JP4385401B2 - Low frequency oscillation device and low frequency oscillation processing program - Google Patents

Description

  The present invention relates to a low frequency oscillation device and a low frequency oscillation processing program suitable for use as a sound source of an electronic musical instrument.

  As is well known, an electronic musical instrument is often provided with a low-frequency oscillating device for modifying a generated musical tone by periodically modulating musical tone elements such as pitch, tone color, and volume with a low-frequency signal. As this type of device, for example, Patent Document 1 gives an effect by randomly changing the oscillation frequency of a low-frequency signal and the modulation degree for modulating the frequency of the pitch with the low-frequency signal according to the key depression. A low-frequency oscillation device is disclosed.

JP-A-11-85157

By the way, since the apparatus disclosed in Patent Document 1 generates a random waveform level for each oscillation cycle of a low-frequency signal, it is suitable for giving an unexpected effect of extreme change. There is a problem that the intended effect cannot be imparted.
Accordingly, the present invention has been made in view of such circumstances, and a low-frequency oscillation device and a low-frequency oscillation device that can provide an unexpected effect of extreme change while providing an effect intended by the user to some extent. The object is to provide an oscillation processing program.

To achieve the above object, according to the invention of claim 1, the first and second waveform of each waveform segment, and the first designated Then monitor the percentage of waveform segment occupied in the two waveform segment, the Designation means for randomly designating a coefficient for determining a peak value for each of the first and second waveform sections within a designated change width; and the first and second waveform sections designated by the designation means Each of the waveforms is multiplied by a coefficient designated for each of the first and second waveform sections, and the ratio designating means designates the multiplied waveform for each of the first and second waveform sections. and LFO waveform generating means for generating a synthesized LFO waveform in accordance with the proportions, that in response to said LFO waveform LFO waveform generating means generates comprises a effect imparting means for effectively imparting modulates the generated musical tones, the Features .

According to a second aspect of the present invention, the waveform designating means for designating the waveform for each of the first and second waveform sections, and the ratio of the first waveform section in the first and second waveform sections are designated. A ratio specifying means, a change width specifying means for randomly specifying a coefficient for determining a peak value for each of the first and second waveform sections within a specified change width, and the waveform specifying means said first and second waveform of each waveform segment, a synthesized periodic waveform in proportion to the ratio specifying means specifies the change width designating means is specified for the peak value of the periodic waveform LFO waveform generation means for generating an LFO waveform multiplied by a coefficient for each of the first and second waveform sections, and the pitch, tone color, and volume of the generated musical sound according to the LFO waveform generated by the LFO waveform generation means Individually modulated and effective And effect imparting means for imparting, characterized by including the.

In the invention described in claim 3, the first and second waveform of each waveform segment, and the first designated percentage of the waveform segment of a result Moni occupied in the two waveform segment, the first and second waveform segment A designation step for randomly designating a coefficient for determining a peak value for each within a designated change width, and the first and second waveforms with respect to the designated waveform for each of the first and second waveform sections. Multiply the coefficients specified for each of the two waveform sections and generate an LFO waveform by combining the multiplied waveforms for the first and second waveform sections according to the ratio specified by the ratio specifying means. and LFO waveform generating step of, in response to the LFO waveform the generated, characterized in that to execute the effect imparting step to effectively impart modulates the generated musical tones, with computer.

According to a fourth aspect of the present invention, a waveform designating step for designating a waveform for each of the first and second waveform sections, and a ratio of the first waveform section in the first and second waveform sections are designated. A ratio specifying step ; a change width specifying step for randomly specifying a coefficient for determining a peak value for each of the first and second waveform sections within a specified change width; and the specified first and second A periodic waveform obtained by synthesizing a waveform for each second waveform section in accordance with the specified ratio, and for each of the specified first and second waveform sections with respect to a peak value of the periodic waveform . and LFO waveform generation step of generating a LFO waveform obtained by multiplying the coefficient in response to the generated LFO waveform, the pitch of the musical tones to be generated, and the effect imparting step to effectively granted a tone and volume modulated separately, with computer Fruit Characterized in that to.

According to the invention of claim 1 and 3, designated Then monitor the percentage of the first waveform segment occupying the first and second waveform and the both waveform segment of each waveform segment, the first and second When the coefficient for determining the peak value for each waveform section is randomly specified within the specified change width, the first and second waveforms with respect to the waveforms for the specified first and second waveform sections An LFO waveform is generated by synthesizing the coefficients of the first and second waveform sections multiplied according to the specified ratio, and the coefficient specified for each section is generated, and according to the generated LFO waveform. Since the effect is imparted by modulating the generated musical sound, it is possible to impart an effect of extreme changes that cannot be anticipated while giving the effect intended by the user to some extent, and to achieve a more expressive LFO effect. .

According to the second and fourth aspects of the invention, the waveform for each of the first and second waveform sections is designated, the ratio of the first waveform section to the first and second waveform sections is designated, and the first When the coefficient for determining the peak value for each of the first and second waveform sections is randomly specified within the specified change width, the waveforms for the first and second waveform sections are synthesized according to the specified ratio. The LFO waveform is generated by multiplying the specified coefficient for each of the first and second waveform sections specified for the peak value of the periodic waveform, and according to the generated LFO waveform. Since the tone, tone color, and volume of the generated musical tone are individually modulated to give the effect, the effect of the extreme change that cannot be expected can be given while giving the effect intended by the user to some extent, and more expression A powerful LFO effect can be achieved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A. Configuration (1) Overall Configuration FIG. 1 is a block diagram showing an overall configuration of an electronic musical instrument 10 according to an embodiment of the present invention. The electronic musical instrument 10 includes a keyboard 1, an operation unit 2, a CPU 3, a ROM 4, a RAM 5, a sound source 6, a D / A converter 7, and a sound system 8. The keyboard 1 generates performance information including a key-on / key-off signal, a key number (or note number), velocity, and the like corresponding to a press / release key operation (performance operation). The operation unit 2 includes various switches arranged on the musical instrument panel, and generates a switch event corresponding to the switch operation. As main switches arranged in the operation unit 2, there are a waveform selection switch, a synchronization mode selection switch, a play switch, and the like, and processing operations corresponding to these switch operations will be described in detail later.

  The CPU 3 sets the operation state of each part of the musical instrument based on the switch event generated in response to the switch operation of the operation unit 2, or commands (for example, a sound generation instruction command or a mute instruction command And the like are transmitted to the sound source 6 together with parameters stored in the RAM 5 (to be described later) to form a musical tone. The processing operation of the CPU 3 according to the gist of the present invention will be described later. The ROM 4 stores various control programs and control data that are loaded into the CPU 3. The various control programs referred to here include a main routine and switch processing described later.

  The RAM 5 is used as a work area for the CPU 3 and temporarily stores various register / flag data. Here, the contents of the main register temporarily stored in the RAM 5 will be described with reference to FIG. In this figure, the register Duty holds a parameter for designating the ratio of the waveform A section occupying in one entire LFO waveform cycle generated by an LFO waveform generator 63 (see FIG. 3) described later. The register WF_A holds a parameter (waveform number) that specifies a waveform table that forms an A section in the LFO waveform. The register RMin_A holds a random number minimum value in the A section in the LFO waveform. The register RMax_A holds a random number maximum value in the A section in the LFO waveform. The register WF_B holds a parameter for designating a waveform table that forms the B section in the LFO waveform. The register RMin_B holds a random number minimum value in the B section in the LFO waveform. The register RMax_B holds a random number maximum value in the B section in the LFO waveform.

  The flag SyncMode indicates a beat synchronization mode when “1”, and indicates a non-beat synchronization mode when “0”. The register Rate holds the read phase rate of the LFO waveform. The register Beat holds the number of beats when the LFO waveform is generated in beat synchronization. The register PD holds a pitch modulation degree to be given to a coefficient multiplier 64 (see FIG. 3) described later. The register FD holds a filter modulation degree to be given to a coefficient multiplier 65 (see FIG. 3) described later. The register AD holds a volume modulation degree to be given to a coefficient multiplier 66 (see FIG. 3) described later. The contents of the registers Duty to AD described above are parameters set by the user.

  The register WT_A holds the top address of the waveform table specified by the register WF_A. The register WTS_A holds the size of the waveform table specified by the register WF_A. The register WT_B holds the top address of the waveform table specified by the register WF_B. The register WTS_B holds the size of the waveform table specified by the register WF_B. The register PP holds the read phase position of the LFO waveform. The flag S is a random value setting processing flag, and the intended place will be described later. The register R holds a random value. The clock counter CC holds the count value of the timer clock. The register CC_MAX holds a clock count value corresponding to one bar length. The flag Play is a flag indicating that the performance is stopped when “0” and that the performance is being performed when “1”.

  Next, the configuration of the embodiment will be described with reference to FIG. 1 again. In FIG. 1, a sound source 6 is configured by a well-known waveform memory reading method, and reads and reads tone waveform data specified by parameters supplied from the CPU 3 among waveform data stored in its own internal memory. The waveform data is subjected to waveform modification according to the performance information supplied from the CPU 3 to generate musical sound data. Further, the tone generator 6 modulates the pitch, tone color and volume of the musical tone data with the LFO waveform generated according to the LFO generation parameter supplied from the CPU 3 and adds an effect. The D / A converter 7 converts the musical tone data output from the sound source 6 into an analog musical tone signal and outputs it. The sound system 8 performs filtering such as removing unnecessary noise from the musical sound signal output from the D / A converter 7, and then amplifies it to make it sound from the speaker.

(2) Configuration of Sound Source 6 Next, the configuration of the sound source 6 will be described with reference to FIG. The sound source 6 is composed of a known DSP. Therefore, FIG. 3 illustrates functional blocks in which each function of the microprogram executed in the DSP is regarded as a hardware image.
As shown in FIG. 3, the sound source 6 includes a waveform generator 67, a filter 68, an amplifier 69, and a mixer 70 provided in a plurality of systems corresponding to the sound generation channels. The waveform generator 67 is configured by a well-known waveform memory readout method, and reproduces waveform data of a specified tone color at a specified pitch in accordance with a sound generation command supplied from the CPU 3, while a pitch modulation signal supplied from a coefficient multiplier 64. The playback pitch is frequency-modulated accordingly. The coefficient multiplier 64 multiplies an LFO waveform supplied from an LFO waveform generator 63 described later by a pitch modulation degree PD given from the CPU 3 to generate a pitch modulation signal.

  The filter 68 includes a well-known DCF (digital control filter), and modulates the cutoff frequency in accordance with the cutoff frequency modulation signal supplied from the coefficient multiplier 65 to change the low-pass characteristic, thereby generating a waveform. A tone color change is given to the waveform data output from the device 67. The coefficient multiplier 65 multiplies an LFO waveform supplied from an LFO waveform generator 63, which will be described later, by a filter modulation degree FD supplied from the CPU 3 to generate a cutoff frequency modulation signal.

  The amplifier 69 variably controls the amplification factor according to the volume modulation signal supplied from the coefficient multiplier 66, and gives the volume change to the waveform data output from the filter 68. The coefficient multiplier 66 multiplies an LFO waveform supplied from an LFO waveform generator 63, which will be described later, by a volume modulation degree AD given from the CPU 3 to generate a volume modulation signal. The mixer 70 combines the outputs of the amplifiers 69 corresponding to the sound generation channels.

  As shown in FIG. 4, the LFO waveform generator 63 generates an LFO waveform in which one waveform period is divided into an A section and a B section. That is, the LFO waveform generator 63 includes various waveform tables assigned to these waveform sections A and B, and a waveform table having a waveform shape designated by the user-set waveform numbers WF_A (A section) and WF_B (B section). Generate a waveform with reference to.

  The waveform number WF_A (WF_B) designates four types of waveform shapes “0” to “3”. FIG. 5 illustrates the correspondence between the waveform number WF_A (WF_B) and the waveform shape. In the case of “0”, “triangular wave” illustrated in FIG. 5A, in the case of “1” “saw wave rising” illustrated in FIG. 5B, and in the case of “2”, FIG. In the case of “sawtooth wave down” and “3” illustrated in c), the waveform tables of “rectangular wave” illustrated in FIG. Therefore, the LFO waveform in FIG. 4 shows an example in which “sawtooth wave down (FIG. 5C)” is assigned to the waveform A section and “triangular wave (FIG. 5A)” is assigned to the waveform B section. .

  In the LFO waveform generator 63, the ratio of such waveform A and B sections is defined by the duty ratio. Specifically, the ratio of the waveform A section in the entire waveform cycle is designated by the value of the parameter Duty set by the user. For example, if a “rectangular wave” is assigned to the waveforms A and B and the parameter Duty is “0.6”, an LFO waveform with a duty ratio of 60% is obtained as in the example illustrated in FIG.

  Further, the LFO waveform generator 63 calculates Rmin + R (RMMax−) from the random number R (0 to 65535) read from the 16-bit random number table, the random number maximum value RMax and the random number minimum value Rmin set for each waveform section. RMin) / 65535 is calculated, and the LFO waveform level is randomly changed with a random value obtained therefrom. Note that the random number maximum value RMax_A and random number minimum value RMax_A in the waveform A section, and the random number maximum value RMax_B and random number minimum value RIn_B in the waveform B section are values set by the user.

  As described above, the LFO waveform generator 63 determines the waveform shape of each section of the waveforms A and B with the waveform numbers WF_A and WF_B, determines the ratio of the section of the waveform A occupying the entire waveform cycle by the parameter Duty, and further determines the maximum random number. Limiting the peak value width at which the LFO waveform level changes randomly according to the value RMax_A, the random number minimum value RMin_A, the random number maximum value RMax_B, and the random number minimum value RMin_B is unpredictable while giving the effect intended by the user to some extent. It is possible to generate an LFO waveform that also gives the effect of extreme changes.

  For example, the parameter Duty is “0.5”, the waveform number WF_A in the waveform A section is “0 (triangular wave)”, the random number maximum value RMax_A and the random number minimum value Rmin_A are “0”, and the waveform number WF_B in the waveform B section is “3”. (Rectangular wave) ", when the random number maximum value RMax_B is set to" 1.0 "and the random number minimum value Rmin_B is set to" -1.0 ", as shown in FIG. The waveform B section becomes an LFO waveform whose waveform level changes randomly within the range of “−1.0” to “1.0”.

  Further, for example, the parameter Duty is “0.25”, the waveform number WF_A of the waveform A section is “2 (sawtooth down)”, the random number maximum value RMax_A is “−0.5”, and the random number minimum value Rmin_A is “−1. FIG. 8 illustrates a case where “0”, the waveform number WF_B of the waveform B section is “0 (triangular wave)”, the random number maximum value RMax_B is “0.5”, and the random number minimum value RMin_B is “−0.5”. As shown, in the waveform A section, the sawtooth wave descending waveform that randomly changes in the range of the waveform level “−1.0” to “−0.5”, while in the waveform B section, the waveform level is “−0. An LFO waveform having a triangular waveform that randomly changes in the range of “5” to “0.5” is generated.

  The LFO waveform generator 63 generates an LFO waveform according to the outputs of the beat clock generator 61 and the phase generator 62, as shown in FIG. The phase generator 62 generates the phase position PP according to the flag SyncMode supplied from the CPU 3. The flag SyncMode indicates a beat synchronization mode when “1”, and indicates a non-beat synchronization mode when “0”.

  In the non-beat synchronization mode in which the flag SyncMode is “0”, the phase generator 62 accumulates the phase increment corresponding to the read phase rate of the LFO waveform stored in the register Rate to the previous phase position PP, and The phase position PP is calculated, and the LFO waveform reading is advanced according to the calculated current phase position PP. When the phase position PP obtained by accumulating the phase increments exceeds “1”, “1” is subtracted and set to the read phase position PP of the current LFO waveform.

In the beat synchronization mode in which the flag SyncMode is “1”, the phase generator 62 generates the phase position PP in synchronization with the beat output of the beat clock generator 61. The beat clock generator 61 outputs a beat clock at a timing corresponding to the user-specified number of beats Beat.
For example, if the timer count CC that accumulates the timer clock that is the minimum unit time is defined as “1 beat” when the timer count CC counts “96 clocks”, the timer count is counted when the beat number specified by the user is 4 beats. Each time the CC counts “384 clocks”, a beat clock is output.

B. Operation Next, the operation of the embodiment having the above-described configuration will be described. Hereinafter, the operation of the CPU 3 will be described with reference to FIGS. 9 to 10, and then the operation of the sound source 6 will be described with reference to FIGS. 11 to 12.

(1) Operation of CPU 3
<Main routine operation>
When the electronic musical instrument 10 having the above configuration is powered on, the CPU 3 executes the main routine shown in FIG. 9 and proceeds to step SA1 to reset various registers / flags stored in the RAM 5 and to set initial values. Then, initialization for instructing the sound source 6 to initialize various register flags is executed. When the initialization is completed, the process proceeds to step SA2, and the switch process corresponding to the switch operation in the operation unit 2 is performed. As will be described later, in the switch process, various parameters to be given to the LFO waveform generator 63 of the sound source 6 are set. In step SA3, a keyboard process for sending a sound generation / mute command to the sound source 6 in accordance with performance information generated by a key release operation of the keyboard 1 is executed. Subsequently, in step SA4, for example, after performing other processing such as playing music data specified by the user and performing automatically, the processing returns to step SA2, and thereafter, until the power is turned off, steps SA2 to SA2 are performed. Repeat SA4.

<Operation of switch processing>
Next, the operation of the switch process will be described with reference to FIG. When this processing is executed through step SA2 of the main routine described above, the CPU 3 executes processing corresponding to the operated switch type. Below, each operation | movement when the switch operation which sets a main parameter to the LFO waveform generator 63 of the sound source 6 is performed is described.

a. A Section Waveform Selection Switch Operation When the A section waveform selection switch operation is performed, the determination result in step SB1 is “YES”, and the flow proceeds to step SB2. In step SB2, the selected waveform number designating the waveform table assigned to the A section of the LFO waveform is stored in the register WF_A, and the head address and table size of the designated waveform table are stored in the register WT_A and the register WTS_A, respectively. To do.

b. B Section Waveform Selection Switch Operation When the B section waveform selection switch operation is performed, the determination result in step SB3 is “YES”, and the flow proceeds to step SB4. In step SB4, the selected waveform number designating the waveform table assigned to the B section of the LFO waveform is stored in the register WF_B, and the head address and table size of the designated waveform table are stored in the register WT_B and the register WTS_B, respectively. To do.

c. Synchronous mode selection switch operation When the synchronous mode selection switch operation is performed, the determination result in step SB5 becomes "YES", the process proceeds to step SB6, the flag SyncMode is inverted, and the register PP which holds the read phase position of the LFO waveform Is reset to zero and “1” is set to the random value setting processing flag S.

d. Play Switch Operation When the play switch operation is performed, the determination result in step SB7 is “YES”, the process proceeds to step SB8, the flag Play indicating that the performance is stopped / playing is reversed, and the clock counter CC is reset to zero.

  Then, the process proceeds to step SB9, for example, the parameter Duty for specifying the proportion of the waveform A section occupying the entire LFO waveform period, the random number maximum value RMax_A, the random number minimum value RMax_A, and the LFO waveform B section of the LFO waveform A section. This processing is completed after executing other switch processing for setting the random number maximum value RMax_B and the random number minimum value RMin_B.

(2) Operation of sound source 6
Next, the operation of the sound source 6 will be described with reference to FIGS. The tone generator 6 executes a beat timer process that realizes the function of the beat clock generator 61 and an LFO timer process that realizes the function of the LFO waveform generator 63. Hereinafter, each operation of the beat timer process and the LFO timer process will be described.

<Operation of beat timer processing>
The sound source 6 executes this process with a timer interrupt at regular intervals. When the interrupt execution timing is reached, the process proceeds to step SC1 shown in FIG. 11, and the clock counter CC that counts the timer clock is incremented and incremented. In step SC2, it is determined whether or not the accumulated value of the clock counter CC is greater than the register CC_MAX. Here, a clock count value corresponding to one bar length is held in the register CC_MAX. Therefore, in step SC2, it is determined whether one measure has elapsed. When one measure has elapsed, the determination result is “YES”, the process proceeds to step SC3, and the clock counter CC is reset to zero. On the other hand, if one measure has not elapsed, the determination result in step SC2 is “NO”, and this processing is completed.
Thus, in the beat timer processing, the clock counter CC is incremented at each timer interrupt execution timing until one bar elapses, the timer clock is accumulated, and the clock counter CC is reset to zero each time one bar elapses. It has become.

<Operation of LFO timer processing>
The sound source 6 executes this process with a timer interrupt at regular intervals. When the interrupt execution timing is reached, the process proceeds to step SD1 shown in FIG. 12, where the flag SyncMode is “1” and the flag Play is “1”. That is, it is determined whether the beat synchronization mode for generating the LFO waveform in synchronization with the automatic performance is set and the performance is currently being performed.

  When the beat synchronization mode is not set, that is, when the non-beat synchronization mode is set, or when the performance is not currently being performed, the determination result is “NO”, and the process proceeds to step SD2. In step SD2, the phase increment corresponding to the read phase rate of the LFO waveform stored in the register Rate is read from the table DP [Rate] and added to the register PP. When the value of the register PP to which the phase increment is added (LFO waveform read phase position) exceeds “1”, the value obtained by subtracting “1” from the register PP is used as the read phase position of the current LFO waveform. Store in register PP.

  On the other hand, if it is the beat synchronization mode in which the LFO waveform is generated in synchronization with the automatic performance and the current performance is being performed, the determination result in step SD1 is “YES”, and the process proceeds to step SD3. In step SD3, the value calculated by ((remainder of (CC / (96 × Beat))) / (96 × Beat) is stored in the register PP as the read phase position of the current LFO waveform. In the above equation, CC is the value of the clock counter CC counted by the beat timer process, Beat is the number of beats when the LFO waveform is generated in beat synchronization, and is a value set in the register Beat by the user.

  Next, in step SD4, it is determined whether or not the phase position PP is larger than the value of the register Duty, that is, whether or not the phase position PP is in the B section. Hereinafter, the description of the operation is divided into a process when the phase position PP is within the A section and a process when the phase position PP is within the B section.

a. When the phase position PP is within the A section
If the phase position PP is within the A section, the determination result in step SD4 is “NO”, and the flow proceeds to step SD5. In step SD5, it is determined whether or not the flag S is “0”. Since the flag S is “1” at the time of initial setting, if it is the first pass, the determination result here is “NO”, and the process proceeds to step SD6. In the next and subsequent passes, as will be described later, the flag S is reset to zero in step SD6. Therefore, the determination result in step SD5 is “YES”, and the process proceeds to step SD7.

  In step SD6 executed in the first pass, the flag S is reset to zero, and the random value read from the 16-bit random number table is stored in the register R. Further, after storing the random value adjusted by the equation Rmin_A + (R / 65535) × (RMax_A−RMin_A) in the register R based on the random number maximum value RMax_A and the random number minimum value Rmin_A set in the waveform A section, Update the random number table read pointer.

  Next, in step SD7, from the waveform table assigned to the A section of the LFO waveform based on the start address (WT_A), table size (WTS_A), phase position PP and Duty of the waveform table assigned to the A section of the LFO waveform. The waveform value WT_A [WTS_A × PP / Duty] corresponding to the phase position PP is read, and the random value of the register R is multiplied by this to calculate the LFO waveform value v. Note that the random value of the register R here refers to the random value R adjusted in accordance with the random number maximum value RMax_A and the random number minimum value Rmin_A in step SD6.

  Thereafter, the process proceeds to step SD8, in which the pitch modulation degree stored in the register PD, the filter modulation degree stored in the register FD, and the volume modulation degree stored in the register AD are respectively multiplied by the LFO waveform value v to perform pitch modulation. A signal PM, a cut-off frequency modulation signal FM, and a volume modulation signal AM are generated. The pitch modulation signal PM, the cut-off frequency modulation signal FM, and the volume modulation signal AM correspond to the outputs of the coefficient multipliers 64 to 66, and are sent to the waveform generator 67, the filter 68, and the amplifier 69, respectively, for the main processing. Finish.

b. When the phase position PP is in the B section
If the phase position PP is in the B section, the determination result in step SD4 is “YES”, and the process proceeds to step SD9. In step SD9, it is determined whether or not the flag S is “1”. Since the flag S is reset to zero when the processing of the waveform A section described above is completed, the determination result is “NO” in the first pass, and the process proceeds to step SD10. In the next and subsequent passes, as described later, since the flag S is set to “1” in step SD10, the determination result in step SD9 is “YES”, and the process proceeds to step SD11.

  In step SD10 executed in the first pass, the flag S is set to “1”, and the random value read from the 16-bit random number table is stored in the register R. Further, after storing the random value adjusted by the formula Rmin_B + (R / 65535) × (RMax_B−RMin_B) in the register R based on the random number maximum value RMax_B and the random number minimum value Rmin_B set by the user in the waveform B section, Update the random number table read pointer.

  Next, in step SD11, from the waveform table assigned to the B section of the LFO waveform based on the top address (WT_B), table size (WTS_B), phase position PP and Duty of the waveform table assigned to the B section of the LFO waveform. The waveform value WT_B [WTS_B × (PP−Duty) / (1−Duty)] corresponding to the phase position PP is read and multiplied by the random value of the register R to calculate the LFO waveform value v. Note that the random value of the register R here refers to the random value R adjusted in accordance with the random number maximum value RMax_B and the random number minimum value RMin_B in step SD10.

  Thereafter, the process proceeds to step SD8, in which the pitch modulation degree stored in the register PD, the filter modulation degree stored in the register FD, and the volume modulation degree stored in the register AD are respectively multiplied by the LFO waveform value v to perform pitch modulation. A signal PM, a cut-off frequency modulation signal FM, and a volume modulation signal AM are generated. The pitch modulation signal PM, the cut-off frequency modulation signal FM, and the volume modulation signal AM correspond to the outputs of the coefficient multipliers 64 to 66, and are sent to the waveform generator 67, the filter 68, and the amplifier 69, respectively, for the main processing. Finish.

  As described above, in this embodiment, after determining the waveform shape for each section of the LFO waveform divided into the A section and the B section, the ratio of the waveform A section to the entire waveform period is determined by the parameter Duty. Furthermore, according to the LFO waveform obtained by restricting the random change width of the LFO peak value in the A section and the random change width of the LFO peak value in the B section, the effect is obtained by modulating the pitch, tone color and volume of the generated musical sound. Since it is given, it is possible to give the effect of extreme changes that cannot be anticipated while giving the effect intended by the user to some extent, and it is possible to achieve a more expressive LFO effect. .

It is a block diagram which shows the whole structure of one Embodiment by this invention. 4 is a diagram showing a configuration of main register / flag data stored in a RAM 5; FIG. 3 is a block diagram showing a configuration of a sound source 6. FIG. It is a figure which shows the example of a waveform for demonstrating the A section and B section of a LFO waveform. It is a figure which shows the waveform shape corresponding to waveform number WF_A (WF_B). It is a figure which shows an example of a LFO waveform with a duty ratio of 60%. It is a figure which shows an example of LFO waveform generation. It is a figure which shows an example of LFO waveform generation. It is a flowchart which shows operation | movement of the main routine which CPU3 performs. It is a flowchart which shows the operation | movement of the switch process which CPU3 performs. It is a flowchart which shows the operation | movement of the beat timer process which the sound source 6 performs. It is a flowchart which shows the operation | movement of the LFO timer process which the sound source 6 performs.

Explanation of symbols

1 keyboard 2 operation unit 3 CPU
4 ROM
5 RAM
6 sound source 7 D / A converter 8 sound system 10 electronic musical instrument 61 beat clock generator 62 phase generator 63 LFO waveform generator 64-66 coefficient multiplier 67 waveform generator 68 filter 69 amplifier 70 mixer

Claims (4)

First and second waveform of each waveform segment, and the said specified percentage of the first waveform segment Then Moni occupying both waveform segment, for determining the first and second peak value of each waveform segment A specifying means for randomly specifying a coefficient within a specified change width ;
Multiplying the waveform for each of the first and second waveform sections specified by the specifying means by a coefficient specified for each of the first and second waveform sections, and the multiplied first and second waveforms LFO waveform generating means for generating an LFO waveform obtained by synthesizing the waveform for each second waveform section according to the ratio specified by the ratio specifying means ;
An effect applying means for modulating the generated musical sound according to the LFO waveform generated by the LFO waveform generating means ,
A low-frequency oscillation device comprising: Waveform designating means for designating a waveform for each of the first and second waveform sections;
A ratio designating unit for designating a ratio of the first waveform section in the first and second waveform sections;
Change width specifying means for randomly specifying a coefficient for determining the peak value for each of the first and second waveform sections within a specified change width;
A periodic waveform obtained by synthesizing the waveforms of the first and second waveform sections specified by the waveform specifying means in accordance with the ratio specified by the ratio specifying means, and for the peak value of the periodic waveform LFO waveform generating means for generating an LFO waveform multiplied by a coefficient for each of the first and second waveform sections specified by the change width specifying means;
Effect imparting means for individually modulating the pitch, tone color and volume of the generated musical sound according to the LFO waveform generated by the LFO waveform generating means ;
A low-frequency oscillation device comprising: First and second waveform of each waveform segment, and the said specified percentage of the first waveform segment Then Moni occupying both waveform segment, for determining the first and second peak value of each waveform segment A specified step for randomly specifying a coefficient within a specified change width ; and
Multiplying the specified waveform for each of the first and second waveform sections by a coefficient specified for each of the first and second waveform sections, and the multiplied first and second waveforms An LFO waveform generation step for generating an LFO waveform obtained by synthesizing the waveform for each waveform section in accordance with the ratio specified by the ratio specifying means ;
In accordance with the generated LFO waveform, an effect applying step of modulating the generated musical sound to give an effect ;
A low-frequency oscillation processing program characterized by causing a computer to execute the program. A waveform designating step for designating a waveform for each of the first and second waveform sections;
A ratio designating step of designating a ratio of the first waveform section in the first and second waveform sections;
A change width specifying step of randomly specifying a coefficient for determining the peak value for each of the first and second waveform sections within a specified change width;
The waveform of said specified first and every second waveform segment, a synthesized periodic waveform according to the ratio of the specified, the first, which is the specified relative peak value of the periodic waveform And an LFO waveform generation step for generating an LFO waveform multiplied by a coefficient for each second waveform section;
Depending on the generated LFO waveform, the effect imparting step to effectively impart pitch of generating musical tones, the tone and volume by modulating individually,
A low-frequency oscillation processing program characterized by causing a computer to execute the program.

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