CN106409302B - Audio-frequency water mark method and system based on insertion regional choice - Google Patents

Abstract

The invention provides an audio watermarking method and system based on embedding region selection. The embedding process includes reading an audio file, first judging whether each frame signal can be used as an embedding region, and then selecting an embedding frequency segment of the audio watermark; Discrete Fourier transform, generate a binary pseudo-random spread spectrum sequence, embed the watermark, and transform to the time domain; the detection process includes reading the audio file to be detected, judging whether each frame of signal can be used as an embedded area, and calculating the detection range The starting point and the end point of the frequency domain, the discrete Fourier transform is performed to generate a binary pseudo-random spread spectrum sequence, the sufficient statistics of the detection are calculated, and the detected watermark bits are obtained. The invention proposes to filter out the transient signal through the ratio of the maximum energy to the minimum energy in the frame to improve the accuracy of watermark detection, and to improve the robustness of the watermark by embedding the watermark in a frequency band that is perceived by human ears.

Description

Audio Watermarking Method and System Based on Embedding Region Selection

technical field

The present invention relates to the technical field of digital audio watermarking, in particular to an audio watermarking method and system based on embedded region selection.

Background technique

Digital audio watermarking is a signal processing operation that adds some digital information to the audio signal to achieve the purpose of document authenticity identification, copyright protection, and information hiding. The selection technology of audio watermark embedding area refers to selecting a suitable audio area to embed the watermark before the watermark is embedded in the audio signal. The traditional audio watermarking technology does not take into account the characteristics of the audio signal, and embeds the watermark on the entire audio file, which will lead to 1) After the watermark is embedded in the low-amplitude area of the audio signal, the amplitude exceeds the masking threshold and generates noise, which destroys the perception. Transparency; 2) For the transient signal with drastic changes in the audio signal, the variance of the audio signal in this area is large, and the watermark error rate when detecting the watermark is very high after embedding the watermark; 3) Embedding the watermark in the frequency domain, If the watermark is embedded in an area that is not noticeable to the human ear, after signal processing or lossy audio compression, part of the watermark will be lost, resulting in a high bit error rate for watermark detection.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an audio watermarking technology for embedding in a selected region, so that the watermark can be embedded in a suitable audio region, so as to avoid unnecessary noise and reduce the occurrence of bit errors.

In order to achieve the above purpose, the technical solution provided by the present invention provides an audio watermarking method based on embedding region selection, including an embedding process and a detection process,

The embedding process includes the following steps,

Step A1, read the audio file, obtain the sampling rate fs1 and the signal x _n of the time domain audio of the nth frame after framing, the frame length is N,

First, judge whether the signal x _n of each frame can be used as an embedded area.

Then, for each frame signal x _n that can be used as an embedded area, the selection of the embedded frequency segment of the audio watermark is performed, and the preset starting frequency of the embedding according to the frequency part that is sensitive to human ear perception is FWMIN, and the ending frequency is FWMAX. The start embedding point freqmin1 and the embedding end point freqmax1 are calculated as follows,

freqmin1=floor((FWMIN×2.0/fs1)×N)

freqmax1=floor((FWMAX×2.0/fs1)×N)

Among them, floor is the round-down function;

Step A2, perform discrete Fourier transform on each frame signal x _n capable of embedding the watermark to obtain the frequency domain signal X _n ;

Step A3, using the key key as a random number seed, generating a binary pseudo-random spread spectrum sequence u with a length of freqmax1-freqmin1+1;

Step A4, according to the spread spectrum sequence u, the frequency domain signal X _n and the watermark bit b, the watermark is embedded to obtain the frequency domain signal after embedding the watermark, and the calculation is as follows:

|X′ _n |=|X _n |+bαu

Among them, α is a constant, which controls the embedding strength of the watermark, and |X _n | and |X′ _n | represent the frequency domain amplitude before and after embedding the watermark, respectively. frequency domain signal

Among them, ∠X _n represents the phase of the frequency domain signal, X′ _n represents the frequency domain signal after embedding the watermark, and e is the mathematical natural exponent;

Step A5, transform the frequency domain signal X' _n after embedding the watermark to the time domain, and generate the audio file embedded in the watermark;

The detection process includes the following steps:

Step B1, read the audio file to be detected, and obtain the nth frame signal z _n and the sampling rate fs2 after the time domain is divided into frames,

First, judge whether each frame of signal x _n can be used as an embedded area;

For each frame signal x _n that can be used as the embedded area, as the signal to be detected, calculate the starting point freqmin2 of the detection range and the end point freqmax2 of the frequency domain

freqmin2=floor((FWMIN×2.0/fs2)×N)

freqmax2=floor((FWMAX×2.0/fs2)×N)

Step B2, perform discrete Fourier transform to obtain the frequency domain signal Z _n of the signal to be detected, and the corresponding frequency domain amplitude value is denoted as |Z _n |;

Step B3, use the key key as the random number seed to generate a binary pseudo-random spread spectrum sequence u with a length of freqmax2-freqmin2+1;

Step B4, according to the spread spectrum sequence u and the frequency domain amplitude value |Z _n | of the signal to be detected, the sufficient statistic r _n for detection is calculated as follows:

If the sufficient statistic rn _≥ 0, the detected watermark bit is b=1; otherwise, the detected watermark bit is b=0.

Moreover, in step A1 and step B1, it is determined whether the signal x _n of each frame can be used as an embedded area, and the implementation is as follows:

1) Average energy of signal x _n The size of τ exceeds the preset corresponding threshold τ ₁ , if it is, it is a silent zone, and watermarking is not allowed;

2) If the signal x _n contains a transient signal, it is not allowed to embed the watermark.

Moreover, whether a transient signal is included in the signal x _n is determined by the following method:

Suppose a frame of signal is decomposed into S blocks, and the energy of the S blocks is calculated respectively, and the energy ratio rate of the block with the maximum energy and the minimum energy block is compared with the preset corresponding threshold τ ₂ , if the rate is greater than τ ₂ , it is considered that the The frame signal contains transient signals.

The present invention also correspondingly provides an audio watermarking system based on embedding region selection, comprising an audio watermark embedding subsystem and a watermark detection subsystem,

The audio watermark embedding subsystem includes the following modules,

Select the appropriate region embedding module to read the audio file to obtain the sampling rate fs1 and the time domain audio signal x _n of the nth frame after framing, and the frame length is N,

First, judge whether the signal x _n of each frame can be used as an embedded area.

Then, for each frame signal x _n that can be used as an embedded area, the selection of the embedded frequency segment of the audio watermark is performed, and the selection of the embedded frequency segment of the audio watermark is performed, and the preset start frequency of embedding according to the frequency part that is sensitive to human ear perception is set as FWMIN, the end frequency is FWMAX, the start embedding point freqmin1 and embedding end point freqmax1 of a frame are calculated as follows,

freqmin1=floor((FWMIN×2.0/fs1)×N)

freqmax1=floor((FWMAX×2.0/fs1)×N)

Among them, floor is the round-down function;

The first time-frequency conversion module is used to perform discrete Fourier transform on each frame signal x _n that can be embedded in the watermark to obtain the frequency domain signal X _n ;

The first spread spectrum sequence generation module is used for using the key key as a random number seed to generate a binary pseudo-random spread spectrum sequence u with a length of freqmax1-freqmin1+1;

The watermark embedding module is used to embed the watermark according to the spread spectrum sequence u, the frequency domain signal _Xn and the watermark bit b, and obtain the frequency domain signal after embedding the watermark. The calculation is as follows:

|X′ _n |=|X _n |+bαu

Among them, α is a constant, which controls the embedding strength of the watermark, and |X _n | and |X′ _n | represent the frequency domain amplitude before and after embedding the watermark, respectively. frequency domain signal

Among them, ∠X _n represents the phase of the frequency domain signal, X′ _n represents the frequency domain signal after embedding the watermark, and e is the mathematical natural exponent;

The time-frequency inverse transform module is used to transform the watermark-embedded frequency-domain signal X′ _n into the time-domain to generate a watermark-embedded audio file;

The watermark detection subsystem includes the following modules,

Select an appropriate area detection module to read the audio file to be detected, and obtain the nth frame signal z _n and sampling rate fs2 after time domain framing,

First, judge whether each frame of signal x _n can be used as an embedded area;

For each frame signal x _n that can be used as the embedded area, as the signal to be detected, calculate the starting point freqmin2 of the detection range and the end point freqmax2 of the frequency domain

freqmin2=floor((FWMIN×2.0/fs2)×N)

freqmax2=floor((FWMAX×2.0/fs2)×N)

The second time-frequency conversion module is used to perform discrete Fourier transform to obtain the frequency domain signal Z _n of the signal to be detected, and the corresponding frequency domain amplitude value is denoted as |Z _n |;

The second spread spectrum sequence generation module is used to use the key key as a random number seed to generate a binary pseudo-random spread spectrum sequence u with a length of freqmax2-freqmin2+1;

The correlation detection module is used to calculate the sufficient statistic r _n for detection according to the spread spectrum sequence u and the frequency domain amplitude value |Z _n | of the signal to be detected, as follows:

If the sufficient statistic rn _≥ 0, the detected watermark bit is b=1; otherwise, the detected watermark bit is b=0.

Moreover, in the selection of the appropriate region embedding module and the selection of the appropriate region detection module, the determination of whether each frame of signal x _n can be used as an embedded region is implemented as follows:

1) Average energy of signal x _n The size of τ exceeds the preset corresponding threshold τ ₁ , if it is, it is a silent zone, and watermarking is not allowed;

2) If the signal x _n contains a transient signal, it is not allowed to embed the watermark.

Moreover, whether a transient signal is included in the signal x _n is determined by the following method:

Suppose a frame of signal is decomposed into S blocks, and the energy of the S blocks is calculated respectively, and the energy ratio rate of the block with the maximum energy and the minimum energy block is compared with the preset corresponding threshold τ ₂ , if the rate is greater than τ ₂ , it is considered that the The frame signal contains transient signals.

The invention proposes to filter out the transient signal through the ratio of the maximum energy to the minimum energy in the frame to improve the accuracy of watermark detection, and to improve the robustness of the watermark by embedding the watermark in a frequency band that is significantly perceived by the human ear. Average energy to filter out quiet areas to improve perceived transparency. The technical solution of the present invention has important market value.

Description of drawings

FIG. 1 is a structural block diagram of an embedded subsystem according to an embodiment of the present invention.

FIG. 2 is a structural block diagram of a detection subsystem according to an embodiment of the present invention.

FIG. 3 is a flowchart of an embedding process according to an embodiment of the present invention

FIG. 4 is a flowchart of a detection process according to an embodiment of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below with specific embodiments in conjunction with the accompanying drawings.

Embodiments of the present invention provide an audio watermarking system based on embedding region selection, including an audio watermark embedding subsystem and a watermark detection subsystem.

Referring to FIG. 1 , an audio watermarking technology embedding subsystem for embedding region selection provided by an embodiment of the present invention includes an embedding module 1 for selecting an appropriate region, a first time-frequency conversion module 2, a first spreading sequence generation module 3, and a watermark embedding module 4 and time-frequency inverse transformation module 5, each module can be realized by software curing technology during specific implementation.

Described selecting a suitable area embedding module 1, judges the read time domain audio signal frame, and can judge whether the condition of embedding watermark can be met frame by frame during specific implementation: skip this frame if not met, and continue the judgment of the next frame If it is satisfied, the signal is output to the first time-frequency conversion module 2, and the range of the watermark embedded in this frequency-domain signal is calculated according to the read sampling rate of the time-domain audio signal and the frequency range to which the human ear is more sensitive, and the embedded watermark is The frequency domain signal within the range is output to the watermark embedding module 4, and the maximum value and the minimum value of the embedding range are output to the first spread spectrum sequence generation module 3;

The first time-frequency conversion module 2 is used to convert the read time-domain audio signal into a frequency-domain signal, and output to the watermark embedding module 4;

The first spreading sequence generation module 3 is used to generate a uniform distribution with an amplitude of 1 or -1 having the same length as the embedding range according to the random number seed and the maximum and minimum values of the embedding range input by the selection of the appropriate region embedding module 1. and output the random sequence to the watermark embedding module 4;

The watermark embedding module 4, for the amplitude spectrum in the frequency domain signal, generates an audio signal with watermark information in the frequency domain and outputs it to the time-frequency inverse transform module 5;

The time-frequency inverse transformation module 5 is used to convert the audio signal with watermark information in the frequency domain input by the watermark embedding module 4 into the audio signal with watermark information in the time domain, and convert the audio signal with watermark information in the time domain. The audio signal of the information generates an audio file, and an audio file with watermark information is obtained.

Referring to FIG. 2 , the watermark detection subsystem provided by the embodiment of the present invention includes a suitable region detection module 6 , a second time-frequency conversion module 7 , a second spread spectrum sequence generation module 8 , and a correlation detection module 9 , which can be used in specific implementation. Software curing technology realizes each module.

The function of the selecting a suitable region detection module 6 is basically the same as that of the selecting a suitable region embedding module 1. The region that does not meet the watermark embedding conditions generally does not contain a watermark. For frames that meet the detection conditions, skip the non-detection and continue the judgment of the next frame; the audio signals that meet the detection conditions are output to the second time-frequency transformation module 7, and the maximum and minimum values of the frequency detection area are also output to the second time-frequency conversion module 7. a frequency conversion module 7 and a second spread spectrum sequence generation module 8;

The second time-frequency conversion module 7 is used to convert the read time-domain audio signal into a frequency-domain signal, and output to the correlation detection module 9;

The second spread spectrum sequence generation module 8 has basically the same function as the first spread spectrum sequence generation module 3, and outputs the generated result to the correlation detection module 9;

The correlation detection module 9 is used to calculate the correlation value of the input frequency domain amplitude signal to be detected and the spread spectrum sequence input by the spread spectrum sequence generation module 9 according to the detection range, and determine the watermark according to the sign of the correlation value.

For the specific implementation of each module, refer to the corresponding steps of the method, which will not be repeated in the present invention. The audio watermarking method based on embedding region selection provided by the embodiment of the present invention includes an embedding process and a detection process.

Referring to FIG. 3, the audio watermark embedding process based on the selection area provided by the embodiment of the present invention can be automatically performed by computer software technical means, and specifically includes the following steps:

Step A1, read the audio file, first divide the time domain audio signal x into frames, obtain the sampling rate fs1 and the nth frame time domain audio signal x _n (frame length is N) after the framing, and for each frame signal x _n To judge whether it can be used as an embedded area, the judgment includes two aspects:

1) Determine whether the average energy of x _n exceeds the set threshold to determine whether the current frame x _n is a silent area. If it is a silent area, it is not allowed to embed a watermark. Otherwise, if it exceeds the threshold, it is not a silent area and may be embedded. Calculate the average energy of the nth frame by the following formula

Among them, N is the frame length, that is, the number of sample points in a frame; i is the index number of the sample points in a frame, ranging from 0 to N-1; x _n ² (i) represents the nth frame time domain signal The energy of x _n at the i-th point in the frame; τ ₁ is the judgment threshold of the average energy, and those skilled in the art can preset the value by themselves during the specific implementation, such as obtained from experience; if the threshold is exceeded, then condition 1) is satisfied, and the The judgment of the following condition 2).

2) For the case of transient signals in a frame, due to the drastic change of its frequency, it will cause a large variance. The larger the signal variance during detection, the higher the error probability of watermark detection. This situation should not be Embed a watermark. By decomposing a frame into S blocks, the energies of the S blocks are calculated respectively. By comparing the energy ratio rate of the block with the maximum energy to the block with the minimum energy and the threshold τ ₂ , if the rate is greater than τ ₂ , it is considered that the frame signal contains Transient signals are not watermarked, otherwise watermarks can be embedded. During specific implementation, those skilled in the art can preset the value of S by themselves.

The specific implementation is as follows:

First divide a frame of signal x _n into S blocks, then the number of sample points M in each sub-block is

M=N/S (2)

The energy E _i of each block is calculated as follows

Among them, i represents the index number of the intra-frame block, j represents the index number of the sample point in the frame, and x _n ² (j) represents the energy of the n-th frame time domain signal x _n at the j-th point in the frame.

Find the maximum energy E _Max and the minimum energy E _Min in the block energy

E _Max =MAX{E _i }, E _Min =MIN{E _i }, i∈[0,S-1] (4)

Among them, MAX and MIN represent the maximum value function and the minimum value function, respectively.

The ratio of the maximum energy to the minimum energy rate is calculated as follows:

If rate>τ ₂ , it is considered that there is a transient signal in the signal frame x _n , and no watermark is embedded in this frame; otherwise, a watermark can be embedded. Wherein τ ₂ is a threshold value, and those skilled in the art can preset a value during specific implementation. For example, τ ₂ is a detection threshold value of a transient signal, which is obtained according to experience.

Then, for each frame signal x _n that can be used as an embedded area, the selection of the embedded frequency segment of the audio watermark should be an area where the human ear perceives more prominently. Those skilled in the art can preset it according to the human ear perception characteristics, for example, 1000- 7000Hz. Because the signals in these areas will not be removed after filtering, audio compression and other attacks. Therefore, if the watermark is embedded in a perceptually obvious area, it will not be erased after some signal attacks and can be detected. Assume that the preset start frequency of the embedding according to the frequency part that the human ear is sensitive to is FWMIN and the end frequency is FWMAX, and the corresponding start embedding point freqmin1 and embedding end point freqmax1 of a frame are calculated as follows:

freqmin1=floor((FWMIN×2.0/fs1)×N) (6)

freqmax1=floor((FWMAX×2.0/fs1)×N) (7)

Among them, floor is the round-down function.

According to the start embedding point freqmin1 and the embedding end point freqmax1, the frequency domain audio signal within this range is selected.

During specific implementation, it can be judged frame by frame, and if the condition is not satisfied, the judgment of the next frame can be performed.

Step A2, perform FFT transformation (Fast Discrete Fourier Transform) on the signal frame x _n capable of embedding the watermark into the frequency domain signal X _n .

Step A3, using the key key as a random number seed, a binary pseudo-random spread spectrum sequence u with a length of freqmax1-freqmin1+1 is generated.

The specific process of the embodiment in MATLAB is as follows:

First, use the key key to call the RandStream function (random seed function) to initialize the rand function (random number generation function), and then call the rand function to generate a random number, since the random number generated by the rand function is a number between 0 and 1 , it is necessary to round these numbers into a binary pseudo-random sequence of 0 and 1, and then convert this unipolar pseudo-random sequence into a bi-polar pseudo-random sequence u that only contains +1 and -1.

Step A4, according to the spread spectrum sequence u, the frequency domain signal X _n and the watermark bit b, use the following formula (8) to embed the watermark to obtain the frequency domain signal after embedding the watermark, and the calculation is implemented as follows:

|X′ _n |=|X _n |+bαu (8)

Among them, α is a constant, which controls the embedding strength of the watermark, and can be preset by those skilled in the art during the specific implementation; |X _n | and |X' _n | represent the frequency domain amplitude before the watermark is embedded and the value after the watermark is embedded, respectively. Frequency domain amplitude, and then obtain the frequency domain signal after embedding the watermark through Euler's formula.

Among them, ∠X _n represents the phase of the frequency domain signal, X′ _n represents the frequency domain signal after embedding the watermark, and e is the mathematical natural exponent.

Step A5, transform the watermark-embedded frequency-domain signal _X'n into the time-domain, and finally generate an audio file, that is, obtain a watermark-embedded audio file.

Referring to FIG. 4 , the audio watermark detection process based on selection area embedding provided by the embodiment of the present invention can be automatically performed by computer software technical means, and specifically includes the following steps:

Step B1, read the audio file to be detected, obtain the n-th frame signal z _n and the sampling rate fs2 after the time domain is divided into frames, and adopt the same judgment method in step A1 for each time domain signal z _n ,

That is, considering the following two conditions,

1) Average energy of signal x _n The size of τ exceeds the preset corresponding threshold τ ₁ , if it is, it is a silent zone, and watermarking is not allowed;

2) If the signal x _n contains a transient signal, it is not allowed to embed the watermark.

Then the frame signal that is not a silent zone and does not contain transient signals can be embedded with a watermark and needs to be detected.

During specific implementation, it can be judged frame by frame, and if the condition is not satisfied, the judgment of the next frame can be performed.

For each frame signal x _n that can be used as the embedded area, as the signal to be detected, calculate the frequency domain start point freqmin2 and the frequency domain end point freqmax2 of the detection range

freqmin2=floor((FWMIN×2.0/fs2)×N) (10)

freqmax2=floor((FWMAX×2.0/fs2)×N) (11)

Step B2, for the signal z _n that satisfies the detection condition, perform discrete Fourier transform to obtain the frequency domain signal Zn of the signal to be detected, and the corresponding frequency domain amplitude value _{is denoted as |Z n |} .

Step B3, use the key key to generate a binary spread spectrum sequence u (same as the u obtained by the above embedding method), that is, use the key key as a random number seed to generate a binary pseudo-random spread spectrum with a length of freqmax2-freqmin2+1 sequence u.

Step B4, according to the spread spectrum sequence u and the frequency domain amplitude value |Z _n | of the signal to be detected, by calculating the correlation value between the spread spectrum sequence u and the frequency domain amplitude value |Z _n | statistic r _n

Among them, <·> represents the inner product calculation of the signal.

If the sufficient statistic rn _≥ 0, the detected watermark bit is b=1; otherwise, the detected watermark bit is b=0.

The specific embodiments described in the present invention are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or additions to the described specific embodiments or substitute in similar manners, but will not deviate from the spirit of the present invention or go beyond the definitions of the appended claims range.

Claims (6)

1. a kind of audio-frequency water mark method based on insertion regional choice, it is characterised in that: including telescopiny and detection process, institute Telescopiny is stated to include the following steps,

Step A1 reads audio file, obtains the signal x of n-th frame time-domain audio after sample rate f s1 and framing_n, frame length N, first To every frame signal x_nBe made whether can as insertion region judgement,

Then being directed to can be as each frame signal x in insertion region_n, the selection of the insertion frequency band of audio frequency watermark is carried out, if according to The start frequency of the preset insertion of frequency-portions of auditory perceptual sensitivity is FWMIN, end frequency is FWMAX, the beginning of a frame Insertion point freqmin1 and be embedded in end point freqmax1 seek it is as follows,

Freqmin1=floor ((FWMIN × 2.0/fs1) × N)

Freqmax1=floor ((FWMAX × 2.0/fs1) × N)

Wherein, floor is downward bracket function；

Step A2, to each frame signal x that can be embedded in watermark_n, carry out Discrete Fourier Transform and obtain frequency domain signal X_n；

It is pseudo- to generate the binary system that length is freqmax1-freqmin1+1 using key key as random number seed by step A3 Random frequency expansion sequence u；

Step A4, according to frequency expansion sequence u, frequency domain signal X_nWith watermark bit b, the insertion of watermark is carried out, after obtaining insertion watermark Frequency-region signal, calculating is as follows,

|X′_n|=| X_n|+bαu

Wherein, α is constant, controls the embedment strength of watermark, | X_n| and | X '_n| respectively indicate insertion watermark before frequency domain amplitude and Then frequency domain amplitude after being embedded in watermark obtains the frequency-region signal after insertion watermark by Euler's formula

Wherein, ∠ X_nIndicate the phase of frequency-region signal, X '_nFrequency-region signal after indicating insertion watermark, e are mathematics natural Exponents, on Mark j is imaginary unit；

Step A5, by be embedded in watermark after frequency domain signal X '_nTime domain is transformed to, the audio file of insertion watermark is generated；

The detection process includes the following steps,

Step B1 reads audio file to be detected, the n-th frame signal z after obtained time domain framing_nIt is first right with sample rate f s2 Every frame signal x_nBeing made whether can be as the judgement in insertion region；

For each frame signal x that can be used as insertion region_n, as signal to be detected, calculate the starting point of detection range Freqmin2 and frequency domain end point freqmax2

Freqmin2=floor ((FWMIN × 2.0/fs2) × N)

Freqmax2=floor ((FWMAX × 2.0/fs2) × N)

Step B2 carries out Discrete Fourier Transform and obtains the frequency-region signal Z of signal to be detected_n, corresponding frequency domain range value is denoted as | Z_n |；

It is pseudo- to generate the binary system that length is freqmax2-freqmin2+1 using key key as random number seed by step B3 Random frequency expansion sequence u；

Step B4, according to the frequency domain range value of frequency expansion sequence u and signal to be detected | Z_n|, calculate the sufficient statistic r of detection_n It is as follows,

If sufficient statistic r_n>=0, then the watermark bit detected is b=1；Otherwise, the watermark bit detected is b= 0。

2. the audio-frequency water mark method according to claim 1 based on insertion regional choice, it is characterised in that: step A1 and step In B1, to every frame signal x_nBeing made whether can be as the judgement in insertion region, and implementation is as follows,

1) signal x_nAverage energySize exceed preset respective threshold τ₁, it is then not allow to be embedded in water for mute area Print；

The average energy of n-th frame is calculated by following formula

Wherein, N is frame length, and i is the sample point index number in a frame, x_n ²(i) n-th frame time-domain signal x is indicated_nI-th in frame The energy of point；τ₁For the decision threshold of average energy；

If 2) signal x_nInterior includes transient signal, then does not allow to be embedded in watermark.

3. the audio-frequency water mark method according to claim 2 based on insertion regional choice, it is characterised in that: signal x_nInside whether Comprising transient signal, it is judged by the following manner,

If a frame signal is decomposed into S block, the energy of S block is calculated separately out, compares the block and least energy of ceiling capacity The energy ratio rate of block and preset respective threshold τ₂If rate is greater than τ₂Then think that the frame signal includes transient signal.

4. it is a kind of based on insertion regional choice audio frequency watermark system, it is characterised in that: including audio frequency watermark insertion subsystem and Watermark detection subsystem,

The audio frequency watermark insertion subsystem comprises the following modules,

Selection appropriate area insertion module obtains n-th frame time-domain audio after sample rate f s1 and framing for reading audio file Signal x_n, frame length N,

First to every frame signal x_nBe made whether can as insertion region judgement,

Then being directed to can be as each frame signal x in insertion region_n, the selection of the insertion frequency band of audio frequency watermark is carried out, if according to The start frequency of the preset insertion of frequency-portions of auditory perceptual sensitivity is FWMIN, end frequency is FWMAX, the beginning of a frame Insertion point freqmin1 and be embedded in end point freqmax1 seek it is as follows,

Freqmin1=floor ((FWMIN × 2.0/fs1) × N)

Freqmax1=floor ((FWMAX × 2.0/fs1) × N)

Wherein, floor is downward bracket function；

First time-frequency convert module, for each frame signal x that can be embedded in watermark_n, carry out Discrete Fourier Transform and obtain frequency domain Signal X_n；

First frequency expansion sequence generation module, for using key key as random number seed, generation length to be freqmax1- The pseudorandom frequency expansion sequence u of the binary system of freqmin1+1；

Watermark embedding module, for according to frequency expansion sequence u, frequency domain signal X_nWith watermark bit b, the insertion of watermark is carried out, is obtained embedding Frequency-region signal after entering watermark, calculating is as follows,

|X′_n|=| X_n|+bαu

Wherein, α is constant, controls the embedment strength of watermark, | X_n| and | X '_n| respectively indicate insertion watermark before frequency domain amplitude and Then frequency domain amplitude after being embedded in watermark obtains the frequency-region signal after insertion watermark by Euler's formula

Wherein, ∠ X_nIndicate the phase of frequency-region signal, X '_nFrequency-region signal after indicating insertion watermark, e are mathematics natural Exponents, on Mark j is imaginary unit；

Time-frequency inverse transform module, for will be embedded in the frequency domain signal X after watermark '_nTime domain is transformed to, the audio of insertion watermark is generated File；

The watermark detection subsystem comprises the following modules,

Select appropriate area detection module, for reading audio file to be detected, the n-th frame signal after obtained time domain framing z_nWith sample rate f s2,

First to every frame signal x_nBeing made whether can be as the judgement in insertion region；

For each frame signal x that can be used as insertion region_n, as signal to be detected, calculate the starting point of detection range Freqmin2 and frequency domain end point freqmax2

Freqmin2=floor ((FWMIN × 2.0/fs2) × N)

Freqmax2=floor ((FWMAX × 2.0/fs2) × N)

Second time-frequency convert module obtains the frequency-region signal Z of signal to be detected for carrying out Discrete Fourier Transform_n, corresponding frequency domain Range value is denoted as | Z_n|；

Second frequency expansion sequence generation module, for using key key as random number seed, generation length to be freqmax2- The pseudorandom frequency expansion sequence u of the binary system of freqmin2+1；

Coherent detection module, for the frequency domain range value according to frequency expansion sequence u and signal to be detected | Z_n|, calculate filling for detection Divide statistic r_nIt is as follows,

If sufficient statistic r_n>=0, then the watermark bit detected is b=1；Otherwise, the watermark bit detected is b= 0。

5. the audio frequency watermark system according to claim 4 based on insertion regional choice, it is characterised in that: selection appropriate area It is embedded in module and selection appropriate area detection module, to every frame signal x_nBe made whether can as insertion region judgement, Implementation is as follows,

1) signal x_nAverage energySize exceed preset respective threshold τ₁, it is then not allow to be embedded in water for mute area Print；

The average energy of n-th frame is calculated by following formula

Wherein, N is frame length, and i is the sample point index number in a frame, x_n ²(i) n-th frame time-domain signal x is indicated_nI-th in frame The energy of point；τ₁For the decision threshold of average energy；

If 2) signal x_nInterior includes transient signal, then does not allow to be embedded in watermark.

6. the audio frequency watermark system according to claim 5 based on insertion regional choice, it is characterised in that: signal x_nInside whether Comprising transient signal, it is judged by the following manner,

If a frame signal is decomposed into S block, the energy of S block is calculated separately out, compares the block and least energy of ceiling capacity The energy ratio rate of block and preset respective threshold τ₂If rate is greater than τ₂Then think that the frame signal includes transient signal.