JP2000341786A - Electronic volume switching method and electronic volume switching device - Google Patents

Abstract

(57) [Problem] To provide an electronic volume switching device capable of reducing generation of noise at the time of volume switching. SOLUTION: In an electronic volume switching device 1 for switching a volume of an output audio signal by switching an attenuation coefficient input to an attenuator 22, an attenuation coefficient input to a coefficient interpolation unit 13 is switched by an operation from an operator. In this case, the coefficient interpolating unit 13 interpolates the attenuation coefficient before and after the switching, and sequentially provides the attenuator 22 with the attenuation coefficient that gradually transitions to the attenuation coefficient after the switching. As a result, even when the number of switching stages of the volume is relatively small, it is possible to reduce the occurrence of noise at the time of switching the volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic volume switching method and an electronic volume switching device for electrically switching a volume (volume), and is connected to various electronic devices such as a computer system and an audio device. Used for devices that generate audio signals.

[0002]

2. Description of the Related Art FIG. 13 is a block diagram showing an example of a conventional electronic volume switching device 900. The electronic volume switching device 900 is a device that attenuates an input audio signal and outputs an output audio signal. The electronic volume switching device 900 receives a control signal based on a volume switching operation performed by an operator, and switches a transmission destination of the input audio signal, and a selector 901. It has a plurality of attenuators 902 for attenuating audio signals. Each attenuator 902
The coefficients corresponding to a plurality of attenuation (hereinafter, referred to as "damping _{coefficient".) A 1, A 2,} ···, attenuating the input voice signal in accordance with any one of A _m.

With such a configuration, when the operator performs an operation of switching the volume, the selector 9 is controlled by a control signal.
01 is switched, the input audio signal is guided to the desired attenuator 902, and the volume of the output audio signal is switched.

[0004]

However, the electronic volume switching device 900 having such a configuration has a problem that noise is generated when the volume is switched.

FIG. 14 shows an electronic volume switching device 900.
FIG. 15 is a graph showing an example of an input audio signal (ie, a signal before attenuation) to the input device, and FIG. 15 is a graph showing a state of an output audio signal from the electronic volume switching device 900 with respect to the input audio signal of FIG. In the graph shown in FIG. 15, the volume attenuation is switched at time T1 by the volume switching operation of the electronic volume switching device 900.

As shown in FIG. 15, when the number of steps for switching the amount of attenuation of the volume is not sufficiently large (for example, in the case of about 30 steps), the amount of attenuation is instantaneously switched according to a control signal from the operator. And an abrupt change in the amplitude direction of the output audio signal occurs, which may cause noise (so-called step noise).

On the other hand, it is necessary to provide a large number of attenuators 902 in FIG. 13 in order to increase the number of switching stages of the amount of attenuation to suppress a rapid change in the output audio signal. Further, the operator needs to repeatedly perform the UP / DOWN operation of the selector many times, which causes a problem that operability is deteriorated.

The present invention has been made in view of the above problems, and has as its object to reduce noise generated at the time of volume switching without increasing the number of volume switching stages.

[0009]

According to the first aspect of the present invention, there is provided an electronic volume switching method for electrically switching a volume which changes according to a damping coefficient, wherein (a) a first damping coefficient before switching and a second damping coefficient after switching. Interpolating between the two attenuation coefficients to obtain an output attenuation coefficient, and (b) outputting the output audio signal by applying the output attenuation coefficient to the input audio signal in accordance with the output timing; c) repeating the steps (a) and (b) to gradually transition the output attenuation coefficient from the first attenuation coefficient to the second attenuation coefficient, thereby gradually switching the volume of the output audio signal. Have.

According to a second aspect of the present invention, there is provided the electronic volume switching method according to the first aspect, wherein (d) a transition period for transitioning the output attenuation coefficient from the first attenuation coefficient to the second attenuation coefficient. The method further includes a setting step.

According to a third aspect of the present invention, there is provided the electronic volume switching method according to the first or second aspect, wherein (e) the step (c).
When the target attenuation coefficient is further switched during the execution of the above, the latest output attenuation coefficient is set as a new first attenuation coefficient, and the target attenuation coefficient after switching is set as a new second attenuation coefficient.
The method further includes the step of executing the step (c) as a damping coefficient.

According to a fourth aspect of the present invention, there is provided the electronic volume switching method according to the first or second aspect, wherein (f) the step (c).
If the target damping coefficient is further switched during the execution of the above, the second damping coefficient is set as a new first damping coefficient after the completion of the step (c), and the target damping coefficient after the switching is newly set. A step of executing the step (c) as a suitable second damping coefficient.

According to a fifth aspect of the present invention, there is provided the electronic volume switching method according to any one of the first to fourth aspects, wherein the digital LP filter to which the first attenuation coefficient has been input in the step (a). The second attenuation coefficient is input, and the output from the digital LP filter is used as the output attenuation coefficient.

According to a sixth aspect of the present invention, there is provided an electronic volume switching device for electrically switching a volume that changes in accordance with an attenuation coefficient, wherein interpolation is performed between a first attenuation coefficient before switching and a second attenuation coefficient after switching. Interpolating means for sequentially obtaining an output attenuation coefficient that gradually transitions from the first attenuation coefficient to the second attenuation coefficient, and an output audio signal that is sequentially applied to the input audio signal in accordance with output timing. And output means for outputting

According to a seventh aspect of the present invention, in the electronic volume switching device according to the sixth aspect, means for setting a transition period in which the output attenuation coefficient transitions from the first attenuation coefficient to the second attenuation coefficient. Is further provided.

According to an eighth aspect of the present invention, there is provided the electronic volume switching device according to the sixth or seventh aspect, wherein a target attenuation coefficient is further switched while the interpolation means sequentially obtains the output attenuation coefficient. Then, the interpolation means performs interpolation using the latest output attenuation coefficient as a new first attenuation coefficient and the target attenuation coefficient after switching as a new second attenuation coefficient.

According to a ninth aspect of the present invention, there is provided the electronic volume switching device according to the sixth or seventh aspect, wherein a target attenuation coefficient is further switched while the interpolation means sequentially obtains the output attenuation coefficient. The apparatus further includes means for stopping input of the switched target attenuation coefficient to the interpolation means until the output attenuation coefficient becomes substantially the second attenuation coefficient.

According to a tenth aspect of the present invention, in the electronic volume switching device according to any one of the sixth to ninth aspects, the interpolation means includes a digital LP filter.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing a configuration of an electronic volume switching device 1 according to the present invention. As shown in FIG. 1, an electronic volume switching device 1
Is an up-down counter 11 that receives a control signal according to the operation of the operator and raises or lowers a value held therein, and a coefficient output that outputs a damping coefficient in the coefficient table 12a using the value from the up-down counter 11 as an index. Part 1
2, and a coefficient interpolating unit 13 for obtaining an attenuation coefficient according to a change in the attenuation coefficient from the coefficient output unit 12.

The audio signal is processed in accordance with the attenuation coefficient. The analog-to-digital converter 21 converts an analog input audio signal into a digital input signal. The digital input signal is attenuated using the attenuation coefficient from the coefficient interpolation unit 13. And an attenuator 2 for outputting an attenuated digital output signal
2, and a digital-to-analog converter 23 that converts a digital output signal into an analog signal and outputs an output audio signal.

The coefficient table 12a includes a number of attenuation coefficients A ₀ , A ₁ ,
A ₂ ,..., _Am are stored. The attenuation coefficient is an index value for performing attenuation in the attenuator 22, and the attenuator 22
An arbitrary mode of the attenuation coefficient may be adopted according to the processing method of (1). For example, when the attenuation process is performed by multiplying the digital input signal by the attenuation coefficient by the attenuator 22, a multiplication coefficient is used as the attenuation coefficient, and the attenuator 22 performs the attenuation process according to the decibel value. In this case, a decibel value is used as the attenuation coefficient.

Next, the operation of the electronic volume switching device 1 will be described with reference to FIG. FIG. 2 is a flowchart showing an example of an outline of an operation when the damping coefficient is switched by the control signal in the electronic volume switching device 1. Before the attenuation coefficient is switched, the attenuation coefficient before switching (hereinafter, referred to as “first attenuation coefficient”) is constantly supplied from the coefficient output unit 12 to the attenuator 22 via the coefficient interpolation unit 13. , The input audio signal is attenuated according to the first attenuation coefficient and output as an output audio signal. That is, the state is substantially the same as the state where the coefficient interpolation unit 13 does not function.

When there is an operation input for switching the volume from the operator, the value held by the up / down counter 11 is changed based on the control signal, and the attenuation coefficient after switching (hereinafter, referred to as "second attenuation coefficient") is a coefficient. It is provided to the interpolation unit 13. In response, the coefficient interpolation unit 13 performs interpolation between the first attenuation coefficient and the second attenuation coefficient (step S1).
1).

In the case of the operation flow shown in FIG. 2, the interpolation operation is repeatedly performed as described later, and the value of the attenuation coefficient (hereinafter referred to as "output attenuation coefficient") generated by the interpolation is the attenuator 22. (Hereinafter referred to as “output timing”). That is, the output attenuation coefficient immediately after switching the volume is the first.
The output attenuation coefficient is set to a value close to the attenuation coefficient, and the subsequent output attenuation coefficient is set to a value gradually approaching the two attenuation coefficient.

The output attenuation coefficient generated by the coefficient interpolation unit 13 is provided to the attenuator 22 in accordance with the output timing. Thus, after the output attenuation coefficient is applied to the digital input signal, the digital output signal is converted into an analog signal and the output audio signal is output (step S12).

The interpolation and output of the attenuation coefficient as described above are repeatedly performed, and the attenuation coefficient applied to the attenuator 22 gradually transitions from the first attenuation coefficient to the second attenuation coefficient (step S13). That is, the coefficient interpolating unit 13 sets the output attenuation coefficient output immediately after switching the volume to a value close to the first attenuation coefficient, and then interpolates the first attenuation coefficient and the second attenuation coefficient according to the output timing. Second
An output attenuation coefficient that gradually transitions to an attenuation coefficient is sequentially output.

When the transition of the output attenuation coefficient to the second attenuation coefficient is substantially completed, the switching of the volume ends, and thereafter, the attenuator 22 is constantly supplied with the second attenuation coefficient. That is, the coefficient interpolating unit 13 does not substantially function.

FIGS. 3 and 4 are graphs for explaining the effect obtained by interpolation of the attenuation coefficient. In these figures, symbols W1 and W2 indicate waveforms of output audio signals corresponding to the first attenuation coefficient and the second attenuation coefficient, respectively, and symbol T1 indicates a time at which the attenuation coefficient is switched. Further, a solid broken line indicated by a reference sign W3 in FIG. 3 shows a waveform of the output audio signal when the interpolation of the attenuation coefficient is not performed. As shown in FIG. 3, when the attenuation coefficient is switched at time T11, the output audio signal changes greatly, and noise occurs.

On the other hand, a smooth solid line indicated by reference numeral W4 in FIG. 4 shows a waveform of the output audio signal when the attenuation coefficient is interpolated. As shown in FIG. 4, when the attenuation coefficient is interpolated, the waveform W4 gradually transitions from the waveform W1 to the waveform W2 after time T11, and the generation of noise is suppressed. In FIG. 4, the switching of the attenuation coefficient is completed at time T12, and a period during the transition from time T11 to time T12 is referred to as a “transition period” in the following description.

Next, a specific configuration of the coefficient interpolation unit 13 for realizing the operation shown in FIG. 2 will be described. FIG. 5 is a block diagram showing an example of the configuration of the coefficient interpolation unit 13.

The coefficient interpolation unit 13 shown in FIG.
A filter FIR has a configuration using a (finite impulse response) filter, a delay unit array 31 the delay time has by connecting a plurality of delay units 31a of the T ₀ in series, the multiplication having a plurality of multipliers 32a Vessel array 32,
And an adder 33 for calculating the sum of outputs from the multipliers 32a. Further, an input signal or an output signal to each delay unit 31a is input to each multiplier 32a.

[0032] In the example shown in FIG. 5, the multiplication coefficient k _0, k _1, k ₂ of each of the multipliers 32a, · · ·, k _n is

[0033]

(Equation 1)

When a predetermined attenuation coefficient is constantly input, the attenuation coefficient is output from the adder 33. That is, unless the attenuation coefficient input to the coefficient interpolation unit 13 is changed, the attenuation coefficient input from the coefficient interpolation unit 13 is output as it is, which is equivalent to a state where the interpolation operation is not substantially performed.

Here, all the multiplication coefficients are

[0036]

(Equation 2)

Assuming that the damping coefficient is
e, ie, the first damping coefficient A
When the second attenuation coefficient Ae is input to the coefficient interpolation unit 13 to which s has been input, the output attenuation coefficient output from the coefficient interpolation unit 13 changes as follows.

First, at the stage before the second attenuation coefficient Ae is input, the input and output to all the delay units 31a are the first attenuation coefficient As, so the output from the coefficient interpolation unit 13 is

[0039]

(Equation 3)

## EQU4 ##

Here, the second attenuation coefficient A is added to the coefficient interpolation unit 13.
When e is input, the output from the coefficient interpolation unit 13 is

[0042]

(Equation 4)

When one unit delay time (time T ₀ ) elapses, the first two delay units 31a receive the second delay time.
Since the attenuation coefficient Ae is input, the output from the coefficient interpolation unit 13 is

[0044]

(Equation 5)

Is as follows. Then, the number of the delay units 31a is set to n
When the time elapses by n · T ₀ after the switching of the attenuation coefficient, the input and the output to all the delay units 31a become the second attenuation coefficient Ae, and the output from the coefficient interpolation unit 13 becomes

[0046]

(Equation 6)

Is as follows.

By performing the operations described above, the attenuation coefficient given to the attenuator 22 by the coefficient interpolation unit 13 shown in FIG. 5 can be finely interpolated, and the volume attenuation amount of the electronic volume switching device 1 can be reduced. Noise at the time of volume switching can be reduced without increasing the number of switching stages. In the case of the configuration shown in FIG.
Time n · T ₀ is the transition period.

Also, a digital LP is used as the coefficient interpolation unit 13.
By using a filter, the coefficient interpolation unit 13 can be easily realized.

Next, the first damping coefficient As is constantly input.
The second damping coefficient Ae ₁Is switched to
During the transition period in which the interpolation by the coefficient interpolation unit 13 is performed,
Target attenuation coefficient Ae_TwoIf switched to
explain about. FIG. 6 shows a new damping factor A during the transition period.
e_TwoSuppress noise even when input
5 is a flowchart illustrating an outline of an operation.

In the flow of the operation shown in FIG. 6, while the transition of the damping coefficient from the first damping coefficient As to the second damping coefficient Ae ₁ is performed, the same processing as the processing shown in FIG. 2 is performed. Will be That is, the first damping coefficient As and the second damping coefficient A
interpolating between e ₁ is performed, output attenuation coefficient obtained are sequentially output to the attenuator 22 (step S21~S2
3).

Here, when the new attenuation coefficient Ae ₂ is input to the coefficient interpolation unit 13 (step S24), thereafter, interpolation is performed between the latest output attenuation coefficient and the new attenuation coefficient Ae _2. Then, the output attenuation coefficient is obtained. That is, interpolation is performed by the coefficient interpolation unit 13 with the latest output attenuation coefficient as a new first attenuation coefficient and the new attenuation coefficient Ae ₂ as a new second attenuation coefficient (step S).
25).

By such processing, a new attenuation coefficient A
When e ₂ is input, the output attenuation coefficient thereafter gradually transitions to a new attenuation coefficient Ae ₂ . Thus, even if the attenuation coefficient is switched during the transition period, generation of noise is suppressed.

The coefficient interpolation unit 13 shown in FIG. 5 can realize substantially the same operation as the operation shown in FIG. For example, each multiplier coefficient is assumed to be the values shown in Equation 2, the first damping coefficient As is switched from state being input constantly to the second damping coefficient Ae _1, 2 unit delay time from the switching ( After 2 × T ₀ ), a new attenuation coefficient A is obtained.
If e ₂ is input, the output attenuation coefficient at the time of switching to the second attenuation coefficient Ae ₁ is:

[0055]

(Equation 7)

After one unit delay time elapses from the switching, the output attenuation coefficient becomes

[0057]

(Equation 8)

Is as follows. Then, after a lapse of two unit delay times from the switching, a new attenuation coefficient Ae ₂ is input, and the output attenuation coefficient becomes

[0059]

(Equation 9)

, And in the following order

[0061]

(Equation 10)

Is obtained. As described above, in the coefficient interpolation unit 13 shown in FIG. 5, after being switched to the new attenuation coefficient Ae ₂ , the output attenuation coefficient immediately before the switching and the new attenuation coefficient Ae ₂
Is output as the output attenuation coefficient, and interpolation is performed substantially between the attenuation coefficient immediately before switching and the attenuation coefficient Ae ₂ . As a result, even after the new attenuation coefficient Ae ₂ is input, the output audio signal is smoothly changed to the new attenuation coefficient Ae _2.
Shifts to the output corresponding to. As a result, generation of noise is suppressed.

In the above description, the multiplication coefficients are all assumed to be equal. However, by changing the multiplication coefficients while satisfying the condition shown in Equation 1, the transition characteristics of the output audio signal at the time of switching the attenuation coefficient are changed. Can be changed. Alternatively, a plurality of patterns of combinations of multiplication coefficients may be prepared in advance, and the patterns may be switched as appropriate.

Next, another configuration example of the coefficient interpolation unit 13 will be described. FIG. 7 shows another example of the coefficient interpolation unit 13, which is a digital LP filter IIR (infinite impulse response).
FIG. 4 is a block diagram showing a configuration using a sponse) filter. In the coefficient interpolating unit 13, the input attenuation coefficient is returned through the multiplier 34 of the multiplication coefficient k, and then through the delay unit 35, the multiplier 36 of the multiplication coefficient (1-k), and the adder 37. . As a result, when a constant attenuation coefficient is continuously input, this attenuation coefficient is output as an output attenuation coefficient, and when the attenuation coefficient is switched, an output attenuation coefficient that gradually transitions to the switched attenuation coefficient is obtained. Can be That is, the configuration shown in FIG. 7 realizes substantially the same operation as the operation shown in FIG. 2 when the attenuation coefficient is switched. As a result, it is possible to reduce noise generated when the volume attenuation is switched.

After the switching of the damping coefficient, before the switching of the damping coefficient is completed, that is, when the switching to the new target damping coefficient is performed during the transition period. , The output attenuation coefficient gradually changes from the latest output attenuation coefficient to a new attenuation coefficient. Thereby, an operation substantially similar to the operation shown in FIG. 6 is also realized. As a result, it is possible to suppress the generation of noise even when the attenuation of the volume is switched during the transition period.

Embodiment 2 FIGS. 8 and 9 are block diagrams showing a configuration in which a transition period changing unit 41 is added as a configuration for appropriately changing the transition period to the coefficient interpolation unit 13 shown in FIGS. 5 and 7, respectively.

In the case of the configuration shown in FIG.
“1” is set to 0 as a multiplication coefficient of a part of the plurality of multipliers 32 a of the multiplier array 32 on the side opposite to the input side. For example,
While satisfying the condition shown in Equation 1,

[0068]

[Equation 11]

Assume that As a result, the number of the delay units 31a is equivalent to a state where the number is changed from (n + 1) to (p + 1), and the transition period is changed from n · T ₀ to p · T ₀ .

Further, in the case of the example shown in FIG. 9, the transition period changing unit 41 calculates k in the multiplication coefficient of the two multipliers 34 and 36.
Is increased or decreased between 0 and 1. When the value of k is increased, the transition period becomes shorter, and when the value of k is decreased, the transition period becomes longer.

The setting (or changing) of the transition period may be performed before the volume is switched, or may be performed in response to the volume switching.
Further, it may be performed during the transition of the attenuation coefficient within a range that does not cause noise. That is, the transition period may be set at any timing. On the other hand, the transition period may be fixed to a predetermined value in advance. 5 and 7 show examples in which the setting of the transition period is fixed in advance.

FIG. 10 is a flowchart illustrating the flow of the operation when the transition period is set when the volume is switched. Note that FIG. 10 shows only the part including the operation of setting the transition period in the operation of FIG. 6, and the other parts are the same as those of FIG.

In the example shown in FIG. 10, when the attenuation coefficient is switched, a transition period is set before the interpolation by the coefficient interpolation unit 13 is performed (step S31). The set transition period is set, for example, to be longer as the difference between the first attenuation coefficient and the second attenuation coefficient is larger. As a result, the transition period becomes longer as the amount of attenuation of the volume is switched to a larger value, and the occurrence of noise is appropriately prevented.

If the new attenuation coefficient is switched during the transition period (step S25), the transition period is set again (step S31). Then, the interpolation by the coefficient interpolation unit 13 is performed based on the reset transition period (step S21).

As described above, the transition period of the coefficient interpolation unit 13 can be changed by changing the multiplication coefficient of the digital LP filter, and can be changed according to the operating conditions of the electronic volume switching device 1 and the switching conditions of the attenuation coefficient. The transition period can be set appropriately. A plurality of patterns of combinations of multiplication coefficients may be prepared in advance, and the transition period may be switched as appropriate.

Embodiment 3 FIG. 11 is a block diagram showing a third embodiment of the electronic volume switching device 1 according to the present invention. Electronic volume switching device 1 shown in FIG.
Is similar to the configuration shown in FIG. 1 except that a delay circuit 51 is provided at a stage before the coefficient interpolation unit 13.

The transition period is input from the coefficient interpolation unit 13 to the delay circuit 51. When the attenuation coefficient from the coefficient output unit 12 is switched, the switching to the coefficient interpolation unit 13 is continued until the transition period elapses. Continue to output the previous attenuation coefficient. That is, even if a new attenuation coefficient is input again during the transition period, the switching of the attenuation coefficient is stopped so that the new attenuation coefficient is not passed to the coefficient interpolation unit 13 until the transition period elapses. .

FIG. 12 is a flowchart showing the flow of the operation of such an electronic volume switching device 1. Note that the transition period can be changed also in FIG. 12, and at the same timing as the operation illustrated in FIG.
A case where a transition period is set at the time of volume switching is illustrated.

First, when the volume is switched, a transition period is set as needed (step S41). After that, during the transition period, the same operation as in FIG. 2 is performed until the transition period elapses, regardless of whether or not the volume is further switched. That is, interpolation is performed between the original first damping coefficient and the switched second damping coefficient in accordance with the output timing (step S42).
An output audio signal is output based on the obtained output attenuation coefficient (step S43), and these processes are repeated until the transition of the output attenuation coefficient is completed (step S44).

If the target attenuation coefficient has been newly set during the transition period, the volume switching operation is performed again from the beginning (step S45). That is, the interpolation is performed by setting the second attenuation coefficient after the transition is completed as the new first attenuation coefficient, and the reset new attenuation coefficient as the new second attenuation coefficient. Such ignoring of the input of the new attenuation coefficient during the transition period is performed by the delay circuit 5 to which the transition period is input.
1 is realized.

With the above operation, the coefficient interpolator 1 shown in FIG. 8 is used to change the transition characteristics and the transition period during the transition period.
Multiplication factor of _{3 k 0, k 1, ···} , multiplication coefficient of the coefficient interpolation section 13 shown in k _n and FIG 9 k, even if it is changed (1-k), change transition characteristic Also, the change of the transition period is delayed, and the occurrence of noise can be effectively prevented.
Such an operation is effective as another operation method in a case where noise may occur due to a change in the transition characteristic or the transition period in the operation illustrated in FIG.

Modified example. The configuration and operation of the electronic volume switching device according to the present invention have been described above. However, the present invention is not limited to the above embodiment, and various modifications are possible.

For example, in the above embodiment, the coefficient interpolation unit 1
3, a digital LP filter is used, but another configuration may be used. Further, the electronic volume switching device does not need to be configured as a dedicated electric circuit, and a part or the whole thereof may be constructed by software, and a general-purpose computer system may be used as the electronic volume switching device.

The operation flow of the electronic volume switching device in the above embodiment can be arbitrarily changed within substantially the same range. For example, in the above embodiment, 1
Although it has been described that one output attenuation coefficient is obtained by one interpolation process, a plurality of output attenuation coefficients may be obtained at one time. In this case, the determined plurality of output attenuation coefficients are sequentially provided to the attenuator 22 in accordance with the output timing. Even in such an operation, FIG.
The operation similar to the operation shown in FIG.

[0085]

According to the first aspect of the present invention, it is possible to reduce the occurrence of noise that occurs when the volume is switched.

According to the second aspect of the present invention, it is possible to set the time required for switching the volume.

According to the third aspect of the present invention, it is possible to suppress the occurrence of noise when the volume is further switched during the volume switching.

According to the fourth aspect of the invention, it is possible to suppress the occurrence of noise when the volume is further switched during the volume switching.

According to the fifth aspect of the present invention, reduction of noise generated at the time of volume switching is easily realized by using a digital LP filter.

According to the invention described in claim 6, noise generated when the volume is switched can be reduced.

According to the seventh aspect of the present invention, it is possible to set the time required for switching the volume.

According to the eighth aspect of the invention, it is possible to suppress the occurrence of noise when the volume is further switched during the volume switching.

According to the ninth aspect of the present invention, it is possible to suppress the occurrence of noise when the volume is further switched while the volume is being switched.

According to the tenth aspect of the present invention, reduction of noise generated at the time of volume switching is easily realized by using a digital LP filter.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of the configuration of an electronic volume switching device according to the present invention.

FIG. 2 is a flowchart showing an example of an operation flow of the electronic volume switching device.

FIG. 3 is a graph illustrating an example of a waveform of an output audio signal when interpolation of an attenuation coefficient is not performed.

FIG. 4 is a graph showing an example of a waveform of an output audio signal when interpolation of an attenuation coefficient is performed.

FIG. 5 is a block diagram illustrating an example of a configuration of a coefficient interpolation unit.

FIG. 6 is a flowchart showing another example of the operation flow of the electronic volume switching device.

FIG. 7 is a block diagram illustrating another example of the configuration of the coefficient interpolation unit.

FIG. 8 is a block diagram illustrating an example of a configuration of a coefficient interpolation unit that can change a transition period.

FIG. 9 is a block diagram showing another example of the configuration of the coefficient interpolation unit capable of changing the transition period.

FIG. 10 is a flowchart showing an example of an operation flow of the electronic volume switching device when a transition period is set at the time of volume switching.

FIG. 11 is a block diagram showing another example of the configuration of the electronic volume switching device according to the present invention.

FIG. 12 is a flowchart showing yet another example of the operation flow of the electronic volume switching device.

FIG. 13 is a block diagram showing a configuration of a conventional electronic volume switching device.

FIG. 14 is a graph showing an example of an output audio signal.

FIG. 15 is a graph showing an example of an output audio signal when a volume is switched by a conventional electronic volume switching device.

[Explanation of symbols]

1 electronic volume switching device, 13 coefficient interpolation unit, 22
Attenuator, 31a, 35 Delayer, 32a, 34, 36
Multipliers, 33 and 37 adders, 41 transition period changing unit, 51 a delay circuit, A ₀ to A _m damping coefficient, S11～S
13, S21 to S25, S41 to S45 Step.

Claims (10)

[Claims] 1. An electronic volume switching method for electrically switching a volume that changes according to an attenuation coefficient, comprising: (a) performing interpolation between a first attenuation coefficient before switching and a second attenuation coefficient after switching; Obtaining an output attenuation coefficient; (b) outputting an output audio signal by applying the output attenuation coefficient to an input audio signal in accordance with output timing; (c) the steps (a) and (b) Gradually changing the output attenuation coefficient from the first attenuation coefficient to the second attenuation coefficient so as to gradually switch the volume of the output audio signal. . 2. The electronic volume switching method according to claim 1, wherein: (d) the output damping coefficient is changed from the first damping coefficient to the second damping coefficient.
Setting a transition period for transitioning to an attenuation coefficient. 3. The electronic volume switching method according to claim 1, wherein (e) the latest output attenuation when a target attenuation coefficient is further switched during the execution of the step (c). Performing the step (c) using the coefficient as a new first attenuation coefficient and the target attenuation coefficient after switching as a new second attenuation coefficient. 4. The electronic volume switching method according to claim 1, wherein (f) the step (c) is performed when a target damping coefficient is further switched during the execution of the step (c). ) Is completed, the second damping coefficient is set as a new first damping coefficient, and the target damping coefficient after switching is set as a new second damping coefficient, and the step (c) is performed. Characteristic electronic volume switching method. 5. The electronic volume switching method according to claim 1, wherein in said step (a), said second attenuation coefficient is applied to a digital LP filter to which said first attenuation coefficient has been input. , And using the output from the digital LP filter as the output attenuation coefficient. 6. An electronic volume switching device for electrically switching a volume that changes according to a damping coefficient, wherein the electronic volume switching device interpolates between a first damping coefficient before switching and a second damping coefficient after switching, and Interpolating means for sequentially obtaining an output attenuation coefficient that gradually transitions from an attenuation coefficient to the second attenuation coefficient; and output means for outputting an output audio signal by sequentially applying the output attenuation coefficient to an input audio signal in accordance with output timing. An electronic volume switching device, comprising: 7. The electronic volume switching device according to claim 6, further comprising: means for setting a transition period in which the output attenuation coefficient transitions from the first attenuation coefficient to the second attenuation coefficient. An electronic volume switching device characterized by the above-mentioned. 8. The electronic volume switching device according to claim 6, wherein the interpolation unit is further switched when a target attenuation coefficient is further switched while the interpolation unit sequentially obtains the output attenuation coefficient. Sets the latest output attenuation coefficient as a new first attenuation coefficient, and sets the target attenuation coefficient after switching as a new second attenuation coefficient.
An electronic volume switching device for performing interpolation as a damping coefficient. 9. The electronic volume switching device according to claim 6, wherein the output attenuation is changed when a target attenuation coefficient is further switched while the interpolation means sequentially obtains the output attenuation coefficient. An electronic volume switching device, further comprising: means for stopping input of the target attenuation coefficient after switching to the interpolation means until the coefficient substantially becomes the second attenuation coefficient. 10. The electronic volume switching device according to claim 6, wherein the interpolation means has a digital LP filter.