TWI822030B - Noise shaping digital automatic gain control system - Google Patents

Abstract

The present invention provides a noise-integrated digital automatic gain control system, comprising an audio receiving device, an analog-to-digital converter, a digital audio gain self-adaptive generating device, and a gain adjusting device. The analog-to-digital converter is used for converting the analog audio of the audio receiving device into digital audio. The digital audio gain adaptive generating device generates a virtual heave wave signal according to a feedback audio, and generates an output code according to the virtual heave wave signal and further converts it into a gain ratio, so that the discontinuous noise of the gain ratio is pushed to high frequencies , so that the resolution of the low frequency part is greatly improved, and the gain of the digital audio is controlled according to the gain ratio, converted into a playback audio, and then sent to the audio output device.

Description

Noise integer digital automatic gain control system

The invention relates to a digital automatic gain control system, and in particular to a noise integer type digital automatic gain control system.

Automatic Gain Control (Automatic Gain Control) is widely used in various industries, especially in actual audio conferencing systems. Due to gender or speaker's habits, there will be a huge difference in the volume amplitude of the audio system output end, such as when When the speaker is farther away from the microphone, a lower volume will be output; when the speaker is closer to the microphone, a higher volume will be output. Because such a situation will cause all participants in the same conference to suddenly loudly/quietly sound, causing trouble to the participants.

In this way, the use of automatic gain control can automatically provide gain compensation. When the speaker's voice is too loud, the gain will be automatically reduced to maintain the sound in the meeting at a certain volume; conversely, when the speaker's voice is too low, the gain will be automatically reduced. Automatically increase the gain to maintain the sound in the meeting at a certain volume, so that participants can conduct the meeting smoothly.

However, automatic gain control adjustment can cause discomfort to participants in the conference because of the uneven adjustment rate.

The main purpose of the present invention is to provide a noise integer digital automatic gain control system, which includes an audio receiving device, an analog-to-digital converter, a digital audio gain adaptive generation device, and a gain adjustment device. The audio receiving device is used for receiving sound and converting it into analog audio. The analog-to-digital converter is connected to the audio receiving device, and the analog-to-digital converter is used to receive the analog audio and convert it into digital audio. The digital audio gain adaptive generation device is connected to the analog-to-digital converter to receive the digital audio. The digital audio gain adaptive generation device includes a virtual up and down wave generation module, a noise shaping module connected to the virtual up and down wave generation module, a mapping module connected to the noise shaping module, and a Connected to the gain adjustment module of the mapping module, the virtual up and down wave generation module receives feedback audio from an audio feedback device and outputs a virtual up and down wave signal based on whether the feedback audio exceeds the preset volume range. The noise The shaping module generates an output code based on the virtual up and down wave signal of the virtual up and down wave generation module, and the mapping module obtains an updated gain factor based on the output code mapping, wherein the input and output of the noise shaping module The system conforms to the following formula: ; ; Among them, x[n] is the value of the virtual up and down wave signal at nth level, y[n] is the output code at nth level, w[n] is the transition between x[n] and y[n] Function, Nbits_Quantizer() is the function of multi-level quantizer. The gain adjustment device is connected to the analog-to-digital converter and the digital audio gain adaptive generation device, controls the gain of the digital audio according to the gain factor, converts the digital audio into a playback audio according to the gain and then sends it to an audio output device.

To sum up, compared with the conventional technology, the present invention can push discontinuous noise to high frequency through noise shaping, so that the resolution of the low frequency part is improved, and the adjustment process can be smoother and faster than the previous technology. Avoid discomfort caused by volume adjustment rate.

The detailed description and technical content of the present invention are described below with reference to the drawings. Furthermore, for the convenience of explanation, the proportions of the drawings in the present invention may not be drawn according to actual proportions. These drawings and their proportions are not intended to limit the scope of the present invention, and are explained here.

The "device", "device", "module" and the corresponding functions described in the present invention can be executed by a single chip or a combination of multiple chips. The number of these chip configurations is not limited to the present invention. The scope to be limited. In addition, the chip can be, but is not limited to, a processor (Processor), a Central Processing Unit (CPU), a microprocessor (Microprocessor), a Digital Signal Processor (DSP), a special application Combinations of integrated circuits (Application Specific Integrated Circuits, ASIC), programmable logic devices (Programmable Logic Device, PLD) and other devices are not limited in the present invention. The aforementioned chips can have separate or shared memory units, and the memory units are used to assist in data storage. In a feasible embodiment, the memory unit may be (but is not limited to) cache memory (Cache memory), dynamic random access memory (DRAM), persistent memory (Persistent Memory), etc. Devices or combinations thereof used for storing and retrieving data are not limited in the present invention.

The following is a description of one embodiment of the present invention. Please refer to "Figure 1", "Figure 2" and "Figure 3" together, which are block diagrams of a noise integer type digital automatic gain control system and digital audio gain adaptation. Generate a block diagram of the device and a block diagram of the noise shaping module, as shown in the figure.

Please refer to "Figure 1" first. This embodiment shows a noise integer digital automatic gain control system 100, which mainly includes an audio receiving device 10, an analog-to-digital converter 20, a feedback audio device 30, and a digital audio gain adaptive generation device. 40. Gain adjustment device 50, and audio output device 60.

The audio receiving device 10 is mainly used to receive sound signals in the environment (such as the user's voice). In one embodiment, the audio receiving device 10 may be, for example but not limited to, a microphone, a pickup, or other devices that can be used to receive environmental sound waves, which are not limited in the present invention.

The analog-to-digital converter 20 (Digital to analog converter, DAC) is used to convert the audio signal of the audio receiving device 10 from an analog signal into a digital signal, and output a digital audio to the digital audio gain adaptive generation device 40 .

The feedback audio device 30 is used to feed back the audio received by the sound detection device 70 to the digital audio gain adaptive generation device 40, thereby forming a closed loop system. In one embodiment, the feedback audio device 30 can be, for example, a feedback controller (Feedback Controller) or any feedback circuit, which is not limited in the present invention. In one embodiment, the feedback audio device 30 can capture the output of the audio output device 60 through a sound detection device 70 (such as a microphone) disposed near the audio output device 60 to obtain the feedback audio, and Feedback to the virtual up-and-down wave module (will be described later) of the digital audio gain adaptive generation device 40; in another embodiment, the feedback audio device 30 obtains the playback through the output of the gain adjustment device 50 The played audio is fed back to the virtual up and down wave module of the digital audio gain adaptive generation device 40 as the feedback audio.

The digital audio gain adaptive generation device 40 is connected to the analog-to-digital converter 20 and the feedback audio device 30 to receive the digital audio and feedback audio. Please refer to "Figure 2". The digital audio gain adaptive generation device 40 mainly includes a virtual up and down wave generation module 42, a noise shaping module 44 provided at the output of the virtual up and down wave generation module 42, and a noise shaping module 44 provided at the output of the virtual up and down wave generation module 42. The noise shaping module 44 outputs a mapping module 46 .

The input of the virtual up-and-down wave generation module 42 is connected to the output of the feedback audio device 30. The virtual up-and-down wave generation module 42 receives feedback information from the feedback audio device 30 and determines whether the feedback information exceeds a predetermined value. Set the volume range to output virtual up and down wave signals. Specifically, the virtual up-and-down wave generation module 42 can store a preset volume range through a storage device (not shown). The preset volume range can be set at the factory, or set by the user according to the actual situation. There is no limitation in the present invention. The virtual up-and-down wave generating module 42 outputs a virtual down-wave signal when receiving the feedback audio is higher than the upper limit of the preset volume range; the virtual up-and-down wave generating module 42 receives the feedback audio is lower than the upper limit of the preset volume range. A virtual rising wave signal is output at the lower limit of the preset volume range.

The noise shaping module 44 generates an output code according to the virtual up and down wave signal (virtual up wave or virtual down wave) of the virtual up and down wave generation module 42 . Please refer to "Figure 3". In one embodiment, the noise shaping module 44 includes a first adder A1, a second adder A2, a first delayer D1, a second delayer D2, a third delayer D3, The first multiplier M1, the second multiplier M2, and the multi-level quantizer NQ. The input terminal of the first adder A1 is connected to the output of the virtual up and down wave generation module 42, the output of the first multiplier M1, the output of the second multiplier M2, and the output of the third delayer D3; the second adder The input terminal of the second adder A2 is connected to the output of the first adder A1 and the output of the multi-level quantizer NQ, wherein there is further included between the input terminal of the second adder A2 and the output of the first adder A1 An inverter (not shown) is used to form a subtraction loop; the input terminal of the first delayer D1 is connected to the output of the second adder A2, and the input terminal of the first multiplier M1 is connected to the output terminal of the first delayer D1. output to form a first-order delay feedback loop; the input end of the second delayer D2 is connected to the output of the first delayer D1, and the input of the second multiplier M2 is connected to the output of the second delayer D2 to form A second-order delay loop, in which the output of the second multiplier M2 and the first adder A1 further include an inverter (not shown) to form a subtraction loop; the input end of the third delay D3 is connected to the second The output of the delayer D2 forms a third-order delay loop; the input end of the multi-level quantizer NQ is connected to the output of the first adder A1, thereby converting the output of the first adder A1 (for example, w[n]) into Quantify the code.

The first adder A1 and the second adder A2 may include, but are not limited to, an adder, a half adder, a full adder, a ripple carry adder, and a carry-ahead. Adder implementation, or other digital circuits, logic gates, or combinations thereof for performing addition operations are not limited in the present invention.

The first delayer D1, the second delayer D2, and the third delayer D3 may include but are not limited to integrators, counters, and other circuits that can be used for signal delay or integration, or a combination thereof. , is not limited in the present invention.

The first multiplier M1 and the second multiplier M2 may include but are not limited to operational amplifiers (op amps), or circuits composed of a plurality of adders, or other similar devices, which are not included in the present invention. limit.

Please refer to "Figure 2" again. The input of the mapping module 46 is connected to the output of the noise shaping module 44. The mapping module 46 can be a processor with an associative array lookup function (lookup table) or Arithmetic Logic Unit (ALU) is not limited in the present invention. The mapping module 46 obtains the updated gain factor according to the output code mapping, and transmits the gain factor to the gain adjustment device 50 .

The gain adjustment device 50 is connected to the analog-to-digital converter 20 and the digital audio gain adaptive generation device 40, controls the gain of the digital audio according to the gain factor, and converts the gained digital audio into a playback audio for transmission. to the audio output device 60; the sound output by the audio output device 60 or the received playback audio is fed back to the digital audio gain adaptive generation device 40 through the feedback audio device 30, thereby realizing closed-loop control. In another embodiment, the gain adjustment device 50 can transmit playback audio to a memory unit or communication module. This part depends on the subject matter of the implementation and is not within the scope of the present invention.

The above describes a specific embodiment of the hardware architecture of the present invention, and the working procedure of the present invention will be further described below. Please refer to "Figure 4", which is a schematic diagram of the work flow of the noise integer digital automatic gain control system of the present invention, as shown in the figure.

First, the noise integer digital automatic gain control system 100 of the present invention is started (step S201).

At this time, the audio receiving device 10 receives the sound and converts the sound into analog audio (step S202); the converted analog audio is sent to the analog-to-digital converter 20, and the analog-to-digital converter 20 converts the analog audio into digital message (step S203).

The virtual up and down wave generation module 42 in the digital audio gain adaptive generation device 40 receives the feedback audio from the feedback audio device and outputs a virtual up and down wave signal according to whether the feedback audio exceeds the preset volume range (step S204). When the noise shaping digital automatic gain control system 100 of the present invention is started, since there is no feedback audio from the previous stage, the gain adjustment device 50 can directly output the original audio signal received by the audio receiving device 10 without going through Adjustment of subsequent steps S205-S208. The feedback information obtained in the following step S208 will be used to modify the next level playback information.

In this embodiment, the digital audio gain adaptive generation device 40 outputs a virtual down wave signal when it receives that the feedback audio is higher than the upper limit of the preset volume range; the virtual up and down wave generation module receives the feedback When the audio is lower than the lower limit of the preset volume range, a virtual rising wave signal is output. In one embodiment, the falling wave signal may be a falling range from 1 (maximum) to 0 (minimum); in one embodiment, the rising wave signal may be a rising range from 0 (minimum) to 1 (maximum). interval. In other embodiments, the peak value and waveform (such as triangle wave, sine wave, etc.) of the rising segment signal and the falling segment signal can be adjusted according to the actual content and are not limited in the present invention.

The noise shaping module 44 generates output codes according to the virtual up and down wave signals of the virtual up and down wave generation module (step S205). Specifically, when the noise shaping module 44 receives the virtual up and down wave signal, it obtains the output code according to the following formula. The input and output of the noise shaping module conform to the following formula: ; ; Among them, x[n] is the value of the virtual up and down wave signal at nth level, y[n] is the output code at nth level, w[n] is the transition between x[n] and y[n] Function, bits_Quantizer() is the function of multi-level quantizer.

According to the above formula, the The function is as follows: ; Among them, M is the preset level value of the multi-level quantizer, and floor() is a floor function.

The mapping module 46 obtains the updated gain factor according to the output code mapping (step S206). In one embodiment, the input and output of the mapping module 46 conform to the following formula: ; ; in, for the first the output code input to the mapping module 46, for the first The gain factor of the stage mapping output, Z is a positive integer, Add value (in dB) to the preset volume gain step.

Next, the gain adjustment device 50 controls the gain of the digital audio according to the gain factor, and converts the digital audio into a playback audio according to the gain (step S207). In one embodiment, the input and output of the gain adjustment device comply with the following formula: ; in, For this mapping module The gain magnification input to the gain adjustment device 50 in stages, for the first The digital audio input to the volume adjustment module 38 in stages, For the volume adjustment module 38 on page 38 The playback audio output by the stage. The playback audio will be input to the audio output device 60 (or memory unit, communication module, etc.). The application field of the modified audio signal output by the present invention is not within the scope of the present invention, and will be described here.

In the above steps, the first-level adjustment of the playback audio has been completed. At this time, the feedback audio device further feeds back the obtained feedback audio to the virtual up and down wave generation module (step S208), and repeats steps S202~ Step S208: Perform next-level adjustment and obtain next-level feedback information to form a closed loop until the noise integer digital automatic gain control system is turned off.

To sum up, compared with the conventional technology, the present invention can push discontinuous noise to high frequency through noise shaping, so that the resolution of the low frequency part is improved, and the adjustment process can be smoother and faster than the previous technology. Avoid discomfort caused by volume adjustment rate.

The present invention has been described in detail above. However, what is described above is only one of the preferred embodiments of the present invention. It should not be used to limit the scope of the present invention. That is, anything based on the patent scope of the present invention is made. Equal changes and modifications should still fall within the scope of the patent of the present invention.

100: Noise integer digital automatic gain control system 10: Audio receiving device 20: Analog-to-digital converter 30: Feedback audio device 40: Digital audio gain adaptive generation device 42:Virtual rising and falling wave generation module 44:Noise shaping module A1: First adder A2: Second adder D1: first delayer D2: Second delayer D3: The third delayer M1: first multiplier M2: Second multiplier NQ: multi-level quantizer 46: Mapping module 50: Gain adjustment device 60: Audio output device 70: Sound detection device Step S201~Step S208

Figure 1 is a block diagram of the noise integer digital automatic gain control system of the present invention.

FIG. 2 is a block diagram of the digital audio gain adaptive generation device of the present invention.

FIG. 3 is a block diagram of the noise shaping module in the present invention.

Figure 4 is a schematic diagram of the work flow of the noise integer digital automatic gain control system of the present invention.

100: Noise integer digital automatic gain control system

10: Audio receiving device

20: Analog-to-digital converter

30: Feedback audio device

40: Digital audio gain adaptive generation device

50: Gain adjustment device

60: Audio output device

70: Sound detection device

Claims (5)

A noise integer digital automatic gain control system includes: an audio receiving device for receiving sound and converting it into analog audio; an analog-to-digital converter connected to the audio receiving device, and the analog-to-digital converter is used for To receive the analog audio and convert it into digital audio; a digital audio gain adaptive generation device is connected to the analog-to-digital converter to receive the digital audio, including a virtual rise and fall wave generation module, a device connected to the A noise shaping module of a virtual rise and fall wave generation module, and a mapping module connected to the noise shaping module; the virtual rise and fall wave generation module receives feedback information from a feedback audio device and based on the feedback Whether the audio exceeds the preset volume range and outputs a virtual up-and-down wave signal, wherein the virtual up-and-down wave generating module outputs a virtual down-wave signal when it receives the feedback audio is higher than the upper limit of the preset volume range, and the virtual up-and-down wave generation module When the module receives that the feedback audio is lower than the lower limit of the preset volume range, it outputs a virtual rising wave signal; the noise shaping module generates an output code based on the virtual rising and falling wave signal of the virtual rising and falling wave generation module, Among them, the input and output of the noise shaping module conform to the following formula: y[n]=Nbits_Quantizer(w[n]); w[n]=x[n]+(y[n-3]-w[ n-3])-3×(y[n-2]-w[n-2])+3×(y[n-1]-w[n-1]); where x[n] is The value of the virtual up and down wave signal at nth level, y[n] is the output code at nth level, w[n] is the transfer function between x[n] and y[n], Nbits_Quantizer() is multi-level quantization function of the converter; the mapping module obtains the updated gain factor based on the output code mapping, where the input and output of the mapping module conform to the following formula: if Y[N]

2 ^{( Z -1)} , D[N]=[-(2 ^{( Z -1)} -Y[N])]×α; if Y[N]>2 ^{( Z -1)} , D[N]=[ 2 ^{( Z -1)} + (Y[N]-2 ^Z )]×α; where, Y[N] is the output code input to the mapping module in the Nth stage, and D[N] is the Nth stage mapping. For the output gain magnification, Z is a positive integer, α is a preset volume gain step increment value; and a gain adjustment device is connected to the analog-to-digital converter and the digital audio gain adaptive generation device, according to the gain magnification Control the gain of the digital audio, and convert the digital audio into playback audio according to the gain. The noise integer automatic gain control system as described in claim 1 further includes an audio output device for playing the playback audio, and the feedback audio device is through a sound detection device located near the audio output device. The device captures the output of the audio output device to obtain the feedback information and feeds it back to the virtual up and down wave generation module. The noise integer type digital automatic gain control system as described in claim 1, wherein In the method, the feedback audio device obtains the playback audio through the output of the gain adjustment device and feeds the playback audio back to the virtual up and down wave generation module as the feedback audio. The noise integer digital automatic gain control system as described in request 1, wherein the function of Nbits_Quantizer() is as follows:

Among them, M is the preset level value of the multi-level quantizer, and floor() is a floor function. The noise integer type digital automatic gain control system as described in claim 1, wherein the input and output of the gain adjustment device comply with the following formula:

Among them, D[N] is the gain magnification input to the volume adjustment module at the Nth stage, M[N] is the digital audio input to the volume adjustment module at the Nth stage, and V[N] is the Nth stage. Outputs the adjusted playback audio.

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