JP2016061909A - Distortion device, distortion control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce clipping nose with respect to a distortion device, a distortion control method, and a program that impart distortion effect to an input sound signal.SOLUTION: A clipper 318 clips an input sound signal. A clipper input level detection part 304 detects a clipper input level signal 306 as an envelope crest value of the input sound signal which is clipped. When the clipper input level signal 306 enters a predetermined offensive range, an adder 320 mixes a signal, obtained by gradually increasing the level of the input sound signal by a clean gain multiplier 319, with the output of the clipper 318 gradually decreased in output level by a clipper gain multiplier 317 and outputs the resulting signal as an output sound signal. When the clipper input level signal 306 exits from the predetermined offensive range, the adder 320 mixes a signal, obtained by gradually decreasing the level of the input sound signal by the clean gain multiplier 319, with the output of the clipper 318 gradually increased in output level by the clipper gain multiplier 317 and outputs the resulting signal as an output sound signal.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a distortion apparatus, a method, and a program for giving a distortion effect to an input sound signal.

  2. Description of the Related Art Distortion devices that obtain a distortion effect by so-called clipping that restricts the amplitude of a sound signal after amplifying an input sound signal such as a musical sound signal are well known. A big problem with this distortion effect is clipping noise when the distortion effect disappears, especially when playing chords.

  FIG. 10 is a diagram illustrating an example of a time domain waveform of clipping noise. In the synthesized signal at the time of playing a chord, a place with a high peak value is generated in a long cycle of several Hz (hertz) or several tens of Hz due to the undulation of each constituent sound. When this signal is distorted as an input signal, for example, as shown in FIG. 10 (a), when the amplitude level of the input sound signal is high, the density of clipping is high, so each clip waveform component Cannot be heard without being masked. On the other hand, for example, as shown in FIG. 10B, in the process in which the amplitude level of the input sound signal is lowered, the final display is shown in FIG. 10B (represented by 1001 in the figure). Only the part (clip point) with a high peak value due to the superposition of each component sound indicated by a circle is clipped. In this case, since the density at which clipping occurs is low and irregular, each clip waveform component can be heard.

  FIG. 11 is a diagram illustrating an example of a frequency band waveform of clipping noise. In the frequency range, during the period when sufficient distortion is applied, the harmonic spectrum component 1101 of clipping noise is generated at a steady level without depending on the level of the input signal, as shown in FIG. Yes. Here, when the amplitude level of the input sound signal is high, the harmonic spectrum component 1101 is masked by the spectrum component of the input sound signal and cannot be heard. However, when the amplitude level of the input sound signal falls below a certain threshold, clipping noise due to the harmonic spectrum component 1101 can be heard. Then, at the moment when the amplitude level of the input sound signal is further lowered and clipping is eliminated, this noise has a discontinuous characteristic that the noise is not generated at all.

  Moreover, because the clipping noise generation interval is long enough to be heard by the human ear, changes in the generation density of clips when the distortion effect disappears can be easily recognized as “Gee”, “Chile Chile”, “Titchic…” This low density and discontinuous operation feels very uncomfortable. Particularly, in the distortion by digital processing, there is no continuous element that alleviates the phenomenon, and there is a tendency that an element having an unpleasant feeling is output as it is.

  Conventionally, various techniques for controlling the distortion waveform and controlling the sound quality of the distortion sound effect are known (the techniques described in Patent Documents 1 to 4).

JP 2001-154675 A JP 2001-184669 A JP 2005-250357 A Japanese Patent No. 3149559

  However, a technique that can reduce clipping noise has not been known.

  Therefore, an object of the present invention is to reduce clipping noise.

  In an example of the aspect, when the level of the input signal becomes equal to or higher than a predetermined clip level, a clipper unit that clips and outputs the input signal, and an output signal from the clipper unit and the input signal are mixed. When the mixing unit for outputting, the envelope level detecting unit for detecting the envelope level value of the input signal, and the envelope level detected by the envelope level detecting unit are within a predetermined region including the clipping level, from the clipper unit And a control unit that controls to increase the level of the input signal supplied to the mixing unit.

  According to the present invention, clipping noise can be reduced.

It is an external view of the distortion apparatus which concerns on this embodiment. It is a figure which shows the hardware structural example of the distortion apparatus which concerns on this embodiment. It is a figure which shows the block structural example of DSP. It is explanatory drawing of a register. It is operation | movement explanatory drawing (the 1) of this embodiment. It is operation | movement explanatory drawing (the 2) of this embodiment. It is a flowchart which shows the example of the whole process of distortion control. It is a flowchart which shows the example of an Effect / Bypass reading setting process. It is a flowchart which shows the example of a clipper level adjustment process. It is a figure explaining the example of the time domain waveform of clipping noise. It is a figure explaining the example of the frequency domain waveform of clipping noise.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the present embodiment, a compact effector that executes signal processing using a DSP (Digital Signal Processor) will be described as an example.

  FIG. 1 is an external view of a distortion device 100 according to the present embodiment. The main body of the distortion device 100 includes, for example, an input terminal (Input) 101 that inputs an input sound signal that is a musical sound signal, and an output terminal (Output) 102 that outputs an output sound signal to which a distortion effect is added. In addition, the distortion device 100 includes an effect bypass indicator 103 that displays whether or not the distortion effect is applied. In addition, the distortion device 100 includes a drive control knob (Drive Control) 104 that controls the degree of the distortion effect, a tone control knob (Tone Control) 105 that controls the sound quality of the distortion effect, and a level control that controls the output level of the output sound signal. A knob (Level Control) 106 is provided. Further, a pedal switch 107 is provided for controlling on / off of the distortion effect when the user steps on the foot.

  FIG. 2 is a diagram illustrating a hardware configuration example of the distortion device 100 in FIG. 1. The distortion device 100 includes a CPU 201, a ROM 202, a RAM 203, a DSP 204, an amplifier 205, an A / D (analog / digital) converter 206, a work memory 207, a D / A (digital / analog) converter 208, and an amplifier 209. Further, the distortion device 100 includes an LED (Light Emitting Diode) 214 and a parallel port 206 that controls the LED 214, a pedal switch 210 and a flip-flop digital circuit 211 that controls the pedal switch 210, and a control knob 212 and an A / A D converter 213 is provided. The CPU 201, ROM 202, RAM 203, parallel port 206, flip-flop digital circuit 211, and A / D converter 213 are connected to each other by a system bus 214. The LED 214 corresponds to the effect bypass indicator 103 of FIG. The control knob 212 corresponds to the control knob group 104, 105, 106 in FIG. The pedal switch 210 corresponds to the pedal switch 107 in FIG.

  The analog input sound signal input from the input terminal 215 is amplified by the amplifier 205 and then the digital input sound signal (hereinafter simply referred to as “input sound signal”) by the A / D converter 206. Is input to the DSP 204.

  The DSP 204 executes audio processing for adding a distortion effect to the input sound signal and clipper input level detection processing described later, while using the work memory 207 as a work amount area in accordance with control from the CPU 201. A digital output sound signal (hereinafter simply referred to as “output sound signal” means a digital output sound signal) is output.

  The output sound signal output from the DSP 204 is converted into an analog output sound signal by the D / A converter 208, amplified by the up 209, and then output from the output terminal 102.

  The user interface such as reading the operation position of the control knob 212 via the A / D converter 213 and displaying it on the LED 214 via the parallel port 206 is processed by the CPU 201. The distortion effect (hereinafter referred to as “effect”) is switched on / off (effect / bypass) by the CPU 201 reading the toggle inversion result in the flip-flop digital circuit 211 based on the operation of the pedal switch 210 and instructing the DSP 204. It is done by giving. The CPU 201 gives various parameters described later to the DSP 204.

  The detection and adjustment of the clipping state in the distortion effect is realized by the CPU 201 reading and determining a detection result of a clipper input level (to be described later) in the DSP 204 and transmitting the determination result to the DSP 204.

  FIG. 3 is a diagram showing a block configuration example of the DSP 204 in FIG. The DSP 204 includes an effect / bypass switching unit 301, a CPU interface unit 302, an audio processing unit 303, and a clipper input level detection unit 304 as basic functional configurations.

  First, the CPU interface unit 302 is a register group used for communication with the CPU 201, and the CPU 201 reads or writes to these register groups. The DSP 204 reads these register groups for each cycle of signal processing and executes processing.

  FIG. 4 is an explanatory diagram of a register group of the CPU interface unit 302.

  The effect bypass register EFFECT is an input register having a bit width of 1 bit, which holds an effect / bypass signal 305 for controlling the effect switching from the CPU 201. The effect / bypass signal 305 can take a 1-bit value “0” (Bypass: invalid) or “1” (Effect: valid).

  The clipper input level register CINPUT is an output register having a bit width of 16 bits, which holds a clipper input level signal 306 that is output to the CPU 201 and represents the level of the input envelope as an absolute value. The clipper input level signal 306 can take a 16-bit value “0” to “FFFF”. If this value exceeds 1000, clipping is performed.

  The clipper gain register CGAIN is an input register having a bit width of 16 bits, which holds a clipper gain signal 307 that is input from the CPU 201 and sets a multiplier of a clipper gain multiplier. The clipper gain signal 307 can take a 16-bit value from “0” to “8000”. When this value is “8000”, the gain is 1.0 times.

  The clean gain register LGAIN is an input register having a bit width of 16 bits, which holds a clean gain signal 308 that is input from the CPU 201 and sets a multiplier of a multiplier for clean gain. Similarly to the clipper gain signal 307, the clean gain signal 308 can take a value of 16 bits from “0” to “8000”. When this value is “8000”, the gain is 1.0 times.

  The drive register DRIVE is an input register having a bit width of 8 bits, which holds a drive signal 309 that is input from the CPU 201 and sets an amplification factor of drive amplification. The drive signal 309 can take an 8-bit value “0” to “FF”. When this value is “FF”, the amplification factor is maximized.

  The tone register TONE is an input register having a bit width of 8 bits that holds a tone signal 310 for setting a timbre input from the CPU 201. The tone signal 310 can take an 8-bit value from “0” to “FF”. The higher this value is, the higher the cutoff frequency (cut-off frequency) becomes. When this value is “FF”, the cut-off frequency becomes maximum.

  The level register LEVEL is an input register having a bit width of 8 bits that holds a level signal 311 that is input from the CPU 201 and sets the amplification factor of the final stage amplifier. The level signal 311 can take an 8-bit value “0” to “FF”. When this value is “FF”, the amplification factor is maximized.

  Returning to the description of FIG. 3, the effect / bypass switching unit 301 will be described. Whether the effect is enabled or not is switched by the CPU 201 setting the effect / bypass signal 305 in the effect bypass register EFFECT. As described above, when the value “0” is set as the effect / bypass signal 305, the effect / bypass switching unit 301 connects the input terminal 312 to the bypass line 313. As a result, the input sound signal input from the input terminal 312 is directly output from the output terminal 314 via the bypass line 313, and the effect is invalidated. When the value “1” is set as the effect / bypass signal 305, the effect / bypass switching unit 301 connects the input terminal 312 to the audio processing unit 303 and the clipper input level detection unit 304. As a result, the effect on the input sound signal input from the input terminal 312 is validated.

  The CPU 201 alternates the value of the effect / bypass signal 305 between “0” and “1” based on the toggle inversion signal input via the flip-flop digital circuit 211 every time the user steps on the pedal switch 210. Switch to. In this way, the user can switch the effect between valid and invalid each time the pedal switch 210 is depressed.

  When the value “1” is set as the effect / bypass signal 305, the CPU 201 turns on the LED 214 through the parallel port 206 to indicate that the effect is valid, and conversely, the value “0” as the effect / bypass signal 305. Is set, the LED 214 is turned off to indicate that the effect is invalid.

  Next, the audio processing unit 303 will be described. The audio processing unit 303 includes a high pass filter (HPF) 315, a drive multiplier 316, a clipper gain multiplier 317, a clipper 318, a clean gain multiplier 319, an adder 320, a tone adjustment low pass filter (LPF) 321, A level multiplier 322, a clipper gain smoothing LPF 323, and a clean gain smoothing LPF 324 are provided.

  First, the HPF 315 cuts an unnecessary low frequency component of the input sound signal input from the input terminal 312 via the effect / bypass switching unit 301.

  Next, amplification according to the depth of the distortion effect is performed. The present embodiment is in the control of this amplification operation. The multiplier for determining the amplification factor has a two-stage configuration of a drive multiplier 316 and a clipper gain multiplier 317, in which the drive setting is performed in the former and the clipper gain is adjusted in the latter. Here, when the user operates the control knob 212 (see FIG. 2) corresponding to the drive control knob 104 (see FIG. 1), the operation amount is notified to the CPU 201 via the A / D converter 213. The CPU 201 determines the value of the drive signal 309 based on this operation amount information. Although the control of the clipper gain signal 307 will be described later, the clipper gain signal 307 set from the CPU 201 to the clipper gain register CGAIN of the CPU 201 interface 1101 is input to the clipper gain smoothing LPF 323 in order to smooth the gain control. The output is input to the clipper gain multiplier 317. The above amplification control will be described later.

  Next, the output of the clipper gain multiplier 317 is input to the clipper 318. The clipper 318 has a function of distorting the waveform by clipping the waveform by limiting the peak value of the input sound signal. The crest value to be clipped is fixed, and the degree of clipping is determined by the amplification operation of the drive multiplier 316 and the clipper gain multiplier 317 in the previous stage. By increasing the amplification factor in the previous stage, clipping can be easily performed even with a small input sound signal.

  The output of the clipper 318 is added (mixed) in the adder 320 with the input sound signal (clean signal) output from the HPF 315 and gain-adjusted by the clean gain multiplier 319. As a result, the added output output from the adder 320 is subjected to sound quality adjustment by the tone adjusting LPF 321, then level-adjusted by the level multiplier 322, and output from the output terminal 314 as an output sound signal.

  The tone adjustment LPF 321 can adjust the cut-off frequency by the tone signal 310 set in the tone register TONE of the CPU interface unit 302 from the CPU 201, thereby adjusting the sound quality. Here, when the user operates the control knob 212 (see FIG. 2) corresponding to the tone control knob 105 (see FIG. 1), the operation amount is notified to the CPU 201 via the A / D converter 213. The CPU 201 determines the value of the tone signal 310 based on the operation amount information.

  The final stage gain in the level multiplier 322 can be adjusted by the level signal 311 set in the level register LEVEL of the CPU interface unit 302 from the CPU 201, so that the user can adjust the final volume level. Here, when the user operates a control knob 212 (see FIG. 2) corresponding to the level control knob 106 (see FIG. 1), the operation amount is notified to the CPU 201 via the A / D converter 213. The CPU 201 determines the value of the level signal 311 based on this operation amount information.

  Next, the clipper input level detection unit 304 will be described. The clipper input level detection unit 304 includes a rectifier 325, an LPF 326, and a multiplier 327, and has a function of detecting an input level to the clipper 318 in the audio processing unit 303. The rectifier 325 rectifies the input sound signal input from the input terminal 312 via the effect / bypass switching unit 301 when the effect is valid, and converts it into an absolute value. The LPF 326 obtains an envelope peak value by smoothing the absolute value output of the rectifier 325. The envelope peak value is amplified by the multiplier 327 whose gain is adjusted by the drive signal 309 with the same amplification factor as that of the drive multiplier 316 in the audio processing unit 303, and has a level corresponding to the level of the signal sent to the clipper 318. Converted to envelope peak value. The output of the multiplier 327 is stored in the clipper input level register CINPUT in the CPU interface unit 302 as the clipper input level signal 306 and sent to the CPU 201.

  A control process executed by the DSP 204 having the above configuration and the CPU 201 shown in FIG. 2 to suppress unpleasant distortion due to clipping noise when the effect is effective will be described in detail below. In this control process, the CPU 201 determines the clipper input level signal 306 notified from the clipper input level detection unit 304 in the DSP 204 via the clipper input level register CINPUT in the CPU interface unit 302, and the determination result is the DSP 204. This is realized by feedback to the control.

  5 and 6 are explanatory diagrams of the operation of this embodiment.

  First, in “clipper input level adjustment 1” in FIG. 5A, the CPU 201 periodically checks the envelope peak value of the clipper input level signal 306 output from the DSP 204, and the envelope peak value is within the uncomfortable region 501. Judge whether or not. When the CPU 201 determines that the envelope peak value has entered the uncomfortable region 501, the sound processing unit 303 in the DSP 204 receives the input sound signal to the clipper 318 while maintaining the input level corresponding to the input level of the envelope peak value. The clipper gain of the clipper gain multiplier 317 is adjusted by the clipper gain signal 307 so as not to be sent. As a result, control is performed so that the time during which the output sound signal stays in the uncomfortable region 501 is reduced as much as possible.

  Specifically, while the envelope peak value is within the range of the uncomfortable region 501, the gain in the clipper gain multiplier 317 is slightly reduced, so that the signal gain input to the clipper 318 corresponds to the uncomfortable region 501. The clipper gain signal 307 is adjusted so as to be equal to or less than the gain to be performed.

  Actually, the discomfort region 501 has a higher discomfort level as the envelope peak value is closer to the center level of the discomfort region 501. Therefore, when the level in the appropriate range from the center level, for example, the value of the center level is set to “1.0”, a range from “0.8” to “1.2” is set as the discomfort region 501. .

  As soon as the envelope peak value based on the clipper input level signal 306 enters the unpleasant area 501, the CPU 201 performs gain adjustment by the clipper gain signal 307, and the envelope peak value returns above the unpleasant area 501 or is uncomfortable. When any state falls below the area 501, the gain adjustment is immediately released. However, if the level change at this time is abrupt, an unnatural volume change occurs or another noise is generated by the control itself. Therefore, the clipper gain signal 307 set in the clipper gain register CGAIN in the CPU interface unit 302 from the CPU 201 is not input to the clipper gain multiplier 317 as it is, but is input via the clean gain smoothing LPF 324. The Thereby, the reaction by the gain adjustment is alleviated.

  Next, specific gain adjustment in the uncomfortable area 501 will be described with clipper input level adjustment 2 in FIG. If the envelope peak value is attenuated and enters the unpleasant area 501, the CPU 201 sets the lowest value of the unpleasant area 501 = “0.8” as the value of the clipper gain signal 307. Then, when the value of the clean gain signal 308 = “0.8” passes through the clean gain smoothing LPF 324, a clipper gain signal as indicated by a dotted line 503 in FIG. This is supplied to the multiplier 317.

  As a result, in the audio processing unit 303 in FIG. 3, the envelope of the signal sent from the clipper gain multiplier 317 to the clipper 318 is changed to a curve as indicated by 504 of clipper input level adjustment 3 in FIG. Is done. However, since the level difference at the boundary portion of the uncomfortable area 501 may generate noise if it remains as it is, correction is performed by adding an undistorted clean signal by the adder 320. As the clean signal, a signal output from the HPF 315 bypassing the clipper 318 is used. The operation of the clean gain multiplier 319 will be described later.

  Next, control of the clean gain signal 308 will be described. In the clipper input level adjustment 4 in FIG. 6A, when the envelope peak value based on the clipper input level signal 306 attenuates and enters the unpleasant area 501, the CPU 201 sets the minimum value of the unpleasant area 501 = “0.2. "Is set as the value of the clean gain signal 308. The clean gain signal 308 is set in the clean gain register LGAIN in the CPU interface unit 302 of FIG. The clean gain signal 308 passes through the clean gain smoothing LPF 324, whereby a clean gain signal as indicated by a dotted line 505 in FIG. 6A is supplied to the clean gain multiplier 319. .

  As a result, in the audio processing unit 303 in FIG. 3, the envelope of the clean signal sent from the clean gain multiplier 319 to the adder 320 is a curve as indicated by 506 in the clipper input level adjustment 5 in FIG. Changed to

  As a result, the output of the clipper 318 and the output of the clean gain multiplier 319 bypassing the clipper 318 are mixed by the adder 320 as indicated by the clipper input level adjustment 6 507 in FIG. As a result, almost smooth volume characteristics can be realized.

  As a result of the above control process, as shown in FIG. 5C, the time for the signal input to the clipper 318 to pass through the vicinity of the center of the uncomfortable region 501 is greatly shortened, so the time for feeling uncomfortable is also greatly reduced. It becomes possible to make it.

  Even if the level exceeds the uncomfortable region 501 on the way, a continuous and smooth clipper gain can be generated by the effect of the clipper gain smoothing LPF 323 in the same way, and the value of the signal input to the clipper 318 is uncomfortable. It is possible to move away from the region 501.

  If the input sound signal enters a level at which clipping does not occur, no adjustment is made, that is, the clipper gain returns to a state of 1.0 times, so the final sustain does not change.

  An example of the control process of the CPU 201 in FIG. 2 for realizing the above control operation will be described below. FIG. 7 is a flowchart showing an example of the overall processing of the distortion control. This process is a process in which the CPU 201 executes a distortion control processing program stored in the ROM 202 while using the RAM 203 as a work area.

  First, the CPU 201 initializes the stored contents of the RAM 203 (step S701).

  Next, the CPU 201 executes Effect / Bypass (effect / bypass) reading / setting processing (step S702). In this process, control corresponding to an operation in which the user steps on the pedal switch 210 in FIG. 2 (the pedal switch 107 in FIG. 1) is executed.

  FIG. 8 is a flowchart showing an example of the Effect / Bypass read setting process in step S702 of FIG.

  When the CPU 201 reads the Effect / Bypass toggle inversion state from the pedal switch 210 via the flip-flop digital circuit 211, the CPU 201 determines whether the state designates Effect (valid) or Bypass (invalid). Determination is made (step S801).

  If the Bypass (effect invalid) state is designated by the flip-flop digital circuit 211, the CPU 201 sets the value of the effect / bypass signal 305 to a value “0” indicating Bypass (step S802).

  On the other hand, if the Effect (effect effective) state is designated by the flip-flop digital circuit 211, the CPU 201 sets the value of the effect / bypass signal 305 to a value “1” indicating Effect (step S803).

  After the process in step S802 or S803, the effect / bypass read setting process in step S702 of FIG. 7 illustrated in the flowchart of FIG. 8 is terminated.

  Returning to the description of FIG. 7, the CPU 201 next executes a Drive / Tone / Level (drive / tone / level) reading / setting process (step S703). In this process, control corresponding to an operation in which the user turns the control knob 212 of FIG. 2 corresponding to the drive control knob 104, the tone control knob 105, or the level control knob 106 of FIG. Specifically, the CPU 201 reads the value of the position of the control knob 212 corresponding to the drive control knob 104 from the A / D converter 213, converts it to an 8-bit value between “0” and “FF”, and drives the drive signal. The value of 309 is set in the drive register DRIVE in the CPU interface unit 302 of FIG. Next, the CPU 201 reads the value of the position of the control knob 212 corresponding to the tone control knob 105 from the A / D converter 213, converts it to an 8-bit value between “0” and “FF”, and The value is set in the tone register TONE in the CPU interface unit 302 of FIG. Further, the CPU 201 reads the value of the position of the control knob 212 corresponding to the level control knob 106 from the A / D converter 213, converts it to an 8-bit value between “0” and “FF”, and the value of the level signal 311 And set in the level register LEVEL in the CPU interface unit 302 of FIG.

  After the processes in steps S702 and S703, the CPU 201 executes clipper level adjustment processing (step S704). In this process, control for setting the clipper gain signal 307 and the clean gain signal 308 is executed.

  Thereafter, the CPU 201 returns to the process of step S702 and repeats the control operation.

  FIG. 9 is a flowchart illustrating an example of the clipper level adjustment process in step S704 of FIG.

  The CPU 201 reads the value of the clipper input level signal 306 from the clipper input level register CINPUT in the CPU interface unit 302 of the DSP 204. As described above with reference to FIG. 4, the clipper gain signal 307 is set so that clipping is performed just when the value of the clipper input level signal 306 exceeds a hexadecimal value of 1000. In this embodiment, the clipping value is expressed as “1.0”. As described above, an uncomfortable area is determined at a level from “0.8” to “1.2” with reference to this.

  That is, the CPU 201 stores the value obtained by dividing the clipper input level signal 306 by the hexadecimal number 1000 in a variable l (alphabet L) on the RAM 203 (step S9091).

  Next, the CPU 201 determines whether or not the value of the variable l is larger than 1.2 (step S902).

  If the determination in step S902 is NO, the CPU 201 determines whether the value of the variable l is smaller than 0.8 (step S903).

  If the determination in step S903 is also NO, the CPU 201 determines that the envelope peak value based on the clipper input level signal 306 has entered the unpleasant region 501 described above. In this case, the CPU 201 immediately sets the value “0.8” in the clipper gain register CGAIN in the CPU interface unit 302 in the DSP 204 of FIG. 3 and the value “0.2” in the clean gain register LGAIN. Thus, when the clipper gain signal 307 output from the clipper gain register CGAIN is input to the clipper gain smoothing LPF 323, a clipper gain waveform curve corresponding to the first half of 503 in FIG. 5B is generated. Input to the gain multiplier 317. Further, when the clean gain signal 308 output from the clean gain register LGAIN is input to the clean gain smoothing LPF 324, a clean gain waveform curve corresponding to the first half of 505 in FIG. To the multiplier 319.

  If the determination in step S902 or step S903 is YES, the CPU 201 determines that the envelope peak value based on the clipper input level signal 306 has come out of the unpleasant region 501 described above. In this case, the CPU 201 immediately returns the value of the clipper gain register CGAIN in the CPU interface unit 302 in the DSP 204 of FIG. 3 to “1.0”, and similarly returns the value of the clean gain register LGAIN to “0.0”. . As a result, when the clipper gain signal 307 output from the clipper gain register CGAIN is input to the clipper gain smoothing LPF 323, a clipper gain waveform curve corresponding to the second half of 503 in FIG. Input to the gain multiplier 317. Further, when the clean gain signal 308 output from the clean gain register LGAIN is input to the clean gain smoothing LPF 324, a clean gain waveform curve corresponding to the second half of 505 in FIG. To the multiplier 319.

  As described above, in this embodiment, the clipper input level detection unit 304 detects the envelope peak value of the clipper input level of the input sound signal, and in the small level region when the distortion effect due to clipping disappears, the audio of FIG. By performing level control so that the signal subjected to the distortion effect output from the clipper 318 in the processing unit 303 and the clean signal output from the clean gain multiplier 319 are crossfade, discontinuous and low density It is possible to prevent the section where clipping noise is generated from being maintained at a constant spectral level.

  As a result, it is possible to realize an electronic musical instrument that can obtain a distortion effect that can provide a pleasant timbre change even when playing chords.

  The distortion device 100 according to the present embodiment is realized by the CPU 201 executing a program equipped with a distortion control function realized by the flowcharts of FIGS. The program may be recorded and distributed on a portable recording medium (not shown), or may be acquired from a network through a communication interface (not shown).

Regarding the above embodiment, the following additional notes are disclosed.
(Appendix 1)
A clipper unit that clips and outputs the input signal when the level of the input signal is equal to or higher than a predetermined clip level;
A mixing unit that mixes and outputs the output signal from the clipper unit and the input signal;
An envelope level detector for detecting an envelope level value of the input signal;
When the envelope level detected by the envelope level detection unit is within a predetermined region including the clipping level, the level of the output signal from the clipper unit is reduced and supplied to the mixing unit. A distortion device comprising: a control unit that controls to increase the level of the input signal.
(Appendix 2)
The distortion apparatus according to appendix 1, wherein the control unit controls the level of the output signal from the clipper unit to gradually decrease and the level of the input signal supplied to the mixing unit to gradually increase.
(Appendix 3)
The distortion device according to appendix 1 or 2, wherein the control unit gradually decreases the level of the output signal from the clipper unit by gradually decreasing the level of the input signal supplied to the clipper unit.
(Appendix 4)
A clipper unit that clips and outputs the input signal when the level of the input signal is equal to or higher than a predetermined clip level, and a mixture that mixes and outputs the output signal from the clipper unit and the input signal Distortion used in a distortion device comprising: a section, an envelope level detection section that detects an envelope level value of the input signal, and a level adjustment section that adjusts the level of the input signal supplied to the clipper section and the mixing section A control method, wherein the distortion device is
When the envelope level detected by the envelope level detection unit is within a predetermined region including the clipping level, the level of the input signal supplied to the clipper unit is reduced, and the mixing unit A distortion control method for controlling the level adjusting unit to increase the level of the supplied input signal.
(Appendix 5)
A clipper unit that clips and outputs the input signal when the level of the input signal is equal to or higher than a predetermined clip level, and a mixture that mixes and outputs the output signal from the clipper unit and the input signal And a level adjustment unit that adjusts the level of the input signal supplied to the clipper unit and the mixing unit. On the computer,
When the envelope level detected by the envelope level detection unit is within a predetermined region including the clipping level, the level of the input signal supplied to the clipper unit is reduced, and the mixing unit The program which performs the step which controls the said level adjustment part so that the level of the said input signal supplied may be increased.

100 Distortion device 101, 215, 312 Input terminal 102, 216, 314 Output terminal 103 Effect bypass indicator (Effect / Bypass Indicator)
104 Drive Control Knob (Drive Control)
105 Tone Control Knob (Tone Control)
106 Level Control Knob (Level Control)
107, 210 Pedal switch 201 CPU
202 ROM
203 RAM
204 DSP
205, 209 Amplifier 206, 213 A / D converter 207 Work memory 208 D / A converter 211 Flip-flop digital circuit 212 Control knob 214 System bus 301 Effect / bypass switching unit 302 CPU interface unit 303 Audio processing unit 304 Clipper input level detection 305 Effect / Bypass signal 306 Clipper input level signal 307 Clipper gain signal 308 Clean gain signal 309 Drive signal 310 Tone signal 311 Level signal 313 Bypass line 315 High pass filter (HPF)
316 Multiplier for drive 317 Multiplier for clipper gain 318 Clipper 319 Multiplier for clean gain 320 Adder 321 Low-pass filter (LPF) for tone adjustment
322 level multiplier 323 LPF for clipper gain smoothing
324 LPF for smooth gain smoothing
325 Rectifier 326 LPF
327 Multiplier Effect Effect Bypass CINPUT Clipper Input Level Register CGAIN Clipper Gain Register LGAIN Clean Gain Register DRIVE Drive Register TONE Tone Register LEVEL Level Register

Claims (5)

A clipper unit that clips and outputs the input signal when the level of the input signal is equal to or higher than a predetermined clip level;
A mixing unit that mixes and outputs the output signal from the clipper unit and the input signal;
An envelope level detector for detecting an envelope level value of the input signal;
When the envelope level detected by the envelope level detection unit is within a predetermined region including the clipping level, the level of the output signal from the clipper unit is reduced and supplied to the mixing unit. A distortion device comprising: a control unit that controls to increase the level of the input signal.   2. The distortion device according to claim 1, wherein the control unit controls to gradually decrease the level of the output signal from the clipper unit and gradually increase the level of the input signal supplied to the mixing unit.   The distortion device according to claim 1, wherein the control unit gradually decreases the level of the output signal from the clipper unit by gradually decreasing the level of the input signal supplied to the clipper unit. A clipper unit that clips and outputs the input signal when the level of the input signal is equal to or higher than a predetermined clip level, and a mixture that mixes and outputs the output signal from the clipper unit and the input signal Distortion used in a distortion device comprising: a section, an envelope level detection section that detects an envelope level value of the input signal, and a level adjustment section that adjusts the level of the input signal supplied to the clipper section and the mixing section A control method, wherein the distortion device is
When the envelope level detected by the envelope level detection unit is within a predetermined region including the clipping level, the level of the input signal supplied to the clipper unit is reduced, and the mixing unit A distortion control method for controlling the level adjusting unit to increase the level of the supplied input signal. A clipper unit that clips and outputs the input signal when the level of the input signal is equal to or higher than a predetermined clip level, and a mixture that mixes and outputs the output signal from the clipper unit and the input signal And a level adjustment unit that adjusts the level of the input signal supplied to the clipper unit and the mixing unit. On the computer,
When the envelope level detected by the envelope level detection unit is within a predetermined region including the clipping level, the level of the input signal supplied to the clipper unit is reduced, and the mixing unit The program which performs the step which controls the said level adjustment part so that the level of the said input signal supplied may be increased.