WO2013113217A1

WO2013113217A1 - Decoding method and device

Info

Publication number: WO2013113217A1
Application number: PCT/CN2012/080343
Authority: WO
Inventors: 杨海涛; 李斌; 李厚强
Original assignee: 华为技术有限公司; 中国科学技术大学
Priority date: 2012-01-31
Filing date: 2012-08-20
Publication date: 2013-08-08
Also published as: CN103227917A; CN103227917B

Abstract

Embodiments of the present invention provide a decoding method and device. The method comprises: extracting chrominance component mode information in a code stream, the chrominance component mode information being used for determining a chrominance component intra-frame prediction mode; determining a chrominance component intra-frame prediction mode according to the chrominance component mode information; when it is determined that the chrominance component intra-frame prediction mode is a DM mode, extracting residual prediction information in the code stream; and performing a chrominance component prediction operation according to the residual prediction information, so as to obtain a chrominance component intra-frame prediction signal. The technical solution, by means of different identification methods of the RM mode and DM mode in a code stream, shortens the length of a code word carrying the chrominance component prediction mode information, thereby reducing the complexity of decoding on mode information, and achieving the purposes of removing redundant information in RM mode information and in cbf information of a brightness component, and improving the compression efficiency of a video image.

Description

Decoding method and device

The present invention relates to the field of video image processing and, more particularly, to a decoding method and apparatus. Background technique

Existing video image coding and decoding technologies include intra coding techniques and interframe coding techniques. Intra coding refers to a technique of compressing and encoding image content using only spatial correlation in the current encoded image. Inter-frame coding refers to a technique of compression-encoding a current picture using the temporal correlation of the current coded picture with the coded picture. To improve the intraframe coding efficiency of images, the H.264/AVC (Advanced Video Coding, Advanced Video Coding) standard introduces intra prediction techniques for the first time to remove spatial information redundancy between currently coded image blocks and adjacent coded image blocks. Therefore, unlike the previous intraframe coding technique, H.264/AVC only needs to perform spatial transform and entropy coding on the prediction difference signal instead of the original image signal, thereby improving the intra coding efficiency.

A video image signal typically includes one luminance component and two chrominance components. HEVC ( High

The Efficiency Video Coding, a highly efficient video coding scheme, is a new generation of video coding standardization scheme currently being studied by the International Organization for Standardization. It inherits the intra prediction coding technique in the H.264/AVC standard and introduces new features for chrominance components. Intra prediction mode LM mode. When the LM mode is used, the chrominance component prediction value of the image block is calculated by the linear model from the reconstructed value resampled by the luminance component of the corresponding block. Therefore, the LM mode is different from the conventional directional intra prediction mode in that it uses the correlation between the luminance component and the chrominance component of the image signal, and uses the luminance component value to predict the chrominance component value.

The HEVC scheme inherits and extends the intra prediction coding technique in the H.264/AVC standard. The image block chrominance component includes all selectable intra prediction modes to form a prediction mode set, which is called a chrominance component intra prediction mode set, and includes the following six prediction modes:

DM mode: using the intra prediction mode of the luminance component of the current block as a prediction mode of the chrominance component, and performing prediction;

LM mode: The predicted value of the chroma component is calculated based on the value of the sampled point luminance component based on the linear model, and the linear model parameter is calculated from the luminance component value and the chroma component value of the sample point adjacent to the current block;

DC mode: Use the average of the values of the chroma components of the sample points adjacent to the current block as the current a predicted value of the block chrominance component;

Plane (Planar) mode: Calculate the predicted value of the current block sample point based on the assumption that the value of the sample point changes linearly in space;

Horizontal mode: use the value of the chrominance component of the adjacent sampling point on the left side as the predicted value of the chrominance components of all sampling points in the same row of the current block;

Vertical mode: Use the value of the chroma component adjacent to the sample point directly above as the predicted value of the chroma component of all samples in the same column of the current block.

In addition to the above prediction mode, there is also a substitute mode. If the DM mode is the same as the remaining prediction modes in the prediction mode set, the same chrominance prediction mode as the DM mode is replaced with the replacement mode to form a new prediction mode set. The alternate mode may be a prediction mode that is different from all of the modes in the chroma component prediction mode set.

With the development of technology, an improved chromaticity prediction mode, that is, the RM mode, has appeared for the above DM mode. The difference between the RM mode and the DM mode is whether or not the luminance component residual signal is used to assist the chrominance component for intra prediction. In addition, a similar type of chroma prediction mode appears for the above LM mode, and the chroma prediction modes of this class are collectively referred to as the LM class mode hereinafter. In the related art, the TU (Truncated Unary) code scheme is used for encoding and decoding the above-mentioned chrominance prediction modes, which increases the codeword length of the chrominance prediction mode, and the long TU code causes the decoding efficiency to decrease. Summary of the invention

Embodiments of the present invention provide a decoding method and apparatus, which can improve decoding efficiency.

In one aspect, a decoding method is provided, including: extracting chroma component mode information in a code stream, the chroma component mode information is used to determine a chroma component intra prediction mode; and determining a chroma component according to chroma component mode information. An intra prediction mode; when determining that the chroma component intra prediction mode is the DM mode, extracting residual prediction information in the code stream; performing a chroma component prediction operation according to the residual prediction information to obtain a chroma component intra prediction signal, The DM mode refers to a mode in which an intra prediction operation is performed on a chroma component using a prediction method specified by a luma component intra prediction mode, and the luma component intra prediction mode refers to a luminance acquired from a code stream in a luminance component decoding process. The luminance component prediction mode determined by the component mode information.

In another aspect, a decoding apparatus is provided, including a first extracting unit, a first determining unit, a second extracting unit, and an operating unit, wherein the first extracting unit is configured to extract a chroma component in the code stream The mode information, the chroma component mode information is used to determine a chroma component intra prediction mode; the first determining unit is configured to determine a chroma component intra prediction mode according to the chroma component mode information extracted by the first extracting unit; a unit, configured to: when the first determining unit determines that the chroma component intra prediction mode is

In the DM mode, the residual prediction information in the code stream is extracted; the operation unit is configured to perform a chroma component prediction operation according to the residual prediction information extracted by the second extraction unit to obtain a chroma component intra prediction signal, where the DM mode refers to A mode of performing an intra prediction operation on a chroma component using a prediction method specified by a luma component intra prediction mode, and a luma component intra prediction mode refers to determining, according to luma component mode information acquired from a code stream, in a luma component decoding process Luminance component prediction mode.

The above technical solution shortens the codeword length of the chrominance component prediction mode information by using different identification methods of the RM mode and the DM mode in the code stream, thereby reducing the complexity of decoding on the mode information, and thereby removing the RM mode information and The redundant information of the cbf information of the luminance component improves the compression efficiency of the video image. DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. Other drawings may also be obtained from those of ordinary skill in the art in view of the drawings.

FIG. 1 is a schematic flow chart of a method of decoding according to an embodiment of the present invention.

2 is a schematic flow chart of a method of decoding according to another embodiment of the present invention.

3 is a schematic flow chart of a method of decoding according to still another embodiment of the present invention.

4 is a schematic block diagram of a decoding apparatus according to an embodiment of the present invention.

Figure 5 is a schematic block diagram of a decoding apparatus according to another embodiment of the present invention. detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without making creative labor are within the scope of the present invention.

The term "and/or" in this context is merely an association describing the associated object, indicating that there may be three relationships, for example, A and / or B, which may mean: A exists separately, and A and B exist simultaneously. There are three cases of B alone. In addition, the character "/" in this article generally indicates that the contextual object is an "or" relationship.

The chrominance component in the embodiment of the present invention may refer to any one of the two chrominance components. For example, when the chrominance prediction mode set includes the DM mode, the LM mode, the DC mode, the vertical mode, the horizontal mode, and the planar mode, the chrominance coding scheme in the related art uses the TU code to perform binary value on the mode information of the current block. Then, the binarized binary symbols are entropy encoded using CABAC (Context Cased Binary Arithmetic Coding) technology. For example, in the HE (High Efficiency) configuration, the DM, LM, Vertical, Horizontal, DC, and Plane modes can be represented by the TU code words 0, 10, 110, 1110, 11110, 11111, respectively; (Low Complexity, low complexity) configuration, DM, vertical, horizontal, DC and plane modes can be represented by TU code words 0, 10, 110, 1110, 1111 respectively. The decoding end determines the prediction mode of the current block chrominance component based on the parsed TU codeword.

The RM mode is the same as the DM mode in that the intra-prediction operation is performed on the chroma component by the prediction method specified by the luma component prediction mode to obtain the chroma component prediction signal. The difference from the DM mode is that the RM mode further uses the luminance component residual signal to assist the chrominance component for prediction. The RM mode determines a residual prediction factor according to the information obtained from the code stream, and calculates a residual prediction correction signal according to the luminance component residual signal and the residual prediction factor, and then uses the residual prediction correction signal pair according to the DM mode prediction method. The acquired chroma component intra prediction signal is corrected.

The RM mode, along with other selectable chroma modes, encodes the mode information using the TU code. For example, if other selectable modes include DM, LM, vertical, horizontal, DC, and planar modes, the TU code words 0, 10, 110, 1110, 11110, 111110, 111111 can be used to represent DM, LM, RM, horizontal, respectively. , vertical, DC and flat mode. Obviously, the mapping relationship between the set of codewords used and the set of patterns used can also be changed to obtain a new scheme. In addition, you can also reduce the number of optional modes to get a new solution. For example, the horizontal and vertical modes can be removed to obtain a new set of selectable chroma prediction modes, and a set of TU codes is used to represent the set of selectable chroma modes.

The LM class mode represents such a set of chrominance prediction modes, which are similar to the LM technique in the background art, and are based on the linear model to calculate the predicted values of the chrominance components using the values of the sampled point luminance components, which differ in that different ones are selected. The linear model parameters are calculated adjacent to the sampling points. The LM class mode can include one or more modes. The LM mode refers specifically to the LM mode in the background art.

For example, the LM mode is improved to obtain the LML mode and the LMA mode. Among them, LML mode The model calculates the model parameters using only the reconstructed values of the adjacent sample points on the left side of the current block, while the LMA uses only the reconstructed values of the adjacent sample points above the current block to calculate the model parameters. At this time, the LM class mode includes three modes of LM mode, LMA mode, and LML mode.

Other improved modes of the LM mode are also available depending on the selection of adjacent sampling points. For example, all adjacent sampling points can be divided into a first set of sampling points and a second set of sampling points that are not mutually exclusive. The LM mode using the first set of sampling points can be recorded as LM1, and the LM mode using the second set of sampling points can be recorded as LM2. This can also be used to replace the original LM mode in the background art with LM1 mode and LM2 mode. At this time, the LM class mode includes two modes, LM1 and LM2.

All LM class modes, along with other chroma prediction modes, encode the mode information using a TU code (Truncated Unary Code). For example, if the LM class mode includes LM, LML and LMA, the TU code words 0, 10 can be used when these three modes are used together with the existing DM, horizontal, vertical, DC and plane modes in the background art. 110, 1110, 11110, 111110, 1111110, 1111111 represent DM, LM, LMA, LML, horizontal, vertical, DC, and planar modes, respectively. For another example, if the LM class mode includes LM1 and LM2, the TU code words 0, 10, 110 can be used when the two modes are used together with the existing DM, horizontal, vertical, DC and plane modes in the background art. , 1110, 11110, 111110, 111111 represent DM, LM1, LM2, horizontal, vertical, DC, and planar modes, respectively. Obviously, the mapping relationship between the set of codewords used and the set of patterns used can also be changed to get a new scheme. In addition, one or more modes can be removed from all of the above alternative modes to obtain a new solution. For example, the horizontal and vertical modes can be removed to obtain a new set of selectable chroma prediction modes, and a set of TU codes is used to represent the set of selectable chroma modes.

When the set of chroma prediction modes includes DM, RM, LM class, horizontal, vertical, DC, and planar modes, the efficiency of decoding using the TU code is low.

In addition, the RM mode information and the cbf (coded block flag) information of the luminance component are redundant. The cbf information of the luminance component indicates whether a luminance component of the current block has a non-zero transform coefficient. Since the presence of a non-zero transform coefficient means that the residual signal is not all zero, the absence of a non-zero transform coefficient means that the residual signal is all zero. On the one hand, the only difference between the RM mode and the DM mode is whether or not the luminance component residual signal is used to assist the chrominance component for intra prediction. Obviously, selecting to use the RM mode instead of the DM mode means that the luminance component residual signal is not all zero. Therefore, the RM mode information and the cbf information of the luminance component are redundant. For example, if the RM mode is selected, the cbf value of the luminance component can be inferred without obtaining the cbf information of the luminance component from the code stream. On the other hand, the RM mode is very similar to the DM mode, the only difference being whether to use the luminance component residual signal to assist The chrominance component is intra predicted. Encoding two highly similar modes as separate two modes increases the codeword length of the remaining modes, while a long TU codeword reduces the efficiency of entropy decoding.

As an improvement to the above technical solution, an embodiment of the present invention provides a decoding method and apparatus.

In the embodiment of the present invention, when the binary symbol is entropy decoded, the context model may be omitted, or a context model may be used, and a context model may be selected from the plurality of context models according to the encoding information of the neighboring block. The binary symbol includes each of the TU code or the FL code. For example, one TU codeword 110 includes three binary symbols having a value of 1, 1, 0, and one FL codeword 10 includes two binary symbols having a value of 1, 0.

It should be noted that entropy decoding of a binary symbol without using a context model is a prior art technique, namely the equal probability (in-pass) mode in CABAC technology. It is a prior art to entropy decode a binary symbol using a context model. For example, the first flag in the luminance intra-frame coding and decoding scheme of HEVC uses this entropy decoding method. It is a prior art to select a context model from a plurality of context models for entropy decoding according to the coding information of the neighboring block. For example, the skip mode flag in the HEVC scheme (the skip flag in English) adopts this entropy decoding method. Therefore, the details of the above three entropy decoding methods are not described again.

FIG. 1 is a schematic flow chart of a method 10 of decoding according to an embodiment of the present invention, including the following.

11 . Extract chroma component mode information in the code stream. Chroma component mode information

12. Determine a chroma component intra prediction mode according to the chroma component mode information.

13. When the chroma component intra prediction mode is the DM mode, the residual prediction information in the code stream is extracted.

14. Perform a chroma component prediction operation based on the residual prediction information to obtain a chroma component intra prediction signal.

Wherein, the DM mode refers to a mode in which an intra prediction operation is performed on a chroma component using a prediction method specified by a luma component intra prediction mode, and the luma component intra prediction mode refers to a process in which the luma component is decoded from the code stream. The obtained luminance component prediction mode determined by the luminance component mode information.

In the embodiment of the present invention, the different identification methods in the code stream by the RM mode and the DM mode shorten the codeword length of the chrominance component prediction mode information, thereby reducing the complexity of decoding on the mode information, and thereby removing the RM mode. The redundant information of the cbf information of the information and the luminance component improves the compression efficiency of the video image. 2 is a schematic flow chart of a decoding method 200 according to another embodiment of the present invention, including the following.

210. Extract chroma component mode information in the code stream, where the chroma component mode information is used to determine a chroma component intra prediction mode.

The chrominance component mode information may include one or more pieces of information by classifying the patterns in the chrominance component intra prediction mode set.

For example, the chroma component mode information may include only one information carried by the TU code, the information having a one-to-one correspondence with the patterns in the intra-prediction mode set of the chroma components. For example, TU code words 0, 10, 110, 1110, 11110, 111110, 1111110, 1111111 may be used to represent DM, LM, LMA, LML, horizontal, vertical, DC, and planar modes, respectively, in the context Also known as the fourth TU code. By extracting the fourth TU code, the intra-frame prediction mode of the chroma component can be determined.

Optionally, the chroma component mode information may include first information indicating whether the chroma component intra prediction mode is a DM mode or an LM class mode. In addition, when it is determined that the chroma component intra prediction mode is neither the DM mode nor the LM class mode according to the first information, the chroma component mode information may further include second information for indicating the chroma component. a remaining mode of an intra prediction mode, the remaining mode being one of available for a chroma component intra prediction mode other than a mode that the first information may determine. For example, if the chroma component intra prediction mode set further includes vertical, horizontal, DC, and planar modes, the remaining mode is one of them. If it is determined that when the chroma component intra prediction mode is neither the DM mode nor the LM class mode but the default specific mode, the second information is not included in the encoding, and accordingly, the second information is not extracted during decoding. . For convenience of explanation, this default specific mode is also referred to as the first default mode.

Both the first information and the second information may be carried by a fixed length (FL, fixed length) code or a TU code. The first information may include a one-bit binary symbol. When the context is also referred to as a second fixed length code, the second fixed length code may use the binary symbols 1, 0 to respectively indicate that the chroma component intra prediction mode is DM. The mode, the chroma component intra prediction mode is not the DM mode. A binary symbol can be either 0 or 1, so it can represent two cases. Obviously, the new implementation method can be obtained by changing the correspondence between the binary symbol values and the represented cases. For example, the binary symbol values 0 and 1 may be used to indicate that the chroma component intra prediction mode is the DM mode and the chroma component intra prediction mode is not the DM mode. In the following description, when one bit binary symbol is used to determine one of the two cases, the specific correspondence will not be given. Alternatively, the first information is carried by a maximum two-bit TU code, also referred to as a first TU code in the context. For example, the TU code words 0, 10, and 11 may be used to indicate that the chrominance component intra prediction mode is the DM mode, the chrominance component intra prediction mode is the LM class mode, and the chrominance component intra prediction mode is It is not the DM mode and the LM class mode. A TU codeword consists of one or more binary symbols, for example TU codeword 10 consists of binary symbol 1 and binary symbol 0. If all binary symbol values in a set of TU codewords are inverted at the same time, the resulting set of codewords is still a TU codeword. For example, codewords 1, 01, 00 are still a set of TU codewords. In addition, it is obvious that a new implementation method can be obtained by changing the mapping relationship between a set of TU code words and the represented situation. For example, the TU code words 0, 10, and 11 may also be used to indicate that the chrominance component intra prediction mode is the LM class mode, the chrominance component intra prediction mode is the DM mode, and the chrominance component intra prediction. The mode is neither the DM mode nor the LM class mode. In the following description, when a set of TU code words is used to determine one of a plurality of cases, each of the possible correspondences will not be exhaustive.

Optionally, an implementation method of step 210 is as follows: extracting a second fixed length code from the code stream. Determining, by the second fixed length code, whether the chroma component intra prediction mode is a DM mode; if determining, according to the second fixed length code, that the chroma component intra prediction mode is not a DM mode, further determining the The chroma component intra prediction mode, in which case the first information may further include another one bit binary symbol, a third fixed length code. This content can be explained later with reference to FIG. If the third fixed length code is not included in the first information at this time, it indicates that the chroma component prediction mode cannot be determined from the first information, and the second information needs to be further extracted and the chroma component prediction mode is determined according to the second information.

Optionally, another implementation manner of step 210 is described as follows: extracting the first from the code stream

And a TU code, determining, according to the first TU code, whether the chroma component intra prediction mode is a DM mode or an LM mode, or neither a DM mode nor an LM mode.

220. The chroma component mode information determines whether the chroma component intra prediction mode is a DM mode. According to the foregoing, it is determined that the chroma component intra prediction mode is the DM mode, that is, "YES" of 220 of Fig. 2, then the process proceeds to step 230. If it is determined that it is not the DM mode, that is, "No" of 220 of Fig. 2, refer to 310 of Fig. 3 and its subsequent contents.

230. Extract residual prediction information in the code stream.

The block prediction (cbf) information may be encoded in the extracted luma component, and the cbf information is determined to indicate that the current block luma component includes non-zero coefficients, and residual prediction information in the code stream is extracted. This removes the redundancy of residual prediction information and cbf information.

The residual prediction information may include a binary character indicating the residual prediction flag information. The number, that is, the first fixed length code in the context, the residual prediction flag information is used to indicate whether the luminance component residual signal is used to assist the chrominance component for the prediction operation. At this time, step 230 is specifically configured to extract a first fixed length code from the code stream.

240. Determine, according to the first fixed length code, whether the residual prediction flag information indicates that the luma component residual signal is used to perform a prediction operation using the luma component residual signal. When it is determined that the luminance component residual signal is not used, that is, "NO" of 240 of Fig. 2, it proceeds to step 250.

250. Determine a DM mode as a chroma component intra prediction mode.

When it is determined that the indication uses the luminance component residual signal, that is, "YES" of 240 of Fig. 2, then step 260 is reached. If the residual prediction factor is the default value, or the residual prediction factor is calculated by the decoding end, step 260 may be omitted, and step 270 is directly performed.

260. Extract residual residual prediction factor information from the code stream, where the residual prediction factor determined by the residual prediction factor information is used to specify how to use a luminance component residual signal to assist a chrominance component for performing a prediction operation, where the brightness The component residual signal refers to the signal generated during the decoding of the luminance component.

For a set of residual predictors, each of the residual predictors may be assigned an index value, and the TU code or FL code or other coding scheme may be selected to represent the set of index values, where the residual predictor The information is carried by the code words in the selected coding scheme.

270. Calculate a residual prediction correction signal according to the residual prediction factor and the luminance component residual signal.

280. Perform an intra prediction operation on the chroma component by using a prediction method specified by the chroma component intra prediction mode to obtain a chroma component intra prediction signal.

The order of execution of the steps 270 and 280 is interchangeable, and the present invention does not limit this. 290. Correct the chrominance component intra prediction signal by using the residual prediction correction signal to obtain a modified chrominance component intra prediction signal.

The correction method used may be to superimpose the chroma component intra prediction signal acquired in accordance with the DM mode prediction method and the residual prediction correction signal. Alternatively, the residual prediction correction signal used may be obtained by appropriately scaling the product of the luminance component residual signal. Optionally, the luminance component residual signal may be obtained by an appropriate resampling operation by a difference signal between the luminance component sample point reconstruction signal and the luminance component sample point prediction signal, or may be inverse quantized and inversely performed by the luminance transform coefficient signal. Operations such as transformation and resampling are obtained. When the position of the luminance component sampling point is different from the sampling position of the chrominance component, the above resampling operation is required to obtain the luminance component of the chrominance component sampling point position. Sample value.

After step 250, step 280 is also performed as a prior art, and subsequent image processing takes as input the chroma component intra prediction signal obtained by performing an intra prediction operation on the chroma component using the DM mode.

In the embodiment of the present invention, after step 260 and step 270, combined with step 280, and finally by step 290, the intra-prediction operation is actually performed on the chroma component in the RM mode, and the subsequent image processing is performed on the corrected chroma component. The intra prediction signal is used as an input. In the embodiment of the present invention, in order to avoid confusion, the execution method of the RM mode is highlighted, and the connection between step 250 and step 280 is omitted in FIG.

In the embodiment of the present invention, different identification methods of the RM mode and the DM mode in the code stream shorten the codeword length of the chrominance component prediction mode information, thereby reducing the complexity of decoding on the mode information, and thereby removing the RM mode information. Redundant information existing in the cbf information of the luminance component improves the compression efficiency of the video image.

FIG. 3 is a schematic flowchart of a decoding method 300 according to another embodiment of the present invention.

Different from the embodiment of FIG. 2, the embodiment of the present invention mainly describes how to decode all the optional chroma component intra prediction modes after performing block coding.

It has been explained in Fig. 2 that the chrominance component prediction mode information may include first information and/or second information. As shown in FIG. 3, the embodiment of the present invention does not exclude the case where the chroma component prediction mode information includes only one fourth TU code. Method 300 includes the following.

305. Extract the first information in the code stream.

310. Determine that the chroma component intra prediction mode is not the DM mode.

If it is determined by the second fixed length code in the first information that the chroma component intra prediction mode is not the DM mode, step 320 is performed. Alternatively, optionally, when the chrominance component intra prediction mode does not include the LM class mode, if the chrominance component intra prediction mode is not the DM mode by using the second fixed length code in the first information, Go to step 350. It is usually known before encoding whether the LM class mode is included in the chroma component intra prediction selectable mode. When the LM class mode is not included, the following third fixed length code does not appear in the encoding. In another implementation manner, the codeword corresponding to the LM class mode will not be included in the TU code, and the decoding end will be omitted. Extraction step.

320. Extract a third fixed length code in the first information, and determine, by the third fixed length code, whether it is an LM class mode.

It is also possible to directly determine that the DM mode is not through the first TU code in the first information, if

The LM class mode then proceeds to step 330, which is "yes" of step 320. Or, you can pass If the first TU code in a message directly determines that it is not the DM mode or the LM mode, step 350 is performed, or step 380, that is, "No" of step 320.

Usually, before encoding, it is known that the LM class mode has only one default mode, or the mode in the LM class mode set is a fixed plurality of modes, so when the LM class mode includes only one default mode, optional, execution steps 370, the default mode context is referred to as a second default mode. The LM class mode information can be omitted at the time of encoding, and accordingly, the LM class mode information is not extracted when decoding.

370. When it is determined to be the LM class mode, and the LM class mode includes only the second default mode, the second default mode is used as the chroma component intra prediction mode.

Or, 330, when it is determined to be the LM class mode, extract LM class mode information from the code stream. 340. Determine the chroma component intra prediction mode according to the LM class mode information.

Similar to the first information or the second information, the LM class mode information can also be carried by the FL code or TU code of the binary symbol. As described above, when the LM class mode includes the first LM class mode and the second LM class mode, a binary character representing the LM class mode information may be extracted from the code stream, that is, in the context. The fourth fixed length code determines, according to the fourth fixed length code, that the chroma component intra prediction mode is the first LM class mode or the second LM class mode.

When the LM class mode includes three modes of a first LM class mode, a second LM class mode, and a third LM class mode, the LM class mode information includes a fifth fixed length code and a sixth fixed length code. Extracting, from the code stream, the fifth fixed length code in the LM class mode information, and determining, according to the fifth fixed length code, whether the chroma component intra prediction mode is a first LM class mode; And the chrominance component intra prediction mode is not the first LM class mode, further extracting a sixth fixed length code in the LM class mode information from the code stream, and determining the color according to the sixth fixed length code The degree component intra prediction mode is a second LM class mode or a third LM class mode.

Optionally, when the LM class mode includes three modes: a first LM class mode, a second LM class mode, and a third LM class mode, the LM class mode information is carried by the second TU code. Extracting, by the code stream, the second TU code, determining, according to the second TU code, whether the chroma component intra prediction mode is the first LM class mode, or the second LM class mode, or For the third LM class mode. For example, when the second TU is 0, 10, and 11, respectively, the intra chroma prediction mode corresponding to the chroma component is the first LM class mode, the second LM class mode, and the third LM class mode.

The first and second serial numbers in the embodiments of the present invention are only for the convenience of explanation, and the same things are distinguished, and the content of the things themselves is not limited.

350: Extract the second information when it is determined that neither the DM mode nor the LM mode is determined. 360: Determine a chroma component intra prediction mode by using the second information.

The first to sixth fixed length FL codes can maximize the efficiency of decoding if they are a binary symbol. When the second information is carried by a seventh fixed length FL code, the seventh fixed length code is extracted from the code stream, and the chrominance component intra prediction is determined according to the seventh fixed length FL code. mode. When the second information indicates one of the four remaining modes, the seventh fixed length code herein may be a two-bit FL code, for example, the following correspondence may exist. When the seventh fixed length code is 00, 01, 10, and 11, the intra-prediction modes of the chroma component are respectively indicated as horizontal, vertical, DC, and planar modes. Thereby, the chroma component intra prediction mode can be determined.

Optionally, when the second information is carried by the third TU code, extracting the third TU code from the code stream, and determining the chroma component intra prediction mode according to the third TU code. For example, when the third TU code is 0, 10, 110, and 111, the intra-prediction modes of the chroma component are respectively indicated as horizontal, vertical, DC, and planar modes. Thereby, the chroma component intra prediction mode can be determined.

Alternatively, step 380 can replace steps 350 and 360.

380. When the chroma component intra prediction mode is neither the DM mode nor the LM class mode, but the first default mode, the first default mode is used as the chroma component intra prediction mode. In the embodiment of the present invention, the method for group identification of the chrominance component intra prediction mode in the code stream shortens the codeword length of the chrominance component prediction mode information, thereby reducing the complexity of decoding on the mode information, and improving the compression of the video image. The purpose of efficiency.

Figure 4 is a schematic block diagram of a decoding device 40 in accordance with an embodiment of the present invention.

The apparatus 40 includes a first extraction unit 41, a first determination unit 42, a second extraction unit 43, and an operation unit 44.

The first extracting unit 41 is configured to extract chroma component mode information in the code stream, and the chroma component mode information is used to determine a chroma component intra prediction mode.

The first determining unit 42 is configured to determine a chroma component intra prediction mode according to the chroma component mode information extracted by the first extracting unit 41.

The second extracting unit 43 is configured to extract residual prediction information in the code stream when the first determining unit 42 determines that the chroma component intra prediction mode is the DM mode.

The operation unit 44 is configured to perform a chroma component prediction operation according to the residual prediction information extracted by the second extraction unit 43 to acquire a chroma component intra prediction signal.

Wherein the DM mode refers to a mode in which an intra prediction operation is performed on a chroma component using a prediction method specified by a luma component intra prediction mode, and the luma component intra prediction mode refers to a luma subdivision In the amount decoding process, the luminance component prediction mode is determined based on the luminance component mode information acquired from the code stream.

In the embodiment of the present invention, the different identification methods in the code stream by the RM mode and the DM mode shorten the codeword length of the chrominance component prediction mode information, thereby reducing the complexity of decoding on the mode information, and thereby removing the RM mode. The redundant information of the cbf information of the information and the luminance component improves the compression efficiency of the video image.

Figure 5 is a schematic block diagram of a decoding device 50 in accordance with another embodiment of the present invention. The first extraction unit 51, the first determination unit 52, the second extraction unit 53, and the operation unit 54 of the device 50 are the same as the first extraction unit 41, the first determination unit 42, the second extraction unit 43, and the operation unit 44 of the device 40. Or similar. The difference is that the second extraction unit 53 specifically includes an extraction module 531 and a determination module 532. The operation unit 54 specifically includes an operation module 541, a calculation module 542, and a correction module 543.

The first extracting unit 51 is configured to extract chroma component mode information in the code stream, and the chroma component mode information is used to determine a chroma component intra prediction mode.

The first determining unit 52 is configured to determine a chroma component intra prediction mode according to the chroma component mode information extracted by the first extracting unit 51.

The second extracting unit 53 is configured to extract residual prediction information in the code stream when the first determining unit 52 determines that the chroma component intra prediction mode is the DM mode.

The operation unit 54 is configured to perform a chroma component prediction operation according to the residual prediction information extracted by the second extraction unit 53 to acquire a chroma component intra prediction signal.

Wherein the DM mode refers to a mode in which an intra prediction operation is performed on a chroma component using a prediction method specified by a luma component intra prediction mode, and the luma component intra prediction mode refers to a process in which the luma component is decoded, according to the The luminance component prediction mode determined by the luminance component mode information acquired in the code stream.

When the residual prediction information includes residual prediction flag information, the extracting module 531 is configured to extract, from the code stream, a first fixed length code indicating residual prediction flag information, and the residual prediction flag information. Determining whether to use the luma component residual signal to assist the chroma component for performing a prediction operation. The determining module 532 is configured to determine that the residual prediction flag information indicates that the luma component residual signal is used to perform a prediction operation using the luma component residual signal. The extraction module 531 further extracts residual prediction factor information from the code stream, and the residual prediction factor determined by the residual prediction factor information is used to specify how to use the luminance component residual signal to assist the chrominance component for prediction operation, Wherein the luminance component residual signal refers to a signal calculated and generated during the decoding of the luminance component. The operation module 541 is configured to perform an intra prediction operation on the chroma component by using a prediction method specified by the chroma component intra prediction mode to obtain a chroma component intra prediction signal;

The calculation module 542 is configured to calculate a residual prediction correction signal according to the residual prediction factor determined by the determining module 532 and the luminance component residual signal acquired by the operation module 541;

The correction module 543 is configured to modify the chroma component intra prediction signal by using the residual prediction correction signal obtained by the calculation module 542 to obtain a modified chroma component intra prediction signal.

The second extracting unit is specifically configured to: after the chroma component mode information in the extracted code stream, or after extracting the luma component coding block flag cbf information in the code stream, extract residual prediction in the code stream information.

Optionally, the first extracting unit 51 is specifically configured to extract the first information included in the chroma component mode information in the code stream, where the first determining unit 52 is specifically configured to determine the chroma component according to the first information. Intra prediction mode. When the chrominance component intra prediction mode cannot be determined according to the first information, the first extracting unit 51 further extracts second information included in the chrominance component mode information in the code stream, where the first determining unit Determining, according to the second information, the chroma component intra prediction mode, where the first information includes information indicating whether the chroma component intra prediction mode is a DM mode or an LM class mode, The second information is used to indicate a remaining mode as the chroma component intra prediction mode, the remaining mode being one of available for the chroma component intra prediction mode except the mode that the first information may determine And the LM class mode includes one or more modes for calculating a chroma component prediction value using the luma component reconstruction value based on the correlation model.

Optionally, when the first information includes the second fixed length code, the first extracting unit 51 is specifically configured to extract the second fixed length code from the code stream, where the first determining unit 52 Specifically, it is used to determine, according to the second fixed length code, whether the chroma component intra prediction mode is a DM mode.

Optionally, when the first information further includes a third fixed length code, if the first determining unit 52 determines the chrominance component according to the second fixed length code extracted by the first extracting unit 51 If the intra prediction mode is not the DM mode, the first extracting unit 51 further extracts the third fixed length code from the code stream, and the first determining unit 52 determines the according to the third fixed length code. Whether the chroma component intra prediction mode is the LM class mode. If the first determining unit 52 determines that the chroma component intra prediction mode is the LM class mode, the chroma component intra prediction mode needs to be further determined. If the first determining unit 52 determines that the chroma component intra prediction mode is not an LM class mode The equation indicates that the chroma component intra prediction mode cannot be determined according to the first information.

Optionally, when the first information is carried by the first truncated one-dimensional TU code, the first extracting unit 51 is specifically configured to extract the first TU code from the code stream, where the first determining unit is Determining, according to the first TU code, whether the chroma component intra prediction mode is a DM mode or an LM class mode. If the first determining unit 52 determines that the chroma component intra prediction mode is the LM class mode, the chroma component intra prediction mode needs to be further determined. Alternatively, if the first determining unit 52 determines that the chroma component intra prediction mode is neither the DM mode nor the LM class mode, it indicates that the chroma component intra prediction mode cannot be determined according to the first information.

If the first determining unit 52 determines that the chroma component intra prediction mode is the LM class mode, the chroma component intra prediction mode needs to be further determined, and the first extracting unit 51 further extracts the LM from the code stream. Based on the class mode information, the first determining unit 52 determines the chroma component intra prediction mode according to the LM class mode information.

Optionally, when the LM-type mode includes the first LM-type mode and the second LM-type mode, the first extraction module is specifically configured to extract, from the code stream, a fourth LM-type mode information. The first length determining unit 52 determines, according to the LM class mode information, that the chroma component intra prediction mode is the first LM class mode or the second LM class mode.

Optionally, when the LM class mode includes three modes: a first LM class mode, a second LM class mode, and a third LM class mode, and the LM class mode information includes a fifth fixed length code and a sixth fixed length The first extracting unit 51 is specifically configured to extract the fifth fixed length code in the LM type mode information from a code stream, where the first determining unit 52 determines according to the fifth fixed length code. Whether the chroma component intra prediction mode is the first LM class mode. If the first determining unit 52 determines that the chroma component intra prediction mode is not the first LM class mode, the first extracting unit 51 further extracts the sixth setting in the LM class mode information from the code stream. Long code, the first determining unit 52 determines, according to the sixth fixed length code, that the chroma component intra prediction mode is a second LM class mode or a third LM class mode.

Optionally, when the LM class mode includes three modes: a first LM class mode, a second LM class mode, and a third LM class mode, and the LM class mode information is carried by the second TU code, the An extracting unit 51 extracts the second TU code from the code stream, and the first determining unit 52 determines, according to the second TU code, whether the chroma component intra prediction mode is the first LM class mode, Or for the second LM class mode, or for the third LM class mode.

Optionally, when the second information is carried by a seventh fixed length FL code, the first extraction The unit 51 specifically extracts the seventh fixed length FL code from the code stream, and the first determining unit 52 determines the chroma component intra prediction mode according to the seventh fixed length FL code.

Optionally, when the second information is carried by the third TU code, the first extracting unit 51 is specifically configured to extract the third TU code from the code stream, where the first determining unit 52 is configured according to The third TU code determines the chroma component intra prediction mode.

Optionally, when the chrominance component mode information is carried by the fourth TU code, the first extracting unit 51 is specifically configured to extract the fourth TU code from the code stream, where the first determining unit The chrominance component intra prediction mode is determined according to the fourth TU code.

In the embodiment of the present invention, the method for group identification in the code stream by the chroma component intra prediction mode shortens the length of the codeword carrying the chroma component prediction mode information, thereby reducing the complexity of decoding on the mode information, and thereby removing The redundant information of the RM mode information and the cbf information of the luminance component improves the compression efficiency of the video image.

The technical solution provided by the embodiment of the present invention can be applied to the field of digital signal processing, and is implemented by a video encoder and a decoder. Video encoders, decoders are widely used in a variety of communication devices or electronic devices, such as: media gateways, mobile phones, wireless devices, personal data assistants (PDA, Personal Data Assistant), handheld or portable computers, GPS (Global Positioning) System, Global Positioning System) Receiver/Navigator, Camera, Video Player, Camcorder, VCR, Surveillance Equipment, etc. Such devices include processors, memory, and interfaces for transmitting data. The video codec can be implemented directly by a digital circuit or chip such as a DSP (Digital Signal Processor), or by software code to drive the processor to execute the flow in the software code.

Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the various examples described in connection with the embodiments disclosed herein can be implemented in a combination of electronic hardware or computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods for implementing the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present invention.

It will be apparent to those skilled in the art that, for the convenience of the description and the cleaning process, the specific operation of the system, the device and the unit described above may be referred to the corresponding processes in the foregoing method embodiments, and details are not described herein again.

In the several embodiments provided herein, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the device embodiments described above are merely illustrative For example, the division of the unit is only a logical function division, and the actual implementation may have another division manner, for example, multiple units or components may be combined or may be integrated into another system, or some features may be Ignore, or not execute. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in an electrical, mechanical or other form.

The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solution of the embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention, which is essential to the prior art or part of the technical solution, may be embodied in the form of a software product stored in a storage medium, including The instructions are used to cause a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and the like, which can store program codes. .

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the claims.

Claims

Rights request

A decoding method, comprising:

Extracting chroma component mode information in the code stream, the chroma component mode information being used to determine a chroma component intra prediction mode;

Determining a chroma component intra prediction mode according to the chroma component mode information;

When it is determined that the chroma component intra prediction mode is the DM mode, extracting residual prediction information in the code stream;

Performing a chroma component prediction operation according to the residual prediction information to obtain a chroma component intra frame prediction signal, where

The DM mode refers to a mode in which an intra prediction operation is performed on a chroma component using a prediction method specified by a luma component intra prediction mode, and

The luminance component intra prediction mode refers to a luminance component prediction mode determined based on luminance component mode information acquired from the code stream in the luminance component decoding process.

The method according to claim 1, wherein when the residual prediction information includes residual prediction flag information, the method further includes:

And extracting, from the code stream, a first fixed length code indicating the residual prediction flag information, where the residual prediction flag information is used to indicate whether the luminance component residual signal is used to assist the chrominance component for performing a prediction operation;

If the residual prediction flag information indicates that the luma component residual signal is used to perform the prediction operation, the residual prediction factor information is further extracted from the code stream, and the residual determined by the residual prediction factor information The prediction factor is used to specify how to use the luminance component residual signal to assist the chrominance component for prediction operations, where

The luminance component residual signal refers to a signal calculated to be generated during the decoding of the luminance component.

The method according to claim 1, wherein when the residual prediction information includes the residual prediction flag information, the method further includes:

Extracting, from the code stream, a first fixed length code indicating residual prediction flag information, where the residual prediction flag information is used to indicate whether to use a luminance component residual signal to assist a chrominance component for performing a prediction operation;

If the residual prediction flag information indicates that the luma component residual signal is used to perform the prediction operation using the luma component residual signal, when the residual prediction factor is the default value or is learned by the decoding end, the residual prediction factor is used to specify how Using a luminance component residual signal to assist the chrominance component for prediction operations, Medium

The method according to claim 2 or 3, wherein the performing a chroma component prediction operation according to the residual prediction information to obtain a chroma component intra prediction signal comprises:

Performing an intra prediction operation on the chroma component using a prediction method specified by the chroma component intra prediction mode to obtain a chroma component intra prediction signal;

Calculating a residual prediction correction signal according to the residual prediction factor and the luminance component residual signal;

The chrominance component intra prediction signal is corrected using the residual prediction correction signal to obtain a corrected chrominance component intra prediction signal.

The method according to claim 1, wherein the extracting the residual prediction information in the code stream comprises:

The luma component in the extracted code stream encodes the block flag cbf information, and determines that the cbf information indicates that the current block luma component includes a non-zero coefficient, and extracts residual prediction information in the code stream.

The method according to claim 1, wherein the chroma component mode information in the code stream is extracted, and the chroma component intra prediction mode is determined according to the chroma component mode information, and the method includes: extracting a code stream The first information included in the chroma component mode information is determined, and the chroma component intra prediction mode is determined according to the first information;

When the chroma component intra prediction mode cannot be determined according to the first information, determining the first default mode as the chroma component intra prediction mode, where

The first information includes information indicating whether the chroma component intra prediction mode is a DM mode or an LM class mode.

When the chrominance component intra prediction mode cannot be determined according to the first information, extracting second information included in the chrominance component mode information in the code stream, determining the chrominance component frame according to the second information Prediction mode, where

The first information includes information indicating whether the chroma component intra prediction mode is a DM mode or an LM class mode, The second information is used to indicate a remaining mode that is an intra prediction mode of the chroma component, where the remaining mode is a chroma component intra prediction mode other than a mode that may be determined by the first information. One, and

The LM class mode includes one or more modes for calculating a chrominance component predictor using a luminance component reconstruction value based on a correlation model.

8. The method according to claim 7, when the first information includes a second fixed length code, the first information in the extracted code stream, determining a chroma component intra prediction mode according to the first information , which is characterized by:

And extracting, by the code stream, the second fixed length code, and determining, according to the second fixed length code, whether the chrominance component intra prediction mode is a DM mode;

When the chroma component intra prediction mode does not include the LM class mode, if it is determined that the chroma component intra prediction mode is not the DM mode, it indicates that the chroma component cannot be determined according to the first information.

9. The method according to claim 8, when the first information further includes a third fixed length code, the first information in the extracted code stream, determining a chroma component intra prediction according to the first information The mode is characterized in that it further includes:

And if it is determined that the chroma component intra prediction mode is not the DM mode according to the extracted second fixed length code, further extracting the third fixed length code from the code stream, and according to the third fixed length Determining, by the code, whether the chroma component intra prediction mode is an LM class mode;

If it is determined that the chroma component intra prediction mode is an LM class mode, the chroma component intra prediction mode needs to be further determined; or

If it is determined that the chroma component intra prediction mode is not the LM class mode, it indicates that the chroma component intra prediction mode cannot be determined according to the first information.

10. The method according to claim 7, when the first information is carried by the first truncated one-element TU code, the first information in the extracted code stream is determined according to the first information, and the chrominance component frame is determined. The prediction mode is characterized by including:

Extracting, by the code stream, the first TU code, and determining, according to the first TU code, whether the chrominance component intra prediction mode is a DM mode or an LM class mode;

If it is determined that the chroma component intra prediction mode is neither a DM mode nor an LM class mode, Then, it is indicated that the chroma component intra prediction mode cannot be determined according to the first information.

The method according to claim 9 or 10, if it is determined that the chrominance component intra prediction mode is an LM class mode, the chrominance component intra prediction mode needs to be further determined, and the method includes:

When the LM class mode includes only the second default mode, it is determined that the chroma component intra prediction mode is the second default mode.

The LM class mode information is extracted from the code stream, and the chrominance component intra prediction mode is determined based on the LM class mode information.

13. The method according to claim 12, when the LM class mode includes two modes, a first LM class mode and a second LM class mode, extracting LM class mode information from a code stream, according to the LM Determining, by the class mode information, the chroma component intra prediction mode, comprising: extracting a fourth fixed length code indicating LM class mode information from the code stream, and determining the chroma according to the LM class mode information The component intra prediction mode is a first LM class mode or a second LM class mode.

14. The method according to claim 12, when the LM class mode includes three modes: a first LM class mode, a second LM class mode, and a third LM class mode, the extracting the LM class mode from the code stream And determining, according to the LM class mode information, the chrominance component intra prediction mode is one of the multiple modes, and the method includes:

The LM class mode information includes a fifth fixed length code and a sixth fixed length code.

And extracting, by the code stream, the fifth fixed length code in the LM class mode information, and determining, according to the fifth fixed length code, whether the chroma component intra prediction mode is a first LM class mode;

If it is determined that the chroma component intra prediction mode is not the first LM class mode, further extracting a sixth fixed length code in the LM class mode information from the code stream, and determining, according to the sixth fixed length code, The chrominance component intra prediction mode is the second LM class mode or the third LM class mode.

15. The method according to claim 12, when the LM class mode includes three modes: a first LM class mode, a second LM class mode, and a third LM class mode, the extracting the LM class mode from the code stream And determining, according to the LM-type mode information, the chrominance component intra prediction mode is one of the multiple modes, and the method further includes: The LM class mode information is carried by the second TU code,

Extracting, by the code stream, the second TU code, determining, according to the second TU code, whether the chroma component intra prediction mode is the first LM class mode, or the second LM class mode, or For the third LM class mode.

16. The method according to claim 7, when the second information is carried by a seventh fixed length FL code, when the chrominance component intra prediction mode cannot be determined according to the first information, the extraction The second information in the code stream is determined according to the second information, and the chrominance component intra prediction mode is determined, and the method includes:

Extracting the seventh fixed length FL code from the code stream, and determining the chroma component intra prediction mode according to the seventh fixed length FL code.

The method according to claim 7, when the second information is carried by the third TU code, when the chrominance component intra prediction mode cannot be determined according to the first information, extracting the code stream Determining the chrominance component intra prediction mode according to the second information, where the method includes:

Extracting the third TU code from the code stream, and determining the chrominance component intra prediction mode according to the third TU code.

18. The method according to claim 5, when the chrominance component mode information is carried by the fourth TU code, the chrominance component mode information in the extracted code stream is determined according to the chrominance component mode information. The component component intra prediction mode is characterized by comprising:

Extracting the fourth TU code from the code stream, and determining the chrominance component intra prediction mode according to the fourth TU code.

19. A decoding device, comprising:

a first extracting unit, configured to extract chroma component mode information in the code stream, where the chroma component mode information is used to determine a chroma component intra prediction mode;

a first determining unit, configured to determine a chroma component intra prediction mode according to the chroma component mode information extracted by the first extracting unit;

a second extracting unit, configured to: when the first determining unit determines that the chroma component intra prediction mode is a DM mode, extract residual prediction information in the code stream;

An operation unit, configured to perform a chroma component prediction operation according to the residual prediction information extracted by the second extraction unit to obtain a chroma component intra prediction signal, where

The DM mode refers to a chromaticity score determined by using a prediction method specified by a luminance component intra prediction mode The mode in which the intra prediction operation is performed, and

20. The apparatus according to claim 19, wherein the second extracting unit comprises an extracting module and a determining module:

When the residual prediction information includes residual prediction flag information, the extracting module is configured to extract, from the code stream, a first fixed length code indicating the residual prediction flag information, the residual prediction flag The information is used to indicate whether the luma component residual signal is used to perform the prediction operation using the luma component residual signal; the determining module is configured to determine that the residual prediction flag information indicates that the luma component residual signal is used to perform the prediction operation by using the luma component residual signal, The extraction module further extracts residual prediction factor information from the code stream, and the residual prediction factor determined by the residual prediction factor information is used to specify how to use the luminance component residual signal to assist the chrominance component for prediction operation, where

21. The apparatus according to claim 19, wherein the second extracting unit comprises an extracting module and a determining module:

When the residual prediction information includes residual prediction flag information, the extraction module is configured to extract, from the code stream, a first fixed length code indicating residual prediction flag information, where the residual prediction flag information is used. Determining whether to use the luma component residual signal to assist the chroma component for performing a prediction operation; the determining module is configured to: when the residual prediction flag information indicates that the luma component residual signal is used to perform a prediction operation, when the residual prediction is performed When the factor is the default value or is known by the decoding end, the residual prediction factor is used to specify how to use the luminance component residual signal to assist the chrominance component for prediction operation, where

22. The apparatus according to claim 20, wherein the operation unit comprises an operation module, a calculation module, and a correction module:

The operation module is configured to perform an intra prediction operation on the chroma component by using a prediction method specified by the chroma component intra prediction mode to obtain a chroma component intra prediction signal;

The calculation module is configured to calculate a residual prediction correction signal according to the residual prediction factor determined by the determining module and the luminance component residual signal acquired by the operation module;

The correction module is configured to correct the chroma component intra prediction signal by using the residual prediction correction signal acquired by the calculation module to obtain a modified chroma component intra prediction signal. number.

23. Apparatus according to claim 19 wherein:

The second extracting unit is specifically configured to: in the extracted code stream, the luma component encoding block flag cbf information, and determine that the cbf information indicates that the current block luma component includes a non-zero coefficient, and extract the residual prediction in the code stream. information.

24. Apparatus according to claim 19 wherein:

The first extracting unit is specifically configured to extract first information included in the chroma component mode information in the code stream, where the first determining unit determines a chroma component intra prediction mode according to the first information; When the determining unit cannot determine the chroma component intra prediction mode according to the first information, determining the first default mode as the chroma component intra prediction mode, where

25. Apparatus according to claim 19 wherein:

The first extracting unit is specifically configured to extract the first information included in the chroma component mode information in the code stream, where the first determining unit is specifically configured to determine a chroma component intra prediction mode according to the first information;

When the chrominance component intra prediction mode cannot be determined according to the first information, the first extracting unit further extracts second information included in the chrominance component mode information in the code stream, where the first determining unit is configured according to The second information determines the chroma component intra prediction mode, where

The first information includes information indicating whether the chroma component intra prediction mode is a DM mode or an LM class mode,

The second information is used to indicate a remaining mode that is an intra prediction mode of the chroma component, where the remaining mode is a chroma component intra prediction mode other than a mode that may be determined by the first information. One, and

26. Apparatus according to claim 25 wherein:

When the first information includes the second fixed length code, the first extracting unit is specifically configured to extract the second fixed length code from the code stream, where the first determining unit is specifically configured to be used according to the Determining, by the second fixed length code, whether the chroma component intra prediction mode is a DM mode;

When the chroma component intra prediction mode does not include the LM class mode, if the first determining unit is Determining that the chroma component intra prediction mode is not the DM mode indicates that the chroma component intra prediction mode cannot be determined according to the first information. .

27. Apparatus according to claim 26 wherein:

When the first information further includes a third fixed length code, if the first determining unit determines, according to the second fixed length code extracted by the first extracting unit, the chroma component intra prediction mode is not DM a mode, the first extracting unit further extracts the third fixed length code from the code stream, and the first determining unit determines, according to the third fixed length code, whether the chroma component intra prediction mode is For the LM class mode;

If the first determining unit determines that the chroma component intra prediction mode is an LM class mode, it is required to further determine the chroma component intra prediction mode; or

And if the first determining unit determines that the chroma component intra prediction mode is not the LM class mode, indicating that the chroma component intra prediction mode cannot be determined according to the first information.

28. Apparatus according to claim 25 wherein:

When the first information is carried by the first truncated one-dimensional TU code, the first extracting unit is specifically configured to extract the first TU code from the code stream, and the first determining unit is configured according to the first Determining, by the TU code, whether the chroma component intra prediction mode is a DM mode or an LM class mode;

And if the first determining unit determines that the chroma component intra prediction mode is neither a DM mode nor an LM class mode, indicating that the chroma component intra prediction mode cannot be determined according to the first information.

29. Apparatus according to claim 27 or claim 28 wherein:

The first determining unit is specifically configured to: when the LM class mode includes only the second default mode, determine that the chroma component intra prediction mode is the second default mode.

30. Apparatus according to claim 27 or claim 28 wherein:

If the first determining unit determines that the chroma component intra prediction mode is an LM class mode, the chroma component intra prediction mode needs to be further determined, and the first extracting unit further extracts the LM class mode from the code stream. Information, the first determining unit determines the chroma component intra prediction mode according to the LM class mode information.

31. Apparatus according to claim 30 wherein:

When the LM class mode includes two modes, a first LM class mode and a second LM class mode, The first extraction module is specifically configured to extract a fourth fixed length code indicating LM type mode information from the code stream, where the first determining unit determines the chrominance component intra prediction mode according to the LM type mode information. It is the first LM class mode or the second LM class mode.

32. Apparatus according to claim 30 wherein:

When the LM class mode includes three modes: a first LM class mode, a second LM class mode, and a third LM class mode, and the LM class mode information includes a fifth fixed length code and a sixth fixed length code, The first extracting unit is specifically configured to extract the fifth fixed length code in the LM type mode information from a code stream, where the first determining unit determines the chrominance component frame according to the fifth fixed length code Whether the intra prediction mode is the first LM class mode;

If the first determining unit determines that the chroma component intra prediction mode is not the first LM class mode, the first extracting unit further extracts a sixth fixed length code in the LM class mode information from the code stream. The first determining unit determines, according to the sixth fixed length code, that the chroma component intra prediction mode is a second LM class mode or a third LM class mode.

33. Apparatus according to claim 30 wherein:

When the LM class mode includes three modes: a first LM class mode, a second LM class mode, and a third LM class mode, and the LM class mode information is carried by the second TU code,

The first extracting unit extracts the second TU code from the code stream, and the first determining unit determines, according to the second TU code, whether the chroma component intra prediction mode is the first LM class mode. , or the second LM class mode, or the third LM class mode.

34. Apparatus according to claim 25 wherein:

When the second information is carried by the seventh fixed length FL code, the first extracting unit specifically extracts the seventh fixed length FL code from the code stream, and the first determining unit is configured according to the The seventh fixed length FL code determines the chrominance component intra prediction mode.

35. Apparatus according to claim 25 wherein:

When the second information is carried by the third TU code, the first extracting unit is specifically configured to extract the third TU code from the code stream, where the first determining unit is configured according to the third TU code. The chroma component intra prediction mode is determined.

36. Apparatus according to claim 23 wherein:

When the chrominance component mode information is carried by the fourth TU code, the first extracting unit is specifically configured to extract the fourth TU code from the code stream, where the first determining unit is according to the fourth The TU code determines the chroma component intra prediction mode.