CN102122927B - Volume control circuit and method thereof - Google Patents

Abstract

The present invention relates to a volume control circuit and its method. The volume control circuit comprises a signal strength calculation circuit, a low-pass filter, an averager, a gain calculation circuit, a buffer circuit and a volume adjustment circuit. The signal strength computing circuit generates a first signal strength value corresponding to the signal strength of the channel data. The low-pass filter performs a low-pass filtering operation on the first signal strength value to generate a second signal strength value. The averager performs an average operation on the second signal strength value and the previous M-1 second signal strength values to obtain a third signal strength value, where M is a natural number greater than 1. The gain calculation circuit refers to the adjustment condition and obtains the original gain value according to the third signal strength value. The buffer temporarily stores channel data. The volume adjustment circuit generates an adjustment gain value according to the original gain value to adjust the channel data stored in the buffer.

Description

Volume control circuit and method thereof

technical field

The present invention relates to a volume control circuit and its method, and in particular to an automatic volume control (Automatic Volume Control, AVC) volume control circuit and its method.

Background technique

In today's era of rapid technological development, volume control circuits with automatic volume control have been widely used in various electronic products. For example, the volume control circuit is applied in digital television. When the intensity of the sound played by digital TV changes drastically, for example, when the channel is turned or an advertisement is entered, the volume control circuit automatically generates an adjustment gain value to adjust the volume of the sound, so that the intensity of the sound can be maintained within a specific range, allowing users to use When the audience turns the channel or watches an advertisement, they will not feel a large volume change, but can avoid hearing discomfort.

Generally speaking, in order to accurately judge the change trend of the intensity of the sound signal, the traditional volume controller needs to refer to a large number of sound signals to calculate the adjustment gain value. In this way, the delay time td for the traditional volume control circuit to control the sound signal will be longer, as shown in Figure 1, which shows the operation schematic diagram of the traditional volume control circuit, and the signal S represents the sound signal controlled by the traditional volume control circuit . When the strength of the signal S is excessively increased at the time point T1, the traditional volume control circuit responds at the time point T2 to adjust the gain value to suppress the strength of the signal S. The period defined by the time points T1 and T2 is the delay time td.

In order to solve the problem that the delay time td is too long, the traditional volume control circuit needs to set a long buffer (Buffer) to store the sound data at these time points. In this way, the cost of the traditional volume control circuit will be too high, thereby reducing product competitiveness.

Contents of the invention

The purpose of the present invention is to provide a volume control circuit and its method, which can reduce the required buffer size, low cost and short delay time for automatic volume adjustment.

According to the present invention, a volume control circuit is provided for generating adjustment gain values to adjust multiple pieces of channel data of multiple channels. The volume control circuit includes a signal strength calculation circuit, a low-pass filter, an averager, a gain calculation circuit, a buffer circuit and a volume adjustment circuit. The signal strength computing circuit is used for receiving and generating a first signal strength value corresponding to the signal strength of the channel data. The low-pass filter is used for low-pass filtering the first signal strength value to generate the second signal strength value. The averager is used to receive the second signal strength value, and perform an average operation on the second signal strength value and the first M-1 second signal strength values of the previous M-1 time points to obtain a third signal strength value, and M is A natural number greater than 1. The gain computing circuit is used for obtaining the original gain value according to the third signal strength value with reference to at least one adjustment condition. The buffer is used to temporarily store channel data. The volume adjustment circuit is used for generating an adjustment gain value according to the original gain value, and adjusting the channel data stored in the buffer according to the adjustment gain value.

According to the present invention, a volume control method is provided, which is used for generating adjustment gain values to adjust multiple pieces of channel data of multiple channels. The volume control method includes the following steps: firstly generate a first signal strength value corresponding to the signal strength of the channel data; then perform a low-pass filter operation on the first signal strength value to generate a second signal strength value; then The signal strength value is averaged with the first M-1 second signal strength values of the first M-1 time points to obtain the third signal strength value, M is a natural number greater than 1; then, referring to the adjustment condition, according to the third signal strength value The intensity value is used to obtain the original gain value; then the buffer is used to temporarily store the channel data; and then the adjusted gain value is generated according to the original gain value, and the channel data stored in the buffer is adjusted according to the adjusted gain value.

Description of drawings

In order to make the above content of the present invention more obvious and understandable, preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram illustrating the operation of a conventional volume control circuit.

FIG. 2 is a block diagram of a volume control circuit.

FIG. 3 is a block diagram of a volume control circuit according to an embodiment of the invention.

FIG. 4 is a diagram showing a gain relationship diagram of the gain operation circuit.

FIG. 5 is a graph showing the input-output relationship of the hysteretic operational amplifier.

FIG. 6A and FIG. 6B are waveform diagrams of the sound signal corresponding to the channel data DA1 and the signal strength value VA1 respectively.

FIG. 7 shows waveforms of signal strength values VA2 ′ and VA3 .

FIG. 8 is a flowchart of a volume control method according to an embodiment of the present invention.

Detailed ways

Please refer to FIG. 2 , which shows a block diagram of a volume control circuit 10 . The volume control circuit 10 includes a signal strength calculation circuit 11 , a low-pass filter 12 , a gain calculation circuit 13 , a buffer 14 and a volume adjustment circuit 15 . The signal strength calculation circuit 11 receives at least one channel data of at least one channel, and calculates a signal strength value VA1. The signal strength calculation circuit 11 includes calculation units 11a, 11b, an addition unit 11c and a multiplication unit 11d. The calculation units 11a and 11b respectively receive the channel data DA1 and the channel data DA2; the addition unit 11c is used to calculate the difference between the channel data DA1 and DA2. And, the multiplication unit 11d multiplies the sum of the channel data DA1 and DA2 obtained by the addition unit 11c by a parameter, such as a value of 0.5, to obtain a signal strength value VA1. In this embodiment, the left and right channel data are averaged value, you can avoid the situation where the volume of the two channels is uneven.

In response to the calculation time parameter TAV, the low-pass filter 12 performs a low-pass filtering operation on the signal strength value VA1 in a period of calculation time corresponding to the calculation time parameter TAV to obtain a signal strength value VA2 through calculation.

The gain calculation circuit 13 is used to refer to the adjustment condition Adj, and calculate the signal strength value VA2 to obtain the original gain value GA1; the buffer 14 temporarily stores the predetermined length of channel data DA1 and DA2; the volume adjustment circuit 15 generates an adjustment according to the original gain value GA1 gain value GA2, and adjust the channel data DA1 and DA2 stored in the buffer 13 according to the adjusted gain value, so as to generate adjusted channel data DA1' and DA2' respectively. In this way, the volume control circuit 10 can properly adjust the volume of the received channel data DA1 and DA2.

However, in order to have a good volume adjustment quality, in the circuit shown in FIG. 2 , it is necessary to increase the calculation time parameter TAV and reduce the bandwidth of the low-pass filter 12 . In this way, the volume control circuit 10 will need a long time to learn the change of the volume of the sound, so as to generate an adjustment gain value correspondingly to adjust the channel data DA stored in the buffer 14 . Therefore, if the size of the buffer 14 is not large enough, the volume cannot be adjusted in real time when the volume changes greatly. In this way, it will cause the user to feel uncomfortable when hearing too loud sound. Due to the large storage capacity of the buffer 14 required, the cost of the volume control circuit 10 will increase.

FIG. 3 is a block diagram of a volume control circuit according to an embodiment of the invention. The volume control circuit 20 includes a signal strength calculation circuit 21 , a low-pass filter 22 , an averager 23 , a gain calculation circuit 24 , a buffer 25 and a volume adjustment circuit 26 . In this embodiment, by using the averager 23, the problem of the volume control circuit 10 in FIG.

The signal strength calculation circuit 21 receives the channel data of i channels, and calculates the signal strength value VA1 according to it, where i is a natural number greater than 1. For example, i is equal to 2, and the channel data DA1 and DA2 on the two channels are left channel data and right channel data respectively. In this embodiment, the signal strength calculation circuit 21 includes calculation units 21a(1) and 21a(2), which are used to perform absolute value calculations on the channel data DA1 and DA2 respectively, so as to obtain the channel data abs[DA1 ] and abs[DA2].

The signal strength calculation circuit 21 also includes calculation units 21b and 21c, which are used to calculate the average value of the channel data abs[DA1] and abs[DA2] according to the channel data abs[DA1] and abs[DA2], and It is output as signal strength value VA1'. For example, the computing units 21b and 21c are computing units for performing addition operations and multiplication operations, respectively.

The low-pass filter 22 is used for low-pass filtering the signal strength value VA1' to generate the signal strength value VA2'. For example, the low-pass filter 22 is an infinite impulse response (Infinite Impulse Response, IIR) filter, including a delay unit 22a, adding units 22b, 22c and a multiplication unit 22d. The delay unit 22a is used to output the signal strength value VA2' of the previous time point to the addition units 22b and 22c; the addition unit 22b is used to calculate the difference between the signal strength value VA1' and the signal strength value VA2' of the previous time point; multiplication The unit 22d is used to multiply the difference obtained by the addition unit 22b with the calculation time parameter TAV' to obtain the second operation value; the addition unit 22c adds the second operation value to the signal strength value VA2' at the previous time point to obtain Obtain and output the current signal strength value VA2'.

The calculation time parameter TAV' is related to the cutoff frequency (cutoff frequency) of the low-pass filter 22 , that is, the time parameter TAV' is related to the time length for the low-pass filter 22 to perform the averaging operation. The smaller the calculation time parameter TAV' is, the shorter the average operation time of the low-pass filter 22 is, and the higher the cut-off frequency of the low-pass filter 22 is. For example, if the calculation time parameter TAV' corresponds to 100 ms, the low-pass filter 22 will roughly average the signal strength value VA1' within 100 ms to complete the low-pass filtering action.

The averager 23 is used to receive the signal strength value VA2', and perform an average operation on the signal strength value VA2' and M-1 signal strength values VA2' before the previous M-1 time points to obtain the signal strength value VA3, M is A natural number greater than 1. Preferably, the averager 23 includes a moving average (Moving Average) filter 23a and a sample-and-hold (sample-and-hold) unit 23b, and the averager 23 can be a weighted averager to provide a weighted average.

The moving average filter 23a is, for example, a finite impulse response (Finite Impulse Response, FIR) filter. Assuming that the M value is equal to 48, its transfer function (Transfer Function) H(z) is:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 48</span>}}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 47</span>}}<span\; class="notranslate">\; )</span>$

It can sum up and average the signal strength values VA2' after delays of 47, 46, 45, . . . and 0 cycle time to obtain a moving average value.

The sample-and-hold unit 23b is used for sampling the average value obtained by the moving average filter 23a every several time periods, so as to generate the signal strength value VA3.

The gain calculation circuit 24 is used for adjusting the signal strength value VA3 with reference to an adjustment condition Adj′ to obtain an adjusted signal strength value. The gain calculation circuit 24 calculates the original gain value GA1' according to the signal strength value VA3 and the adjusted signal strength value. For example, the gain calculation circuit 24 is used to determine whether the signal strength value VA3 is higher than a strength threshold value Vth, so as to adjust the signal strength value VA3. When the signal strength value VA3 is greater than the strength threshold value Vth, the gain operation circuit 24 generates the adjusted signal strength value substantially equal to the strength threshold value Vth; when the signal strength value VA3 is smaller than the strength threshold value Vth, the gain operation circuit 24 generates The value is substantially equal to the adjusted signal strength value which is j times the signal strength value VA3; the value j is a real number, such as the value 2.

For example, please refer to FIG. 4 , which shows an example of a gain relationship diagram of the gain calculation circuit 24 . The abscissa is the strength of the signal strength value VA3, and the vertical axis is the strength of the adjusted signal strength value VA3'. The curve 302 is the curve when the gain calculation circuit 24 is not adjusted, and the curve 304 is the curve after the gain calculation circuit 24 is adjusted. As shown in FIG. 4 , it is assumed that the intensity threshold Vth is equal to -18 decibels (Decibel, dB), and j is equal to 2. In this way, when the signal strength value VA3 is less than -18dB, the gain operation circuit 24 generates the adjusted signal strength value which is substantially equal to twice the signal strength value VA3, that is, the adjusted signal strength value is equal to the signal strength value Add 6 decibels (dB) to the value VA3. When the signal strength value VA3 is greater than -18dB, the adjusted signal strength value generated by the gain calculation circuit 24 is always -18dB.

The gain operation circuit 24 generates the original gain value GA1' according to the equation:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="GA"\; filenames="H2010100035746E00031.png"\; state="\{\{state\}\}">GA</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; VA</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{\mathrm{<span\; class="notranslate">\; VA</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}$

Wherein VA3' is the adjusted signal strength value, accordingly, the gain calculation circuit 24 calculates and generates the original gain value GA1' according to the signal strength value VA3 and the adjusted signal strength value.

The buffer 25 includes buffer units 25a and 25b for temporarily storing the channel data DA1 and DA2 respectively. The volume adjustment circuit 26 generates an adjusted gain value GA2' according to the original gain value GA1', and adjusts the channel data DA1 and DA2 stored in the buffer 25 according to the adjusted gain value GA2' to generate adjusted channel data DA1 respectively. ' and DA2'.

The volume adjustment circuit 26 includes a convergence calculation unit 26a and a gain change rate detection unit 26b. The gain change rate detection unit 26b is used to receive the original gain value GA1', and according to the relationship between the original gain value GA1' and the previous original gain value, determine whether the change trend of the original gain value GA1' is from large to small or from From small to large, to know whether the volume corresponding to the channel data DA1 and DA2 is from small to large, or from large to small, and correspondingly use the gradually increasing convergence parameter AT or gradually decreasing convergence parameter RT as the convergence parameter Pc output. The convergence calculation unit 26a calculates the adjusted gain value GA2' according to the convergence parameter Pc and the original gain value GA1'.

Furthermore, the gain change rate detection unit 26b includes a delay unit 26b1, an addition unit 26b2, a hysteresis (Hysteresis) operational amplifier 26b3 and a multiplexer (Multiplexer) unit 26b4; the delay unit 26b1 is used to output the previous original gain value GA1' to the addition unit 26b2; the addition unit 26b2 calculates the difference ΔG between the previous original gain value GA1' and the original gain value GA1'; the hysteresis operational amplifier 26b3 is used to receive the difference ΔG to generate a hysteresis control signal SC.

Please refer to FIG. 5 , which shows an input-output relationship diagram of the hysteresis operational amplifier of this embodiment. When the difference ΔG is greater than the high threshold Gth1, the hysteresis operational amplifier 26b3 judges that the variation trend of the difference ΔG is from small to large, and generates a hysteresis control signal SC of the first level. When the difference ΔG is smaller than the low threshold Gth2, the hysteresis operational amplifier 26b3 judges that the variation trend of the difference ΔG is from large to small, and generates a hysteresis control signal SC of a second level. When the difference ΔG is between the critical values Gth1 and Gth2, the hysteresis operational amplifier 26b3 does not change the level of the hysteresis control signal SC.

The multiplexer unit 26b4 responds to the hysteresis control signal SC of the first level, selects the gradually increasing convergence parameter AT as the output of the convergence parameter Pc; and responds to the hysteresis control signal SC of the second level, selects the gradually decreasing convergence parameter RT is output as the convergence parameter Pc. Preferably, the values of the increasing convergence parameter AT and the decreasing convergence parameter RT may be different.

The convergent computing unit 26a includes adding units 26a1, 26a2, a multiplying unit 26a3, and a delay unit 26a6. The delay unit 26a6 is used to output the previous adjusted gain value GA2' to the adding units 26a1 and 26a2. The addition unit 26a1 is used to generate the difference between the current original gain value GA1' and the current adjusted gain value GA2'; the multiplication unit 26a3 multiplies the difference provided by the addition unit 26a1 by the convergence parameter Pc to obtain the difference after the convergence operation value. The adding unit 26a2 adds the converged difference to the previous adjustment gain value GA2' to generate the current adjustment gain value GA2'.

The volume adjustment circuit 26 also includes multiplication units 26a4 and 26a5, and the multiplication units 26a4 and 26a5 receive the channel data DA1 and DA2 temporarily stored in the buffer 25 respectively, and respectively adjust the channel data DA1 and DA2 according to the adjustment gain value GA2′ The adjustment is performed to generate adjusted channel data DA1 ′ and DA2 ′ respectively; the channel data DA1 and DA2 are adjusted according to the corresponding adjustment gain value GA2 ′. That is, if the channel data DA1 and DA2 currently output by the buffer units 25a and 25b are the channel data DA1 and DA2 input to the computing units 21a(1) and 21a(2) at the time point t, it is used to adjust The adjusted gain value GA2' of the channel data DA1 and DA2 is generated based on the channel data DA1 and DA2 input to the computing units 21a(1) and 21a(2) at the time point t.

In this embodiment, the volume control circuit 20 is used to generate a corresponding adjustment gain value GA2' to adjust the channel data DA1 and DA2 when the signal strength of the corresponding channel data DA1 and DA2 has a specific trend of change. The signal strengths of the channel data DA1 and DA2 are made to be within a certain range.

Please refer to Figure 1 again. As mentioned above, the volume control circuit 10 in FIG. 1 must increase the calculation time parameter TAV to reduce the bandwidth of the low-pass filter 12 in order to have a good volume adjustment quality. However, this will increase the required storage capacity of the buffer 14 . However, if the calculation time parameter TAV in Fig. 1 is directly reduced and the bandwidth of the low-pass filter 12 is increased to reduce the storage capacity of the required buffer 14, the signal strength value VA2 output by the low-pass filter 12 may be generated The large oscillation causes the volume adjustment circuit 15 to make a misjudgment, resulting in a wrong adjustment gain value and the problem that the channel data DA1 and DA2 cannot be adjusted correctly.

For example, the waveform diagrams of the sound signal SA1 and the signal strength value VA1 corresponding to the channel data DA1 are shown in FIG. 6A and FIG. 6B , respectively. When the strength of the sound signal SA1 changes from small to large, the signal strength value VA1 will oscillate and jitter.

The volume control circuit 20 in FIG. 3 of this embodiment has a smaller calculation time parameter TAV' and a higher bandwidth of the low-pass filter 12, so a large amount of storage capacity of the buffer 14 is not required. In order to prevent the volume control circuit 20 of FIG. 2 from producing jitters similar to the above-mentioned signal strength value VA1 with large oscillations, resulting in misjudgment by the volume adjustment circuit 15, the volume control circuit of FIG. 3 in this embodiment In 20, an averager 23 is provided to average the signal strength value VA2' generated by the low-pass filter 22 to obtain the signal strength value VA3.

For example, one of the waveform diagrams of the signal strength values VA3 and VA2' is shown in FIG. 7 . After the signal strength value VA2' is calculated by the averager 23, the signal strength value VA3 can be obtained with a relatively moderate degree of strength change and no large-scale oscillation phenomenon, which allows the volume control circuit 20 of this embodiment to quickly generate a response when encountering a large volume change. Adjust the gain value to adjust the volume, shorten the delay time required for automatic volume adjustment, and reduce the storage capacity of the buffer used to achieve high-quality sound processing and reduce costs.

In this embodiment, the values of the high and low thresholds Gth1 and Gth2 of the hysteresis operational amplifier 26b3 are relative to the degree of intensity variation fluctuation of the original gain value GA1'. Preferably, when the jitter of the original gain value GA1' is serious, the transition critical values Gth1 and Gth2 of the hysteresis operational amplifier 26b3 need to be higher values, so as to avoid misjudgment of the change trend of the channel data DA1 and DA2 ; and when the fluctuation range of the original gain value GA1 ′ is relatively small, the transition thresholds Gth1 and Gth2 can be correspondingly set to lower values.

In this embodiment, the M value of the moving average filter 23a can also be adjusted according to the state of the signal strength value VA2'. Although only the case where the value M is equal to 48 is used as an example for illustration, the averager of this embodiment 23 The number of reference signal strength values VA2' is not limited to the value M, but can be other values. The selection of the values of the transition thresholds Gth1 and Gth2 may also be related to the value M.

The present invention also proposes a volume control method for generating and adjusting gain values to adjust multiple pieces of channel data of multiple channels. Please refer to FIG. 8 , which shows a flowchart of a volume control method according to an embodiment of the present invention. In step S800, a first signal strength value corresponding to the signal strength of the channel data is generated. Next, in step S810, a low-pass filter operation is performed on the first signal strength value to generate a second signal strength value. Then, in step S820, the second signal strength value and the first M-1 second signal strength values of the previous M-1 time points are averaged to obtain a third signal strength value, where M is a natural number greater than 1 . Next, in step S830, referring to the adjustment condition, the original gain value is obtained according to the third signal strength value. Then, in step S840, use the buffer to temporarily store the channel data. After that, in step S850, an adjusted gain value is generated according to the original gain value, and the channel data stored in the buffer is adjusted according to the adjusted gain value.

The operating principle of the above volume control method has been described in detail in the volume control circuit 20 , so it will not be repeated here.

The present invention properly sets the weighted averager in the volume control circuit, so that the calculation time parameter of the low-pass filter of the present invention can be shortened, and the storage capacity of the register unit in the buffer can be greatly reduced. In this way, compared with the traditional volume control circuit, the volume control circuit of the present invention has the advantages of low cost and fast convergence of volume adjustment to prevent popping.

To sum up, although the present invention has been disclosed by the above embodiments, they are not intended to limit the present invention. Those skilled in the art to which the present invention belongs may make various equivalent changes or substitutions without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the appended claims of the application.

Claims (15)

1. a volume control circuit is adjusted many channel datas that yield value is adjusted a plurality of sound channels in order to produce one, and this volume control circuit comprises:

One signal strength signal intensity computing circuit is in order to receive and to produce one first signal strength values of the signal strength signal intensity that corresponds to these many channel datas;

One low pass filter is in order to carry out low-pass filtering operation to this first signal strength values, to produce a secondary signal intensity level;

One weighted average device in order to receiving this secondary signal intensity level, and averages computing to preceding M-1 secondary signal intensity level of this secondary signal intensity level and a preceding M-1 time point, and to obtain one the 3rd signal strength values, M is the natural number greater than 1;

One gain computing circuit is in order to reference one regularization condition, according to the 3rd signal strength values, to obtain an original gain value;

One buffer is in order to temporary these many channel datas; And

One volume is adjusted circuit, in order to producing this adjustments yield value according to this original gain value, and adjusts this many channel datas according to this adjustment yield value, and wherein this volume adjustment circuit comprises:

One change in gain rate detecting unit, in order to receive this original gain value, and according to the magnitude relationship of this original gain value and last original gain value, the serve as reasons little increase or by reducing greatly, decrescence to restrain parameter as a convergence parameter with a cumulative convergence parameter or accordingly of the variation tendency of judging this original gain value;

One convergence arithmetic element in order to receiving this original gain value, and obtains this adjustment yield value according to last original gain value, this original gain value and this convergence parameter computing.

2. volume control circuit according to claim 1 is characterized in that, this weighted average device comprises:

One moving average filter is in order to carry out the rolling average computing to this secondary signal intensity level, to produce an average intensity value; And

One sampling keeping unit is in order to take a sample to this average intensity value, to obtain the 3rd signal strength values.

3. according to the volume control circuit shown in the claim 2, it is characterized in that this moving average filter is a finite impulse response filter, and this low pass filter is an infinite impulse response filter.

4. volume control circuit according to claim 1 is characterized in that, this regularization condition is a critical value, and whether this gain computing circuit is in order to judge the 3rd signal strength values greater than this critical value, to determine this original gain value.

5. volume control circuit according to claim 4, it is characterized in that, when this gain computing circuit is used to the 3rd signal strength values less than this critical value, the 3rd signal strength values is amplified a prearranged multiple producing one the 4th signal strength values, and this gain computing circuit produces this original gain value according to the ratio of the 4th signal strength values and the 3rd signal strength values.

6. volume control circuit according to claim 4, it is characterized in that, when this gain computing circuit is used to the 3rd signal strength values greater than this critical value, the 3rd signal strength values is restricted to this critical value producing one the 4th signal strength values, and this gain computing circuit produces this original gain value according to the ratio of the 4th signal strength values and the 3rd signal strength values.

7. volume control circuit according to claim 1 is characterized in that, this change in gain rate detecting unit comprises:

One difference arithmetic element in order to receiving this original gain value and last original gain value, and is calculated a difference of this original gain value and last original gain value;

One sluggish operational amplifier, in order to receiving this difference, and the corresponding hysteresis control signal that produces; And

One multiplexer module, in order to receive should be cumulative and this decrescence restrain parameter, and in response to this hysteresis control signal come with this cumulative and this decrescence restrain parameter one of them exported as this convergence parameter.

8. volume control circuit according to claim 7 is characterized in that, the critical value of this sluggishness operational amplifier is the size that is relevant to numerical value M.

9. volume control circuit according to claim 1 is characterized in that, this volume is adjusted circuit and also comprised:

A plurality of arithmetic elements are respectively in order to carry out multiplying with these channel datas and this adjustment yield value, to produce these channel datas after many styles are put in order accordingly.

10. a method for controlling volume is adjusted many channel datas that yield value is adjusted a plurality of sound channels in order to produce one, and this method for controlling volume comprises:

A. produce one first signal strength values of the signal strength signal intensity that corresponds to these many channel datas;

B. this first signal strength values is carried out low-pass filtering, to produce a secondary signal intensity level;

C. preceding M-1 secondary signal intensity level to this secondary signal intensity level and a preceding M-1 time point is weighted average calculating operation, and to obtain one the 3rd signal strength values, M is the natural number greater than 1;

D. with reference to a regularization condition, obtain an original gain value according to the 3rd signal strength values;

E. keep in these many channel datas; And

F. produce this adjustment yield value according to this original gain value, and adjust these many channel datas of being kept in according to this adjustment yield value, wherein this step f comprises:

According to the magnitude relationship of this original gain value and last original gain value, the serve as reasons little increase or by reducing greatly of the variation tendency of judging this original gain value decrescence restrains parameter as a convergence parameter to select a cumulative convergence parameter or accordingly; And

Obtain this adjustment yield value according to this original gain value, last original gain value and this convergence parameter computing.

11. method for controlling volume according to claim 10 is characterized in that, in step c, is to use a moving average filter to average computing.

12. the volume control circuit according to shown in the claim 11 is characterized in that, in this step b, be to carry out low-pass filtering by an infinite impulse response filter, and this moving average filter is a finite impulse response filter.

13. method for controlling volume according to claim 10 is characterized in that, steps d comprises:

When the 3rd signal strength values during less than a critical value, the 3rd signal strength values is amplified a prearranged multiple, to produce one the 4th signal strength values; And

Ratio according to the 3rd signal strength values and the 4th signal strength values produces this original gain value.

14. method for controlling volume according to claim 10 is characterized in that, steps d comprises:

When the 3rd signal strength values during greater than a critical value, the 3rd signal strength values is restricted to this critical value, to produce one the 4th signal strength values; And

Ratio according to the 3rd signal strength values and the 4th signal strength values produces this original gain value.

15. method for controlling volume according to claim 10 is characterized in that, step f carries out multiplying with these channel datas and this adjustment yield value, to produce the whole back of many styles channel data accordingly.

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