WO2010111841A1

WO2010111841A1 - Predicting method and apparatus for frequency domain pulse decoding and decoder

Info

Publication number: WO2010111841A1
Application number: PCT/CN2009/071161
Authority: WO
Inventors: 苗磊; 刘泽新; 齐峰岩; 胡晨; 陈龙吟; 郎玥; 吴文海; 塔迪·哈维·米希尔; 张清
Original assignee: 华为技术有限公司
Priority date: 2009-04-03
Filing date: 2009-04-03
Publication date: 2010-10-07
Also published as: CN102246229A; CN102246229B

Abstract

A predicting method and apparatus for frequency domain pulse decoding and a decoder are provided. The method includes: dividing current frame and previous frame into spectral blocks according to spectral coefficient of the previous frame (11), judging whether the prediction between frames for the spectral block divided in the current frame is needed according to the correlation between the spectral blocks divided in the current frame and previous frame (12), for the spectral block of the current frame which is judged that the prediction between frames is needed, predicting the spectral coefficient which is not decoded of the spectral block of the current frame by using the decoded spectral coefficient in the spectral block corresponding to the previous frame and the decoded spectral coefficient in the current frame (13)..

Description

Prediction method and prediction device and decoder for frequency domain pulse decoding

The present invention relates to the field of audio codec technology, and in particular to a prediction method and prediction apparatus and decoder for frequency domain pulse decoding. Background technique

In the current frequency domain pulse decoding, when the number of bits is insufficient, generally according to the magnitude of the spectrum energy, or according to the auditory characteristics, some relatively important spectral coefficients are selected for encoding. For un-encoded spectral coefficients, when the decoder recovers, it is usually padded with 0s.

Since the relative energy magnitude or auditory characteristics of the intra-frame frequencies are different between frames, at the same bit rate, the continuous multi-frame does not guarantee that the spectral coefficients of the same frequency band are encoded. In this way, in the spectrum coefficients recovered by the decoding end, some frames in the same frequency band can decode the spectral coefficients, and some frames can only be obtained by filling 0, thus causing discontinuity of the spectral coefficients in the same frequency band, thereby causing insufficient auditory quality. Ideal, especially for signals with strong harmonics.

In the prior art, according to the similarity of spectral coefficients of different frequency bands in the frequency domain, intra-frame prediction is performed by using a small number of bits or no bits, so that the undecoded spectral coefficients are predicted by spectral coefficients of other frequency bands or frequency points. For example, the bandwidth extension (BWE, Bandwidth Extension) algorithm is used at present, and the spectral coefficient of the high frequency band is predicted by using the low frequency spectral coefficient according to the correlation between the high and low frequencies, so as to increase the bandwidth of the output signal, thereby improving the output signal. Hearing quality.

In the process of implementing the present invention, the inventors have found that: the spectral energy predicted in the frame tends to be biased in some frequency bands, especially when the low frequency harmonics are strong and the high frequency harmonics are also strong. The peak position often has a large deviation from the true peak position, which causes the audio signal to introduce more noise, which affects the auditory quality of the audio signal. Summary of the invention

In view of this, the embodiments of the present invention provide a prediction method, a prediction apparatus, and a decoder for frequency domain pulse decoding, which can better improve the auditory quality of an audio output signal. The method for predicting frequency domain pulse decoding provided by the embodiment of the present invention includes the following steps: performing spectrum block division on a current frame and a previous frame according to a spectral coefficient of a previous frame;

Determining, according to the correlation between the current frame and the spectrum block divided by the previous frame, whether the spectrum block of the current frame division needs to perform inter prediction;

For determining the current frame spectrum block that needs to be inter-predicted, using the decoded spectral coefficients in the corresponding spectrum block of the previous frame and the decoded spectral coefficients of the current frame, predicting the undecoded spectrum in the current frame spectrum block. coefficient.

The apparatus for predicting frequency domain pulse decoding provided by the embodiment of the present invention includes:

a block dividing unit, configured to perform frequency bin partitioning on the current frame and the previous frame according to the frequency coefficient of the previous frame;

a determining unit, configured to determine, according to the correlation between the current frame and the previous frame spectrum block that are divided by the block dividing unit, whether the spectrum block of the current frame division needs to perform inter prediction;

a prediction unit, configured to determine, by the determining unit, a current frame spectrum block that needs to be inter-predicted, and use the decoded spectral coefficient in the corresponding spectrum block of the previous frame and the decoded spectral coefficient of the current frame to predict the current Undecoded spectral coefficients in the frame spectrum block.

The decoder provided by the embodiment of the present invention includes the above-mentioned frequency domain pulse decoding prediction apparatus and converter, and the frequency domain pulse decoding prediction apparatus is configured to determine a current frame spectrum block that needs to be inter-predicted. Precoding the undecoded spectral coefficients in the current frame spectrum block by the decoded spectral coefficients in the previous frame corresponding to the spectral block and the decoded spectral coefficients of the current frame; the converter is configured to decode according to the frequency domain pulse The predicted frame spectral coefficients of the prediction device are subjected to frequency domain to time domain transformation, and output time domain audio signals.

According to the foregoing technical solution provided by the embodiment of the present invention, the current frame and the previous frame are first frequency-band partitioned according to the spectral coefficient of the previous frame, and then the current frame is determined according to the correlation between the current frame and the frequency block divided by the previous frame. Whether the divided spectrum blocks need to be inter-predicted, and finally determine the current frame spectrum block that needs to be inter-predicted, use the decoded spectral coefficients in the corresponding spectrum block of the previous frame and the decoded spectral coefficients of the current frame, and predict Undecoded spectrum system in the current frame spectrum block Number. Compared with the intra-prediction method of the prior art, for the signal of strong harmonicity, the spectrum of the current frame is smoother, the discontinuity phenomenon is reduced, and the sound spectrum is closer to the real spectrum, and the audio output is better improved. The signal is especially the auditory quality of the strong harmonic output signal. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in FIG. Other drawings can also be obtained from these drawings on the premise of sex.

1 is a flowchart of a method for predicting frequency domain pulse decoding according to Embodiment 1 of the present invention; FIG. 2 is a flowchart of a method for predicting frequency domain pulse decoding according to Embodiment 2 of the present invention; An example diagram of frequency information of a current frame and a previous frame is provided by the example; FIG. 4 is a block diagram of an algorithm structure according to Embodiment 2 of the present invention;

FIG. 5 is a structural block diagram of another algorithm according to Embodiment 2 of the present invention; FIG.

6 is a structural block diagram of an algorithm according to Embodiment 3 of the present invention;

FIG. 7 is a schematic structural diagram of a prediction apparatus for frequency domain pulse decoding according to Embodiment 4 of the present invention; FIG. 8 is a block diagram of a decoder according to Embodiment 5 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 only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Embodiment 1

Referring to FIG. 1, a method for predicting frequency domain pulse decoding according to an embodiment of the present invention includes the following steps: Step 11: Perform spectrum block division on a current frame and a previous frame according to a spectral coefficient of a previous frame; Step 12, according to a current frame and before Correlation of the spectral block of the frame division, judging the current frame division Whether the spectrum block needs to do inter prediction;

Step 13: predicting the current frame spectrum block that needs to be inter-predicted, using the decoded spectral coefficients in the corresponding spectrum block of the previous frame and the decoded spectral coefficients of the current frame, and predicting the undecoded in the current frame spectrum block. Spectral coefficient.

After the prediction of each spectrum block that needs inter prediction in the current frame is completed, the predicted current frame may be output, and then the subsequent decoding process may be further performed on the current frame, and finally the audio signal is output.

The method for predicting frequency domain pulse decoding provided by the embodiment of the present invention first performs frequency bin partitioning on the current frame and the previous frame according to the spectral coefficient of the previous frame, and then determines the current according to the correlation between the current frame and the spectrum block divided by the previous frame. Whether the spectrum block of the frame division needs inter-frame prediction, and finally, the current frame spectrum block that needs to be inter-predicted is used, and the spectrum coefficient decoded in the corresponding spectrum block of the previous frame and the decoded spectrum coefficient of the current frame are used. The undecoded spectral coefficients in the current frame spectrum block are predicted. Compared with the intra-prediction method of the prior art, for the signal of strong harmonicity, the frequency of the current frame is smoother, the discontinuity phenomenon is reduced, and the sound spectrum is closer, which improves the audio output better. The signal is especially the auditory quality of the strong harmonic output signal.

Embodiment 2

Referring to FIG. 2, a method for predicting frequency domain pulse decoding according to an embodiment of the present invention includes the following steps: Step 21: Corresponding to a frequency point of a spectrum coefficient decoded by a previous frame, centering the frequency point in a current frame and a previous frame A spectrum block is divided in the range of N frequency points before and after; wherein N > 1.

The frequency block is composed of frequency coefficients corresponding to consecutive L frequency points, and is centered on each frequency point corresponding to the spectrum coefficient decoded by the previous frame, and a spectrum block is divided in the range of N frequency points before and after. The number of spectral blocks divided by the current frame is equal to the number of spectral coefficients decoded by the previous frame, where L is the length of the spectral block, indicating the number of spectra in each spectral block, L = 2N + 1. Referring to FIG. 3, it is assumed that the number of total frequency points in the frequency band to be processed per frame is 64. At the decoding end, the current frame decodes four non-zero frequency coefficients, and the corresponding frequency points are 4, 15, and 40, respectively. And 50 (as shown by the vertical line); the previous frame of the current frame also decodes four non-zero frequency coefficients, corresponding to the frequency points of 3, 27, 40 and 50 (as shown by the vertical line). If N=2, that is, the number of spectrums in each spectrum block is L=5, corresponding to the frequency points of the four non-zero frequency coefficients decoded in the previous frame, the current frame and the previous frame are respectively divided into four. The frequency blocks to be processed (as indicated by the dashed box). Corresponding to FIG. 3, the number of spectral blocks divided by the current frame and the previous frame is equal to the number 4 of spectral coefficients decoded by the previous frame.

It should be noted that if the previous frame decodes two or more spectral coefficients in the range of adjacent N frequency points, the current frame is centered on any frequency point where the two or more spectral coefficients are located, before and after The range of each of the N frequency points is divided into only one frequency block. Suppose, the previous frame decodes non-zero spectral coefficients at the 3rd and 4th frequency points. If N=2, the current frame and the previous frame corresponding to the 3rd and 4th points of the previous frame are only divided into one frequency. Block, this frequency block can be centered on the 3rd or 4th frequency. At this time, there is no area overlap between each of the divided spectrum blocks, and the number of spectrum coefficients decoded by the previous frame is larger than the number of spectrum blocks divided by the current frame and the previous frame.

Step 22: Determine whether the distance between the frequency points corresponding to all the decoded spectral coefficients of the current frame and the previous frame is less than or equal to N. If the value is greater than or equal to M, determine that the current frame needs to perform inter prediction, otherwise it is not required; Where M is a preset value.

It should be noted that the value of M is determined according to the number of decoded spectral coefficients, and the more the decoded spectral coefficients are, the larger the value of M is.

Still referring to Figure 3, taking N=2, M=3, there are 3 positions (3/4, 40/40, 50/50) with the difference between the current frame and the previous frame being less than or equal to N, and greater than or equal to M, then Judging the current frame requires inter prediction. Since the division of the spectrum block is performed in step 21, in step 22, it is also possible to determine whether the current frame needs to be inter-predicted by: if each spectrum block in the current frame has a spectrum of the decoded spectral coefficient. If the number of blocks is greater than or equal to the preset value M, it is determined that the current frame requires ^1 inter prediction; otherwise, the current frame does not require ^1 inter prediction.

There are two points to be explained: First, the processing of the current frame does not necessarily refer to the previous frame, but also refers to the information of the previous frames. Second, when there is a frame loss phenomenon in the previous frame, the spectrum coefficient of the previous frame can be completely set to 0, so that the first frame after the frame loss can be prevented from inter-frame prediction, thereby avoiding bad influence; Keep the spectrum coefficient of the previous frame unchanged when the frame is lost, and whether to do it by the current frame. The condition of inter prediction (the number of positions where the frame of the previous frame and the frame is decoded before the frame loss is less than or equal to N is greater than or equal to M) to ensure the robustness of the algorithm and does not cause bad effects.

Step 23: Determine whether the divided spectrum blocks need to be inter-predicted one by one. If there is no decoded spectral coefficient in the spectrum block of the current frame, and there is a decoded spectral coefficient in the corresponding spectrum block of the previous frame, the current frame is determined. The spectrum block needs to be inter-predicted.

Still referring to FIG. 3, in the frequency point corresponding to the four non-zero spectral coefficients decoded in the previous frame, among the four to-be-processed frequency blocks divided by the current frame and the previous frame, only the frequency corresponding to the frequency point 27 At the block, the previous frame decodes the spectral coefficients, and the spectral coefficients are not decoded in the corresponding position of the current frame (27 +/- 2 ), while the other frequency blocks (frequency points 4, 40, and 50 correspond to In the spectrum block, the current frame has corresponding spectral coefficients decoded. Therefore, corresponding to FIG. 3, it is determined that the spectrum block corresponding to the frequency point 27 needs to be inter-predicted.

Step 24: Perform, for the spectrum block that needs to perform inter prediction, the amplitude of the frequency point at which the spectral coefficient is decoded in the corresponding spectrum block of the previous frame, and the minimum amplitude of all the spectral coefficients that have been decoded in the current frame. Weighted summation, the result of the weighted summation is taken as the amplitude of the corresponding frequency point of the undecoded spectral coefficient in the current frame spectrum block, and the sign of the spectral coefficient is the same as the sign of the spectral coefficient of the corresponding frequency point of the previous frame, where 0≤ ≤ 1.

The specific method for inter-prediction of the current spectrum block is as shown in equation (1):

Cur spec = * pre spec + β ^ {δ ^ cur spec _min ); a -\- β = \, 0 < S < \ ( 1 ) where cur- spec _mm indicates that all the spectral coefficients of the current frame have been decoded The minimum amplitude, pre _ spec, represents the amplitude of the frequency at which the frequency coefficient decoded in the previous frame corresponds to the frequency block.

Is a weighting coefficient, which can be selected according to actual conditions. For a strong harmonic signal, preferably,

« = = 0.5, = 0.8.

Still referring to FIG. 3, the spectral coefficient prediction for the frequency point 27 is a weighted sum of the amplitude of the spectral coefficient at the 27-bit point of the previous frame and the minimum amplitude of 0.8 times of all the spectral coefficients decoded by the current frame. The amplitude of the spectral coefficients at the current frame rate point 27 is the same as the sign at the 27th point of the previous frame. For example, the amplitude of the 27-point frequency of the previous frame is 30, and the amplitude of the four frequency points of the current frame is 25, 15, 20, 21, « = ^ = 0.5, ^ = 0.8, the amplitude of the current frame 27 is predicted by equation (1) to be 21, and the sign is positive, which is consistent with the symbol at the 27th point of the previous frame.

It should be noted that, in the embodiment of the present invention, when determining whether the current spectrum block needs to be processed, it is determined based on the spectrum block, instead of being determined based on the frequency point. It is possible that some frequency points in the previous frame decode the spectral coefficients, and the spectrum coefficients are not decoded at the same frequency point of the current frame, but the spectral coefficients are decoded at a position where the distance is small, and no corresponding processing is performed at this time, as shown in the figure. In the third frame, the previous frame frequency point 3 decodes the spectral coefficient, and the current frame frequency point 3 does not decode the spectral coefficient, but the current frame frequency point 4 decodes the spectral coefficient, and at this time, the frequency of the current frame is not Need to do inter-frame prediction processing.

It should also be noted that if more than two frequency coefficients are decoded in the same spectrum block of the previous frame, and no spectral coefficients are decoded in the corresponding spectrum block in the current frame, the corresponding spectrum blocks are decoded in the same spectrum block. For each frequency point where two or more spectral coefficients are located, the current frame is separately subjected to spectrum prediction.

Step 25: Output the spectral coefficient of the current frame after the prediction processing, and save the frequency coefficient of the current frame before the prediction processing as the frame information of the previous frame of the next frame.

After the above step 24, the current frame predicts the spectral coefficient at the frequency point 27. At this time, the current frame has five non-zero frequency coefficients, and the corresponding frequency points are 4, 15, 27, 40, and 50, respectively. The spectral coefficients of the current frame are output, and the spectral coefficients of the current frame before the prediction processing (the corresponding frequency points are 4, 15, 40, and 50, respectively) are saved as the frame information of the previous frame of the next frame.

So far, the entire processing flow of the current frame prediction of the frequency domain pulse decoding is completed.

The block diagram of the algorithm structure of the embodiment of the present invention is as shown in FIG. 4. First, according to the frequency coefficient decoded by the current frame and the previous frame, the number of spectrum blocks to be processed is first determined, and k represents the ordinal number of the spectrum block, and the initialization starts from 0. Corresponding to the frame information shown in FIG. 3, the number of spectrum blocks to be processed is equal to the number 4 of spectral coefficients decoded in the previous frame. Then, it is judged whether the number of positions in the corresponding block in which the current frame and the previous frame are decoded out of the spectral coefficients is less than or equal to N. If the condition is met, the interframe prediction is performed on the current frame, and the spectrum before the current frame prediction is saved. The coefficient is used as the previous frame information of the next frame; otherwise, the current frame is not processed, but only the spectrum coefficient before the current frame prediction is saved as the next frame. Frame information.

Corresponding to Fig. 3, N=2 and M=3 are preferable. The spectral coefficients are decoded at the previous frame frequency point 27, and the spectral coefficients are not decoded within the spectrum block (27 +/- N) of the current frame division; meanwhile, the difference between the current frame and the corresponding position of the previous frame is less than or equal to N. 3 (3/4, 40/40, 50/50), greater than or equal to Μ=3, at this time, the amplitude of the spectral coefficient of the previous frame frequency point 27 and the amplitude of all the decoded spectral coefficients of the current frame are the smallest. The weighted sum result is taken as the amplitude of the spectral coefficient of the current frame frequency point 27, and the symbol is consistent with the sign of the previous frame frequency point 27.

It should be noted that when most frames can satisfy the inter prediction processing condition, when judging whether the current frame is inter-predicted, it may be determined after all the spectrum blocks are processed, instead of being between the spectrum block frames. Judging before the prediction process, this saves the average complexity of the algorithm.

As shown in FIG. 5, this embodiment can also use another algorithm structure block diagram to determine whether the current frame is inter-predicted after all the spectrum blocks are processed. The specific processing algorithm is as follows:

First, the number of positions where the positional interval between the current frame and the previous frame decoded spectral coefficients is less than or equal to N, i=0, and the ordinal number k=0 of the spectrum block to be processed are initialized, and the maximum number of spectrum blocks to be processed is determined. Regardless of whether the current frame satisfies the condition for inter prediction, the current frame is temporarily passed through the algorithm of the present invention: For each spectrum block to be processed, if the spectral coefficient block of the previous frame is decoded, the corresponding block of the current frame is decoded. The spectral coefficients are not decoded. The spectrum block in which the frequency point 27 in FIG. 3 is located satisfies this condition, so that the amplitude of the spectral coefficients of the previous frame frequency point 27 and the smallest of all decoded spectral coefficients of the current frame can be obtained. The weighted sum of the amplitude = 0.8 times, the amplitude of the spectral coefficient of the current frame frequency point 27, the symbol and the symbol of the previous frame frequency point 27 are consistent; if the current frame spectrum block and the previous frame corresponding to the spectrum block have spectral coefficients Decode out to determine whether the current frame position and the previous frame position in the spectrum block are less than or equal to N=2. If yes, i is incremented by one, otherwise i is unchanged until all spectrum blocks are processed. After all the spectrum blocks are processed, it is judged whether i is greater than or equal to M. If yes, the current frame satisfies the processing condition, the current frame spectral coefficient after the prediction processing is output, and the current frame spectral coefficient before the prediction processing is saved as the next frame. The previous frame spectral coefficient; otherwise, the current frame does not satisfy the processing condition, the current frame spectral coefficient is restored to the spectral coefficient before the prediction processing, and the current frame is saved. The frequency coefficient before the processing is used as the previous frame frequency coefficient of the next frame.

Embodiment 3

The embodiment of the present invention provides another method for inter-frame prediction of frequency domain pulse decoding. The difference between this embodiment and the second embodiment is that, in this embodiment, whether the current frame is inter-predicted is based on the current frame and before. The frame is determined according to the correlation of the energy of the decoded spectral coefficients in the spectrum block, and the second embodiment is that the positional spacing of the spectral coefficients decoded according to the current frame and the previous frame is less than or equal to N (ie, the spectral coefficient The relevance of the location) to judge.

Specifically, in determining whether the current frame needs to perform inter prediction, the embodiment is determined according to energy information corresponding to all decoded spectral coefficients in each spectrum block of the current frame and the previous frame, if the energy is equivalent If the number of spectrum blocks is greater than or equal to a preset value, it is determined that the current frame needs to be inter-predicted. The spectral block energy can be expressed by the sum of the squares of the amplitudes of the spectral coefficients in the spectral block or the root mean square of the squared sum or the amplitude of the spectral coefficients. A formula for calculating the energy of the spectral block based on the sum of the squares of the amplitudes of the spectral coefficients is:

1-1

Ener[k] = ^spec[k + ] * spec[k + ] ( 2 ) where k is the ordinal number of the spectrum block and L is the number of spectral coefficients in the spectrum block.

The so-called energy is equivalent, that is, the energy ratio between the previous frame and the current frame spectrum block is in the range of [1/E, E], for example, E can take 0.8, and generally the value of E can be closer to 1 to ensure prediction. accuracy.

In this embodiment, a flow chart of the algorithm structure similar to FIG. 4 or FIG. 5 can be used to determine whether the current frame is inter-predicted. When most frames can satisfy the inter prediction processing conditions, when judging whether the current frame is inter-predicted, it can be judged after all the spectrum blocks are processed, so as to save the average complexity of the algorithm. Referring to Figure 6, the specific processing algorithm is as follows:

First, the current frame and the previous frame are decoded to decode the energy of the spectral coefficients in the spectrum block by the number i=0 and the ordinal number k=0 of the spectral coefficient block to be processed, and the maximum number of spectrum blocks to be processed is determined. Then, the current frame is temporarily passed through the algorithm of the present invention regardless of whether the current frame satisfies the condition of the inter prediction algorithm: For each spectrum block, if the previous frame decodes the spectral coefficient block, and the current frame is not decoded, As shown in the spectrum block where the frequency point 27 is located in FIG. 3, the weighted sum of the spectral coefficients of the previous frame frequency point 27 and the minimum amplitude of all the decoded spectral coefficients of the current frame = 0.8 times as the current frame frequency point. The amplitude of the spectral coefficient of 27 is consistent with the sign of the previous frame frequency point 27; if both the current frame spectral block and the previous frame spectral block have spectral coefficients decoded, it is determined that the current frame and the previous frame in the spectral block are decoded. Whether the energy of the spectral coefficients is equal, if it is, i is increased by one, otherwise i remains unchanged until all spectrum blocks are processed. After all the spectrum blocks have been processed, it is judged whether i is greater than or equal to M, and M is a preset value. If yes, the current frame satisfies the processing condition, outputting the current frame frequency coefficient after the prediction processing, and saving the current frame frequency coefficient before the prediction processing as the previous frame spectral coefficient of the next frame; otherwise, the current frame does not satisfy the processing condition, The current frame spectral coefficient is restored to the current frame spectral coefficient before the prediction process for output, and the current frame spectral coefficient before the prediction process is saved as the previous frame spectral coefficient of the next frame.

It should be noted that the number L of spectrums in the spectrum block divided in this embodiment is preferably smaller than the number L of spectrums in the spectrum block in the second embodiment, because when the energy equivalent is counted, when the spectrum block is larger At the same time, even if the energy of the spectral coefficients in the spectrum block is equal between two consecutive frames, it is possible that the correlation between two consecutive frames is low. Therefore, if the length of the spectrum block in the second embodiment is L = 5, the length L of the spectrum block in the embodiment is preferably less than or equal to 3, that is, L 3 .

It can be understood that, when determining whether the current frame needs to perform inter prediction according to the inter-frame correlation, the determination of the correlation of the energy of the spectral coefficients in the spectrum block based on the current frame and the previous frame may also be determined based on the current frame. The determination of the number of spectral blocks in which the spectral coefficients are decoded is combined with a determination as to whether or not the current frame is inter-predicted. For a specific method of inter-frame prediction, refer to the description of the above embodiments of the invention, and details are not described herein again.

The foregoing method embodiment of the present invention firstly performs frequency bin partitioning on the current frame and the previous frame according to the spectral coefficient of the previous frame, and determines whether the current frame needs to perform inter prediction according to the current frame and the spectrum block divided by the previous frame. Then, it is determined whether the divided spectrum block needs to be inter-predicted for the current frame that needs to be inter-predicted. If there is no decoded spectral coefficient in the spectrum block of the current frame, the corresponding spectrum block of the previous frame is decoded. The spectral coefficient, then determine the spectrum block of the current frame, Finally, for the spectrum block that needs to be inter-predicted, the amplitude of the frequency point of the spectral coefficient decoded in the corresponding spectrum block of the previous frame, and the minimum amplitude of all the spectral coefficients that have been decoded by the current frame

(0≤^≤1) times performing weighted summation, and the result of the weighted summation is used as the amplitude of the corresponding frequency point of the undecoded spectral coefficient in the current frame spectrum block, and the symbol of the spectral coefficient corresponds to the previous frame The symbols of the frequency points are the same, wherein whether the current frame needs to be inter-predicted according to the inter-frame correlation can be judged according to the spacing information of the frequency points corresponding to all the decoded spectral coefficients of the current frame and the previous frame, and/or according to the current The energy information of the spectrum block corresponding to all the decoded spectral coefficients of the frame and the previous frame is judged. Compared with the intra-prediction method of the prior art, for the signal of strong harmonicity, the spectrum of the current frame is smoother, the discontinuity phenomenon is reduced, and the signal is closer to the real spectrum, and the audio output signal is better improved. Especially the auditory quality of strong harmonic audio output signals.

Embodiment 4

As shown in FIG. 7, corresponding to the foregoing method embodiment, a prediction apparatus for frequency domain pulse decoding provided by the embodiment of the present invention includes:

a block dividing unit 71, configured to perform frequency bin partitioning on the current frame and the previous frame according to the spectral coefficients of the previous frame;

The determining unit 70 is configured to determine, according to the current frame and the previous frame spectrum block that are divided by the block dividing unit 71, whether the spectrum block of the current frame division needs to perform inter prediction;

The prediction unit 74 is configured to determine, by the determining unit 70, a current frame spectrum block that needs to be inter-predicted, and use the decoded spectral coefficient in the corresponding spectrum block of the previous frame and the decoded spectral coefficient of the current frame. The undecoded spectral coefficients in the current frame spectrum block are predicted.

The block dividing unit 71 includes:

The first dividing module 711 is configured to: at a frequency point corresponding to the spectral coefficient decoded by the previous frame, and divide a frequency block in the range of the N frequency points in the current frame and the previous frame respectively. Where N ≥ l. At this time, the number of spectral blocks divided by the current frame is equal to the number of spectral coefficients decoded by the previous frame. and / or,

a second dividing module 712, configured to decode two if the previous frame is in the range of adjacent N frequency points For the above frequency coefficient, any frequency point is selected from the frequency points where the two or more spectral coefficients are located, and the selected frequency points are centered at the N frequency points in the current frame and the previous frame respectively. The range is divided into a frequency block, where N ≥ l. At this time, there is no area overlap between each of the divided spectrum blocks, and the number of spectral coefficients decoded by the previous frame is larger than the number of spectrum blocks divided by the current frame.

The determining unit 70 includes:

The frame determining sub-unit 72 is configured to determine, according to the current frame and the previous frame spectral block divided by the block dividing unit 71, whether the current frame needs to be inter-predicted;

The block judging sub-unit 73 is configured to determine, by the frame judging unit 72, the current frame that needs to be inter-predicted, and determine whether the spectrum block of the current frame division needs to perform inter-frame prediction.

The frame judging subunit 72 includes:

The position determining module 721 is configured to determine, according to the number of the spectrum blocks of the decoded spectral coefficients in the current frame, if the number of the spectral blocks of the decoded spectral coefficients in the current frame is greater than or equal to a preset value, The current frame needs to be inter-predicted; and/or,

The energy judging module 722 is configured to determine, according to the spectrum block of the spectral coefficient decoded in the current frame and the energy information of the corresponding spectrum block in the previous frame, if the number of corresponding spectrum block energy is greater than or equal to a preset value, Judging the current frame requires inter prediction.

The block determining sub-unit 73 may be specifically configured to determine, according to whether the current frame and the previous frame corresponding to the spectrum block have decoded spectral coefficients, if there is no decoded spectral coefficient in the spectrum block of the current frame, and the previous frame If there is a decoded spectral coefficient in the corresponding spectrum block, it is determined that the spectrum block of the current frame needs to be inter-predicted.

The prediction unit 74 may be specifically configured to: weight an amplitude of a frequency point of the spectral coefficient decoded in the corresponding spectrum block of the previous frame, and a δ times of a minimum amplitude of all the spectral coefficients that have been decoded in the current frame. Summing, the result of the weighted summation is used as the amplitude of the corresponding frequency point of the undecoded spectral coefficient in the current frame spectrum block, and the sign of the spectral coefficient is the same as the symbol of the corresponding frequency point of the previous frame, where 0≤ ≤ 1.

It is to be understood that the apparatus provided by the embodiment of the present invention may further include: The output saving unit 75 is configured to output the spectral coefficient of the current frame after the prediction processing, and save the frequency coefficient of the current frame before the prediction processing as the frame information of the previous frame of the next frame.

The apparatus for predicting frequency domain pulse decoding provided by the embodiment of the present invention first determines whether the current frame needs to be inter-predicted by the frame determining unit, and then determines the current frame that needs to be inter-predicted by the block determining unit. Whether the spectrum block needs to be inter-predicted for judgment, and finally, to determine the spectrum block that needs to be inter-predicted, the prediction unit uses the decoded spectrum coefficient in the corresponding spectrum block of the previous frame and the decoded spectrum coefficient of the current frame. , predicting undecoded spectral coefficients in the current frame spectrum block. Compared with the intra-prediction method of the prior art, for the signal of strong harmonicity, the spectrum of the current frame is smoother, the discontinuity phenomenon is reduced, and the signal is closer to the real spectrum, and the audio output signal is better improved. In particular, the auditory quality of a strong harmonic output signal.

Embodiment 5

As shown in FIG. 8, an embodiment of the present invention further provides a decoder, including a frequency domain pulse decoding predicting device 81 and a converter 82;

The frequency domain pulse decoding prediction apparatus 81 is configured to: determine a current frame spectrum block that needs to be inter-predicted, use a spectrum coefficient decoded in a corresponding spectrum block of the previous frame, and a decoded spectrum coefficient of the current frame, Predicting undecoded spectral coefficients in the current frame spectrum block;

The converter 82 is configured to perform frequency domain to time domain transform according to the predicted frame frequency spectrum coefficient of the frequency domain pulse decoded prediction apparatus 81, and output a time domain audio signal.

The prediction device 81 of the frequency domain pulse decoding can be more specifically referred to the prediction device of the frequency domain pulse decoding in the foregoing method embodiment and the device embodiment 4, and details are not described herein again.

A person skilled in the art will also appreciate that the elements and algorithm steps of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both, in order to clearly illustrate the inter The composition and steps of the examples have been generally described in terms of functions in the above description. 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 to implement the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present invention. The scope.

The steps of a method or algorithm described in connection with the embodiments disclosed herein can be implemented in hardware, a software module executed by a processor, or a combination of both. Software modules can be placed in random access memory

(RAM), memory, read only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

Claim

A method for predicting frequency domain pulse decoding, comprising:

Performing spectrum block division on the current frame and the previous frame according to the spectral coefficient of the previous frame;

Determining whether the spectrum block of the current frame division needs to be inter-predicted according to the correlation between the current frame and the spectrum block divided by the previous frame;

2. The method according to claim 1, wherein the step of performing spectrum block partitioning on the current frame and the previous frame according to the spectral coefficient of the previous frame comprises:

Corresponding to the frequency point where the spectral coefficient decoded by the previous frame is located, a spectrum block is divided in the range of the N frequency points in the current frame and the previous frame, respectively, with the frequency point as the center; and/or

If the previous frame decodes more than two spectral coefficients in the range of adjacent N frequency points, then any frequency point is selected from the frequency points where the two or more spectral coefficients are located, and respectively in the current frame and the previous frame. The selected frequency point is a spectrum block divided by the center of the N frequency points before and after;

Where N > 1.

The method according to claim 1 or 2, wherein, according to the correlation between the current frame and the spectrum block divided by the previous frame, the step of determining whether the spectrum block of the current frame division needs inter prediction includes:

Determining whether the current frame needs to be inter-frame predicted according to the correlation between the current frame and the spectrum block divided by the previous frame;

For determining the current frame that needs to be inter-predicted, it is judged one by one whether the spectrum block of the current frame division needs to be inter-predicted.

The method according to claim 3, wherein the step of determining whether the spectrum block of the current frame division needs to perform inter prediction according to the frequency block correlation of the current frame and the previous frame includes: If the number of the spectrum blocks of the decoded spectral coefficients in the current frame is greater than or equal to a preset value, it is determined that the current frame needs to be inter-predicted; and/or,

If the number of the spectral blocks of the decoded spectral coefficients in the current frame and the corresponding spectral blocks in the previous frame are greater than or equal to a preset value, it is determined that the current frame needs to be inter-predicted.

The method according to claim 3, wherein the step of determining whether the spectrum block of the current frame division needs to perform inter prediction comprises:

If there is no decoded spectral coefficient in the spectrum block of the current frame, and there is a decoded spectral coefficient in the corresponding spectral block of the previous frame, it is determined that the spectral block of the current frame needs to be inter-predicted.

The method according to claim 5, wherein the pair determines a current frame frequency block that needs to be inter-predicted, and uses a frequency coefficient that is decoded in the corresponding frequency block of the previous frame and The spectral coefficients of the current frame have been decoded, and the steps of predicting the undecoded spectral coefficients in the current frame spectrum block include:

And weighting the amplitude of the frequency point of the spectral coefficient decoded in the corresponding spectrum block of the previous frame and the minimum of the minimum amplitude of all the spectral coefficients decoded by the current frame, and using the result of the weighted summation as a The amplitude of the corresponding frequency point of the spectral coefficient is not decoded in the current frame spectrum block, and the symbol of the spectral coefficient is the same as the symbol of the corresponding frequency point of the previous frame, where 0≤ ≤1.

The method according to claim 1, wherein the method further comprises: outputting a spectral coefficient of the current frame after the prediction processing, and saving a spectral coefficient of the current frame before the prediction processing as a previous frame of the next frame. Frame information.

8. A prediction apparatus for frequency domain pulse decoding, comprising:

a block dividing unit, configured to perform frequency segmentation on the current frame and the previous frame according to the frequency coefficient of the previous frame;

a prediction unit, configured to determine, by the determining unit, a current frame spectrum block that needs to be inter-predicted, use a spectrum coefficient decoded in a corresponding spectrum block of the previous frame, and a spectrum system that is decoded by the current frame Number, predicts the undecoded spectral coefficients in the current frame spectrum block.

The device according to claim 8, wherein the block dividing unit comprises: a first dividing module, configured to correspond to a frequency point of a spectral coefficient decoded by a previous frame, in the current frame and the previous frame respectively The frequency point is divided into a frequency block in the range of N frequency points before and after the center, where N > 1 ; and/or,

a second dividing module, configured to select any frequency point from the frequency points where the two or more spectral coefficients are located, if the previous frame decodes two or more spectral coefficients in the range of adjacent N frequency points, at the current A spectrum block is divided into a range of N frequency points before and after the selected frequency point in the frame and the previous frame, where N > 1.

The device according to claim 8 or 9, wherein the determining unit comprises: a frame determining sub-unit, determining a current frame according to a correlation between a current frame and a previous frame spectrum block divided by the block dividing unit Whether to do inter prediction;

The block determining sub-unit is configured to determine, by the frame determining module, that the current frame that needs to be inter-predicted, and determine whether the spectrum block of the current frame division needs inter-frame prediction one by one.

The apparatus according to claim 10, wherein the frame determining subunit comprises: a position determining module, configured to determine, according to the number of spectrum blocks of the decoded spectral coefficients in the current frame, if the current frame If the number of the spectrum blocks of the decoded spectral coefficients is greater than or equal to a preset value, it is determined that the current frame needs to be inter-frame predicted; and/or,

The energy judging module is configured to determine, according to the spectrum block of the spectral coefficient decoded in the current frame and the energy information of the corresponding spectrum block in the previous frame, if the number of corresponding energy of the corresponding spectrum block is greater than or equal to a preset value, The current frame needs to be inter-predicted.

The apparatus according to claim 11, wherein the block determining unit is configured to: determine, according to whether the current frame and the corresponding spectrum block in the previous frame correspond to the decoded spectral coefficient, if the spectrum block of the current frame There is no decoded spectral coefficient, and there is a decoded spectral coefficient in the corresponding spectral block of the previous frame, then it is determined that the spectral block of the current frame needs to be inter-predicted.

The device according to claim 12, wherein the prediction unit is specifically configured to: And weighting the amplitude of the frequency point of the spectral coefficient decoded in the corresponding spectrum block of the previous frame and the minimum of the minimum amplitude of all the spectral coefficients decoded by the current frame, and using the result of the weighted summation as a The amplitude of the corresponding frequency point of the spectral coefficient is not decoded in the current frame spectrum block, and the symbol of the spectral coefficient is the same as the symbol of the corresponding frequency point of the previous frame, where 0≤ ≤1.

The device according to claim 8, wherein the device further comprises: an output saving unit, configured to output a spectral coefficient of the current frame after the prediction processing, and save the frequency coefficient of the current frame before the prediction processing The frame information of the previous frame as the next frame.

A decoder, comprising the frequency domain pulse decoding prediction apparatus and converter according to any one of claims 8 to 14,

The frequency domain pulse decoding prediction apparatus is configured to: determine a current frame spectrum block that needs to be inter-predicted, use a spectrum coefficient decoded in a corresponding spectrum block of the previous frame, and a decoded spectrum coefficient of the current frame, and predict Undecoded spectral coefficients in the current frame spectrum block;

The converter is configured to perform frequency domain to time domain transform according to the frame spectrum coefficient predicted by the prediction device of the frequency domain pulse decoding, and output a time domain audio signal.