Audio signal frequency modulation method and apparatus

Abstract

This disclosure presents an audio signal frequency modulation method and apparatus. The specific implementation of the method includes: dividing the audio data to be frequency-modulated into frames to obtain an audio frame sequence; transforming the audio frame sequence from the time domain to the frequency domain to obtain a first frequency domain frame sequence; correcting the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain a second frequency domain frame sequence; adjusting the phase angle of each frequency domain frame in the second frequency domain frame sequence according to a predetermined modulation coefficient to obtain a third frequency domain frame sequence; transforming the third frequency domain frame sequence from the frequency domain to the time domain to obtain a time domain frame sequence; and synthesizing a time domain signal based on the time domain frame sequence. This implementation provides an audio signal frequency modulation and conversion method to meet the needs of rapidly changing modulation and conversion scenarios, and can quickly obtain the corresponding audio modulation signal, which has good continuity and high sound quality.

Description

Technical Field

[0001] The embodiments disclosed herein relate to the field of audio processing technology, and more specifically to an audio signal frequency modulation method and apparatus. Background Technology

[0002] Audio modulation and frequency conversion technology can increase or decrease the frequency components of an audio signal to achieve different purposes, such as suppressing feedback, voice alteration, pitch shifting, and improving the auditory experience for hearing aid users. Currently, there are two main methods for implementing audio signal frequency modulation and frequency conversion: one is through analog circuits, and the other is through audio digital signal processing.

[0003] Devices implemented using analog circuits, such as analog mixing consoles and frequency shifters, have disadvantages such as high cost, large size, slow iteration, and difficulty in porting.

[0004] Audio modulation and frequency conversion technologies such as digital mixing consoles and most audio effects processing software on the market that run on PCs (Personal Computers) cannot adapt to application scenarios with real-time and high-frequency changes. They have serious defects such as severe frame drops and pop sounds, and can no longer meet application requirements. Summary of the Invention

[0005] To address the issues of severe frame loss and pop-up sounds in audio signals during real-time and high-frequency changing application scenarios, an audio signal frequency modulation method and device are proposed.

[0006] In a first aspect, embodiments of this disclosure provide an audio signal frequency modulation method, comprising: dividing audio data to be frequency modulated into frames to obtain an audio frame sequence; transforming the audio frame sequence from the time domain to the frequency domain to obtain a first frequency domain frame sequence; correcting the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain a second frequency domain frame sequence; adjusting the phase angle of each frequency domain frame in the second frequency domain frame sequence according to a predetermined modulation coefficient to obtain a third frequency domain frame sequence; transforming the third frequency domain frame sequence from the frequency domain to the time domain to obtain a time domain frame sequence; and synthesizing a time domain signal based on the time domain frame sequence.

[0007] In some embodiments, dividing the audio data to be frequency-modulated into frames to obtain an audio frame sequence includes: dividing the audio data to be frequency-modulated into frames; and performing windowing processing on the framed audio data to obtain an audio frame sequence.

[0008] In some embodiments, the transformation from the time domain to the frequency domain is a Fast Fourier Transform, and the transformation from the frequency domain to the time domain is an Inverse Fast Fourier Transform.

[0009] In some embodiments, correcting the phase angle of each frequency domain frame in the first frequency domain frame sequence includes: calculating the angular frequency of the frequency domain frame based on the phase angle change between two adjacent frequency domain frames in the first frequency domain frame sequence; correcting the angular frequency; and calculating the corrected phase angle of the next frequency domain frame among two adjacent frequency domain frames based on the corrected angular frequency.

[0010] In some embodiments, the method further includes: determining the amplitude of a third frequency domain frame sequence based on the correspondence between frequency and amplitude in the amplitude spectrum of a first frequency domain frame sequence, wherein the amplitude corresponding to the frequency adjusted by the modulation coefficient remains unchanged.

[0011] In some embodiments, the audio data is audio data emitted while the vehicle is in operation; and the method further includes: determining a modulation coefficient based on the vehicle's operating parameters, wherein the operating parameters include at least one of the following: motor speed, internal combustion engine speed, and accelerator pedal opening.

[0012] In some embodiments, determining modulation coefficients based on vehicle operating parameters includes: mapping operating parameters to different levels according to the value range of the operating parameters; calculating a weighted sum of the operating parameter levels, and converting the weighted sum to a predetermined value range as the modulation coefficients.

[0013] In some embodiments, the audio data described above includes simulated sound wave audio data.

[0014] Secondly, embodiments of this disclosure provide an audio signal frequency modulation apparatus, comprising: a framing unit configured to segment audio data to be frequency modulated into frames to obtain an audio frame sequence; a first transformation unit configured to transform the audio frame sequence from the time domain to the frequency domain to obtain a first frequency domain frame sequence; a correction unit configured to correct the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain a second frequency domain frame sequence; an adjustment unit configured to adjust the phase angle of each frequency domain frame in the second frequency domain frame sequence according to a predetermined modulation coefficient to obtain a third frequency domain frame sequence; a second transformation unit configured to transform the third frequency domain frame sequence from the frequency domain to the time domain to obtain a time domain frame sequence; and a synthesis unit configured to synthesize a time domain signal based on the time domain frame sequence.

[0015] In some embodiments, the framing unit is further configured to: framing the audio data to be frequency modulated; and windowing the framed audio data to obtain an audio frame sequence.

[0016] In some embodiments, the transformation from the time domain to the frequency domain is a Fast Fourier Transform, and the transformation from the frequency domain to the time domain is an Inverse Fast Fourier Transform.

[0017] In some embodiments, the correction unit is further configured to: calculate the angular frequency of a frequency domain frame based on the phase angle change between two adjacent frequency domain frames in the first frequency domain frame sequence; correct the angular frequency; and calculate the corrected phase angle of the next frequency domain frame among the two adjacent frequency domain frames based on the corrected angular frequency.

[0018] In some embodiments, the apparatus further includes a mapping unit configured to: determine the amplitude of a third frequency domain frame sequence based on the correspondence between frequency and amplitude in the amplitude spectrum of a first frequency domain frame sequence, wherein the amplitude corresponding to the frequency adjusted by the modulation coefficient remains unchanged.

[0019] In some embodiments, the audio data is audio data emitted while the vehicle is in operation; and the device further includes a determining unit configured to: determine a modulation coefficient based on the vehicle's operating parameters, wherein the operating parameters include at least one of the following: motor speed, internal combustion engine speed, and accelerator pedal opening.

[0020] In some embodiments, the determining unit is further configured to: map the operating condition parameters to different levels according to the value range of the operating condition parameters; calculate the weighted sum of the operating condition parameter levels, and convert the weighted sum to a predetermined value range as the modulation coefficient.

[0021] In some embodiments, the audio data described above includes simulated sound wave audio data.

[0022] Thirdly, embodiments of this disclosure provide a vehicle including: an audio signal modulation device as described in any of the second aspects above; and in-vehicle speakers and / or external speakers.

[0023] In some embodiments, the vehicle includes a plurality of external speakers located at different positions on the exterior body of the vehicle; and the plurality of external speakers are controlled to emit sound according to user needs or simulated sound wave requirements.

[0024] Fourthly, embodiments of this disclosure provide an electronic device, including: one or more processors; and a storage device having one or more computer programs stored thereon, wherein when the one or more computer programs are executed by the one or more processors, the one or more processors implement the method as described in any one of the first aspects.

[0025] Fifthly, embodiments of this disclosure provide a computer-readable medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method as described in any one of the first aspects.

[0026] In a sixth aspect, embodiments of this disclosure provide a computer program product including a computer program that, when executed by a processor, implements the method as described in any one of the first aspects.

[0027] According to the audio signal frequency modulation method of this disclosure, after dividing the audio data to be frequency-modulated into frames to obtain an audio frame sequence, a transformation from the time domain to the frequency domain is first performed. Then, based on the obtained frequency domain frame sequence, the phase angle of each frame is corrected and modulated, starting from the phase angle. This achieves real-time dynamic adjustment of the phase angle of each frame to obtain the expected center frequency component, providing a strong guarantee for accurate signal frequency modulation (or frequency conversion). Furthermore, the frequency domain frame sequence obtained after phase angle correction and modulation can be inversely transformed from the frequency domain to the time domain, and a time domain signal is synthesized based on the time domain frame sequence obtained after the inverse transformation, thereby completing the effective frequency modulation of the audio signal. Thus, this audio signal frequency modulation scheme can meet the needs of rapidly changing modulation and frequency conversion scenarios, quickly obtain the corresponding audio modulation signal, and ensure that the frequency-modulated audio signal has continuity, real-time performance, and high definition, without discontinuities, pop sounds, noise, or other sound quality defects, thereby improving the user's audio quality experience.

[0028] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0029] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0030] Figure 1 This is an exemplary system architecture diagram to which one embodiment of this disclosure can be applied;

[0031] Figure 2 This is a flowchart of an embodiment of the audio signal frequency modulation method according to the present disclosure;

[0032] Figure 3 This is a schematic diagram of an application scenario of the audio signal frequency modulation method according to this disclosure;

[0033] Figure 4 This is a flowchart of yet another embodiment of the audio signal frequency modulation method according to the present disclosure;

[0034] Figure 5 This is a schematic diagram of the structure of an audio signal frequency modulation device according to an embodiment of the present disclosure;

[0035] Figure 6 This is a schematic diagram of the structure of a computer system suitable for implementing embodiments of the present disclosure. Detailed Implementation

[0036] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0039] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0040] Audio modulation and frequency conversion technology can increase or decrease the frequency components of an audio signal to achieve different purposes, such as suppressing feedback, voice alteration, pitch shifting, and improving the auditory experience for hearing aid users. Currently, there are two main methods for implementing audio signal frequency modulation and frequency conversion: one is through analog circuits, and the other is through audio digital signal processing.

[0041] Among them, the frequency modulation and conversion circuits in devices that use analog circuits, such as analog mixing consoles and frequency shifters, are relatively complex. Audio signals need to undergo amplification, modulation, filtering, demodulation, and other processing, and the circuit design / debugging is relatively complex, with high precision requirements for components. It has disadvantages such as complex design, difficult calibration, high cost, large size, slow iteration, and difficulty in porting.

[0042] Audio modulation and frequency conversion technologies, such as digital mixing consoles and PC-based audio effects processing software, utilize digital audio signal processing techniques. The audio signal processing flow involves converting analog signals into digital signals through sampling, quantization, and encoding. Then, based on digital audio signal processing methods, audio signal modulation and frequency conversion are achieved in the frequency or time domain to achieve the desired audio modulation and frequency conversion. Specifically, before the device or software runs, relevant parameters are pre-set according to the modulation and frequency conversion requirements, or these parameters are set during operation. Once set, the parameters remain unchanged for a period of time, during which the desired audio signal is acquired. After a period of time, if the requirements change, the parameters are readjusted, and then remain unchanged for another period. Subsequently, the audio modulation and frequency conversion signal corresponding to the new parameters is generated.

[0043] However, for application scenarios that require real-time and high-frequency changes in audio modulation and frequency conversion signals (such as scenarios where vehicle speed changes rapidly and frequently during vehicle operation), i.e., scenarios that require rapid and real-time changes in modulation and frequency conversion parameters and the ability to quickly obtain the corresponding audio modulation signal, the existing digital processing methods for audio modulation and frequency conversion can no longer meet the application requirements. The processed audio signal will have serious defects such as frame loss and pop sounds.

[0044] Therefore, there is a need for an audio signal modulation scheme that can meet the needs of modulation and frequency conversion scenarios with rapid real-time frequency changes, quickly obtain the corresponding audio modulation signal, and ensure that the audio signal has good continuity and high sound quality.

[0045] Figure 1 An exemplary system architecture is shown that can be applied to embodiments of the audio signal modulation method or audio signal modulation apparatus of this disclosure.

[0046] like Figure 1 The system architecture shown may include: a vehicle information acquisition module, an MCU (Microcontroller Unit), a SoC (System on Chip), memory, external speakers, and internal speakers. Among them:

[0047] The vehicle information acquisition module is used to collect vehicle information, including but not limited to vehicle speed, motor speed, internal combustion engine speed, and accelerator pedal opening. The vehicle information acquisition module sends this information to the MCU via the CAN bus. The MCU receives the vehicle information and determines whether audio signal modulation is needed based on this information. For example, if the vehicle speed exceeds a predetermined threshold, the engine audio needs to be modulated; if reverse gear is detected, the pedestrian warning audio needs to be modulated. The calculation method for the modulation coefficients required during the modulation process can be found in process 400 below.

[0048] The storage device is used to store engine audio files and pedestrian warning audio files, etc.

[0049] The SoC (System-on-Chips) modulates the audio signal from the engine audio file according to MCU (Microcontroller Unit) instructions and sends the modulated audio signal to the in-vehicle speakers for playback. It can also modulate the audio signal from the pedestrian warning audio file according to MCU instructions and send the modulated audio signal to the external speakers for playback. Audio signal modulation can be performed using the method shown in flowchart 200 below.

[0050] In-vehicle speakers, located inside the vehicle, receive audio signals sent by the SoC (System-on-a-Chip) and play them, thus compensating for the lack of engine sound in new energy vehicles where electric motors replace internal combustion engines. In-vehicle speakers can be thin-film piezoelectric speakers, traditional speakers, etc.

[0051] External speakers, located outside the vehicle, receive audio signals sent by the SoC (System-on-a-Chip) and play them to simulate engine sounds to alert pedestrians of approaching vehicles, ensuring pedestrian safety. External speakers can be thin-film piezoelectric vibrator speakers, traditional speakers, etc.

[0052] The overall workflow is as follows:

[0053] S1. The vehicle information collection module can collect vehicle information in real time, including but not limited to vehicle speed, motor speed, internal combustion engine speed, accelerator pedal opening, etc.

[0054] S2. The MCU determines whether to send an audio modulation command to the SoC based on the vehicle information.

[0055] S3: The SoC retrieves the corresponding audio file from the memory according to the instructions of the MCU, performs audio modulation, and then sends the modulated signal to the in-vehicle speakers and the out-of-vehicle speakers.

[0056] To improve the safety of new energy vehicles and enhance the driving experience, the application scenarios of the audio signal frequency modulation method provided in this disclosure include, but are not limited to:

[0057] (1) In-vehicle sound: In-vehicle speakers are deployed in the vehicle cabin. Based on the driver's operation and vehicle driving conditions (including but not limited to vehicle speed, motor speed, internal combustion engine speed, and accelerator pedal opening), the modulation coefficient is determined. Then, based on the modulation coefficient, the engine sound is synthesized in real time using the method shown in process 200 and played through the in-vehicle speakers. This is used to compensate for the lack of engine sound in new energy vehicles after the internal combustion engine is replaced by an electric motor. Of course, it can also be used to enhance the sound layering of traditional fuel vehicle engines. Through in-vehicle sound, the driving experience can be improved, the driving immersion can be enhanced, and fatigue driving and dangerous driving can be effectively reduced. In-vehicle speakers can be deployed in the interior panels or flexible fabrics of the vehicle, distributed in the seats, dashboard, door panels, etc.

[0058] (2) External Engine Sound: External speakers are deployed on the exterior of the vehicle. Based on driver operation and vehicle driving conditions (including but not limited to vehicle speed, motor speed, internal combustion engine speed, and accelerator pedal opening), modulation coefficients are determined. Then, based on the modulation coefficients, the engine sound is synthesized in real time using the method shown in process 200 and played through the external speakers. This is used by new energy vehicles to simulate the engine sound of traditional fuel vehicles. The external speakers can be deployed in the door panels, headlights, front and rear bumpers, or mounted on the vehicle chassis. When the external speakers use thin-film piezoelectric vibrators, the piezoelectric vibrator plates are deployed at different locations on the exterior of the vehicle. The sound output of the external speakers at different locations can be controlled according to user needs or the desired simulated engine sound.

[0059] (3) Low-speed driving warning sound: Since the sound of new energy vehicles is too quiet when driving at low speed, pedestrians often cannot notice the passing of the vehicle, which poses a certain safety hazard. Therefore, it is necessary to determine the modulation coefficient based on the driver's operation and the vehicle's driving conditions (including but not limited to vehicle speed, motor speed, internal combustion engine speed, and accelerator pedal opening), and then use the method shown in process 200 based on the modulation coefficient to simulate the engine sound to alert pedestrians that a vehicle is passing by.

[0060] (4) Simulation environments such as games: Since the engine sound synthesis principle in racing games is the same as that of real vehicles, the audio signal frequency modulation method disclosed herein is also applicable to simulation environments such as games.

[0061] Continue to refer to Figure 2 The diagram illustrates a flow 200 of an embodiment of an audio signal frequency modulation method according to the present disclosure. The audio signal frequency modulation method may include the following steps:

[0062] Step 201: Divide the audio data to be frequency-modulated into frames to obtain an audio frame sequence.

[0063] In this embodiment, the execution subject of the audio signal frequency modulation method (e.g., Figure 1 The SoC (System-on-a-Chip) in this disclosure can acquire the audio data to be regulated via wired or wireless connection. The audio data (also referred to as audio signal data) to be processed in this disclosure can be audio signal data acquired by devices such as microphones and obtained through analog-to-digital conversion, or audio signal data obtained from audio files read from memory. The source of the audio signal data will not be discussed in detail here.

[0064] Furthermore, to ensure the real-time performance of audio signal processing and avoid the accumulation and averaging of all changes in the signal spectrum when processing the entire signal, resulting in poor instantaneous characteristics, the aforementioned execution entity needs to perform frame-based processing on the audio data to be frequency-modulated, dividing the signal into small segments, each segment being called a frame, thus obtaining an audio frame sequence. In this embodiment of the disclosure, considering that audio signals in real life are usually aperiodic, by performing frame-based processing on the audio data to be frequency-modulated, each frame in the audio frame sequence can be regarded as a signal with a short-term invariant period.

[0065] Step 202: Transform the audio frame sequence from the time domain to the frequency domain to obtain the first frequency domain frame sequence.

[0066] In this embodiment, time-domain to frequency-domain conversion is the process of converting a time-domain signal to a frequency-domain signal. Converting the input of a time-domain signal to the output of a frequency-domain signal allows for a better understanding of the original signal and assists in corresponding analysis and calculations. The time-domain to frequency-domain conversion can be achieved using any of the following methods: Discrete Fourier Transform (DFT), Fast Fourier Transform (FFT), Nyquist Transform, Wavelet Transform, or Rice Transform. This step aims to, based on the audio data frame-by-frame processing in step 201 above, use, for example, Fourier Transform at the granularity of each frame in the audio frame sequence to obtain frequency-domain related information, and simultaneously calculate the amplitude and phase angle corresponding to each frame in the first frequency-domain frame sequence.

[0067] Step 203: Correct the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain the second frequency domain frame sequence.

[0068] In the embodiments of this disclosure, in order to make the subsequent frequency modulation more accurate, it is necessary to correct the phase angle of each frame in the first frequency domain frame sequence obtained in the above steps, so as to realize the real-time dynamic adjustment of the phase of each frame. In particular, when the audio data to be frequency-modulated is not framed according to the signal period, each frequency domain frame will have a certain phase shift. In this case, the phase angle correction in this embodiment is beneficial to accurately obtain the corresponding center frequency component, thereby ensuring the effect of audio signal frequency modulation.

[0069] In this embodiment, phase correction refers to adjusting the phase of the audio signal so that the original audio signal can be more accurately reproduced during playback or recording. Phase refers to the vibration state of a sound wave over a certain period of time, which determines the position, direction, and spatial sense of the sound. Audio phase correction can improve sound quality, enhance the accuracy and stereoscopic effect of audio, and make music more realistic.

[0070] During audio signal playback and recording, various factors, such as transmission delay between the audio source and monitoring equipment, and the characteristics of the transmission medium, can cause phase distortion in the audio signal. Phase distortion leads to phase differences in the audio signal during playback or recording, thus affecting the quality of the audio signal. The principle of audio phase correction is to accurately measure the phase difference and then use algorithms or circuitry to correct the phase difference, restoring the phase of the audio signal to its original state.

[0071] In some optional implementations of the embodiments of this disclosure, the phase angle of each frequency domain frame in the first frequency domain frame sequence can be corrected by any of the following phase correction methods to obtain the second frequency domain frame sequence: direct method, digital signal processing (DSP) method, and adaptive method.

[0072] Furthermore, in a specific implementation of this disclosure, an adaptive method can be used for phase correction. For the audio data to be frequency-modulated, multiple frames belonging to the same signal block can be identified. Each frame signal can be transformed into multiple frequency domain components through time-frequency domain transformation. In this step, phase compensation can be performed on all frequency domain components in a frame signal, or only on a portion of the frequency domain components; this embodiment does not limit this. As one possible implementation, for any given frame, phase compensation can be performed on all frequency domain components in the time dimension, updating the phase of all frequency domain components in the current frame, so that the phase of all frequency domain components in this frame is continuous with the corresponding frequency domain components in the previous frame. Additionally, for any given frame, phase compensation can be performed on at least a portion of the frequency domain components based on the original phase of the frequency domain components in the same frame that are different from the original phase of the frequency domain components.

[0073] Step 204: Adjust the phase angle of each frequency domain frame in the second frequency domain frame sequence according to the predetermined modulation coefficient to obtain the third frequency domain frame sequence.

[0074] Step 205: Transform the third frequency domain frame sequence from the frequency domain to the time domain to obtain the time domain frame sequence.

[0075] Step 206: Synthesize time-domain signals based on time-domain frame sequences.

[0076] In this embodiment, real-time modulation and frequency conversion can be performed according to predetermined modulation coefficients, thereby obtaining a precise frequency-modulated audio signal. A time-domain frame sequence can be obtained by inverse calculation based on the modulated third frequency domain frame sequence, and a time-domain signal can be synthesized based on this. The predetermined modulation coefficients can be set according to the specific application scenario of this audio signal frequency modulation method. In some optional implementations of this disclosure, the frequency domain can be converted to the time domain using any of the following methods: Inverse Fourier Transform (IFT), Inverse Discrete Fourier Transform (IDFT), Inverse Fast Fourier Transform (IFFT), Inverse Laplace Transform, etc.

[0077] According to the audio signal frequency modulation method of this disclosure, after dividing the audio data to be frequency-modulated into frames to obtain an audio frame sequence, a transformation from the time domain to the frequency domain is first performed. Then, based on the obtained frequency domain frame sequence, the phase angle of each frame is corrected and modulated, starting from the phase angle. This achieves real-time dynamic adjustment of the phase angle of each frame to obtain the expected center frequency component, providing a strong guarantee for accurate signal frequency modulation (or frequency conversion). Furthermore, the frequency domain frame sequence obtained after phase angle correction and modulation can be inversely transformed from the frequency domain to the time domain, and a time domain signal can be synthesized based on the time domain frame sequence obtained by the inverse transformation, thereby completing the effective frequency modulation of the audio signal. Thus, this audio signal frequency modulation scheme can meet the needs of rapidly changing modulation and frequency conversion scenarios, quickly obtain the corresponding audio modulation signal, and ensure that the frequency-modulated audio signal has continuity, real-time performance, and high definition, without discontinuities, pop sounds, noise, or other sound quality defects, thereby improving the user's audio quality experience.

[0078] In related technologies, according to the conventional theory of digital signal processing, audio signals can be synthesized from sinusoidal signals. In the Fourier transform of sinusoidal signals, there is the concept of frequency resolution. Frequency resolution refers to the smallest interval that can distinguish two adjacent frequency components in spectral analysis. It can be described as the ability of the Fourier transform to keep two very close spectral peaks in a signal separate. Frequency resolution Δf = fs / N, where fs is the sampling frequency and N is the number of sampling points. By performing discrete Fourier transforms on sinusoidal signals containing multiple known frequencies after framing them multiple times, it can be seen that if the interval between these known frequencies is greater than the frequency resolution, the known frequency components can be accurately calculated. However, if the interval between two adjacent frequencies is less than the frequency resolution, the calculation results will be biased, causing distortion. Ideally, the frequency intervals of audio signals will always be greater than the frequency resolution, and the audio signal will always accurately obtain the corresponding center frequency component. However, for audio signals collected from real life, the frequency components are more complex. Over time, during real-time modulation and frequency conversion, the center frequency will change in real time. Therefore, these dense audio signals cannot always satisfy the requirement of being greater than the frequency resolution. In view of this situation, the audio signal frequency modulation method of the present disclosure can meet the modulation and frequency conversion scenarios with rapid real-time frequency changes, and can quickly obtain the corresponding audio modulation signal, while ensuring that the audio signal has good continuity and high sound quality.

[0079] In the above Figure 2 Based on the corresponding embodiments described above, in some optional implementations of the embodiments of this disclosure, the audio data can be audio data emitted during vehicle operation. Further, the audio data can include, but is not limited to, simulated sound wave audio data. That is, the audio signal frequency modulation method of this disclosure can be applied to the synthesis of sound waves in electric vehicles. The simulated sound wave audio data includes in-vehicle simulated sound wave audio data and / or external simulated sound wave audio data. Further, the external simulated sound wave audio data can include low-speed driving warning audio data. For example, the low-speed driving warning audio data can be emitted by the aforementioned new energy vehicle (such as an electric vehicle) when its current driving speed is lower than the minimum speed limit of the current road.

[0080] In the above Figure 2 Based on the above-described corresponding embodiments, in some optional implementations of the embodiments disclosed herein, step 201 can be specifically executed as follows: dividing the audio data to be frequency-modulated into frames; performing windowing processing on the framed audio data to obtain an audio frame sequence.

[0081] In this embodiment, to facilitate subsequent time-domain to frequency-domain transformations (such as FFT) and reduce the probability of spectral leakage, windowing is required on the audio data of each frame obtained after framing. This allows the finite-length signal to be viewed as a local observation of an infinite-length signal, thereby improving the accuracy of frequency domain analysis. In some optional implementations of this disclosure, windowing of the framed audio data can employ one of the following window functions: Hamming window or Kaiser window (an adjustable window function based on Bessel functions).

[0082] For example, the length of each audio data segment obtained after frame segmentation is called the frame length, which can be denoted as wlen. Usually, for smooth signal transition, there is a certain overlap between adjacent frames. The difference between the starting positions of these two adjacent frames is called the frame shift, which can be denoted as inc. The overlapping portion can be called overlap, where overlap = wlen – inc. Further, the windowing formula for each audio data segment can be expressed as: xw[n] = x[n] * w[n], where x[n] is the audio time-domain signal, w[n] is the window function or window function sequence, and xw[n] is the windowed audio time-domain signal. A schematic diagram of audio signal frame segmentation and windowing can be found here. Figure 3 .

[0083] In some optional implementations of this disclosure, the step size of the sliding window is a set percentage of the frame length, ranging from 10% to 90%, for example, 25%, 50%, and 75%. Each step of the sliding window represents a frame, with the sampling points within the window considered as one frame. For each frame, a transformation from the time domain to the frequency domain can be performed using methods such as Fourier transform to obtain the frequency domain components corresponding to each frame signal. For example, the audio signal length is 10 seconds, and the sampling rate is 16000, 44100, or 48000. In this scenario, the minimum number of sampling points in the block data obtained by segmentation is L = 2048 sampling points. The block data is then segmented and windowed, with the selected window length (frame length) being N = 1024 sampling points, and the sliding window step size (i.e., the time domain frame shift) being 256 sampling points.

[0084] In a specific application scenario, by adopting the audio signal frequency modulation method of this embodiment, after converting the signal from the frequency domain to the time domain in the previous step, and then by adding windows and accumulating overlapping frames in sequence, the desired modulated and frequency-converted time domain signal can be finally obtained, and the synthesized sound wave can be played through the external speakers and the internal speakers of the vehicle.

[0085] exist Figure 2Based on the corresponding embodiments, in some optional implementations of the embodiments disclosed herein, the step of correcting the phase angle of each frequency frame in the first frequency frame sequence in step 203 above can be specifically executed as follows: calculating the angular frequency of the frequency frame based on the phase angle change between two adjacent frequency frames in the first frequency frame sequence; correcting the angular frequency; and calculating the corrected phase angle of the next frequency frame in the two adjacent frequency frames based on the corrected angular frequency.

[0086] In this embodiment, considering that the phase change is closely related to the angular frequency, in order to ensure that an accurate new true phase angle can be obtained, the phase angle can be compensated and corrected by correcting the angular frequency, thereby making the subsequent modulation and frequency conversion more accurate.

[0087] In some optional implementations of the embodiments of this disclosure, in order to ensure the reliability and integrity of the audio signal modulation and frequency conversion, the audio signal frequency modulation method in any of the above embodiments may further include: determining the amplitude of the third frequency domain frame sequence according to the correspondence between frequency and amplitude in the amplitude spectrum of the first frequency domain frame sequence, wherein the amplitude corresponding to the frequency after modulation coefficient adjustment remains unchanged.

[0088] In this embodiment, the pre-modulation frequency (i.e., the frequency in the amplitude spectrum of the first frequency domain frame sequence) and its corresponding post-modulation frequency (i.e., the frequency in the amplitude spectrum of the third frequency domain frame sequence) both correspond to the same amplitude. Therefore, by clarifying the correspondence between the pre-modulation frequency and the amplitude, as well as the correspondence between the pre-modulation frequency and the post-modulation frequency, the amplitude corresponding to the post-modulation frequency can be accurately determined, thereby ensuring the consistency of the audio signal content before and after modulation and frequency conversion.

[0089] In a specific example of an embodiment of this disclosure, the audio signal frequency modulation method of this embodiment is specifically described by taking the transformation from the time domain to the frequency domain as a Fast Fourier Transform and the transformation from the frequency domain to the time domain as an Inverse Fast Fourier Transform.

[0090] For periodic sequences of finite length, such as the audio frames in the aforementioned audio frame sequence, the Functional Fourier Transform (FFT) can be used to transform them and obtain frequency domain information, calculating amplitude, phase, etc. The FFT is an efficient algorithm for calculating the Discrete Fourier Transform (DFT). By reducing the computational cost of the DFT, the FFT makes signal processing more efficient. The basic idea of ​​the FFT is to utilize the periodicity and symmetry of the DFT to decompose the DFT calculation process into a series of iterative operations, thereby significantly reducing the computational load and time.

[0091] In this specific example, the Fourier transform formula is shown in Formula 1, and the formulas for calculating the amplitude and phase angle are shown in Formulas 2-1 and 2-2.

[0092]

[0093] Where X(k) is the k-th (frequency index) frequency component in the frequency domain, which can be represented as a complex number (including amplitude and phase); x(n) represents the n-th (time index) component in the time domain, i.e., the discrete input value (or sampling point number) of the n-th sampling point; N is the length of the sequence, i.e., the number of sampling points (the total number of samples in a frame in the time and frequency domains), where k is greater than or equal to 0 and less than N, and n is greater than or equal to 0 and less than N.

[0094] The above X(k) can be expressed as real + j*imag, where real represents the real part of the audio signal and imag represents the imaginary part of the audio signal. Therefore, the calculated result is:

[0095] Amplitude:

[0096] Phase angle: angle = atan2(imag, real), (Formula 2-2)

[0097] Here, atan2 represents the arctangent function. According to formula 3, the phase change between every two frames is used to calculate the angular frequency change of each frame. Then, according to formulas 4 and 5, the angular frequency between each point (i.e., each frequency component) in each frame is calculated and corrected, which is then converted into phase change. Through this calculation, the phase angle can be compensated and corrected, making the subsequent modulation and frequency conversion more accurate.

[0098] D k =phase[n]-phase[n-1]-2πk*inc / win, (Formula 3)

[0099] Where n represents the frame number, D k The angular frequency change at any point in the nth frame is represented by phase[n], phase[n-1] is represented by phase[n-1], inc is represented by the difference between the starting positions of two adjacent frames (also called frame shift), and win is represented by the total number of frequency components of the signal in the nth frame (also called window length).

[0100]

[0101] In the above formula, [] represents rounding to the nearest integer, mainly to ensure that the phase compensation does not exceed the upper and lower boundaries of the phase. D represents the angular frequency deviation after controlling the range of values. k This represents the change in angular frequency at any point in the nth frame before the control value range.

[0102]

[0103] Where pha represents the corrected phase change, inc represents the difference in the starting positions of two adjacent frames (also called frame shift), win represents the total number of frequency components of the signal in the nth frame, and wlen represents the length of each frame. ω represents the angular frequency deviation in Formula 4, and fs represents the sampling frequency.

[0104] In this specific implementation, frequency conversion can be performed in real time based on parameters (such as vehicle speed). These parameters can be used to obtain modulation coefficients, which can then be applied to the corrected phase angle phase = pha * alpha, where alpha is the modulation coefficient and pha is the corrected phase angle. Furthermore, during the modulation and frequency conversion process, the amplitude spectrum of the audio signal expands or contracts in the corresponding direction. That is, the frequency values ​​on the horizontal axis of the amplitude spectrum expand or contract according to the modulation coefficient (also called the scaling factor), and the corresponding amplitude values ​​must match the new frequency values ​​obtained through precise calculation. For example, when it is necessary to expand a frequency component to a higher level or compress it to a lower level, the actual amplitude values ​​corresponding to the frequency values ​​before and after the frequency conversion should not change. For instance, if the original amplitude of 301 Hz is 18 dB, and after compressing and modulating it to a lower level by 1 Hz to obtain a new frequency value of 300 Hz, its amplitude value should also be 18 dB. In this way, the correspondence between the frequencies before and after modulation can be determined according to the modulation coefficient. Furthermore, based on the correspondence between the frequency before modulation and the original amplitude, it can be determined that the amplitude corresponding to the frequency after modulation is also the original amplitude. Furthermore, the frequency after modulation can be correlated with the original amplitude and the new true phase angle, i.e., the corrected phase angle.

[0105] In this specific implementation, further, based on the above modulated frequency domain results, the following inverse transform formula 6 is used for inverse calculation, and after inverse discrete Fourier transform, the time domain signal is obtained. Specifically, only the real part of the signal can be used to synthesize the modulated frequency conversion signal:

[0106]

[0107] In this embodiment, through the above steps, the newly obtained amplitude, frequency, and phase are transformed back to the time domain through a series of calculations to obtain a time-domain frame sequence.

[0108] Further reference Figure 4 This illustrates a flow 400 of another embodiment of an audio signal frequency modulation method. Flow 400 of this audio signal frequency modulation method includes the following steps:

[0109] Step 401: Determine the modulation coefficient based on the vehicle's operating parameters.

[0110] In this embodiment, the vehicle's operating parameters may include: engine speed. This engine speed can be the motor speed of a pure electric vehicle, or the motor speed and internal combustion engine speed of a hybrid vehicle; this embodiment does not limit this.

[0111] As one possible implementation, the vehicle's operating parameters may also include other operating parameters used to indirectly indicate the engine speed, such as the accelerator pedal opening.

[0112] Optionally, when the operating parameter is specifically the engine speed, in response to the change in engine speed caused by the user's driving operation, the modulation coefficient corresponding to the current operating parameter of the vehicle is determined based on the mapping relationship between the engine speed and the modulation coefficient.

[0113] Modulation coefficients are the required expansion or compression ratios used to expand or compress the frequency domain amplitude spectrum of an audio signal without changing the pitch. In this embodiment, by performing operations such as expansion or compression and compensation on the frequency domain amplitude spectrum of the audio signal, and then restoring the target audio to its original length through difference, audio modulation based on user driving operations can be achieved. Since different rotational speeds result in different modulation coefficients, the final target audio will also differ.

[0114] In some optional implementations of this embodiment, determining the modulation coefficient based on the vehicle's operating parameters includes: mapping the operating parameters to different levels according to the value range of the operating parameters; calculating the weighted sum of the operating parameter levels, and converting the weighted sum to a predetermined value range as the modulation coefficient.

[0115] For example, the engine speed can be normalized based on the vehicle's maximum and minimum engine speeds, and the normalized value can be mapped to one of 10 engine speed levels. Similarly, the maximum and minimum accelerator pedal opening values ​​can be normalized, and the normalized value can be mapped to one of 10 accelerator pedal opening levels. The weighted sum of the engine speed level and the accelerator pedal opening level is calculated and then mapped to different intervals of the modulation coefficient. For example, a weighted sum of 8 results in a modulation coefficient of 0.9, and a weighted sum of 6 results in a modulation coefficient of 0.5. The above mapping method is only illustrative; in practice, various methods can be used to obtain suitable modulation coefficients.

[0116] Step 402: Divide the audio data to be frequency-modulated into frames to obtain an audio frame sequence.

[0117] Step 403: Transform the audio frame sequence from the time domain to the frequency domain to obtain the first frequency domain frame sequence.

[0118] Step 404: Correct the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain the second frequency domain frame sequence.

[0119] Step 405: Adjust the phase angle of each frequency domain frame in the second frequency domain frame sequence according to the predetermined modulation coefficient to obtain the third frequency domain frame sequence.

[0120] Step 406: Transform the third frequency domain frame sequence from the frequency domain to the time domain to obtain the time domain frame sequence.

[0121] Step 407: Synthesize time-domain signals based on time-domain frame sequences.

[0122] Steps 402-407 are basically the same as steps 201-206, so they will not be described again.

[0123] Compared to traditional vehicles, electric vehicles have fewer engine cylinders, and in some cases, the traditional engine is directly replaced by an electric motor. Therefore, optimizing the mechanical systems, including the intake and exhaust systems, makes it more difficult to achieve a distinctive engine sound. To maintain the uniqueness of the engine sound, active sound generation technology is one of the most effective methods and is widely used in electric vehicles. Sound wave synthesis is a key component of active sound generation technology. Through sound wave synthesis, audio can be modulated to generate a rich sound spectrum that more closely resembles the sound of a traditional engine. Transient phase compensation in the aforementioned frequency dimensions improves the robustness of the algorithm and enhances the sound quality of the synthesized audio signal.

[0124] Further reference Figure 5 As an implementation of the methods shown in the above figures, this disclosure provides an embodiment of an audio signal frequency modulation device, which is similar to... Figure 2 Corresponding to the method embodiments shown, this device can be specifically applied to various electronic devices.

[0125] like Figure 5 As shown, the audio signal frequency modulation device 500 of this embodiment includes: a framing unit 501, a first transformation unit 502, a correction unit 503, an adjustment unit 504, a second transformation unit 505, and a synthesis unit 506. The framing unit 501 is configured to segment the audio data to be frequency-modulated into frames to obtain an audio frame sequence; the first transformation unit 502 is configured to transform the audio frame sequence from the time domain to the frequency domain to obtain a first frequency domain frame sequence; the correction unit 503 is configured to correct the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain a second frequency domain frame sequence; the adjustment unit 504 is configured to adjust the phase angle of each frequency domain frame in the second frequency domain frame sequence according to a predetermined modulation coefficient to obtain a third frequency domain frame sequence; the second transformation unit 505 is configured to transform the third frequency domain frame sequence from the frequency domain to the time domain to obtain a time domain frame sequence; and the synthesis unit 506 is configured to synthesize a time domain signal based on the time domain frame sequence.

[0126] In this embodiment, the specific processing of the frame segmentation unit 501, the first conversion unit 502, the correction unit 503, the adjustment unit 504, the second conversion unit 505, and the synthesis unit 506 of the audio signal frequency modulation device 500 can be referred to Figure 2 The corresponding steps are 201, 202, 203, 204, 205 and 206 in the embodiment.

[0127] In some optional implementations of this embodiment, the framing unit 501 is further configured to: framing the audio data to be frequency modulated; and windowing the framing audio data to obtain an audio frame sequence.

[0128] In some optional implementations of this embodiment, the transformation from the time domain to the frequency domain is a Fast Fourier Transform, and the transformation from the frequency domain to the time domain is an Inverse Fast Fourier Transform.

[0129] In some optional implementations of this embodiment, the correction unit 503 is further configured to: calculate the angular frequency of a frequency domain frame based on the phase angle change between two adjacent frequency domain frames in the first frequency domain frame sequence; correct the angular frequency; and calculate the corrected phase angle of the next frequency domain frame in the two adjacent frequency domain frames based on the corrected angular frequency.

[0130] In some optional implementations of this embodiment, the apparatus 500 further includes a mapping unit (not shown in the figures), configured to: determine the amplitude of the third frequency domain frame sequence according to the correspondence between frequency and amplitude in the amplitude spectrum of the first frequency domain frame sequence, wherein the amplitude corresponding to the frequency after modulation coefficient adjustment remains unchanged.

[0131] In some optional implementations of this embodiment, the audio data mentioned above is audio data emitted during vehicle operation; and the device 500 further includes a determining unit (not shown in the figures), configured to: determine the modulation coefficient based on the vehicle's operating parameters, wherein the operating parameters include at least one of the following: motor speed, internal combustion engine speed, and accelerator pedal opening.

[0132] In some optional implementations of this embodiment, the determining unit is further configured to: map the operating parameters to different levels according to the value range of the operating parameters; calculate the weighted sum of the operating parameter levels, and convert the weighted sum to a predetermined value range as the modulation coefficient.

[0133] In some optional implementations of this embodiment, the audio data includes simulated sound wave audio data.

[0134] This embodiment exists as a device embodiment corresponding to the above method embodiment. After dividing the audio data to be frequency-modulated into frames to obtain an audio frame sequence, a transformation from the time domain to the frequency domain is first performed. Then, based on the obtained frequency domain frame sequence, the phase angle of each frame is corrected and modulated, starting from the phase angle. This achieves real-time dynamic adjustment of the phase angle of each frame to obtain the expected center frequency component, providing a strong guarantee for accurate signal frequency modulation (or frequency conversion). Furthermore, the frequency domain frame sequence obtained after phase angle correction and modulation can be inversely transformed from the frequency domain to the time domain, and a time domain signal can be synthesized based on the time domain frame sequence obtained after the inverse transformation, thereby completing the effective frequency modulation of the audio signal. Thus, this audio signal frequency modulation scheme can meet the needs of rapidly changing modulation and frequency conversion scenarios, quickly obtain the corresponding audio modulation signal, and ensure that the frequency-modulated audio signal has continuity, real-time performance, and high definition, without discontinuity, popping sounds, noise, or other sound quality defects, thereby improving the user's audio quality experience.

[0135] Furthermore, according to embodiments of this disclosure, a vehicle is also provided: including an audio signal frequency modulation device as shown in the above embodiments; and in-vehicle speakers and / or external speakers. Thus, the vehicle can meet the needs of rapidly changing modulation and frequency conversion scenarios, and can quickly obtain the expected modulated and frequency-converted audio time-domain signal. It can also ensure that the frequency-modulated audio signal has continuity, real-time performance, and high definition, without discontinuities, popping sounds, or noise, and thus the synthesized sound can be played through the external speakers and / or in-vehicle speakers to improve the user's audio experience.

[0136] In some optional implementations of the embodiments of this disclosure, when the vehicle includes external speakers and comprises multiple external speakers disposed at different locations on the exterior body of the vehicle, the multiple external speakers are controlled to emit sound according to user needs or simulated sound wave requirements. This can further enhance the user's audio quality experience.

[0137] It should be noted that the collection, gathering, updating, analysis, processing, use, transmission, and storage of user personal information involved in this disclosed technical solution all comply with relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. Necessary measures are taken to prevent unauthorized access to user personal information data and to safeguard user personal information security, network security, and national security.

[0138] According to embodiments of this disclosure, this disclosure also provides an electronic device, a readable storage medium, and a computer program product.

[0139] An electronic device includes: one or more processors; and a storage device having one or more computer programs stored thereon, wherein when the one or more computer programs are executed by the one or more processors, the one or more processors implement the method shown in process 200 or 400.

[0140] A computer-readable medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method shown in process 200 or 400.

[0141] A computer program product includes a computer program, wherein the computer program, when executed by a processor, is capable of implementing the method shown in process 200 or 400.

[0142] Figure 6 A schematic block diagram of an example electronic device 600 that can be used to implement embodiments of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present disclosure described and / or claimed herein.

[0143] like Figure 6 As shown, the electronic device 600 includes a computing unit 601, which can perform various appropriate actions and processes based on a computer program stored in a read-only memory (ROM) 602 or a computer program loaded from a storage unit 608 into a random access memory (RAM) 603. The RAM 603 may also store various programs and data required for the operation of the electronic device 600. The computing unit 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0144] Multiple components in electronic device 600 are connected to I / O interface 605, including: input unit 606, such as keyboard, mouse, etc.; output unit 607, such as various types of displays, speakers, etc.; storage unit 608, such as disk, optical disk, etc.; and communication unit 609, such as network card, modem, wireless transceiver, etc. Communication unit 609 allows electronic device 600 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0145] The computing unit 601 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 601 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 601 performs the various methods and processes described above, such as road planning methods. For example, in some embodiments, the road planning method may be implemented as a computer software program tangibly contained in a machine-readable medium, such as storage unit 608. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 600 via ROM 602 and / or communication unit 609. When the computer program is loaded into RAM 603 and executed by the computing unit 601, one or more steps of the road planning method described above may be performed. Alternatively, in other embodiments, the computing unit 601 may be configured to perform the road planning method by any other suitable means (e.g., by means of firmware).

[0146] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transferring data and instructions to the storage system, the at least one input device, and the at least one output device.

[0147] The program code used to implement the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0148] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0149] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0150] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as a data server), or computing systems that include middleware components (e.g., an application server), or computing systems that include frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with embodiments of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., a communication network). Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0151] Computer systems can include clients and servers. Clients and servers are generally geographically separated and typically interact via communication networks. Client-server relationships are created by computer programs running on the respective computers and having a client-server relationship with each other. Servers can be servers in distributed systems or servers incorporating blockchain technology. Servers can also be cloud servers, or intelligent cloud computing servers or intelligent cloud hosts with artificial intelligence technology.

[0152] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0153] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for frequency modulation of an audio signal, comprising: The audio data to be frequency-modulated is divided into frames to obtain an audio frame sequence; The audio frame sequence is transformed from the time domain to the frequency domain to obtain the first frequency domain frame sequence; Correct the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain the second frequency domain frame sequence; The phase angle of each frequency domain frame in the second frequency domain frame sequence is adjusted according to the predetermined modulation coefficient to obtain the third frequency domain frame sequence. The third frequency domain frame sequence is transformed from the frequency domain to the time domain to obtain the time domain frame sequence; A time-domain signal is synthesized based on the time-domain frame sequence.

2. The method of claim 1, wherein, The step of dividing the audio data to be frequency-modulated into frames to obtain an audio frame sequence includes: Divide the audio data to be frequency-modulated into frames; The audio data after being segmented into frames is windowed to obtain an audio frame sequence.

3. The method of claim 1, wherein, The transformation from the time domain to the frequency domain is a Fast Fourier Transform, and the transformation from the frequency domain to the time domain is an Inverse Fast Fourier Transform.

4. The method of claim 1, wherein, The step of correcting the phase angle of each frequency domain frame in the first frequency domain frame sequence includes: The angular frequency of the frequency domain frame is calculated based on the phase angle change between two adjacent frequency domain frames in the first frequency domain frame sequence. Correct the angular frequency; The corrected phase angle of the latter frequency domain frame among the two adjacent frequency domain frames is calculated based on the corrected angular frequency.

5. The method of claim 1, wherein, The method further includes: The amplitude of the third frequency domain frame sequence is determined based on the correspondence between frequency and amplitude in the amplitude spectrum of the first frequency domain frame sequence, wherein the amplitude corresponding to the frequency adjusted by the modulation coefficient remains unchanged.

6. The method of claim 1, wherein, The audio data is audio data emitted while the vehicle is in operation; as well as The method further includes: The modulation coefficient is determined based on the vehicle's operating parameters, wherein the operating parameters include at least one of the following: motor speed, internal combustion engine speed, and accelerator pedal opening.

7. The method of claim 6, wherein, Determining the modulation coefficient based on the vehicle's operating parameters includes: The operating parameters are mapped to different levels according to their value range; Calculate the weighted sum of the operating condition parameter levels, and then convert the weighted sum to a predetermined range of values ​​to use as the modulation coefficient.

8. The method of any one of claims 1 to 7, wherein, The audio data includes simulated sound wave audio data.

9. An audio signal frequency modulation device, comprising: The framing unit is configured to divide the audio data to be frequency modulated into frames to obtain an audio frame sequence; The first transformation unit is configured to transform the audio frame sequence from the time domain to the frequency domain to obtain a first frequency domain frame sequence. The correction unit is configured to correct the phase angle of each frequency domain frame in the first frequency domain frame sequence to obtain the second frequency domain frame sequence. The adjustment unit is configured to adjust the phase angle of each frequency domain frame in the second frequency domain frame sequence according to a predetermined modulation coefficient to obtain a third frequency domain frame sequence. The second transformation unit is configured to transform the third frequency domain frame sequence from the frequency domain to the time domain to obtain a time domain frame sequence; The synthesis unit is configured to synthesize a time-domain signal based on the time-domain frame sequence.

10. A vehicle comprising: The audio signal frequency modulation device as described in claim 9; as well as In-vehicle speakers and / or exterior speakers.

11. The vehicle of claim 10, wherein, The vehicle includes a plurality of external speakers located at different positions on the exterior body of the vehicle; as well as Multiple external speakers are controlled to emit sound according to user needs or simulated sound wave requirements.

12. An electronic device, comprising: One or more processors; Storage device, on which one or more computer programs are stored, When the one or more computer programs are executed by the one or more processors, the one or more processors implement the method as described in any one of claims 1-8.

13. A computer readable medium having stored thereon a computer program, wherein, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-8.

Images