Chrominance intraprediction method and apparatus, and computer storage medium

Abstract

A chrominance intra prediction method, a decoder, and a computer storage medium for improving chrominance intra prediction accuracy are provided. [Solution] The chroma intra prediction method includes obtaining a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block (101), and if the DM is a direct current (DC) mode or a planar mode, obtaining a chroma prediction mode set according to an optimized candidate mode (102), wherein the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block.

Description

[Technical Field]

[0001] The present embodiment relates to an intra prediction technique in the field of video coding, and more particularly to a chrominance intra prediction method and apparatus, and a computer storage medium. [Background technology]

[0002] The next-generation video coding standard H.266 or Versatile Video Coding (VVC) supports coding of independent divided blocks of luma and chroma, where one chroma block may correspond to multiple luma blocks. However, the existing Direct Mode (DM) can only reflect partial texture features of the center region of the current chroma block. When one chroma block corresponds to multiple co-located luma blocks, it is unreasonable to directly use a single DM to perform chroma prediction. For example, when the DM is in Direct Current (DC) mode or Planar mode, the current chroma block can be considered flat and smooth. However, when the corresponding multiple luma blocks are not flat, performing chroma intra prediction only through the DM significantly reduces the accuracy of intra prediction, thereby reducing codec efficiency. The chroma prediction mode also has horizontal and vertical directions as default candidates, but in this case, there are few chroma blocks that entirely fill the horizontal and vertical prediction directions, which wastes candidate positions and does not help improve codec efficiency. Summary of the Invention [Problem to be solved by the invention]

[0003] The present embodiment provides a chrominance intra prediction method, a decoder, and a computer storage medium, which can effectively improve the accuracy of intra prediction while simultaneously improving codec efficiency. [Means for solving the problem]

[0004] The technical solution of the present embodiment is realized as follows:

[0005] The present embodiment proposes a chrominance intra-prediction method, which includes: obtaining a direct mode (DM) corresponding to a current chroma block from codestream data corresponding to the current chroma block; If the DM is a direct current (DC) mode or a planar mode, obtaining a chroma prediction mode set according to an optimized candidate mode, wherein the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block.

[0006] An embodiment of the present application proposes a decoder, the decoder comprising: an acquisition unit; The acquisition unit is configured to acquire a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, to acquire a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block.

[0007] An embodiment of the present application proposes a decoder, the decoder comprising a processor, a memory that stores processor-executable instructions, a communication interface, and a bus that connects the processor, the memory, and the communication interface, and the instructions, when executed, cause the processor to realize the above-mentioned chroma intra prediction method.

[0008] An embodiment of the present application proposes a computer-readable storage medium storing a program, which is applied to a decoder, and the program, when executed by a processor, realizes the above-mentioned chrominance intra prediction method. [Effects of the Invention]

[0009]

[0013] The present embodiment provides a chroma intra prediction method, a decoder, and a computer storage medium, in which the decoder obtains a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, obtains a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block. As can be seen, in the present embodiment, after obtaining the DM from the code stream data of the current chroma block, if the DM is a DC mode or a planar mode, the decoder can construct a chroma prediction mode set using the optimized candidate mode, and then reconstruct the current chroma block according to the chroma prediction mode set, thereby solving the problem of low chroma intra prediction accuracy when the DM is a DC mode or a planar mode, and further improving codec efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating intra prediction. [Figure 2] 67 is a diagram showing intra prediction modes. [Figure 3] 1 is a diagram illustrating an intra prediction method. [Figure 4] 1 is a diagram illustrating vertical prediction. [Figure 5] 10 is a diagram illustrating horizontal prediction. [Figure 6] 10 is a diagram showing a chroma intra candidate mode set. [Figure 7] 1 is a diagram showing chroma blocks and luma blocks. [Figure 8] 2 is a diagram showing chroma blocks and luminance blocks. [Figure 9] 1 is an exemplary flowchart of video encoding. [Figure 10] 1 is an exemplary flowchart of video decoding. [Figure 11] 1 is a flowchart illustrating an exemplary implementation of a chrominance intra-prediction method according to an embodiment of the present disclosure. [Figure 12] FIG. 1 is a diagram illustrating establishing an optimization candidate mode. [Figure 13] FIG. 2 is a diagram illustrating establishing an optimization candidate mode. [Figure 14] FIG. 3 shows establishing an optimization candidate mode. [Figure 15] FIG. 4 is a diagram illustrating establishing an optimization candidate mode. [Figure 16] FIG. 5 is a diagram illustrating establishing an optimization candidate mode. [Figure 17] 1 is an exemplary structural diagram of a decoder configuration according to an embodiment of the present invention; [Figure 18] 2 is an exemplary structural diagram of a decoder configuration according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to describe related applications and are not intended to limit the applications. Furthermore, for the sake of simplicity, the drawings only show parts related to the related applications.

[0012] In video coding, a predicted value of a current processing block is constructed using an existing re-established image in space or time, and only the difference between the actual value and the predicted value is transmitted, thereby achieving the purpose of reducing the amount of data transmitted. Here, intra-prediction utilizes the spatial correlation within a picture or within a picture region. The intra-prediction of a current processing block can be performed depending on the pixels of the processed adjacent processing blocks. For example, the upper and left columns of the current processing block are used to construct a predicted value of the current processing block. Figure 1 is a schematic diagram of intra-prediction, and as shown in Figure 1, pixels of adjacent processing blocks are used to predict each pixel of the current processing block.

[0013] When performing intra prediction, the selection of the prediction direction is also important. Specifically, when constructing a predicted value of a current processing block using pixels of neighboring coding blocks, multiple prediction directions can be adopted. For example, FIG. 2 is a diagram showing 67 intra prediction modes. As shown in FIG. 2, the 67 intra prediction modes specifically include 65 prediction directions with prediction direction index numbers 2 to 66, and further include a planar mode with index number 0 and a DC mode with index number 1.

[0014] In an embodiment of the present application, based on the above-mentioned FIG. 2, FIG. 3 is a diagram illustrating an intra prediction method. As shown in FIG. 3, when constructing each pixel predicted value with a prediction direction index number of 66, pixels with reference numbers 0 to 16 are the upper data of the current processing block. Each pixel of the current processing block is filled according to the pixel of the upper right diagonal.

[0015] In the embodiment of the present application, the Planar mode is mainly used in areas where the image texture is relatively smooth and the process is relatively slow, and its prediction method is to use the reconstructed pixel value of the neighboring processing block corresponding to the current processing block as the reference pixel value, and then perform linear interpolation and averaging calculations.

[0016] Compared with the planar mode, the DC mode is mainly used for flat images, smooth textures, and areas without excessive gradients, and the specific prediction method is to predict according to the reference pixel of the last decoded line at the top of the current processing block and the reference pixel of the decoded rightmost column on the left side of the current processing block. As can be seen, in intra prediction, the planar mode and the DC mode are both methods for constructing a relatively flat prediction block, with the DC mode using the average value of the reference pixel in the top left column to fill all chroma blocks, and the planar mode adopting a looser method to fill chroma blocks.

[0017] In the above FIG. 2, there are two special direction modes, namely, VER mode (ie, vertical prediction) with prediction direction index number 50, and HOR mode (ie, horizontal prediction) with prediction direction index number 18.

[0018] FIG. 4 is a diagram showing vertical prediction, and FIG. 5 is a diagram showing horizontal prediction. As shown in FIGS. 4 and 5, when the prediction direction is vertical prediction, vertical prediction can be performed according to pixel values ​​perpendicular to the corresponding pixel in the upper row, and when the prediction direction is horizontal prediction, horizontal prediction can be performed according to pixel values ​​horizontal to the corresponding pixel in the left column.

[0019] When performing luma intra prediction, prediction is performed according to modes 0 to 66 in Figure 2 above, and then the prediction direction with the smallest difference from the current processing block, i.e., the most matching prediction direction, is selected to construct the predicted value. The encoding end writes the difference and prediction direction into the codestream. The decoding end obtains and analyzes the codestream to obtain the prediction direction index number, and then calculates the luma prediction value, which is added to the difference signal analyzed by the codestream to obtain the luma reestablishment value.

[0020] However, chrominance intraprediction and luma intraprediction modes are different, and to reduce the complexity of the codec, only a part of the prediction directions is extracted and processed when performing chrominance intraprediction. For example, in VVC, the chrominance intra candidate mode set may include one or more chrominance intraprediction modes, such as Linear Model Prediction (LM), left linear model prediction (LM_T) mode, right linear model prediction (LM_L) mode, DC mode, Planar mode, vertical (VER) mode, and horizontal (HOR) mode.

[0021] FIG. 6 is a diagram showing a chroma intra candidate mode set. As shown in FIG. 6, the chroma intra candidate mode set may include different modes. Prior art techniques can perform chroma intra prediction by selecting one of the different modes. For example, DM may represent the prediction mode of a corresponding luminance center block. Cross-component Linear Model Prediction (CCLM) may represent constructing a prediction signal using a scheme of (a*luminance value+b), where a and b are both natural numbers. When DM is any one of DC mode, Planar mode, VER mode, or HOR mode, the mode may be replaced with an angle mode whose prediction direction index number is 66.

[0022] Furthermore, if a codec framework supports independent division of luminance and chrominance, i.e., the divisions may not be identical, so that one chroma block may correspond to multiple luminance blocks. FIG. 7 is a diagram 1 showing a chroma block and a luminance block, and FIG. 8 is a diagram 2 showing a chroma block and a luminance block. As shown in FIGS. 7 and 8, the luminance block in FIG. 8 corresponding to the chroma block in FIG. 7 includes parts of five independent encodings (shown in different gray levels). Since the CR in DM can only reflect partial texture characteristics of a chroma block, it is unreasonable to directly use a single DM prediction when a chroma block corresponds to multiple co-located luminance blocks. For example, in FIG. 7, if the prediction mode of the luminance-center block is selected as DC mode or Planar mode, the current block should be considered as flat, but the current luminance block in FIG. 7 may not be flat. The chroma prediction mode also has horizontal and vertical directions as default candidates, but in this case, there are few chroma blocks that entirely fill the horizontal and vertical prediction directions, which wastes candidate positions and does not help improve codec efficiency.

[0023] In an embodiment of the present application, the above-described chrominance intra prediction method can be applied to an intra prediction unit within a video coding hybrid framework. In addition to being applicable to VVC, it can also be applied to any other video coding hybrid framework. This application will exemplarily describe the VVC, but is not limited to it. Specifically, the above-described chrominance intra prediction method can operate simultaneously at the encoding end and the decoding end. For example, FIG. 9 is an exemplary flowchart of video coding. As shown in FIG. 9, video coding may include multiple specific steps, such as intra estimation, intra prediction, and motion compensation, where the chrominance intra prediction method according to the present application can be applied to an intra prediction unit. FIG. 10 is an exemplary flowchart of video decoding. As shown in FIG. 10, video decoding may include multiple specific steps, such as filtering, intra prediction, and motion compensation, where the chrominance intra prediction method according to the present application can be applied to an intra prediction unit.

[0024] Hereinafter, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application.

[0025] In one embodiment, the present embodiment provides a chrominance intra prediction method, and FIG. 11 is an exemplary implementation flowchart of the chrominance intra prediction method according to the present embodiment. As shown in FIG. 11 , in the present embodiment, the method in which the decoder performs chrominance intra prediction may include the following steps:

[0026] In step 101, the DM corresponding to the current chroma block is obtained from the codestream data corresponding to the current chroma block.

[0027] In an embodiment of the present application, the decoder can obtain the DM corresponding to the current chroma block from the codestream data corresponding to the current chroma block.

[0028] It should be noted that in the present embodiment, the decoder may first receive a video bitstream, and then obtain the codestream data corresponding to the current coding block from the received video bitstream.

[0029] In the implementation of the present application, after obtaining the codestream data corresponding to the current coding block, the decoder can also obtain the residual data corresponding to the current chroma block from the codestream data.

[0030] It should be noted that in an embodiment of the present application, when an encoder selects a luma intra prediction mode, it can predict according to multiple modes, for example, modes 0 to 66 in FIG. 2 above, and then select the most matching prediction direction to construct a predicted value. However, when an encoder selects a chroma intra prediction mode, it does not predict all modes 0 to 66, but extracts and predicts and selects only a portion of the prediction directions. Therefore, after obtaining the codestream data, the decoder selects one chroma intra candidate set corresponding to the current chroma block from the codestream data, i.e., a chroma prediction direction corresponding to the chroma block. Measurement mode sets can be further constructed.

[0031] In an embodiment of the present application, the chroma prediction mode set may include at least one chroma intra prediction mode, for example, the chroma prediction mode set may include modes such as DM, LM, LM_T, LM_L, DC, Planar, and other directional prediction modes.

[0032] In the embodiment of the present application, the current chroma block may be a square chroma block or a rectangular chroma block, and the embodiment of the present application is not specifically limited.

[0033] In step 102, if the DM is DC mode or Planar mode, obtain a chroma prediction mode set according to the optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block.

[0034] In an embodiment of the present application, a decoder may obtain a DM corresponding to a current chroma block from codestream data corresponding to the current chroma block. If the DM is in DC mode or planar mode, the decoder may obtain a chroma prediction mode set according to an optimized candidate mode. Here, the chroma prediction mode set may be used to perform intra-chroma prediction on the current chroma block.

[0035] It should be noted that in the present embodiment, a chroma prediction mode set is used for chroma prediction, and specifically, the decoder can perform chroma prediction on a current chroma block via the chroma prediction mode set, thereby restoring the chroma corresponding to the current chroma block.

[0036] In an embodiment of the present application, after a decoder obtains a DM corresponding to a current chroma block from the codestream data corresponding to the current chroma block, the decoder can determine whether the DM is in DC mode or planar mode.

[0037] It should be noted that in an embodiment of the present application, if the decoder determines that the DM is DC mode or Planar mode, the encoder can add modes according to the optimized candidate modes, thereby obtaining a chroma prediction mode set.

[0038] In an embodiment of the present application, after the decoder determines the DM corresponding to the current chroma block from the codestream data, it can first read and analyze the DM, thereby determining whether the DM is in DC mode or Planar mode.

[0039] In the implementation of the present application, since both planar mode and DC mode are methods for constructing flat prediction blocks, it should be noted that when a luminance center block is selected as DC mode or planar mode in DM, the luminance block can be considered flat. However, this is not the case in practice. For example, VVC supports coding independent divided blocks of luminance and chrominance, and one chrominance block may correspond to multiple luminance blocks. Therefore, the DM can only reflect partial texture features of the center region, that is, the luminance block may not be flat. In other words, when the DM is planar mode or DC mode, it is unreasonable to directly use a single DM for prediction, which reduces accuracy. The chrominance prediction mode also has horizontal and vertical directions as default candidates. However, in this case, there are few chroma blocks that entirely fill the horizontal and vertical prediction directions, which wastes candidate positions and does not contribute to improving codec efficiency.

[0040] In the implementation of the present application, Table 1 is the initial state of the intra-prediction direction design table. As shown in Table 1, if the DM is in DC mode or planar mode, the initial state of the prediction direction is DC mode or planar mode. Table 2 is the subsequent state of the intra-prediction direction design table. As shown in Table 2, if the corresponding luminance center block is in planar mode or DC mode, it indicates that if all luminance blocks adopt one intra-prediction direction, it indicates that the current block is likely to be flat, and another flat mode is entered to ensure the efficiency of flat blocks. Here, DM and CCLM are important coding tools, so they need to be prioritized. [Table 1] [Table 2]

[0041] Currently, only flat information in DC mode or planar mode can be obtained through the luma block. However, in reality, the corresponding chroma block may cover multiple luma block regions, which contain directional texture information, and the directions of these texture information are distributed with different probabilities.

[0042] On the other hand, in the prior art, when the DM is any one of the DC mode, the Planar mode, the VER mode, and the HOR mode, the mode can be replaced with a directional mode whose prediction direction index number is 66.

[0043] However, in practical applications, the VER and HOR modes with prediction direction index numbers 18 and 50 have a large proportion, but the probability of texture across all chroma blocks is very small; in comparison, the diagonal angle modes and their nearby direction modes with prediction direction index numbers 34, 66, and 2 can correctly predict chroma blocks with a higher probability.

[0044] Therefore, since DM cannot reflect only partial texture features of a chroma block, when a chroma block corresponds to multiple co-located luminance blocks, it is unreasonable to directly use a single DM prediction and construct a chroma prediction mode set by supplementing horizontal, vertical, and diagonal modes corresponding to the prediction direction index number 66. Therefore, the decoder needs to perform optimization construction on the chroma prediction mode set according to the optimization candidate modes. At the same time, in practical applications, the diagonal angle modes with prediction direction index numbers 34, 66, and 2 and their nearby direction modes can correctly predict chroma blocks with a higher probability, so these prediction direction modes can be used to replace the original horizontal and vertical prediction direction modes, etc., and further supplement the DM.

[0045] In the embodiment of the present application, when the DM is the DC mode or the Planar mode, the decoder can further obtain a chroma prediction mode set for chroma prediction according to the optimized candidate mode.

[0046] It should be noted that in the present embodiment, the decoder may pre-configure at least one mode as a candidate mode, i.e. the decoder is pre-configured with an optimized candidate mode.

[0047] In an embodiment of the present application, the diagonal angle modes with prediction direction index numbers 34, 66, and 2 are used to predict small blocks in the luminance domain corresponding to the current chroma, and therefore the optimized candidate modes may store modes with prediction direction index numbers 34, 66, and 2. For example, if the current chroma block is a square chroma block, that is, if the diagonal angle modes of the current chroma block are modes with prediction direction index numbers 34, 66, and 2, when the decoder obtains a chroma prediction mode set according to the optimized candidate modes, it may first add the mode with prediction direction index number 34 to the chroma prediction mode set, and then add one of the modes with another diagonal angle direction, prediction direction index numbers 66 and 2, to the chroma prediction mode set.

[0048] In an embodiment of the present application, since the modes with prediction direction index numbers 66 and 2 belong to two directions of one gradient, the decoder can adjust the mode with prediction direction index number 2 by one angle in a clockwise direction to become the optimized candidate mode, for example, to adjust it to a mode with prediction direction index number 6. At the same time, the decoder can also adjust the mode with prediction direction index number 66 by one angle in a counterclockwise direction to become the optimized candidate mode, for example, to adjust it to a mode with prediction direction index number 61. Furthermore, the decoder can also simultaneously adjust the mode with prediction direction index number 66 and the mode with prediction direction index number 2 by one angle to become the optimized candidate mode.

[0049] In an embodiment of the present application, in addition to using more diagonal angle modes for prediction, other derived angles near the diagonal angle modes are also used for prediction, so the optimized candidate modes may include modes with prediction direction index numbers of 32, 64, and 4. For example, when a decoder obtains a chroma prediction mode set according to the optimized candidate modes, it may first add the mode with prediction direction index number 34 to the chroma prediction mode set, and then add one of the modes with prediction direction index numbers 66 and 2 to the chroma prediction mode set.

[0050] In summary, in an embodiment of the present application, when a decoder establishes an optimized candidate mode, it can determine at least one diagonal angle mode as the optimized candidate mode, can determine a derivative angle mode of the at least one diagonal angle mode as the optimized candidate mode, and can further determine at least one diagonal angle mode and a derivative angle mode of the at least one diagonal angle mode as the optimized candidate mode. Here, the decoder can first determine a derived angle. Specifically, the decoder can first determine an index number M corresponding to a DM, where M is an integer greater than 0, then obtain a transformation parameter N, and finally, can further determine an index number corresponding to a derived angle mode according to M and N to obtain a derived angle mode, where N is an integer greater than 0.

[0051] In an embodiment of the present application, when the decoder determines an index number corresponding to a derived angular mode according to M and N, it may perform an addition operation on M and N, and a subtraction operation on M and N to finally obtain an index number corresponding to the derived angular mode. Here, the value of N may be 3, 5, or 7, but is not limited to these values. For example, if the index number M corresponding to DM is 1 (i.e., the DM is in DC mode), the decoder may determine the angular direction obtained by 1+5 or 1-5 as the index number corresponding to the derived angular mode. Since prediction modes are usually not represented by negative numbers, a specific mapping method may be used to map the calculated value to the valid display range. For example, a specific calculation formula may be (M+62-N)%64+2, which obtains 60.

[0052] In an embodiment of the present application, for the wide-angle mode of a non-square block, further, according to its valid prediction direction range, one direction of the modes with prediction direction index numbers 66 and 2 can be selected as a candidate, and the angle corresponding to another number can be adjusted to become a candidate.

[0053] In an embodiment of the present application, after the decoder obtains the chroma prediction mode set according to the optimized candidate mode, i.e., after step 102, a method for the decoder to perform chroma intra prediction may include the following steps.

[0054] In step 103, a decoding process is performed according to the chroma prediction mode set to perform chroma reconstruction on the current chroma block.

[0055] In an embodiment of the present application, after the decoder obtains a chroma prediction mode set according to the optimized candidate mode, it can perform a decoding process according to the chroma prediction mode set to perform chroma reconstruction on the current chroma block.

[0056] In an embodiment of the present application, after the decoder obtains a chroma prediction mode set, it can further perform a decoding process on the current chroma block via the chroma prediction mode set, thereby restoring the current chroma block.

[0057] It should be noted that in the embodiment of the present application, when the decoder obtains code stream data corresponding to the current coding block from the received video bitstream and obtains the DM from the code stream data, the decoder can also obtain residual data corresponding to the current chroma block from the code stream data.

[0058] In an embodiment of the present application, after the decoder obtains a chroma prediction mode set according to the optimized candidate mode, it can simultaneously obtain residual data corresponding to a current chroma block from the codestream data, and then perform chroma intra-prediction decoding on the residual data based on the chroma prediction mode set, thereby restoring the current chroma block.

[0059] In the chroma intra prediction method according to the embodiment of the present application, the decoder obtains a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, obtains a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block. As can be seen, in the embodiment of the present application, after obtaining the DM from the code stream data of the current chroma block, if the DM is a DC mode or a planar mode, constructs a chroma prediction mode set using the optimized candidate mode, and then The current chroma block can be reconstructed according to the prediction mode set, thereby solving the problem of low chroma intra prediction accuracy that exists when the DM is in DC mode or Planar mode, and further improving codec efficiency.

[0060] According to the above embodiment, in another embodiment of the present application, after a decoder obtains a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, if the DM of the DM is DC mode or Planar mode, it is deemed that the decoder needs to obtain a chroma prediction mode set according to an optimized candidate mode, thereby improving the decoding accuracy.

[0061] In the implementation of the present application, since both planar mode and DC mode are methods for constructing flat prediction blocks, it should be noted that when a luminance center block is selected as DC mode or planar mode in DM, the luminance block can be considered flat. However, this is not the case in practice. VVC supports coding independent divided blocks of luminance and chrominance, and one chrominance block may correspond to multiple luminance blocks. Therefore, the DM can only reflect partial texture features of the center region, that is, the luminance block may not be flat. In other words, when the DM is planar mode or DC mode, it is unreasonable to directly use a single DM for prediction, which reduces accuracy. Chroma prediction modes also have horizontal and vertical directions as default candidates. However, in this case, there are few chroma blocks that completely fill the horizontal and vertical prediction directions, which wastes candidate positions and does not contribute to improving codec efficiency. Therefore, it is necessary to obtain a chroma prediction mode set according to the optimized candidate mode. Specifically, before obtaining the chroma prediction mode set according to the optimized candidate mode, the decoder further needs to obtain the linear mode (LM) corresponding to the current chroma block from the codestream data.

[0062] In the implementation of the present application, the method for the decoder to obtain a chroma prediction mode set according to the optimized candidate mode may specifically include the following steps.

[0063] In step 201, DM and LM are filled into a chroma prediction mode set.

[0064] In step 202, the chroma prediction mode set is filled according to the optimized candidate modes.

[0065] In the present embodiment, the decoder can first add DM and LM to the chroma prediction mode set, respectively, thereby first determining two modes in the chroma prediction mode set, and then continue to fill the chroma prediction mode set according to the optimized candidate modes, and finally obtain a chroma prediction mode set.

[0066] In an embodiment of the present application, when the decoder adds DM and LM to the chroma prediction mode set, it specifically adds the prediction direction index number of the mode corresponding to DM and the prediction direction index number of the mode corresponding to LM to the prediction mode set. For example, if DM is DC mode and the prediction direction index number of the mode corresponding to LM is 15, the decoder first adds prediction direction index numbers 1 and 15 to the chroma prediction mode set, respectively, and then fills the chroma prediction mode set according to the optimized candidate mode. Specifically, because DM is DC mode, the decoder supplements the prediction direction index number 0 of Planar mode to the chroma prediction mode set in the process of filling the chroma prediction mode set according to the optimized candidate mode.

[0067] It should be noted that in the embodiment of the present application, when the decoder fills the chroma prediction mode set according to the optimized candidate mode, it may specifically include the following steps:

[0068] In step 202a, if the DM is in DC mode, it fills the chroma prediction mode set with the Planar mode and the optimized candidate modes.

[0069] In an embodiment of the present application, if the DM corresponding to the current chroma block is DC mode, the decoder does not need to modify and replace the Planar mode, and therefore fills the chroma prediction mode set with the Planar mode and the optimized candidate modes, and does not need to be in a specific order if the number of allocated bits is the same.

[0070] It should be noted that in an embodiment of the present application, when the decoder adds the planar mode and the optimized candidate modes to the chroma prediction mode set, it specifically adds the prediction direction index numbers corresponding to the planar mode and the prediction direction index numbers corresponding to the other optimized candidate modes to the prediction mode set. For example, if the other optimized candidate modes correspond to prediction direction index numbers 32 and 61, the decoder may add prediction direction index numbers 0, 132, and 61 to the chroma prediction mode set, respectively.

[0071] In step 202b, if the DM is in the planar mode, the DC mode and the optimized candidate modes are filled into the chroma prediction mode set.

[0072] In an embodiment of the present application, if the DM corresponding to the current chroma block is a Planar mode, the decoder does not need to modify or replace the DC mode, and therefore fills the DC mode and the optimized candidate modes into the chroma prediction mode set, and does not need to be in any particular order if the number of allocated bits is the same.

[0073] It should be noted that in an embodiment of the present application, when the decoder adds the DC mode and the optimized candidate modes to the chroma prediction mode set, it specifically adds the prediction direction index number corresponding to the DC mode and the prediction direction index numbers corresponding to the other optimized candidate modes to the prediction mode set. For example, if the other optimized candidate modes correspond to prediction direction index numbers of 2 and 60, the decoder may add prediction direction index numbers 1, 2, and 60 to the chroma prediction mode set, respectively.

[0074] In the embodiment of the present application, the method for the decoder to add the optimized candidate mode to the chroma prediction mode set may further include the following steps.

[0075] In step 301, a priority is determined for at least one of the optimization candidate modes.

[0076] In an embodiment of the present application, the decoder may first determine a priority of at least one of the optimization candidate modes.

[0077] It should be noted that in the embodiment of the present application, the optimization candidate mode may be at least one mode, and specifically, the prediction direction index numbers of the at least one mode are all different.

[0078] It should be noted that in the present embodiment, the decoder may determine the priority according to the probability that at least one mode will actually be used.

[0079] In step 302, the optimization candidate modes are added to the chroma prediction mode set in descending order of priority.

[0080] In an embodiment of the present application, after the decoder determines the priority of at least one of the optimized candidate modes, it can further add the optimized candidate modes to the chroma prediction mode set in order of decreasing priority.

[0081] In an embodiment of the present application, in the process of the decoder adding an optimized candidate mode to a chroma prediction mode set, the decoder can first add the optimized candidate mode with the highest priority, and then select the next optimized candidate mode in descending order of priority to construct the chroma prediction mode set.

[0082] It should be noted that in the present embodiment, when the decoder adds an optimized candidate mode to the chroma prediction mode set, it specifically adds a prediction direction index number corresponding to the optimized candidate mode to the prediction mode set.

[0083] That is, if the decoder can construct a chroma prediction mode set according to the preset optimized candidate modes, the accuracy of prediction can be improved.

[0084] In the chroma intra prediction method according to the present embodiment, the decoder obtains a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, obtains a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block. As can be seen, in the present embodiment, after obtaining the DM from the code stream data of the current chroma block, if the DM is a DC mode or a planar mode, the decoder can construct a chroma prediction mode set using the optimized candidate mode and then reconstruct the current chroma block according to the chroma prediction mode set, thereby solving the problem of low chroma intra prediction accuracy when the DM is a DC mode or a planar mode and further improving codec efficiency.

[0085] In an embodiment of the present application, the current chroma block includes a square chroma block and a non-square chroma block, whereby, when the decoder establishes the optimized candidate modes, it can determine at least one diagonal angle mode as the optimized candidate mode, can also determine a derivative angle mode of the at least one diagonal angle mode as the optimized candidate mode, and can further determine the at least one diagonal angle mode and a derivative angle mode of the at least one diagonal angle mode as the optimized candidate mode.

[0086] In an embodiment of the present application, the decoder may determine at least one diagonal angle mode as an optimized candidate mode. Specifically, if a current chroma block is a square chroma block, i.e., if the diagonal angle mode of the current chroma block is a mode with prediction direction index numbers 34, 66, and 2, the diagonal angle modes with prediction direction index numbers 34, 66, and 2 are used for prediction. Figure 12 is a diagram 1 illustrating establishing optimized candidate modes. As shown in Figure 12, the decoder may first determine a prediction mode of one diagonal angle, i.e., a mode with prediction direction index number 34, as the optimized candidate mode, and then determine any one of modes of another diagonal angle direction with prediction direction index numbers 66 and 2 as the optimized candidate mode.

[0087] In an embodiment of the present application, the decoder may determine a derivative angle mode of at least one diagonal angle mode as an optimized candidate mode. Specifically, when a current chroma block is a square chroma block, i.e., when the diagonal angle mode of the current chroma block is a mode with prediction direction index numbers of 34, 66, and 2, not only more diagonal angle modes are used for prediction, but also other derivative angles close to the diagonal angle mode are used for prediction. Figure 13 is a diagram 2 illustrating establishing optimized candidate modes. As shown in Figure 13, the decoder may first determine a prediction mode of one derivative angle, i.e., a mode with prediction direction index number 32, as the optimized candidate mode, and then determine any one of the modes with prediction direction index numbers 66 and 2 as the optimized candidate mode.

[0088] In an embodiment of the present application, the decoder can first determine at least one derived angle mode. Specifically, the decoder can first determine an index number M corresponding to a DM, where M is an integer greater than 0. Then, the decoder can obtain a transformation parameter N. Finally, the decoder can further determine an index number corresponding to a derived angle mode according to M and N to obtain a derived angle mode, where N is an integer greater than 0.

[0089] In an embodiment of the present application, when a decoder determines an index number corresponding to a derived angular mode according to M and N, it may perform an addition operation on M and N, and a subtraction operation on M and N to finally obtain an index number corresponding to the derived angular mode. Here, the value of N may be 3, 5, or 7. For example, according to FIG. 2 above, if the index number M corresponding to the DM is 0 (i.e., the DM is in planar mode), the decoder may use an angular direction obtained by 0+5 or 0-5 as the index number corresponding to the derived angular mode. Since prediction modes are usually not represented by negative numbers, a specific mapping method may be used to map the calculated value to the valid display range. For example, a specific calculation formula may be (M+62-N)%64+2, which obtains 60. In this case, it is possible to obtain derived angular modes that are prediction direction angle 5 mode and prediction direction angle 60 mode.

[0090] In an embodiment of the present application, since the modes with prediction direction index numbers 66 and 2 belong to two directions of one gradient, the decoder may adjust the mode with prediction direction index number 2 by one angle in a clockwise direction to become the optimized candidate mode. For example, FIG. 14 is drawing 3 illustrating establishing optimized candidate modes. As shown in FIG. 14, the decoder adjusts the mode with prediction direction index number 2 to the mode with prediction direction index number 6. At the same time, the decoder may adjust the mode with prediction direction index number 66 by one angle in a counterclockwise direction to become the optimized candidate mode. For example, FIG. 15 is drawing 4 illustrating establishing optimized candidate modes. As shown in FIG. 15, the decoder adjusts the mode with prediction direction index number 66 to the mode with prediction direction index number 61. Furthermore, the decoder can also simultaneously adjust the mode with prediction direction index number 66 and the mode with prediction direction index number 2 by one angle to become optimized candidate modes. For example, Figure 16 is Figure 5 showing the establishment of optimized candidate modes. As shown in Figure 16, the decoder adjusts the mode with prediction direction index number 66 to the mode with prediction direction index number B, and adjusts the mode with prediction direction index number 2 to the mode with prediction direction index number A.

[0091] In an embodiment of the present application, when a decoder constructs a chroma prediction mode set according to an optimized candidate mode, the diagonal angle modes and the derived angle modes can be freely combined. For example, if a chroma prediction mode set needs to be constructed through three optimized candidate modes, one diagonal angle mode and two derived angle modes can be added to the chroma prediction mode set, two diagonal angle modes and one derived angle mode can be added to the chroma prediction mode set, or two derived angle modes can be added to the chroma prediction mode set, or three diagonal angle modes can be added to the chroma prediction mode set. For example, when a decoder constructs a chroma prediction mode set according to an optimized candidate mode, it can add prediction direction directional modes 6, 61, and 66 to the chroma prediction mode set, prediction direction directional modes 6, 61, and 34 can be added to the chroma prediction mode set, and prediction direction directional modes 6, 61, and 40 can be added to the chroma prediction mode set. The embodiment of the present application is not specifically limited.

[0092] In an embodiment of the present application, for the wide-angle mode of a rectangular block, one direction from the modes with prediction direction index numbers 66 and 2 can be selected as a candidate according to its valid prediction direction range, and the angle corresponding to another number can be adjusted to become a candidate.

[0093] In the chroma intra prediction method according to the present application, a decoder obtains a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, obtains a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block. As can be seen, in this embodiment, after obtaining the DM from the code stream data of the current chroma block, if the DM is a DC mode or a planar mode, the decoder can construct a chroma prediction mode set using the optimized candidate mode, and then reconstruct the current chroma block according to the chroma prediction mode set, thereby solving the problem of low chroma intra prediction accuracy when the DM is a DC mode or a planar mode, and further improving codec efficiency.

[0094] According to the above embodiment, in another embodiment of the present application, FIG. 17 is an exemplary structural diagram 1 of the configuration of a decoder according to an embodiment of the present application, and as shown in FIG. 17, the decoder 1 according to an embodiment of the present application may include an acquisition unit 11, a decoding unit 12, an establishment unit 13 and a receiving unit 14.

[0095] The acquisition unit 11 is configured to acquire a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, to acquire a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block.

[0096] In an embodiment of the present application, the obtaining unit 11 is further configured to obtain a linear mode (LM) corresponding to the current chroma block from the codestream data before obtaining the chroma prediction mode set according to the optimized candidate mode.

[0097] In an embodiment of the present application, the obtaining unit 11 is specifically configured to fill the chroma prediction mode set with the DM and the LM, and fill the chroma prediction mode set according to the optimized candidate mode; In an embodiment of the present application, more specifically, the acquisition unit 11 is configured to fill the chroma prediction mode set with the planar mode and the optimized candidate mode when the DM is the DC mode, and to fill the chroma prediction mode set with the DC mode and the optimized candidate mode when the DM is the planar mode.

[0098] In an embodiment of the present application, the optimization candidate modes include at least one mode, where the index numbers of the prediction directions of the at least one mode are different.

[0099] In an embodiment of the present application, the establishing unit 13 is configured to establish the optimized candidate mode before obtaining a chroma prediction mode set according to the optimized candidate mode.

[0100] In an embodiment of the present application, the establishment unit 13 is specifically configured to determine at least one diagonal angle mode as the optimized candidate mode, or to determine a derived angle angle mode of the at least one diagonal angle mode as the optimized candidate mode, or to determine the at least one diagonal angle mode and a derived angle angle mode of the at least one diagonal angle mode as the optimized candidate mode.

[0101] In an embodiment of the present application, before establishing the optimization candidate mode, the acquisition unit 11 further determines an index number M corresponding to the DM, acquires a transformation parameter N, and determines an index number corresponding to a derived angle mode according to the M and the N; The derived angular modes are configured to be acquired, where M and N are integers greater than 0.

[0102] In an embodiment of the present application, the acquisition unit 11 is specifically configured to perform an addition operation on the M and the N to obtain an index number corresponding to the derived angle mode, or to perform a subtraction operation on the M and the N to obtain an index number corresponding to the derived angle mode.

[0103] In the present embodiment, N includes 3, 5, or 7.

[0104] In the present embodiment, the current chroma blocks include square chroma blocks and non-square chroma blocks.

[0105] In an embodiment of the present application, the receiving unit 14 is configured to receive a video bitstream to obtain codestream data corresponding to a current chroma block before obtaining a DM corresponding to the current chroma block from the codestream data corresponding to the current chroma block.

[0106] In an embodiment of the present application, the decoding unit 12 is configured to obtain a chroma prediction mode set according to an optimized candidate mode, and then perform a decoding process according to the chroma prediction mode set to perform chroma reconstruction on the current chroma block.

[0107] In an embodiment of the present application, the obtaining unit 11 is further configured to perform a decoding process according to the chroma prediction mode set to obtain residual data corresponding to the current chroma block from the codestream data before performing chroma reconstruction on the current chroma block.

[0108] In an embodiment of the present application, the decoding unit 12 is specifically configured to perform chroma intra-prediction decoding on the residual data based on the chroma prediction mode set, and perform chroma reconstruction on the current chroma block.

[0109] In an embodiment of the present application, the acquisition unit 11 is further configured to, after receiving a video bitstream and acquiring the code stream data, if the prediction mode corresponding to the current chroma block acquired by the code stream data has the same prediction mode, acquire a chroma prediction mode set according to the optimized candidate mode, and perform chroma reconstruction on the current chroma block.

[0110] FIG. 18 is an exemplary structural diagram 2 of the configuration of a decoder according to an embodiment of the present application. As shown in FIG. 18, the decoder 1 according to the embodiment of the present application further includes a processor 15, a memory 16 that stores executable instructions from the processor 15, a communication interface 17, and a bus 18 configured to connect the processor 15, the memory 16, and the communication interface 17.

[0111] In the present embodiment, the processor 15 may be at least one of an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a central processing unit (CPU), a controller, a microcontroller, and a microprocessor. It should be understood that other electronic devices may be used to realize the functions of the processor in different devices, and the present embodiment is not specifically limited. The device 1 further includes a memory 16, which can be connected to the processor 15 and is configured to store executable program code, the program code including computer operating instructions. The memory 16 may include a high-speed RAM memory and may also include non-volatile memory, such as at least two disk memories.

[0112] In the present embodiment, bus 18 is configured to connect communication interface 17, processor 15 and memory 16 and for communication between these components.

[0113] In the present embodiment, memory 16 is configured to store instructions and data.

[0114] Further, in an embodiment of the present application, the processor 15 is configured to obtain a DM corresponding to the current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, obtain a chroma prediction mode set according to an optimized candidate mode, wherein the chroma prediction mode set is used to perform chroma reconstruction on the current chroma block.

[0115] In practical applications, the memory 16 may be a volatile memory such as a random-access memory (RAM), or may be a non-volatile memory such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD) or a solid-state drive (SSD), or may be a combination of the above types of memory, and provides instructions and data to the processor 15.

[0116] Furthermore, each functional module in this embodiment may be integrated into one processing unit, each unit may exist physically separately, or two or more units may be integrated into one unit. The integrated units may be implemented in the form of hardware or software functional modules.

[0117] When an integrated unit is implemented in the form of a software functional module and is not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment, in essence or a part that contributes to the prior art, or all 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 a storage medium and includes several instructions for a computer device (which may be a personal computer, a server, a network device, etc.) or a processor to execute all or a part of the steps of the method of this embodiment. The storage medium includes various media that can store program code, such as a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0118] In an apparatus according to an embodiment of the present application, the decoder obtains a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a direct current (DC) mode or a planar mode, obtains a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block. As can be seen, in this embodiment, after obtaining the DM from the code stream data of the current chroma block, if the DM is a DC mode or a planar mode, the decoder can construct a chroma prediction mode set using the optimized candidate mode, and then reconstruct the current chroma block according to the chroma prediction mode set, thereby solving the problem of low chroma intra prediction accuracy when the DM is a DC mode or a planar mode, and further improving codec efficiency.

[0119] An embodiment of the present application provides a first computer-readable storage medium storing a program, which, when executed by a processor, implements the above-described chrominance intra-prediction method.

[0120] Specifically, the program instructions corresponding to the chrominance intra prediction method in this embodiment can be stored in a storage medium such as an optical disk, a hard disk, or a U disk. When the program instructions corresponding to one chrominance intra prediction method in the storage medium are read or executed by an electronic device, obtaining a DM corresponding to the current chroma block from codestream data corresponding to the current chroma block; When the DM is a direct current (DC) mode or a planar mode, obtaining a chroma prediction mode set according to an optimization candidate mode; Here, the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block.

[0121] Those skilled in the art will appreciate that the present application may be provided as a method, a system, or a computer program product. Therefore, the present application may take the form of a hardware embodiment, a software embodiment, or an embodiment that combines software and hardware. Furthermore, the present application may take the form of a computer program product embodied in one or more computer-usable storage media (including, but not limited to, disk memory, optical memory, etc.) that contain computer-usable program code.

[0122] The present application will be described with reference to exemplary implementation flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each process and / or block of the exemplary implementation flowcharts and / or block diagrams, and combinations of the processes and / or blocks of the exemplary implementation flowcharts and / or block diagrams, can be implemented by computer program instructions. To create a machine, these computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device, causing the instructions, executed by the processor of the computer or other programmable data processing device, to generate an apparatus for performing the function(s) specified in one or more processes of the exemplary implementation flowcharts and / or one or more blocks of the block diagrams.

[0123] These computer program instructions may be stored in a computer-readable memory that can cause a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory cause an article of manufacture comprising an instruction apparatus that embodies the functions specified in one or more processes of the exemplary implementation flowcharts and / or one or more blocks of the block diagrams.

[0124] These computer program instructions may also be loaded into a computer or other programmable data processing apparatus and cause the computer or other programmable apparatus to perform a series of operational steps to generate a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more processes of the exemplary implementation flowcharts and / or one or more blocks of the block diagrams.

[0125] The above are only preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. [Industrial Applicability]

[0126]

[0013] The present embodiment provides a chroma intra prediction method, a decoder, and a computer storage medium, in which the decoder obtains a DM corresponding to a current chroma block from code stream data corresponding to the current chroma block, and if the DM is a DC mode or a planar mode, obtains a chroma prediction mode set according to an optimized candidate mode, where the chroma prediction mode set is used to perform chroma reconstruction for the current chroma block. As can be seen, in the present embodiment, after obtaining the DM from the code stream data of the current chroma block, if the DM is a DC mode or a planar mode, the decoder constructs a chroma prediction mode set using the optimized candidate mode, and then reconstructs the current chroma block according to the chroma prediction mode set, thereby solving the problem of low chroma intra prediction accuracy when the DM is a DC mode or a planar mode, and further improving codec efficiency.

Claims

1. 1. A chrominance intra prediction method applied in a decoder, comprising: analyzing codestream data corresponding to a current chroma block and determining that a prediction mode of the current chroma block is direct mode (DM); Determining an optimized candidate mode based on at least one diagonal angle mode, or determining an optimized candidate mode based on a derivative angle mode of the at least one diagonal angle mode, or determining an optimized candidate mode based on at least one diagonal angle mode and a derivative angle mode of the at least one diagonal angle mode; determining a chroma prediction mode set according to the optimized candidate modes; determining a reconstructed value of the current chroma block according to an intra prediction mode; A chroma intra prediction method, wherein when a luminance prediction mode corresponding to the direct mode (DM) is any of a direct current (DC) mode, a planar mode, a vertical (VER) mode, or a horizontal (HOR) mode, the chroma prediction mode set includes a diagonal angle mode having an index number of 66.

2. When a luminance prediction mode corresponding to the direct mode (DM) is a direct current (DC) mode, determining the chroma prediction mode set according to at least a planar mode and the optimization candidate mode; When a luminance prediction mode corresponding to the direct mode (DM) is a planar mode, the chroma prediction mode set is determined according to at least a direct current (DC) mode and the optimization candidate mode. The chrominance intra-prediction method according to claim 1 .

3. 1. A chrominance intra prediction method applied in an encoder, comprising: determining that a prediction mode of a current chroma block is direct mode (DM); Determining an optimized candidate mode based on at least one diagonal angle mode, or determining an optimized candidate mode based on a derivative angle mode of the at least one diagonal angle mode, or determining an optimized candidate mode based on at least one diagonal angle mode and a derivative angle mode of the at least one diagonal angle mode; determining a chroma prediction mode set according to the optimized candidate modes; determining a reconstructed value of the current chroma block according to an intra prediction mode; A chroma intra prediction method, wherein when a luminance prediction mode corresponding to the direct mode (DM) is any of a direct current (DC) mode, a planar mode, a vertical (VER) mode, or a horizontal (HOR) mode, the chroma prediction mode set includes a diagonal angle mode having an index number of 66.

4. When a luminance prediction mode corresponding to the direct mode (DM) is a direct current (DC) mode, determining the chroma prediction mode set according to at least a planar mode and the optimization candidate mode; When a luminance prediction mode corresponding to the direct mode (DM) is a planar mode, the chroma prediction mode set is determined according to at least a direct current (DC) mode and the optimization candidate mode. The chrominance intra-prediction method according to claim 3 .

5. 1. A decoder comprising a processor, a memory storing processor-executable instructions, a communications interface, and a bus connecting the processor, the memory, and the communications interface, A decoder, wherein the processor executes the instructions to implement the chroma intra prediction method of claim 1 or 2.

6. 1. An encoder comprising: a processor; a memory for storing processor-executable instructions; a communication interface; and a bus connecting the processor, the memory, and the communication interface, An encoder, wherein the processor executes the instructions to implement the chroma intra prediction method of claim 3 or 4.

7. A computer-readable storage medium having instructions and code streams stored thereon, comprising: A computer-readable storage medium, the instructions of which, when executed by a processor, implement the steps of the method of claim 1 or 2 to decode the codestream to generate video.

8. A computer-readable storage medium having instructions and code streams stored thereon, comprising: A computer-readable storage medium, the instructions of which, when executed by a processor, implement the steps of the method of claim 3 or 4 to generate the codestream.

Images