Encoding method, decoding method, code flow, encoder, decoder, and storage medium

Abstract

The modalities of this application disclose an encoding method, a decoding method, a code stream, an encoder, a decoder, and a storage medium; the decoding method comprises: parsing a code stream to determine the value of the first syntax identification information; if the first syntax identification information indicates that a current block uses a cross-component prediction export mode, parsing the code stream to determine the value of the second syntax identification information; if the second syntax identification information indicates that the current block uses a cross-component prediction export merge mode, parsing the code stream to determine at least one merge type identification value corresponding to the current block;Based on at least one fusion type identification value, determine at least one chrominance prediction mode corresponding to the current block; use the at least one chrominance prediction mode to perform an intra-chrominance prediction in the current block, in order to determine at least a first predicted value; use the cross-component prediction export mode to perform an intra-chrominance prediction in the current block, in order to determine a second predicted value; and, based on at least the first predicted value and the second predicted value, determine a predicted chrominance value corresponding to the current block; in this way, the prediction accuracy of a chrominance fusion mode can be improved, in such a way that the encoding and decoding efficiency can be improved.

Description

Coding and decoding method, code stream, encoder, decoder and storage medium Technical Field

[0001] The embodiments of the present application relate to the field of video coding and decoding technology, and in particular to a coding and decoding method, a bit stream, an encoder, a decoder, and a storage medium. Background Art

[0002] Based on the reference software test platform of the latest video coding standard H.266 / Versatile Video Coding (VVC), the Joint Video Experts Team (JVET) has proposed a new generation of reference software model, the Enhanced Compression Model (ECM).

[0003] In ECM, intra-frame prediction can include luma intra-frame prediction and chroma intra-frame prediction. Chroma intra-frame prediction includes a prediction method called a cross-component prediction fusion mode. This fusion mode combines the cross-component prediction fusion mode with the default cross-component prediction mode. This fusion method is relatively simple and fails to fully utilize the advantages of the fusion mode, resulting in low codec efficiency.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide a coding and decoding method, a code stream, an encoder, a decoder, and a storage medium, which can improve the prediction accuracy of the cross-component prediction-derived fusion mode, thereby improving the coding and decoding efficiency.

[0006] The technical solution of the embodiment of the present application can be implemented as follows:

[0007] In a first aspect, an embodiment of the present application provides a decoding method, applied to a decoder, the method comprising:

[0008] Parsing the code stream to determine the value of the first syntax identification information;

[0009] If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, parsing the bitstream to determine the value of the second syntax identification information;

[0010] If the second syntax identification information indicates that the current block uses cross-component prediction to derive a fusion mode, parsing the bitstream to determine at least one fusion type identification value corresponding to the current block;

[0011] Determining, according to the at least one fusion type identification value, at least one chroma prediction mode corresponding to the current block;

[0012] Performing chroma intra prediction on the current block using the at least one chroma prediction mode to determine at least one first prediction value;

[0013] Performing chroma intra prediction on the current block using a cross-component prediction derivation mode to determine a second prediction value;

[0014] Based on the at least one first prediction value and the second prediction value, a chrominance prediction value corresponding to the current block is determined.

[0015] In a second aspect, an embodiment of the present application provides an encoding method, applied to an encoder, the method comprising:

[0016] Determining a value of the first syntax identification information;

[0017] If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, determining a value of the second syntax identification information;

[0018] If the second syntax identification information indicates that the current block uses a cross-component prediction-derived fusion mode, then at least one chroma prediction mode corresponding to the current block is determined, and at least one fusion type identification value corresponding to the at least one chroma prediction mode is determined; the at least one fusion type identification value is used by the decoder to determine at least one first prediction value of the chroma intra-frame prediction of the current block based on the cross-component prediction-derived fusion mode.

[0019] In a third aspect, an embodiment of the present application provides a code stream, wherein the code stream is generated by bit encoding based on information to be encoded; wherein the information to be encoded includes at least one of the following:

[0020] The value of the first syntax identification information, the value of the second syntax identification information, and at least one fusion type identification value;

[0021] Among them, the first syntax identification information is used to indicate whether the current block uses a cross-component prediction derivation mode; the second syntax identification information is used to indicate whether the current block uses a cross-component prediction derivation fusion mode; and the at least one fusion type identification value is used to indicate at least one chroma prediction mode corresponding to the current block.

[0022] In a fourth aspect, an embodiment of the present application provides an encoder, comprising a first determining portion, configured to determine a value of first syntax identification information; if the first syntax identification information indicates that a current block uses a cross-component prediction derivation mode, determine a value of second syntax identification information;

[0023] The first determination part is also configured to determine at least one chroma prediction mode corresponding to the current block and determine at least one fusion type identification value corresponding to the at least one chroma prediction mode if the second syntax identification information indicates that the current block uses the cross-component prediction derived fusion mode; the at least one fusion type identification value is used by the decoder to determine at least one first prediction value of the chroma intra-frame prediction of the current block based on the cross-component prediction derived fusion mode.

[0024] In a fifth aspect, an embodiment of the present application provides an encoder, comprising a first memory and a first processor; wherein,

[0025] a first memory for storing a computer program capable of running on the first processor;

[0026] The first processor is configured to execute the encoding method described in the second aspect when running a computer program.

[0027] In a sixth aspect, an embodiment of the present application provides a decoder, the decoder comprising a parsing part, a second determination part and a second prediction part; wherein,

[0028] The parsing portion is configured to parse the bitstream to determine a value of first syntax identification information; if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, parse the bitstream to determine a value of second syntax identification information; if the second syntax identification information indicates that the current block uses the cross-component prediction derivation fusion mode, parse the bitstream to determine at least one fusion type identification value corresponding to the current block;

[0029] A second determining part is configured to determine at least one chroma prediction mode corresponding to the current block according to the at least one fusion type identification value;

[0030] The second prediction part is configured to use the at least one chroma prediction mode to perform chroma intra-frame prediction on the current block to determine at least one first prediction value; use the cross-component prediction derivation mode to perform chroma intra-frame prediction on the current block to determine a second prediction value; and determine the chroma prediction value corresponding to the current block based on the at least one first prediction value and the second prediction value.

[0031] In a seventh aspect, an embodiment of the present application provides a decoder, the decoder comprising a second memory and a second processor; wherein,

[0032] a second memory for storing a computer program capable of running on the second processor;

[0033] The second processor is configured to execute the decoding method as described in the first aspect when running a computer program.

[0034] In an eighth aspect, an embodiment of the present application provides a storage medium storing a computer program, which, when executed, implements the decoding method as described in the first aspect, or implements the encoding method as described in the second aspect.

[0035] An embodiment of the present application provides a coding and decoding method, a bitstream, an encoder, a decoder, and a storage medium. At a decoding end, the bitstream is parsed to determine the value of first syntax identification information; if the first syntax identification information indicates that the current block uses a cross-component prediction derivation mode, the bitstream is parsed to determine the value of second syntax identification information; if the second syntax identification information indicates that the current block uses a cross-component prediction derivation fusion mode, the bitstream is parsed to determine at least one fusion type identification value corresponding to the current block; based on the at least one fusion type identification value, at least one chroma prediction mode corresponding to the current block is determined; chroma intra-frame prediction is performed on the current block using the at least one chroma prediction mode to determine at least one first prediction value; chroma intra-frame prediction is performed on the current block using the cross-component prediction derivation mode to determine a second prediction value; and based on the at least one first prediction value and the second prediction value, a chroma prediction value corresponding to the current block is determined. In this way, when the current block uses the cross-component prediction derivation mode, it is further determined that the current block uses the cross-component prediction derivation fusion mode. At least one fusion type identification value corresponding to the current block can be further parsed from the code stream, and at least one chroma prediction mode corresponding to the current block is determined based on the at least one fusion type identification value. Then, at least one first prediction value predicted by the at least one chroma prediction mode is fused with the second prediction value predicted by the cross-component prediction derivation mode to determine the chroma prediction value corresponding to the current block. In other words, the fusion mode of the decoding end can be flexibly selected based on at least one fusion type identification value, providing a variety of options for the cross-component prediction derivation fusion mode, thereby improving the prediction accuracy of the cross-component prediction derivation fusion mode and thus improving decoding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG1 is a schematic diagram of a current block and adjacent reconstructed chroma pixels and reconstructed luminance pixels;

[0037] FIG2A is a schematic diagram of a linear model based on the CCLM model;

[0038] FIG2B is a schematic diagram of a linear model based on the CCLM-SLOPE model;

[0039] FIG3 is a schematic diagram of a multi-model based on the MMLM mode;

[0040] FIG4 is a schematic diagram of the spatial components of a convolution filter based on the CCCM mode;

[0041] FIG5 is a schematic diagram of a reference template area based on the CCCM mode;

[0042] FIG6 is a schematic diagram of candidate locations of spatially adjacent blocks;

[0043] FIG7 is a schematic diagram of candidate locations of non-adjacent blocks in a spatial domain;

[0044] FIG8 is a schematic block diagram of an encoder provided in an embodiment of the present application;

[0045] FIG9 is a block diagram of a decoder according to an embodiment of the present application;

[0046] FIG10 is a schematic diagram of a network architecture of a coding and decoding system provided in an embodiment of the present application;

[0047] FIG11 is a flowchart diagram 1 of a decoding method provided in an embodiment of the present application;

[0048] FIG12 is a second flow chart of a decoding method provided in an embodiment of the present application;

[0049] FIG13 is a schematic diagram of a flow chart of an encoding method provided in an embodiment of the present application;

[0050] FIG14 is a schematic diagram of the structure of an encoder provided in an embodiment of the present application;

[0051] FIG15 is a schematic diagram of a specific hardware structure of an encoder provided in an embodiment of the present application;

[0052] FIG16 is a schematic diagram of the structure of a decoder provided in an embodiment of the present application;

[0053] FIG17 is a schematic diagram of a specific hardware structure of a decoder provided in an embodiment of the present application;

[0054] FIG18 is a schematic diagram of the composition structure of a coding and decoding system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0055] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present application, the implementation of the embodiments of the present application is described in detail below with reference to the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present application.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0057] In the following description, reference is made to “some embodiments”, which describes a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0058] It should also be pointed out that the terms "first\second\third" involved in the embodiments of the present application are only used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described here can be implemented in an order other than that illustrated or described here.

[0059] With the goal of exploring the next generation of digital video compression technology, a new generation of reference software model, the Enhanced Compression Model (ECM), was developed based on the reference software test platform (VVC Test Model, VTM) of the latest video coding standard H.266 / VVC. Currently, video compression technology is also based on traditional block-based codecs, which can include multiple modules, such as block partitioning, intra-frame prediction, inter-frame prediction, transformation, quantization, entropy coding, loop and post-processing filtering, etc. The embodiments of this application mainly improve the prediction part to enhance the coding performance of ECM.

[0060] Here, the prediction part can include a variety of technologies, including luminance prediction mode and chrominance prediction mode. For chrominance intra-frame prediction, it can be divided into two types: cross-component prediction mode and non-cross-component prediction mode. Among them, the non-cross-component prediction mode usually includes planar mode, direct current (DC) mode, decoder side intra mode derivation (DIMD) mode, etc. For the cross-component linear model (CCLM) prediction mode, the central idea of ​​the CCLM prediction mode is to reduce cross-component redundancy and perform cross-component prediction, mainly using the reconstructed luminance pixels of the same coding block to construct the predicted value of the chrominance pixel. The linear relationship is shown in the following formula (1): pred C (i,j)=a·rec L '(i,j)+b (1)

[0061] Among them, pred C (i, j) represents the chroma prediction pixel of the current block, rec L'(i,j) represents the downsampled reconstructed luminance pixels of the current block; a and b are called linear model parameters. Among them, a is a scaling parameter and b is an offset parameter. a and b can be derived from the adjacent chrominance pixels and luminance pixels. Since the linear model here can be calculated at both the encoding end and the decoding end, it does not need to be written into the bitstream. For example, Figure 1 shows a schematic diagram of the current block and the adjacent reconstructed chrominance pixels and reconstructed luminance pixels in the CCLM mode. As shown in Figure 1, the circles filled with grids represent the reference pixels that are adjacent to the current block and have been reconstructed, which may include the left reference pixels and the upper reference pixels. In addition, N represents the side length corresponding to the chrominance component of the current block, and 2N represents the side length corresponding to the luminance component of the current block.

[0062] In addition to using all upper reference pixels and left reference pixels to jointly calculate the parameters of the linear model, there are two other ways to calculate the model parameters, that is, CCLM has two other modes, called CCLM-T and CCLM-L modes, as follows:

[0063] In CCLM-T mode, only the upper reference pixels are used to calculate the linear model parameters;

[0064] In CCLM-L mode, only the reference pixels on the left are used to calculate the linear model parameters.

[0065] In order to further improve the coding efficiency of CCLM, many improvements have been made to CCLM in ECM, including the slope-based CCLM model (CCLM_SLOPE), multi-model linear model (Multi-Model Linear Model, MMLM), convolutional cross-component model (Convolutional Cross-Component Model, CCCM), gradient linear model (Gradient Linear Model, GLM), etc. The following is a brief introduction to some linear models.

[0066] In CCLM_SLOPE, the calculated linear model parameters can be adjusted as follows: a'=a+u,b'=bu*yr (2)

[0067] Here, the updated linear model parameters a' and b' are used to calculate the predicted pixels. Through this improvement, the mapping function is tilted or rotated around the point with a luminance value of yr. Wherein yr is generally the average value of the reference luminance pixels. For example, Figure 2A is a schematic diagram of a linear model based on the CCLM mode, and Figure 2B is a schematic diagram of a linear model based on the CCLM-SLOPE mode. Wherein, the horizontal axis represents the reconstructed luminance information (Y), and the vertical axis represents the chrominance prediction information (Cb / Cr); the model parameters of Figure 2A are a and b, and the model parameters of Figure 2B are a' and b', and the model parameters a' and b' of Figure 2B can be obtained by adjusting the model parameters a and b.

[0068] In CCLM, there is only one linear model between the luminance and chrominance of the same coding block. In MMLM, multiple models can be provided for the same coding block. Adjacent luminance and chrominance pixels are divided into different categories according to the classification threshold, and the pixels in each category are used to calculate different model parameters. For example, Figure 3 is a schematic diagram of a multi-model based on the MMLM mode. As shown in Figure 3, here, adjacent reference pixels are classified according to the classification threshold, and two linear models can be constructed: the model parameters of the first linear model are α1=2, β1=1; the model parameters of the second linear model are α2=1 / 2, β2=-1.

[0069] For the cross-component prediction mode of CCCM, the predicted pixels are obtained through a set of convolution filters. For example, a 7-tap convolution filter usually contains 5 spatial components as shown in Figure 4, as well as a nonlinear term and a bias term. The generation of the predicted pixels can be shown in formula (3): pred C (i,j)=c0C+c1N+c2S+c3E+c4W+c5P+c6B (3)

[0070] Where C represents the luminance pixel at pixel position (i, j), and N, S, W, and E represent the pixels above, below, left, and right of the corresponding pixel, respectively. The nonlinear term P is expressed as the power of 2 of the center luminance sample C, scaled to the sample value range of the content. B is the bias term, set to the midpoint of the chrominance value. That is, B = midVal. The value of P can be determined using formula (4) as follows: P = (C*C+midVal)>>bitDepth (4)

[0071] Here, bitDepth represents the bit depth, and the value of midVal is determined according to the bit depth value. For example, when the bit depth is 10, the value of midVal is 512.

[0072] In formula (3), the coefficients of the convolution filter, such as c0 to c6, are determined by adjacent reconstructed pixels. Unlike CCLM, the reference template area of ​​CCCM can be as shown in Figure 5, including 6 rows and 6 columns of reconstructed pixels around the current block, as well as extended areas in the upper right and lower left. The oblique line area outside the reference template area in Figure 5 represents the spatial component expansion part used in the convolution filter. The coefficients of the convolution filter can be determined by minimizing the mean-square error (MSE) between the predicted and reconstructed chrominance samples in the reference template area. Among them, MSE minimization can be achieved by calculating the autocorrelation matrix of the luminance input and the cross-correlation vector between the luminance input and the chrominance output.

[0073] There are many derivative variations of the cross-component prediction mode based on the convolution model, including GLM. Similar to CCLM, CCCM can choose to use different reference template area shapes, that is, there are CCCM-T and CCCM-L modes. Similarly, CCCM can also choose to use multiple parameter models, that is, the Multi-Model Convolutional Cross-Component Model (MM-CCCM) mode. In the MM-CCCM mode, the current input sample determines the specific convolution filter used according to the threshold to obtain the final predicted pixel value.

[0074] It should also be understood that for the cross-component prediction derivation mode, in the various cross-component linear model prediction modes described above, all cross-component model parameters (ccmParam) are calculated from adjacent reconstructed luma and chroma pixels. Based on this, a cross-component prediction derivation mode (CCMerge) is proposed. In this mode, the ccmParam of the current block is directly inherited from the reconstructed block, rather than being calculated. The flag ccmMrgFlag indicates whether the current block uses cross-component prediction derivation mode. If the flag ccmMrgFlag is true, meaning the current block is in CCMerge mode, a model parameter (ccmParam) list is created for the current block. This list can be represented as ccmList[NUM_LMC_MERGE_CANDS]. This list is populated with existing ccmParams from both spatially adjacent and non-adjacent candidate blocks. By default, the upper limit of the number of candidates in this list, NUM_LMC_MERGE_CANDS, is 6. When the above process does not fill the list, it can be filled according to the preset default parameters, and the specific model parameters to be used are indicated by the candidate index cclmMrgIdx.

[0075] In some embodiments, the candidate list is populated as follows:

[0076] Step 1: Spatial neighbor candidates.

[0077] First, the spatial adjacent blocks are checked. The positions of the adjacent blocks can be shown in FIG6 , and the checking order is B1->A1->B0->A0->B2.

[0078] Step 2: Spatial non-adjacent candidates.

[0079] After examining all spatially adjacent blocks, consider spatially non-adjacent blocks. Their positional relationship is shown in Figure 7, where each point represents a non-adjacent block and indicates the top-left corner of that non-adjacent block. Note that the grid in Figure 7 is merely a representation of pixel coordinates and does not represent a specific block division.

[0080] Step 3: Default parameter CCLM candidate.

[0081] If the list is not full, then after checking the spatially adjacent candidates and non-adjacent candidates, consider the CCLM candidate with the default scaling parameter. The default scaling parameters are {0, 1 / 8, -1 / 8, 2 / 8, -2 / 8, 3 / 8}. If CCLM type candidates exist in the previous construction process, the scaling parameter a of the first CCLM type candidate added is first Adjust and add to the candidate list, the scaling parameters in this case are {0,a first +{1 / 8,-1 / 8,2 / 8,-2 / 8,3 / 8,-3 / 8,4 / 8,-4 / 8,5 / 8,-5 / 8,6 / 8}}.

[0082] For model parameters, the inheritance rules are as follows:

[0083] 1) When inheriting a CCLM candidate, the scaling and offset parameters are inherited.

[0084] 2) When inheriting an MMLM candidate, the scaling parameters and classification thresholds are inherited.

[0085] 3) When inheriting a CCCM candidate, all convolution parameters and classification thresholds are inherited.

[0086] 4) When inheriting a GLM candidate, if the GLM is in 3-parameter mode, all gradient indices and model parameters are inherited; otherwise, if the GLM is in 2-parameter mode, only the scaling parameters are inherited, and the offset parameters need to be recalculated.

[0087] 5) When the chroma fusion mode is inherited, the MMLM parameters derived from the cross-component prediction part are inherited and used as candidates.

[0088] 6) When inheriting a CCMerge candidate, the inheritance method depends on the candidate mode it inherits.

[0089] In the above-mentioned cross-component prediction derivation mode, the predicted value calculated according to the derived cross-component prediction model is used as the final predicted pixel value. In the fusion mode of the cross-component prediction derivation mode, the above-mentioned predicted value needs to be weightedly fused with the predicted value calculated by the MM-CCCM mode to obtain the final predicted value. The default MM-CCCM mode calculates a set of cross-component prediction models based on the reconstructed luminance values ​​and reconstructed chrominance values ​​adjacent to the current block, and calculates the predicted value based on the cross-component prediction model and the pixel value of the luminance block corresponding to the current block, and weightedly fused with the predicted value generated by the cross-component prediction derivation mode to obtain the final predicted value.

[0090] It can be seen that the current fusion mode of the cross-component prediction derivation mode only performs weighted fusion on the prediction value obtained by the derived cross-component model and the prediction value obtained by the default MM-CCCM. The fusion mode is relatively simple and fails to give full play to the role of the fusion mode, thereby reducing the encoding and decoding efficiency.

[0091] Based on this, an embodiment of the present application provides a coding and decoding method. For the coding end, at least one chroma prediction mode to be fused with the cross-component prediction derivation mode can be determined based on the coding cost, and at least one fusion type identification value corresponding to the at least one chroma prediction mode is sent to the decoding end. When the decoding end determines to use the cross-component prediction derivation fusion mode for the current block, it further parses at least one fusion type identification value from the bitstream, performs chroma intra-frame prediction based on at least one chroma prediction mode corresponding to the at least one fusion type identification value, and fuses the obtained prediction value with the prediction value of the cross-component prediction derivation mode as the chroma prediction value corresponding to the current block. In this way, the fusion mode of the decoding end can be flexibly selected by using at least one fusion type identification value, providing a variety of options for the cross-component prediction derivation fusion mode, which can improve the prediction accuracy of the cross-component prediction derivation fusion mode, and thus improve the coding and decoding efficiency.

[0092] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0093] Referring to Figure 8, which shows a schematic block diagram of the composition of an encoder provided in an embodiment of the present application. As shown in Figure 8, the 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, and a decoded image cache unit 110, etc., wherein 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 by dividing the coding tree unit (CTU). Then, the residual pixel information obtained after intra-frame or inter-frame prediction is transformed by the transformation and quantization unit 101, 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 to perform intra-frame prediction on 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 to encode the video coding block; the motion compensation unit 104 and the motion estimation unit 105 are used to perform inter-frame prediction coding on 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 the process of generating a motion vector, which can estimate the motion of the video coding block. The motion compensation unit 104 then calculates the motion vector 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 configured to provide the selected intra-frame prediction data to the encoding unit 109, and the motion estimation unit 105 also sends the calculated motion vector data to the encoding unit 109. In addition, the inverse transform and inverse quantization unit 106 is configured to reconstruct the video coding block and reconstruct a residual block in the pixel domain. The reconstructed residual block is subjected to the filter control analysis unit 107 and the filtering unit 108 to remove the block effect artifacts. The reconstructed residual block is then added to a predictive block in the frame of the decoded image buffer unit 110 to generate a reconstructed video coding block. The encoding unit 109 is configured to encode various coding parameters and quantized transform coefficients. In the CABAC-based coding algorithm, the context content can be based on adjacent coding blocks and can be used to encode information indicating the determined intra-frame prediction mode, and output the code stream of the video signal. The decoded image buffer unit 110 is configured to store the reconstructed video coding block for prediction reference. As the video image encoding proceeds, new reconstructed video encoding blocks are continuously generated, and these reconstructed video encoding blocks are stored in the decoded image buffer unit 110 .

[0094] Refer to Figure 9, which shows a block diagram of a decoder provided by an embodiment of the present application. As shown in Figure 9, the decoder 200 includes a decoding unit 201, an inverse transform and inverse quantization unit 202, an intra-frame prediction unit 203, a motion compensation unit 204, a filtering unit 205 and a decoded image cache unit 206, etc., wherein the decoding unit 201 can implement header information decoding and CABAC decoding, and the filtering unit 205 can implement deblocking filtering and SAO filtering. After the input video signal is encoded in Figure 8, the code stream of the video signal is output; the code stream is input to the decoder 200, and first passes through the decoding unit 201 to obtain the decoded transform coefficient; the transform coefficient is processed by the inverse transform and inverse quantization unit 202 to generate a residual block in the pixel domain; the intra-frame prediction unit 203 can be used to generate prediction data for the current video decoding block based on the determined intra-frame prediction mode and the data of the previously decoded block from the current frame or picture; the motion compensation unit 204 is to determine the prediction information for the video decoding block by analyzing the motion vector and other associated syntax elements, and use The prediction information is used to generate a predictive block for the video decoding block being decoded; a decoded video block is formed by summing the residual block from the inverse transform and inverse quantization unit 202 with the corresponding predictive block generated by the intra-frame prediction unit 203 or the motion compensation unit 204; the decoded video signal passes through the filtering unit 205 to remove blocking artifacts, thereby improving video quality; the decoded video block is then stored in the decoded image buffer unit 206, which stores reference images used for subsequent intra-frame prediction or motion compensation, and is also used for outputting the video signal, thereby obtaining the restored original video signal.

[0095] Furthermore, the embodiment of the present application also provides a network architecture of a coding and decoding system including an encoder and a decoder, wherein Figure 10 shows a schematic diagram of a network architecture of a coding and decoding system provided by an embodiment of the present application. As shown in Figure 10, the network architecture includes one or more electronic devices 13 to 1N and a communication network 01, wherein 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 coding 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., and the embodiment of the present application is not specifically limited. Here, the decoder or encoder described in the embodiment of the present application can be the above-mentioned electronic device.

[0096] It should be noted that the method of the embodiment of the present application is mainly applied to the prediction part shown in Figure 8 and the prediction part shown in Figure 9. In other words, the embodiment of the present application can be applied to both the encoder and the decoder, and can even be applied to both the encoder and the decoder simultaneously, but the embodiment of the present application is not specifically limited to this. In addition, the prediction part here can include the intra-frame prediction part and the inter-frame prediction part.

[0097] It should also be noted that on the encoding side, the "current block" specifically refers to the coding block currently undergoing chroma prediction; on the decoding side, the "current block" specifically refers to the decoding block currently undergoing chroma prediction. Here, the current block can be a coding unit (CU), a coding tree unit (CTU), or even a prediction unit (PU) or a transform unit (TU), without specific limitations here.

[0098] In one embodiment of the present application, referring to FIG11 , a flowchart of a decoding method provided by an embodiment of the present application is shown. As shown in FIG11 , the method may include:

[0099] S101: Parse the code stream to determine the value of the first syntax identification information.

[0100] S102: If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, parse the bitstream to determine the value of the second syntax identification information.

[0101] It should be noted that the decoding method of the embodiment of the present application is applied to a decoder. Furthermore, the decoding method may specifically refer to a chroma prediction method. Within the chroma prediction mode, this primarily addresses technical improvements to the cross-component prediction derivation mode within the chroma intra-frame prediction mode. More specifically, improvements may be made to the cross-component prediction derivation fusion mode within the cross-component prediction derivation mode, thereby improving ECM coding performance.

[0102] It should also be noted that, in an embodiment of the present application, the first syntax identification information is used to indicate whether the current block uses the cross-component prediction derivation mode (CCMerge). In some embodiments, if the value of the first syntax identification information is a first value, it is determined that the first syntax identification information indicates that the current block does not use the cross-component prediction derivation mode; if the value of the first syntax identification information is a second value, it is determined that the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode. In an embodiment of the present application, the first value and the second value are not the same. Here, the first value and the second value can be in parameter form or in digital form. Specifically, the first syntax identification information here can be a parameter written in the profile or the value of a flag, which is not specifically limited here.

[0103] Exemplarily, the first syntax identification information can be represented by ccmMrgFlag. The first value can be set to 0, and the second value can be set to 1; alternatively, the first value can be set to false, and the second value can be set to true. If ccmMrgFlag is 0, it indicates that the current block does not use the cross-component prediction derivation mode. If ccmMrgFlag is 1, it indicates that the current block uses the cross-component prediction derivation mode.

[0104] That is to say, in an embodiment of the present application, if the value of the first syntax identification information is the first value, then it can be determined that the current block does not use the cross-component prediction derivation mode. In some embodiments, when the first syntax identification information indicates that the current block does not use the cross-component prediction derivation mode, such as when the value of the first syntax identification information is the first value, the chroma intra-frame prediction is performed on the current block through the cross-component prediction mode to determine the chroma prediction value corresponding to the current block. The cross-component prediction mode in the embodiment of the present application may at least include: any one of: a cross-component linear model prediction mode, an MMLM mode, a convolutional cross-component model mode, a GLM mode, and a chroma fusion mode. Among them, the cross-component linear model prediction mode includes: at least one of the CCLM mode, the CCLM-T mode, and the CCLM-L mode; the convolutional cross-component model mode includes: at least one of the CCCM mode, the CCCM-T mode, and the CCCM-T mode. The specific selection is made according to the actual situation and is not limited in the embodiment of the present application.

[0105] In the embodiment of the present application, if the value of the first syntax identification information is the second value, it can be determined that the current block uses the cross-component prediction derivation mode, and the decoder further parses the code stream to determine the value of the second syntax identification information.

[0106] S103: If the second syntax identification information indicates that the current block uses cross-component prediction to derive a merging mode, parse the bitstream to determine at least one merging type identification value corresponding to the current block.

[0107] In an embodiment of the present application, the second syntax identification information is used to indicate whether the current block uses cross-component prediction to derive a fusion mode. In some embodiments, if the value of the second syntax identification information is a third value, it is determined that the second syntax identification information indicates that the current block does not use cross-component prediction to derive a fusion mode; if the value of the second syntax identification information is a fourth value, it is determined that the second syntax identification information indicates that the current block uses cross-component prediction to derive a fusion mode. In an embodiment of the present application, the third value and the fourth value are not the same. The third value may be the same as or different from the first value, and the fourth value may be the same as or different from the second value. Here, the third value and the fourth value may be in parameter form or in digital form. Specifically, the second syntax identification information here may be a parameter written in the profile or the value of a flag, which is not specifically limited here.

[0108] For example, the second syntax identification information can be represented by ccpMergeFusionFlag. The third value can be set to 0, and the fourth value can be set to 1; alternatively, the third value can be set to false, and the fourth value can be set to true. If ccpMergeFusionFlag is 0, it indicates that the current block does not use cross-component prediction to derive the fusion mode. If cclmMrgFlag is 1, it indicates that the current block uses cross-component prediction to derive the fusion mode.

[0109] In some embodiments, when the second syntax identification information indicates that the current block does not use the cross-component prediction derivation fusion mode, such as when ccpMergeFusionFlag is 0, the decoder performs chroma intra-frame prediction on the current block through the cross-component prediction derivation mode to determine the chroma prediction value corresponding to the current block.

[0110] That is, in an embodiment of the present application, when the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, and the second syntax identification information indicates that the current block uses the cross-component prediction derivation fusion mode, it can be determined that the cross-component prediction derivation fusion mode is used for chroma intra prediction of the current block. The decoder further parses the bitstream to determine at least one fusion type identification value corresponding to the current block. The index identification value is used to indicate at least one chroma prediction mode used for chroma intra prediction of the current block, so as to weightedly fuse the prediction results of the at least one chroma prediction mode with the prediction results of the cross-component prediction derivation mode.

[0111] S104: Determine at least one chroma prediction mode corresponding to the current block according to at least one fusion type identification value.

[0112] In an embodiment of the present application, the decoder and the encoder may agree on a preset correspondence between a fusion type identifier value and a chroma prediction mode. The preset correspondence between the fusion type identifier value and the chroma prediction mode includes: at least one preset fusion type identifier value corresponding to at least one preset chroma prediction mode. In this manner, the decoder can determine, based on the at least one fusion type identifier value, the at least one chroma prediction mode corresponding to the current block within the preset correspondence.

[0113] Exemplarily, at least one preset fusion type identifier value in digital form may be used to identify at least one preset chroma prediction mode. The MM-CCCM mode and the derived mode (DM) mode are preset as at least one preset chroma prediction mode, and the preset fusion type identifier value corresponding to the MM-CCCM mode is 0, and the preset fusion type identifier value corresponding to the DM mode is 1. When the decoder parses the bitstream and obtains at least one fusion type identifier value of 1, it determines to use the DM mode as at least one chroma prediction mode and fuses the prediction results with the cross-component prediction derived mode.

[0114] In an embodiment of the present application, at least one preset chroma mode may include a cross-component prediction mode and a non-cross-component prediction mode. In some embodiments, at least one preset chroma prediction mode includes at least one of: a cross-component linear model prediction mode, an MMLM mode, a convolutional cross-component model mode, a GLM mode, a DIMD mode, and a DM mode. The specific selection is made according to the actual situation and is not limited in the embodiment of the present application.

[0115] S105: Perform chroma intra prediction on the current block using at least one chroma prediction mode to determine at least one first prediction value.

[0116] S106: Perform chroma intra prediction on the current block using the cross-component prediction derivation mode to determine a second prediction value.

[0117] S107: Determine a chroma prediction value corresponding to the current block based on at least one first prediction value and a second prediction value.

[0118] In an embodiment of the present application, the decoder performs chroma intra prediction on the current block using each of at least one chroma prediction mode, determines a first prediction value corresponding to each chroma prediction mode, and thereby determines at least one first prediction value. The decoder performs chroma intra prediction on the current block using the CCMerge mode, and determines a second prediction value corresponding to the CCMerge mode. The decoder performs a weighted fusion based on the at least one first prediction value and the second prediction value to determine the chroma prediction value corresponding to the current block.

[0119] In some embodiments, the decoder may perform weighted summation on at least one first prediction value and a second prediction value according to at least two preset weights to determine a weighted sum value; determine a shift factor according to at least two preset weights, and shift the weighted sum value according to the shift factor to determine a chroma prediction value.

[0120] For example, taking a first prediction value and a second prediction value as an example, the fusion can be achieved by formula (5), as follows: pred final =(w1*pred ccpMerge +w2*predfusionMode)>>shift (5)

[0121] Wherein, at least one weight is w1 and w2, shift represents a shift factor, and satisfies the relationship w1+w2=2shift. For example, w1 and w2 can be the default value 2, and shift is 2. pred ccpMerge It represents the second prediction value corresponding to the cross-component prediction derivation mode, and predfusionMode represents the first prediction value corresponding to the chroma prediction mode determined according to the fusion type identifier value.

[0122] It should be noted that multiple chroma prediction modes can be determined based on multiple fusion type identification values. Similar to formula (5), multiple second prediction values ​​corresponding to the multiple chroma prediction modes and the first prediction value can be weighted summed and shifted using multiple weights to determine the chroma prediction value corresponding to the current block. In other words, the embodiments of the present application can achieve the fusion of multiple chroma prediction modes.

[0123] Exemplarily, the fusion type identification value may be at least one value corresponding to the fusion type flag in the bitstream. The fusion type flag may be ccpMergeFusionMode. The at least one preset chroma prediction mode may include a first preset chroma prediction mode and a second preset chroma prediction mode. The preset fusion type identification value corresponding to the first preset chroma prediction mode is 0; the preset fusion type identification value corresponding to the second preset chroma prediction mode is 1. When the value of the second syntax identification information ccpMergeFusionFlag is 1, that is, the second syntax identification information indicates that the fusion mode is derived using cross-component prediction for the current block, it is necessary to further select a corresponding fusion scheme based on the value of ccpMergeFusionMode. If the value of ccpMergeFusionMode is 0, the first preset chroma prediction mode is selected to generate the first prediction value, which is then fused with the second prediction value of the CCMerge mode to generate the final chroma prediction value. If the value of ccpMergeFusionMode is 1, the second preset chroma prediction mode is selected to generate the first prediction value, which is then fused with the second prediction value of the CCMerge mode to generate the final chroma prediction value.

[0124] When the value of the second syntax identification information ccpMergeFusionFlag is 0, it indicates that the cross-component prediction is not used to derive the fusion mode, and there is no need to decode the flag bit of ccpMergeFusionMode.

[0125] In some possible embodiments, the first preset chroma prediction mode may be an MM-CCCM mode, and the second preset chroma prediction mode may be an MMLM mode. An example of the embodiment of the present application acting on cross-component prediction to derive a fusion mode is as follows:

[0126] When the decoder parses and finds that the value of ccpMergeFusionFlag of the current block is 1, at least one chroma prediction mode for fusing the prediction result with the CCMerge mode is determined according to the value of the flag ccpMergeFusionMode.

[0127] If the value of ccpMergeFusionMode is 0, the chroma prediction mode for fusion with the CCMerge mode is set to MM-CCCM. Chroma intra prediction is performed according to the steps of the MM-CCCM mode to determine the first prediction value. The first prediction value is weightedly fused with the second prediction value generated by the CCMerge mode to obtain the chroma prediction value for the current block.

[0128] If the value of ccpMergeFusionMode is 1, the chroma prediction mode for fusion with the CCMerge mode is set to MMLM. Chroma intra prediction is performed according to the steps of the MMLM mode to determine a first prediction value. The first prediction value is weightedly fused with the second prediction value generated by the CCMerge mode to obtain the chroma prediction value for the current block.

[0129] In some other possible embodiments, the first preset chroma prediction mode may be the MM-CCCM mode, and the second preset chroma prediction mode may be the DIMD mode. An example of the embodiment of the present application acting on cross-component prediction to derive a fusion mode is as follows:

[0130] When the decoder parses and finds that the value of ccpMergeFusionFlag of the current block is 1, at least one chroma prediction mode for fusing the prediction result with the CCMerge mode is determined according to the value of the flag ccpMergeFusionMode.

[0131] If the value of ccpMergeFusionMode is 0, the chroma prediction mode for fusion with the CCMerge mode is set to MM-CCCM. Chroma intra prediction is performed according to the steps of the MM-CCCM mode to determine the first prediction value. The first prediction value is weightedly fused with the second prediction value generated by the CCMerge mode to obtain the chroma prediction value for the current block.

[0132] If the value of ccpMergeFusionMode is 1, the chroma prediction mode for fusion with the CCMerge mode is set to DIMD mode. Following the steps of the DIMD mode, the corresponding intra-frame prediction angle mode is derived to generate the first prediction value. The first prediction value is weightedly fused with the second prediction value generated by the CCMerge mode to obtain the chroma prediction value for the current block.

[0133] It can be understood that when the current block uses the cross-component prediction derivation mode, the decoder further determines that the current block uses the cross-component prediction derivation fusion mode, and can further parse out at least one fusion type identification value corresponding to the current block from the code stream, determine at least one chroma prediction mode corresponding to the current block based on the at least one fusion type identification value, and then use at least one first prediction value predicted by the at least one chroma prediction mode to fuse with the second prediction value predicted by the cross-component prediction derivation mode to determine the chroma prediction value corresponding to the current block. In other words, the fusion mode of the decoding end can be flexibly selected based on at least one fusion type identification value, providing a variety of options for cross-component derivation fusion mode prediction, thereby improving the prediction accuracy of the cross-component prediction derivation fusion mode and thus improving decoding efficiency.

[0134] In some embodiments, based on FIG11 , as shown in FIG12 , after S101 and before S102 , S201 - S203 may be further performed as follows:

[0135] S201: If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, then based on the template area of ​​the current block, chroma intra-frame prediction is performed according to the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode respectively, and the first generation value corresponding to the cross-component prediction derivation mode and the second generation value corresponding to the cross-component prediction derivation fusion mode are determined.

[0136] In an embodiment of the present application, if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, the template area corresponding to the current block can be determined. Exemplarily, T rows and T columns (T is an integer not less than 1, such as T is equal to 3) of pixels in the reconstructed area around the current block can be used as the template area. It can be understood that the template area includes the reconstructed blocks around the current block. In the template area, the decoder performs chroma intra prediction based on the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode, respectively.

[0137] In an embodiment of the present application, the encoder uses the cross-component prediction derivation mode to predict on the template area, and determines the first generation value corresponding to the cross-component prediction derivation mode based on the prediction value corresponding to the cross-component prediction derivation mode and the reconstructed value of the prediction block in the template area.

[0138] In an embodiment of the present application, for the process of performing intra-chroma prediction on a template area based on a cross-component prediction derived fusion mode, the decoder can perform prediction based on the template area through each preset chroma prediction mode in at least one preset chroma prediction mode to obtain a prediction value corresponding to each preset chroma prediction mode. The decoder fuses the prediction value corresponding to each preset chroma prediction mode with the prediction value corresponding to the above-mentioned cross-component prediction derived mode to obtain a prediction value corresponding to each fusion scheme. Here, each fusion scheme refers to a combination of each preset chroma prediction mode and a cross-component prediction derived mode. The decoder compares the prediction value corresponding to each fusion scheme with the reconstructed value of the prediction block in the template area to determine the second-generation value corresponding to the cross-component prediction derived fusion mode.

[0139] S202: Determine whether the current block uses cross-component prediction to derive a fusion mode based on the first generation value and the second generation value.

[0140] In an embodiment of the present application, the decoder can determine whether the current block uses the cross-component prediction-derived fusion mode based on the comparison of the first-generation value and the second-generation value. For example, when the second-generation value is less than the second-generation value, it means that the prediction effect of the cross-component prediction-derived fusion mode is better, and the decoder determines that the current block uses the cross-component prediction-derived fusion mode. When the first-generation value is less than the second-generation value, it means that the prediction effect of the cross-component prediction-derived mode is better, and the decoder determines that the current block does not use the cross-component prediction-derived fusion mode.

[0141] S203: If it is determined that the current block uses the cross-component prediction to derive the merging mode, parse the bitstream to determine at least one merging type identification value corresponding to the current block.

[0142] In an embodiment of the present application, if the decoder determines that the current block uses a cross-component prediction derived fusion mode, it can further parse the code stream to determine at least one fusion type identification value, and then implement the methods in S104-S107 above to realize the chroma intra-frame prediction under the cross-component prediction derived fusion mode provided in the embodiment of the present application.

[0143] It can be understood that the embodiment of the present application adaptively selects whether to use cross-component prediction to derive the fusion mode based on the template matching method, without the need to transmit the second syntax identification information in the code stream to determine whether to use cross-component prediction to derive the fusion mode, thereby improving the bit rate and encoding and decoding efficiency.

[0144] In some embodiments, when the current block uses cross-component prediction to derive a fusion mode, the decoder may determine at least one chroma prediction mode corresponding to the current block based on chroma intra prediction on a template region of the current block.

[0145] In an embodiment of the present application, determining that the current block uses cross-component prediction to derive a fusion mode may include: determining that the current block uses cross-component prediction to derive a fusion mode according to an indication of the second syntax identification information in the bitstream; or determining that the current block uses cross-component prediction to derive a fusion mode according to the template area-based prediction method in the above S201-S202.

[0146] In some embodiments, for the case where the current block is determined to use a cross-component prediction-derived fusion mode according to the indication of the second syntax identification information in the bitstream, the decoder can determine the template area corresponding to the current block, and use the cross-component prediction-derived mode and at least one preset chroma prediction mode to perform prediction on the template area to determine the cost value corresponding to each fusion scheme. The process is consistent with the corresponding process description in S201-S202 and is not repeated here. The decoder can determine at least one fusion scheme with a cost value less than the cost value corresponding to each fusion scheme based on the cost value corresponding to each fusion scheme, and then determine at least one chroma prediction mode based on the preset chroma prediction mode in at least one fusion scheme.

[0147] In some embodiments, for the case where the current block is determined to use cross-component prediction to derive a fusion mode according to the template area-based prediction method in S201-S202 above, the decoder can directly use the cost value corresponding to each fusion scheme that has been predicted to determine at least one fusion scheme with a cost value smaller than the cost value, and then determine at least one chroma prediction mode based on the preset chroma prediction mode in at least one fusion scheme.

[0148] It can be understood that the embodiment of the present application adaptively selects at least one chroma prediction mode to be merged with the cross-component prediction derivation mode based on the template matching method, without passing the fusion type identification value in the code stream to determine which chroma prediction modes are used to merge with the cross-component prediction derivation mode, thereby improving the bit rate and encoding and decoding efficiency.

[0149] In some embodiments, the decoder performs chroma intra prediction on the current block using a cross-component prediction derivation mode, and the process of determining the second prediction value may include:

[0150] Determine the index identification value of the current block and construct a parameter candidate list of the current block; determine the model parameters of the current block according to the parameter candidate list and the index identification value; and determine a second prediction value based on the model parameters and the reconstructed luminance pixels corresponding to the current block.

[0151] In an embodiment of the present application, the index identification value is used to specify the model parameters corresponding to the current block in the parameter candidate list of the current block.

[0152] In some embodiments, if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, the decoder can determine the index identification value of the current block by parsing the bitstream. Exemplarily, the index identification value can be cclmMrgIdx.

[0153] In some embodiments, the idxNonLocalCCP flag bit may also be used as an index identification value. The value of idxNonLocalCCP is an integer between 0 and 12, with a minimum of 0 and a maximum of 12. When the value of idxNonLocalCCP is 0, the current block does not use the cross-component prediction derivation mode; when the value of idxNonLocalCCP is not 0, the model parameters of the current block are obtained from the constructed parameter candidate list according to the value of idxNonLocalCCP. Exemplarily, the model parameters may be ccmList[idxNonLocalCCP-1].

[0154] In the embodiment of the present application, the process of constructing the parameter candidate list of the current block may include:

[0155] Determine adjacent blocks of the current block; if at least one of the adjacent blocks uses a cross-component prediction mode or a cross-component prediction derivation mode, determine model parameters of the at least one block to obtain at least one set of first candidate model parameters; and fill the at least one set of first candidate model parameters into a parameter candidate list.

[0156] It should be noted that, in the embodiment of the present application, adjacent blocks may include: blocks that are spatially adjacent to the current block, and / or blocks that are temporally adjacent to the current block. That is, the adjacent blocks here may be spatially adjacent blocks, or they may be temporally adjacent blocks. Among them, the spatially adjacent blocks are located in the same frame as the current block, and the temporally adjacent blocks are located in different frames from the current block. For example, in the case of inter-frame prediction, the adjacent blocks at this time may refer to temporally adjacent blocks located on the reference frame.

[0157] It should also be noted that, taking spatial adjacency as an example, the positions of adjacent blocks of the current block can be as shown in Figure 6, and the inspection order can be B1->A1->B0->A0->B2, and then at least one set of first candidate model parameters is determined in this order.

[0158] Furthermore, after filling at least one group of first candidate model parameters into the parameter candidate list, if the parameter candidate list is in an unfilled state, then in some embodiments, constructing the parameter candidate list for the current block may also include: determining the non-adjacent blocks of the current block; if at least one block in the non-adjacent blocks uses a cross-component prediction mode or a cross-component prediction derivation mode, determining the model parameters of at least one block to obtain at least one group of second candidate model parameters; and continuing to fill at least one group of second candidate model parameters into the parameter candidate list.

[0159] It should also be noted that in this embodiment of the present application, the number of candidates in the parameter candidate list is represented by NUM_LMC_MERGE_CANDS. By default, the value of NUM_LMC_MERGE_CANDS is set to 12. If the number of first candidate model parameters is less than 12, it indicates that the parameter candidate list is not full; in this case, it is necessary to determine at least one set of second candidate model parameters based on the non-adjacent blocks of the current block, and then continue to fill the at least one set of second candidate model parameters into the parameter candidate list. For example, the spatial non-adjacent block positions of the current block can be shown in Figure 7.

[0160] Furthermore, after filling at least one set of second candidate model parameters into the parameter candidate list, if the parameter candidate list is in an unfilled state, then in some embodiments, constructing the parameter candidate list for the current block may also include: determining at least one set of third candidate model parameters from the historical parameter candidate list; and continuing to fill at least one set of third candidate model parameters into the parameter candidate list.

[0161] It should be noted that in the embodiment of the present application, the decoder maintains a historical parameter candidate list, which contains the most recently used model parameters (ccmParam), and resets the table at the beginning of each CTU row. If the current list is not full after including spatially adjacent and non-adjacent candidates, the ccmParam in the historical parameter candidate list is added to the parameter candidate list.

[0162] Furthermore, after filling at least one group of second candidate model parameters into the parameter candidate list, or after filling at least one group of third candidate model parameters into the parameter candidate list, if the parameter candidate list is in an unfilled state, then in some embodiments, constructing the parameter candidate list for the current block may also include: determining at least one group of fourth candidate model parameters based on preset parameter information; and continuing to fill at least one group of fourth candidate model parameters into the parameter candidate list.

[0163] It should be noted that, in the embodiment of the present application, the preset parameter information may include at least a preset value of the first model parameter, and the preset value of the first model parameter is at least one of the following: 0, 1 / 8, -1 / 8, 2 / 8, -2 / 8, 3 / 8.

[0164] It should also be noted that, in some embodiments, the model parameters of the current block may include a first model parameter and a second model parameter, wherein the first model parameter may be used to indicate a scaling parameter when the current block uses the cross-component prediction mode or the cross-component prediction derivation mode, and the second model parameter may be used to indicate an offset parameter when the current block uses the cross-component prediction mode or the cross-component prediction derivation mode.

[0165] That is, after constructing a parameter candidate list based on neighboring blocks and non-neighboring blocks of the current block, if the constructed parameter candidate list is not full, CCLM candidates with default scaling parameters may be considered. The default scaling parameters may be {0, 1 / 8, -1 / 8, 2 / 8, -2 / 8, 3 / 8}. It should be noted that these default scaling parameters may be added to the parameter candidate list in the order of 0, 1 / 8, -1 / 8, 2 / 8, -2 / 8, and 3 / 8.

[0166] It can also be understood that in an embodiment of the present application, the cross-component prediction mode may include at least one of the following: a cross-component linear model prediction mode, an MMLM mode, a convolution cross-component model mode, a GLM mode, and a chroma fusion mode. Among them, the cross-component linear model prediction mode includes: at least one of the CCLM mode, the CCLM-T mode, and the CCLM-L mode; the convolution cross-component model mode includes: at least one of the CCCM mode, the CCCM-T mode, and the CCCM-T mode. That is to say, the inheritance mode here can be any cross-component prediction mode among the cross-component linear model prediction mode, the MMLM mode, the convolution cross-component model mode, the GLM mode, the chroma fusion mode, and the CCMerge mode, etc., and there is no specific limitation on this.

[0167] In some embodiments, determining the model parameters of the current block based on the parameter candidate list and the index identification value may include: determining a set of candidate model parameters corresponding to the index identification value in the parameter candidate list; determining the inheritance mode of the current block and the corresponding candidate model parameters based on a set of candidate mode parameters; and determining the model parameters of the current block based on the inheritance mode of the current block and the candidate model parameters.

[0168] Furthermore, in some embodiments, determining the model parameters of the current block according to the inheritance mode of the current block and the candidate model parameters may include:

[0169] If the inheritance mode of the current block is the cross-component linear model prediction mode, the first model parameter and the second model parameter in the candidate model parameters are determined as the model parameters of the current block, that is, the first model parameter and the second model parameter in the candidate model parameters are determined to be inherited by the current block; wherein the first model parameter is used to indicate the scaling parameter of the cross-component prediction mode or the cross-component prediction derivation mode, such as a in formula (1); the second model parameter is used to indicate the offset parameter of the cross-component prediction mode or the cross-component prediction derivation mode, such as b in formula (1);

[0170] If the inheritance mode of the current block is the MMLM mode, the first model parameter and the classification threshold in the candidate model parameters are determined as the model parameters of the current block, that is, the current block is determined to inherit the first model parameter and the classification threshold in the candidate model parameters;

[0171] If the inheritance mode of the current block is CCCM mode, the convolution parameters and classification thresholds in the candidate model parameters are determined as the model parameters of the current block, that is, the convolution parameters and classification thresholds in the candidate model parameters are determined to be inherited by the current block;

[0172] If the inheritance mode of the current block is the GLM mode, then when the GLM mode is the three-parameter mode, the gradient index value, the first model parameter, and the second model parameter in the candidate model parameters are determined as the model parameters of the current block; or, when the GLM mode is the two-parameter mode, the model parameters of the current block are determined based on the first model parameter in the candidate model parameters. That is, when the GLM mode is the three-parameter mode, it is determined that the current block inherits the gradient index value, the first model parameter, and the second model parameter in the candidate model parameters; or, when the GLM mode is the two-parameter mode, it is determined that the current block inherits the first model parameter in the candidate model parameters;

[0173] If the inheritance mode of the current block is the chroma fusion mode, then when the chroma fusion mode is the chroma fusion derivation mode, determining the prediction mode inherited by the current block, and determining the model parameters of the current block according to the prediction mode inherited by the current block and the candidate model parameters; or, when the chroma fusion mode is not the chroma fusion derivation mode, determining that the current block uses the MMLM mode, and determining that the current block inherits the first model parameter and the classification threshold among the candidate model parameters;

[0174] If the inheritance mode of the current block is the CCMerge mode, the prediction mode inherited by the current block is determined, and the model parameters of the current block are determined according to the prediction mode inherited by the current block and the candidate model parameters.

[0175] Specifically, in the embodiment of the present application, a cross-component model parameter source is added, which can provide multiple options for cross-component prediction and derivation modes. Among them, the inheritance rule can be as follows:

[0176] 1) When inheriting CCLM mode, the scaling and offset parameters are inherited.

[0177] 2) When inheriting the MMLM mode, the scaling parameters and classification thresholds will be inherited.

[0178] 3) When inheriting CCCM mode, all convolution parameters and classification thresholds are inherited.

[0179] 4) When inheriting the GLM mode, if the GLM is in 3-parameter mode, all gradient indices and model parameters are inherited; otherwise, if the GLM is in 2-parameter mode, only the scaling parameters are inherited, and the offset parameters need to be recalculated.

[0180] 5) When the chroma fusion mode is inherited, the MMLM parameters derived from the cross-component prediction part are inherited and used as candidates.

[0181] 6) When inheriting the CCMerge mode, the inheritance method depends on the candidate mode it inherits.

[0182] It is also understood that in the embodiments of the present application, a separate set of rules can be used for the size and construction process of the parameter candidate list, rather than the shared rules of the cross-component prediction derivation mode, and this is not specifically limited here. In this way, after determining the model parameters of the current block according to the above-mentioned inheritance rules, the target prediction value of the current block can be further determined.

[0183] In another embodiment of the present application, referring to FIG13 , a schematic flow chart of an encoding method provided by an embodiment of the present application is shown. As shown in FIG13 , the method may include:

[0184] S301: Determine a value of first syntax identification information.

[0185] It should be noted that the encoding method of the embodiment of the present application is applied to an encoder. In addition, the encoding method may specifically refer to a chroma prediction method. Among them, in the chroma prediction mode, this mainly focuses on technical improvements to the cross-component prediction derivation mode in the chroma intra-frame prediction mode. More specifically, it may be to improve the fusion mode of the cross-component prediction derivation in the cross-component prediction derivation mode, thereby improving the coding performance of ECM.

[0186] It should also be noted that, in the embodiment of the present application, the first syntax identification information is used to indicate whether the current block uses the cross-component prediction derivation mode. In addition, the value of the first syntax identification information is different, and the mode indicated here is also different accordingly.

[0187] In some embodiments, in some embodiments, if the value of the first syntax identification information is a first value, it is determined that the first syntax identification information is used to indicate that the current block does not use the cross-component prediction derivation mode; if the value of the first syntax identification information is a second value, it is determined that the first syntax identification information is used to indicate that the current block uses the cross-component prediction derivation mode. In an embodiment of the present application, the first value and the second value are different. Here, the first value and the second value can be in parameter form or in digital form. Specifically, the first syntax identification information here can be a parameter written in the profile or the value of a flag, which is not specifically limited here.

[0188] Exemplarily, the first syntax identification information can be represented by cclmMrgFlag. The first value can be set to 0, and the second value can be set to 1; alternatively, the first value can be set to false, and the second value can be set to true. If cclmMrgFlag is 0, it indicates to the decoder that the current block does not use the cross-component prediction derivation mode. If cclmMrgFlag is 1, it indicates to the decoder that the current block uses the cross-component prediction derivation mode.

[0189] In an embodiment of the present application, the encoder can perform chroma intra-frame prediction on the current block through the cross-component prediction derivation mode and at least one cross-component prediction mode, respectively, to obtain the prediction value corresponding to the cross-component prediction derivation mode and at least one prediction value corresponding to the at least one cross-component prediction mode. The encoder can determine whether to use the cross-component prediction derivation mode for the current block by comparing the prediction value corresponding to the cross-component prediction derivation mode with at least one prediction value corresponding to the at least one cross-component prediction mode, and then determine the first syntax identification information. Among them, the cross-component prediction mode can include at least: any one of: a cross-component linear model prediction mode, an MMLM mode, a convolutional cross-component model mode, a GLM mode, and a chroma fusion mode.

[0190] Furthermore, in some embodiments, the method may further include: encoding the value of the first syntax identification information, and writing the obtained coded bits into the bitstream.

[0191] It should be noted that, in an embodiment of the present application, the encoding end writes the value of the first syntax identification information into the bitstream, so that the decoding end can directly determine the value of the first syntax identification information by decoding the bitstream, and then determine whether the current block uses the cross-component prediction derivation mode.

[0192] In some embodiments, the encoder determines that the current block does not use the cross-component prediction derivation mode by comparing the coding costs between the cross-component prediction derivation mode and at least one cross-component prediction mode, and then determines the prediction value corresponding to the cross-component prediction mode with the smaller coding cost in the at least one cross-component prediction mode as the chrominance prediction value corresponding to the current block.

[0193] S302: If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, determine a value of the second syntax identification information.

[0194] In this embodiment of the present application, if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, that is, the encoder determines to use the cross-component prediction derivation mode for the current block. The encoder then further determines whether the current block uses the cross-component prediction derivation fusion mode through coding cost comparison, and further determines the value of the second syntax identification information.

[0195] In an embodiment of the present application, the second syntax identification information is used to indicate whether the current block uses cross-component prediction to derive a fusion mode. In some embodiments, if the value of the second syntax identification information is the third value, it is determined that the second syntax identification information is used to indicate that the current block does not use cross-component prediction to derive a fusion mode; if the value of the second syntax identification information is the fourth value, it is determined that the second syntax identification information is used to indicate that the current block uses cross-component prediction to derive a fusion mode. In an embodiment of the present application, the third value and the fourth value are not the same. The third value may be the same as or different from the first value, and the fourth value may be the same as or different from the second value. Here, the third value and the fourth value may be in parameter form or in digital form. Specifically, the second syntax identification information here may be a parameter written in the profile or the value of a flag, which is not specifically limited here.

[0196] Exemplarily, the second syntax identification information can be represented by ccpMergeFusionFlag. The third value can be set to 0, and the fourth value can be set to 1; alternatively, the third value can be set to false, and the fourth value can be set to true. If ccpMergeFusionFlag is 0, it indicates to the decoder that the current block does not use cross-component prediction to derive the fusion mode. If cclmMrgFlag is 1, it indicates to the decoder that the current block uses cross-component prediction to derive the fusion mode.

[0197] In an embodiment of the present application, the encoder can determine whether to use the cross-component prediction derivation mode for the current block by comparing the coding costs of the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode, and then determine the second syntax identification information.

[0198] Furthermore, in some embodiments, the method may further include: encoding the value of the second syntax identification information, and writing the obtained coded bits into the bitstream.

[0199] In some embodiments, when the encoder determines through coding cost comparison that the current block does not use the cross-component prediction derived fusion mode, the prediction value of the chroma intra-frame prediction of the current block using the cross-component prediction derived mode is determined as the chroma prediction value corresponding to the current block.

[0200] S303: If the second syntax identification information indicates that the current block uses cross-component prediction to derive a fusion mode, determine at least one chroma prediction mode corresponding to the current block, and determine at least one fusion type identification value corresponding to the at least one chroma prediction mode.

[0201] In an embodiment of the present application, if the second syntax identification information indicates that the current block uses the cross-component prediction-derived fusion mode, it indicates that the encoder determines to use the cross-component prediction-derived fusion mode for the current block by comparing the coding costs of the cross-component prediction-derived mode and the cross-component prediction-derived fusion mode. The process of the encoder comparing the coding costs of the cross-component prediction-derived mode and the cross-component prediction-derived fusion mode may include:

[0202] Perform chroma intra-frame prediction on the current block through the cross-component prediction derivation mode to determine the prediction value corresponding to the cross-component prediction derivation mode; perform chroma intra-frame prediction on the current block through at least one preset chroma prediction mode to determine at least one prediction value corresponding to the at least one preset chroma prediction mode; fuse each prediction value of the at least one prediction value with the prediction value corresponding to the cross-component prediction derivation mode to obtain at least one fused prediction value; determine at least one coding cost based on the at least one fused prediction value and the chroma value of the current block.

[0203] In which, the encoder can determine the first chroma prediction value corresponding to each preset chroma prediction mode in at least one preset chroma prediction mode; determine the encoding cost corresponding to each preset chroma prediction mode based on the first chroma prediction value corresponding to each preset chroma prediction mode and the chroma value of the current block, thereby determining at least one encoding cost.

[0204] Here, since at least one coding cost is obtained by fusing each prediction value with the prediction value corresponding to the cross-component prediction derivation mode, that is, at least one coding cost corresponds to at least one preset chroma prediction mode. The decoder can determine the coding cost corresponding to the cross-component prediction derivation fusion mode based on the at least one coding cost. Exemplarily, the minimum value of the at least one coding cost can be determined as the coding cost corresponding to the cross-component prediction derivation fusion mode, and then by comparing the coding cost corresponding to the cross-component prediction derivation fusion mode with the coding cost of the cross-component prediction derivation mode, it is determined whether the current block uses the cross-component prediction derivation fusion mode.

[0205] In an embodiment of the present application, when the encoder determines a cross-component prediction-derived fusion mode, at least one chroma prediction mode may be determined from at least one preset chroma prediction mode based on at least one calculated coding cost. For example, the preset chroma prediction mode corresponding to the top n coding costs with the lowest coding cost may be determined as the at least one chroma prediction mode. n is an integer not less than 1.

[0206] In an embodiment of the present application, an encoder may determine, based on at least one chroma prediction mode, at least one fusion type identification value corresponding to a current block from a preset correspondence between fusion type identification values ​​and chroma prediction modes; wherein the preset correspondence between fusion type identification values ​​and chroma prediction modes includes: at least one preset fusion type identification value corresponding to at least one preset chroma prediction mode. In this way, at a decoder side, the at least one fusion type identification value may be used to determine at least one first prediction value for chroma intra-frame prediction of the current block in a fusion mode derived based on cross-component prediction.

[0207] In an embodiment of the present application, at least one preset chroma mode may include a cross-component prediction mode and a non-cross-component prediction mode. In some embodiments, at least one preset chroma prediction mode includes at least one of: a cross-component linear model prediction mode, an MMLM mode, a convolution cross-component model mode, a GLM mode, a DIMD mode, and a DM mode. Among them, the cross-component linear model prediction mode includes: at least one of a CCLM mode, a CCLM-T mode, and a CCLM-L mode; the convolution cross-component model mode includes: at least one of a CCCM mode, a CCCM-T mode, and a CCCM-T mode. The specific selection is made according to the actual situation, and the embodiment of the present application is not limited.

[0208] In some embodiments, after S303, the encoder may further determine at least one first chroma prediction value corresponding to at least one chroma prediction mode based on the first chroma prediction value corresponding to each preset chroma prediction mode obtained during the encoding cost comparison process; perform chroma intra-frame prediction on the current block using the cross-component prediction derivation mode to determine a second prediction value; determine the chroma prediction value corresponding to the current block based on the at least one first prediction value and the second prediction value, thereby completing the encoder-side cross-component prediction derivation fusion mode processing and obtaining the chroma prediction value corresponding to the current block. Furthermore, the encoder determines the residual corresponding to the current block based on the chroma prediction value corresponding to the current block and the chroma value of the current block; generates encoding information corresponding to the current block based on the residual, the first syntax identification information, the second syntax identification information, and at least one fusion type identification value, and writes it into the bitstream.

[0209] It can be understood that when the encoder determines that the cross-component prediction derivation mode is used in the current block, it further determines that the current block uses the cross-component prediction derivation fusion mode, and determines at least one chroma prediction mode fused with the cross-component prediction derivation mode based on the coding cost, determines at least one fusion type identification value corresponding to the at least one chroma prediction mode and sends it to the decoder, so that the fusion mode of the decoding end can be flexibly specified according to the at least one fusion type identification value, providing a variety of options for the cross-component prediction derivation fusion mode, thereby improving the accuracy of the chroma intra-frame prediction, and thus improving the coding efficiency.

[0210] In some embodiments, if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, then based on the template area of ​​the current block, chroma intra-frame prediction is performed according to the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode, respectively, to determine the first generation value corresponding to the cross-component prediction derivation mode and the second generation value corresponding to the cross-component prediction derivation fusion mode; based on the first generation value and the second generation value, determine whether the current block uses the cross-component prediction derivation fusion mode; if it is determined that the current block uses the cross-component prediction derivation fusion mode, determine at least one fusion type identification value corresponding to the current block.

[0211] In this embodiment of the present application, the encoder can also adaptively select whether to use cross-component prediction to derive the fusion mode based on the template matching method, without transmitting the second syntax identification information in the bitstream to determine whether to use cross-component prediction to derive the fusion mode, thereby improving the bit rate and coding efficiency. The process is consistent with the process described in S201-S203 of the decoder and will not be repeated here.

[0212] In some embodiments, when the current block uses cross-component prediction to derive a merge mode, at least one merge type identification value corresponding to the current block is determined according to chroma intra prediction on a template region of the current block.

[0213] In the embodiment of the present application, the encoder can also adaptively select at least one chroma prediction mode and cross-component prediction derived mode for fusion based on the template matching method, without transmitting the fusion type identification value in the bitstream to determine which chroma prediction mode to use for fusion with the cross-component prediction derived mode, so as to improve the bit rate and coding efficiency. The process is consistent with the same process described in the decoder and will not be repeated here.

[0214] In short, the embodiment of the present application mainly provides a new fusion scheme for the cross-component prediction derivation fusion mode. In the embodiment of the present application, at least one chrominance prediction mode used for fusion with the cross-component prediction derivation mode in the cross-component prediction derivation fusion mode can be specified by at least one fusion type identification value, thereby providing multiple options for the fusion scheme and improving the efficiency of intra-frame prediction of encoding and decoding. For example, Table 1 shows the test results of the embodiment of the present application. It can be seen from this that the embodiment of the present application can improve encoding and decoding efficiency, thereby improving encoding and decoding performance.

[0215] Table 1

[0216] In the embodiments of the present application, the specific implementation of the aforementioned embodiments is elaborated in detail through the above embodiments. It can be seen that according to the technical solution of the aforementioned embodiments, for the cross-component prediction derived fusion mode, the chrominance prediction mode that can be used for fusion is flexibly selected through at least one fusion type identification value, which provides a variety of options for the cross-component prediction derived fusion mode, thereby improving the accuracy of chrominance intra-frame prediction, and thus improving the encoding and decoding efficiency.

[0217] In another embodiment of the present application, based on the same inventive concept as the above embodiment, see Figure 14, which shows a schematic diagram of the composition structure of an encoder provided by an embodiment of the present application. As shown in Figure 14, the encoder 130 may include: a first determining part 1301; wherein:

[0218] The first determining part 1301 is configured to determine a value of first syntax identification information; if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, determine a value of second syntax identification information;

[0219] The first determination part 1301 is also configured to determine at least one chroma prediction mode corresponding to the current block and determine at least one fusion type identification value corresponding to the at least one chroma prediction mode if the second syntax identification information indicates that the current block uses the cross-component prediction derived fusion mode; the at least one fusion type identification value is used by the decoder to determine at least one first prediction value of the chroma intra-frame prediction of the current block based on the cross-component prediction derived fusion mode.

[0220] In some embodiments, the first determination part 1301 is further configured to determine at least one encoding cost corresponding to the at least one preset chroma prediction mode; and based on the at least one encoding cost, determine the at least one chroma prediction mode from the at least one preset chroma prediction mode.

[0221] In some embodiments, the at least one preset chroma prediction mode includes at least one of: a cross-component linear model prediction mode, an MMLM mode, a convolutional cross-component model mode, a GLM mode, a DIMD mode, and a DM mode.

[0222] In some embodiments, the first determination part 1301 is further configured to determine, based on the at least one chroma prediction mode, at least one fusion type identification value corresponding to the current block in the preset correspondence between the fusion type identification value and the chroma prediction mode; the preset correspondence includes: at least one preset fusion type identification value corresponding to the at least one preset chroma prediction mode.

[0223] In some embodiments, the first determination part 1301 is further configured to determine the first chroma prediction value corresponding to each preset chroma prediction mode in the at least one preset chroma prediction mode; determine the encoding cost corresponding to each preset chroma prediction mode based on the first chroma prediction value corresponding to each preset chroma prediction mode and the chroma value of the current block, thereby determining the at least one encoding cost.

[0224] In some embodiments, referring to FIG. 14 , the encoder 130 may further include a first prediction part 1303 , wherein:

[0225] The first prediction part 1303 is configured to determine at least one first chroma prediction value corresponding to the at least one chroma prediction mode based on the first chroma prediction value corresponding to each preset chroma prediction mode; use the cross-component prediction derivation mode to perform chroma intra-frame prediction on the current block to determine the second prediction value; and determine the chroma prediction value corresponding to the current block based on the at least one first prediction value and the second prediction value.

[0226] In some embodiments, the first prediction part 1303 is further configured to perform weighted summation of the at least one first prediction value and the second prediction value according to at least two preset weights to determine the weighted sum value; determine a shift factor according to the at least two preset weights, and shift the weighted sum value according to the shift factor to determine the chrominance prediction value.

[0227] In some embodiments, the first prediction part 1303 is further configured to perform chroma intra-frame prediction based on the template area of ​​the current block according to the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode, respectively, if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, and determine the first generation value corresponding to the cross-component prediction derivation mode and the second generation value corresponding to the cross-component prediction derivation fusion mode; determine whether the current block uses the cross-component prediction derivation fusion mode based on the first generation value and the second generation value; if it is determined that the current block uses the cross-component prediction derivation fusion mode, determine at least one fusion type identification value corresponding to the current block.

[0228] In some embodiments, the first prediction part 1303 is further configured to determine at least one fusion type identification value corresponding to the current block based on the chroma frame intra prediction on the template area of ​​the current block when the current block uses cross-component prediction to derive the fusion mode.

[0229] In some embodiments, the first prediction part 1303 is further configured to determine the prediction value of the chroma intra-frame prediction of the current block through the cross-component prediction mode as the chroma prediction value corresponding to the current block if it is determined that the current block does not use the cross-component prediction derivation mode.

[0230] In some embodiments, the first prediction part 1303 is further configured to, if it is determined that the current block does not use the cross-component prediction derivation fusion mode, determine the prediction value of the chroma intra-frame prediction of the current block through the cross-component prediction derivation mode as the chroma prediction value corresponding to the current block.

[0231] In some embodiments, referring to FIG. 14 , the encoder 130 may further include an encoding portion 1302 ; wherein:

[0232] The encoding part 1302 is configured to determine the residual corresponding to the current block based on the chroma prediction value corresponding to the current block and the chroma value of the current block; and generate a code stream based on the residual, the first syntax identification information, the second syntax identification information and the at least one fusion type identification value.

[0233] It should be noted that the description of the above device embodiment is similar to the description of the above method embodiment and has similar beneficial effects as the method embodiment. For technical details not disclosed in the device embodiment of the present invention, please refer to the description of the method embodiment of the present invention for understanding.

[0234] It is understandable that in the embodiments of the present application, a "part" can be a part of a circuit, a part of a processor, a part of a program or software, etc., and of course it can also be a module, or it can be non-modular. Moreover, the various components in this embodiment can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional modules.

[0235] If the integrated unit is implemented as 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, or the portion that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) or a processor to execute all or part of the steps of the method described in this embodiment. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0236] Therefore, an embodiment of the present application provides a storage medium (i.e., a computer-readable storage medium), which is applied to the encoder 130. The computer-readable storage medium stores a computer program, and when the computer program is executed by the first processor, it implements the encoding method described in any one of the aforementioned embodiments.

[0237] Based on the composition of the above-mentioned encoder 130 and the computer-readable storage medium, refer to Figure 15, which shows a specific hardware structure diagram of the encoder 130 provided in an embodiment of the present application. As shown in Figure 15, the encoder 130 may include: a first communication interface 1401, a first memory 1402 and a first processor 1403; each component is coupled together through a first bus system 1404. It can be understood that the first bus system 1404 is used to realize the connection and communication between these components. In addition to the data bus, the first bus system 1404 also includes a power bus, a control bus and a status signal bus. However, for the sake of clarity, various buses are labeled as the first bus system 1404 in Figure 15. Among them:

[0238] The first communication interface 1401 is used to receive and send signals when sending and receiving information with other external network elements;

[0239] A first memory 1402 is used to store computer programs that can be run on the first processor 1403;

[0240] The first processor 1403 is configured to, when running the computer program, execute:

[0241] Determining a value of the first syntax identification information;

[0242] If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, determining a value of the second syntax identification information;

[0243] If the second syntax identification information indicates that the current block uses a cross-component prediction-derived fusion mode, then at least one chroma prediction mode corresponding to the current block is determined, and at least one fusion type identification value corresponding to the at least one chroma prediction mode is determined; the at least one fusion type identification value is used by the decoder to determine at least one first prediction value of the chroma intra-frame prediction of the current block based on the cross-component prediction-derived fusion mode.

[0244] It is understood that the first memory 1402 in the embodiment of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct RAM bus random access memory (DRRAM). The first memory 1402 of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0245] The first processor 1403 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by hardware integrated logic circuits or software instructions in the first processor 1403. The above-mentioned first processor 1403 can 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, or discrete hardware components. The various methods, steps, and logic block diagrams disclosed in the embodiments of this application can be implemented or executed. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the embodiments of this application can be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the first memory 1402 , and the first processor 1403 reads the information in the first memory 1402 and completes the steps of the above method in combination with its hardware.

[0246] It is to be understood that these embodiments described in the present application can be implemented with hardware, software, firmware, middleware, microcode or its combination.For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (Application Specific Integrated Circuits, ASIC), digital signal processor (Digital Signal Processing, DSP), digital signal processing equipment (DSP Device, DSPD), programmable logic device (Programmable Logic Device, PLD), field programmable gate array (Field-Programmable Gate Array, FPGA), general-purpose processor, controller, microcontroller, microprocessor, other electronic units for performing functions described in the present application or its combination.For software implementation, the technology described in the present application can be realized by the module (such as process, function etc.) that performs functions described in the present application. The software code can be stored in a memory and executed by a processor. The memory can be implemented in the processor or outside the processor.

[0247] Optionally, as another embodiment, the first processor 1403 is further configured to execute the encoding method described in any one of the aforementioned embodiments when running the computer program.

[0248] In yet another embodiment of the present application, based on the same inventive concept as the aforementioned embodiment, FIG16 is a schematic diagram showing the structure of a decoder provided by an embodiment of the present application. As shown in FIG16 , the decoder 150 may include: a parsing portion 1501, a second determination portion 1502, and a second prediction portion 1503; wherein:

[0249] The parsing section 1501 is configured to parse a bitstream and determine a value of first syntax identification information; if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, parse the bitstream and determine a value of second syntax identification information; if the second syntax identification information indicates that the current block uses the cross-component prediction derivation fusion mode, parse the bitstream and determine at least one fusion type identification value corresponding to the current block;

[0250] The second determining part 1502 is configured to determine at least one chroma prediction mode corresponding to the current block according to the at least one fusion type identification value.

[0251] The second prediction part 1503 is configured to use the at least one chroma prediction mode to perform chroma intra-frame prediction on the current block to determine at least one first prediction value; use the cross-component prediction derivation mode to perform chroma intra-frame prediction on the current block to determine a second prediction value; and determine the chroma prediction value corresponding to the current block based on the at least one first prediction value and the second prediction value.

[0252] In some embodiments, the second determination part 1502 is further configured to determine at least one chroma prediction mode corresponding to the current block based on the at least one fusion type identification value, in a preset correspondence between the fusion type identification value and the chroma prediction mode; the preset correspondence includes: at least one preset fusion type identification value corresponding to the at least one preset chroma prediction mode.

[0253] In some embodiments, the at least one preset chroma prediction mode includes at least one of: a cross-component linear model prediction mode, an MMLM mode, a convolutional cross-component model mode, a GLM mode, a DIMD mode, and a DM mode.

[0254] In some embodiments, the second prediction part 1503 is further configured to perform chroma intra-frame prediction on the current block through the cross-component prediction mode to determine the chroma prediction value corresponding to the current block if the first syntax identification information indicates that the current block does not use the cross-component prediction derivation mode.

[0255] In some embodiments, the second prediction part 1503 is further configured to perform chroma intra-frame prediction on the current block through the cross-component prediction derivation mode to determine the chroma prediction value corresponding to the current block if the second syntax identification information indicates that the current block does not use the cross-component prediction derivation mode.

[0256] In some embodiments, the second prediction part 1503 is further configured to perform weighted summation of the at least one first prediction value and the second prediction value according to at least two preset weights to determine the weighted sum value; determine a shift factor according to the at least two preset weights, and shift the weighted sum value according to the shift factor to determine the chrominance prediction value.

[0257] In some embodiments, the second determination part 1502 is further configured to, if the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, perform chroma intra-frame prediction based on the template area of ​​the current block according to the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode, respectively, and determine the first generation value corresponding to the cross-component prediction derivation mode and the second generation value corresponding to the cross-component prediction derivation fusion mode; determine whether the current block uses the cross-component prediction derivation fusion mode based on the first generation value and the second generation value; if it is determined that the current block uses the cross-component prediction derivation fusion mode, parse the code stream to determine at least one fusion type identification value corresponding to the current block.

[0258] In some embodiments, the second determination part 1502 is further configured to determine at least one chroma prediction mode corresponding to the current block based on chroma intra-frame prediction on the template area of ​​the current block when the current block uses cross-component prediction to derive a fusion mode.

[0259] It should be noted that the description of the above device embodiment is similar to the description of the above method embodiment and has similar beneficial effects as the method embodiment. For technical details not disclosed in the device embodiment of the present invention, please refer to the description of the method embodiment of the present invention for understanding.

[0260] It is understood that in this embodiment, a "portion" may be a circuit portion, a processor portion, a program portion, or software portion, and may also be a module or non-modular. Furthermore, the various components in this embodiment may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional modules.

[0261] If the integrated unit is implemented as 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, this embodiment provides a storage medium (i.e., a computer-readable storage medium) for use in decoder 150. The computer-readable storage medium stores a computer program that, when executed by a second processor, implements any of the decoding methods described in the aforementioned embodiments.

[0262] Based on the composition of the above-mentioned decoder 150 and the computer-readable storage medium, refer to Figure 17, which shows a specific hardware structure diagram of the decoder 150 provided in an embodiment of the present application. As shown in Figure 17, the decoder 150 may include: a second communication interface 1601, a second memory 1602 and a second processor 1603; each component is coupled together through a second bus system 1604. It can be understood that the second bus system 1604 is used to realize the connection and communication between these components. In addition to the data bus, the second bus system 1604 also includes a power bus, a control bus and a status signal bus. However, for the sake of clarity, various buses are labeled as the second bus system 1604 in Figure 17. Among them:

[0263] The second communication interface 1601 is used to receive and send signals when sending and receiving information with other external network elements;

[0264] The second memory 1602 is used to store computer programs that can be run on the second processor 1603;

[0265] The second processor 1603 is configured to, when running the computer program, execute:

[0266] Parsing the code stream to determine the value of the first syntax identification information;

[0267] If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, parsing the bitstream to determine the value of the second syntax identification information;

[0268] If the second syntax identification information indicates that the current block uses cross-component prediction to derive a fusion mode, parsing the bitstream to determine at least one fusion type identification value corresponding to the current block;

[0269] Determining, according to the at least one fusion type identification value, at least one chroma prediction mode corresponding to the current block;

[0270] Performing chroma intra prediction on the current block using the at least one chroma prediction mode to determine at least one first prediction value;

[0271] Performing chroma intra prediction on the current block using a cross-component prediction derivation mode to determine a second prediction value;

[0272] Based on the at least one first prediction value and the second prediction value, a chrominance prediction value corresponding to the current block is determined.

[0273] Optionally, as another embodiment, the second processor 1603 is further configured to execute the decoding method described in any one of the aforementioned embodiments when running the computer program.

[0274] It can be understood that the hardware functions of the second memory 1602 are similar to those of the first memory 1402, and the hardware functions of the second processor 1603 are similar to those of the first processor 1403; they will not be described in detail here.

[0275] In yet another embodiment of the present application, referring to FIG18 , a schematic diagram of the structure of a coding and decoding system provided by an embodiment of the present application is shown. As shown in FIG18 , the coding and decoding system 170 may include an encoder 1701 and a decoder 1702 .

[0276] In the embodiment of the present application, the encoder 1701 may be the encoder described in any one of the aforementioned embodiments, and the decoder 1702 may be the decoder described in any one of the aforementioned embodiments.

[0277] It should be noted that, in this application, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0278] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0279] The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments.

[0280] The features disclosed in the several product embodiments provided in this application can be arbitrarily combined without conflict to obtain new product embodiments.

[0281] The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0282] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims. Industrial Applicability

[0283] In an embodiment of the present application, when the current block uses the cross-component prediction derivation mode, the decoding end determines that the current block uses the cross-component prediction derivation fusion mode. It can further parse the code stream to obtain at least one fusion type identification value corresponding to the current block sent by the encoding end, determine at least one chroma prediction mode corresponding to the current block based on the at least one fusion type identification value, and then use at least one first prediction value predicted by the at least one chroma prediction mode to fuse with the second prediction value predicted by the cross-component prediction derivation mode to determine the chroma prediction value corresponding to the current block. In other words, the fusion mode of the decoding end can be flexibly selected based on at least one fusion type identification value, providing multiple options for the cross-component prediction derivation fusion mode, thereby improving the prediction accuracy of the chroma fusion mode and thereby improving decoding efficiency.

Claims

1. A decoding method, applied to a decoder, the method comprising: Parsing the code stream to determine the value of the first syntax identification information; If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, parsing the bitstream to determine the value of the second syntax identification information; If the second syntax identification information indicates that the current block uses cross-component prediction to derive a fusion mode, parsing the bitstream to determine at least one fusion type identification value corresponding to the current block; Determining, according to the at least one fusion type identification value, at least one chrominance prediction mode corresponding to the current block; Performing chroma intra prediction on the current block using the at least one chroma prediction mode to determine at least one first prediction value; Performing chroma intra prediction on the current block using a cross-component prediction derivation mode to determine a second prediction value; Based on the at least one first prediction value and the second prediction value, a chrominance prediction value corresponding to the current block is determined.

2. The method according to claim 1, wherein: The determining, according to the at least one fusion type identification value, at least one chroma prediction mode corresponding to the current block comprises: According to the at least one fusion type identification value, in the preset correspondence between the fusion type identification value and the chroma prediction mode, at least one chroma prediction mode corresponding to the current block is determined; the preset correspondence includes: at least one preset fusion type identification value corresponding to at least one preset chroma prediction mode.

3. The method according to claim 2, wherein: The at least one preset chroma prediction mode includes at least one of: a cross-component linear model prediction mode, an MMLM mode, a convolutional cross-component model mode, a GLM mode, a DIMD mode and a DM mode.

4. The method according to any one of claims 1 to 3, wherein: The method further comprises: If the first syntax identification information indicates that the current block does not use the cross-component prediction derivation mode, chroma intra-frame prediction is performed on the current block through the cross-component prediction mode to determine the chroma prediction value corresponding to the current block.

5. The method according to any one of claims 1 to 3, wherein: The method further comprises: If the second syntax identification information indicates that the current block does not use the cross-component prediction derivation fusion mode, chroma intra-frame prediction is performed on the current block through the cross-component prediction derivation mode to determine the chroma prediction value corresponding to the current block.

6. The method according to any one of claims 1 to 3, wherein: The determining, based on the at least one first prediction value and the second prediction value, a chrominance prediction value corresponding to the current block includes: According to at least two preset weights, performing weighted summation on the at least one first prediction value and the second prediction value to determine a weighted sum value; A shift factor is determined according to the at least two preset weights, and the weighted sum value is shifted according to the shift factor to determine the chrominance prediction value.

7. The method according to claim 1, wherein: The method further comprises: If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, then based on the template area of ​​the current block, perform chroma intra prediction according to the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode, respectively, to determine a first generation value corresponding to the cross-component prediction derivation mode and a second generation value corresponding to the cross-component prediction derivation fusion mode; Determining whether the current block uses a cross-component prediction to derive a fusion mode according to the first generation value and the second generation value; If it is determined that the current block uses the cross-component prediction to derive a fusion mode, the bitstream is parsed to determine at least one fusion type identification value corresponding to the current block.

8. The method according to claim 1 or 7, wherein: The method further comprises: In a case where the current block uses cross-component prediction to derive a fusion mode, at least one chroma prediction mode corresponding to the current block is determined according to chroma intra prediction on a template region of the current block.

9. A coding method, applied to an encoder, the method comprising: Determine a value of the first grammar identification information; If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, determining a value of the second syntax identification information; If the second syntax identification information indicates that the current block uses cross-component prediction to derive a fusion mode, determining at least one chroma prediction mode corresponding to the current block, and determining at least one fusion type identification value corresponding to the at least one chroma prediction mode; The at least one merge type identification value is used by a decoder to determine at least one first prediction value of the chroma intra prediction of the current block in a merge mode derived based on cross-component prediction.

10. The method according to claim 9, wherein: The determining at least one chroma prediction mode corresponding to the current block comprises: Determining at least one encoding cost corresponding to the at least one preset chroma prediction mode; Based on the at least one encoding cost, the at least one chroma prediction mode is determined from the at least one preset chroma prediction mode.

11. The method according to claim 9 or 10, wherein: The at least one preset chroma prediction mode includes at least one of: a cross-component linear model prediction mode, an MMLM mode, a convolutional cross-component model mode, a GLM mode, a DIMD mode and a DM mode.

12. The method according to claim 11, wherein: The determining at least one fusion type identification value corresponding to the at least one chroma prediction mode includes: According to the at least one chroma prediction mode, in the preset correspondence between the fusion type identification value and the chroma prediction mode, at least one fusion type identification value corresponding to the current block is determined; the preset correspondence includes: at least one preset fusion type identification value corresponding to at least one preset chroma prediction mode.

13. The method according to claim 10, wherein: The determining at least one encoding cost corresponding to the at least one preset chroma prediction mode includes: Determine a first chroma prediction value corresponding to each preset chroma prediction mode in the at least one preset chroma prediction mode; The encoding cost corresponding to each preset chroma prediction mode is determined according to the first chroma prediction value corresponding to each preset chroma prediction mode and the chroma value of the current block, thereby determining the at least one encoding cost.

14. The method according to claim 13, wherein: The method further comprises: Determining at least one first chroma prediction value corresponding to the at least one chroma prediction mode according to the first chroma prediction value corresponding to each preset chroma prediction mode; Performing chroma intra prediction on the current block using a cross-component prediction derivation mode to determine a second prediction value; Based on the at least one first prediction value and the second prediction value, a chrominance prediction value corresponding to the current block is determined.

15. The method according to claim 14, wherein: The determining, based on the at least one first prediction value and the second prediction value, a chrominance prediction value corresponding to the current block includes: According to at least two preset weights, performing weighted summation on the at least one first prediction value and the second prediction value to determine a weighted sum value; A shift factor is determined according to the at least two preset weights, and the weighted sum value is shifted according to the shift factor to determine the chrominance prediction value.

16. The method according to claim 9, wherein: The method further comprises: If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, then based on the template area of ​​the current block, perform chroma intra prediction according to the cross-component prediction derivation mode and the cross-component prediction derivation fusion mode, respectively, to determine a first generation value corresponding to the cross-component prediction derivation mode and a second generation value corresponding to the cross-component prediction derivation fusion mode; Determining whether the current block uses a cross-component prediction to derive a fusion mode according to the first generation value and the second generation value; If it is determined that the current block uses the cross-component prediction to derive a fusion mode, at least one fusion type identification value corresponding to the current block is determined.

17. The method according to claim 9 or 16, wherein: The method further comprises: In a case where the current block uses cross-component prediction to derive a fusion mode, at least one fusion type identification value corresponding to the current block is determined according to chroma intra prediction on a template region of the current block.

18. The method according to claim 9, wherein: The method further comprises: If it is determined that the current block does not use the cross-component prediction derivation mode, a prediction value of chroma intra prediction performed on the current block using the cross-component prediction mode is determined as the chroma prediction value corresponding to the current block.

19. The method according to claim 9, wherein: The method further comprises: If it is determined that the current block does not use the cross-component prediction derivation fusion mode, the prediction value of the chroma intra-frame prediction of the current block through the cross-component prediction derivation mode is determined as the chroma prediction value corresponding to the current block.

20. The method according to any one of claims 9, 10, 12-16, wherein: The method further comprises: Determining a residual corresponding to the current block according to a chroma prediction value corresponding to the current block and a chroma value of the current block; A code stream is generated based on the residual, the first syntax identification information, the second syntax identification information, and the at least one fusion type identification value.

21. An encoder, comprising: A first determining part, configured to determine a value of the first grammar identification information; If the first syntax identification information indicates that the current block uses the cross-component prediction derivation mode, determining a value of the second syntax identification information; The first determining part is further configured to determine at least one chroma prediction mode corresponding to the current block and determine at least one fusion type identification value corresponding to the at least one chroma prediction mode if the second syntax identification information indicates that the current block uses cross-component prediction to derive a fusion mode; The at least one merge type identification value is used by a decoder to determine at least one first prediction value of the chroma intra prediction of the current block in a merge mode derived based on cross-component prediction.

22. A decoder comprising: A parsing part, configured to parse the code stream to determine a value of the first syntax identification information; If the first syntax identification information indicates that the current block uses the cross-component prediction to derive the mode, the bitstream is parsed to determine the value of the second syntax identification information; if the second syntax identification information indicates that the current block uses the cross-component prediction to derive the fusion mode, the bitstream is parsed to determine at least one fusion type identification value corresponding to the current block; A second determining part is configured to determine at least one chroma prediction mode corresponding to the current block according to the at least one fusion type identification value; The second prediction part is configured to perform chroma intra prediction on the current block using the at least one chroma prediction mode to determine at least one first prediction value; perform chroma intra prediction on the current block using the cross-component prediction derivation mode to determine a second prediction value; Based on the at least one first prediction value and the second prediction value, a chrominance prediction value corresponding to the current block is determined.

23. An encoder, comprising a first memory and a first processor; wherein: The first memory is used to store a computer program that can be run on the first processor; The first processor is configured to execute the method according to any one of claims 9 to 20 when running the computer program.

24. A decoder, comprising a second memory and a second processor; wherein: The second memory is used to store a computer program that can be run on the second processor; The second processor is configured to execute the method according to any one of claims 1 to 8 when running the computer program.

25. A code stream, the code stream being generated by bit encoding according to information to be encoded; wherein, The information to be encoded includes at least one of the following: A value of the first grammar identification information, a value of the second grammar identification information, and at least one fusion type identification value; Among them, the first syntax identification information is used to indicate whether the current block uses a cross-component prediction deriving mode; the second syntax identification information is used to indicate whether the current block uses a cross-component prediction deriving fusion mode; and the at least one fusion type identification value is used to indicate at least one chrominance prediction mode corresponding to the current block.

26. A storage medium, wherein: The storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 1 to 8 is implemented, or the method according to any one of claims 9 to 20 is implemented.