of the first intra prediction mode, the second intra prediction mode, the first weight value, and the second weight value of the target sub-block.

24. An encoding method, applied to an encoder, the method includes: Determine a first intra prediction mode of a current block; According to the first intra prediction mode, determine a first intra prediction value of a target sub-block in the current block; Based on the reference sample value of the target sub-block, determine a second intra prediction mode of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; According to the second intra prediction mode, determine a second intra prediction value of the target sub-block, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; Based on the first intra prediction value and the second intra prediction value, determine an intra prediction value of the target sub-block; Based on the intra prediction value of the target sub-block, determine a reconstruction value of the target sub-block; Based on the reconstruction value of the target sub-block, make an encoding decision to determine a prediction parameter of the current block, where the prediction parameter includes the first intra prediction mode; Encode the prediction parameters and write the obtained encoded bits into the bitstream.

25. The method according to claim 24, wherein The prediction parameters further include a first syntax element for indicating whether the current block uses an intra sub-block partitioning mode. The encoding of the prediction parameters includes: Encoding the first syntax element; When it is determined according to the first syntax element that the current block uses the intra sub-block partitioning mode, encoding the first intra prediction mode.

26. The method according to claim 25, wherein, The prediction parameters further include a second syntax element for indicating the partitioning type of the current block. The encoding of the prediction parameters further includes: When it is determined according to the first syntax element that the current block uses the intra sub-block partitioning mode, encoding the second syntax element.

27. The method according to claim 25, wherein, The method further includes: Determining multiple candidate partitioning types of the current block; Determining the number of sub-block partitions in the current block according to the size of the current block; Determining multiple candidate encoding orders of sub-blocks in the current block according to the multiple candidate partitioning types and the number of partitions of the current block; Determining the target sub-block in the current block according to the candidate encoding order.

28. The method according to claim 25 or 26, wherein, The prediction parameters further include a third syntax element for indicating whether the current block uses the second intra prediction mode for fusion prediction. The encoding of the prediction parameters further includes: When it is determined according to the first syntax element that the current block uses the intra sub-block partitioning mode, encoding the third syntax element.

29. The method according to claim 28, wherein, The method further includes: When it is determined that the current block allows the use of the second intra prediction mode for fusion prediction, determining the second intra prediction mode of the target sub-block based on the reference sample values of the target sub-block; When it is determined that the current block does not allow the use of the second intra prediction mode for fusion prediction, determining the intra prediction value of the target sub-block based on the first intra prediction value.

30. The method according to claim 24, wherein, The reference sample values include: the adjacent reconstructed sample values of the target sub-block.

31. The method according to claim 30, wherein, The determination of the reference sample values of the target sub-block includes: Determining the adjacent reconstructed sample values of the target sub-block from the reconstructed adjacent blocks of the target sub-block.

32. The method according to claim 31, wherein The reconstructed adjacent blocks of the first sub-block in the current block include at least one of the following: the left adjacent block of the first sub-block, the upper adjacent block of the first sub-block, where the first sub-block is the first sub-block to be encoded determined according to the encoding order of sub-blocks in the current block.

33. The method according to claim 31, wherein The reconstructed adjacent blocks of other sub-blocks in the current block include: one or more reconstructed sub-blocks in the current block, where the other sub-blocks are one or more sub-blocks other than the first sub-block determined according to the candidate encoding order of sub-blocks in the current block.

34. The method according to claim 33, wherein The reconstructed adjacent blocks of the other sub-blocks further include: other adjacent blocks reconstructed by the other sub-blocks.

35. The method according to any one of claims 24 to 34, wherein The determination of the second intra prediction mode of the target sub-block based on the reference sample values of the target sub-block includes: Determining the prediction performance parameters of multiple candidate intra prediction modes based on the reference sample values using a first derivation mode; Determining one or more intra prediction modes included in the second intra prediction mode according to the prediction performance parameters.

36. The method according to claim 35, wherein The method further includes: Encode the first derivation mode and write the obtained encoded bits into the bitstream.

37. The method according to claim 35, wherein The first derivation mode includes a gradient derivation mode; The mode derivation method of the gradient derivation mode includes: Perform gradient analysis on the reference sample values to determine the gradient strengths of multiple candidate intra prediction modes in the first mode set; When the gradient strengths of the multiple candidate intra prediction modes contain non-zero terms, determine at least one gradient strength according to the order from largest to smallest of the gradient strengths; Determine at least one mode index according to the gradient angles corresponding to the at least one gradient strength; Determine one or more intra prediction modes included in the second intra prediction mode according to the at least one mode index.

38. The method according to claim 37, wherein, The mode derivation method of the gradient derivation mode further includes: When the gradient strengths of the multiple candidate intra prediction modes do not contain non-zero terms, determine that the second intra prediction mode includes a first preset mode; When the gradient strengths of the multiple candidate intra prediction modes contain non-zero terms and the second intra prediction mode includes a second preset mode, update the gradient strength of the second preset mode to a first gradient strength and re-search for other modes of the second intra prediction mode according to the updated gradient strength.

39. The method according to claim 35, wherein, The first derivation mode includes a template derivation mode; The mode derivation method of the template derivation mode includes: Predict the reference sample values according to multiple candidate intra prediction modes in the second mode set to determine the predicted sample values of the reference sample values; Determine the error values of multiple candidate intra prediction modes in the second mode set according to the reference sample values and the predicted sample values; Determine one or more intra prediction modes included in the second intra prediction mode according to the order from smallest to largest of the error values.

40. The method according to claim 24, wherein The second intra prediction mode further includes a third preset mode.

41. The method according to any one of claims 24 to 41, wherein Determining the intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value includes: Perform weighted fusion on the first intra prediction value and the second intra prediction value to determine the intra prediction value of the target sub-block.

42. The method according to claim 41, wherein, The method further includes: Based on a preset weight allocation strategy, determine a first weight value of the first intra prediction value and a second weight value of the second intra prediction value, where the second weight value includes one or more weight values corresponding to one or more intra prediction values included in the second intra prediction value.

43. The method according to claim 42, wherein The weight allocation strategy includes: Add the prediction performance parameters of the first intra prediction mode and the prediction performance parameters of the second intra prediction mode to obtain a total prediction performance parameter; Divide the prediction performance parameter of the first intra prediction mode by the total prediction performance parameter to obtain a first coefficient; Divide the prediction performance parameter of the second intra prediction mode by the total prediction performance parameter to obtain a second coefficient; Perform weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value.

44. The method according to claim 43, wherein, Performing weight allocation according to the first coefficient and the second coefficient to obtain the first weight value and the second weight value includes: Calculate the product of the first coefficient and the total weight value to obtain the first weight value; Calculate the product of the second coefficient and the total weight value to obtain the second weight value; Or, The weight allocation based on the first coefficient and the second coefficient to obtain the first weight value and the second weight value includes: Divide the total weight value into a third weight value and a fourth weight value; Calculate the product of the first coefficient and the third weight value, and then add the fourth weight value to obtain the first weight value; Calculate the product of the second coefficient and the third weight value to obtain the second weight value.

45. The method according to claim 42, wherein, The weight allocation strategy includes: If the intra prediction mode of the second frame includes a first preset mode, determine the first weight value as 1 and the second weight value as 0; If the intra prediction mode of the second frame does not include the first preset mode, determine that the first weight value and the second weight value are equal.

46. The method according to claim 42, wherein, The method further includes: saving at least one of the intra prediction mode of the first frame, the intra prediction mode of the second frame, the first weight value, and the second weight value of the target sub-block.

47. An encoder, including a first determination unit, a first prediction unit, a decision unit, and an encoding unit; wherein: The first determination unit is configured to determine the intra prediction mode of the current block; The first prediction unit is configured to determine the intra prediction value of the target sub-block in the current block according to the intra prediction mode of the first frame; prediction value; The first determination unit is further configured to determine the intra prediction mode of the target sub-block based on the reference sample value of the target sub-block, where the intra prediction mode of the second frame includes one or more intra prediction modes; The first prediction unit is further configured to determine the intra prediction value of the target sub-block according to the intra prediction mode of the second frame, where the intra prediction value of the second frame includes one or more intra prediction values determined according to one or more intra prediction modes included in the intra prediction mode of the second frame; The first prediction unit is further configured to determine the intra prediction value of the target sub-block based on the intra prediction value of the first frame and the intra prediction value of the second frame; and determine the reconstruction value of the target sub-block based on the intra prediction value of the target sub-block; The decision unit is configured to perform an encoding decision based on the reconstruction value of the target sub-block to determine the prediction parameter of the current block, where the prediction parameter includes the intra prediction mode of the first frame; The encoding unit is configured to encode the prediction parameter and write the obtained encoded bits into the code stream.

48. An encoder, including a first memory and a first processor; wherein: The first memory is used to store a computer program that can run on the first processor; The first processor is configured to execute the method according to any one of claims 24 to 46 when running the computer program.

49. A decoder, including a decoding unit, a second determination unit, and a second prediction unit; wherein: The decoding unit is configured to decode the code stream and determine the prediction parameter of the current block, where the prediction parameter includes the intra prediction mode of the first frame; The second prediction unit is configured to determine the intra prediction value of the target sub-block in the current block according to the intra prediction mode of the first frame; The second determination unit is configured to determine a second intra prediction mode of the target sub-block based on a reference sample value of the target sub-block, where the second intra prediction mode includes one or more intra prediction modes; The second prediction unit is further configured to determine a second intra prediction value of the target sub-block according to the second intra prediction mode, where the second intra prediction value includes one or more intra prediction values determined according to one or more intra prediction modes included in the second intra prediction mode; The second prediction unit is further configured to determine an intra prediction value of the target sub-block based on the first intra prediction value and the second intra prediction value; and determine a reconstructed value of the target sub-block based on the intra prediction value of the target sub-block.

50. A decoder, comprising a second memory and a second processor; wherein: The second memory is used to store a computer program that can run on the second processor; The second processor is configured to execute the method according to any one of claims 1 to 23 when running the computer program.

51. A computer-readable storage medium, wherein, The computer-readable storage medium stores a bitstream generated by the encoding method according to any one of claims 24 to 46.

52. A computer-readable storage medium, wherein, The computer-readable storage medium stores a computer program, and when the computer program is executed, it implements the method according to any one of claims 1 to 23, or implements the method according to any one of claims 24 to 46.

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