JP2008245079A - Fade processor and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate various fade-out waveforms and/or fade-in waveforms, without having to use a cascade connection or a parallel connection of arithmetic units. <P>SOLUTION: A fade processor sets an updating expression C+(Flg-C)*T of a multiplication coefficient, where flag Flg is set to 0 or 1 for fade-out processing or fade-in processing, respectively. The initial value of the multiplication coefficient C is 1 or 0 for the fade-out processing or fade-in processing, respectively. A multiplication coefficient 14 updates the multiplication coefficient C, based on the update expression by each one-sampling time during a fade period and supplies the C to a multiplier 12. The multiplier 12 outputs, as a fade signal, a signal generated by multiplying the input audio signal by C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fade processing apparatus and method for fading out or fading an audio signal or the like.

  Patent Document 1 discloses a fade processing apparatus of a table reference method and an increment / decrement method in paragraphs 0002 and 0003 thereof.

  In the table reference type fade processing device, there is a problem that a table of a large number of coefficients is required and the required storage amount is increased. In addition, the increment / decrement type fade processing apparatus has a problem that the fade waveform becomes linear and does not match the hearing (paragraph 0003 of Patent Document 1).

Therefore, in the fade processing apparatus newly disclosed in Patent Document 1, first and second multipliers, an adder, and a delay circuit are provided, and the first and second multiplication coefficients are C1 and C2 (where C1 + C2 = 1, respectively). The gain data is input to the first multiplier, the adder adds the inputs from the first and second multipliers, and the delay unit delays the output of the adder by one sampling time. It outputs to a 2nd multiplier (FIG. 1 of patent document 1). Then, the output of the adder is sent to another multiplier (reference numeral 30 in FIG. 1 of Patent Document 1), multiplied by the audio signal in the other multiplier, and the audio signal is faded.
JP-A-4-345311

  In the fade processing apparatus of Patent Document 1, when various fade-out waveforms and fade-in waveforms are generated, the digital volume (reference numeral 16 in FIG. 1 of Patent Document 1) is manually operated or a plurality of arithmetic units are cascaded. Connection (FIG. 5 of Patent Document 1) or parallel connection (FIG. 7 of Patent Document 1) can only be made, and the operation becomes complicated and the configuration becomes complicated.

  An object of the present invention is to provide a fade processing apparatus and method capable of generating various fade-out waveforms and / or fade-in waveforms with a simple structure.

  According to the present invention, in a fade processing unit that generates a signal related to the product of the signal to be faded and the multiplication coefficient C as a fade signal, the fade speed coefficient T is introduced into the update formula of C, and the speed coefficient T Adjust the fade waveform by changing. The speed coefficient T is typically set prior to the start of fade (“fade” is “fade out” and / or “fade in”), but can be changed during the fade period. Can be.

The fade processing apparatus of the present invention includes the following.
An initial value setting means for setting an initial value of the multiplication coefficient C in the fade process;
A fade speed setting means for setting a fade speed coefficient T;
Update formula setting means for setting C update formulas: P · C and Q · C + R with P, Q, R as a function of T while defining in the range of 0 <P, Q, R <1;
In response to the sampling time, the multiplication coefficient updating means for updating the multiplication coefficient C based on the update formula: P · C in the fade-out period and the update formula: Q · C + R in the fade-in period; A fade signal generating means for generating a signal related to the product of the signal of No. 1 and the multiplication coefficient C as a fade signal.

The fade processing method of the present invention includes the following steps.
Setting an initial value of the multiplication coefficient C in the fade process;
A fade step for setting a fade speed coefficient T;
A step of setting C update formulas: P · C and Q · C + R with P, Q, R as a function of T while defining in a range of 0 <P, Q, R <1;
In response to the sampling time, in the fade-out period, based on the update formula: P · C, and in the fade-in period, based on the update formula: Q · C + R, the step of updating the multiplication coefficient C, and the signal to be faded Generating a signal related to the product of the multiplication coefficient C as a fade signal;

  According to the present invention, it is possible to generate various fade signals by introducing the fade speed coefficient T into the update formula of the multiplication coefficient C.

  FIG. 1 is a configuration diagram of a DSP (Digital Signal Processor) 10. The DSP 10 functions as an equivalent circuit of the analog / digital converter 11, the multiplier 12, the digital / analog converter 13, and the multiplication coefficient calculator 14. An analog audio signal is supplied as an input (IN) of the DSP 10.

  The analog audio signal is supplied to the analog / digital converter 11, converted into a digital signal, and then supplied to the multiplier 12. The multiplier 12 multiplies the digital signal from the analog / digital converter 11 by the multiplication coefficient C from the multiplication coefficient calculator 14 and outputs the result to the digital / analog converter 13. The digital / analog converter 13 converts the digital signal back to an analog signal and outputs it as an output of the DSP 10. Conversion in the analog / digital converter 11 and the digital / analog converter 13 is performed every sampling time.

  The DSP 10 is notified of the initial value of the multiplication coefficient C, the flag Flg, and the fade speed coefficient T as an I / O signal from an external CPU (not shown) or the like. Flg determines whether the fade processing in the DSP 10 is fade-out or fade-in. When Flg = 0, the fade processing is fade-out processing, and when Flg = 1, the fade processing is fade-in processing. Become. T is 0 <T <1. The initial value of C is not limited, but is generally set to 1 during the fade-out process, and is set to 0 during the fade-in process. In this case, the fade signal level is prevented from becoming discontinuous at the start of the fade.

  The initial value of the multiplication coefficient C, the flag Flg, and the fade speed coefficient T can be changed as appropriate. Prior to the start of the fading process of the DSP 10, the multiplication coefficient calculator 14 is notified of the initial value of C, and updates C with the following calculation formula (1) based on the initial value. When the multiplication coefficient C input to the multiplier 12 is 0, the output of the multiplier 12 is 0, that is, mute. When the multiplication coefficient C input to the multiplier 12 is 1, the output of the multiplier 12 is equal to the input of the multiplier 12, that is, the multiplier 12 is through.

  FIG. 2 is a flowchart of the fade processing method 20 executed in the DSP 10. The fade processing method 20 is executed every one sampling time based on the sampling time signal.

  In S21, the updated multiplication coefficient C is calculated from the multiplication coefficient C before update according to the following calculation formula (1). As described above, Flg takes either 0 or 1. When Flg = 0, the following equation (2) is obtained by arranging the equation (1) with respect to C. When Flg = 1, the following equation (3) is obtained by arranging the equation (1) with respect to C. It is a formula. In formulas (1) to (3), C on the left side is the one after the update, and C on the right side is the one before the update.

(1): C = C + (Flg−C) · T
(2): C = (1-T) · C
(3): C = (1-T) · C + T

  In the equations (1) to (3), 0 ≦ C ≦ 1, 0 <T <1. In S22, the multiplier 12 is caused to calculate the output OUT of the DSP 10 based on the following calculation formula (4). In the calculation formula (4), IN is an input of the DSP 10.

(4): OUT = IN · C

  Since 1−T <1, when C is repeatedly updated by the expression (2), C converges to 0 with respect to an arbitrary initial value. Further, when C is set to its initial value 0 and is repeatedly updated by the equation (3), C converges to 1.

  FIG. 3 shows the waveform of each part of the DSP 10 during the fading process. (A)-(c) is a waveform of a fade-in period, (d)-(f) is a waveform of a fade-out period. 3 and 4, Flg = 1 is set to C and the initial value of C = 0 in the fade-in process, and Flg = 0 is set to 0 and the initial value of C is set to 1 in the fade-out process.

  3, (a), (d) are the changes GA and GB of the multiplication coefficient C as the output of the multiplication coefficient calculator 14, (b), (e) are the input (IN) waveforms of the DSP 10, (c), (F) shows the output (OUT) waveform of the DSP 10. The input waveform is a simple sine wave. GA and GB are changes in C in the fade-in period and the fade-out period, respectively. When the multipliers 12 multiply the GA, GB and the input waveform of the DSP 10, the output waveforms of the DSP 10 as the multiplication results are (c), (F).

FIG. 4 shows waveforms at various parts of the DSP 10 when fade processing is performed with different fade speed coefficients T. (A)-(e) is a waveform of a fade-in period, (f)-(j) is a waveform of a fade-out period. (A), (f) shows the change GC, GD, GE, GF, GG, GH of the multiplication coefficient C as the output of the multiplication coefficient calculator 14. In the fade-in period, as can be seen from the calculation formula (3), the increase rate of C increases as T decreases. Therefore, T decreases in the order of GC, GD, and GE. That is, GC T> GD T> GE T. In the fade-out period, as can be seen from the calculation formula (3), the decrease rate of C increases as T increases.
Therefore, in (f), T increases in the order of GF, GG, and GH. That is, GF T <GG T <GH T.

  In FIG. 4, (b) and (g) show the input (IN) waveforms of the DSP 10. The input waveform is a simple sine wave. (C) to (e) are output (OUT) waveforms of the DSP 10 for GC, GD, and GE, respectively. Further, (h) to (j) are output (OUT) waveforms of the DSP 10 for GF, GG, and GH, respectively. In this way, by changing the fade speed coefficient T, various fade-in characteristics and fade-out characteristics can be obtained.

  3 and 4, the fade speed coefficient T is determined prior to the start of the fade, and is not changed during the fade period. FIG. 5 shows waveforms at various parts of the DSP 10 when the fade speed coefficient T is changed during the fade-out period. 5, (a), (b), and (c) show the change GI of the multiplication coefficient C, the input (IN) waveform of the DSP 10, and the output (OUT) waveform of the DSP 10, respectively.

  In FIG. 5, the multiplication coefficient C is set to 1 at time t0. Further, the flag Flg is maintained at 0 between times t0 and t3. The fade speed coefficient T is switched at times t1 and t2, and as a result, a bending point is generated in the GI at times t1 and t2. In the case of FIG. 5, there is a relationship of T <t2-t3 T <t1-t2 T <t2-t3 T <t2-t3 T <t2-t3. Note that the multiplication coefficient C takes over the previous value without discontinuity at the times t1 and t2.

  FIG. 6 shows waveforms at various parts of the DSP 10 when the flag Flg is switched during the fade period. 6, (a), (b), and (c) show the change GJ of the multiplication coefficient C, the input (IN) waveform of the DSP 10, and the output (OUT) waveform of the DSP 10, respectively.

  In FIG. 6, the multiplication coefficient C is set to 1 at time t0. The flag Flg is 0 between times t0 and t1, and is 1 between times t1 and t2. The multiplication coefficient C takes over the previous value regardless of the switching of the flag Flg at time t1. GJ rises from time t1 before C = 0.

  FIG. 7 shows waveforms of respective parts of the DSP 10 when the flag Flg and the fade speed coefficient T are appropriately switched during the fade period. In FIG. 7, (a), (b), and (c) are the change GK of the multiplication coefficient C, the input (IN) waveform of the DSP 10, and the output (OUT) waveform of the DSP 10, respectively.

  In FIG. 7, the fade speed coefficient C is set to 1 at time t <b> 0, and thereafter continues regardless of the switching of the flag Flg or the fade speed coefficient T. In the rising period of the multiplication coefficient, the flag Flg = 1, and in the falling period of the multiplication coefficient, the flag Flg = 0. The fade speed coefficients T in the periods t0-t1, t1-t2, t2-t3, t3-t4, t4-t5, t5-t6 are different from each other. As a result, the change rate of GK is different in each period.

  FIG. 8 is a block diagram of the fade processing apparatus 30. The DSP 10 described above is a specific example of the fade processing device 30. The fade processing device 30 basically includes an initial value setting means 31, a fade speed setting means 32, an update equation setting means 33, a multiplication coefficient updating means 34, and a fade signal generating means 35, and additionally, a flag setting means. 39.

  The initial value setting means 31 sets an initial value of the multiplication coefficient C in the fade process. The fade speed setting means 32 sets a fade speed coefficient T. The update formula setting means 33 sets C update formulas: P · C and Q · C + R with P, Q, and R as functions of T while defining in the range of 0 <P, Q, R <1.

  In response to the sampling time, the multiplication coefficient updating unit 34 updates the multiplication coefficient C based on the update formula: P · C in the fade-out period and based on the update formula: Q · C + R in the fade-in period. The fade signal generation unit 35 generates a signal related to the product of the signal to be faded and the multiplication coefficient C as a fade signal. Note that P corresponds to the coefficient part (1-T) in the above-described calculation formula (2). Q and R correspond to the coefficient parts (1-T) and T in the above-described calculation formula (3), respectively.

  The fade processing device 30 performs both the fade-out process and the fade-in process, but may be configured to perform only one of the fade-out process and the fade-in process. In that case, the fade speed setting means 32 becomes a fade-out speed setting means or a fade-in speed setting means. The fade signal generation means 35 is a fade-out signal generation means or a fade-in signal generation means.

  “According to sampling time” is, for example, “every sampling time”, but is not limited thereto. Assume that the multiplication coefficient C may be updated every two sampling times or every three sampling times. A flag setting unit 39 may be added to the fade processing device 30. The flag setting means 39 sets the flags Flg to 0 and 1 respectively in the fade-out process and the fade-in process. On the other hand, the update formula setting means 33 uses P, Q, and R as functions of the fade speed coefficient T and the flag Flg.

  Preferably, the update formula setting means 33 derives the C update formulas: P · C and Q · C + R from C + (Flg−C) · T. Preferably, the flag setting means 39 can switch the flag Flg during the fade period.

  The initial value setting unit 31 sets the initial value of the multiplication coefficient C to 1 or 0 in the fade-out process and the fade-in process, respectively. When the initial value of C is set to 0 and the flag Flg is set to 1, if C is repeatedly updated a sufficient number of times using C + (Flg−C) · T, C converges to 1. Preferably, the fade speed setting means 32 is capable of changing the fade speed coefficient T during the fade period.

  FIG. 9 is a flowchart of the fade processing method 46. In S47, an initial value of the multiplication coefficient C in the fade process is set. In S48, a fade speed coefficient T is set. In S49, while defining in the range of 0 <P, Q, R <1, C update formulas: P · C and Q · C + R are set with P, Q, R as a function of T.

  In S50, in response to the sampling time, the multiplication coefficient C is updated based on the update formula: P · C in the fade-out period, and based on the update formula: Q · C + R in the fade-in period. In S51, a signal related to the product of the signal to be faded and the multiplication coefficient C is generated as a fade signal.

  Fade processing method 20 (FIG. 2) is an example of fade processing method 46. The order of S47 and S48 can be reversed. The processes of S47 to S51 correspond to the functions of the initial value setting unit 31 to the fade signal generation unit 35 of the fade processing device 30 (FIG. 8), respectively.

  The specific mode described for the functions of the initial value setting unit 31 to the fade signal generation unit 35 can be applied as a specific mode for the processing of S47 to S51. In the fade processing method 46, a step of executing a process corresponding to the function of the flag setting unit 39 of the fade processing device 30 can be added as appropriate. The steps corresponding to the flag setting means 39 can be arranged anywhere before S49 in the fade processing method 46 of FIG. The specific mode of the functions of the initial value setting unit 31 to the fade signal generation unit 35 described for the addition of the flag setting unit 39 is the specific mode of the processing of S47 to S51 for the addition of the step corresponding to the flag setting unit 39. As applied.

  This specification includes various inventions. The invention disclosed in this specification is based on various forms described as the best mode of the invention, etc., in which only some elements are combined, some of the elements are changed within obvious ranges, and obvious among various forms. Including those that replace some components in the scope.

It is a block diagram of DSP. It is a flowchart of the fade processing method performed in DSP. It is a figure which shows the waveform of each part of DSP at the time of a fade process. It is a figure which shows the waveform of each part of DSP at the time of performing a fade process with a different fade speed coefficient. It is a figure which shows the waveform of each part of DSP at the time of changing a fade speed coefficient during a fade-out period. It is a figure which shows the waveform of each part of DSP when a flag is switched during a fade period. It is a figure which shows the waveform of each part of DSP at the time of switching a flag and a fade speed coefficient suitably in a fade period. It is a block diagram of a fade processing apparatus. It is a flowchart of a fade processing method.

Explanation of symbols

30: Fade processing device, 31: Initial value setting means, 32: Fade speed setting means, 33: Update formula setting means, 34: Multiplication coefficient updating means, 35: Fade signal generating means, 39: Flag setting means, 46: Fade Processing method.

Claims (9)

An initial value setting means for setting an initial value of the multiplication coefficient C in the fade-out process;
A fade-out speed setting means for setting a fade-out speed coefficient T;
Update formula setting means for setting C: P · C with P as a function of T while defining a range of 0 <P <1;
In the fade-out period in response to the sampling time, the multiplication coefficient updating means for updating the multiplication coefficient C based on P · C is generated, and a signal related to the product of the signal to be faded out and the multiplication coefficient C is generated as a fade-out signal Fade-out signal generation means,
A fade processing apparatus comprising: An initial value setting means for setting an initial value of the multiplication coefficient C in the fade-in process;
A fade-in speed setting means for setting a fade-in speed coefficient T;
Update formula setting means for setting the update formula of C: Q · C + R with Q and R as a function of T while defining in the range of 0 <Q and R <1;
In the fade-in period in response to the sampling time, the multiplication coefficient updating means for updating the multiplication coefficient C based on the update formula: Q · C + R, and the signal relating to the product of the signal to be faded in and the multiplication coefficient C are faded Fade-in signal generation means for generating as
A fade processing apparatus comprising: An initial value setting means for setting an initial value of the multiplication coefficient C in the fade process;
A fade speed setting means for setting a fade speed coefficient T;
Update formula setting means for setting C: P · C and Q · C + R with P, Q, R as a function of T while defining in the range of 0 <P, Q, R <1;
In response to the sampling time, the multiplication coefficient updating means for updating the multiplication coefficient C based on the update formula: P · C in the fade-out period and the update formula: Q · C + R in the fade-in period; A fade signal generating means for generating a signal related to the product of the signal of No. 1 and the multiplication coefficient C as a fade signal;
A fade processing apparatus comprising: In the fade-out process and the fade-in process, flag setting means for setting the flags Flg to 0 and 1, respectively, and the update formula setting means for using P, Q, and R as a function of the fade speed coefficient T and the flag Flg,
The fade processing apparatus according to claim 3, further comprising:   5. The fade processing apparatus according to claim 4, wherein the update formula setting means derives C update formulas: P · C and Q · C + R from C + (Flg−C) · T.   6. A fade processing apparatus according to claim 4, wherein the flag setting means is capable of switching the flag Flg during a fade period.   7. The fade processing apparatus according to claim 1, wherein the initial value setting means sets the initial value of the multiplication coefficient C to 1 or 0 in the fade-out process and the fade-in process, respectively.   8. A fade processing apparatus according to claim 1, wherein the fade speed setting means is capable of changing a fade speed coefficient T during a fade period. Setting an initial value of the multiplication coefficient C in the fade process;
A fade step for setting a fade speed coefficient T;
A step of setting C update formulas: P · C and Q · C + R with P, Q, R as a function of T while defining in a range of 0 <P, Q, R <1;
In response to the sampling time, the step of updating the multiplication coefficient C based on the update formula of C / C in the fade-out period and the update formula: Q / C + R in the fade-in period, and the fade processing target Generating a signal related to the product of the signal and the multiplication coefficient C as a fade signal;
A fade processing method comprising:

Images