JP5115800B2 - 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 apparatus, for example, in Patent Document 1, the waveform shape of each section of the LFO waveform divided into the A section and the B section is determined, and then the ratio of the waveform A section occupying the entire waveform period by the parameter Duty Further, an LFO waveform obtained by limiting 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 is generated, and is generated according to the generated LFO waveform. Disclosed is a low-frequency oscillator that modulates the pitch, tone color, and volume of a musical sound to provide an effect intended by the user to some extent while also providing an unexpected and unexpected change effect. .

JP 2006-58595 A

  By the way, in recent electronic musical instruments, the number of simultaneously operating LFO waveforms used to generate a periodic modulation effect is increasing with the increase in the number of simultaneous sounds, the number of timbres that sound simultaneously, or the diversification of modulation targets. The current situation is that it places a heavy burden on the processor (CPU or DSP) of the sound source. For this reason, in order to reduce the load on the sound source, a method for stopping the output of the LFO waveform in the mute state is necessary.

  When the low-frequency oscillation device is always in operation, as shown in FIG. 10, the LFO waveform having the phase corresponding to the sounding period indicating the sounding is the modulation waveform, and the depth (amplitude) corresponding to the phase is changed. A modulation effect is obtained. On the other hand, for the purpose of reducing the load on the sound source, if the low frequency oscillation device is operated only during sound generation, as shown in FIG. 11, the low frequency oscillation device is activated each time the key is pressed. The phase of the LFO waveform output from the low-frequency oscillation device is reset to the head each time, and therefore, the modulation waveform gives a monotonous modulation effect.

Specifically, for example, a filter characteristic for controlling the tone color of a musical tone to be generated while setting the period of the LFO waveform to a relatively long time of 10 seconds and repeating the sound for a short time of about 0.5 seconds. Is changed by the LFO waveform, the phase of the LFO waveform is reset to the head each time the key is pressed, so that the timbre change becomes uniform and monotonous. In other words, in other words, there is a problem that the load on the sound source cannot be reduced while maintaining the unique modulation effect derived from the long-period LFO waveform.

  The present invention has been made in view of such circumstances, and a low-frequency oscillation device and a low-frequency oscillation capable of reducing the load on a sound source while maintaining a unique modulation effect derived from a long-period LFO waveform The purpose is to provide a processing program.

In order to achieve the above object, according to the first aspect of the present invention, LFO waveform generating means for generating an LFO waveform and whether the state of the LFO waveform is in a stop state, a normal operation state, or an operation stop preparation state. Storage means for storing state information to be indicated, state determination means for determining whether the state information stored in the storage means is in a normal operation state or an operation stop preparation state at a predetermined cycle, and the state information by the state determination means Is determined to be in a normal operating state, the sound detection means for detecting the presence or absence of the sound generated by the LFO waveform generated by the LFO waveform generation means, and the sound generation by the sound detection means When it is detected that the state information is not present, the state information stored in the storage unit is set to the operation stop preparation state, and the state information is detected by the state determination unit. When it is determined that the information is in an operation stop ready state, the stored state information is set to a stop state, and stop instruction means for instructing the LFO waveform generation means to stop generating the LFO waveform; and the storage means And a restart instruction means for instructing the LFO waveform generation means to resume the output of the LFO waveform when the musical sound is instructed to be sounded. Features.

In the invention according to claim 2 subordinate to claim 1, the state determination means stores the state information stored in the storage means every time the LFO waveform generation means generates an LFO waveform for one cycle. It is characterized by determining whether it is a normal operation state or an operation stop preparation state .

  In the invention according to claim 3, which is dependent on claim 1, the restart instruction means sets a random number generated based on a random function as an initial phase of the LFO waveform and instructs the LFO waveform generation means to resume output. It is characterized by that.

  In the invention according to claim 4, which is dependent on claim 1, the LFO waveform generated by the LFO waveform generating means modulates at least one of a pitch, tone color and volume of a tone to be generated. And

In a fifth aspect of the present invention, a computer used as a low-frequency oscillation device having storage means for storing state information indicating whether the LFO waveform is in a stopped state, a normal operating state, or an operating stop preparation state. , An LFO waveform generation process for generating the LFO waveform , a state determination process for determining whether the state information stored in the storage means is a normal operation state or an operation stop preparation state at a predetermined period, and the state determination process When it is determined that the state information is in a normal operation state, the sound generation detection process for detecting the presence or absence of the sound generated by the LFO waveform generated by the LFO waveform generation process and the sound generation detection process When it is detected that there is no musical sound, the control process for setting the state information stored in the storage means to the operation stop preparation state, When it is determined by the state determination process that the state information is in the operation stop preparation state, the stored state information is set to the stop state, and a stop instruction for instructing the LFO waveform generation process to stop generating the LFO waveform And a restart instruction process for instructing the LFO waveform generation process to resume the output of the LFO waveform when the state information stored in the storage means indicates a stopped state and when the tone generation instruction is issued. characterized in that to execute the door in a computer.

  In the present invention, it is possible to reduce the load on the sound source while maintaining a unique modulation effect derived from the long-period LFO waveform.

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, a MIDI interface 2, a switch unit 3, a CPU 4, a ROM 5, a RAM 6, a sound source 7, a D / A converter 8, and a sound system 9. The keyboard 1 generates performance information composed of 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 MIDI interface 2 exchanges MIDI data with an external MIDI device such as a MIDI keyboard under the control of the CPU 4.

The switch unit 3 includes various switches arranged on the musical instrument panel, and generates a switch event corresponding to the switch operation. The CPU 4 sets the operating state of each part of the musical instrument based on the switch event supplied from the switch unit 3, and also provides performance information supplied from the keyboard 1 (or MIDI data supplied from an external MIDI device via the MIDI interface 2). Based on the above, the sound source 7 is instructed to generate a musical sound. Further, the CPU 4 generates an LFO waveform for modulating the pitch, tone color and volume of the musical tone data generated by the sound source 7. The processing operation of the CPU 4 according to the gist of the present invention will be described later.

The ROM 5 stores various control programs and control data that are loaded into the CPU 4. The various control programs referred to here include a main routine, envelope processing, LFO processing, and note-on processing, which will be described later. The RAM 6 is used as a work area for the CPU 4 and temporarily stores various register / flag data. Here, the configuration of main registers provided in the RAM 5 will be described with reference to FIG.

In FIG. 2, the register part temporarily stores a part number for designating any one of 32 timbre parts that can be simultaneously generated in the sound source 7 described later. The register voice temporarily stores a voice number designating one of 64 sound generation channels (voices) included in the sound source 7. The register VPT [voice] temporarily stores a part number for designating a timbre part to which a sound generation channel designated by the voice number of the register voice is assigned.

The register AVC [part] temporarily stores the number of voices currently being generated in the timbre part specified by the part number of the register part. The register LPH [part] temporarily stores the current phase value of the LFO waveform assigned to the timbre part specified by the part number of the register part. The register LRR [part] temporarily stores the speed (change rate) of the LFO waveform assigned to the timbre part specified by the part number of the register part.

The register LST [part] temporarily stores a status value indicating the state of the LFO waveform assigned to the timbre part specified by the part number of the register part. The status value indicates a stop state when “0”, a normal operation state when “1”, and an operation stop preparation state when “2”. The register EST [voice] temporarily stores a state value of an envelope generator EG (described later) in the sound generation channel designated by the voice number of the register voice. When the state value is “0”, the sound generation is stopped, and when the state value is “1”, the sound is being generated. The register ELV [voice] temporarily stores the envelope level of the envelope generator EG in the sound generation channel specified by the voice number of the register voice.

  Next, the configuration of the embodiment will be described with reference to FIG. 1 again. In FIG. 1, a sound source 7 is configured by a well-known waveform memory reading method, and generates waveform data of tone color, pitch and volume specified by parameters supplied from the CPU 4, and the generated waveform data by the CPU 4. The musical sound data W to which the modulation effect is applied according to the LFO waveform supplied from the is output. The D / A converter 8 converts the musical sound data W output from the sound source 7 into an analog musical signal and outputs it. The sound system 9 performs filtering such as removing unnecessary noise from the musical sound signal output from the D / A converter 8, and then amplifies it to make it sound from the speaker.

(2) Configuration of Sound Source 7 Next, the configuration of the sound source 7 will be described with reference to FIGS. The sound source 7 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. In FIG. 3, a low-frequency oscillation device 80 (hereinafter referred to as LFO 80) and envelope generators 71 to 73 (hereinafter referred to as EG 71 to 73) are illustrated as components of the sound source 7 for convenience. The LFO 80 and the EGs 71 to 73 are functions implemented by the processing of the CPU 4.

In FIG. 3, an EG 71 generates an envelope waveform for pitch control. The adder 74 supplies a pitch modulation signal obtained by adding the LFO waveform output from the LFO 80 and the envelope waveform for pitch control output from the EG 71 to the waveform generator 75. The waveform generator 75 is configured by a well-known waveform memory reading method, reads waveform data of a specified tone color at a specified pitch according to parameters supplied from the CPU 4, and adds the pitch of the read waveform data to an adder 74. Is modulated in accordance with a pitch modulation signal supplied from.

The EG 72 generates an envelope waveform for timbre control (for cut-off frequency control). The adder 76 supplies the filter 77 with a cut-off frequency modulation signal obtained by adding the LFO waveform output from the LFO 80 and the tone waveform control envelope waveform output from the EG 72. The filter 77 is composed of a well-known DCF (digital control filter), and changes the low-pass characteristic by modulating the cutoff frequency of the DCF in accordance with the cutoff frequency modulation signal supplied from the adder 76, thereby changing the waveform. A tone color change is given to the waveform data which the generator 75 outputs.

The EG 73 generates an envelope waveform for volume control. The adder 78 supplies a volume modulation signal obtained by adding the LFO waveform output from the LFO 80 and the volume control envelope waveform output from the EG 73 to the amplifier 79. The amplifier 79 variably controls the amplification factor according to the volume modulation signal supplied from the adder 78, and gives a volume change to the waveform data output from the filter 77.

  The above components 71 to 79 form one sound generation channel (voice). That is, as shown in FIG. 4, 64 sets of sound generation channels are formed, and these are dynamically assigned to constitute a part sound source 70 for 32 timbres. In FIG. 3, an LFO 80 that generates an LFO waveform is provided corresponding to each of these 32 sets of part sound sources. The mixer 90 adds the waveform data generated by each of the 32 sets of part sound sources 7 and outputs the musical sound data W.

(3) Function Overview of LFO 80 Next, the function of the LFO 80 will be outlined with reference to FIG. Note that the functions of the LFO 80 are implemented by LFO processing and note-on processing executed by the CPU 4. Details of the LFO processing and the note-on processing will be described later. The LFO 80 generates an LFO waveform (triangular wave) shown in FIG. Specifically, for each timbre part, the LFO waveform speed (rate of change) of the register LRR [part] is added to the LFO waveform phase of the register LPH [part] at regular intervals to update the readout phase, and the updated readout The phase LFO waveform value is output.

  In the LFO 80, a checkpoint is provided at the beginning of each period after the first period of the LFO waveform. For example, as shown in FIG. 5, the key is pressed between checkpoint 1 and checkpoint 2 (operation stop preparation state). If the sound generation instruction is not generated, the check point 2 is stopped and the output of the LFO waveform is stopped. Further, in the LFO 80, when a sound generation instruction is generated by pressing a key while the LFO waveform is stopped, the generation of the LFO waveform is resumed with a random phase.

  As described above, in the LFO 80, after all the sound generations are muted, if no sound generation instruction is generated during the checkpoint period (operation stop preparation state) for one LFO waveform cycle, the LFO 80 enters the stopped state. When the output of the waveform is stopped and a sounding instruction is generated by pressing the key while the LFO waveform is stopped, the generation of the LFO waveform is resumed with a random phase, so that the unique modulation effect derived from the long-period LFO waveform is maintained. Can also reduce the load on the sound source.

B. Operation Next, the operation of the embodiment will be described with reference to FIGS. In the following, the operation of the main routine executed by the CPU 4 as an overall operation will be described with reference to FIG. 6, and the operations of envelope processing and LFO processing executed by the CPU 4 during execution of this main routine will be described with reference to FIGS. This will be described with reference to FIG. The operation of note-on processing called from the main routine will be described with reference to FIG.

(1) Operation of Main Routine FIG. 6 is a flowchart showing the operation of the main routine executed by the CPU 4. When the electronic musical instrument 10 having the above-described configuration is powered on, the CPU 4 proceeds to step SA1 of the main routine shown in FIG. 6 to reset various registers / flags stored in the RAM 6 and to set initial values. Then, initialization for instructing the sound source 7 to initialize various registers and flags is executed.

When the initialization is completed, the process proceeds to step SA2, and a switch process corresponding to the switch operation of the switch unit 3 is performed. In this switch processing, for example, a parameter for generating a musical tone of a timbre selected by operating a timbre selection switch is set in the sound source 7. Specifically, a filter coefficient for supplying a read start address of the waveform data of the designated tone color to the waveform generator 75 or setting a cutoff frequency corresponding to the designated tone color is supplied to the filter 77.

  Next, in step SA3, it is determined whether or not there is a key event. If no key operation is performed on the keyboard 1 and no key event occurs, the process returns to step SA2. When a key-on event is generated by pressing the keyboard 1, a note-on process (described later) is executed via step SA4, and then the process returns to step SA2. If a key-off event occurs due to the key release of the keyboard 1, the process proceeds to step SA5, and after performing note-off processing for instructing the sound source 7 to mute the musical sound produced at the pitch of the key released. Then, the process returns to step SA2. Thereafter, steps SA2 to SA5 are repeated until the electronic musical instrument 10 is powered off.

(2) Operation of Envelope Processing FIG. 7 is a flowchart showing an operation of envelope processing executed by the CPU 4 at predetermined intervals by a timer interrupt. At the interrupt timing, the CPU 4 repeats the processing from the loop start of step SB1 to the loop end of step SB7 shown in FIG. 7 for 64 sound generation channels (voice numbers 0 to 63 of the register voice). That is, steps SB2 to SB6 are executed for each tone generation channel.

  First, in step SB2, whether or not the state value of the EG 73 (see FIG. 3) stored in the register EST [voice] and designated by the voice number of the register voice is “0” (sound generation stopped state) is determined. to decide. If the sound generation is stopped, the determination result is “YES”, and the process proceeds to the end of the loop in step SB7. On the other hand, if the sound is being generated, the determination result in step SB2 is “NO”, and the process proceeds to step SB3 to execute the envelope update process. In the envelope update process, the envelope read phase of the EG 73 is incremented to update the envelope waveform for volume control.

  Subsequently, in step SB4, whether or not the envelope level of the EG 73 in the sound generation channel stored in the register ELV [voice] and specified by the voice number of the register voice is “0”, that is, specified by the voice number of the register voice. It is determined whether the sound channel to be played has reached the mute state. If the mute state has not been reached, the determination result is “NO”, and the process proceeds to the end of the loop of step SB7. However, if the mute state has been reached, the determination result of step SB4 is “YES”. Proceed to SB5.

  In step SB5, as the sound generation channel designated by the voice number of the register voice reaches the mute state, the value “0” representing the sound generation stop state is stored in the register EST [voice]. Next, in step SB6, the part number specifying the timbre part to which the tone generation channel specified by the voice number of the register voice is assigned is read from the register VPT [voice] and stored in the register part. In step SB6, since the number of voices being generated in the timbre part specified by the part number of the register part is reduced by one, the number of voices in the register AVC [part] is subtracted by one and the register AVC [part ] Is updated, and then the process proceeds to the end of the loop of step SB7.

  As described above, in the envelope processing, the sound volume control envelope waveform for each sound generation channel (voice) is updated every predetermined cycle, and there is a sound generation channel that has reached the mute state with the envelope waveform level “0”. In this case, a value “0” representing the sound generation stop state is stored in the register EST [voice], and the number of voices of the timbre part to which the muted sound generation channel is assigned is subtracted by 1 to register AVC [part]. Update.

(3) Operation of LFO Process FIG. 8 is a flowchart showing the operation of the LFO process executed by the CPU 4 at predetermined intervals by a timer interrupt. At the interrupt timing, the CPU 4 repeats the processing from the start of the loop at step SC1 to the end of the loop at step SC14 shown in FIG. 8 for each of the 32 tone colors (part numbers 0 to 31 of the register part). That is, steps SC2 to SC13 are executed for each timbre part.

  In step SC2, whether or not the status value indicating the state of the LFO waveform stored in the register LST [part] and assigned to the timbre part specified by the part number of the register part is “0” (stopped state). to decide. If the LFO waveform is not output, the determination result is “YES”, and the process proceeds to the loop end of step SC14. On the other hand, if the status value is “1” in the normal operation state or the status value is “2”, the determination result in step SC2 is “NO”, and the process proceeds to step SC3.

In step SC3, the speed (change rate) of the LFO waveform of the same timbre part is added to the current phase value of the LFO waveform stored in the register LPH [part] and assigned to the timbre part specified by the part number of the register part. The value of the register LRR [part] to be held is added to calculate a new read phase ph. Next, in step SC4, it is determined whether or not the current phase value of the LFO waveform stored in the register LPH [part] is greater than “256”. That is, in the present embodiment, the range of the phase value of the LFO waveform is set to “0” to “255”, and it is determined here whether or not the reading of the LFO waveform for one cycle has been completed. If the LFO waveform has not been read for one cycle, the determination result is “NO”, and the flow proceeds to step SC10 described later.

  On the other hand, when the LFO waveform has been read for one cycle, the determination result in step SC4 is “YES”, and the flow proceeds to step SC5. In step SC5, in order to perform so-called loop reproduction in which the LFO waveform is repeatedly read from the top, “256” is subtracted from the current phase value of the LFO waveform stored in the register LPH [part] to calculate a new readout phase ph. To do.

Next, at step SC6, whether the status value indicating the state of the LFO waveform stored in the register LST [part] and assigned to the timbre part specified by the part number of the register part is “1” (normal operating state). Judge whether or not. That is, as shown in FIG. 5, the check point 1 in which the LFO waveform has been read for one cycle is in the normal operation state with the status value “1”, or the check point 2 in which the LFO waveform has been read for one cycle. It is determined which of the operation stop preparation states whose status value is “2”. Hereinafter, the description of the operation will be made separately for the case of the normal operation state at the check point 1 and the case of the operation stop preparation state at the check point 2.

<In normal operation at checkpoint 1>
When the check point 1 is in the normal operation state, the determination result in step SC6 is “YES”, and the process proceeds to step SC7. In step SC7, it is determined whether the number of voices currently sounding in the timbre part stored in the register AVC [part] and designated by the part number of the register part is "0", that is, whether all sound generation channels are muted. To do. If all the sound generation channels are not muted, the determination result is “NO”, and the process proceeds to Step SC10 described later.

  On the other hand, if all sound generation channels are muted, the determination result in step SC7 is “YES”, and the process proceeds to step SC8, where the LFO waveform assigned to the timbre part specified by the part number in the register part is activated. After storing the status value “2” indicating the stop preparation state in the register LST [part], the process proceeds to Step SC10 described later.

<When checkpoint 2 is in preparation for shutdown>
If the operation is in the operation stop preparation state at the check point 2, the determination result in step SC6 is “NO”, the process proceeds to step SC9, and the LFO waveform assigned to the timbre part specified by the part number in the register part is stopped. After storing the status value “0” indicating the presence in the register LST [part], the process proceeds to step SC10.

As described above, when the LFO waveform is read out for one cycle and is in the normal operation state and all the sound generation channels are muted, the operation state is shifted to the operation stop preparation state. If it is in the operation stop preparation state at the check point 2 that has been read for the period, the state transits to the stop state. When such state transition is completed, the process proceeds to step SC10, where the calculated read phase ph is used as the current phase value of the LFO waveform assigned to the timbre part specified by the part number of the register part, and the register LPH [part]. To store.

  Next, in step SC11, a pitch modulation signal obtained by adding the LFO waveform read according to the current phase value of the register LPH [part] and the envelope waveform for pitch control output from the EG 71 (see FIG. 3) is used as a waveform. The pitch process supplied to the generator 75 (refer FIG. 3) is performed. Note that the pitch process in step SC11 is not executed when the process shifts to the stop state.

  Subsequently, in step SC12, a timbre modulation signal obtained by adding the LFO waveform read according to the current phase value of the register LPH [part] and the timbre control envelope waveform output from the EG 72 (see FIG. 3) is filtered. The filter processing supplied to 77 (see FIG. 3) is executed. It should be noted that the filtering process in step SC12 is not executed when transitioning to the stopped state.

In step SC13, a volume modulation signal obtained by adding the LFO waveform read in accordance with the current phase value of the register LPH [part] and the volume control envelope waveform output from the EG 73 (see FIG. 3) is amplified by the amplifier 79. After executing the amplifier process supplied to (see FIG. 3), the process proceeds to the loop end of step SC14. It should be noted that the amplifier process in step SC13 is not executed when transitioning to the stop state.

(4) Operation of Note On Process FIG. 9 is a flowchart showing the operation of the note on process. When this process is executed through step SA4 (see FIG. 6) of the main routine described above, the CPU 4 proceeds to step SD1 shown in FIG. Execute key assigner processing to determine (voice). As a result, a voice number that designates a sound generation channel to which sound generation is assigned is stored in the register voice.

  Next, in step SD2, whether or not the state value of the EG 73 (see FIG. 3) in the sound generation channel stored in the register EST [voice] and designated by the voice number of the register voice is “0” (sound generation stopped state). Judging. That is, it is determined whether or not the sound generation channel assigned with sound generation in step SD1 is in a sound generation stop state. If the sound generation is stopped, the determination result is “YES”, and the process proceeds to Step SD4 described later.

On the other hand, if the sound channel assigned to be sounded in step SD1 is still sounding, the determination result in step SD2 is “NO”, and the process proceeds to step SD3, where the sound channel specified by the voice number of the register voice is set. After executing the voice stop process instructing the sound source 7 to forcibly mute the sound, the process proceeds to step SD4. In step SD4, the state value “1” indicating that the sound is being generated is stored in the register EST [voice]. As a result, the sound generation channel newly assigned with sound generation by the key assigner process in step SD1 is set to a sounding state.

Subsequently, in step SD5, the part number of the timbre part to which the tone generation channel designated by the voice number of the register voice is assigned is read from the register VPT [voice] and stored in the register part, and the part number of the register part is used. Since the number of voices being sounded by the specified timbre part increases by one, the number of voices in the register AVC [part] is incremented (AVC [part] +1).

  Next, at step SD6, whether or not the status value indicating the state of the LFO waveform stored in the register LST [part] and assigned to the timbre part specified by the part number of the register part is “0” (stopped state). Determine whether. If it is in the stop state, the determination result is “YES”, and the process proceeds to step SD7, where the random number generated based on the random function is stored in the register phase as the initial phase of the LFO waveform, and in the subsequent step SD8, the value of this register phase is stored. Is stored in the register LPH [part] as the current phase value of the LFO waveform assigned to the timbre part specified by the part number of the register part, and the process proceeds to step SD9. As described above, when a sound generation instruction is generated by pressing a key while the LFO waveform is stopped, the generation of the LFO waveform is resumed with a random phase.

  On the other hand, when the value of the register LST [part] is not “0”, that is, the LFO waveform assigned to the timbre part specified by the part number of the register part is in the normal operation state (status value “1”) or ready for operation stop. If it is in the state (status value “2”), the determination result in step SD6 is “NO”, the process proceeds to step SD9, and the status value “1” is stored in the register LST [part]. In other words, if the LFO waveform of the timbre part before sounding assignment is in the normal operation state, the LFO waveform of the same timbre part maintains the normal operation state even when sounding assignment is made, while the sound part of the timbre part before the sound assignment is assigned. If the LFO waveform is in the operation stop preparation state, the LFO waveform of the same tone color part is changed to the normal operation state in accordance with the sound generation assignment.

  Thereafter, the process proceeds to step SD10, in which the waveform generator 75 (see FIG. 3) is instructed to generate waveform data of the pitch of the depressed key, and is read according to the current phase value of the register LPH [part]. The pitch is initially set so that a pitch modulation signal obtained by adding the LFO waveform and the envelope waveform for pitch control output from the EG 71 (see FIG. 3) is supplied to the waveform generator 75.

  Subsequently, in step SD11, a timbre modulation signal obtained by adding the LFO waveform read in accordance with the current phase value of the register LPH [part] and the timbre control envelope waveform output from the EG 72 (see FIG. 3) is filtered. 77 (see FIG. 3), the filter is initially set.

Next, at step SD12, the volume modulation signal obtained by adding the LFO waveform read according to the current phase value of the register LPH [part] and the volume waveform for envelope control output from the EG 73 (see FIG. 3) is added to the amplifier 79. After performing the initial setting of the amplifier supplied to (see FIG. 3), the present process is terminated.

  As described above, in the note-on process, the sound channel newly assigned to be generated according to the key depression is set to the sounding state, and if the LFO waveform of the timbre part to which the sound channel is assigned is stopped, The random number generated based on the random function is set to the initial phase of the LFO waveform and output is resumed.

  As described above, according to the present embodiment, after all the sound generations are muted, if the sound generation instruction by the key depression does not occur during the checkpoint period (operation stop preparation state) for one cycle of the LFO waveform, Then, the output of the LFO waveform is stopped, and when a sound generation instruction is generated by pressing a key while the LFO waveform is stopped, the generation of the LFO waveform is resumed with a random phase. As a result, for example, as shown in FIG. 11, the disadvantage of the conventional example in which the low-frequency oscillator is operated only during sound generation for the purpose of reducing the load on the sound source, that is, the phase of the LFO waveform is reset to the head every time sound generation is started. It is possible to eliminate the adverse effect of the modulation waveform giving a monotonous modulation effect, and to reduce the load on the sound source while maintaining the unique modulation effect derived from the long-period LFO waveform.

  In the present embodiment, after all the sound generations are muted, during the checkpoint period (operation stop preparation state) for one cycle of the LFO waveform, if no sound generation instruction is generated by pressing the key, the LFO waveform is stopped. However, the present invention is not limited to this, and if all the sound generation is muted and no sound generation instruction is issued by pressing the key, the LFO waveform output is stopped. It does not matter as a mode of transition to the stop state. In this embodiment, the pitch, the cut-off frequency of the filter, and the volume have been described as examples of LFO modulation targets. However, the above-described effects can be obtained even with other parameters related to timbre. In addition, in this embodiment, the LFO is prepared for each timbre parameter. However, a plurality of vibrato, filter, and amplifier may be prepared for each part. Also has the above-mentioned effects.

It is a block diagram which shows the structure of the electronic musical instrument 10 which is one Embodiment of this invention. 3 is a memory map showing a configuration of main registers provided in a RAM 6; 3 is a block diagram showing a configuration of a sound source 7. FIG. It is a figure for demonstrating the relationship between the sound generation channel (voice) with which the sound source 7 is equipped, and a timbre part. It is a figure which shows the outline | summary of operation | movement of LFO80. It is a flowchart which shows operation | movement of the main routine which CPU4 performs. It is a flowchart which shows the operation | movement of the envelope process which CPU4 performs. It is a flowchart which shows the operation | movement of the LFO process which CPU4 performs. It is a flowchart which shows the operation | movement of the note-on process which CPU4 performs. It is a figure for demonstrating a prior art. It is a figure for demonstrating a prior art.

Explanation of symbols

1 Keyboard 2 MIDI Interface 3 Switch 4 CPU
5 ROM
6 RAM
7 Sound source 8 D / A converter 9 Sound system

Claims (5)

LFO waveform generating means for generating an LFO waveform;
Storage means for storing state information indicating whether the state of the LFO waveform is a stop state, a normal operation state, or an operation stop preparation state;
State determination means for determining whether the state information stored in the storage means is a normal operation state or an operation stop preparation state at a predetermined period;
When the state determination means determines that the state information is in a normal operating state, a sound generation detection means for detecting the presence or absence of a sound generated by the LFO waveform generated by the LFO waveform generation means;
Control means for setting the state information stored in the storage means to an operation stop ready state when the sound detection means detects that the musical sound is not sounded;
When the state determination means determines that the state information is in the operation stop preparation state, the stored state information is set to the stop state, and the LFO waveform generation means is instructed to stop generating the LFO waveform. Stop instruction means;
Resuming instruction means for instructing the LFO waveform generating means to resume the output of the LFO waveform when the state information stored in the storage means indicates a stopped state and when the musical sound is instructed to be generated. A low-frequency oscillation device. The state determination unit determines whether the state information stored in the storage unit is a normal operation state or an operation stop preparation state every time the LFO waveform generation unit generates an LFO waveform for one cycle. 2. The low-frequency oscillation device according to claim 1, wherein   2. The low-frequency oscillation device according to claim 1, wherein the restart instruction means sets a random number generated based on a random function to an initial phase of the LFO waveform and instructs the LFO waveform generation means to restart output.   2. The low frequency oscillator according to claim 1, wherein the LFO waveform generated by the LFO waveform generating means modulates at least one of a pitch, tone color and volume of a musical tone to be generated. In a computer used as a low-frequency oscillation device having storage means for storing state information indicating whether the LFO waveform is in a stopped state, a normal operating state, or an operation stop ready state,
LFO waveform generation processing for generating the LFO waveform;
A state determination process for determining whether the state information stored in the storage means is a normal operation state or an operation stop preparation state at a predetermined period;
When the state determination process determines that the state information is in a normal operation state, a sound generation detection process for detecting the presence or absence of a tone generated by the LFO waveform generated by the LFO waveform generation process;
A control process for setting the state information stored in the storage means to an operation stop ready state when it is detected by the sound generation detection process that there is no sound generation of the musical sound;
If it is determined by the state determination process that the state information is in an operation stop preparation state, the stored state information is set to a stop state, and the LFO waveform generation process is instructed to stop generating an LFO waveform. Stop instruction processing;
When the state information stored in the storage means indicates a stopped state and when the musical tone is instructed to be played, a restart instruction process for instructing the LFO waveform generation process to resume the output of the LFO waveform is performed on the computer. A low-frequency oscillation processing program that is executed by

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