Audio recording and conversion method for bluetooth earphone

Abstract

The present application specifically relates to the field of audio recording and conversion. Disclosed is an audio recording and conversion method for a Bluetooth earphone. In the present application, a Bluetooth function of an audio source device is enabled to establish a paired connection to a Bluetooth earphone; subsequently, a recording process is started by means of a "record" button on the earphone, and a system guides a user to select an audio format and confirm recording settings; during recording, a built-in microphone of the earphone collects an audio signal in real time, performs denoising and signal amplification processing on the collected audio signal, and then converts the processed audio signal into a digital signal; a watermark is embedded into the processed digital signal, a watermark evaluation value is calculated, and the watermark evaluation value is used for comparison to verify whether the watermark has been embedded; then, the digital signal is converted into an analog signal, and an audio signal is reconstructed; and finally, the system performs watermark detection on the reconstructed audio signal, and detected watermark information is compared, so as to ensure the integrity and authenticity of audio signal data.

Description

Audio recording and conversion method for Bluetooth earphone

[0001] The present application claims priority to the Chinese patent application No. CN202411279492.2, filed on September 12, 2024, and entitled "Audio recording and conversion method for Bluetooth earphone", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the field of audio recording conversion, in particular to an audio recording and conversion method for Bluetooth earphone. BACKGROUND

[0003] In today's fast-paced digital age, Bluetooth earphones, as representatives of personal audio devices, have penetrated into all aspects of our lives, from daily commuting to sports fitness, to remote office work and online education. Bluetooth earphones have won a wide user base with their convenience, wireless freedom and high sound quality performance; however, with the advancement of technology and the diversification of application scenarios, users' functional needs for Bluetooth earphones have also grown, especially in terms of audio security conversion and management, which has become an important issue to be addressed.

[0004] However, in actual use, the traditional Bluetooth earphone audio recording still has some shortcomings, such as the traditional Bluetooth earphone mainly focuses on the stability of audio transmission and sound quality performance, and there is a significant deficiency in the privacy of converted audio recording data.

[0005] SUMMARY

[0006] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present application provide an audio recording and conversion method for Bluetooth earphone to solve the problems raised in the background art.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] Step A1: turn on the Bluetooth function of the audio source device, pair and connect through Bluetooth; and confirm the recording settings;

[0009] Step A2: during the recording process, the built-in microphone of the Bluetooth earphone collects audio signals in real time, and processes the collected audio signals to obtain digital signals;

[0010] Step A3: embed watermarks in the processed digital signals, and calculate watermark evaluation values according to the embedded watermarks;

[0011] Step A4: convert the digital signals embedded with watermarks into analog signals, and reconstruct the audio signals;

[0012] Step A5: the reconstructed audio signal is detected for watermark, and the detected watermark is compared.

[0013] Preferably, in step A1, after the sound source device is turned on, it is ensured that it is in a "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 Bluetooth setting page of the sound source device, click "Search device" to start scanning nearby Bluetooth devices; in the scanning result, find the name of the connected Bluetooth audio device and click it.

[0014] The user touches the "recording" special button on the Bluetooth headset, and the built-in microphone of the Bluetooth headset is activated to receive sound signals; at the same time, the Bluetooth headset sends a recording start signal to the paired smart device through Bluetooth connection, and the paired smart device receives the recording start signal, and a recording application notification pops up on the screen; the system prompts the user in a friendly interface and clear language: "Recording will start soon, please select the audio format you want;" the user selects the WAV audio format according to the needs in the options provided on the interface, and after selecting the audio format, the system displays the current recording setting overview; the user needs to carefully check these settings to ensure that they meet their own needs; if you need to modify, click the corresponding option to adjust; when the recording settings are determined, the user clicks the "Start recording" button, and the system starts recording according to the set parameters.

[0015] Preferably, in step A2, the collected audio signal is amplified and denoised, and the denoising method is specifically:

[0016] Step B1: the collected audio signal is preprocessed, which includes removing the direct current component and applying a window function at the front end of the signal to reduce noise in the processing;

[0017] Step B2: use fast Fourier transform to convert the time domain signal to frequency domain representation; after obtaining the frequency spectrum, express the frequency spectrum as amplitude spectrum and phase spectrum;

[0018] Step B3: select a paragraph that does not contain useful signals for noise estimation; calculate the spectrum of the noise segment to obtain the amplitude spectrum of the segment;

[0019] In this step, smoothing processing is applied to the spectrum of the noise to obtain a more stable noise model;

[0020] Step B4: perform spectral subtraction on the amplitude spectrum of the original signal to obtain a second amplitude spectrum, and the calculation method of the second amplitude spectrum is specifically:

[0021] 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 a reduction factor for further reducing residual noise; max represents comparing two values and selecting the larger one;

[0022] Step B5: a new spectrum is constructed by combining the denoised amplitude spectrum with the phase spectrum of the original signal, and the calculation method of the new spectrum is specifically:

[0023] Wherein, F(a)0 represents the constructed new spectrum, F(a) represents the second amplitude spectrum obtained after removing noise, eL(a) represents the phase spectrum representing the original noisy signal, and δ(a) represents the phase angle of the a-th frequency component;

[0024] Step B6: the denoised spectrum is converted back to the time domain using the inverse fast Fourier transform to obtain the processed audio signal.

[0025] The method for amplifying the audio signal is specifically:

[0026] Step C1: converting the audio signal after denoising into an electrical signal.

[0027] This electrical signal is usually very weak and can only be recognized by delicate electronic components.

[0028] Step C2: the weak audio signal enters the preamplifier, and the preamplifier increases the intensity of the weak signal to a processable level.

[0029] Step C3: the preamplifier has a gain adjustment function, and the user sets the gain value according to the needs.

[0030] Wherein, the gain refers to the proportion of signal amplification, and reasonable gain setting ensures that the audio signal will not be excessively distorted or introduce noise;

[0031] Step C4: the amplified signal is subjected to subsequent digital signal processing, and the signal is further clarified and various audio effects are applied.

[0032] Preferably, in step A3, after embedding the digital signal with a watermark, the calculation method of the watermark evaluation value watermark stability value is specifically:

[0033] Wd=X(D+I), wherein Wd represents the watermark stability value, X represents the correlation coefficient, I represents the frequency domain watermark evaluation value, and D represents the first capacity value.

[0034] The calculation method of the watermark sampling ratio is specifically:

[0035] Wherein, Z represents the watermark sampling ratio, q(b) represents the sampling value of the host audio signal before the watermark is embedded, q0(b) represents the sampling value of the host audio signal after the watermark is embedded, and T represents the total number of samples;

[0036] The calculation method of the watermark evaluation value is specifically:

[0037] Wherein, Q represents the watermark evaluation value, X represents the correlation coefficient, Z represents the watermark sampling ratio, and Wd represents the watermark stability value.

[0038] Preferably, in the step A4, a DAC device is selected, the reference voltage, output range, and resolution of the DAC are set, and the converted digital signal is extracted; the prepared digital signal value is written into the data input register of the DAC, and the conversion is waited to start; according to the design of the DAC, the conversion is triggered by an external signal, and in the conversion process, the clock signal of the DAC is ensured to be correct and accurate, so that the digital signal can be converted as planned.

[0039] After the conversion of the DAC is completed, a stable analog signal is obtained at the output end; this process is affected by the settling time of the DAC; the output analog signal is smoothed by a filter to obtain a more natural audio waveform; after the DAC and the filter, the signal is converted into a continuous analog waveform, and the continuous analog waveform is the reconstructed audio signal.

[0040] Preferably, in the step A5, the watermark information is extracted from the reconstructed audio signal, and the extracted watermark information is calculated to obtain a watermark similarity value; the calculation method of the watermark similarity value is specifically:

[0041] Wherein, V represents the watermark similarity value, S represents the sample point, M represents the number of frames of the audio, and N(e, f) represents the amplitude value of the e-th frame and the f-th frequency point.

[0042] According to 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, and the audio signal is stored in the built-in memory of the Bluetooth earphone; if the calculated watermark similarity value is not equal to the preset watermark similarity value threshold, a danger instruction is output, and the step A2 is turned to.

[0043] The technical effects and advantages of the present application are:

[0044] The application provides an audio recording and conversion method for a Bluetooth headset. The application supports direct recording operation and audio format selection on the Bluetooth headset through Bluetooth pairing connection of a sound source device. The system automatically processes and embeds a watermark into the recorded audio signal, 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 provides a natural and real auditory experience for users. BRIEF DESCRIPTION OF DRAWINGS

[0045] Fig. 1 is a flowchart of the method of the application. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the application.

[0047] Please refer to Fig. 1. The application provides an audio recording and conversion method for a Bluetooth headset, including the following steps:

[0048] Step A1: Turn on the Bluetooth function of the sound source device, perform pairing connection through Bluetooth, and confirm the recording settings.

[0049] In step A1, after the sound source device turns on the Bluetooth, it is ensured to be in a "discoverable" state, so that the nearby Bluetooth device can search it. For the Bluetooth audio device to be connected, enter the pairing mode according to the instructions in the instruction book. In the Bluetooth setting page of the sound source device, click "Search device" to let the device start scanning the nearby Bluetooth devices. In the scanning result, find the name of the connected Bluetooth audio device and click it. At this time, the sound source device and the Bluetooth audio device are connected.

[0050] The user taps the "recording" special button on the Bluetooth headset, the Bluetooth headset built-in microphone is activated immediately, ready to receive sound signals; at the same time, the Bluetooth headset sends a recording start signal to the smart device paired with it through Bluetooth connection, after the paired smart device receives the recording start signal, the recording application notification pops up on the screen immediately; the system prompts the user in a friendly interface and clear language: "recording will start soon, please select the audio format you want;" the user selects the WAV audio format according to the needs in the options provided on the interface, after selecting the audio format, the system displays the current recording setting overview; the user needs to check these settings carefully to ensure that they meet their own needs; if you need to modify, click the corresponding option to adjust; when the recording setting is determined, the user clicks the "start recording" button, and the system starts recording according to the set parameters.

[0051] 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.

[0052] Step A2: In 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;

[0053] In the step A2, the collected audio signals are amplified and denoised, and the denoising method is specifically as follows:

[0054] Step B1: The collected audio signals are preprocessed, which includes removing the direct current component and applying a window function at the front end of the signal to reduce the noise impact in the processing;

[0055] Step B2: Use fast Fourier transform to convert the time domain signal to frequency domain representation; after obtaining the frequency spectrum, express the frequency spectrum as amplitude spectrum and phase spectrum;

[0056] Step B3: Select a paragraph 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;

[0057] In this step, smoothing processing is applied to the frequency spectrum of the noise to obtain a more stable noise model;

[0058] Step B4: Perform spectral subtraction on the amplitude spectrum of the original signal to obtain a second amplitude spectrum, and the calculation method of the second amplitude spectrum is specifically as follows:

[0059] Wherein, F(a) represents the second amplitude spectrum obtained by removing noise, G(a) represents the estimated noise amplitude spectrum; H(a) represents the amplitude spectrum of the noise signal, β represents a subtraction factor for further reducing residual noise; max represents comparing two values and selecting the larger one;

[0060] 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:

[0061] Where F(a)0 represents the constructed new spectrum, F(a) represents the second amplitude spectrum obtained after removing noise, eL(a) represents the phase spectrum representing the original noisy signal, and δ(a) represents the phase angle of the a-th frequency component.

[0062] Step B6: The denoised spectrum is converted back to the time domain using the inverse fast Fourier transform to obtain the processed audio signal.

[0063] The denoised audio is subjected to sound detection, and the audio confirmation value is used to determine whether the denoised audio has sound. The calculation method of the audio confirmation value is as follows:

[0064] Where R represents the audio confirmation value, N(e, f) represents the amplitude value of the f-th frequency point of the e-th frame, H represents the total number of audio frames, p represents the spectrum window length, f max represents the upper limit of the frequency point amplitude value, and f min represents the lower limit of the frequency point amplitude value.

[0065] The preprocessed audio signal to be measured is subjected to framing and windowing, with a frame length of 32 milliseconds, a frame shift of 16 milliseconds, and Hamming windowing. Then, a Fourier transform with a length of 8192 points is performed to obtain the audio signal to be measured.

[0066] Framing and windowing: The audio signal is divided 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.

[0067] Hamming windowing: To reduce spectral leakage, each frame is multiplied by a Hamming window function. The Hamming window is a commonly used window function that can provide good frequency resolution and low sidelobe level in the frequency domain.

[0068] Fourier transform: A 8192-point Fourier transform is performed on each windowed frame, which converts the audio signal from the time domain to the frequency domain and obtains the frequency spectrum signal.

[0069] The calculation method of N(e, f) is as follows:

[0070] Where N(e, f) represents the amplitude value of the f-th frequency point of the e-th frame, T represents the harmonic value, and p represents the spectrum window length.

[0071] The calculated audio confirmation value is compared with a preset audio confirmation value threshold, if the calculated audio confirmation value is greater than the preset audio confirmation value threshold, it is determined that the audio has sound; if the calculated audio confirmation value is less than the preset audio confirmation value threshold, it is determined that the audio has no sound;

[0072] The method for signal amplification of the audio signal is specifically:

[0073] Step C1: converting the de-noised audio signal into an electrical signal.

[0074] This electrical signal is usually very weak and can only be recognized by delicate electronic components.

[0075] Step C2: the weak audio signal enters a preamplifier, which increases the intensity of the weak signal to a processable level.

[0076] Step C3: the preamplifier has a gain adjustment function, and the user sets the gain value according to the needs.

[0077] Wherein, the gain refers to the proportion of signal amplification, and reasonable gain setting ensures that the audio signal will not be excessively distorted or introduce noise;

[0078] Step C4: the amplified signal is subjected to subsequent digital signal processing, and the signal is further clarified and various audio effects are applied.

[0079] Step A3: embedding the processed digital signal with a watermark, and calculating a watermark evaluation value according to the embedded watermark;

[0080] In step A3, after embedding the digital signal with a watermark, the watermark evaluation value is calculated, and the calculation method of the first capacity value is specifically:

[0081] 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;

[0082] The calculation method of the frequency domain watermark evaluation value is specifically:

[0083] Wherein, I represents the frequency domain watermark evaluation value, a represents the sampling frequency of the audio signal, P represents the number of embedded watermark bits 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.

[0084] The calculation method of the correlation coefficient is specifically:

[0085] Wherein, X represents the correlation coefficient, t represents the bit value of the original watermark, and t0 represents the detected watermark bit value.

[0086] The calculation method of the watermark stability value is specifically:

[0087] Wd=X(D+I), wherein Wd represents the watermark stability value, X represents the correlation coefficient, I represents the frequency domain watermark evaluation value, and D represents the first capacity value;

[0088] The calculation method of the watermark sampling ratio is specifically:

[0089] wherein 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;

[0090] The calculation method of the watermark evaluation value is specifically:

[0091] wherein Q represents the watermark evaluation value, X represents the correlation coefficient, Z represents the watermark sampling ratio, and Wd represents the watermark stability value;

[0092] The calculated watermark evaluation value is compared with the preset watermark evaluation threshold value, if the calculated watermark evaluation value is greater than the preset watermark evaluation threshold value, a success instruction is output, and the step A5 is performed; if the calculated watermark evaluation value is less than the preset watermark evaluation threshold value, a failure instruction is output, and the watermark is re-embedded.

[0093] Step A4: converting the digital signal embedded with the watermark into an analog signal, and reconstructing an audio signal;

[0094] In the step A4, a DAC device is selected, the reference voltage, output range and resolution of the DAC are set, and the converted digital signal is extracted; the digital signal value prepared is written into the data input register of the DAC, and the conversion is waited to start; according to the design of the DAC, the conversion is triggered by an external signal, and in the conversion process, the clock signal of the DAC is ensured to be correct and accurate, so that the digital signal can be converted as planned;

[0095] After the conversion of the DAC is completed, a stable analog signal is obtained at the output end; this process is affected by the settling time of the DAC; the output analog signal is smoothed by a filter to obtain a more natural audio waveform, and after the DAC and the filter, the signal is converted into a continuous analog waveform, and the continuous analog waveform is the reconstructed audio signal.

[0096] DAC represents digital-to-analog conversion.

[0097] Step A5: performing watermark detection on the reconstructed audio signal, and comparing the detected watermark.

[0098] In step A5, the watermark information is extracted from the reconstructed audio signal, and the extracted watermark information is calculated to obtain a watermark similarity value, and the calculation method of the watermark similarity value is specifically:

[0099] Wherein, V represents the watermark similarity value, S represents the sample point, M represents the number of frames of the audio, and N(e, f) represents the amplitude value of the e frame and the f frequency point.

[0100] According to 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, and the audio signal is stored in the built-in memory of the Bluetooth earphone; if the calculated watermark similarity value is not equal to the preset watermark similarity value threshold, a danger instruction is output, and the step A2 is turned to.

[0101] It should be noted that the preset value in the present application is determined according to the specific circumstances, that is, the specific value is not limited in the embodiment.

[0102] Finally: the above only for the preferred embodiments of the present application, and not for limiting the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. An audio recording and converting method for Bluetooth earphone, characterized in that, The application relates to a method for recording audio signals and a device thereof. Step A1: turning on the Bluetooth function of a sound source device, pairing and connecting through Bluetooth, and confirming recording settings; Step A2: in the recording process, a built-in microphone of the Bluetooth earphone collects audio signals in real time, and the collected audio signals are processed to obtain digital signals; Step A3: embedding the processed digital signals with watermarks, and calculating a watermark evaluation value according to the embedded watermarks; Step A4: converting the digital signals embedded with the watermarks into analog signals, and reconstructing the audio signals; Step A5: detecting the reconstructed audio signals with watermarks, and judging the detected watermarks.

2. The audio recording and converting method for Bluetooth earphone according to claim 1, characterized in that: In step A2, the collected audio signals are subjected to signal amplification and denoising processing; the denoising processing method is specifically as follows: Step B1: pre-processing the collected audio signals, which includes removing direct current components and applying a window function at the front end of the signal to reduce the noise influence in processing; Step B2: converting the time domain signals into frequency domain representations by using fast Fourier transform; after obtaining the frequency spectrum, the frequency spectrum is represented as an amplitude spectrum and a phase spectrum; Step B3: selecting a paragraph not containing useful signals for noise estimation; calculating the frequency spectrum of the noise paragraph to obtain the amplitude spectrum of the paragraph; Step B4: performing spectral subtraction processing on the amplitude spectrum of the original signal to obtain a second amplitude spectrum, and the calculation method of the second amplitude spectrum is specifically as follows: Wherein, F(a) represents the second amplitude spectrum obtained after removing the noise, G(a) represents the estimated noise amplitude spectrum, H(a) represents the amplitude spectrum of the noise signal, and beta represents a subtraction factor for further reducing residual noise; max represents comparing two values and selecting the larger one; Step B5: combining the amplitude spectrum after denoising with the phase spectrum of the original signal to construct a new frequency spectrum, and the calculation method of the new frequency spectrum is specifically as follows: Wherein, F(a)0 represents the constructed new frequency spectrum, F(a) represents the second amplitude spectrum obtained after removing the noise, eL(a) represents the phase spectrum of the original noisy signal, and delta(a) represents the phase angle of the a-th frequency component; Step B6: converting the denoised frequency spectrum back to the time domain by using inverse fast Fourier transform to obtain the processed audio signal.

3. The method of claim 2, wherein the method further comprises: The audio after denoising is subjected to sound detection, and whether the audio after denoising has sound is judged through an audio confirmation value; the calculation method of the audio confirmation value is specifically as follows: wherein R represents an audio confirmation value, N(e,f) represents an e-th frame f-th frequency point amplitude value, H represents a total number of audio frames, p represents a spectrum window length, f max represents an upper limit of the frequency point amplitude value, f min represents a lower limit of the frequency point amplitude value; The calculation method of N(e, f) is specifically as follows: Wherein, N(e, f) represents the amplitude value of the f-th frequency point of the e-th frame, T represents a harmonic value, and rho represents a frequency spectrum window length; 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.

4. The method of claim 1, wherein the method further comprises: In step A3, after the digital signals are embedded with watermarks, the first capacity value is calculated, and the calculation method of the first capacity value is specifically as follows: Wherein, D represents the first capacity value, E represents the bandwidth of an audio carrier signal, J represents a watermark efficiency, and K represents an attack power; The calculation method of the frequency domain watermark evaluation value is specifically as follows: Wherein, I represents the frequency domain watermark evaluation value, a represents the sampling frequency of the audio signal, P represents the number of embedded watermark bits 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 of audio recording and converting for Bluetooth headset according to claim 4, wherein: The calculation method of the watermark stability value is specifically: Wd=X(D+I), wherein Wd represents the watermark stability value, X represents the correlation coefficient, I represents the frequency domain watermark evaluation value, and D represents the first capacity value. The calculation method of the watermark sampling ratio is specifically: Wherein, Z represents the watermark sampling ratio, q(b) represents the sampling value of the host audio signal before the watermark is embedded, q0(b) represents the sampling value of the host audio signal after the watermark is embedded, and T represents the total number of samples.

6. The audio recording and converting method for Bluetooth earphone according to claim 4 or 5, characterized in that: The calculation method of the watermark evaluation value is specifically: Wherein, Q represents the watermark evaluation value, X represents the correlation coefficient, Z represents the watermark sampling ratio, and Wd represents the watermark stability value.

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

8. The method of audio recording and converting for Bluetooth headset according to claim 1, wherein: In the step A5, the watermark information is extracted from the reconstructed audio signal, and the extracted watermark information is calculated to obtain a watermark similarity value. The calculation method of the watermark similarity value is specifically: Wherein, 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 e-th frame and the f-th frequency point; According to 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; if the calculated watermark similarity value is not equal to the preset watermark similarity value threshold, a danger instruction is output.

9. The method of claim 8, wherein the method further comprises: When the control end receives the safety instruction, the audio signal is stored in the built-in memory of the Bluetooth earphone; if the control end receives the danger instruction, the step A2 is turned to.

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