JP2606684B2 - Waveform processing device based on frequency modulation tone synthesis principle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of processing a supplied reference waveform signal based on a frequency modulation principle to generate a tone signal having a rich timbre including many harmonic components. The present invention relates to a waveform processing apparatus based on the principle of frequency modulation tone synthesis.

[Conventional technology]

2. Description of the Related Art Conventionally, as a tone generator for an electronic musical instrument or the like, a tone signal generator of a frequency modulation system in which a sine waveform signal of a predetermined frequency is frequency-modulated to obtain a tone signal of a rich tone containing many harmonic components. It has been known. For example, the apparatus disclosed in Japanese Patent Publication No. 54-33525 corresponds to this.

On the other hand, as shown in JP-A-58-108583 and JP-A-58-50595, an input tone signal is delayed by using a delay RAM or a shift register, and the delay time is set to an LFO.
There is also known an effect device that modulates with a predetermined low-frequency signal generated by a (low-frequency oscillator) or the like to add a multi-series effect such as a vibrato effect or a chorus or ensemble to an input musical sound.

[Problems to be solved by the invention]

However, in the tone synthesis technique according to the conventional frequency modulation method as shown in the above-mentioned Japanese Patent Publication No. 54-33525, the tone synthesis by frequency modulation is performed unless the waveform reading system has a frequency modulation mechanism. There is a disadvantage that it cannot be done. That is, in this kind of tone synthesis technology, it is essential to introduce a modulation signal into the phase data of the carrier signal, so unless a device specifically configured as a tone synthesis device according to the frequency modulation method is used from the beginning, Music synthesis by frequency modulation could not be performed.

The present invention has been made in view of the above points, and even when a tone generating means for generating a tone signal does not have a frequency modulation mechanism in a waveform reading system, the tone generating means has finished generating the tone signal. It is an object of the present invention to introduce and process a tone signal so that tone processing can be performed in accordance with the principle of frequency modulated tone synthesis.

By the way, the above-mentioned Japanese Patent Application Laid-Open No. 58-108583 and
The effect device described in Japanese Patent No. 50595 has an inherent principle of frequency modulation using delay means. However, in these effect devices, the frequency of the LFO is simply set to a low frequency (a band below the audible band of 0.1 to several Hz) irrespective of the frequency of the input tone signal. This is this LF
If the frequency of O is lower than the audible band, the effect due to it is within the range of the multi-sequence effect obtained by changing the pitch over time, but if the frequency extends to the audible band. For example, the effect is that the pitch no longer changes over time, and the waveform is deformed to give a musical tone of another timbre. Therefore, in these effect devices, the frequency of the LFO must be lower than the audible band.

By the way, Japanese Patent Application Laid-Open No. 50-12606 discloses that it is possible to perform tone processing from pitch processing by raising the frequency of an LFO for vibrato or the like to the audible band. Imagine creating a device for tone processing by increasing the modulation frequency of the effect device described in JP-A-58-108583 and JP-A-58-50595 to the audible band.

However, in such a device, the modulation frequency is in the audible band, but since the frequency is independent of the frequency of the tone signal to be modulated, the harmonic added to the processed tone is always an integral multiple. In addition, the relationship between the fundamental frequency and the overtone varies depending on the frequency of the tone signal to be modulated, so that only a tone having a very limited content can be synthesized.

Further, determining the frequency of the modulated wave by the LFO or the like based on the pitch frequency of the tone signal to be modulated,
That is, consider a case in which the configuration is devised so as to be proportional to the frequency of the fundamental vibration of the tone to be modulated. In that case, a circuit that detects the fundamental frequency of the modulated tone signal and a circuit that controls the oscillation frequency of the modulated signal by introducing the pitch designation information of the tone generated from the source of the tone signal, etc., are required. However, there is a problem that the configuration is complicated.

The present invention has been devised in view of this point, and even when the tone reading means for generating a tone signal does not have a frequency modulation mechanism in the waveform reading system, the tone generating means is not used. The purpose of the present invention is to introduce and process the generated tone signal so that tone processing can be performed in accordance with the principle of frequency modulated tone synthesis. It is also an object of the present invention to perform tone processing that realizes a musically preferable overtone relationship without causing a non-integer multiple relationship that varies depending on the tone frequency of the completed tone signal.

[Means for solving the problem]

A waveform processing apparatus based on the principle of frequency modulation musical tone synthesis according to the present invention is a means for receiving waveform data relating to each sample point amplitude value of a reference waveform signal generated at a desired frequency in an audible band. Delay means for sequentially inputting and delaying output, modulation signal generation means for generating a modulation signal based on waveform data supplied to the delay means or waveform data delayed by the delay means, and time change of the modulation signal Control means for modulating the delay time of the waveform data output from the delay means in accordance with the above, and generating a tone signal having characteristics obtained by tone-modulating the reference waveform signal by frequency modulation. is there.

[Action]

Waveform data relating to the amplitude value of each sample point of the reference waveform signal generated at a desired frequency in the audible band is supplied to the delay means, and is output after being sequentially delayed. The modulation signal generation means generates a modulation signal based on the waveform data supplied to the delay means or the waveform data delayed by the delay means. The delay time of the waveform data output from the delay means is modulated by the control means in accordance with the time change of the modulation signal. Thereby, a signal obtained by frequency-modulating a reference waveform signal having an audible band frequency by the reference waveform signal itself or a signal obtained by appropriately modulating the reference waveform signal can be obtained at the delay output of the delay unit. Become.

Therefore, even if a reference waveform signal is generated from a tone generator (sound source) not based on the frequency modulation tone synthesis principle,
This is introduced into the delay means of the present apparatus, and the modulation of the delay time is performed by the reference waveform signal itself or by a signal obtained by appropriately modulating the reference waveform signal. Processing). That is, there is an excellent effect that a waveform processing (tone processing) based on the principle of frequency modulation tone synthesis can be performed on a reference waveform signal generated from an arbitrary sound source.

Moreover, in this case, the modulation signal is based on the reference waveform signal itself or a signal obtained by delay-modulating the reference waveform signal by the delay means, so that no special modulation function generation table or the like is required as the modulation signal generation means. This has the advantage that the configuration can be simplified.

The relationship between the carrier signal and the modulation signal in frequency modulation is that the reference waveform signal is used as the carrier signal, and the reference waveform signal itself or a signal obtained by appropriately delay-modulating the reference waveform signal is used as the modulation signal. Therefore, the two frequencies match or are in harmony, and the phase and the amplitude are appropriately different or proportionally changed. Basically, they have an overtone relationship that is an integral multiple of the fundamental frequency of the reference waveform signal. A tone waveform signal can be obtained, and waveform processing (tone processing) can be performed in a direction of increasing harmonics so as to include abundant harmonics, and waveform processing (tone processing) preferable as a musical tone is performed. Can do that.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a phase signal generating circuit 1 receives pitch designation information KC representing the pitch of a musical tone signal to be generated, and generates a tone represented by the pitch designation information KC. Phase designating signal x that changes sequentially at a speed corresponding to high
Is output. The reference waveform generation circuit 2 stores, for example, each sample point amplitude value of a sine waveform as a reference waveform signal over one period, and receives the phase designation signal x and designates the phase designation signal x. The sampled point amplitude value of the sine wave phase is read out and output. As a result, the reference waveform generating circuit 2 sequentially generates waveform data representing the amplitude of each sample point of the reference waveform signal (sine waveform) at a speed corresponding to the pitch of the musical tone signal to be generated. The waveform data of the reference waveform signal generated in this way is supplied to the shift register 3.

The shift register 3 has a storage position of n (≧ 2) stages.
ST ₁ has a ～ST _n, the waveform data of the reference waveform signal from the reference waveform generator circuit 2 is input, the input-side storage position ST ₁ by a clock pulse φ synchronized with the waveform data in the phase designation signal x sequentially storing the sample point units toward the output-side storage position ST _n from.

Therefore, if one cycle time of the clock pulse φ is represented by t, the waveform data output from the reference waveform generation circuit 2 from the m-th (m = 1 to n) -th storage position ST _m mt time before the current time t ₀ is obtained. Is obtained.

In this way, the storage locations ST _{1 to} S ₁ of the shift register 3
The waveform data at each sample point of the reference waveform signal obtained from T _n is equal to the number of inputs A _{1 as the} number of storage positions in the shift register 3.
They are respectively supplied to the input A ₁ to A _n of the selector 4 with to A _n.

On the other hand, the waveform data obtained from the final storage location of the shift register 3 ST _n nt time the previous sample point is input to the multiplier 50 of the modulation signal generation circuit 5.

The modulation signal generation circuit 5 generates a modulation signal for frequency-modulating the reference waveform signal, and generates a modulation coefficient I for controlling the modulation depth and inputs the modulation coefficient I to the multiplier 50. 51, and a decoder 52 for decoding output data of the multiplier 50.

When the shift register 3 is supplied with the waveform data of the reference waveform signal before nt time to the modulation signal generation circuit 5 having such a configuration, the waveform data and the modulation coefficient I generated by the modulation coefficient generation circuit 51 are output. Is multiplied by the multiplier 50. Then, the result of the multiplication is input to the decoder 52, where it is coded.

The decoded output of the decoder 52 is
It is supplied to the control terminal SC of the selector 4 as the select control signal for selecting one of the waveform data of the sample points of the respective input reference waveform signal to ₁ to A _n.

Thus, for example, the output data of the multiplier 50 is the waveform data of the input A _n selects and outputs the selector 4 when the maximum value, when the minimum value of the selector 4 in relation to selectively output the waveform data of the input A ₁ If you set the selection operation, the waveform data of nt time the previous sample point input an in selector 4 when indicating the maximum amplitude value and the input a ₁ when indicating the minimum amplitude value, further the maximum amplitude value and the minimum amplitude value input a ₂ ~A _n-1 according to the intermediate value when an intermediate value is selected each of the, respective inputs a ₁
One of the sample point waveform data from 1 · t to nt time input to 〜A _n is selectively output.

That is, different sample point waveform data is selectively output from the selector 4 according to the magnitude of the amplitude value of the sample point waveform data n · t time ago. In other words, the selector 4 selectively outputs a signal obtained by frequency-modulating the reference waveform signal according to its own amplitude value n · t times before.

Therefore, by appropriately setting the modulation coefficient I, the tone signal DGS in a state where the reference waveform signal is frequency-modulated can be obtained from the selector 4.

In this case, if a frequency changing circuit for increasing the frequency (sampling rate) of the reference waveform signal to an integral multiple or a fraction of an integer is inserted on the input side or the output side of the multiplier 50, further different frequency modulation is performed and the frequency is further enhanced. It is possible to obtain a musical tone signal DGS having an appropriate tone.

FIG. 2 is a block diagram showing still another embodiment of the present invention. The difference from the embodiment of FIG. 1 is that the waveform data input to the multiplier 50 of the modulation signal generating circuit 5 is output from the output side of the selector 4. It is to take out.

According to this configuration, the first out for the value of the output data of the selector 4 is zero, the selector 4 selectively outputs the waveform data input of the input A ₁ to A _n for example A _1. When the first waveform data is selected and output, the amplitude value is multiplied by the modulation coefficient I and input to the decoder 52, so that the decoder 52 sends out a new decoded output, and thereby another new output is output. The waveform data at the appropriate sample point is selectively output from the selector 4. Thereafter, the operation of selecting and outputting the waveform data of the next new sample point is repeated in accordance with the amplitude value of the waveform data of the sample point that has been selected and output most recently. That is, the next tone signal DGS is used according to the current sample point amplitude value of the tone signal DGS.
The operation of determining the sample point amplitude value to be generated as GS is repeated. As a result, a tone signal DGS having a tone similar to that of the feedback FM modulation method can be obtained.

FIG. 3 is a block diagram showing still another embodiment of the present invention. This embodiment is basically different from the previous embodiment in that a digital memory (RAM) 6 is used as means for storing each sample point waveform data of the reference waveform signal, and the read address signal AR is modulated. It was done.

In FIG. 3, the sample point waveform data of the reference waveform signal output from the reference waveform generation circuit 2 is a write instruction signal.
The data is written to the digital memory 6 in the write mode in which the SW is “1”. The write address in this case is specified by the write address signal AW output from the address counter 7 that counts the clock pulse φ. The write address signal AW is selected by the selector 8 when the select control signal SS for the selector 8 is "1", and is given to the digital memory 6.

Thereby, the digital memory 6 sequentially stores the sample point waveform data of the reference waveform signal generated from the reference waveform generation circuit 2 in units of sample points. In the read mode of "1", the read operation is performed according to the read address signal AR provided from the arithmetic circuit 9 via the selector 8. This read address signal AR is formed as follows in order to obtain a frequency-modulated tone signal DGS.

That is, the multiplier 50 multiplies the sample point waveform data of the reference waveform signal generated from the reference waveform generation circuit 2 by the modulation coefficient I generated by the modulation coefficient generation circuit 51 in the multiplier 50, so that the time change of the reference waveform signal is obtained. A modulated signal MD that changes correspondingly is formed, and this modulated signal MD is input to a first addition input of the arithmetic circuit 9. Further, the second
The write address signal AW indicating a continuous change output from the address counter 7 is input to the addition input of the, and the offset address information AOF generated from the offset address information generator 55 is input to the subtraction input. AR = AW-AOF + MD (1) A read address signal AR shown by the following formula is formed.

Here, the offset address information AOF is given as a constant corresponding to a desired modulation depth.

This allows the modulation signal M to be centered on an address (AW-AOF) separated from the address indicated by the write address signal AW by the address indicated by the offset address information AOF.
A read address signal AR whose address value increases or decreases according to the time change of D is formed.

Therefore, let T be the sampling period of the reference waveform signal,
If the write instruction signal SW and the select control signal SS are set to "1" in the first half of the cycle T, and these signals SW and SS are set to "0" and the read instruction signal SR is set to "1" in the second half, the cycle T
In the first half, the write address signal AW is selected by the selector 8, and in the second half, the read address signal AR is selected by the selector 8 and supplied as an address signal of the digital memory 6. Therefore, in the first half of the cycle T, the sample point waveform data of the reference waveform signal generated at the current time t is written into the memory 6 according to the write address signal AW. On the other hand, in the latter half, the sampling point waveform data T · (AW−AOF + MD) time before the current time t is read from the memory 6 in accordance with the read address signal AR.

As a result, a tone signal DGS frequency-modulated by the modulation signal MD can be obtained from the digital memory 6.

In the above-described embodiment, the reference waveform signal is a sine waveform. However, the reference waveform signal is not limited to the sine waveform, and may have any waveform shape. In this case, the reference waveform signal may be generated by reading out a waveform memory storing a plurality of cycles of waveforms having sequentially different waveform shapes. Further, the reference waveform generating circuit is not limited to the one that generates the reference waveform signal by reading the waveform memory, but generates the reference waveform signal by performing a predetermined waveform forming operation in accordance with the phase designation signal x. Or any other sound source.

Also, in the embodiment of FIGS. 1 and 2, the modulation coefficient is input to the multiplier 50 to control the modulation depth. The modulation depth may be controlled.

Further, in the above-described embodiment, only the case where a single tone (only one series) tone signal is generated has been described.
The present invention can be similarly applied to the case of generating a multiple tone (multiple series) tone signal.

Further, the tone signal GDS obtained by the above-described embodiment
May be used as a new reference waveform signal, and the reference waveform signal may be frequency-modulated again in the same manner as in the above-described embodiment to generate a tone signal containing more harmonic components.

Further, the tone signal generating apparatus according to the present invention can be used not only for generating tone signals corresponding to scale sounds but also for generating various tone signals corresponding to rhythm sounds, human voices, and the like.

〔The invention's effect〕

Even a reference waveform signal generated from a tone generator (sound source) not based on the frequency modulation tone synthesis principle is introduced into the delay means, and the reference waveform signal itself or the reference waveform signal is appropriately modulated. Since the modulation of the delay time is controlled by the signal, the waveform processing (tone processing) based on the frequency modulation tone synthesis principle can be performed. That is, there is an excellent effect that a waveform processing (tone processing) based on the principle of frequency modulation tone synthesis can be performed on a reference waveform signal generated from an arbitrary sound source.

Moreover, in this case, the modulation signal is based on the reference waveform signal itself or a signal obtained by delay-modulating the reference waveform signal by the delay means, so that no special modulation function generation table or the like is required as the modulation signal generation means. This has the advantage that the configuration can be simplified.

The relationship between the carrier signal and the modulation signal in frequency modulation is that the reference waveform signal is used as the carrier signal, and the reference waveform signal itself or a signal obtained by appropriately delay-modulating the reference waveform signal is used as the modulation signal. Therefore, there is a relationship in which the two frequencies match or match and the phase and amplitude are appropriately different or proportionally changed, and basically have an overtone relationship of an integral multiple of the fundamental frequency of the reference waveform signal. A tone waveform signal can be obtained, and waveform processing (tone processing) can be performed in a direction of increasing harmonics so as to include abundant harmonics, and waveform processing (tone processing) preferable as a musical tone is performed. It also has an excellent effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. 3 is a block diagram showing still another embodiment of the present invention. 1... Phase signal generating circuit, 2... Reference waveform generating circuit, 3
... shift register, 4 ... selector, 5 ... modulation signal generation circuit, 6 ... digital memory, 9 ... arithmetic circuit,
51: Modulation coefficient generation circuit, 52: Decoder.

Claims (8)

(57) [Claims] 1. A means for receiving waveform data for each sample point amplitude value of a reference waveform signal generated at a desired frequency in an audible band, the delay means for sequentially inputting the waveform data and delaying the input. Modulation signal generating means for generating a modulation signal based on the waveform data supplied to the delay means or the waveform data delayed by the delay means; and waveform data output from the delay means in accordance with a time change of the modulation signal. Control means for modulating the delay time of the reference waveform signal, and generating a tone signal having characteristics obtained by tone-modulating the reference waveform signal by frequency modulation. 2. A waveform processing apparatus according to claim 1, wherein said reference waveform signal is generated by repeatedly reading out one cycle of waveform data. 3. The waveform processing apparatus according to claim 1, wherein the reference waveform signal is a waveform signal having a plurality of periods whose waveform shapes are sequentially different in time. 4. The delay means has a readable and writable storage means for sequentially writing and storing the waveform data, and a delayed output is generated by delaying and reading out the waveform data stored in the storage means. 2. The waveform according to claim 1, wherein the control unit modulates a delay time of the waveform data by performing modulation control on reading of the storage unit in accordance with the modulation signal. Processing equipment. 5. The delay means comprises: a write means for sequentially writing the waveform data to the storage means by a write address signal which changes according to the predetermined write speed; and a write address corresponding to a time for delaying the waveform data. Reading means for reading the waveform data from the storage means by a read address signal indicating a value different from the signal. The control means performs an operation of modulating the read address signal in accordance with the modulation signal. 5. The waveform processing apparatus according to claim 4, wherein the reading of said storage means is modulation-controlled in accordance with said modulation signal. 6. A shift register having a plurality of storage stages for sequentially shifting the contents of each of the storage stages in synchronization with the desired speed, and selecting control of each of the storage stages of the shift register. A selector for selecting and outputting the waveform data of the storage stage corresponding to the signal, wherein the control means changes the selection control signal in accordance with the modulation signal to thereby delay the waveform data. 2. The waveform processing apparatus according to claim 1, wherein the apparatus modulates time. 7. The frequency modulation tone synthesis principle according to claim 1, wherein said modulation signal generation means generates a modulation signal based on waveform data delayed by a predetermined time by said delay means. Wave processing equipment. 8. The modulation signal generation means for generating a modulation signal based on waveform data delayed and output from the delay means with a delay time modulated according to control by the control means. A waveform processing apparatus based on the frequency modulation musical tone synthesis principle according to claim 1.