Audio codec apparatus, method and system with feedback suppression function

Abstract

This application provides an audio codec apparatus, method, and system with feedback suppression functionality. By integrating the feedback suppression function within the audio codec, and incorporating a spectrum shifting unit and an automatic frequency control unit in the uplink path of the audio codec, while simultaneously setting up a dynamic compression and limiting unit in the downlink path, the synergistic effect of these units reduces the feedback suppression delay time. This allows for flexible adaptation to various acoustic environments and feedback types while maintaining sound quality. Furthermore, algorithms can be used to perform corresponding feedback suppression operations on the input near-end audio signal to adapt to dynamic changes in feedback suppression scenarios, while maintaining consistency in sound quality and volume, thus avoiding loss of original audio quality.

Description

Technical Field

[0001] This application relates to the field of audio codecs, and in particular to an audio codec apparatus, method and system with feedback suppression function. Background Technology

[0002] Audio codecs are widely used in various audio processing scenarios. The primary function of these hardware devices is to convert analog audio signals to digital formats and vice versa. This capability makes audio codecs a crucial component in many industries, including music production, radio broadcasting, telephone communications, and film post-production. However, existing audio codecs still cannot solve technical challenges in public address systems, such as feedback suppression. Feedback suppression is an important audio processing technique used to reduce or eliminate unwanted sharp, high-volume noise generated by feedback loops in audio systems. This phenomenon typically occurs when a microphone captures sound from a speaker and amplifies it again, forming a self-reinforcing feedback loop. Feedback is not only unpleasant but can also damage audio equipment and affect the clarity of voice communication. Effective feedback suppression techniques not only improve audio quality and protect audio equipment but also enhance the listener experience.

[0003] Currently, common feedback suppression methods include using directional microphones, adjusting the layout of audio equipment, and manually adjusting volume and frequency. Technical methods include frequency shifting, dynamic range compression, and adaptive feedback cancellation (AFC) in digital signal processing. These methods aim to identify, reduce, or eliminate frequency components that may cause feedback. However, existing technologies cannot adapt to constantly changing acoustic environments, especially in complex or non-standard audio setups. Manual adjustment requires specialized knowledge and is not suitable for dynamic scenarios. Existing digital processing technologies that rely solely on frequency shifting or dynamic range compression often fail to comprehensively solve the problem, potentially leading to degraded sound quality or inability to adapt to environmental changes. This is mainly manifested in high latency, poor feedback suppression, and noise loss to the original audio.

[0004] First, traditional feedback suppression methods typically operate at relatively low sampling rates, resulting in relatively high latency. This is particularly pronounced in real-time audio applications, such as real-time communication or live performances, where high latency significantly impacts audio quality and user experience. Second, many existing methods employ only a single technique, such as simple frequency shifting or dynamic range compression. These methods often fail to comprehensively address complex audio environments and varying feedback conditions, limiting the maximization of suppression effectiveness. Finally, in attempting to reduce feedback, some methods may over-compress the dynamic range or filter out critical frequency components, leading to a degraded sound quality, especially in musical performances or high-quality audio transmissions. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this application is to provide an audio codec device, method and system with feedback suppression function to solve the problems of high latency, poor feedback suppression effect and loss of original audio quality in existing feedback suppression technology.

[0006] To achieve the above and other related objectives, a first aspect of this application provides an audio codec device with feedback suppression function, comprising: an analog-to-digital conversion unit electrically connected to a spectrum shifting unit; the analog-to-digital conversion unit is used to receive near-end audio analog signals and perform analog-to-digital conversion operations, data matching operations, and data buffering operations to generate corresponding near-end audio digital signals, and output the near-end audio digital signals to the spectrum shifting unit; the spectrum shifting unit is electrically connected to an automatic frequency control unit; the spectrum shifting unit includes an input terminal and an output terminal, the input terminal is used to input the near-end audio digital signals, and the output terminal is used to output the frequency-shifted signal obtained by the spectrum shifting unit to the automatic frequency control unit; the spectrum shifting unit is used to perform spectrum shifting operations on the near-end audio digital signals to generate the frequency-shifted signal; the automatic frequency control unit, The system is electrically connected to both the control interface and the audio interface. The automatic frequency control unit includes two input terminals and one output terminal. The two input terminals receive a frequency shift signal sent by the spectrum shifting unit and control information sent by the control interface, respectively. The output terminal outputs a feedback suppression signal obtained by the automatic frequency control unit to the audio interface. The automatic frequency control unit performs automatic frequency control operations on the frequency shift signal to generate the feedback suppression signal. A dynamic compression and limiting unit is electrically connected to the audio interface. The dynamic compression and limiting unit includes one input terminal and one output terminal. The input terminal receives a remote audio digital signal from the audio interface, and the output terminal outputs a howling suppression signal obtained after compression and limiting operations to the digital-to-analog converter. The dynamic compression and limiting unit performs compression and limiting operations on the remote audio digital signal to generate the howling suppression signal.

[0007] In some embodiments of the first aspect of this application, the process of the spectrum shifting unit performing spectrum shifting operation includes: receiving a near-end audio digital signal containing one or more channels sent by the analog-to-digital conversion unit; and performing a spectrum shifting operation sequentially on each channel of the near-end audio digital signal based on a preset spectrum shifting function to generate a frequency-shifted signal.

[0008] In some embodiments of the first aspect of this application, the automatic frequency control unit includes an adaptive filter. The process by which the automatic frequency control unit performs automatic frequency control operations through the adaptive filter includes: receiving the frequency shift signal sent by the spectrum shifting unit; receiving control information including a step size parameter sent by the control interface; performing a filtering operation on the frequency shift signal based on the filter parameters of the adaptive filter to generate a feedback suppression signal; calculating an error signal of the feedback suppression signal based on a preset no-feedback signal; and updating the filter parameters based on the error signal, the frequency shift signal, and the step size parameter.

[0009] In some embodiments of the first aspect of this application, the dynamic compression and limiting unit includes: a frequency domain decomposition module: configured to perform a frequency domain decomposition operation on the received remote audio digital signal according to a preset frequency band to generate a frequency band signal of multiple frequency bands, and send the frequency band signal of multiple frequency bands to the dynamic compression module; a dynamic compression module: configured to receive the frequency band signal containing multiple frequency bands sent by the dynamic compression module, perform a dynamic compression operation on the frequency band signal to generate a compressed frequency band signal and send it to the limiting processing module; a limiting processing module: configured to receive the compressed frequency band signal sent by the dynamic compression module, perform a limiting operation on the compressed frequency band signal to generate a limited frequency band signal and send it to the reconstruction and inverse transformation module; and a reconstruction and inverse transformation module: configured to receive the limited frequency band signal sent by the limiting processing module, perform a reconstruction operation and an inverse transformation operation on the limited frequency band signal to generate a howling suppression signal and send it to the digital-to-analog conversion unit.

[0010] In some embodiments of the first aspect of this application, the frequency domain decomposition module performs the frequency domain decomposition operation by: receiving a remote audio digital signal sent by an automatic frequency control unit; converting the remote audio digital signal from the time domain to the frequency domain by a fast Fourier transform; and performing spectral decomposition on the remote audio digital signal in the frequency domain in multiple preset frequency bands to generate a frequency band signal containing multiple frequency bands.

[0011] In some embodiments of the first aspect of this application, the process of the dynamic compression module performing dynamic compression includes: receiving a frequency band signal containing multiple frequency bands sent by the dynamic compression module; extracting and judging the dynamic energy range of each frequency band signal from the frequency band signal containing multiple frequency bands; if the dynamic energy range is less than or equal to the dynamic compression threshold, then no dynamic compression operation is performed and the frequency band signal is directly sent to the limiting frequency band signal as the limiting frequency band signal; otherwise, according to the dynamic compression threshold and a preset compression ratio, forward compression operation and reverse compression operation are performed on the frequency band signal containing multiple frequency bands respectively to generate the limiting frequency band signal and send it to the limiting processing module.

[0012] In some embodiments of the first aspect of this application, the process of the recombination and inverse transformation module performing recombination and inverse transformation operations includes: receiving a signal containing multiple frequency bands sent by the dynamic compression module and performing a signal recombination operation on it, and converting the recombined signal from the frequency domain to the time domain through an inverse Fourier transform to generate a howling suppression signal after howling suppression processing.

[0013] In some embodiments of the first aspect of this application, the digital-to-analog conversion unit is used to receive a remote audio digital signal sent by a data interface, and to perform data buffering operation, data matching operation, mixing operation and digital-to-analog conversion operation on the remote audio digital signal.

[0014] To achieve the above and other related objectives, a second aspect of this application provides an audio codec method with feedback suppression functionality, applied to an audio codec. The audio codec includes an audio interface and a control interface. The process of the audio codec performing feedback suppression includes: receiving a near-end analog audio signal and performing analog-to-digital conversion, data matching, and data buffering operations to generate a corresponding near-end digital audio signal; performing a spectrum shifting operation on the near-end digital audio signal to generate the frequency shift signal; receiving control information sent by the control interface and performing automatic frequency control on the frequency shift signal based on the control information to generate the feedback suppression signal and sending it to the audio interface; receiving a far-end digital audio signal and performing compression and limiting operations on the far-end digital audio signal to generate the feedback suppression signal.

[0015] To achieve the above and other related objectives, a third aspect of this application provides an audio codec system with feedback suppression function, comprising: a main processor and the aforementioned audio codec device with feedback suppression function.

[0016] As described above, the audio codec apparatus, method, and system with feedback suppression function in the field of audio codecs of this application have the following beneficial effects: Integrating the feedback suppression method into the audio codec increases the sampling rate of the automatic frequency algorithm, and processing the frequency domain signal increases the accuracy of the algorithm, while also significantly reducing the latency of feedback suppression, thereby providing a smoother audio experience. By adding adaptive feedback cancellation, frequency shifting, dynamic range compression, and limiting operations, the feedback problem can be effectively solved while maintaining sound quality. Furthermore, the intelligent algorithms in each module can adaptively adjust parameters according to the audio environment, enabling stable suppression of feedback phenomena in both static and dynamic scenarios. Attached Figure Description

[0017] Figure 1This illustration shows a schematic diagram of the external connections in one embodiment of the audio codec device with feedback suppression function according to this application.

[0018] Figure 2 This diagram shows a schematic diagram of the internal connections in one embodiment of the audio codec device with feedback suppression function according to this application.

[0019] Figure 3 This paper shows a schematic diagram of the analog-to-digital conversion unit in one embodiment of the audio codec device with feedback suppression function according to this application.

[0020] Figure 4 The diagram shows a schematic of the structure of the dynamic compression and limiting unit in one embodiment of the audio codec device with feedback suppression function of this application.

[0021] Figure 5 This paper shows a schematic diagram of the structure of a digital-to-analog converter unit in one embodiment of the audio codec device with feedback suppression function according to this application.

[0022] Figure 6 The diagram shows a flowchart of an embodiment of the audio encoding / decoding method with feedback suppression function according to this application.

[0023] Figure 7 This diagram illustrates the internal interaction flow of an embodiment of the audio codec system with feedback suppression function according to this application. Detailed Implementation

[0024] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0025] It should be noted that in the following description, reference is made to the accompanying drawings, which illustrate several embodiments of this application. It should be understood that other embodiments may also be used, and changes in mechanical composition, structure, electrical system, and operation may be made without departing from the spirit and scope of this application. The following detailed description should not be considered limiting, and the scope of the embodiments of this application is defined only by the claims of the published patent. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. Spatially related terms, such as “upper,” “lower,” “left,” “right,” “below,” “below,” “lower part,” “above,” “upper part,” etc., may be used herein to illustrate the relationship between one element or feature shown in the figures and another element or feature.

[0026] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," and "holding" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of the stated feature, operation, element, component, item, kind, and / or group, but do not preclude the presence, occurrence, or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition arise only when combinations of elements, functions, or operations are inherently mutually exclusive in some manner.

[0028] To address the problems described in the background section, this invention provides an audio codec device, method, and system with feedback suppression functionality. The aim is to solve the problems of high latency, poor feedback suppression effect, and loss of original audio quality inherent in existing feedback suppression technologies. Furthermore, to make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention are further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] Before providing a further detailed description of the present invention, the nouns and terms used in the embodiments of the present invention are explained, and the nouns and terms used in the embodiments of the present invention are subject to the following interpretations:

[0030] <1> Feedback suppression: Techniques used to reduce or eliminate feedback or echoes in audio systems.

[0031] <2> Audio codec: A device used to convert analog audio signals into digital signals (encoding) or digital signals into analog audio signals (decoding).

[0032] <3> Spectrum shifting: a technique used to change the spectral characteristics of a signal, typically used in applications such as signal compression, frequency conversion, or modulation and demodulation.

[0033] <4> Automatic frequency control: A control system used to automatically adjust the frequency of equipment or systems to ensure that they can maintain a stable working state under specific conditions.

[0034] This invention provides an audio codec apparatus with feedback suppression function, an audio codec method with feedback suppression function, and an audio codec system with feedback suppression function applied thereto. Regarding the structure of the audio codec apparatus with feedback suppression function, this invention will describe exemplary implementation scenarios of the audio codec apparatus with feedback suppression function.

[0035] like Figure 1 The diagram shows a schematic of the external connection structure of an audio codec device with feedback suppression function according to an embodiment of the present invention. It should be noted that the audio codec device with feedback suppression function involved in the present invention is located at... Figure 1 The audio codec shown internally connects to the main processor via control and data interfaces. It also takes near-end audio signals as input and outputs far-end audio signals.

[0036] In one embodiment of the present invention, an audio codec is a device used to encode / decode audio data, reducing data computation, transmission, and storage costs by converting audio data from one format to another. Its basic structure includes an uplink path, a downlink path, and a control interface. The first part is the uplink (recording) path, including an analog-to-digital conversion unit, a data format conversion unit, a data buffer unit, and a data interface. The second part is the downlink (playback) path, including a data buffer unit, a data format conversion unit, a mixing unit (multiple audio streams), and a digital-to-analog conversion unit. This embodiment also includes a feedback suppression control unit. This includes an Automatic Frequency Control (AFC) unit and a spectrum shifting unit located in the uplink path, and a dynamic compression and limiting unit located in the downlink path.

[0037] In one embodiment of the present invention, a System-on-Chip (SOC) processing chip is included, but is not limited to, for handling the main control functions of the device. This chip receives and processes the uplink audio data from the audio codec, transmits the audio data to the downlink channel of the audio codec, and performs further processing. Simultaneously, the main processor analyzes the data fed back from the audio codec and, based on the analysis results, sends parameter configurations to the AFC module in the audio codec via a control interface to control the howling suppression process within the audio codec.

[0038] Furthermore, the control interface is the channel through which the main processor sends commands to the audio codec. The interface protocols used include, but are not limited to, I2C, Soundwire, Slimbus, and HDA protocols. Through the control interface, the feedback suppression process of the audio codec can be controlled.

[0039] In one embodiment of the present invention, the audio interface (data interface) serves as a channel for audio data interaction between the main processor and the audio codec. Specifically, the audio codec sends the raw audio stream to the main processor through the audio interface, and simultaneously receives remote audio signals or local music signals sent by the main processor through the audio interface. The protocols used by the audio interface include, but are not limited to, I2S / PCM / TDM protocols, Soundwire protocols, Slimbus protocols, HDA protocols, and other interface protocols.

[0040] In one embodiment of the present invention, the audio input is an audio acquisition device that obtains an audio stream from external space using an audio codec. The audio acquisition device used includes, but is not limited to, digital microphones, analog microphones, sensors, or other forms of acoustic-to-electrical conversion devices. For the purposes of this invention, the audio input can be a single-channel signal or a multi-channel signal. The module performs the function of converting the acoustic signal into an electrical signal. Its input is a sound wave signal, and its output is a voltage signal.

[0041] In one embodiment of the present invention, the audio output refers to the audio codec outputting the audio stream to an external sound playback device, wherein the sound playback device includes, but is not limited to, one or more combinations of a handset, speaker, or headphones. The acquired near-end audio signal is a single-channel signal or a multi-channel signal, to achieve the function of converting electrical signals into sound signals. Its input is a voltage signal, and its output is a sound wave signal.

[0042] The external connection structure of the audio codec device with feedback suppression function provided in the embodiments of the present invention has been explained above. The internal structure of the audio codec device with feedback suppression function will be described in detail below.

[0043] In one embodiment of the present invention, an audio codec device with feedback suppression function includes: an analog-to-digital conversion unit electrically connected to a spectrum shifting unit; the analog-to-digital conversion unit is used to receive near-end audio analog signals and perform analog-to-digital conversion, data matching, and data buffering operations to generate corresponding near-end audio digital signals, and output the near-end audio digital signals to the spectrum shifting unit; the spectrum shifting unit is electrically connected to an automatic frequency control unit; the spectrum shifting unit includes an input terminal and an output terminal, the input terminal is used to input the near-end audio digital signals, and the output terminal is used to output the frequency shifted signal obtained by the spectrum shifting unit to the automatic frequency control unit; the spectrum shifting unit is used to perform spectrum shifting operations on the near-end audio digital signals to generate the frequency shifted signals; the automatic frequency control unit is connected to a control interface and an audio interface. Electrically connected to the audio interface; the automatic frequency control unit includes two input terminals and one output terminal. The two input terminals respectively input the frequency shift signal sent by the spectrum shift unit and the control information sent by the control interface. The output terminal is used to output the feedback suppression signal obtained by the automatic frequency control unit to the audio interface. The automatic frequency control unit is used to perform automatic frequency control operation on the frequency shift signal to generate the feedback suppression signal. Dynamic compression and limiting unit: electrically connected to the audio interface; the dynamic compression and limiting unit includes one input terminal and one output terminal. The input terminal is used to input the remote audio digital signal from the audio interface. The output terminal is used to output the howling suppression signal obtained by the compression and limiting operation to the digital-to-analog converter unit. The dynamic compression and limiting unit performs compression and limiting operation on the remote audio digital signal to generate the howling suppression signal.

[0044] Figure 2 A schematic diagram illustrating the internal structure of an audio / video codec according to an embodiment of the present invention is shown. Figure 2 As shown, the audio codec device with feedback suppression function includes an audio signal input and processing section and an audio signal output section. The input and processing section includes the following structures: an analog-to-digital conversion unit, a spectrum shifting unit, and an automatic frequency control (AFC) unit. The output section includes the following structures: a dynamic compression and limiting unit and a digital-to-analog conversion unit.

[0045] like Figure 3 The diagram illustrates the structure of an analog-to-digital conversion unit according to an embodiment of the present invention. The analog-to-digital conversion unit converts external audio input signals into digital signals that meet the processing requirements of the current system. It comprises three sub-modules: an analog-to-digital conversion module and a data buffer module. The input signal of this unit is an audio input signal (analog audio signal), and the output is a digital signal that meets the processing requirements of the current system. Its input signal can be a single-channel signal or a multi-channel signal, and the number of channels in the output signal is the same as the number of channels in the input signal.

[0046] In an embodiment of the present invention, the above analog-to-digital conversion module collects the analog audio stream input by the audio, and through sampling and quantization, converts it into a digital audio stream, so that subsequent processing is based on digital discrete signals. The analog-to-digital conversion module includes a sampling process and a quantization process. Among them, the sampling process is shown in Formula 1, and the quantization process is shown in Formula 2.

[0047] x(n) = x(nT), -∞ < n < ∞ (Formula 1)

[0048] x q (n) = Q[x(n)] (Formula 2)

[0049] As shown in Formula 1, the input analog continuous signal x(t) is discretely sampled at the sampling period T, and x(n) is output; subsequently, as shown in Formula 2, the output x(n) of the sampling process is discretized in amplitude by the quantization function Q, and x q (n) is output. Through the above two processes, the analog continuous signal is converted into the output digital discrete signal. The input of this module is a multi-channel audio input signal (analog audio signal), and the output is an intermediate analog-to-digital signal of the digital signal. Subsequently, the intermediate analog-to-digital signal of the output digital signal is sent to the data matching module.

[0050] In an embodiment of the present invention, after receiving the intermediate analog-to-digital signal, the data matching module performs a sampling rate matching operation and a signal bit width matching operation on it. Formulas 3 and 4 show the process of the data matching module performing filtering and sampling rate transformation on the intermediate analog-to-digital signal. Among them, x(n) is the output of the analog-to-digital conversion module, M is the downsampling change factor, I is the upsampling change factor, h(k) is the unit impulse response function, and the output y d (n) or y u (n).

[0051]

[0052]

[0053] Formula 5 shows the process of performing a signal bit width matching operation on the output y d (n) or y u (n). According to the positive or negative of the shift bit width B, a left shift amplification bit width matching or a right shift reduction bit width matching is performed, and the signal y m after the bit width matching operation is sent to the data cache module.

[0054]

[0055] In one embodiment of the present invention, a data caching module is used to cache a certain amount of data at the audio interface, thereby avoiding repeated sampling or loss of audio data due to jitter caused by design flaws in the system clocks on both sides of the interface. The input of this module is a digital signal, and there is no output data stream.

[0056] The above text combines Figure 3 The analog-to-digital conversion unit in an audio codec with feedback suppression function has been described in detail. The spectrum shifting unit and the automatic frequency control (AFC) unit will be described below.

[0057] In one embodiment of the present invention, the process of the spectrum shifting unit performing spectrum shifting operation includes: receiving a near-end audio digital signal containing one or more channels sent by the analog-to-digital conversion unit; and performing a spectrum shifting operation sequentially on each channel of the near-end audio digital signal based on a preset spectrum shifting function to generate a frequency-shifted signal.

[0058] In one embodiment of the present invention, the aforementioned spectrum shifting unit is used to prevent and reduce feedback problems in a public address system. Feedback problems arise from high-frequency echoes or resonances in the audio system, and are caused by high-intensity noise generated by feedback loops, particularly when a microphone captures and re-amplifies the speaker's output. By slightly altering the frequency of the audio signal, the audio feedback loop is broken, thus eliminating feedback loops that may cause feedback. The advantage of the spectrum shifting unit is that it can effectively reduce feedback without significantly affecting sound quality.

[0059] Furthermore, when the original input signal of the spectrum shifting unit is x o Equation 6 illustrates the process by which the spectrum shifting unit applies a constant frequency offset to the signal to achieve spectrum shifting.

[0060] x(n)=x o (n)·e jΔωn (Formula 6)

[0061] Where x(n) is the frequency-shifted signal after spectral shifting, e jΔωn The frequency shift is a complex exponential function, where Δω is the frequency offset and j is the imaginary unit. The input to the frequency shifting unit is a digital signal, and the output is a frequency-shifted signal. The input and output can be single-channel or multi-channel. When the input signal contains multiple channels, the frequency shifting operation described above is performed for each channel of the input signal.

[0062] In one embodiment of the present invention, the automatic frequency control unit includes an adaptive filter. The process by which the automatic frequency control unit performs automatic frequency control operation through the adaptive filter includes: receiving the frequency shift signal sent by the spectrum shifting unit; receiving the control information including step size parameters sent by the control interface; performing a filtering operation on the frequency shift signal based on the filter parameters of the adaptive filter to generate a feedback suppression signal; calculating the error signal of the feedback suppression signal based on a preset no-feedback signal; and updating the filter parameters based on the error signal, the frequency shift signal, and the step size parameters.

[0063] In one embodiment of the present invention, the aforementioned Automatic Frequency Control (AFC) unit is used to monitor the input frequency shift signal and analyze the audio signal in real time to identify and eliminate feedback loops that may cause howling. The AFC unit automatically learns and adapts to changes in the audio environment by constructing a mathematical model simulating the audio environment, continuously adjusts the mathematical model, and generates howling processing strategies to reduce or eliminate the generated howling.

[0064] Specifically, the frequency control process of the Automatic Frequency Control (AFC) unit includes: when the frequency shift signal input to the AFC unit is x(n), the process of feedback loop elimination of the frequency shift signal using a filter with an impulse response coefficient of w(n) is shown in Formula 7, where M is the length of the filter.

[0065]

[0066] The calculation process of the filter error signal in the AFC unit is shown in Equation 8. d(n) represents the signal without feedback, where the output signal... When the frequency shift is equal to the input signal, That is, there is no feedback signal d(n).

[0067]

[0068] The process of updating the impulse response coefficients based on the error signal of the filter in the AFC unit using the least mean square (LMS) algorithm is shown in Equation 9.

[0069] w(n+1)=w(n)+μ·e(n)·x(n) (Formula 9)

[0070] Here, x(n) contains a vector of the current and past M-1 input samples, and μ is the update step size parameter used to update the impulse response coefficients.

[0071] In this embodiment, the input to the AFC unit is a frequency shift signal, and the output is a feedback suppression signal. Both the input and output signals can be single-channel or multi-channel signals. When the input signal is a multi-channel signal, the aforementioned automatic frequency control operation is performed sequentially on each channel's signal.

[0072] The preceding text has explained the uplink path of an audio codec with feedback suppression functionality through several embodiments, including a detailed description of the connection structure and working principle of the analog-to-digital conversion unit, the spectrum shifting unit, and the automatic frequency control unit. The following text will describe the downlink path of the audio codec with feedback suppression functionality in conjunction with embodiments.

[0073] The downlink path receives the remote audio digital signal from the main processor via the data interface and audio interface, and then sequentially inputs it to the dynamic compression and limiting unit and the digital-to-analog converter unit to generate the remote audio analog signal, which is then output to an external audio playback device for playback. The internal structure and working principle of the dynamic compression and limiting unit and the digital-to-analog converter unit will be further explained below.

[0074] In one embodiment of the present invention, the dynamic compression and limiting unit includes: a frequency domain decomposition module: used to perform frequency domain decomposition operation on the received far-end audio digital signal according to a preset frequency band to generate a frequency band signal of multiple frequency bands, and send the frequency band signal of multiple frequency bands to the dynamic compression module; a dynamic compression module: used to receive the frequency band signal containing multiple frequency bands sent by the dynamic compression module, perform dynamic compression operation on the frequency band signal to generate a compressed frequency band signal and send it to the limiting processing module; a limiting processing module: used to receive the compressed frequency band signal sent by the dynamic compression module, perform a limiting operation on the compressed frequency band signal to generate a limited frequency band signal and send it to the reconstruction and inverse transformation module; and a reconstruction and inverse transformation module: used to receive the limited frequency band signal sent by the limiting processing module, perform reconstruction and inverse transformation operation on the limited frequency band signal to generate a howling suppression signal and send it to the digital-to-analog conversion unit.

[0075] Furthermore, the frequency domain decomposition module performs the frequency domain decomposition operation by: receiving the remote audio digital signal sent by the automatic frequency control unit; converting the remote audio digital signal from the time domain to the frequency domain through a fast Fourier transform; and performing spectral decomposition on the remote audio digital signal in the frequency domain in multiple preset frequency bands to generate a frequency band signal containing multiple frequency bands.

[0076] In this embodiment, the process of the dynamic compression module performing dynamic compression includes: receiving a frequency band signal containing multiple frequency bands sent by the dynamic compression module; extracting and judging the dynamic energy range of each frequency band signal from the frequency band signal containing multiple frequency bands; if the dynamic energy range is less than or equal to the dynamic compression threshold, then no dynamic compression operation is performed and the frequency band signal is directly sent to the limiting frequency band signal as the limiting frequency band signal; otherwise, according to the dynamic compression threshold and a preset compression ratio, forward compression operation and reverse compression operation are performed on the frequency band signal containing multiple frequency bands respectively to generate the limiting frequency band signal and send it to the limiting processing module.

[0077] Furthermore, the process of the recombination and inverse transformation module performing recombination and inverse transformation operations includes: receiving signals containing multiple frequency bands sent by the dynamic compression module and performing signal recombination operations on them, and converting the recombined signal from the frequency domain to the time domain through inverse Fourier transform to generate a howling suppression signal after howling suppression processing.

[0078] Figure 4 A schematic diagram of a dynamic compression and limiting unit according to an embodiment of the present invention is shown. The dynamic compression and limiting unit includes a frequency domain analysis module, a dynamic compression module, a limiting processing module, and a reconstruction and inverse transform module. The frequency domain analysis module performs a frequency domain decomposition operation to decompose the far-end frequency domain signal into multiple preset frequency bands.

[0079] In this embodiment, the frequency domain decomposition operation includes the following process: first, the input far-end audio signal x(t) is converted from the time domain to the frequency domain using Fast Fourier Transform (FFT), as shown in Equation 10.

[0080] X(f) = FFT(x(t)) (Formula 10)

[0081] Where X(f) is the frequency domain representation of the signal, f is the frequency, and then the spectrum X(f) is further decomposed into N different frequency bands using Equation 11.

[0082]

[0083] Where each X i (f) represents the i-th specific frequency band, which contains a total of N specific frequency bands.

[0084] In this embodiment, the dynamic compression operation includes the following process: based on the compression threshold and dynamic energy range, for the frequency band signals X of N specific frequency bands obtained from the frequency domain decomposition operation... i (f) Make judgments respectively, and perform the corresponding positive compression operation, negative compression operation or no compression operation according to the judgment results.

[0085] For the input i-th frequency band signal X i (f), whose corresponding compression threshold is T c,i For X i (f) and T c,i Make a judgment: If |X i (f)|≤T c,i If no compression operation is performed, the input signal is directly input and the output signal Y is output. c,i (f) As shown in Formula 12.

[0086] Y c,i (f)=X i (f)(Formula 12)

[0087] When X i (f)>T c,i When, for the input i-th frequency band signal X i (f) Perform a forward compression operation, that is, the output signal is forward compressed, as shown in Equation 13.

[0088]

[0089] Among them, T c,i R is the compression threshold. c,i This represents the compression ratio.

[0090] When X i (f) <T c,i When, for the input i-th frequency band signal X i (f) Perform a negative compression operation, that is, the output signal is negatively compressed, as shown in Equation 14.

[0091]

[0092] In this embodiment, the process of performing amplitude limiting on the dynamically compressed signal includes performing amplitude limiting operation for each frequency band i using an amplitude limiting threshold, as shown in Formula 15.

[0093] Y l,i (f)=min(max(Y c,i (f),-T l,i ),T l,i )(Formula 15)

[0094] Where T l,i It is the amplitude limiting threshold for the i-th frequency band.

[0095] In this embodiment, the processed signals of each frequency band are recombined and inversely transformed as shown in Formula 16.

[0096]

[0097] The signal is then converted back from the frequency domain to the time domain using the inverse fast Fourier transform (IFFT), as shown in Equation 17.

[0098] y(t)=IFFT(Y(f))(Formula 17)

[0099] Where y(t) is the final output dynamic compressed digital signal after frequency domain processing.

[0100] The above text combined Figure 4 The dynamic compression and limiting unit is described in detail below, and will be discussed in conjunction with the following text. Figure 5 The digital-to-analog converter unit connected to the audio output terminal in this invention will be described in detail.

[0101] In one embodiment of the present invention, the digital-to-analog conversion unit is used to receive the remote audio digital signal sent by the data interface, and perform data buffering operation, data matching operation, mixing operation and digital-to-analog conversion operation on the remote audio digital signal.

[0102] Figure 5 A schematic diagram of a digital-to-analog conversion unit according to an embodiment of the present invention is shown. The digital-to-analog conversion unit includes a data buffer module, a data matching module, a mixing module, and a digital-to-analog conversion module. The digital-to-analog conversion unit is used to convert digital signals into audio output signals, i.e., remote audio analog signals. The input signal of this module is a dynamically compressed digital signal, and the output is an audio output signal (usually an analog signal). The input signal of this unit can be a single-channel signal or a multi-channel signal, and the output signal is the corresponding single-channel signal or multi-channel signal. Since the mixing module may modify the number of channels of the signal, the number of channels of the input signal and the output signal do not necessarily have to be the same.

[0103] In this embodiment, the data caching module is used to cache a certain amount of data at the audio interface, thereby avoiding jitter caused by design flaws in the system clocks on both sides of the interface, which could lead to repeated sampling or loss of audio data. After receiving the remote audio digital signal, the data matching module performs sampling rate matching and signal bit width matching operations to match the preset parameters of the audio output device and generate an intermediate digital-to-analog signal.

[0104] In this embodiment, the mixing module mixes and superimposes multiple downlink audio streams, such as the remote audio digital signal transmitted by the audio codec main processor through the data interface or the locally stored audio stream, as shown in Formula 18.

[0105]

[0106] Where M is the number of input audio streams, x k(n) represents the k-th input audio stream. The output mixed audio stream y(n) is obtained by accumulating the input remote audio digital signals.

[0107] In this embodiment, the digital-to-analog conversion module is used to convert the mixed signal obtained after mixing from a digital signal to an analog signal for output by the audio output device, as shown in Formulas 19 and 20.

[0108]

[0109] v = ky(t) (Formula 20)

[0110] Equation 19 illustrates the interpolation process, where the digital-to-analog converter increases the sampling rate of the input audio to a preset output sampling rate through interpolation, and performs interpolation fitting between digital samples. Equation 20 illustrates the process of converting a digital signal into an analog signal, where y(n) is the input discrete digital signal, k is a scaling factor, and the output analog voltage signal is v(t), thus realizing the conversion of a discrete digital signal into a continuous analog signal.

[0111] like Figure 6 The diagram illustrates a flowchart of an audio codec method with feedback suppression functionality according to an embodiment of the present invention. The audio codec method with feedback suppression functionality in this embodiment mainly includes the following steps:

[0112] S61: Receives near-end audio analog signals and performs analog-to-digital conversion, data matching, and data buffering operations to generate corresponding near-end audio digital signals.

[0113] S62: Perform a spectrum shifting operation on the near-end audio digital signal to generate the frequency shift signal.

[0114] S63: Receive control information sent by the control interface, and perform automatic frequency control operation on the frequency shift signal based on the control information to generate the feedback suppression signal and send it to the audio interface.

[0115] S64: Receive a remote audio digital signal and perform compression and limiting operations on the remote audio digital signal to generate a howling suppression signal.

[0116] like Figure 7 The diagram illustrates the structure of an audio codec system with feedback suppression function according to an embodiment of the present invention. In this embodiment, the audio codec system 700 with feedback suppression function includes a main processor 701 and the aforementioned audio codec device 702 with feedback suppression function.

[0117] It should be noted that the audio codec system with feedback suppression function provided in the above embodiments is only illustrated by the division of the above program modules. In practical applications, the above processing can be assigned to different program modules as needed, that is, the internal structure of the system can be divided into different program modules to complete all or part of the processing described above. In addition, the audio codec system with feedback suppression function provided in the above embodiments and the audio codec method embodiment with feedback suppression function belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0118] In summary, this application provides an audio codec apparatus, method, and system with feedback suppression functionality. This invention provides a method for feedback suppression via an audio codec. By integrating the feedback suppression function within the audio codec and incorporating a spectrum shifting unit and an automatic frequency control unit in the uplink path of the audio codec, while simultaneously incorporating a dynamic compression and limiting unit in the downlink path, the synergistic effect of these units reduces the feedback suppression delay time. This allows for flexible adaptation to various acoustic environments and feedback types while maintaining sound quality. Furthermore, algorithms can be used to perform corresponding feedback suppression operations on the input near-end audio signal to adapt to dynamic changes in feedback suppression scenarios, while maintaining consistency in sound quality and volume, avoiding loss of original audio quality. This application effectively overcomes various shortcomings of existing technologies and possesses high industrial applicability.

[0119] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. An audio codec device with feedback suppression function, characterized in that, include: The analog-to-digital conversion unit is electrically connected to the spectrum shifting unit; The analog-to-digital conversion unit is used to receive near-end audio analog signals and perform analog-to-digital conversion, data matching, and data buffering operations to generate corresponding near-end audio digital signals, and output the near-end audio digital signals to the spectrum shifting unit. A spectrum shifting unit is electrically connected to an automatic frequency control unit. The spectrum shifting unit includes an input terminal and an output terminal. The input terminal is used to input a near-end audio digital signal, and the output terminal is used to output the frequency-shifted signal obtained by the spectrum shifting unit to the automatic frequency control unit. The spectrum shifting unit is used to perform a spectrum shifting operation on the near-end audio digital signal to generate the frequency-shifted signal. An automatic frequency control unit is electrically connected to a control interface and an audio interface. The automatic frequency control unit includes two input terminals and one output terminal. The two input terminals respectively receive a frequency shift signal sent by a spectrum shifting unit and control information sent by the control interface. The output terminal is used to output a feedback suppression signal obtained by the automatic frequency control unit to the audio interface. The automatic frequency control unit is used to perform automatic frequency control operations on the frequency shift signal to generate the feedback suppression signal. Dynamic compression and limiting unit: electrically connected to the audio interface; the dynamic compression and limiting unit includes an input terminal and an output terminal, the input terminal is used to input a remote audio digital signal from the audio interface, and the output terminal is used to output the feedback suppression signal obtained by compression and limiting operation to the digital-to-analog converter unit; the dynamic compression and limiting unit performs compression and limiting operation on the remote audio digital signal to generate the feedback suppression signal.

2. The audio codec device with feedback suppression function according to claim 1, characterized in that, The process by which the spectrum shifting unit performs the spectrum shifting operation includes: Receives a near-end audio digital signal containing one or more channels sent by the analog-to-digital conversion unit; Based on a preset spectrum shifting function, a spectrum shifting operation is sequentially performed on each channel of the near-end audio digital signal to generate a frequency-shifted signal.

3. The audio codec device with feedback suppression function according to claim 1, characterized in that, The automatic frequency control unit includes an adaptive filter, and the process by which the automatic frequency control unit performs automatic frequency control operations through the adaptive filter includes: Receive the frequency shift signal sent by the frequency shifting unit; Receive the control information containing the step size parameter sent by the control interface; Based on the filter parameters of the adaptive filter, a filtering operation is performed on the frequency-shifted signal to generate a feedback suppression signal; Based on a preset no-feedback signal, calculate the error signal of the feedback suppression signal; The filter parameters are updated based on the error signal, the frequency shift signal, and the step size parameter.

4. The audio codec device with feedback suppression function according to claim 1, characterized in that, The dynamic compression and limiting unit includes: Frequency domain decomposition module: used to perform frequency domain decomposition operation on the received remote audio digital signal according to the preset frequency band to generate frequency band signals of multiple frequency bands, and send the frequency band signals of multiple frequency bands to the dynamic compression module; Dynamic compression module: used to receive frequency band signals containing multiple frequency bands sent by the dynamic compression module, perform dynamic compression operation on the frequency band signals to generate compressed frequency band signals and send them to the amplitude limiting processing module; Amplification limiting module: used to receive the compressed frequency band signal sent by the dynamic compression module, perform amplification limiting operation on the compressed frequency band signal to generate a limited frequency band signal and send it to the reconstruction and inverse transformation module; Reassembly and Inverse Transformation Module: Used to receive the limited frequency band signal sent by the limiting processing module, perform recombination and inverse transformation operations on the limited frequency band signal to generate a howling suppression signal and send it to the digital-to-analog conversion unit.

5. The audio codec device with feedback suppression function according to claim 4, characterized in that, The frequency domain decomposition module performs the frequency domain decomposition operation as follows: Receives remote audio digital signals sent by the automatic frequency control unit; The remote audio digital signal is converted from the time domain to the frequency domain using a fast Fourier transform. The frequency domain of the far-end audio digital signal is spectrally decomposed in multiple preset frequency bands to generate a frequency band signal containing multiple frequency bands.

6. The audio codec with feedback suppression function according to claim 4, characterized in that, The process by which the dynamic compression module performs dynamic compression operations includes: Receive frequency band signals containing multiple frequency bands sent by the dynamic compression module: Extract the dynamic energy range of each frequency band signal from a frequency band signal containing multiple frequency bands and make a judgment; If the dynamic energy range is less than or equal to the dynamic compression threshold, then the dynamic compression operation is not performed and the frequency band signal is directly sent to the limiting frequency band signal as the limiting frequency band signal. Otherwise, based on the dynamic compression threshold and the preset compression ratio, forward compression and reverse compression operations are performed on the frequency band signal containing multiple frequency bands respectively to generate the amplitude-limited frequency band signal and send it to the amplitude-limiting processing module.

7. The audio codec device with feedback suppression function according to claim 4, characterized in that, The process of the recombination and inverse transformation module performing recombination and inverse transformation operations includes: receiving signals containing multiple frequency bands sent by the dynamic compression module and performing signal recombination on them, and converting the recombined signal from the frequency domain to the time domain through inverse Fourier transform to generate a howling suppression signal after howling suppression processing.

8. The audio codec device with feedback suppression function according to claim 1, characterized in that, The digital-to-analog converter unit is used to receive remote audio digital signals sent by the data interface and perform data buffering, data matching, mixing, and digital-to-analog conversion operations on the remote audio digital signals.

9. An audio codec method with feedback suppression function, the method being implemented by an audio codec device with feedback suppression function as described in any one of claims 1 to 8, characterized in that, Applied to an audio codec, the audio codec including an audio interface and a control interface, the process of the audio codec performing howling suppression includes: It receives near-end audio analog signals and performs analog-to-digital conversion, data matching, and data buffering operations to generate corresponding near-end audio digital signals; Perform a spectrum shifting operation on the near-end audio digital signal to generate a frequency-shifted signal; The system receives control information sent by the control interface and performs automatic frequency control operation on the frequency shift signal based on the control information to generate a feedback suppression signal and send it to the audio interface. Receive a remote audio digital signal and perform compression and limiting operations on the remote audio digital signal to generate a howling suppression signal.

10. An audio codec system with feedback suppression function, characterized in that, include: The main processor and the audio codec device with feedback suppression function as described in any one of claims 1 to 8.

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