Method for determining predicted direction, decoder, and computer storage medium

Abstract

To provide a method for determining predicted direction, a decoder, and a computer storage medium that can improve decoding accuracy and further improve the transmission quality of image video data.SOLUTION: A method of determining a chroma intra prediction mode of a block to be decoded applied to a decoder includes obtaining a direct mode (DM) mode of a chroma intra prediction mode of a block to be decoded, and determining the DM derivation mode by determining the index number of the prediction direction of the DM derivation mode according to the index number M of the prediction direction of the DM mode and a preset offset N.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present embodiment relates to a technical field of determining a prediction direction in a direct mode (DM) in video decoding, and in particular to a method for determining a prediction direction, a decoder, and a computer storage medium. [Background technology]

[0002] In Versatile Video Coding (VVC), candidate modes for chroma intra prediction modes may include DM mode, Linear Model Prediction (LM), Top Linear Model Prediction (LM_T) mode, Left Linear Model Prediction (LM_L) mode, Direct Current (DC) mode, Stepwise PLANAR mode, Vertical (VER) mode, and Horizontal (HOR) mode.

[0003] Currently, the candidate list of VVC chroma intra prediction modes can be constructed by multiple direct mode signaling (MDMS), where 17 candidate technical proposals need to be compared, the number of comparisons is huge, the dependency on neighboring blocks is high, and the decoding complexity is relatively high. Furthermore, in the structure of the candidate list of chroma intra prediction modes in VVC, when the DM mode is an angle mode, the fixed HOR mode, VER mode, and 66 mode are used as the default angle candidate modes, but the three fixed modes have high sequence dependency, and the matching angle features are usually represented by DM, so they are unlikely to be selected in practical applications. Furthermore, the existing DM modes can only reflect partial texture features of a chroma block, and when a chroma block corresponds to multiple co-located luminance blocks, it is unreasonable to directly use a single DM mode prediction to predict. As can be seen from this, there is a technical problem that prediction is incorrect when decoding with the candidate modes of the existing chroma intra prediction modes. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above circumstances, the present embodiments aim to provide a method for determining a prediction direction, a decoder, and a computer storage medium that can improve the accuracy of chroma intra prediction in a decoder. [Means for solving the problem]

[0005] The technical solution of the present embodiment can be realized as follows.

[0006] According to a first aspect, embodiments of the present invention provide a method, adapted to a decoder, the method comprising: The method includes obtaining a direct mode (DM) of a chroma intra prediction mode of a block to be decoded, and determining the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset offset N, where N is a positive integer greater than or equal to 2, and M is a positive integer.

[0007] In the above technical solution, determining the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset offset N: obtaining a sum value of M and N, obtaining a difference value between M and N, obtaining a minimum value K1 of index numbers of prediction directions included in the DM mode, and a maximum value K2 of index numbers of prediction directions included in the DM mode, and determining the DM derivation mode by determining an index number of the prediction direction of the DM derivation mode according to the sum value, the difference value, K1, and K2.

[0008] In the above technical solution, determining the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to the sum value and the difference value includes: determining, when the sum value is less than or equal to K2 and the difference value is greater than or equal to K1, that index numbers of prediction directions of the DM derivation mode are the sum value and the difference value, respectively; determining, when the difference value is less than or equal to K1, that index numbers of prediction directions of the DM derivation mode are the sum value and a first output value, respectively, where the first output value is a value obtained by inputting M and N into a preset first preset equation; and determining, when the sum value is greater than or equal to K2, that index numbers of prediction directions of the DM derivation mode are the second output value and the difference value, respectively, where the second output value is a value obtained by inputting M and N into a preset second preset equation.

[0009] In the above technical solution, determining the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to the sum value and the difference value includes: determining, when the sum value is less than or equal to K2 and the difference value is greater than or equal to K1, that index numbers of prediction directions in a DM derivation mode are the sum value and the difference value, respectively; determining, when the difference value is less than or equal to K1, that index numbers of prediction directions in a DM derivation mode are the sum value and K1, respectively; and determining, when the sum value is greater than or equal to K2, that index numbers of prediction directions in a DM derivation mode are the difference value and K2, respectively.

[0010] In the above technical solution, when the index number of the prediction direction included in the DM mode is different from the index number of the prediction direction included in the block to be decoded, the DM derivation mode is determined by correspondingly determining the index number of the prediction direction of the DM derivation mode according to the sum value and the difference value; The method includes obtaining a minimum value L1 of the index numbers of the prediction directions included in the block to be decoded and a maximum value L2 of the index numbers of the prediction directions included in the DM mode; obtaining a correspondence relationship between the index numbers of the prediction directions included in the DM mode and the index numbers of the prediction directions included in the block to be decoded; determining an index number from the index numbers of the prediction directions included in the block to be decoded according to the sum value, the difference value, L1, and L2; and determining the DM derivation mode by determining the index number of the prediction direction of the DM mode corresponding to the determined index number as the index number of the prediction direction of the DM derivation mode according to the correspondence relationship.

[0011] In the above technical solution, determining an index number from the index number of the prediction direction included in the block to be decoded according to the sum value, the difference value, L1 and L2, determining, when the sum value is less than or equal to L2 and the difference value is greater than or equal to L1, that the determined index numbers are the sum value and the difference value, respectively; determining, when the difference value is less than or equal to L1, that the determined index numbers are the sum value and a third output value, respectively, where the third output value is a value obtained by inputting M and N into a preset third preset formula; and determining, when the sum value is greater than or equal to L2, that the determined index numbers are a fourth output value and the difference value, respectively, where the fourth output value is a value obtained by inputting M and N into a preset fourth preset formula.

[0012] In the above technical solution, determining an index number from the index number of the prediction direction included in the block to be decoded according to the sum value, the difference value, L1 and L2, determining that the determined index numbers are the sum value and the difference value, respectively, if the sum value is less than or equal to L2 and the difference value is greater than or equal to L1; determining that the determined index numbers are the sum value and L1, respectively, if the difference value is less than or equal to L1; and determining that the determined index numbers are the difference value and L2, respectively, if the sum value is greater than or equal to L2.

[0013] In the above technical solution, after determining the DM derivation mode by determining the index number of the prediction direction of the DM derivation mode according to the index number M of the prediction direction of the DM mode and a preset offset N, the method includes: The method further includes determining that a decoding priority of the DM derivation mode is lower than a priority of the DM mode and lower than a decoding priority of a cross-component linear model prediction (CCLM) mode.

[0014] In the above technical solution, after determining the DM derivation mode by determining the index number of the prediction direction of the DM derivation mode according to the index number M of the prediction direction of the DM mode and a preset offset N, the method includes: The method further includes determining that the decoding priority of the DM derivation mode is lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, higher than the decoding priority of a vertical (VER) mode, and higher than the decoding priority of a horizontal (HOR) mode.

[0015] In the above technical solution, after determining the DM derivation mode by determining the index number of the prediction direction of the DM derivation mode according to the index number M of the prediction direction of the DM mode and a preset offset N, the method includes: The method further includes determining that a decoding priority of the DM derivation mode is lower than a decoding priority of the DM mode, lower than a decoding priority of the CCLM mode, lower than a decoding priority of a direct current (DC) mode, and lower than a decoding priority of a planar (PLANAR) mode.

[0016] In the above technical solution, after determining the DM derivation mode by determining the index number of the prediction direction of the DM derivation mode according to the index number M of the prediction direction of the DM mode and a preset offset N, the method includes: The method further includes determining that the decoding priority of the DM derivation mode is lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, lower than the decoding priority of the DC mode, lower than the decoding priority of the PLANAR mode, higher than the decoding priority of the VER mode, and higher than the decoding priority of the HOR mode.

[0017] According to a second aspect, embodiments of the present invention provide a decoder, the decoder comprising: The present invention comprises: an acquisition module configured to acquire a direct mode (DM) of a chroma intra prediction mode of a block to be decoded; and a first determination module configured to determine the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset offset N, where N is a positive integer greater than or equal to 2, and M is a positive integer.

[0018] In the above technical solution, the first determination module: the first obtaining submodule configured to obtain a minimum value K1 of index numbers of prediction directions included in the DM mode and a maximum value K2 of index numbers of prediction directions included in the DM mode; and a first determination submodule configured to determine the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to the sum value, the difference value, K1, and K2.

[0019] In the above technical solution, the first determination submodule specifically comprises: if the sum value is less than or equal to K2 and the difference value is greater than or equal to K1, determine that index numbers of prediction directions of the DM derivation mode are the sum value and the difference value, respectively; if the difference value is less than or equal to K1, determine that index numbers of prediction directions of the DM derivation mode are the sum value and a first output value, respectively, where the first output value is a value obtained by inputting M and N into a preset first preset formula; if the sum value is greater than or equal to K2, determine that index numbers of prediction directions of the DM derivation mode are the second output value and the difference value, respectively, where the second output value is a value obtained by inputting M and N into a preset second preset formula.

[0020] In the above technical solution, the first determination submodule specifically comprises: If the sum value is smaller than or equal to K2 and the difference value is larger than or equal to K1, the index numbers of the prediction directions of the DM derivation mode are determined to be the sum value and the difference value, respectively; if the difference value is smaller than or equal to K1, the index numbers of the prediction directions of the DM derivation mode are determined to be the sum value and K1, respectively; if the sum value is larger than or equal to K2, the index numbers of the prediction directions of the DM derivation mode are determined to be the difference value and K2, respectively.

[0021] In the above technical solution, if the index number of the prediction direction included in the DM mode is different from the index number of the prediction direction included in the block to be decoded, the first determining sub-module correspondingly: the second acquisition submodule configured to acquire a minimum value L1 of the index numbers of the prediction directions included in the block to be decoded and a maximum value L2 of the index numbers of the prediction directions included in the DM mode; a third acquisition submodule configured to acquire a correspondence relationship between the index numbers of the prediction directions included in the DM mode and the index numbers of the prediction directions included in the block to be decoded; a second determination submodule configured to determine an index number from the index numbers of the prediction directions included in the block to be decoded according to the sum value, the difference value, L1 and L2; and a third determination submodule configured to determine the DM derivation mode by determining the index number of the prediction direction of the DM mode corresponding to the determined index number as the index number of the prediction direction of the DM derivation mode according to the correspondence relationship.

[0022] In the above technical solution, the second determination sub-module specifically comprises: configured to determine, when the sum value is less than or equal to L2 and the difference value is greater than or equal to L1, the determined index numbers are respectively the sum value and the difference value; when the difference value is less than or equal to L1, the determined index numbers are respectively the sum value and a third output value, where the third output value is a value obtained by inputting M and N into a preset third preset formula; and when the sum value is greater than or equal to L2, the determined index numbers are respectively a fourth output value and the difference value, where the fourth output value is a value obtained by inputting M and N into a preset fourth preset formula.

[0023] In the above technical solution, the second determination sub-module specifically comprises: configured to determine that the determined index numbers are the sum value and the difference value, respectively, if the sum value is less than or equal to L2 and the difference value is greater than or equal to L1, determine that the determined index numbers are the sum value and L1, respectively, if the difference value is less than or equal to L1, and determine that the determined index numbers are the difference value and L2, respectively, if the sum value is greater than or equal to L2.

[0024] In the above technical solution, the decoder further comprises: and a second determination module configured to determine, after determining the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset offset N, determine that a decoding priority of the DM derivation mode is lower than a priority of the DM mode and lower than a decoding priority of a cross-component linear model prediction CCLM mode.

[0025] In the above technical solution, the second determination module specifically comprises: The decoding priority of the DM derivation mode is configured to be determined to be lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, higher than the decoding priority of a vertical (VER) mode, and higher than the decoding priority of a horizontal (HOR) mode.

[0026] In the above technical solution, the second determination module specifically comprises: The decoding priority of the DM derivation mode is configured to be determined to be lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, lower than the decoding priority of a direct current (DC) mode, and lower than the decoding priority of a planar (PLANAR) mode.

[0027] In the above technical solution, the second determination module specifically comprises: The decoding priority of the DM derivation mode is configured to be determined to be lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, lower than the decoding priority of the DC mode, lower than the decoding priority of the PLANAR mode, higher than the decoding priority of the VER mode, and higher than the decoding priority of the HOR mode.

[0028] According to a third aspect, embodiments of the present invention provide a decoder, the decoder comprising: The present invention includes a processor and a storage medium having instructions executable by the processor stored thereon, the storage medium performing operations by communicating with the processor via a communication bus, and when the instructions are executed by the processor, performing the method for determining a prediction direction described in the first aspect above.

[0029] According to a fourth aspect, an embodiment of the present application provides a computer storage medium having executable instructions stored thereon, the executable instructions, when executed by one or more processors, causing the processors to perform the method for determining a prediction direction described in the first aspect. Effect of the Invention

[0030] The present embodiment provides a prediction direction determination method, a decoder, and a computer storage medium, the method being applied to a decoder, and the method includes obtaining a DM mode of a chroma intra prediction mode of a block to be decoded, and determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset N, thereby determining a DM derivation mode. That is, in the present embodiment, the DM derivation mode can be determined by determining an index number of a prediction direction of the DM mode among candidate modes of the obtained chroma intra prediction mode and an index number of a prediction direction of the DM derivation mode according to an N value, and the determined DM derivation mode can be used as a candidate mode of the chroma intra prediction mode to perform intra prediction on a chroma frame of the block to be decoded. In this way, by adding the DM derivation mode to the candidate modes of the chroma intra prediction mode and performing intra prediction on the block to be decoded, the accuracy of decoding can be improved, and the transmission quality of image video data can be further improved. [Brief description of the drawings]

[0031] [Figure 1] 1 is an exemplary flowchart of a method for determining a prediction direction according to an embodiment of the present application. [Diagram 2] FIG. 2 is a schematic diagram of a current processing block layout. [Diagram 3] FIG. 2 is a schematic diagram of an arrangement of predicted directions and an arrangement filled with predicted values. [Figure 4] FIG. 2 is a schematic diagram of an arrangement when prediction is performed in VER mode and a schematic diagram of an arrangement when prediction is performed in HOR mode. [Diagram 5] FIG. 2 is a schematic diagram of an arrangement of luminance blocks corresponding to a current processing block; [Figure 6] 13A and 13B are schematic diagrams of the arrangement of chroma blocks adopted in the DM mode and the chroma adjacent block mode of Table 2, respectively. [Figure 7] FIG. 1 is a schematic diagram of the traversal order of intra-prediction directions in MDMS. [Figure 8] 1 is a block diagram showing a configuration of a video encoding system according to an embodiment of the present invention; [Figure 9] 1 is a block diagram showing a configuration of a video decoding system according to an embodiment of the present invention; [Figure 10] 13 is an exemplary flowchart of another method for determining a prediction direction according to an embodiment of the present application; [Figure 11] 13 is an exemplary flowchart of yet another method for determining a prediction direction according to an embodiment of the present application. [Figure 12] FIG. 1 is a first schematic structural diagram of a decoder according to an embodiment of the present invention. [Figure 13] FIG. 2 is a second schematic structural diagram of a decoder according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] In order to more fully understand the features and technical contents of the present embodiment, the present embodiment will be described in detail below with reference to the drawings, which are for illustrative purposes only and are not intended to limit the present embodiment.

[0033] An embodiment of the present application provides a method for determining a prediction direction, which is applied to a decoder. FIG. 1 is an exemplary flowchart of the method for determining a prediction direction according to an embodiment of the present application. As shown in FIG. 1, the method for determining a prediction direction may include the following steps:

[0034] In step S101, the DM mode of the chrominance intra-prediction mode of the block to be decoded is obtained.

[0035] At present, with the rapid development of electronic devices, video encoding and decoding technology is also developing rapidly. Specifically, in video encoding and decoding, the existing reconstructed image in space or time is used to construct a predicted value of the current processing block, and only the difference between the true value and the predicted value is transmitted, thereby achieving the purpose of reducing the amount of transmitted data. This is called predictive coding and decoding.

[0036] FIG. 2 is a schematic diagram of the layout of a current processing block. As shown in FIG. 2, the largest square composed of several small squares in FIG. 2 is the current processing block, the row of circles above the current processing block is the pixel in the first row of the current processing block, and the column of circles to the left of the current processing block is the pixel in the first column of the current processing block. Intra prediction refers to constructing a prediction value of the current processing block using the pixel in the first row and the pixel in the first column of the current processing block. Referring to FIG. 2, the circle in FIG. 2, i.e., the restored neighboring pixels are used to predict each pixel of the current processing block.

[0037] Here, when constructing a prediction value of the current processing block using neighboring pixels, multiple prediction directions are adopted. FIG. 3 is a schematic diagram of an arrangement of prediction directions and a schematic diagram of an arrangement filled with prediction values, and as shown in FIG. 3(a), 67 luma intra prediction modes currently supported by VVC are shown. With the introduction of DM, etc., chroma blocks can also use these intra prediction modes. Here, each prediction mode is represented by an index number, and the value represented by the DM mode may or may not be correlated with the angle. For example, if the DM mode is not correlated with the angle, index number 0 represents the PLANAR mode, index number 1 represents the DC mode, and if the DM mode is the angle mode, index numbers 2 to 66 represent 65 prediction directions.

[0038] It should be noted that the above DC mode and PLANAR mode are two prediction modes with relatively flat structures, where DC mode uses the average value of the reference pixels in the first row and first column to fill the entire luma or chroma block, while PLANAR mode fills the luma or chroma block in a gradual manner.

[0039] FIG. 3(b) is a schematic diagram of an arrangement after being filled with the constructed pixel prediction value, and provides a method for constructing a prediction value for each pixel when the DM mode is an angle mode and the index number of the prediction direction is 66. The pixels numbered 0 to 16 are the data of the first row of the current processing block, and each pixel of the current processing block is filled based on the pixel in the upper right corner, and the filled current processing block is as shown in FIG. 3(b).

[0040] When the DM mode is an angle mode, the index numbers 2 to 66 indicate that the 65 prediction directions also include two special direction modes, for example, index number 18 indicates HOR mode and index number 50 indicates VER mode, which can perform horizontal prediction and vertical prediction, respectively.

[0041] 4 is a schematic diagram of an arrangement when performing prediction in VER mode and a schematic diagram of an arrangement when performing prediction in HOR mode, where as shown in FIG. 4(a), the pixels in the first row are represented by 0, 1, 2, 3, 4, 5, 6, and 7, respectively, and VER mode prediction is performed using the pixels in the first row. As shown in FIG. 4(a), the columns are filled with the pixels in the first row. As shown in FIG. 4(b), the pixels in the first column are represented by 0, 1, 2, 3, 4, 5, 6, and 7, respectively, and HOR mode prediction is performed using the pixels in the first column, and as shown in FIG. 4(b), the rows are filled with the pixels in the first column.

[0042] In practical application, in the case of luminance mode, prediction is sequentially performed according to prediction directions 0 to 66 in FIG. 3(a), and the prediction direction that is most consistent with the current processing block (or has the smallest rate-distortion cost difference value) is selected to construct a prediction value, and the encoding side introduces the difference value and the prediction direction into the bitstream, and the decoding side obtains the index number of the prediction direction by obtaining and analyzing the bitstream, and then calculates a luminance prediction value, and the luminance prediction value is added to the difference value signal analyzed from the bitstream to obtain a reconstructed luminance value.

[0043] In the case of chroma intra prediction, unlike the luma intra prediction mode, only a part of the prediction direction is extracted for the chroma intra prediction direction, so that the complexity can be reduced. For example, the construction method of the candidate list for the chroma intra prediction mode of VVC is as shown in Table 1 below. [Table 1]

[0044] FIG. 5 is a schematic diagram of the arrangement of a luminance block corresponding to a current processing block. As shown in FIG. 5, the grayscale block on the left is a luminance block corresponding to a current chroma block, and the grayscale block on the right is a current chroma block. When performing intra prediction on the current chroma block, the prediction direction of the central block of the luminance block is used, and the central block is a luminance block represented by CR of the grayscale block on the left of FIG. 5.

[0045] As can be seen from Table 1 above, if the prediction direction obtained in DM mode is the same as the last four modes, replace the last four modes with the mode whose prediction direction index number is 66.

[0046] In addition to the above construction method, there is another method, namely, MDMS mode, which is a more complicated construction method of the candidate list of chroma intra prediction mode, and compared with VVC, this method has a 0.2% lower bit rate but is overly complex. The construction method of the technical proposal is as shown in Table 2 below. [Table 2]

[0047] FIG. 6 is a schematic diagram of the arrangement of chroma blocks adopted in the DM mode and chroma adjacent block mode of Table 2, respectively. As shown by the small squares in FIG. 6(a), the DM mode of Table 2 is an intra prediction mode in which the adopted current chroma block corresponds to five positions of the center CR, upper left TL, upper right TR, lower left BL, and lower right BR of the luminance block area. As shown by the small squares in FIG. 6(b), the chroma adjacent block mode of Table 2 is an intra prediction mode in which the adopted chroma block corresponds to five positions of the center CR, upper left TL, upper right TR, lower left BL, and lower right BR of the luminance block area.

[0048] FIG. 7 is a schematic diagram of the traversal order of intra prediction directions in MDMS. As shown in FIG. 7, the order of intra prediction is as follows: 1, center luma block C; 2, top left luma block TL; 3, top right luma block TR; 4, bottom left luma block BL; 5, bottom right luma block BR; 6, left chroma block L; 7, top chroma block; 8, bottom left chroma block LB; 9, top right chroma block AR; 10, top left chroma block AL; 11, PLANAR; 12, DC; 13, add or subtract 1 to the index number of the existing prediction direction (corresponding to +1 derived angular modes); 14, prediction direction index number 50 (corresponding to VER_IDX); 15, prediction direction index number 18 (corresponding to HOR_IDX). 16, prediction direction index number 2. 17, prediction direction index number 34 (corresponding to DIA_IDX).

[0049] As can be seen, although the method of constructing the chroma intra prediction direction in VVC is simple, the fixed HOR, VER and 66 modes adopted are highly sequence-dependent and cannot adapt well to all sequences, and statistics show that the probability of these modes being selected is relatively low.

[0050] MDMS needs to compare 17 candidate technique proposals, which brings about a gain of -0.2%, but the more comparisons, the higher the dependency on neighboring blocks, making it difficult to implement in practice. Currently, there are several ways to reduce the complexity of MDMS (e.g., deleting prediction directions 2, 3, 4, and 5 in FIG. 7, deleting luminance blocks AR, PLANAR, and DC in the upper right corner of FIG. 7, and adding or subtracting 1 to the existing prediction direction index number).

[0051] In order to improve the accuracy of the candidate prediction direction, Fig. 8 is a block diagram of the configuration of a video encoding system according to an embodiment of the present application, and as shown in Fig. 8, the video encoding system 800 includes components such as transform and quantization 801, intra estimation 802, intra prediction 803, motion compensation 804, motion estimation 805, inverse transform and inverse quantization 806, filter control analysis 807, deblocking filtering and sample adaptive offset (SAO) filtering 808, header information coding and context-based adaptive binary arithmetic coding (CABAC) 809, and decoded image cache 810. For an input original video signal, a video coding block can be obtained by dividing a coding tree unit (CTU), and then the video coding block can be transformed by transform and quantization 801 based on residual pixel information obtained by performing intra or inter prediction. Transforming the video coding block by said transform and quantization 801 may include converting residual information from pixel domain to transform domain and quantizing the obtained transform coefficients to further reduce the bit rate. Intra estimation 802 and intra prediction 803 are configured to perform intra prediction on said video coding block, specifically, intra estimation 802 and intra prediction 803 are configured to determine an intra prediction mode to be used to code said video coding block. Motion compensation 804 and motion estimation 805 are configured to provide temporal prediction information by performing inter-predictive coding on the received video coding block relative to one or more blocks in one or more reference frames. Motion estimation performed by motion estimation 805 is a process of generating motion vectors, based on which motion of said video coding block can be estimated, and then motion compensation 804 can perform motion compensation based on the motion vectors determined by motion estimation 805.After determining the intra prediction mode, the intra prediction 803 is further configured to provide the selected intra prediction data to the header information coding and CABAC 809. The motion estimation 805 can also send the motion vector data determined by the calculation to the header information coding and CABAC 809. The inverse transform and inverse quantization 806 is configured to reconstruct the video coding block, i.e., reconstruct a residual block in the pixel domain. Block artifacts of the reconstructed residual block can be removed by the filter control analysis 807 and the deblocking filtering and SAO filtering 808, and then generate a reconstructed video coding block by adding the reconstructed residual block to one predictive block in the frame of the decoded picture cache 810. The header information coding and CABAC 809 is configured to code various coding parameters and quantized transform coefficients, and in a coding algorithm based on CABAC, contextual content can be based on neighboring coding blocks and can be used to code information indicating the determined intra prediction mode and output a bitstream of the video signal. The decoded picture cache 810 is configured to store reconstructed video coding blocks as prediction references. As video pictures are encoded, new reconstructed video coding blocks are continually generated and these reconstructed video coding blocks are stored in the decoded picture cache 810.

[0052] FIG. 9 is a block diagram showing the configuration of a video decoding system according to an embodiment of the present application. As shown in FIG. 9, the video decoding system 900 includes components such as a header information decoding and CABAC decoding 901, an inverse transform and inverse quantization 902, an intra prediction 903, a motion compensation 904, a deblocking filtering and SAO filtering 905, and a decoded image cache 906. After the input video signal is subjected to the encoding process shown in FIG. 8, a bitstream of the video signal is output. The bitstream can be input to the video decoding system 900 and first processed through the header information decoding and CABAC decoding 901 to obtain decoded transform coefficients. The transform coefficients can be processed through the inverse transform and inverse quantization 902 to generate a residual block in the pixel domain. The intra prediction 903 can be configured to generate prediction data of a current video decoding block based on a determined intra prediction mode and data of a previous decoded block from a current frame or image. The motion compensation 904 may determine prediction information of the video decoded block by analyzing the motion vectors and other related syntax elements, and generate a prediction block of the currently decoded video decoded block based on the prediction information. The residual block from the inverse transform and inverse quantization 902 and the corresponding prediction block generated by the intra prediction 903 or the motion compensation 904 are added to form a decoded video block. Block artifacts of the decoded video signal may be removed by the deblocking filtering and SAO filtering 905, thereby improving the video quality. The decoded video block may be stored in a decoded image cache 906, which is configured to store reference images used for subsequent intra prediction or motion compensation, and output a video signal, i.e., a restored original video signal may be obtained.

[0053] The present embodiment is mainly applied to intra prediction 803 shown in Fig. 8 and intra prediction 903 shown in Fig. 9. The present embodiment may be applied to an encoding system or a decoding system, but the present embodiment is not particularly limited thereto.

[0054] Referring to FIG. 1, to obtain the DM derivation mode, firstly, the DM mode is obtained, and thus the index number of the prediction direction of the DM mode can be known.

[0055] In step S102, the DM derivation mode is determined by determining the index number of the prediction direction of the DM derivation mode according to the index number M of the prediction direction of the DM mode and a preset offset N.

[0056] where N is a positive integer greater than or equal to 2, and M is a positive integer.

[0057] Here, the prediction direction represented by the index number included in the DM mode and the prediction direction represented by the index number included in the block to be decoded may be the same or different, which is related to the shape and / or size of the block to be decoded. For example, if the ratio of the width and height of the block to be decoded is the same as the ratio of the width and height of the block shape of the reference region, the index numbers of all prediction directions included in the DM mode are the same as the index numbers of the prediction directions included in the block to be decoded; otherwise, if the ratio of the width and height of the block to be decoded is different from the ratio of the width and height of the block shape of the reference region, in the wide-angle mode, the prediction directions corresponding to the extension mode numbers may be different.

[0058] In practical applications, N is generally 3, 5 or 7, where the present embodiment is not particularly limited thereto.

[0059] To determine the index number of the prediction direction in the DM derivation mode, in one exemplary embodiment, FIG. 10 is an exemplary flowchart of another exemplary prediction direction determination method according to an embodiment of the present application, and as shown in FIG. 10, step S102 may include the following steps:

[0060] In step S1001, the sum of M and N is obtained, and the difference between M and N is obtained.

[0061] In step S1002, the minimum value K1 of the index numbers of the prediction directions included in the DM mode and the maximum value K2 of the index numbers of the prediction directions included in the DM mode are obtained.

[0062] In step S1003, the DM derivation mode is determined by determining the index number of the prediction direction of the DM derivation mode according to the sum value, the difference value, K1 and K2.

[0063] That is, first, the sum of M and N and the difference between M and N are calculated to obtain K1 and K2. Here, there are two cases: in case 1, the index number of the prediction direction included in the DM mode is the same as the index number of the prediction direction included in the block to be decoded; in case 2, the index number of the prediction direction included in the DM mode is different from the index number of the prediction direction included in the block to be decoded.

[0064] When the index number of the prediction direction included in the DM mode and the index number of the prediction direction included in the block to be decoded are the same, in order to determine the index number of the prediction direction of the DM derivation mode, in an exemplary embodiment, step S1003 includes the following steps: If the sum value is less than or equal to K2 and the difference value is greater than or equal to K1, determine that the index numbers of the prediction directions of the DM derivation mode are the sum value and the difference value respectively; if the difference value is less than or equal to K1, determine that the index numbers of the prediction directions of the DM derivation mode are the sum value and the first output value respectively, where the first output value is a value obtained by inputting M and N into a preset first formula; If the sum value is greater than or equal to K2, determining that the index numbers of the prediction directions of the DM derivation mode are respectively a second output value and a difference value, where the second output value is a value obtained by inputting M and N into a preset second preset formula.

[0065] The above first and second preset formulas are obtained according to K1 and K2, and the variables M and N are preset.

[0066] For example, when the DM mode is an angle mode, the minimum value of the index number of the prediction direction included in the DM mode is 2, and the maximum value is 66, and N is added or subtracted from them and mapped to the valid angle range to obtain the DM derivation mode. N is greater than 2, and preferably N is 3, 5 or 7.

[0067] TIFF2025027100000004.tif44170

[0068] TIFF2025027100000005.tif14170

[0069] TIFF2025027100000006.tif15170

[0070] TIFF2025027100000007.tif14170

[0071] Here, the symbol "%" above represents a modulus operation. For example, if the DM mode is 40 and the offset N is set to 5, the index numbers of the prediction directions of the DM derivation modes are 35 and 45. If the DM is 62, the derivation modes are 57 and 3 (62+5=67, 67 is limited to 3 by modulus calculation since it exceeds the range of [2,66] (wide-angle mode excluded)), and can be mapped according to the actual angle range when the wide-angle mode is taken into consideration. Then, the construction method of the chroma intra prediction direction in this embodiment is as shown in Table 3 below. [Table 3]

[0072] If the index number of the prediction direction included in the DM mode and the index number of the prediction direction included in the block to be decoded are the same, in order to determine the index number of the prediction direction of the DM derivation mode, in an exemplary embodiment, step S1003 includes: If the sum value is less than or equal to K2 and the difference value is greater than or equal to K1, determining that the index numbers of the prediction directions of the DM derivation mode are the sum value and the difference value respectively; if the difference value is less than or equal to K1, determining that the index numbers of the prediction directions of the DM derivation mode are the sum value and K1 respectively; If the sum value is greater than or equal to K2, determining that the index numbers of the prediction directions of the DM derivation mode are the difference value and K2, respectively.

[0073] TIFF2025027100000009.tif62169

[0074] TIFF2025027100000010.tif6169

[0075] TIFF2025027100000011.tif6169

[0076] For example, if the DM mode is 40 and the offset N value is set to 5, the DM derivation modes are 35 and 45, and if DM is 62, the derivation modes are 57 and 2 (62+5=67, 67 is outside the range [2,66], so it is limited to 66).

[0077] In one exemplary embodiment, in order to determine the index number of the prediction direction of the DM derivation mode, if the index number of the prediction direction included in the DM mode is different from the index number of the prediction direction included in the block to be decoded, correspondingly, FIG. 11 is an exemplary flowchart of yet another prediction direction determination method according to an embodiment of the present application, and as shown in FIG. 11, step S102 may include the following steps:

[0078] In step S1101, the minimum value L1 of the index numbers of the prediction directions included in the block to be decoded and the maximum value L2 of the index numbers of the prediction directions included in the DM mode are obtained.

[0079] In step S1102, the correspondence between the index number of the prediction direction included in the DM mode and the index number of the prediction direction included in the block to be decoded is obtained.

[0080] In step S1103, an index number is determined from the index numbers of the prediction directions included in the block to be decoded according to the sum value, the difference value, L1 and L2.

[0081] In step S1104, the DM derivation mode is determined by determining the index number of the prediction direction of the DM mode corresponding to the determined index number as the index number of the prediction direction of the DM derivation mode according to the correspondence relationship.

[0082] Specifically, when the block to be decoded is rectangular, the prediction direction represented by the index number included in the block to be decoded is different from the prediction direction represented by the index value included in the DM mode, but has a corresponding relationship. For example, when the block to be decoded is rectangular, the prediction direction included in the block to be decoded corresponds to a direction rotated clockwise or counterclockwise by a certain degree with respect to the prediction direction included in the DM mode, and the index numbers of different prediction directions can correspond to each other, and the index number of the prediction direction of the finally obtained DM derivation mode is within the range of the index number of the prediction direction included in the DM mode.

[0083] In order to determine the index number from the index number of the prediction direction included in the block to be decoded, in one exemplary embodiment, step S1103 includes: determining that if the sum value is less than or equal to L2 and the difference value is greater than or equal to L1, the determined index numbers are the sum value and the difference value, respectively; If the difference value is less than or equal to L1, determining that the determined index numbers are respectively a sum value and a third output value, and the third output value is a value obtained by inputting M and N into a third preset formula; If the sum value is greater than or equal to L2, determining that the determined index numbers are respectively a fourth output value and a difference value, where the fourth output value is a value obtained by inputting M and N into a fourth preset formula.

[0084] The above third and fourth preset formulas are obtained according to L1 and L2, where the variables M and N are preset.

[0085] TIFF2025027100000012.tif54169 [Table 4]

[0086] The process of the DM derivation mode is as follows.

[0087] TIFF2025027100000014.tif16170

[0088] TIFF2025027100000015.tif15170

[0089] TIFF2025027100000016.tif15170

[0090] If the obtained result is 67 to 72, it is mapped to 2 to 66 according to the correspondence in Table 4.

[0091] In order to determine the index number from the index number of the prediction direction included in the block to be decoded, in one exemplary embodiment, step S1103 includes: determining that if the sum value is less than or equal to L2 and the difference value is greater than or equal to L1, the determined index numbers are the sum value and the difference value, respectively; if the difference value is less than or equal to L1, determining that the determined index number is the sum value and L1, respectively; and determining, if the sum value is greater than or equal to L2, that the determined index number is the difference value and L2, respectively.

[0092] For example, the present technology proposes adding a column to the DM derivation mode, and the derivation method in the wide-angle mode is specifically as follows:

[0093] TIFF2025027100000017.tif43170

[0094] TIFF2025027100000018.tif15167

[0095] TIFF2025027100000019.tif6167

[0096] TIFF2025027100000020.tif7167

[0097] If the obtained result is 67 to 72, map it to 2 to 66 according to the correspondence in Table 1.

[0098] In one exemplary embodiment, after step S102, the method further comprises: The method further includes determining that the decoding priority of the DM derivation mode is lower than the decoding priority of the DM mode and lower than the decoding priority of the CCLM mode.

[0099] That is, the DM derivation mode is set after the DM mode and the CCLM mode, and in this way, in the decoding process, the higher the priority, the lower the received bit rate.

[0100] In one exemplary embodiment, after step S102, the method further comprises: The method further includes determining that the decoding priority of the DM derivation mode is lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, higher than the decoding priority of the VER mode, and higher than the decoding priority of the HOR mode.

[0101] When the DM is in angle mode, the chrominance intra prediction direction construction method of this embodiment is as shown in Table 5 below. [Table 5]

[0102] In one exemplary embodiment, after step S102, the method further comprises: The method further includes determining that the decoding priority of the DM derivation mode is lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, lower than the decoding priority of the direct current (DC) mode, and lower than the decoding priority of the PLANAR mode.

[0103] When the DM is in angle mode, the chrominance intra prediction direction construction method of this embodiment is as shown in Table 6 below. [Table 6]

[0104] In one exemplary embodiment, after step S102, the method further comprises: The method further includes determining that the decoding priority of the DM derivation mode is lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, lower than the decoding priority of the DC mode, lower than the decoding priority of the PLANAR mode, higher than the decoding priority of the vertical (VER) mode, and higher than the decoding priority of the horizontal (HOR) mode.

[0105] When the DM is in angle mode, the chrominance intra prediction direction construction method of this embodiment is as shown in Table 7 below. [Table 7]

[0106] As can be seen, according to the embodiment of the present application, the determined DM derivation mode is based on the chroma intra prediction direction construction method of 2.2.1 VVC, and can improve the quality of the candidate prediction direction by extending it according to the DM mode in preference to HOR, VER and 66 fixed modes, and places the DM derivation mode after the CCLM mode and before other angle modes.

[0107] The present embodiment provides a method for determining a prediction direction, which is applied to a decoder, and includes obtaining a DM mode of a chroma intra prediction mode of a block to be decoded, and determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset N, thereby determining a DM derivation mode. That is, in the present embodiment, the DM derivation mode can be determined by determining an index number of a prediction direction of the DM mode among candidate modes of the obtained chroma intra prediction mode and an index number of a prediction direction of the DM derivation mode according to an N value, and the determined DM derivation mode can be used as a candidate mode of the chroma intra prediction mode to perform intra prediction on a chroma frame of the block to be decoded. In this way, by adding the DM derivation mode to the candidate modes of the chroma intra prediction mode and performing intra prediction on the block to be decoded, the accuracy of decoding can be improved, and the transmission quality of image video data can be further improved.

[0108] Based on the same inventive concept as the above embodiment, refer to FIG. 12. FIG. 12 is a first schematic structural diagram of a decoder according to the present embodiment, which includes: The decoding apparatus may include an acquisition module 121 configured to acquire a DM mode of a chroma intra prediction mode of a block to be decoded, and a first determination module 122 configured to determine a DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset offset N, where N is a positive integer greater than or equal to 2 and M is a positive integer.

[0109] In the above technical solution, the first determination module 122: a calculation submodule configured to obtain a sum value of M and N and a difference value of M and N; a first obtaining sub-module configured to obtain a minimum value K1 of an index number of a prediction direction included in the DM mode and a maximum value K2 of an index number of a prediction direction included in the DM mode; a first determining sub-module configured to determine a DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to the sum value, the difference value, K1 and K2.

[0110] In the above technical solution, the first determination submodule specifically comprises: If the sum value is less than or equal to K2 and the difference value is greater than or equal to K1, determine that the index numbers of the prediction direction of the DM derivation mode are the sum value and the difference value respectively; If the difference value is less than or equal to K1, determine that the index numbers of the prediction direction of the DM derivation mode are respectively the sum value and the first output value, where the first output value is a value obtained by inputting M and N into a preset first preset formula; If the sum value is greater than or equal to K2, it is configured to determine that the index numbers of the prediction directions of the DM derivation mode are respectively a second output value and a difference value, where the second output value is a value obtained by inputting M and N into a preset second preset formula.

[0111] In the above technical solution, the first determination submodule specifically comprises: If the sum value is less than or equal to K2 and the difference value is greater than or equal to K1, determine that the index numbers of the prediction direction of the DM derivation mode are the sum value and the difference value respectively; If the difference value is less than or equal to K1, determine that the index numbers of the prediction directions of the DM derivation mode are the sum value and K1 respectively; If the sum value is greater than or equal to K2, the index numbers of the prediction directions of the DM derivation mode are determined to be the difference value and K2, respectively.

[0112] In the above technical solution, if the index number of the prediction direction included in the DM mode is different from the index number of the prediction direction included in the block to be decoded, the first determining sub-module correspondingly: A second obtaining sub-module configured to obtain a minimum value L1 of the index number of the prediction direction included in the block to be decoded and a maximum value L2 of the index number of the prediction direction included in the DM mode; A third obtaining sub-module configured to obtain a correspondence between a prediction direction index number included in the DM mode and a prediction direction index number included in the block to be decoded; A second determining sub-module is configured to determine an index number from the index numbers of the prediction directions included in the block to be decoded according to the sum value, the difference value, L1 and L2; and a third determination submodule configured to determine a DM derivation mode by determining, in accordance with the correspondence relationship, an index number of a prediction direction of the DM mode corresponding to the determined index number as an index number of a prediction direction of the DM derivation mode.

[0113] In the above technical solution, the second determination sub-module specifically comprises: If the sum value is less than or equal to L2 and the difference value is greater than or equal to L1, determine that the determined index numbers are the sum value and the difference value, respectively; If the difference value is less than or equal to L1, determine that the determined index numbers are respectively a sum value and a third output value, where the third output value is a value obtained by inputting M and N into a preset third formula; configured to determine that if the sum value is greater than or equal to L2, the determined index number is respectively a fourth output value and a difference value, where the fourth output value is a value obtained by inputting M and N into a preset fourth formula.

[0114] In the above technical solution, the second determination sub-module specifically comprises: If the sum value is less than or equal to L2 and the difference value is greater than or equal to L1, determine that the determined index numbers are the sum value and the difference value, respectively; If the difference value is less than or equal to L1, determine that the determined index number is the sum value and L1, respectively; If the sum value is greater than or equal to L2, the determined index number is configured to be the difference value and L2, respectively.

[0115] In the above technical solution, the decoder further comprises: and a second determination module configured to determine, after determining the DM derivation mode by determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset offset N, determine that a decoding priority of the DM derivation mode is lower than a priority of the DM mode and lower than a decoding priority of a cross-component linear model prediction CCLM mode.

[0116] In the above technical solution, the second determination module specifically comprises: The decoding priority of the DM derivation mode is configured to be determined to be lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, higher than the decoding priority of the vertical (VER) mode, and higher than the decoding priority of the horizontal (HOR) mode.

[0117] In the above technical solution, the second determination module specifically comprises: The decoding priority of the DM derivation mode is configured to be determined to be lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, lower than the decoding priority of the direct current (DC) mode, and lower than the decoding priority of the PLANAR mode.

[0118] In the above technical solution, the second determination module specifically comprises: The decoding priority of the DM derivation mode is configured to be determined to be lower than the decoding priority of the DM mode, lower than the decoding priority of the CCLM mode, lower than the decoding priority of the DC mode, lower than the decoding priority of the PLANAR mode, higher than the decoding priority of the VER mode, and higher than the decoding priority of the HOR mode.

[0119] As will be appreciated, in this embodiment, a "unit" may be a part of a circuit, a part of a processor, a part of a program or software, etc., and may of course be modular or non-modular.

[0120] In addition, each of the constituent units in this embodiment may be integrated into one processing unit, each unit may be used separately as one unit, or two or more units may be integrated into one unit. The integrated unit may be implemented in the form of hardware or a software functional module.

[0121] If the integrated unit is implemented in the form of a software function module and is not sold or used as an independent product, it can be stored in one computer-readable storage medium. Based on this understanding, the essential part of the technical solution of this embodiment, i.e., the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in one storage medium and includes some instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the method described in this embodiment. The aforementioned storage medium includes various media that can store program codes, such as U disks, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0122] FIG. 13 is a second schematic structural diagram of a decoder according to an embodiment of the present application. As shown in FIG.

[0123] The decoder comprises a processor 131 and a storage medium 132 on which instructions executable by the processor 131 are stored, the storage medium 132 performing operations by communicating with the processor 131 via a communication bus 133, and when the instructions are executed by the processor 131, performing the method for determining a prediction direction according to the above embodiment.

[0124] It should be noted that in practical application, each component of the terminal is coupled via a communication bus 133. It should be understood that the communication bus 133 is used to realize the connection communication between these components. In addition to the data bus, the communication bus 133 further comprises a power bus, a control bus and a status signal bus. However, for the sake of clarity, all the various buses are represented as the communication bus 133 in FIG. 13.

[0125] An embodiment of the present application provides a computer storage medium having executable instructions stored thereon, which, when executed by one or more processors, cause the processors to perform the method for determining a prediction direction described in one or more of the embodiments above.

[0126] It should be understood that the memory in the present embodiment may be volatile or non-volatile memory, or may include both volatile and non-volatile memory. Here, the non-volatile memory may 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 may be a random access memory (RAM) used as an external cache. By way of example and not limitation, many forms of RAM can be used, such as, for example, static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchlink dynamic random access memory (SLDRAM), and direct memory bus random access memory (DR RAM). The memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0127] The processor may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above-mentioned method can be completed through an instruction in the form of a hardware integrated logic circuit or software in the processor. The above-mentioned processor may be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. Each method, step and logic block diagram disclosed in the embodiments of the present application can be realized or executed. The general-purpose processor may be a microprocessor, any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed and completed by a hardware decoding processor, or may be executed and completed by a combination of hardware and software modules in the decoding processor. The software modules may be located in a storage medium familiar to those in the art, such as a random memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is placed in a memory, and the processor reads the information in the memory and completes the steps of the method in combination with the hardware.

[0128] It will be understood that the embodiments described herein can be implemented in hardware, software, firmware, middleware, microcode, or a combination thereof. For a hardware implementation, the processing unit is implemented in one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processing (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field-Programmable Gate Arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units configured to perform the functions described herein, or a combination thereof.

[0129] For a software implementation, the techniques described herein may be implemented through modules (processes, functions, etc.) that perform the functions described herein. The software code may be stored in a memory and executed by a processor. The memory may be implemented within the processor or external to the processor.

[0130] It should be noted that, as used herein, the terms "comprises," "having," or other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a set of elements not only includes those elements, but also includes other elements not expressly listed or that are inherent to those processes, methods, articles, or apparatus. Unless specifically limited, an element qualified with the term "comprises" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0131] The numbers of the above-mentioned embodiments of the present invention do not indicate superiority or inferiority of the embodiments, but are used for convenience of explanation.

[0132] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be realized not only in the form of software and a necessary general-purpose hardware platform, but also in the form of hardware, and in many cases, the former is a more preferred embodiment. Based on this understanding, the essential part of the technical solution of the present application, i.e., the part that contributes to the prior art, can be embodied in the form of a software product, and the computer software product is stored in a storage medium (e.g., ROM / RAM, magnetic disk, optical disk) and includes several instructions for causing a terminal (which may be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0133] Although the present application has been described above with reference to the accompanying drawings, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and are not intended to limit the present application. Those skilled in the art can also make many embodiments under the enlightenment of the present application without departing from the purpose and scope of the claims of the present application, and all of these should be included in the protection scope of the present application. [Industrial Applicability]

[0134] In the present embodiment, the present embodiment provides a prediction direction determination method, a decoder, and a computer storage medium, the method being applied to a decoder, and the method includes obtaining a DM mode of a chroma intra prediction mode of a block to be decoded, and determining an index number of a prediction direction of the DM derivation mode according to an index number M of a prediction direction of the DM mode and a preset N, thereby determining a DM derivation mode. That is, in the present embodiment, the DM derivation mode can be determined by determining an index number of a prediction direction of the DM mode among candidate modes of the obtained chroma intra prediction mode and an index number of a prediction direction of the DM derivation mode according to an N value, and the determined DM derivation mode can be used as a candidate mode of the chroma intra prediction mode to perform intra prediction on a chroma frame of the block to be decoded. In this way, by adding the DM derivation mode to the candidate modes of the chroma intra prediction mode and performing intra prediction on the block to be decoded, the accuracy of decoding can be improved, and the transmission quality of image video data can be further improved.

Claims

1. A method for determining a prediction direction applied to a decoder, comprising the steps of: determining a chrominance intra prediction mode for a block to be decoded; Obtaining a direct mode (DM) of the chrominance intra prediction mode; Determining the DM derivation mode by determining a prediction direction index number corresponding to the DM derivation mode according to an offset N and a prediction direction index number M corresponding to the DM; The DM-derived mode decoding process is performed after a cross-component linear model prediction (CCLM) mode parameter decoding process; Determining the DM derivation mode by determining an index number of a prediction direction corresponding to the DM derivation mode according to an index number M of a prediction direction corresponding to the DM and an offset N, The method for determining a prediction direction includes determining that, when a sum of M and N is greater than a maximum value K2 of the index numbers of the prediction direction included in the DM and a difference between M and N is less than a minimum value K1 of the index numbers of the prediction direction included in the DM, the index numbers of the prediction direction corresponding to the DM derivation mode are K1 and K2, respectively.

2. A method for determining a prediction direction applied to an encoder, comprising the steps of: determining a chrominance intra prediction mode for a block to be coded; Obtaining a direct mode (DM) of the chrominance intra prediction mode; Determining the DM derivation mode by determining a prediction direction index number corresponding to the DM derivation mode according to an offset N and a prediction direction index number M corresponding to the DM; the encoding process of the DM-derived mode is performed after the encoding process of the cross-component linear model prediction (CCLM) mode parameters; Determining the DM derivation mode by determining an index number of a prediction direction corresponding to the DM derivation mode according to an index number M of a prediction direction corresponding to the DM and an offset N, The method for determining a prediction direction includes determining that, when a sum of M and N is greater than a maximum value K2 of the index numbers of the prediction direction included in the DM and a difference between M and N is less than a minimum value K1 of the index numbers of the prediction direction included in the DM, the index numbers of the prediction direction corresponding to the DM derivation mode are K1 and K2, respectively.

3. A decoder comprising: A first acquisition module configured to determine a chroma intra prediction mode of a block to be decoded and acquire a Direct Mode (DM) of the chroma intra prediction mode; a first determination module configured to determine the DM derivation mode by determining an index number of a prediction direction corresponding to the DM derivation mode according to an index number M of a prediction direction corresponding to the DM and an offset N; The DM-derived mode decoding process is performed after a cross-component linear model prediction (CCLM) mode parameter decoding process; The first determination module: the decoder comprising a first determination submodule configured to determine that the index numbers of the prediction directions corresponding to the DM derivation mode are K1 and K2, respectively, when the sum of M and N is greater than the maximum value K2 of the index numbers of the prediction directions included in the DM and the difference between M and N is less than the minimum value K1 of the index numbers of the prediction directions included in the DM.

4. 1. An encoder comprising: a second acquisition module configured to determine a chroma intra prediction mode of a block to be coded and acquire a Direct Mode (DM) of the chroma intra prediction mode; a second determination module configured to determine the DM derivation mode by determining an index number of a prediction direction corresponding to the DM derivation mode according to an index number M of a prediction direction corresponding to the DM and an offset N; the encoding process of the DM-derived mode is performed after the encoding process of the cross-component linear model prediction (CCLM) mode parameters; The second determination module: the encoder further comprising a second determination submodule configured to determine that the prediction direction index numbers corresponding to the DM derivation mode are K1 and K2, respectively, when the sum of M and N is greater than the maximum value K2 of the prediction direction index numbers included in the DM and the difference between M and N is less than the minimum value K1 of the prediction direction index numbers included in the DM.

5. A decoder comprising: A decoder comprising: a processor; and a storage medium having instructions executable by the processor stored thereon, the storage medium performing operations by communicating with the processor via a communication bus, the decoder performing the method for determining a prediction direction according to claim 1 when the instructions are executed by the processor.

6. 1. An encoder comprising: The encoder includes a processor and a storage medium having instructions executable by the processor stored thereon, the storage medium performing operations by communicating with the processor via a communication bus, and the instructions, when executed by the processor, perform the prediction direction determination method of claim 2.

7. 1. A computer-readable storage medium, comprising: The computer-readable storage medium has stored therein instructions executable by a processor, the instructions, when executed by one or more processors, causing the processor to perform the method for determining a prediction direction according to claim 1 or the method for determining a prediction direction according to claim 2. The computer storage medium.

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