Audio recording and converting method for Bluetooth earphone

Abstract

The invention discloses an audio recording and conversion method for a Bluetooth headset, and particularly relates to the field of audio recording conversion. The audio recording and conversion method comprises the steps that a Bluetooth function of sound source equipment is started, and the sound source equipment is connected with the Bluetooth headset in a paired mode; then, a recording process is started through a recording button on the earphone, and the system guides the user to select an audio format and confirm recording setting; in the recording period, a built-in microphone of the earphone collects audio signals in real time, the collected audio signals are subjected to denoising and signal amplification processing, and then the processed audio signals are converted into digital signals; embedding a watermark into the processed digital signal, calculating a watermark evaluation value, and comparing and verifying whether the watermark is embedded or not through the watermark evaluation value; the method comprises the following steps: firstly, converting a digital signal into an analog signal, reconstructing the analog signal into an audio signal, and finally, carrying out watermark detection on the reconstructed audio signal by a system, and comparing detected watermark information to ensure the integrity and authenticity of audio signal data.

Description

Technical Field

[0001] The present invention relates to the technical field of audio recording conversion, and more specifically, to an audio recording and conversion method for a Bluetooth headset. Background Art

[0002] In today's fast-paced digital age, Bluetooth headsets, as the representative of personal audio devices, have penetrated into every aspect of our lives, from daily commuting to sports and fitness, to remote work and online education. Bluetooth headsets have won a broad user base with their convenience, wireless freedom and high-quality sound performance; however, with the advancement of technology and the diversification of application scenarios, users' functional demands for Bluetooth headsets are also growing, especially in terms of audio security conversion and management, which has become an important issue that needs to be urgently addressed.

[0003] However, in actual use, traditional Bluetooth headset audio recording still has some shortcomings. For example, traditional Bluetooth headsets mainly focus on the stability and sound quality of audio transmission, and have obvious deficiencies in the confidentiality of converted audio recording data. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides an audio recording and conversion method for a Bluetooth headset to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] Step A1: Turn on the Bluetooth function of the audio source device, pair it via Bluetooth, and confirm the recording settings;

[0007] Step A2: During the recording process, the built-in microphone of the Bluetooth headset collects audio signals in real time, and processes the collected audio signals to obtain digital signals;

[0008] Step A3: embedding the processed digital signal into a watermark, and calculating a watermark evaluation value based on the embedded watermark;

[0009] Step A4: converting the watermarked digital signal into an analog signal and reconstructing the audio signal;

[0010] Step A5: Perform watermark detection on the reconstructed audio signal and compare the detected watermarks.

[0011] Preferably, in step A1, after the Bluetooth of the sound source device is turned on, ensure that it is in the "discoverable" state so that nearby Bluetooth devices can search for it; for the Bluetooth audio device to be connected, enter the pairing mode according to the instructions in the instruction manual; in the Bluetooth setting page of the sound source device, click "Search Device" to let the device start scanning nearby Bluetooth devices; in the scan results, find the name of the connected Bluetooth audio device and click it.

[0012] The user touches the dedicated "recording" button on the Bluetooth headset, and the built-in microphone of the Bluetooth headset is immediately activated and ready to receive sound signals; at the same time, the Bluetooth headset sends a recording start signal to the paired smart device through the Bluetooth connection. After the paired smart device receives the recording start signal, a recording application notification pops up on the screen; the system prompts the user with a friendly interface and clear language: "Recording is about to start, please select the audio format you want;" the user selects the WAV audio format from the options provided on the interface according to needs. After selecting the audio format, the system will display an overview of the current recording settings; the user needs to carefully check these settings to ensure that they meet their needs; if modifications are required, the user clicks the corresponding option to make adjustments; after confirming the recording settings, the user clicks the "Start Recording" button, and the system starts recording according to the set parameters.

[0013] Preferably, in step A2, the collected audio signal is amplified and denoised, and the denoising method is specifically as follows:

[0014] Step B1 preprocesses the collected audio signal, the preprocessing includes removing the DC component and applying a window function at the front end of the signal to reduce the impact of noise during processing;

[0015] Step B2: Use fast Fourier transform to convert the time domain signal into frequency domain representation; after obtaining the spectrum, represent the spectrum as amplitude spectrum and phase spectrum;

[0016] Step B3: Select a segment that does not contain useful signals for noise estimation; calculate the frequency spectrum of the noise segment to obtain the amplitude spectrum of the segment;

[0017] In this step, smoothing is applied to the spectrum of the noise to obtain a more stable noise model;

[0018] Step B4: Perform spectral subtraction on the amplitude spectrum of the original signal to obtain a second amplitude spectrum. The calculation method of the second amplitude spectrum is specifically as follows:

[0019] Wherein, F(a) represents the second amplitude spectrum obtained after removing noise, G(a) represents the estimated noise amplitude spectrum; H(a) represents the amplitude spectrum of the noise signal, β represents an over-subtraction factor used to further reduce the residual noise; max represents the comparison of two values ​​and selects the larger one;

[0020] Step B5: A new spectrum is constructed by combining the denoised amplitude spectrum with the phase spectrum of the original signal. The calculation method of the new spectrum is as follows:

[0021] Among them, F(a)0 represents the newly constructed spectrum, F(a) represents the second amplitude spectrum obtained after removing the noise, and e L(a) It is represented as the phase spectrum of the original noisy signal, and δ(a) is represented as the phase angle of the ath frequency component;

[0022] Step B6: Use inverse fast Fourier transform to convert the denoised spectrum back to the time domain to obtain the processed audio signal.

[0023] The specific method of amplifying the audio signal is as follows:

[0024] Step C1: Convert the denoised audio signal into an electrical signal.

[0025] This electrical signal is usually very weak and may only be detectable by delicate electronic components.

[0026] Step C2: The weak audio signal enters the preamplifier, which increases the strength of the weak signal to a processable level;

[0027] Step C3: The preamplifier has a gain adjustment function, and the user sets the gain value as needed.

[0028] Among them, gain refers to the ratio of signal amplification. Reasonable gain setting ensures that the audio signal will not be overly distorted or introduce noise;

[0029] Step C4: The amplified signal undergoes subsequent digital signal processing, the signal is further clarified, and various audio effects are applied.

[0030] Preferably, in step A3, after embedding the digital signal into the watermark, the method for calculating the watermark evaluation value and the watermark stability value is specifically as follows:

[0031] W d =X(D+I), where W d It is represented as the watermark stability value, X is represented as the correlation coefficient, I is represented as the frequency domain watermark evaluation value, and D is represented as the first capacity value;

[0032] The specific calculation method of the watermark sampling ratio is:

[0033] Where Z represents the watermark sampling ratio, q(b) represents the sampling value of the host audio signal before the watermark is embedded in the audio, q0(b) represents the sampling value of the host audio signal after the watermark is embedded in the audio, and T represents the total number of samples;

[0034] The specific calculation method of the watermark evaluation value is:

[0035] Among them, Q represents the watermark evaluation value, X represents the correlation coefficient, Z represents the watermark sampling ratio, and W d Represented as the watermark stability value.

[0036] Preferably, in step A4, a DAC device is selected, a reference voltage, an output range, and a resolution of the DAC are set, and a digital signal for conversion is extracted; the prepared digital signal value is written into a data input register of the DAC, and the conversion is waited for to start; according to the design of the DAC, the conversion is triggered by an external signal, and during the conversion process, it is ensured that the clock signal of the DAC is correct so that the digital signal can be converted as planned;

[0037] After the DAC completes the conversion, a stable analog signal is obtained at the output end; this process is affected by the DAC's settling time; the output analog signal is smoothed through a filter to obtain a more natural audio waveform. After the DAC and filtering, the signal is converted into a continuous analog waveform, and the continuous analog waveform is the reconstructed audio signal.

[0038] Preferably, in step A5, watermark information is extracted from the reconstructed audio signal, and the extracted watermark information is calculated to obtain a watermark similarity value. The specific method for calculating the watermark similarity value is:

[0039] Where V represents the watermark similarity value, S represents the sample point, M represents the number of audio frames, and N(e, f) represents the amplitude value of the fth frequency point in the eth frame;

[0040] Calculation is performed based on the calculated watermark similarity value. If the calculated watermark similarity value is equal to the preset watermark similarity value threshold, a safety instruction is output to store the audio signal in the built-in memory of the Bluetooth headset; if the calculated watermark similarity value is not equal to the preset watermark similarity value threshold, a danger instruction is output and go to step A2.

[0041] Technical effects and advantages of the present invention:

[0042] The present invention provides an audio recording and conversion method for a Bluetooth headset. The present invention supports direct recording and audio format selection on the Bluetooth headset through Bluetooth pairing connection of an audio source device. The system automatically processes and embeds a watermark into the recorded audio signal, and then converts the digital signal into an analog signal to reconstruct the audio output; finally, the system performs watermark detection on the reconstructed audio to ensure the security and integrity of the audio data. This method enhances the confidentiality and security of the recorded data, and the reconstructed audio signal is of high quality, providing users with a more natural and realistic auditory experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] See also Figure 1 As shown, the present invention provides an audio recording and conversion method for a Bluetooth headset, comprising the following steps:

[0046] Step A1: Turn on the Bluetooth function of the audio source device, pair it via Bluetooth, and confirm the recording settings;

[0047] In step A1, after turning on the Bluetooth of the audio source device, ensure that it is in the "discoverable" state so that nearby Bluetooth devices can search for it; for the Bluetooth audio device to be connected, enter the pairing mode according to the instructions in the instruction manual; in the Bluetooth setting page of the audio source device, click "Search Device" to let the device start scanning nearby Bluetooth devices; in the scan results, find the name of the connected Bluetooth audio device and click it, at this time, the audio source device is connected to the Bluetooth audio device.

[0048] When the user taps the dedicated "recording" button on the Bluetooth headset, the built-in microphone of the Bluetooth headset is activated immediately and is ready to receive sound signals; at the same time, the Bluetooth headset sends a recording start signal to the paired smart device through the Bluetooth connection. After the paired smart device receives the recording start signal, a recording application notification pops up on the screen; the system prompts the user with a friendly interface and clear language: "Recording is about to start, please select the audio format you want;" the user selects the WAV audio format from the options provided on the interface according to needs. After selecting the audio format, the system displays an overview of the current recording settings; the user needs to carefully check these settings to ensure that they meet their needs; if modifications are required, the user clicks the corresponding option to adjust; after confirming the recording settings, the user clicks the "Start Recording" button, and the system starts recording according to the set parameters;

[0049] Among them, the recording setting parameters include the selected format, recording quality, and whether to enable the noise reduction function; the WAV format can maintain high sound quality.

[0050] Step A2: During the recording process, the built-in microphone of the Bluetooth headset collects audio signals in real time, and processes the collected audio signals to obtain digital signals;

[0051] In step A2, the collected audio signal is amplified and denoised, and the denoising method is specifically as follows:

[0052] Step B1 preprocesses the collected audio signal, the preprocessing includes removing the DC component and applying a window function at the front end of the signal to reduce the impact of noise during processing;

[0053] Step B2: Use fast Fourier transform to convert the time domain signal into frequency domain representation; after obtaining the spectrum, represent the spectrum as amplitude spectrum and phase spectrum;

[0054] Step B3: Select a segment that does not contain useful signals for noise estimation; calculate the frequency spectrum of the noise segment to obtain the amplitude spectrum of the segment;

[0055] In this step, smoothing is applied to the spectrum of the noise to obtain a more stable noise model;

[0056] Step B4: Perform spectral subtraction on the amplitude spectrum of the original signal to obtain a second amplitude spectrum. The calculation method of the second amplitude spectrum is specifically as follows:

[0057] Wherein, F(a) represents the second amplitude spectrum obtained after removing noise, G(a) represents the estimated noise amplitude spectrum; H(a) represents the amplitude spectrum of the noise signal, β represents an over-subtraction factor used to further reduce the residual noise; max represents the comparison of two values ​​and selects the larger one;

[0058] Step B5: A new spectrum is constructed by combining the denoised amplitude spectrum with the phase spectrum of the original signal. The calculation method of the new spectrum is as follows:

[0059] Among them, F(a)0 represents the newly constructed spectrum, F(a) represents the second amplitude spectrum obtained after removing the noise, and e L(a) It is represented as the phase spectrum of the original noisy signal, and δ(a) is represented as the phase angle of the ath frequency component;

[0060] Step B6: using inverse fast Fourier transform to convert the denoised spectrum back to the time domain to obtain a processed audio signal;

[0061] Perform sound detection on the denoised audio, and determine whether the denoised audio has sound by the audio confirmation value. The specific calculation method of the audio confirmation value is as follows:

[0062] Where R represents the audio confirmation value, N(e, f) represents the amplitude value of the fth frequency point in the eth frame, H represents the total number of audio frames, ρ represents the spectrum window length, and f max Expressed as the upper limit of the frequency amplitude value, f min It is expressed as the lower limit of the frequency amplitude value;

[0063] The pre-processed audio signal to be tested is framed and windowed, with a frame length of 32 milliseconds, a frame shift of 16 milliseconds, and a Hamming window; then a Fourier transform with a length of 8192 points is performed to obtain the audio signal to be tested;

[0064] Frame Windowing: Divide the audio signal into consecutive frames, each with a length of 32 milliseconds, and there is a 16 millisecond overlap (frame shift) between adjacent frames. This is done to capture the time-varying characteristics of the signal when analyzing the audio signal.

[0065] Hamming window: To reduce spectrum leakage, each frame is multiplied by a Hamming window function. The Hamming window is a commonly used window function that can provide better frequency resolution and lower sidelobe levels in the frequency domain;

[0066] Fourier transform: Perform 8192-point Fourier transform on each windowed frame, which converts the audio signal from the time domain to the frequency domain to obtain a spectrum signal.

[0067] The specific calculation method of N(e, f) is:

[0068] Wherein, N(e, f) represents the amplitude value of the fth frequency point in the eth frame, T represents the harmonic value, and ρ represents the spectrum window length;

[0069] The calculated audio confirmation value is compared with a preset audio confirmation value threshold value. If the calculated audio confirmation value is greater than the preset audio confirmation value threshold value, it is determined that the audio has sound; if the calculated audio confirmation value is less than the preset audio confirmation value threshold value, it is determined that the audio has no sound;

[0070] The specific method of amplifying the audio signal is as follows:

[0071] Step C1: Convert the denoised audio signal into an electrical signal.

[0072] This electrical signal is usually very weak and may only be detectable by delicate electronic components.

[0073] Step C2: The weak audio signal enters the preamplifier, which increases the strength of the weak signal to a processable level;

[0074] Step C3: The preamplifier has a gain adjustment function, and the user sets the gain value as needed.

[0075] Among them, gain refers to the ratio of signal amplification. Reasonable gain setting ensures that the audio signal will not be overly distorted or introduce noise;

[0076] Step C4: The amplified signal undergoes subsequent digital signal processing, the signal is further clarified, and various audio effects are applied.

[0077] Step A3: embedding the processed digital signal into a watermark, and calculating a watermark evaluation value based on the embedded watermark;

[0078] In step A3, after the digital signal is embedded in the watermark, the watermark evaluation value is calculated. The calculation method of the first capacity value is specifically as follows:

[0079] Wherein, D represents the first capacity value, E represents the bandwidth of the audio carrier signal, J represents the watermark efficiency, and K represents the attack power;

[0080] The calculation method of the frequency domain watermark evaluation value is as follows:

[0081] Where I represents the frequency domain watermark evaluation value, a represents the sampling frequency of the audio signal, P represents the number of watermark bits embedded in each audio frequency domain segment, L represents the length of the audio time domain segment, R0 represents the number of audio time domain segments, and R1 represents the number of audio frequency domain segments;

[0082] The calculation method of the correlation coefficient is as follows:

[0083] Where X represents the correlation coefficient, t represents the bit value of the original watermark, and t0 represents the detected watermark bit value;

[0084] The specific calculation method of the watermark stability value is:

[0085] W d =X(D+I), where W d It is represented as the watermark stability value, X is represented as the correlation coefficient, I is represented as the frequency domain watermark evaluation value, and D is represented as the first capacity value;

[0086] The specific calculation method of the watermark sampling ratio is:

[0087] Where Z represents the watermark sampling ratio, q(b) represents the sampling value of the host audio signal before the watermark is embedded in the audio, q0(b) represents the sampling value of the host audio signal after the watermark is embedded in the audio, and T represents the total number of samples;

[0088] The specific calculation method of the watermark evaluation value is:

[0089] Among them, Q represents the watermark evaluation value, X represents the correlation coefficient, Z represents the watermark sampling ratio, and W d It is expressed as the watermark stability value;

[0090] The calculated watermark evaluation value is compared with the preset watermark evaluation threshold. If the calculated watermark evaluation value is greater than the preset watermark evaluation threshold, a success instruction is output and the process goes to step A5. If the calculated watermark evaluation value is less than the preset watermark evaluation threshold, a failure instruction is output and the watermark is re-embedded.

[0091] Step A4: converting the watermarked digital signal into an analog signal and reconstructing the audio signal;

[0092] In the step A4, a DAC device is selected, a reference voltage, an output range, and a resolution of the DAC are set, and a digital signal for conversion is extracted; the prepared digital signal value is written into a data input register of the DAC, and the conversion is waited for to start; according to the design of the DAC, the conversion is triggered by an external signal, and during the conversion process, the clock signal of the DAC is ensured to be correct so that the digital signal can be converted as planned;

[0093] After the DAC completes the conversion, a stable analog signal is obtained at the output end; this process is affected by the DAC's settling time; the output analog signal is smoothed through a filter to obtain a more natural audio waveform. After the DAC and filtering, the signal is converted into a continuous analog waveform, and the continuous analog waveform is the reconstructed audio signal.

[0094] DAC stands for Digital to Analog Conversion.

[0095] Step A5: Perform watermark detection on the reconstructed audio signal and compare the detected watermarks.

[0096] In step A5, watermark information is extracted from the reconstructed audio signal, and the extracted watermark information is calculated to obtain a watermark similarity value. The specific method for calculating the watermark similarity value is:

[0097] Where V represents the watermark similarity value, S represents the sample point, M represents the number of audio frames, and N(e, f) represents the amplitude value of the fth frequency point in the eth frame;

[0098] Calculation is performed based on the calculated watermark similarity value. If the calculated watermark similarity value is equal to the preset watermark similarity value threshold, a safety instruction is output to store the audio signal in the built-in memory of the Bluetooth headset; if the calculated watermark similarity value is not equal to the preset watermark similarity value threshold, a danger instruction is output and go to step A2.

[0099] It should be noted that the preset values ​​in the present invention are determined according to specific circumstances, that is, this embodiment does not specifically limit the specific values.

[0100] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An audio recording and conversion method for a Bluetooth headset, characterized in that: include: Step A1: Turn on the Bluetooth function of the audio source device, pair it via Bluetooth, and confirm the recording settings; Step A2: During the recording process, the built-in microphone of the Bluetooth headset collects audio signals in real time, and processes the collected audio signals to obtain digital signals; Step A3: embedding the processed digital signal into a watermark, and calculating a watermark evaluation value based on the embedded watermark; Step A4: converting the watermarked digital signal into an analog signal and reconstructing the audio signal; Step A5: Perform watermark detection on the reconstructed audio signal, and judge the detected watermark.

2. The method for audio recording and conversion for a Bluetooth headset according to claim 1, characterized in that: In step A2, the collected audio signal is amplified and denoised; the denoising method is specifically as follows: Step B1 preprocesses the collected audio signal, the preprocessing includes removing the DC component and applying a window function at the front end of the signal to reduce the impact of noise during processing; Step B2: Use fast Fourier transform to convert the time domain signal into frequency domain representation; after obtaining the spectrum, represent the spectrum as amplitude spectrum and phase spectrum; Step B3: Select a segment that does not contain useful signals for noise estimation; calculate the frequency spectrum of the noise segment to obtain the amplitude spectrum of the segment; Step B4: Perform spectral subtraction on the amplitude spectrum of the original signal to obtain a second amplitude spectrum. The calculation method of the second amplitude spectrum is specifically as follows: Wherein, F(a) represents the second amplitude spectrum obtained after removing noise, G(a) represents the estimated noise amplitude spectrum; H(a) represents the amplitude spectrum of the noise signal, β represents an over-subtraction factor used to further reduce the residual noise; max represents the comparison of two values ​​and selects the larger one; Step B5: A new spectrum is constructed by combining the denoised amplitude spectrum with the phase spectrum of the original signal. The calculation method of the new spectrum is as follows: Among them, F(a)0 represents the newly constructed spectrum, F(a) represents the second amplitude spectrum obtained after removing the noise, and e L(a) It is represented as the phase spectrum of the original noisy signal, and δ(a) is represented as the phase angle of the ath frequency component; Step B6: Use inverse fast Fourier transform to convert the denoised spectrum back to the time domain to obtain the processed audio signal.

3. The method for audio recording and conversion for a Bluetooth headset according to claim 2, characterized in that: Perform sound detection on the denoised audio, and determine whether the denoised audio has sound by the audio confirmation value. The specific calculation method of the audio confirmation value is as follows: Where R represents the audio confirmation value, N(e, f) represents the amplitude value of the fth frequency point in the eth frame, H represents the total number of audio frames, ρ represents the spectrum window length, and f max Expressed as the upper limit of the frequency amplitude value, f min It is expressed as the lower limit of the frequency amplitude value; The specific calculation method of N(e, f) is: Wherein, N(e, f) represents the amplitude value of the fth frequency point in the eth frame, T represents the harmonic value, and ρ represents the spectrum window length; The calculated audio confirmation value is compared with the preset audio confirmation value threshold. If the calculated audio confirmation value is greater than the preset audio confirmation value threshold, the audio is determined to have sound; if the calculated audio confirmation value is less than the preset audio confirmation value threshold, the audio is determined to have no sound.

4. The method for audio recording and conversion for a Bluetooth headset according to claim 1, characterized in that: In step A3, after the digital signal is embedded in the watermark, the watermark evaluation value is calculated. The calculation method of the first capacity value is specifically as follows: Wherein, D represents the first capacity value, E represents the bandwidth of the audio carrier signal, J represents the watermark efficiency, and K represents the attack power; The calculation method of the frequency domain watermark evaluation value is as follows: Among them, I represents the frequency domain watermark evaluation value, a represents the sampling frequency of the audio signal, P represents the number of watermark bits embedded in each audio frequency domain segment, L represents the length of the audio time domain segment, R0 represents the number of audio time domain segments, and R1 represents the number of audio frequency domain segments.

5. The method for audio recording and conversion for a Bluetooth headset according to claim 4, characterized in that: The specific calculation method of the watermark stability value is: W d =X(D+I), where W d It is represented as the watermark stability value, X is represented as the correlation coefficient, I is represented as the frequency domain watermark evaluation value, and D is represented as the first capacity value; The specific calculation method of the watermark sampling ratio is: Among them, Z represents the watermark sampling ratio, q(b) represents the sampling value of the host audio signal before the watermark is embedded in the audio, q0(b) represents the sampling value of the host audio signal after the watermark is embedded in the audio, and T represents the total number of samples.

6. The audio recording and conversion method for a Bluetooth headset according to claims 4 and 5, characterized in that: The specific calculation method of the watermark evaluation value is: Among them, Q represents the watermark evaluation value, X represents the correlation coefficient, Z represents the watermark sampling ratio, and W d Represented as the watermark stability value.

7. The method for audio recording and conversion for a Bluetooth headset according to claim 1, characterized in that: In the step A4, a DAC device is selected, a reference voltage, an output range, and a resolution of the DAC are set, and a digital signal for conversion is extracted; the prepared digital signal value is written into a data input register of the DAC, and the conversion is waited for to start; according to the design of the DAC, the conversion is triggered by an external signal, and during the conversion process, the clock signal of the DAC is ensured to be correct so that the digital signal can be converted as planned; After the DAC completes the conversion, a stable analog signal is obtained at the output end; the output analog signal is smoothed through a filter to obtain a more natural audio waveform. After passing through the DAC and filtering, the signal is converted into a continuous analog waveform, and the continuous analog waveform is the reconstructed audio signal.

8. The method for audio recording and conversion for a Bluetooth headset according to claim 1, characterized in that: In step A5, watermark information is extracted from the reconstructed audio signal, and the extracted watermark information is calculated to obtain a watermark similarity value. The specific method for calculating the watermark similarity value is: Where V represents the watermark similarity value, S represents the sample point, M represents the number of audio frames, and N(e, f) represents the amplitude value of the fth frequency point in the eth frame; Calculation is performed based on the calculated watermark similarity value. If the calculated watermark similarity value is equal to a preset watermark similarity value threshold, a safe instruction is output; if the calculated watermark similarity value is not equal to the preset watermark similarity value threshold, a dangerous instruction is output.

9. The method for audio recording and conversion for a Bluetooth headset according to claim 8, characterized in that: When the control end receives a safety instruction, the audio signal is stored in the built-in memory of the Bluetooth headset; if the control end receives a danger instruction, the process goes to step A2.

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