An audio optimization system and method for in-car screen projection

Abstract

The present invention discloses an audio optimization system and method for in-car screen projection, which relates to the technical field of audio processing and in-car screen projection, including a screen projection module, an interface judgment module, a function trigger module, a strategy execution module and a user interaction module; the mobile device is connected to the in-car display screen through the screen projection module, and the audio signal is transmitted to the in-car speaker; the interface judgment module detects the number of speakers in the car and the noise level, determines whether to trigger the sound field compensation, and obtains audio information through the microphone interface, and analyzes the sound quality similarity between the car speaker and the mobile device speaker; the function trigger module automatically calls the mobile device speaker to compensate the sound field when the number of speakers is insufficient or the sound quality similarity is low; the adaptive filter and the strategy matching engine adjust the sound frequency and sound quality of the mobile device and the car speaker in real time. The present invention improves the existing in-car sound quality synchronization and sound effect coverage problems, and enhances the clarity and stability of the in-car audio.

Description

Technical Field

[0001] The present invention relates to the technical field of audio processing and in-vehicle screen projection, and in particular to an audio optimization system and method for in-vehicle screen projection. Background Art

[0002] Existing screen projection technology supports displaying the screen of mobile devices (such as mobile phones) on large-screen devices such as car displays through screen projection protocols such as AirPlay, DLNA, and Miracast. Users usually transmit audio or video content to the speakers in the car for playback through screen projection protocols or interconnection protocols. For example, the mobile phone searches for screen projection device information in the local area network by connecting to the Wi-Fi channel of the same local area network, and sends the video address to the car display. After receiving the video address, the display starts playing the video content. However, when the audio is transmitted to the speakers in the car, there is usually a significant loss of sound quality, especially in the case of wireless connection, the audio compression results in poor sound quality, and the sound quality effect of direct playback on the local device cannot be achieved. In addition, when the number of speakers in the car is small, the sound field coverage is incomplete and the user's audio experience is poor. However, the following defects exist in the prior art:

[0003] Audio compression loss: Due to the audio transmission compression caused by wireless connection, the sound quality of the car speaker is far inferior to the local playback of the mobile device.

[0004] Speaker quantity limitation: When there are insufficient speakers in the car, the sound field is not fully covered and an immersive listening experience cannot be provided.

[0005] Difference in sound quality: There is a difference in sound quality between the sounds produced by mobile device speakers and car speakers, and the existing technology has not been able to effectively solve this difference, resulting in difficulties in audio synchronization and fusion.

[0006] These problems seriously affect the user's sound quality experience when using the screen projection function in the car, especially when there are few speakers in the car or the noise environment is poor, it is difficult to obtain satisfactory sound effects. Summary of the invention

[0007] In response to problems such as audio compression loss, speaker quantity limitation, and sound quality differences, the present invention provides an audio optimization system and method for in-car screen projection, which improves the in-car sound quality experience by detecting the number of in-car speakers and the ambient noise level, and triggering the tuning strategy based on the audio similarity threshold. In particular, the present invention introduces an adaptive filter and a strategy matching engine to adjust the sound frequency and sound quality of the mobile device and the car speaker in real time, so that the sound quality of the two can be integrated.

[0008] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0009] The screen projection module is used to transmit the video content of the mobile device to the car display screen through AirPlay, DLNA, Miracast and other protocols, and the audio signal is output through the car speakers. The interface judgment module detects the number and noise level of the speakers in the car to determine whether to trigger the sound field compensation function. When the sound quality similarity value reaches the set threshold, the tuning strategy is executed.

[0010] The adaptive filter adjusts the sound frequency in real time based on the detected frequency difference between the mobile device speaker and the vehicle speaker to ensure the synchronization of audio output. The frequency difference value is calculated by analyzing the differences in different frequency bands through an improved wavelet transform algorithm, and dynamic correction is achieved in combination with the adaptive filter.

[0011] Through the strategy matching engine deployed in the cloud, a personalized tuning strategy is generated based on the noise level and number of speakers in the car, and sent to the car system and mobile devices. Users can also manually adjust the sound field compensation mode, sound quality optimization progress, and personalized audio parameter configuration through the interactive interface.

[0012] Speaker quantity threshold: The system default speaker quantity threshold is 4. When the number of speakers in the car is less than or equal to this threshold, the system automatically triggers the sound field compensation function.

[0013] Sound quality similarity threshold: The sound quality similarity threshold set by the system is 0.85. When the sound quality similarity between the mobile device and the car speaker is lower than this threshold, the tuning strategy is triggered.

[0014] Frequency difference threshold: The maximum allowable value of the frequency difference is set to 200Hz. When it is detected that the frequency difference between the mobile device and the vehicle speaker exceeds this threshold, the adaptive filter performs correction.

[0015] An audio optimization system for in-car screen projection, the system comprising:

[0016] A screen projection module is used to establish a connection between a mobile device and a vehicle-mounted display screen through a screen projection protocol or an interconnection protocol;

[0017] The interface judgment module is used to detect the number of speakers in the car through the car speaker interface to determine whether the sound field compensation function needs to be triggered; and during the sound field compensation, the audio information in the car is obtained through the microphone interface of the car, and the sound quality similarity value between the mobile device speaker and the car speaker is generated to determine whether the tuning strategy needs to be executed;

[0018] A function trigger module, used to automatically trigger the sound field compensation function when the number of speakers in the car is less than or equal to the speaker number threshold, call the mobile device speaker and the car machine speaker to perform co-frequency coordinated sound, and trigger the tuning strategy when the sound quality similarity value is lower than the sound quality similarity threshold;

[0019] The strategy execution module is used to generate a tuning strategy according to the preset matching logic, and send instructions to the mobile device and the vehicle computer to adjust the EQ mode;

[0020] The user interaction module is used for the user to manually select the trigger mode of the sound field compensation function, view the execution progress of the tuning strategy or set a personalized tuning strategy, and control the volume and sound effect mode of the mobile device speakers and the car speakers.

[0021] Preferably, the screen projection module includes:

[0022] A video transmission unit, used to transmit the video content of the mobile device to the vehicle display screen via wireless or wired connection;

[0023] The audio transmission unit is used to transmit the audio signal from the mobile device to the vehicle speakers.

[0024] Preferably, the interface determination module includes:

[0025] The audio monitoring unit is used to obtain the audio signal in the car in real time through the microphone interface of the car computer, continuously analyze the sound spectrum in the car, extract the frequency characteristics of the ambient noise, and determine the ambient noise level in the car;

[0026] The sound quality similarity calculation unit is used to calculate the sound quality similarity value between the mobile device speaker and the vehicle head unit speaker. The calculation process is as follows:

[0027] Step 1: Input audio signal, use represents the audio signal from the mobile device speaker, Represents the audio signal of the car speaker; use short-time Fourier transform STFT to and Converted to frequency domain representation, respectively and , where f represents frequency and t represents time;

[0028] Step 2: Representation in frequency domain and Extract audio signals separately and The spectral characteristics of and , representing the audio feature vectors of the mobile device and the car machine respectively;

[0029] Step 3: Add frequency weight After weighted processing, the preliminary sound quality similarity calculation formula is:

[0030]

[0031] in, Represents preliminary sound quality similarity; represents the characteristic value of the audio signal of the mobile device speaker at the frequency f; Represents the characteristic value of the audio signal of the car speaker at frequency f;

[0032] Step 4: Automatically adjust frequency weights based on user preferences or environment through a dynamic adjustment mechanism , the dynamic weight adjustment formula is:

[0033]

[0034] Among them, α represents the rate parameter of control weight adjustment; Reference values ​​representing frequencies, used to dynamically adjust weights based on user preferences or audio environment;

[0035] Step 5: Combine the preliminary sound quality similarity and the subjective sound quality evaluation, balance them through the weight parameter β, and calculate the perceived sound quality score as the final sound quality similarity value. The calculation formula is:

[0036]

[0037] Among them, β represents the weight coefficient; Represents the subjective sound quality assessment score;

[0038] Step 6: Based on the final perceived sound quality score , to determine whether the tuning strategy needs to be executed. If the perceived sound quality score If the sound quality similarity value is lower than the set threshold, the tuning strategy needs to be executed, otherwise it will not be executed.

[0039] Preferably, the mobile device speaker and the vehicle headphone speaker perform synchronous sound generation, and the implementation process includes:

[0040] Step 1: Audio signal to the mobile device speaker and audio signals from the car speakers Perform windowing processing respectively to form windowed signals and , using the window function Improve the frequency resolution, the expression is:

[0041]

[0042] Where t represents time;

[0043] Apply wavelet transform to the windowed signal to obtain the wavelet coefficients in each frequency band and , the expression is:

[0044]

[0045] in, Represents the windowed signal In scale and the wavelet transform coefficients at position b; Represents the windowed signal In scale and the wavelet transform coefficients at position b; is the mother wavelet function; is the scale parameter, which controls the resolution of the signal in the frequency domain; b is the time shift parameter, which controls the time resolution;

[0046] Analyze the frequency spectrum differences between the mobile device speaker and the car speaker signal at different scales and time shifts to generate preliminary frequency difference values ;

[0047] Step 2: Use adaptive filter to adjust the frequency difference Perform optimization and adjust to calculate the filter error signal , the formula is:

[0048]

[0049] in, is the error signal, representing the ideal output signal The actual output signal of the filter The difference between

[0050] The update formula of the filter coefficient is:

[0051]

[0052] in: Represents the coefficient of the filter at the nth iteration; μ is the learning rate, which controls the adjustment step size; is the delayed term of the input signal; k represents the updated filter coefficient;

[0053] Step 3: When the optimized frequency difference value is lower than the preset frequency difference threshold, the sound synchronization between the mobile device speaker and the vehicle headphone speaker is determined; if the optimized frequency difference value is greater than the preset frequency difference threshold, an adjustment instruction is issued through the control system to adjust the synchronous sound frequency between the mobile device speaker and the vehicle headphone speaker again;

[0054] Step 4: During the synchronous sounding process, continuously monitor the frequency difference between the mobile device speaker and the vehicle headphone speaker.

[0055] Preferably, the summary execution module includes:

[0056] A strategy matching engine, which is deployed on a cloud server and is used to receive data from the interface judgment module and generate a tuning strategy according to a preset matching logic;

[0057] The instruction execution unit is used to receive the tuning instructions from the strategy matching engine and convert them into control signals, which are sent to the mobile device speaker and the vehicle headphone speaker respectively.

[0058] Preferably, the strategy matching engine includes:

[0059] The sound quality comparison unit is used to obtain the in-vehicle audio information through the vehicle microphone interface, compare the audio frequency band of the vehicle speaker with the audio frequency band of the mobile device speaker, and generate a frequency band difference value;

[0060] The EQ mode adjustment unit is used to generate a tuning strategy when the frequency band difference value is greater than the frequency band difference threshold, adjust the EQ mode of the mobile terminal and the vehicle terminal, and adjust the frequency band to the range of 500Hz to 2KHz.

[0061] Preferably, the system also includes a unified verification module, which is used to continuously monitor the sound quality changes through the in-vehicle microphone interface after the EQ mode adjustment is completed. If the sound quality similarity value is still lower than the sound quality similarity threshold, the unified verification module will feedback to the server, and the server will issue an adjustment instruction again and repeat the tuning strategy until the sound quality similarity reaches the preset standard.

[0062] Preferably, the user interaction module includes:

[0063] The sound field compensation control module is used for the user to manually select whether to enable the coordinated sound function of the mobile device speaker and the vehicle headphone speaker;

[0064] The sound quality optimization progress display module is used to display the execution progress and results of the tuning strategy in real time.

[0065] An audio optimization method for an audio optimization system for in-car screen projection, the method comprising:

[0066] The mobile device is connected to the vehicle display screen through the screen projection protocol or the interconnection protocol, and the audio signal of the mobile device is transmitted to the vehicle speaker;

[0067] Detecting the number of speakers in the car through the car speaker interface to determine whether the number of speakers in the car is less than or equal to the speaker number threshold. If so, the sound field compensation function is triggered, otherwise it is not triggered;

[0068] The audio signals of the mobile device speaker and the vehicle head speaker are obtained in real time, the frequency difference value is calculated, and the frequency difference is corrected by using an adaptive filter. When the corrected frequency difference value is less than a preset frequency difference threshold, the vehicle head speaker and the mobile device speaker reach the same frequency sounding standard;

[0069] During the sound field compensation process, the in-car audio information is obtained through the microphone interface of the car computer, and the sound quality similarity value between the mobile device speaker and the car computer speaker is calculated. When the sound quality similarity value is lower than the sound quality similarity threshold, the tuning strategy is triggered;

[0070] A strategy matching engine is deployed on the cloud server to obtain in-car audio information through the car microphone interface, and the audio frequency band of the car speaker is compared with the audio frequency band of the mobile device speaker to generate a frequency band difference value. When the frequency band difference value is greater than the frequency band difference threshold, a tuning strategy is generated and instructions are sent to the mobile device and the car respectively to adjust the EQ mode of the mobile terminal and the car terminal to optimize the audio output.

[0071] After the EQ mode adjustment is completed, the sound quality similarity value is continuously monitored through the in-vehicle microphone interface. If the sound quality similarity value is still lower than the sound quality similarity threshold, it is fed back to the cloud server and the tuning strategy is repeated until the sound quality similarity reaches the preset standard.

[0072] Preferably, the method further comprises an audio optimization step based on a user preset configuration, the step comprising:

[0073] The user inputs personalized audio parameter configuration through the user interaction interface, wherein the configuration includes volume adjustment, EQ frequency band adjustment and audio delay control;

[0074] The car system adjusts the audio output of the mobile device speakers and the car speakers in real time according to the personalized configuration input by the user;

[0075] When the ambient noise in the car changes beyond the preset noise threshold, the system automatically adjusts the volume or audio frequency band.

[0076] Compared with the prior art, the beneficial effect of the present invention is that the present invention can obtain the audio signals of the car machine speaker and the mobile device speaker in real time by introducing an adaptive filter and a frequency difference calculation unit, analyze the audio frequency difference between the two, dynamically adjust the sound frequency, and make the synchronous sound of the speaker reach the standard, thereby improving the problem of the sound quality being out of sync between the mobile device speaker and the car machine speaker, and significantly improving the synchronization and overall hearing of the audio in the car. When the system detects that the number of speakers in the car is insufficient, the sound field compensation function is automatically triggered, and the mobile device speaker and the car machine speaker are called to coordinate the same frequency sound, which enhances the coverage of the sound effect in the car, solves the problem of incomplete sound field coverage caused by the small number of speakers in the car, and improves the user's auditory experience. The system monitors the ambient noise in the car in real time through the microphone interface of the car machine, and automatically adjusts the volume and EQ mode of the mobile device and the car machine speaker according to the change of the noise level, ensuring that passengers can always obtain clear and stable audio output in different noise environments, and overcoming the problem of poor sound quality performance in complex noise environments in the prior art. Users can also manually select the trigger mode of the sound field compensation function through the interactive interface, and set personalized audio parameters such as volume, EQ frequency band, etc. to meet personalized needs. Through the strategy matching engine deployed in the cloud, the system can generate and issue tuning strategies based on the noise level and number of speakers in the car, realizing the automatic integration of the sound quality of the mobile device speakers and the car speakers, further improving the sound quality performance. The system combines real-time audio signal analysis technology and the intelligent tuning function of the strategy matching engine to automatically optimize the sound quality output, improve the clarity of the sound quality, the balance of the sound effects and the stability of the sound field, and adapt to various driving scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0078] Figure 1 It is a schematic diagram of the modular structure of the system of the present invention; Figure 2 Schematic diagram of the working process of the adaptive filter of the present invention; Figure 3 It is a schematic diagram of the flow of the sound field compensation function of the present invention;

[0079] Figure 4 It is a schematic diagram of the EQ mode adjustment process of the present invention; Figure 5 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0080] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0081] Example 1

[0082] like Figure 1 As shown in FIG. 1 , an embodiment of the present invention is provided, which provides an audio optimization system for in-car screen projection, including:

[0083] Screen projection module, used to establish a connection between the mobile device and the vehicle display screen through screen projection protocol or interconnection protocol (such as AirPlay, DLNA, Miracast, etc.);

[0084] The mobile device is connected to the vehicle display screen through the AirPlay, DLNA or Miracast protocol, the video content is transmitted wirelessly to the vehicle display screen, and the audio signal is output through the vehicle speakers. When the audio signal is transmitted, the system transmits and synchronizes the audio signal in the mobile device with the audio signal of the vehicle speakers in real time through the audio transmission unit.

[0085] Specifically, the screen projection module includes:

[0086] A video transmission unit, used to transmit the video content of the mobile device to the vehicle display screen via wireless or wired connection;

[0087] The audio transmission unit is used to transmit the audio signal from the mobile device to the vehicle speakers.

[0088] Further, such as Figure 2 , Figure 3 As shown, it is used to detect the number of speakers in the car through the car speaker interface to determine whether the sound field compensation function needs to be triggered; and during the sound field compensation, the car audio information is obtained through the microphone interface of the car, and the sound quality similarity value between the mobile device speaker and the car speaker is generated to determine whether the tuning strategy needs to be executed;

[0089] The system detects the number of speakers and noise level in the car in real time through the car microphone interface. By analyzing the noise spectrum, the noise frequency characteristic value is generated and compared with the preset noise threshold. When the noise level exceeds the threshold and the number of speakers in the car is less than the speaker number threshold, the system triggers the sound field compensation function.

[0090] Specifically, the interface judgment module includes:

[0091] The audio monitoring unit is used to obtain the audio signal in the car in real time through the microphone interface of the car computer, continuously analyze the sound spectrum in the car, extract the frequency characteristics of the ambient noise, and determine the ambient noise level in the car;

[0092] The sound quality similarity calculation unit is used to calculate the sound quality similarity value between the mobile device speaker and the vehicle head unit speaker. The calculation process is as follows:

[0093] Step 1: Input audio signal, use represents the audio signal from the mobile device speaker, Represents the audio signal of the car speaker; use short-time Fourier transform STFT to and Converted to frequency domain representation, respectively and , where f represents frequency and t represents time;

[0094] Step 2: Representation in frequency domain and Extract audio signals separately and The spectral characteristics of and , representing the audio feature vectors of the mobile device and the car machine respectively;

[0095] Step 3: Add frequency weight After weighted processing, the preliminary sound quality similarity calculation formula is:

[0096]

[0097] in, Represents preliminary sound quality similarity; represents the characteristic value of the audio signal of the mobile device speaker at the frequency f; Represents the characteristic value of the audio signal of the car speaker at frequency f;

[0098] Step 4: Automatically adjust frequency weights based on user preferences or environment through a dynamic adjustment mechanism , the dynamic weight adjustment formula is:

[0099]

[0100] Among them, α represents the rate parameter of control weight adjustment; Reference values ​​representing frequencies, used to dynamically adjust weights based on user preferences or audio environment;

[0101] Step 5: Combine the preliminary sound quality similarity and the subjective sound quality evaluation, balance them through the weight parameter β, and calculate the perceived sound quality score as the final sound quality similarity value. The calculation formula is:

[0102]

[0103] Among them, β represents the weight coefficient; Represents the subjective sound quality assessment score;

[0104] Step 6: Based on the final perceived sound quality score , to determine whether the tuning strategy needs to be executed. If the perceived sound quality score If the sound quality similarity value is lower than the set threshold, the tuning strategy needs to be executed, otherwise it will not be executed.

[0105] In the vehicle voice recognition system, the interface judgment module plays a vital role. This module detects and processes the sound signals in the car by obtaining two key interfaces on the vehicle side: the speaker interface and the microphone interface. Specifically, the interface judgment module first obtains the number of speakers in the car through the speaker interface. When it is detected that the number of speakers in the car is less than or equal to 6, the module will trigger the sound field compensation function to improve the audio effect in the car.

[0106] At the same time, the interface judgment module also obtains the sound quality information in the car through the microphone interface. In order to evaluate the similarity between the sounds on the mobile phone and the vehicle, the module introduces the concept of a similarity value and initializes it to 1. During sound field compensation, the module continues to monitor changes in the similarity value. When the similarity value is greater than 0.5, the module assumes by default that the sound emitted by the mobile phone is highly similar to the sound emitted by the vehicle, so no additional optimization operations are required. However, when the similarity value is less than or equal to 0.5, the module will determine that there is a large difference between the sounds on the mobile phone and the vehicle, thereby triggering the tuning strategy to further optimize the audio in the car.

[0107] In addition, the interface judgment module also obtains the audio signal in the car in real time through the microphone interface of the car computer and judges the ambient noise level in the car. The unit will continuously analyze the sound spectrum in the car and extract the frequency characteristics of the ambient noise, while the audio adjustment unit is responsible for triggering the volume adjustment function to match the volume of the mobile device speaker and the car computer speaker to ensure that passengers can still hear the audio output clearly in a high-noise environment.

[0108] Furthermore, the function trigger module is used to automatically trigger the sound field compensation function when the number of speakers in the car is less than or equal to the speaker number threshold, call the mobile device speaker and the car machine speaker to perform the same frequency coordinated sound, and trigger the tuning strategy when the sound quality similarity value is lower than the sound quality similarity threshold;

[0109] Specifically, the mobile device speaker and the vehicle head speaker perform synchronous sound generation, and the implementation process includes:

[0110] Step 1: Audio signal to the mobile device speaker and audio signals from the car speakers Perform windowing processing respectively to form windowed signals and , using the window function Improve the frequency resolution, the expression is:

[0111]

[0112] Where t represents time;

[0113] Apply wavelet transform to the windowed signal to obtain the wavelet coefficients in each frequency band and , the expression is:

[0114]

[0115] in, Represents the windowed signal In scale and the wavelet transform coefficients at position b; Represents the windowed signal In scale and the wavelet transform coefficients at position b; is the mother wavelet function; is the scale parameter, which controls the resolution of the signal in the frequency domain; b is the time shift parameter, which controls the time resolution;

[0116] Analyze the frequency spectrum differences between the mobile device speaker and the car speaker signal at different scales and time shifts to generate preliminary frequency difference values ;

[0117] Step 2: Use adaptive filter to adjust the frequency difference Perform optimization and adjust to calculate the filter error signal , the formula is:

[0118]

[0119] in, is the error signal, representing the ideal output signal The actual output signal of the filter The difference between

[0120] The update formula of the filter coefficient is:

[0121]

[0122] in: Represents the coefficient of the filter at the nth iteration; μ is the learning rate, which controls the adjustment step size; is the delayed term of the input signal; k represents the updated filter coefficient;

[0123] Step 3: When the optimized frequency difference value is lower than the preset frequency difference threshold, the sound synchronization between the mobile device speaker and the vehicle headphone speaker is determined; if the optimized frequency difference value is greater than the preset frequency difference threshold, an adjustment instruction is issued through the control system to adjust the synchronous sound frequency between the mobile device speaker and the vehicle headphone speaker again;

[0124] Step 4: During the synchronous sounding process, continuously monitor the frequency difference between the mobile device speaker and the vehicle headphone speaker.

[0125] Furthermore, the strategy execution module is used to generate a tuning strategy according to a preset matching logic, and issue instructions to both the mobile device and the vehicle computer to adjust the EQ mode;

[0126] When the sound quality similarity value is detected to be lower than 0.85, the strategy matching engine generates a personalized tuning strategy on the cloud server and sends the command to the mobile device and the vehicle system. The system adjusts the EQ mode of the speaker according to the generated tuning strategy, and the audio output range is set between 500Hz and 2KHz. Users can view the tuning progress through the interactive interface and manually adjust the sound quality parameters.

[0127] Specifically, Figure 4 As shown, the policy execution module includes:

[0128] The policy execution module includes:

[0129] A strategy matching engine, which is deployed on a cloud server and is used to receive data from the interface judgment module and generate a tuning strategy according to a preset matching logic;

[0130] The instruction execution unit is used to receive the tuning instructions from the strategy matching engine and convert them into control signals, which are sent to the mobile device speaker and the vehicle headphone speaker respectively.

[0131] Specifically, the strategy matching engine includes:

[0132] The sound quality comparison unit is used to obtain the in-vehicle audio information through the vehicle microphone interface, compare the audio frequency band of the vehicle speaker with the audio frequency band of the mobile device speaker, and generate a frequency band difference value;

[0133] The EQ mode adjustment unit is used to generate a tuning strategy when the frequency band difference value is greater than the frequency band difference threshold, adjust the EQ mode of the mobile terminal and the vehicle terminal, and adjust the frequency band to the range of 500Hz to 2KHz.

[0134] Among them, the system also includes a unified verification module, which is used to continuously monitor the sound quality changes through the in-vehicle microphone interface after the EQ mode adjustment is completed. If the sound quality similarity value is still lower than the sound quality similarity threshold, the unified verification module will feedback to the server, and the server will issue an adjustment instruction again and repeat the tuning strategy until the sound quality similarity reaches the preset standard.

[0135] Furthermore, the user interaction module includes:

[0136] The sound field compensation control module is used for the user to manually select whether to enable the coordinated sound function of the mobile device speaker and the vehicle headphone speaker;

[0137] The sound quality optimization progress display module is used to display the execution progress and results of the tuning strategy in real time.

[0138] Example 2

[0139] like Figure 5 As shown in FIG. 1 , an embodiment of the present invention is provided, which provides an audio optimization method for an audio optimization system for in-car screen projection, including:

[0140] Step S1: Establish a connection between the mobile device and the vehicle display screen through a screen projection protocol or an interconnection protocol, and transmit the audio signal of the mobile device to the vehicle speaker;

[0141] Step S2: Detecting the number of speakers in the vehicle through the vehicle speaker interface to determine whether the number of speakers in the vehicle is less than or equal to a speaker number threshold. If so, triggering the sound field compensation function, otherwise not triggering;

[0142] Step S3: acquiring audio signals from the mobile device speaker and the vehicle head speaker in real time, calculating the frequency difference value, and correcting the frequency difference using an adaptive filter. When the corrected frequency difference value is less than a preset frequency difference threshold, the vehicle head speaker and the mobile device speaker reach the same frequency sounding standard.

[0143] Step S4: During the sound field compensation process, the in-vehicle audio information is obtained through the microphone interface of the vehicle computer, and the sound quality similarity value between the mobile device speaker and the vehicle computer speaker is calculated. When the sound quality similarity value is lower than the sound quality similarity threshold, the tuning strategy is triggered;

[0144] Step S5: deploying a strategy matching engine on the cloud server, obtaining in-car audio information through the car machine microphone interface, comparing the audio frequency band of the car machine speaker with the audio frequency band of the mobile device speaker, and generating a frequency band difference value; when the frequency band difference value is greater than the frequency band difference threshold, generating a tuning strategy, and sending instructions to the mobile device and the car machine respectively, adjusting the EQ mode of the mobile terminal and the car machine, and optimizing the audio output;

[0145] Step S6: After the EQ mode adjustment is completed, the sound quality similarity value is continuously monitored through the in-vehicle microphone interface. If the sound quality similarity value is still lower than the sound quality similarity threshold, it is fed back to the cloud server and the tuning strategy is repeated until the sound quality similarity reaches the preset standard.

[0146] The method further includes an audio optimization step based on a user preset configuration, the step comprising:

[0147] The user inputs personalized audio parameter configuration through the user interaction interface, wherein the configuration includes volume adjustment, EQ frequency band adjustment and audio delay control;

[0148] The car system adjusts the audio output of the mobile device speakers and the car speakers in real time according to the personalized configuration input by the user;

[0149] When the ambient noise in the car changes beyond the preset noise threshold, the system automatically adjusts the volume or audio frequency band.

[0150] Example 3

[0151] This embodiment introduces the use scenarios of audio optimization after in-car screen projection or interconnection, which are mainly divided into the following two categories:

[0152] Automatic audio tuning scenario: After screen projection or interconnection in the car, such as when the user plays music or watches a movie, the system recognizes the current audio effect through the speakers in the car and automatically performs audio tuning as needed.

[0153] Specific steps:

[0154] The user connects the mobile phone to the car display screen through the screen projection protocol, and the system starts playing the audio content on the mobile device.

[0155] The system monitors the audio output in the car in real time through the car microphone interface and evaluates the sound quality of the current speakers in the car.

[0156] If the system detects that the audio output effect is insufficient, it will trigger the sound quality optimization function and automatically adjust the coordinated sound frequency of the car speaker and the mobile phone speaker to achieve better sound quality.

[0157] Sound field compensation scenario: When the number of speakers in the car is insufficient, the system will supplement the sound field through the mobile phone speakers to improve the overall sound experience.

[0158] Specific steps:

[0159] After users project the screen or connect to the Internet, the sound field coverage is insufficient due to the small number of speakers in the car.

[0160] When the system detects that the number of speakers in the car is lower than the preset threshold, it automatically calls the mobile phone speaker as a volume compensator to coordinate with the car computer speakers to enhance the sound effects in the car.

[0161] By adjusting the audio output through the cloud server, the sound quality between the mobile phone speakers and the car speakers is integrated, ensuring that users have a more immersive audio experience in the car.

[0162] Example 4

[0163] In this embodiment, the system controls the EQ modes of the mobile device and the vehicle terminal through the server, and compares and adjusts the frequency bands of the audio emitted by them to ensure that the sound quality similarity meets the preset standards.

[0164] The specific steps are as follows:

[0165] Audio signal acquisition and transmission: When there are not enough speakers in the car environment or the sound field coverage is incomplete, the system automatically triggers the speakers of the mobile device to coordinate with the car speakers for audio output.

[0166] The audio signals emitted by the car speakers and mobile device speakers are collected through the in-car microphone interface, and these signals are transmitted to the server for processing after different delays.

[0167] Frequency band setting and analysis The server divides the received audio signal into two main frequency bands, named as frequency band m and frequency band n.

[0168] Frequency band m and frequency band n represent the main frequency ranges of the audio signals of the vehicle head speaker and the mobile device speaker, respectively.

[0169] Frequency band comparison process: The server will place the two frequency bands in the same comparison area, and the system will analyze the sound quality differences between the two frequency bands in real time.

[0170] When the system detects that the difference between the two frequency bands reaches 0.5 or more, the system automatically triggers the EQ mode adjustment strategy. The specific adjustment steps include weighting different frequencies in the two frequency bands to ensure that the sound quality characteristics of the two in the same audio range are similar.

[0171] EQ mode adjustment:

[0172] The system adjusts the EQ mode of the mobile device speakers and the car speakers according to the server's tuning strategy, adjusting the main range of the audio frequency band to between 500Hz and 2KHz.

[0173] The adjusted EQ mode ensures that the difference in sound quality between the two frequency bands is reduced, ultimately achieving similar or identical sound effects, so that users hear the sound without a noticeable disconnect between the sound in the car and the sound coming from the speakers of the mobile device.

[0174] Feedback Mechanism:

[0175] After completing the EQ mode adjustment, the system continuously monitors the similarity of the audio signal through the microphone interface of the car computer. If the similarity is still lower than the preset sound quality similarity threshold, the system will trigger the audio tuning process again until the two meet the sound quality similarity requirements.

[0176] In summary, the present invention provides an audio optimization system and method for in-car screen projection. Through the collaborative work of the screen projection module, the interface judgment module, the function trigger module and the strategy execution module, the number of speakers in the car and the level of environmental noise can be effectively detected, and the sound field compensation and audio optimization strategies can be triggered according to the sound quality similarity. In particular, the present invention introduces an adaptive filter and a cloud-based strategy matching engine to achieve frequency difference correction and real-time EQ mode adjustment between the car speakers and the mobile device speakers, ensuring the stability and synchronization of sound quality in complex environments. In addition, users can customize audio parameters through the interactive interface, further enhancing the personalized audio experience. The present invention overcomes the problems of poor sound quality synchronization, insufficient sound effect coverage and noise interference in the prior art, and is suitable for various in-car audio systems, effectively improving the overall quality of in-car audio playback and user experience.

[0177] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0178] Any process or method description in the flow chart or otherwise described herein can be understood to represent a module, fragment or portion of a code including one or more executable instructions for implementing the steps of a specific logical function or process. And the scope of the preferred embodiment of the present application includes other implementations, in which the functions may not be performed in the order shown or discussed, including in a substantially simultaneous manner or in a reverse order according to the functions involved.

[0179] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An audio optimization system for in-car screen projection, characterized in that: The system comprises: A screen projection module is used to establish a connection between a mobile device and a vehicle-mounted display screen through a screen projection protocol or an interconnection protocol; The interface judgment module is used to detect the number of speakers in the car through the car speaker interface to determine whether the sound field compensation function needs to be triggered; and during the sound field compensation, the audio information in the car is obtained through the microphone interface of the car, and the sound quality similarity value between the mobile device speaker and the car speaker is generated to determine whether the tuning strategy needs to be executed; The interface judgment module includes: The audio monitoring unit is used to obtain the audio signal in the car in real time through the microphone interface of the car computer, continuously analyze the sound spectrum in the car, extract the frequency characteristics of the ambient noise, and determine the ambient noise level in the car; The sound quality similarity calculation unit is used to calculate the sound quality similarity value between the mobile device speaker and the vehicle head unit speaker. The calculation process is as follows: Step 1: Input audio signal, use X m (t) represents the audio signal of the mobile device speaker, X c (t) represents the audio signal of the car speaker; use short-time Fourier transform STFT to transform X m (t) and X c (t) is converted into frequency domain representation and denoted as F m (f,t) and F c (f, t), where f represents frequency and t represents time; Step 2: Express F in the frequency domain m (f,t) and F c (f, t) respectively extract the audio signal X m (t) and X c The spectral characteristics of (t) are obtained, and the characteristic vectors are recorded as h m (f) and h c (f),represents the audio feature vectors of the mobile device and the car machine, respectively; Step 3: Add frequency weight w(f) for weighted processing. The preliminary sound quality similarity calculation formula is: Among them, Similarity improved Represents the preliminary sound quality similarity; h m (f) represents the characteristic value of the audio signal of the mobile device speaker at frequency f; h c (f) represents the characteristic value of the audio signal of the vehicle head unit speaker at frequency f; Step 4: Automatically adjust the frequency weight w(f) according to user preference or environment. The dynamic weight adjustment formula is: Where α represents the rate parameter for controlling weight adjustment; f0 represents the reference value of frequency, which is used to dynamically adjust the weight according to user preference or audio environment; Step 5: Combine the preliminary sound quality similarity and the subjective sound quality evaluation, balance them through the weight parameter β, and calculate the perceived sound quality score as the final sound quality similarity value. The calculation formula is: Perceptual Score=β*Similarity improved +(1-β)*Subjective Quality Among them, β represents the weight coefficient; Subjective Quality represents the subjective sound quality evaluation score; Step 6: According to the final perceived sound quality score Perceptual Score, determine whether to execute the tuning strategy. If the perceived sound quality score Perceptual Score is lower than the set sound quality similarity value threshold, the tuning strategy needs to be executed, otherwise it is not executed; A function trigger module, used to automatically trigger the sound field compensation function when the number of speakers in the car is less than or equal to the speaker number threshold, call the mobile device speaker and the car machine speaker to perform co-frequency coordinated sound, and trigger the tuning strategy when the sound quality similarity value is lower than the sound quality similarity threshold; The strategy execution module is used to generate a tuning strategy according to the preset matching logic, and send instructions to the mobile device and the vehicle computer to adjust the EQ mode; The user interaction module is used for the user to manually select the trigger mode of the sound field compensation function, view the execution progress of the tuning strategy or set a personalized tuning strategy, and control the volume and sound effect mode of the mobile device speakers and the car speakers.

2. The audio optimization system for in-car screen projection according to claim 1, characterized in that: The screen projection module includes: A video transmission unit, used to transmit the video content of the mobile device to the vehicle display screen via wireless or wired connection; The audio transmission unit is used to transmit the audio signal from the mobile device to the vehicle speakers.

3. The audio optimization system for in-car screen projection according to claim 1, characterized in that: The mobile device speaker and the vehicle head speaker perform synchronous sound generation, and the implementation process includes: Step 1: X the audio signal to the mobile device speaker m (t) and the audio signal X of the car speaker c (t) are windowed to form windowed signals x1(t) and x2(t) respectively. The window function w(t) is used to improve the frequency resolution. The expression is: x1(t)=X m (t)*w(t),x2(t)=X c (t)*w(t) Where t represents time; Apply wavelet transform to the windowed signal to obtain the wavelet coefficients Wx1(a,b) and Wx2(a,b) in each frequency band, expressed as: Where Wx1(a,b) represents the wavelet transform coefficient of the windowed signal x1(t) at scale a and position b; Wx2(a,b) represents the wavelet transform coefficient of the windowed signal x2(t) at scale a and position b; ψ is the mother wavelet function; a is the scale parameter, which controls the resolution of the signal in the frequency domain; b is the time shift parameter, which controls the time resolution; Analyze the spectrum differences between the mobile device speaker and the car speaker signals at different scales and time shifts to generate a preliminary frequency difference value Δf1; Step 2: Use an adaptive filter to optimize and adjust the frequency difference value Δf1, and calculate the filter error signal e(n), the formula is: e(n)=d(n)-y(n) Where e(n) is the error signal, which represents the difference between the ideal output signal d(n) and the actual output signal y(n) of the filter; The update formula of the filter coefficient is: h n+1 (k)=h n (k)+μ*e(n)*x(n-k) Where: h n (k) represents the coefficient of the filter at the nth iteration; μ is the learning rate, which controls the adjustment step size; x(nk) is the delay term of the input signal; k represents the updated filter coefficient; Step 3: When the optimized frequency difference value is lower than the preset frequency difference threshold, the sound synchronization between the mobile device speaker and the vehicle headphone speaker is determined; if the optimized frequency difference value is greater than the preset frequency difference threshold, an adjustment instruction is issued through the control system to adjust the synchronous sound frequency between the mobile device speaker and the vehicle headphone speaker again; Step 4: During the synchronous sounding process, continuously monitor the frequency difference between the mobile device speaker and the vehicle headphone speaker.

4. The audio optimization system for in-car screen projection according to claim 1, characterized in that: The policy execution module includes: A strategy matching engine, which is deployed on a cloud server and is used to receive data from the interface judgment module and generate a tuning strategy according to a preset matching logic; The instruction execution unit is used to receive the tuning instructions from the strategy matching engine and convert them into control signals, which are sent to the mobile device speaker and the vehicle headphone speaker respectively.

5. The audio optimization system for in-car screen projection according to claim 4 is characterized in that: The strategy matching engine includes: The sound quality comparison unit is used to obtain the in-vehicle audio information through the vehicle microphone interface, compare the audio frequency band of the vehicle speaker with the audio frequency band of the mobile device speaker, and generate a frequency band difference value; The EQ mode adjustment unit is used to generate a tuning strategy when the frequency band difference value is greater than the frequency band difference threshold, adjust the EQ mode of the mobile terminal and the vehicle terminal, and adjust the frequency band to the range of 500Hz to 2KHz.

6. The audio optimization system for in-car screen projection according to claim 1, characterized in that: The system also includes a unified verification module, which is used to continuously monitor the sound quality changes through the in-vehicle microphone interface after the EQ mode adjustment is completed. If the sound quality similarity value is still lower than the sound quality similarity threshold, the unified verification module will feedback to the server, and the server will issue an adjustment instruction again and repeat the tuning strategy until the sound quality similarity reaches the preset standard.

7. The audio optimization system for in-car screen projection according to claim 1, characterized in that: The user interaction module comprises: The sound field compensation control module is used for the user to manually select whether to enable the coordinated sound function of the mobile device speaker and the vehicle headphone speaker; The sound quality optimization progress display module is used to display the execution progress and results of the tuning strategy in real time.

8. An audio optimization method for an audio optimization system for in-car screen projection based on any one of claims 1-7, characterized in that: The method comprises: Establish a connection between the mobile device and the vehicle display screen through the screen projection protocol or the interconnection protocol, and transmit the audio signal of the mobile device to the vehicle speaker; detect the number of speakers in the vehicle through the vehicle speaker interface, and determine whether the number of speakers in the vehicle is less than or equal to the speaker number threshold. If so, the sound field compensation function is triggered, otherwise it is not triggered; The audio signals of the mobile device speaker and the vehicle head speaker are obtained in real time, the frequency difference value is calculated, and the frequency difference is corrected by using an adaptive filter. When the corrected frequency difference value is less than a preset frequency difference threshold, the vehicle head speaker and the mobile device speaker reach the same frequency sounding standard; During the sound field compensation process, the in-car audio information is obtained through the microphone interface of the car computer, and the sound quality similarity value between the mobile device speaker and the car computer speaker is calculated. When the sound quality similarity value is lower than the sound quality similarity threshold, the tuning strategy is triggered; A strategy matching engine is deployed on the cloud server, and the in-car audio information is obtained through the in-car microphone interface. The audio frequency band emitted by the in-car speaker is compared with the audio frequency band emitted by the mobile device speaker to generate a frequency band difference value. When the frequency band difference value is greater than the frequency band difference threshold, a tuning strategy is generated, and instructions are sent to the mobile device and the in-car respectively to adjust the EQ mode of the mobile and in-car terminals to optimize the audio output. After the EQ mode adjustment is completed, the sound quality similarity value is continuously monitored through the in-car microphone interface. If the sound quality similarity value is still lower than the sound quality similarity threshold, it is fed back to the cloud server and the tuning strategy is repeated until the sound quality similarity reaches the preset standard.

9. The audio optimization method for the audio optimization system for in-car screen projection according to claim 8, characterized in that: The method further comprises an audio optimization step based on a user preset configuration, the step comprising: The user inputs personalized audio parameter configuration through the user interaction interface, wherein the configuration includes volume adjustment, EQ frequency band adjustment and audio delay control; The car system adjusts the audio output of the mobile device speakers and the car speakers in real time according to the personalized configuration input by the user; When the ambient noise in the car changes beyond the preset noise threshold, the system automatically adjusts the volume or audio frequency band.

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