JPH0525117B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a musical tone synthesis method for synthesizing musical tone signals using modulation calculations such as frequency modulation calculations or amplitude modulation calculations, and in particular, a method that can control a relatively large number of frequency components with simple calculations. Regarding what I did. [Prior art] Previously, Tokuko No. 54-33525, Tokoku No. 54-7570,
As disclosed in Japanese Patent Publication No. 58-29519, a technique is known in which a musical tone signal having a desired overtone structure is synthesized by frequency modulation calculation or amplitude modulation calculation in the audible frequency range. [Problems to be Solved by the Invention] However, in all of the above-mentioned conventional methods, a simple mononomial modulation calculation is not sufficient to synthesize a musical tone with a satisfactory tone that has sufficient overtone components. However, complex modulation operations using multiple or polynomial equations had to be performed. As a result, the configuration of the arithmetic circuit becomes complicated and large, and in the case of a method in which each arithmetic term is computed in a time-sharing manner, the control clock has to be made faster, which tends to increase costs. As a method of synthesizing musical tones containing many overtone components using relatively simple calculations, as shown in the above-mentioned Japanese Patent Publication No. 54-7570, a waveform having many frequency components is synthesized in advance as a modulated wave or A method of using it as a modulated wave has been considered, but since the waveforms that can be used for calculations are limited to those stored in the waveform memory, there is a limit to the tones that can be synthesized. [Means for Solving the Problems] A musical tone synthesis method according to the present invention is a musical tone synthesis method for synthesizing a musical tone signal based on a predetermined modulation signal calculation using a modulation signal and a modulated signal. generating phase data in order to generate at least one of the signals, reading out the waveform from a storage means storing a predetermined waveform based on the phase data, and determining a predetermined phase of the phase data based on the phase data; The method is characterized by identifying an interval, inverting the polarity of a portion of the read waveform corresponding to this phase interval, and using the waveform with this predetermined interval inverted for the modulation calculation. be. [Operation] Based on the phase data for generating the modulated signal or the modulated signal, a predetermined phase section of the phase data is specified. On the other hand, the waveform of the modulated signal or the modulated signal is read out from the storage means based on this phase data, and the polarity of the read out waveform is inverted in the specified predetermined phase interval.
Therefore, due to the inversion process in this predetermined phase interval, the shape of the waveform changes sharply, and changes into a waveform that includes many harmonic components. Furthermore, if there are waveform portions of both positive and negative polarities in this predetermined phase interval, these portions will be inverted to opposite polarities, making it possible to make the waveform obtained by conversion even more complex. This makes it possible to control many harmonic components and create a variety of tones without having to perform complex modulation calculations such as polynomials or storing many types of complex waveforms in the waveform storage means. Control can be easily realized using an extremely simple configuration of waveform inversion control in a specific phase section of phase data. [Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention in a frequency modulation (hereinafter abbreviated as FM) calculation type musical tone synthesis method, which can be roughly divided into a modulated wave function generator 10 and a modulated wave function generator 10. It includes a function generating section 20 and an adder 30 for performing phase modulation of a modulated wave, that is, a carrier wave. In the modulated wave function generator 10,
Read the sine waveform data sinωmt from the sine wave table 11 according to the modulated wave phase angle data ωmt,
This is multiplied by modulation index data I(t) in a multiplier 12 and output as modulated wave data. In the adder 30, the multiplier 12
The modulated wave data I(t)·sinωmt outputted from the carrier wave is added to perform phase modulation of the carrier wave. The modulated wave function generator 20 generates phase angle data θ of the phase-modulated carrier wave output from the adder 30.
A predetermined modulated wave function is generated according to (θ=ωct+I(t)·sinωmt), and a musical tone signal G is output based on this modulated wave function. In the embodiment shown in FIG. 1, the present invention is applied to the modulated wave function generating section 20. That is, the modulated wave function generation section 20 includes a sine wave table 21, a code control circuit 22, and a code conversion circuit 2.
3 and a multiplier 24, and the sine wave table 21 receives carrier wave phase angle data θ from an adder 30.
When is input as an address signal, sine waveform data sin θ is read out in accordance with this phase angle data θ. In this case, the sine waveform data sin θ has a sign bit. This sine waveform data sinθ is then supplied to the code conversion circuit 23. On the other hand, the phase angle data θ is also supplied to the code control circuit 22. This code control circuit 22 generates a code control signal SC for controlling the sign of the sine waveform data sin θ read out from the sine wave table 21 in a specific phase section in one period of the phase angle data θ.
Output. The sign control signal SC becomes "1" when changing the sign of the sine waveform data sin θ, and becomes "0" when the sign is not changed. The specific phase section in which the code control signal SC is "1" is changed in accordance with the timbre selection signal TC. This code control signal SC is given to the code conversion circuit 23. As a result, the sign of the sine waveform data sinθ read from the sine table 21 is changed to the opposite sign while the code control signal SC is “1”. To simplify the explanation, if the phase angle data θ is simply increasing data (θ=ωct) as shown in FIG. For example, a code control signal SC as shown in FIG. 2b is output in response to the timbre selection signal TC while changing from 0 to 2π. As a result, the code conversion circuit 23 outputs sine waveform data whose polarity is inverted in a specific phase section of one period of the sine wave (the section where the signal SC is "1"), as shown in FIG. 2c. That is, the signal SC
is set to "1" every π of the phase angle data θ, the polarity of the sine waveform data sin θ read from the sine wave table 21 is inverted every π, and is changed to sine waveform data having only positive values. In addition, Fig. 2c
The waveform shown in FIG. 3 has a frequency spectrum as shown in FIG. In this way, the sine waveform data sinθ with the positive polarity of the specific phase section changed is supplied to the multiplier 24, where it is multiplied by the amplitude coefficient data A(t) to control the amplitude setting. is performed and output as a musical tone signal G. Therefore, when the control signal SC output from the code control circuit 22 is changed as shown in FIG. 2d in accordance with the timbre selection signal TC, the sine waveform data output from the code conversion circuit 23 is changed to It will look like the one shown below. The musical tone signal G outputted from the modulated wave function generating section 20 in this manner contains a large number of harmonic components, as is clear from the waveform shapes shown in FIGS. 2c and 2e. As a result, a musical tone signal G containing many harmonic components can be obtained with a simple configuration. Incidentally, the parameters ωmt, I(t), ωct, TC, and A(t) used in this embodiment are given, for example, from a circuit as shown in FIG. Fourth
In the figure, a keyboard circuit 40 detects keys pressed on the keyboard of an electronic musical instrument and outputs key press data. The phase data generation circuit 41 generates modulated wave phase angle data ωmt and carrier wave phase angle data ωct that change at a cycle corresponding to the pitch of the pressed key in accordance with key press data provided from the keyboard circuit 40. On the other hand, the envelope generator 42 is connected to the keyboard circuit 4
Key-on signal generated when a key is pressed from 0
Modulation index data I(t) and amplitude coefficient data A(t) which sequentially change over time are generated in response to KON. These phase data generation circuit 41 and envelope generator 42 are given a timbre selection signal TC from a timbre selection circuit 43, and the frequency ratio of ωct and ωmt and the waveform shape of the time function of I(t) and A(t) are Controlled according to the selected tone. In the embodiment shown in FIG. 1, the polarity of the sine waveform data sinθ output from the sine wave table 21 is changed using the sign conversion circuit 23; may be configured such that the signal has only an absolute value without a sign, and the sign control circuit 22 directly outputs a bit signal indicating a positive or negative sign. In this way, the code conversion circuit 23 becomes unnecessary. Further, in this case, the sine wave table 21 may store only a half cycle of the sine waveform. Further, in the above embodiment, the modulated wave function generating section 20
Although the case where this invention is applied to is shown, it can be similarly applied to the modulated wave function generating section 10.
That is, in FIG. 1, the code conversion circuit 23 is provided on the output side of the sine wave table 11, and the phase angle data θ input to the code control circuit 22 is replaced with the phase angle data ωmt of the modulated wave. In this case, the present invention may be applied to both the modulated wave function generating section 10 and the modulated wave function generating section 20. In addition, in FIG. 1, the sine wave table 11
If the output waveform data is fed back to the input side as shown by the broken line and the phase angle data ωmt is modulated by this output waveform data, a musical tone signal G having more complex harmonic components can be obtained. FIG. 5 is a block diagram showing an embodiment of the present invention in an amplitude modulation (hereinafter abbreviated as AM) calculation type musical tone synthesis method, in which the present invention is applied to a modulated wave function generating section 50. That is, the modulated wave function generation section 50 is composed of a sine wave table 51, a code control circuit 52, and a code conversion circuit 53,
When carrier wave phase angle data ωct is input as an address signal to the sine wave table 51, sine waveform data sinωct corresponding to this phase angle data ωct is read out and supplied to the code conversion circuit 53. On the other hand, the phase angle data ωct is supplied to the code control circuit 52 together with the timbre selection signal TC. As a result, the code control circuit 52 generates a code control signal SC that is "1" only in a specific phase section corresponding to the timbre selection signal TC in one period of the phase angle data ωct,
This control signal SC is supplied to the code conversion circuit 53. As a result, the polarity of data in a specific phase section of the sine waveform data sinωct read out from the sine wave table 51 as a carrier wave, that is, a modulated wave function, is inverted, resulting in a waveform shape similar to that shown in FIGS. 2b and 2c. The modulated wave function will be output. On the other hand, a modulated wave function generator 60 that modulates this modulated wave function includes a sine wave table 61, a multiplier 62
and a cosine wave table 63, and when modulated wave phase angle data ωmt is input to the sine table 61 as an address signal, sine waveform data sinωmt corresponding to the phase angle data ωmt is read from the sine wave table 61. . This sine waveform data sinωmt is converted into modulation index data I(t) by a multiplier 62.
After being multiplied by , it is supplied to the cosine wave table 63 as an address signal. As a result, cosine waveform data cos {I(t)・sinωmt} is obtained from the cosine wave table 63.
is read out. This cosine waveform data cos {I(t)・
sinωmt} is supplied to the multiplier 70 as a modulated wave function, and is multiplied by the modulated wave function to perform amplitude modulation calculation. The output of this multiplier 70 is
The signal is supplied to a multiplier 80, multiplied by amplitude coefficient data A(t), and outputted as a post-tone signal G whose amplitude is controlled. Therefore, in this embodiment as well, since the modulated wave function itself already contains many harmonic components, the musical tone signal G that is finally obtained also contains many harmonic components. In this embodiment as well, the polarity of the modulated wave function is changed by adding a sign bit output from the sign control circuit 52 to the sine waveform data of only the absolute value read from the sine waveform table 51. You can do it like this. Further, the present invention may be applied only to the modulated wave function generating section 60, or may be applied to both of the modulated wave function generating sections 50. By the way, the operator unit OPU for generating a modulated wave function or a modulated wave function as shown in FIG.
By configuring this, it is possible to generate a musical tone signal with a waveform shape that changes in a more complicated manner. That is, by inputting the phase angle data x to the shifter 90 and shifting the phase angle data x to the upper bit side or the lower bit side by the shift amount specified by the phase shift data ASFT given from the waveform control section 91, one cycle is completed. is multiplied by k (where k = 2±j, j is the shift amount, +j indicates a shift to the upper bit side, and -j indicates a shift to the lower bit side. This ±j is determined by the data ASFT. The phase angle data kx specified by the command is extracted. next,
This phase angle data kx is inputted as an address signal to a waveform table 92 storing sine waveform data as a logarithm value logsinx, and this waveform table 92
Read the logsinkx sine waveform data from. Next, this sine waveform data logsinkx is input to the shifter 93 and shifted to the upper bit side or lower bit side by the shift amount specified by the waveform shift data DSFT given from the waveform control section 91. waveform data m/
Change to logsinkx. Here, m is m=22±i
, +i indicates a shift to the upper bit side, -
i indicates a shift to the lower bit side. This ±i is indicated by data DSFT. Next, this waveform data m·logsinkx is input to a logarithmic linear converter 94 and converted into natural number waveform data (sinkx) ^m . That is, the shift amount ±i in the shifter 93
For example, when i = 1 (when the output of the waveform table 92 is shifted by 1 bit to the upper bit side or the lower bit side), (sinkx) ² or √
You can get sinkx waveform data. Next, select this waveform data (sinkx) ^m using selector 9.
5 to the gate 96, and the waveform controller 91
The output is performed only during a specific phase period in which the control signal given from the control signal is "1". Furthermore, code data SD indicating positive and negative polarity given from the waveform control unit 91 to the waveform data (sinkx) ^m of this specific phase section
is added and output externally. Here, phase shift data ASFT, waveform shift data DSFT, select control signal of selector 95
SEL, the control signal, and the code data SD are controlled differently depending on the timbre selection signal TC.
Then, for a specific selected tone, the phase angle data kx outputted from the shifter 90 is selected by the selector 95 and outputted via the gate 96. Therefore, the waveform shift amount ±i indicated by DSFT
is +1, the phase shift amount ±j specified by ASFT is 1, and the phase interval where the control signal is “0” is π.
~2π, the selector 95 is set to the A input selection state (a state in which the output of the log-linear converter 95 is selected and output), and the code data SD is positive from 0 to π/2, and from π/2 to
When π is negative, sin2x ² as shown in Figure 7a
waveform data is obtained in the phase interval of 0 to π. Also, data output from the waveform control section 91
By setting ASFT etc. as shown in Table 1 below, waveform data having a waveform shape as shown in FIG. 7b can be obtained.

[Table] Further, by setting the data ASFT etc. as shown in Table 2, triangular waveform data as shown in FIG. 7c can be obtained.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a predetermined phase interval of the phase data is specified based on the phase data for generating a modulation signal or a modulated signal, and in this predetermined phase interval, The polarity of the waveform of the modulating signal or modulated signal read out from the storage means is inverted based on the phase data, and the inverted waveform is used for modulation calculations. Therefore, the shape of the waveform changes sharply, and the waveform can be transformed into a waveform containing many harmonic components. Moreover, if there are waveform portions of both positive and negative polarities in this predetermined phase interval, they will be inverted with respect to each other, making it possible to make the waveform obtained by conversion even more complex. This makes it possible to control many harmonic components and create a variety of tones without having to perform complex modulation calculations such as polynomials or storing many types of complex waveforms in the waveform storage means. This has an excellent effect in that control can be easily realized using an extremely simple configuration of waveform inversion control in a specific phase section of phase data. This not only makes it possible to reduce the size and cost of the circuit, but also has the effect that musical tone signals of various tones can be synthesized by simple control.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention in an FM calculation type musical tone synthesis method, Fig. 2 is a diagram showing an example of the output waveform of each part in Fig. 1, and Fig. 3 is shown in Fig. 2c. FIG. 4 is a block diagram showing an example of a circuit that supplies various calculation parameters used in FIG. 1, and FIG. 5 is an embodiment of the present invention in an AM calculation type musical tone synthesis method. FIG. 6 is a block diagram showing an operator used to generate a modulated wave function or modulating wave function by combining the waveform changing function of the modulated wave function or modulating wave function according to the present invention with another waveform changing function. A block diagram showing an embodiment of the unit,
FIG. 7 is a diagram showing an example of the shape of a function waveform obtained from the operator unit of FIG. 6. 10, 60...Modulation wave function generator, 20, 50
...Modulated wave function generator, 11, 21, 51, 6
1... Sine wave table, 22, 52... Code control circuit, 23, 53... Code conversion circuit.

Claims (1)

[Claims] 1. In a musical tone synthesis method for synthesizing a musical tone signal based on a predetermined modulated signal calculation using a modulating signal and a modulated signal, phase data is used to generate at least one of the modulating signal and the modulated signal. generating a predetermined waveform based on the phase data from a storage means storing the predetermined waveform; identifying a predetermined phase section of the phase data based on the phase data; A musical tone synthesis method comprising: inverting the polarity of a portion corresponding to this phase interval; and using a waveform with this predetermined interval inverted for the modulation calculation. 2. The musical tone synthesis method according to claim 1, wherein the modulation calculation follows a predetermined frequency modulation calculation formula. 3. The musical tone synthesis method according to claim 1, wherein the modulation calculation follows a predetermined amplitude modulation calculation formula.