CN100593323C - Automatic sound volume adjusting method and system - Google Patents

Abstract

A method for automatically regulating volume includes dividing input audio data to be two bands of low and high and calculating average volume of the two separately, converting average volume to be onlog domain and obtaining control gain data according to control curve value, converting obtained data to be on linear domain, multiplying said data separately by delayed corresponding band data and adding as well as outputting high/ low band audio data after multiplication.

Description

The method and system that a kind of automatic volume is regulated

Technical field

The present invention relates to the method and system that a kind of automatic volume is regulated, relate in particular to a kind of volume of can carrying out automatically and regulate, prevent the method and system that volume changes suddenly.

Background technology

The user can be set to certain numerical value by the parameters such as volume that TV programme manually is set, but the different program source volumes of TV are either large or small, such as, the audio volume gap of different channel signal source is very big; Simultaneously, the advertisement of intercutting is for the purpose that causes that spectators note, often greater than the volume of normal program.Therefore, when the program of television channel change or a certain channel changed, the unexpected rising or the reduction that often bring volume brought spectators uncomfortable impression.

The patent No. is that 200320119709 utility model has proposed following technical scheme from the angle that analog signal is handled and solves the problems referred to above: detect the audio volume signal of audio input end and send into control circuit by testing circuit, in when, audio signal blasting or skew taking place should need volume when, control circuit connection volume control circuit; Use " adding " or " subtracting " key to regulate the purpose that the sound accompaniment voltage amplitude is realized automatic volume control by volume control circuit.

Top technical scheme has realized the automatic adjusting of volume to a certain extent, but only undertaken by the technical scheme that the simulated audio signal amplitude is revised, regulate the sound accompaniment voltage amplitude by " adding " or " subtracting " key, might introduce extra noise because of the too fast variation of control signal.

Simultaneously, the method volume controlled automatically from the digital processing angle has also appearred in the market, by A/D converter analog signal is handled, and utilize the root mean square of the voice data after the buffer computing, obtain the average volume of input data, after log-domain provides the control law of importing the data average volume, export through D/A converter.Because technique scheme is unified to handle to the audio frequency of input, when the low-frequency component of input signal is occupied an leading position, handle through said method, can lose by the radio-frequency component that the script amplitude is very little, make that the audio frequency after handling has lost original tone color or content; Use buffer to calculate root mean square and occupy a large amount of system resources.

In order to overcome the problems referred to above, need a kind of method and system that can carry out the volume adjusting automatically, the unexpected variation of output volume can be controlled within limits, and can not cause audio distortions.This method and system not only can be applied to television system, more can be generalized to the field that portable terminal, broadcast system, computer, vehicle-mounted CD etc. use audio signal.

Summary of the invention

The objective of the invention is at existing audio signal processing technique in the volume defective aspect the adjusting automatically, a kind of self-regulating method of volume that realizes is provided, high frequency, low frequency and the targetedly respectively processing of this method by distinguishing voice data can not lost outputting audio data high-frequency signal part; By introducing smoothing filter and design control curve, make the variation of control signal smooth-out.

The present invention also aims to provide a kind of volume self-regulating system, can be widely used in the systems such as TV, portable terminal, computer, vehicle-mounted CD, realize automatic adjusting, can the effect of audio frequency not impacted volume.

For achieving the above object, the invention provides the method that a kind of automatic volume is regulated, comprise the steps:

Step 1, input audio data is divided into high band voice data and low-frequency range voice data;

Step 2, calculate the average volume parameter of high and low frequency section audio data respectively;

Step 3, with the average volume data transaction to log-domain, taking parameter on trendline according to control obtains the ride gain data;

Step 4, with the data transaction that obtains to linear domain, multiply each other respectively with through the corresponding frequency band data that postpone;

Step 5, the high and low frequency section audio data addition output that obtains after will multiplying each other.

The present invention also provides a kind of automatic volume regulating system, receives the audio signal of A/D converter output, carries out sending after automatic volume is regulated; Comprise the low pass filter, root mean square calculation module, control module and the multiplication module that connect successively, low pass filter blocks is connected to multiplier module by Postponement module; Also comprise the high pass filter, root mean square calculation module, control module and the multiplication module that connect successively, high pass filter block is connected to multiplier module by Postponement module; Described two multiplier modules are connected respectively to adder Module.

Therefore, the present invention has the following advantages:

1, automatic volume is regulated with the volume control of output audio within limits, prevents that volume from increasing suddenly or reduce, and makes the audience obtain comfortable auditory perception;

2, adopt high pass/low pass filter that input audio signal is divided into two frequency ranges and carry out the specific aim processing, preserved and handled preceding original tone color and content;

3, root mean square calculation adopts the single order wireless pulses filter of certain hour constant to calculate, and has avoided adopting and has utilized buffer to carry out calculating in the computational methods the excessive problem of resource requirement usually;

4, the control curve adopts interactive knee adapt (soft knee) control curve, uses smoothing filter to carry out smoothing processing simultaneously, has avoided owing to extra noise is introduced in the too fast variation of control signal.

Below in conjunction with drawings and Examples, technical scheme of the present invention is described in further detail.

Description of drawings

Fig. 1 is the flow chart of prior art sound intermediate frequency processing method;

Fig. 2 is the flow chart of automatic volume control method of the present invention;

Fig. 3 is for carrying out the method schematic diagram of root mean square calculation in the automatic volume processing of the present invention;

Fig. 4 is soft knee control curve synoptic diagram in the automatic volume processing of the present invention;

Fig. 5 is for carrying out the system block diagram of Audio Processing in the prior art;

Fig. 6 carries out the system block diagram that automatic volume is regulated for the present invention.

Embodiment

Common Audio Processing is converted to digital audio-frequency data with input audio data, and controls according to the parameter that the user is provided with, and is converted to analog audio data output again; Simultaneously, in order to overcome the unexpected variation of volume, before the control audio data being set, add the method that automatic volume is regulated according to the user.Referring to Fig. 1, be the flow chart of prior art sound intermediate frequency processing method.

The invention provides a kind of defective of regulating, carry out the method that automatic volume is regulated,, comprise the steps: referring to Fig. 2 at existing automatic volume

Step 101, use high pass/low pass filter are divided into high band voice data and low-frequency range voice data with input audio data; Because the frequency range of supper bass is selected 0-200Hz usually, therefore the cut-off frequency (cutoff frequency) of distinguishing two frequency ranges of height is 200Hz, the following voice data of 200Hz is the low-frequency range voice data, and the above voice data of 200Hz is the high band voice data;

Step 102, use single order infinite impulse response filter to calculate the root mean square (Root Mean Square is called for short RMS) of low-and high-frequency segment data respectively, obtain height frequency range average volume parameter separately with certain hour constant;

Step 103, with the average volume data transaction that obtains to log-domain;

Step 104, control takes parameter on trendline according to predefined soft knee, obtains the ride gain data;

Step 105, will be transformed into linear domain according to the log-domain voice data that the control curve obtains;

Step 106, use single order infinite impulse response filter carry out the low pass smothing filtering;

The low-and high-frequency section audio data of step 107, process Filtering Processing multiply each other through the corresponding data that postpones with this frequency range respectively;

Step 108, the low-and high-frequency section audio data addition that obtains after multiplying each other;

Step 109, output.

In the superincumbent step 102, the schematic diagram that carries out the RMS computing is referring to Fig. 3.Transfer function is:

$H\left(z\right)=\frac{\mathrm{TAV}}{1-(1-\mathrm{TAV})Z^{-1}}$

Wherein, TAV is a mean coefficient, and its value asks the relation of the used window length RMS_average_in_Samples of mean time as follows with adopting sliding window:

TAV＝exp(ln(0.01)/RMS_average_in_Samples)；

The RMS computing formula is as follows:

$\mathrm{RMS}=\sqrt{\frac{x_1^2+x_2^2+\·\·\·+x_N^2}{N}},$ X wherein ₁, x ₂..., x _NBe respectively the volume of the voice data of input.

In the superincumbent step 104, control takes parameter on trendline according to soft knee, and referring to Fig. 4, soft knee control curve is according to the design of Hard knee control curve on the log-domain.In hard knee curve, when the dB value of input during less than-30dB, output with import identically, promptly ride gain is 0dB; And when the dB value of input during greater than-30dB, output valve all remains-30dB, though the i.e. variation imported of ride gain changes; Soft knee curve is according to designing by the thought of smooth transition in hard knee corner.In input value be-30dB near the time, output valve is carried out value according to smooth curve among the figure, Here it is, and control takes parameter on trendline according to predefined soft knee.

In step 105, the algorithm of smothing filtering is identical with the algorithm of asking for RMS, but the mean coefficient TAV in its transfer function is not invariable, in rising trend and be in the downward trend both of these case at ride gain, the value of TAV is different, and (16s) was little when the time constant during ascendant trend (20ms) ratio descended.

Referring to Fig. 5, be the system schematic of carrying out Audio Processing in the prior art, comprise the A/D modular converter, audio processing modules and the D/A modular converter that connect successively; Wherein, audio processing modules is set according to the user voice data is carried out control and treatment.Simultaneously, in order to overcome the unexpected variation of volume, before audio processing modules, add the automatic volume adjustment module.

Referring to Fig. 6, be the system block diagram of the automatic volume regulating system among the present invention, this automatic volume adjustment module is regulated the size of input audio data RMS automatically, with the control of the volume of output audio within limits, prevents the unexpected increase of volume.

The automatic volume regulating system comprises low pass filter 1, root mean square calculation module 31, log-domain modular converter 41, dynamic control law and threshold module 51, linear domain modular converter 61, smoothing filter module 71 and the multiplication module 81 that connects successively, and low pass filter 1 is connected to multiplier module 81 by Postponement module 91; Also comprise the high pass filter 2, root mean square calculation module 32, log-domain modular converter 42, dynamic control law and threshold module 52, linear domain modular converter 62, smoothing filter module 72 and the multiplication module 82 that connect successively, high pass filter 2 is connected to multiplier module 82 by Postponement module 92; Two multiplier modules 81 and 82 are connected respectively to adder Module 10.

In this system, what low pass filter 1 and high pass filter 2 adopted is second order wireless pulses response filter; Root mean square calculation module 31 and 32 all is the single order infinite impulse response filter with certain hour constant; Dynamically design soft knee control curve in control law and threshold module 51 and 52 in advance, the log-domain voice data that receives is taken parameter on trendline according to interactive knee adapt control, obtain ride gain; Smoothing filter module 71 and 72 adopts for the signal increase and the situation that reduces has the single order wireless pulses respective filter of different time constant.

It should be noted last that, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement technical scheme of the present invention, and not break away from the spirit and scope of technical solution of the present invention.

Claims (11)

1, a kind of method of automatic volume adjusting is characterized in that, comprises the steps:

Step 1, input audio data is divided into high band voice data and low-frequency range voice data;

Step 2, calculate the average volume parameter of high and low frequency section audio data respectively;

Step 3, with the average volume data transaction to log-domain, taking parameter on trendline according to control obtains the ride gain data;

Step 4, with the data transaction that obtains to linear domain, multiply each other respectively with through the corresponding frequency band data that postpone;

Step 5, the high and low frequency section audio data addition output that obtains after will multiplying each other.

2, the method for automatic volume adjusting according to claim 1, it is characterized in that, in the described step 1, the step that input audio data is divided into high band voice data and low-frequency range voice data is: use high pass/low pass filter that input audio data is divided into high band voice data and low-frequency range voice data.

3, the method for automatic volume adjusting according to claim 1, it is characterized in that, in the described step 2, the average volume parameter of calculating high and low frequency section audio data respectively comprises: use the single order infinite impulse response filter of certain hour constant to carry out root mean square calculation, obtain the average volume parameter of high and low frequency section audio data.

4, the method for automatic volume adjusting according to claim 1 is characterized in that, the control curve is an interactive knee adapt control curve in the step 3.

5, the method for automatic volume adjusting according to claim 1 is characterized in that, is transformed in the step 4 after the linear domain, carries out smoothing processing one time, multiplies each other again with through the corresponding frequency band data that postpone.

6, the method for automatic volume adjusting according to claim 5 is characterized in that, the method that described smoothing processing adopts is the low pass smothing filtering.

7, a kind of automatic volume regulating system receives the audio signal that A/D converter is exported, and carries out sending after automatic volume is regulated; It is characterized in that comprising the low pass filter, root mean square calculation module, control module and the multiplication module that connect successively, low pass filter blocks is connected to multiplier module by Postponement module; Also comprise the high pass filter, root mean square calculation module, control module and the multiplication module that connect successively, high pass filter block is connected to multiplier module by Postponement module; Described two multiplier modules are connected respectively to adder Module.

8, automatic volume regulating system according to claim 7 is characterized in that, described root mean square calculation module is the single order infinite impulse response filter with certain hour constant.

9, automatic volume regulating system according to claim 7 is characterized in that, described control module comprises the log-domain modular converter that connects successively, dynamic control law and threshold module and linear domain modular converter; Dynamically design interactive knee adapt control curve in control law and the threshold module makes the log-domain voice data that receives take parameter on trendline according to interactive knee adapt control, obtains ride gain.

10, automatic volume regulating system according to claim 7 is characterized in that, between described control module and the multiplier module, also has the smoothing filter module, on linear domain voice data is carried out smoothing processing.

11, automatic volume regulating system according to claim 10 is characterized in that, described smoothing filter module is to have the single order wireless pulses respective filter of different time constant for the signal increase and the situation that reduces.

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