阅读说明：本技术 一种音频输入检测电路及方法 (Audio input detection circuit and method ) 是由 张琦 林艳华 舒倩 佘晨宇 徐威 于 2021-07-30 设计创作，主要内容包括：本发明实施例提供一种音频输入检测电路及方法。包括：音频输入端,用于外接音频输入装置；偏置电压模块,用于为音频输入装置供电；开关模块,位于偏置电压模块与音频输入端的连接通路上,用于在主控芯片的控制下导通连接通路或断开连接通路；主控芯片,根据连接通路导通时音频编解码模块采集的第一音频信号和连接通路断开时音频编解码模块采集的第二音频信号,确定音频输入装置为有源音频输入装置或无源音频输入装置。可以根据偏置电压模块通断两种情况下获得的音频信号的不同自动确定音频输入装置的类型,无需人工参与,提升了用户体验。而且,不需要额外增加音频处理和检测芯片,简单易实现且成本较低。(The embodiment of the invention provides an audio input detection circuit and an audio input detection method. The method comprises the following steps: the audio input end is used for being externally connected with an audio input device; the bias voltage module is used for supplying power to the audio input device; the switch module is positioned on a connecting path of the bias voltage module and the audio input end and used for switching on or switching off the connecting path under the control of the main control chip; and the main control chip determines that the audio input device is an active audio input device or a passive audio input device according to the first audio signal acquired by the audio coding and decoding module when the connecting channel is switched on and the second audio signal acquired by the audio coding and decoding module when the connecting channel is switched off. The type of the audio input device can be automatically determined according to the difference of the audio signals obtained under the two conditions of the on-off of the bias voltage module, manual participation is not needed, and the user experience is improved. In addition, an audio processing and detecting chip is not required to be additionally arranged, and the method is simple and easy to implement and low in cost.)

1. An audio input detection circuit, comprising:

the audio input end is used for being externally connected with an audio input device;

the bias voltage module is used for supplying power to the audio input device;

the switch module is positioned on a connection path of the bias voltage module and the audio input end and used for switching on or off the connection path under the control of the main control chip;

the audio encoding and decoding module is used for acquiring the audio signal output by the audio input end;

the main control chip is used for controlling the switch module and determining that the audio input device is an active audio input device or a passive audio input device according to a first audio signal acquired by the audio coding and decoding module when the connection path is switched on and a second audio signal acquired by the audio coding and decoding module when the connection path is switched off.

2. The circuit of claim 1, wherein the master control chip is specifically configured to:

when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined to be larger than the preset threshold value, determining that the audio input device is an active audio input device; or

And when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined not to be larger than the preset threshold value, determining that the audio input device is a passive audio input device.

3. The circuit of claim 1, wherein the circuit further comprises: a protection circuit on the connection path;

the protection circuit is used for preventing the voltage of the audio input device from influencing the bias voltage module.

4. The circuit of claim 1, wherein the circuit further comprises: the coupling module is positioned on an audio channel between the audio input device and the audio coding and decoding module;

the coupling module is used for filtering out direct current signals in the audio signals.

5. The circuit of claim 4, wherein the circuit further comprises: the signal conditioning module is positioned between the coupling module and the audio coding and decoding module;

and the signal conditioning module is used for filtering out-of-bandwidth noise in the audio signal and amplifying the filtered audio signal.

6. The circuit of claim 5,

the signal conditioning module comprises a band-pass filter circuit and a gain amplifying circuit.

7. The circuit of any one of claims 1-6, further comprising: an audio signal processing module;

the audio signal processing module is configured to process the audio signal according to a first gain mode when the main control chip determines that the audio input device is a passive audio input device.

8. The circuit of claim 7, wherein the audio signal processing module is further configured to process the audio signal according to a second gain mode when the main control chip determines that the audio input device is an active audio input device; the amplification degree of the first gain mode is greater than that of the second gain mode.

9. An audio input detection method, comprising:

the control switch module is used for conducting a connecting channel between the bias voltage module and the audio input end and collecting a first audio signal through the audio coding and decoding module;

controlling the switch module to disconnect the connecting path and acquiring a second audio signal through the audio coding and decoding module;

determining that the audio input device is an active audio input device or a passive audio input device according to the first audio signal and the second audio signal.

10. The method of claim 9, wherein determining that the audio input device is an active audio input device or a passive audio input device based on the first audio signal and the second audio signal comprises:

when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined to be larger than the preset threshold value, determining that the audio input device is an active audio input device; or

And when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined not to be larger than the preset threshold value, determining that the audio input device is a passive audio input device.

11. The method of claim 9, further comprising:

when the audio input device is determined to be a passive audio input device, processing the audio signal through an audio signal processing module according to a first gain mode;

when the audio input device is determined to be an active audio input device, processing the audio signal through the audio signal processing module according to a second gain mode; the amplification degree of the first gain mode is greater than that of the second gain mode.

Technical Field

The embodiment of the invention relates to the technical field of circuits, in particular to an audio input detection circuit and an audio input detection method.

Background

In the practical application of security monitoring, a client usually connects an external sound pickup on an audio input interface of monitoring equipment as an audio input source. The sound pick-up is divided into an active sound pick-up and a passive sound pick-up according to the existence or nonexistence of power supply. Due to differences in the circuits inside the microphones, the amplitude of the signal output by a passive microphone is often much lower than that output by an active microphone.

Based on the difference that different types of adapter exist, in order to guarantee the quality of output tone quality, a supervisory equipment can only connect the adapter of a corresponding type among the prior art, this application range that has greatly shortened supervisory equipment.

Therefore, the embodiment of the invention provides an audio input detection circuit, which is used for simply and effectively detecting the type of a sound pick-up externally connected with equipment.

Disclosure of Invention

The embodiment of the invention provides an audio input detection circuit, which is used for automatically and accurately detecting the type of an external audio input device.

In a first aspect, an embodiment of the present invention provides an audio input detection circuit, including:

the audio input end is used for being externally connected with an audio input device;

the bias voltage module is used for supplying power to the audio input device;

the switch module is positioned on a connection path of the bias voltage module and the audio input end and used for switching on or switching off the connection path under the control of the main control chip;

the audio encoding and decoding module is used for acquiring the audio signal output by the audio input end;

the main control chip is used for controlling the switch module and determining that the audio input device is an active audio input device or a passive audio input device according to a first audio signal acquired by the audio coding and decoding module when the connection path is switched on and a second audio signal acquired by the audio coding and decoding module when the connection path is switched off.

According to the embodiment of the invention, the characteristic that the audio signals have difference when the bias voltage module is switched on and switched off when the passive audio input device normally works is utilized, and the on-off of the bias voltage module is controlled by setting the switch module, so that the type of the audio input device is automatically determined according to the difference of the audio signals obtained under the two conditions of on-off, manual participation is not needed, and the user experience is improved. In addition, the existing audio coding and decoding module and the main control chip in the equipment circuit accessed by the audio input device can be used for detection, and no additional audio processing and detection chip is needed, so that the method is simple and easy to implement and has lower cost.

Optionally, the main control chip is specifically configured to:

when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined to be larger than the preset threshold value, determining that the audio input device is an active audio input device; or

And when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined not to be larger than the preset threshold value, determining that the audio input device is a passive audio input device.

When the bias voltage module is conducted, the audio input end is externally connected with an audio input device by determining that the amplitude of the first audio signal is larger than a preset threshold value; and judging the relation between the amplitude of the second audio signal obtained when the bias voltage module is disconnected and a preset threshold value, so that the type of the audio input device can be automatically determined. And the type of the audio input device is continuously detected in the next step under the condition that the audio input is detected for the first time, and the effect that the audio input device starts automatic detection when sound input is performed is achieved without manually starting the detection by a user.

Optionally, the circuit further comprises: a protection circuit on the connection path;

the protection circuit is used for preventing the voltage of the audio input device from influencing the bias voltage module.

Optionally, the circuit further comprises: the coupling module is positioned on an audio channel between the audio input device and the audio coding and decoding module;

the coupling module is used for filtering out direct current signals in the audio signals.

Optionally, the circuit further comprises: the signal conditioning module is positioned between the coupling module and the audio coding and decoding module;

and the signal conditioning module is used for filtering out-of-bandwidth noise in the audio signal and amplifying the filtered audio signal.

Optionally, the signal conditioning module includes a band-pass filter circuit and a gain amplifier circuit.

Optionally, the method further comprises: an audio signal processing module;

the audio signal processing module is configured to process the audio signal according to a first gain mode when the main control chip determines that the audio input device is a passive audio input device.

Optionally, the audio signal processing module is further configured to process the audio signal according to a second gain mode when the main control chip determines that the audio input device is an active audio input device; the amplification degree of the first gain mode is greater than that of the second gain mode.

After the type of the audio input device is determined, the corresponding gain can be automatically set according to the type of the audio input device, so that the quality of collected audio can be guaranteed when the equipment is connected to various audio input devices, the use diversity is increased, and the user experience is improved.

In a second aspect, an embodiment of the present invention further provides an audio input detection method, including:

the control switch module is used for conducting a connecting channel between the bias voltage module and the audio input end and collecting a first audio signal through the audio coding and decoding module;

controlling the switch module to disconnect the connecting path and acquiring a second audio signal through the audio coding and decoding module;

determining that the audio input device is an active audio input device or a passive audio input device according to the first audio signal and the second audio signal.

Optionally, determining that the audio input device is an active audio input device or a passive audio input device according to the first audio signal and the second audio signal includes:

when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined to be larger than the preset threshold value, determining that the audio input device is an active audio input device; or

And when the amplitude of the first audio signal is determined to be larger than a preset threshold value and the amplitude of the second audio signal is determined not to be larger than the preset threshold value, determining that the audio input device is a passive audio input device.

Optionally, the method further comprises:

when the audio input device is determined to be a passive audio input device, processing the audio signal through an audio signal processing module according to a first gain mode;

when the audio input device is determined to be an active audio input device, processing the audio signal through the audio signal processing module according to a second gain mode; the amplification degree of the first gain mode is greater than that of the second gain mode.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic diagram of a possible audio input detection circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a possible switch module according to an embodiment of the present invention;

FIG. 3 is a block diagram of an exemplary audio input detection method;

FIG. 4 is a schematic diagram of a possible audio input detection circuit according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a possible audio input detection circuit according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a possible audio input detection circuit according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a possible audio input detection circuit according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a possible audio input detection circuit according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a possible audio input detection circuit according to an embodiment of the present invention;

fig. 10 is a flowchart illustrating an audio input detection method according to an embodiment of the present invention.

Detailed Description

To make the objects, embodiments and advantages of the present application clearer, the following description of exemplary embodiments of the present application will clearly and completely describe the exemplary embodiments of the present application with reference to the accompanying drawings in the exemplary embodiments of the present application, and it is to be understood that the described exemplary embodiments are only a part of the embodiments of the present application, and not all of the embodiments.

All other embodiments, which can be derived by a person skilled in the art from the exemplary embodiments described herein without inventive step, are intended to be within the scope of the claims appended hereto. In addition, while the disclosure herein has been presented in terms of one or more exemplary examples, it should be appreciated that aspects of the disclosure may be implemented solely as a complete embodiment.

It should be noted that the brief descriptions of the terms in the present application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of the present application. These terms should be understood in their ordinary and customary meaning unless otherwise indicated.

The terms "first," "second," "third," and the like in the description and claims of this application and in the above-described drawings are used for distinguishing between similar or analogous objects or entities and are not necessarily intended to limit the order or sequence of any particular one, Unless otherwise indicated. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

Furthermore, the terms "comprises" and "comprising," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a product or device that comprises a list of elements is not necessarily limited to those elements explicitly listed, but may include other elements not expressly listed or inherent to such product or device. Fig. 1 schematically illustrates a possible audio input detection circuit provided by an embodiment of the present invention, which includes an audio input terminal, a bias voltage module, a switch module, an audio codec module, and a main control chip.

The detection circuit provided by the embodiment of the invention can be arranged in various devices which need to be externally connected with an audio input device, such as monitoring equipment, televisions, computers and the like. The following describes a detection circuit according to an embodiment of the present invention by taking a monitoring device as an example.

And the audio input end is used for being externally connected with an audio input device. The external audio input device is not limited in type, such as a passive sound pickup, an active sound pickup, and the like. Because the power supply mode is different, the passive sound pick-up does not have a power supply in the passive sound pick-up, so a bias voltage module of the passive sound pick-up is required to provide bias voltage for normal work, and because the passive sound pick-up does not have a gain amplification circuit in the passive sound pick-up, the amplitude of an output audio signal is also lower than that of an active sound pick-up. The active sound pick-up can be connected with an external power supply, so the active sound pick-up can work normally without bias voltage provided by equipment, a gain amplification circuit is usually arranged in the active sound pick-up, the signal output amplitude is larger, but because the active sound pick-up is connected with the external power supply, noise, particularly power supply noise, is easily introduced into the equipment.

And the bias voltage module is used for supplying power to the audio input device. The provided bias voltage is direct-current voltage, and when the bias voltage module is conducted, if the external audio input device is a passive audio input device, the passive audio input device can also work normally.

And the switch module is positioned on a connecting path of the bias voltage module and the audio input end and used for conducting the connecting path or disconnecting the connecting path under the control of the main control chip.

The specific circuit structure of the switch module is not limited in the embodiment of the present invention, and may be, for example, a switch chip, a connection path between the bias voltage module and the audio input terminal is conducted under the control of the main control chip, or may be a circuit structure of a switch module as illustrated in fig. 2.

In fig. 2, Q1 is a transistor, and the main control chip controls the transistor to be turned on and off through IO to control the switch module to be turned on and off. R2 is provided to provide a default initial state for the switch module. In order to ensure that the current flowing through the base of Q1 is not too large when the transistor is turned on, a protection resistor R1 may be provided. Meanwhile, in order to avoid that the bias voltage module supplies power to the audio input device through the branch where the R2 is located when the switch module is turned off, and because the bias voltage provided by the bias voltage module is a direct-current voltage, the capacitor C4 is provided to block the direct-current from passing through.

The above is only one possible circuit structure of the switch module, and those skilled in the art can make various designs for the circuit structure of the switch module, and in any case, the switch module capable of controlling the bias voltage module to supply/not supply power to the audio input device falls into the protection scope of the embodiment of the present invention.

And the audio coding and decoding module is used for collecting the audio signals output by the audio input end. The function of the audio encoding and decoding module can be realized by an encoding and decoding chip, and the design of the encoding and decoding chip is not limited by the embodiment of the invention.

The main control chip is used for controlling the switch module to be switched on and off, when the switch module is switched off, a connecting path between the bias voltage module and the audio input device is disconnected, and at the moment, the audio coding and decoding module collects a second audio signal; when the switch module is closed, the connection path between the bias voltage module and the audio input device is conducted, and at the moment, the audio coding and decoding module collects a first audio signal.

The main control chip determines that the audio input device is an active audio input device or a passive audio input device according to the first audio signal and the second audio signal. Two methods of determining an audio input device are provided below.

For example, a preset threshold may be set, and when the received signal is greater than the preset threshold, it is interpreted that there is a voice input. The value of the preset threshold may be determined by a person skilled in the art after performing experiments according to the structure of the circuit, the external environment, and the like, or may be determined empirically. Specifically, when the amplitude of the first audio signal is determined to be greater than the preset threshold, it is indicated that the audio input device is connected to the audio input terminal when the bias voltage module is turned on, and a sound is received through the audio input device. And then when the bias voltage module is disconnected, receiving a second audio signal, if the second audio signal is greater than a preset threshold value, indicating that the sound signal reaching the preset threshold value can still be received, indicating that the external device is an active audio input device, and if the second audio signal is not greater than the preset threshold value, indicating that the received sound signal is weak due to the absence of the bias voltage provided by the bias voltage module, indicating that the external device is a passive audio input device.

For another example, the type of the audio input device may be determined only by the first audio signal. The main control switch module is conducted, and the bias voltage provided by the bias voltage module is loaded on the audio input end. The method comprises the steps that a pressure sensor or a detection chip is arranged at an audio input end, when the fact that an audio input device is connected is detected, whether the signal amplitude of a first audio signal reaches a sound breaking threshold value is judged, and if yes, the fact that the connected audio input device is an active audio input device is determined; if not, the passive audio input device is accessed.

The above are merely examples, and embodiments of the present invention are not limited thereto.

Based on the structure of the detection circuit, the embodiment of the present invention further provides an audio input detection method, which can be implemented by using the detection circuit shown in fig. 2. As shown in fig. 3, includes:

step 301, controlling the switch module to conduct a connection path between the bias voltage module and the audio input end, and acquiring a first audio signal through the audio encoding and decoding module.

And step 302, controlling the switch module to disconnect the connection path, and acquiring a second audio signal through the audio coding and decoding module.

Step 303, determining that the audio input device is an active audio input device or a passive audio input device according to the first audio signal and the second audio signal.

The following describes two embodiments of the method for detecting the type of the audio input device by the detection circuit.

In a first mode

When the equipment is started, the main control chip controls the switch module to be conducted, and the bias voltage module is loaded at the audio input end. When an audio coding and decoding module of the equipment collects a first audio signal, if the amplitude of the first audio signal is 10 and is larger than a preset threshold value 2, the amplitude indicates that a sound signal received by the audio coding and decoding module at the moment exceeds the range of possible noise inside the equipment, the collected first audio signal is determined to be sound in the environment, an audio input device is connected into the equipment through an audio input end, then a switch module is disconnected, and a bias voltage module is disconnected, and if an active audio input device is externally connected at the moment, a second audio signal received by the audio coding and decoding module is still larger than the preset threshold value; if the external connection is a passive audio input device, the second audio signal received by the audio coding and decoding module is smaller than the preset threshold value, so that the type of the external audio input device is determined according to the relation between the second audio signal and the preset threshold value.

In the above embodiment, the main control chip controls the switch module to be turned on first, so that the switch module is turned off only when the first audio signal detected by the main control chip exceeds the preset threshold; and if the first audio signal does not exceed the preset threshold, continuously detecting the first audio signal so as to determine whether the equipment is externally connected with an audio source input device.

Of course, a feasible implementation manner may also be that the main control chip controls the switch module to be turned off first, and then controls the switch module to be turned on; or the main control chip periodically controls the on and off of the switch module, thereby realizing the detection of the type of the external audio input device.

Mode two

And judging the type of the externally connected audio input device only through the first audio signal. For example, a pressure sensor or a detection chip may be disposed at the audio input end to determine whether an audio input device is connected through a change in pressure or a change in current, and if it is determined that the audio input device is input, and if the bias voltage module is turned on, and if the amplitude of the first audio signal is detected to be 20 and exceeds the attack threshold 15, it is determined that the active audio input device is connected.

The above are merely examples, and embodiments of the present invention are not limited thereto.

In the prior art, because the type of the external audio input device cannot be detected, one monitoring device can only be externally connected with one type of audio input device. If the internal audio input gain of the monitoring equipment is small and the passive audio input device is externally connected, the acquired volume is low; if the internal audio input gain of the monitoring device is large, a sound break condition occurs.

The embodiment of the invention also provides a method for adjusting the internal gain of the monitoring equipment, which is used for adjusting the internal gain of the monitoring equipment according to the type after the type of the external audio input device is determined so as to ensure the quality of the audio collected by the monitoring equipment.

Optionally, an audio signal processing module may be further disposed in the circuit, and fig. 4 illustrates a possible audio input detection circuit, where the audio signal processing module is disposed behind the main control chip and configured to process an audio signal according to a first gain mode according to an instruction of the main control chip when the main control chip determines that the audio input device is a passive audio input device; and when the main control chip determines that the audio input device is an active audio input device, processing the audio signal according to the instruction of the main control chip and a second gain mode. Wherein the amplification degree of the first gain mode is greater than that of the second gain mode. The setting position of the audio signal processing module can be set by a person skilled in the art at will, and fig. 4 is only an example, and the embodiment of the present invention is not limited thereto.

For example, the main control chip determines that the audio input end is connected with the active audio input device through the first audio signal and the second audio signal, and because the gain circuit is arranged in the active audio input device, the main control chip sets a smaller gain for the active audio input device, for example, the gain is 2 times, so that the phenomenon that the amplitude of the audio signal collected from the audio input device is too large to break the sound can be avoided.

For another example, the master control chip determines that the audio input end is connected to the passive audio input device through the first audio signal and the second audio signal, and because the passive audio input device is not internally provided with the gain circuit, the master control chip sets a larger gain, for example, a gain of 5 times, for the passive audio input device, so that the audio signal collected from the audio input device cannot have the phenomenon that the amplitude of the signal is too small and the volume is too low.

Therefore, after the type of the audio input device is determined, the corresponding gain can be automatically set according to the type of the audio input device, so that the quality of the collected audio can be ensured when the equipment is connected into various types of audio input devices, the use diversity is increased, and the user experience is improved.

The function of setting different amplification gains of the audio signal processing module may be implemented by an audio codec chip, or by setting an operational amplifier, and the like, which is not limited in this embodiment of the present invention.

Optionally, when the audio input device is determined to be an active audio input device, the switch module is controlled to be switched off by the main control chip, so that the bias voltage module does not supply power to the active audio input device, and the sound breaking phenomenon is avoided. When the audio input device is determined to be the passive audio input device, the switch module is controlled to be closed through the main control chip, so that the bias voltage module supplies power for the passive audio input device, and the normal volume effect is guaranteed.

Optionally, when the active audio input device is switched on, the voltage at the audio input end is too high, which may affect the inside of the device, especially the bias circuit, so that the protection circuit may be set to protect. The protection circuit is disposed on the connection path of the bias voltage module for supplying power to the audio input device, as shown in fig. 5.

Optionally, a coupling module may be further disposed on an audio channel between the audio input device and the audio encoding and decoding module, for filtering out a direct current signal in the audio signal. As shown in fig. 6.

Optionally, a signal conditioning module may be further disposed between the coupling module and the audio codec module, and configured to filter out-of-bandwidth noise in the audio signal, and amplify the filtered audio signal, as shown in fig. 7. For example, a band-pass filter may be provided in the module to filter out high and low frequency signals, and a gain amplifier may be provided to amplify the audio signal. Therefore, whether the threshold value is exceeded or not can be judged by the follow-up main control chip based on more accurate audio signals. And the gain amplification function can make up the defect that the gain amplification amplitude of part of the audio coding and decoding chips is limited.

Optionally, a signal conditioning module may be further disposed between the audio input end and the audio codec module, as shown in fig. 8.

The above is merely an example, and those skilled in the art can select the above modules as needed to form the audio input detection circuit, which is not listed here.

Fig. 9 shows a specific structure diagram of a possible audio input detection circuit according to an embodiment of the present invention. As shown in fig. 9, the device includes an audio input terminal, a bias voltage module, a switch module, a protection circuit, a coupling module, a signal conditioning module, a main control chip, and an audio codec chip.

The protection circuit may be provided with an anti-electrostatic surge device, such as a transient diode D2A in fig. 9, for preventing an external circuit from interfering with the audio input detection circuit, and may further be provided with a diode D1, where the reverse blocking characteristic of the diode may prevent the external audio input voltage from affecting the power supply for providing the bias voltage module when the external audio input voltage is too high. The embodiment of the present invention does not limit the structure of the specific protection circuit.

The coupling module circuit is in capacitive coupling or other coupling modes and is responsible for filtering out direct current signals in the audio signals. As shown in fig. 9, capacitive coupling is provided, and the characteristic that the capacitor blocks direct current and alternating current is utilized. The embodiment of the invention does not limit the structure of the specific coupling module circuit.

Fig. 9 shows a possible structure of the bandpass filter circuit and the gain amplifier circuit, which includes a capacitor C3, a resistor R4 connected in parallel with the capacitor C3, an operational amplifier U1, resistors R3, R5, R6, and R7. The band-pass filter circuit is composed of a low-frequency filter circuit and a high-frequency filter circuit, for example, in fig. 9, C3 is used for filtering low-frequency signals, U1 is used for filtering high-frequency signals, and the gain amplifier circuit is mainly composed of an operational amplifier. The audio signal after filtering and amplifying has dc voltage division, so C1 can be set after the band-pass filter circuit and the gain amplifier circuit to filter the dc signal. The embodiment of the invention does not limit the structure of the specific signal conditioning module circuit.

The audio coding and decoding chip is used for coding and decoding the audio signal, namely the function of the audio coding and decoding module is realized; and the control module is also used for setting a corresponding gain mode according to the instruction of the main control chip, namely realizing the function of the audio signal processing module. For example, after the main control chip detects the first audio signal and the second audio signal and determines that the external connection is the active audio input device, the audio coding and decoding chip performs corresponding gain processing on the audio signal input by the active audio input device according to the instruction of the main control chip and in a second gain mode.

In order to better explain the embodiment of the present invention, the following describes the flow of the above-mentioned audio input detection method in a specific implementation scenario. As shown in fig. 10, the following steps are included.

Step 1001, the device initializes. The equipment can be various equipment which needs to be externally connected with an audio input device, such as monitoring equipment, a television, a computer and the like.

When the user opens the device, the device initializes and starts the detection program.

Step 1002, the switch module is closed through the main control chip, a connection path between the bias voltage module and the audio input end is conducted, and the bias voltage provided by the bias voltage module is applied to the audio input end.

Therefore, if a user accesses the audio input device into the equipment, no matter the audio input device is connected into an active audio input device or a passive audio input device, the sound signal can be detected due to the existence of the bias voltage module.

Step 1003, the audio coding and decoding chip detects whether the first audio signal is larger than a preset threshold value, if so, the audio input device is accessed, and the step 1004 is entered; if not, the process returns to step 1002 to continue to wait for the audio input device to be accessed.

And 1004, disconnecting the switch module, disconnecting a connecting path between the bias voltage module and the audio input end, and not supplying power to the audio input end by the bias voltage module.

In step 1003, it is confirmed that an audio input device is connected, then the switch module is turned off, and the bias voltage module is turned off to further determine whether the connected audio input device is an active audio input device or a passive audio input device.

Step 1005, the audio codec chip detects whether the second audio signal is greater than a preset threshold, if so, the process goes to step 1006; if not, go to step 1008.

Step 1006, determining the input source to be an active audio input device.

Step 1007, the audio signal is processed according to the second gain mode.

At step 1008, the input source is determined to be a passive audio input device.

Step 1009, the audio signal is processed according to the first gain mode, and the amplification degree of the first gain mode is greater than that of the second gain mode.

According to the embodiment of the invention, the characteristic that the audio signals have difference when the bias voltage module is switched on and switched off when the passive audio input device normally works is utilized, and the on-off of the bias voltage module is controlled by setting the switch module, so that the type of the audio input device is automatically determined according to the difference of the audio signals obtained under the two conditions of on-off, manual participation is not needed, and the user experience is improved. In addition, an audio processing and detecting chip is not required to be additionally arranged, and the method is simple and easy to implement and low in cost.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.