JPS60111298A - Electronic musical instrument - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field of the invention The present invention relates to an electronic musical instrument in which a musical sound waveform is formed by individually calculating the waveform amplitude value of each sample point of a musical sound waveform by Fourier synthesis. This invention relates to an electronic musical instrument that can effectively change the musical sound waveform temporally with a small amount of waveform synthesis calculation by performing interpolation calculations on the musical sound waveform calculated and synthesized at temporally representative points at smaller time intervals. .

(2) Prior art and problems Conventionally, in digital electronic musical instruments, the waveform amplitude value of each sample point of a musical sound waveform is generated by some method.
Many methods have been proposed in which this is read out at a readout rate that corresponds to the pitch frequency. The simplest method is the so-called "waveform memory method" in which the waveform data itself is stored and read out, and a method in which analog input is A/D converted into waveform data is also similar to this method. However, in order to change the musical sound waveform according to the musical range, an enormous memory capacity is required, and the musical sound waveform does not change over time. Other methods have been considered, such as recording parameters using various continuous functions or calculating temporal changes in musical waveforms in real-time waveform synthesis using a frequency modulation method. The correspondence with the timbre of musical tones is extremely unnatural to human senses, and it has been difficult to obtain the desired timbre.

On the other hand, since the harmonic coefficient parameters of the musical waveform generation method using Fourier synthesis naturally correspond to auditory timbre evaluation, it has been widely adopted along with various improvements to compensate for the drawback that it requires a large amount of waveform synthesis calculations. It's here. In the musical sound waveform generation method using Fourier synthesis, it is the composition ratio of harmonic coefficients that determines the timbre of a musical sound, and in order to make the musical sound waveform change over time, multiple memories are used to select many harmonic coefficients. A method was considered to do this, but it had the drawback that the circuit scale was enormous and sufficient timbre change could not be obtained. Method of multiplying "formant filter" and JP-A-5-7-172396
In the method described in the above issue, in which a time-varying function is multiplied by each harmonic coefficient, a multiplication circuit for the harmonic coefficient is required, and a multiplication-accumulation operation is also performed in the musical waveform calculation. However, calculating individual temporal changes over high-order harmonic coefficients has limitations in terms of circuit scale, amount of calculation, calculation speed, etc., and has the disadvantage that it is not sufficient for calculating temporal changes in musical sound waveforms using digital methods. there were.

(3) Structure and Purpose of the Invention The present invention has been developed in view of the above points, and it is an object of the present invention to increase the circuit scale and calculation speed of a musical sound waveform generation circuit that calculates and synthesizes musical sound waveforms that change over time. The present invention is characterized by comprising an interpolation circuit for calculating waveform interpolation values corresponding to minute time intervals, and a storage circuit for storing target values and current values for the waveform interpolation.

(4) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a conceptual diagram for explaining the configuration of an electronic musical instrument according to the present invention, in which 3 is a key press detection/sound generation assignment circuit;
5 is a harmonic coefficient circuit, 5 is a waveform generation circuit, 6 is a waveform storage circuit, 7 is a pitch frequency circuit, 8 is a D/A conversion circuit, and 9 is an envelope circuit.

That is, in the press m detection/sound generation assignment circuit 3, control signals corresponding to the timbre information and performance information inputted from the keyboard 1 and the timbre setting tablet 2 are supplied to each part.

In the harmonic body number VB4, Fourier harmonic coefficients for musical sound waveform synthesis calculation are set in accordance with the timbre information from the five key press detection/tone generation assignment circuit 3. In the waveform generation circuit 5, musical sound waveforms are sequentially calculated and synthesized using the Fourier harmonic coefficients from the harmonic coefficient circuit 4, and are supplied to the waveform storage circuit 6. On the other hand, in the tone pitch frequency circuit 7, key press detection and
A readout signal corresponding to the musical tone frequency is generated based on the performance information from the sound generation allocation circuit 3, and a musical waveform corresponding to the musical tone frequency is read from the waveform storage circuit 6. In the envelope cycle v89, amplitude modulation data such as the rise and fall of individual musical tones and envelope characteristics are set based on the performance information from the key press detection and sound generation assignment circuit 3. (The above operations can be performed digitally in time division to save circuit size.) D/A conversion circuit 8
, the musical waveform corresponding to the musical tone frequency read out from the waveform storage circuit 6 by the pitch frequency circuit 7 is digital-to-analog converted, multiplied by the amplitude modulation data from the envelope circuit v89, and the analog No. 48 output is obtained. obtain.

The analog signal output from the D/A conversion circuit 8 is an effect circuit,
The sound system 10, which includes an amplifier and a speaker, converts the sound into sound, and can produce it as the sound of an electronic musical instrument.

FIG. 2 shows a specific configuration example for explaining the musical sound waveform synthesis calculation processing section provided in the waveform generation port F85 shown in FIG. 1 and related to the main generation. In FIG. 2, 11 is an arithmetic circuit that performs a Fourier synthesis operation, 12 is an in-function generation circuit that generates trigonometric function data for the Fourier synthesis operation, and 13 is an interpolation circuit that interpolates musical waveform data that is the operation result of the arithmetic circuit 11. 14 is a current value memory circuit in which the musical waveform data that can be read out represents the current value; 15 is a target value memory circuit that temporarily stores the target value for calculation; 15 is a target value memory circuit r81
3 and a waveform interpolation circuit that obtains musical waveform data interpolated by the musical waveform data of the current value memory circuit v814; 16 a timing circuit that controls time division timing within the waveform generation circuit 5 and operation timing with the entire circuit; 17 is a write circuit that writes the output musical waveform data of the waveform interpolation circuit v815 into the current value memory circuit 14; 18 is a read circuit that reads the musical waveform data from the current value memory circuit 14 and finally supplies it to the waveform storage circuit 6. .

Regarding the specific configuration example shown in FIG. 2, the operation up to calculation and synthesis of musical sound waveforms in the waveform generation circuit 5 will be explained as follows.
Generally, in the waveform generation circuit 5, the amplitude values of musical tone waveforms can be sequentially calculated using the following formula: F(s)=ΣCn-5in(2πns/5)n=1 (1). here n
is the harmonic order, N is the highest harmonic order, S is the sampling point, S is the number of samples in one period, Cn is the harmonic coefficient circuit 4
is the harmonic coefficient set by . Although equation (1) is sufficient when synthesizing a tone with a constant musical sound waveform, when synthesizing a musical sound waveform that changes over time, it is necessary to set a temporal parameter in addition to this sampling constant S. Using, F(s, t) = Σ Cn(t)・5in(2πns/
S) n:1 ------- It is necessary to perform the calculation according to equation (2). This calculation is essentially asynchronous calculation parameters: s and t require one change each time s and t change, so the number of harmonics is limited to a small number due to circuit scale and operating speed limits, and the accuracy of sampling points for one cycle is limited. It's something I have to do.

In the specific configuration example shown in FIG. 2 for explaining the musical sound waveform synthesis calculation processing part according to the present invention, the musical sound waveform synthesis calculation as described above is executed only at a plurality of temporal representative points, and the interpolation By using the circuit 15 to obtain interpolated values of a plurality of waveforms corresponding to points on the time axis that are smaller than the plurality of temporal representative points, the time of the musical waveform can be effectively calculated with a small amount of waveform synthesis calculations as a whole. Achieve positive change. To explain this operation using the waveform diagram shown in Fig. 4, Fig. 4(a) shows a value obtained by linearly interpolating the number value P1 at time T1 and the sample value P2 at time T2 using the conventional waveform interpolation method. Q1, and then the value R1, value R2, . . . Although this waveform supplementation method is effective for compensating for the roughness of sample points in waveform data, very high-speed interpolation calculations are required to follow the temporal changes in musical waveforms in real time. , low-order interpolation is often used as a sampling noise removal method.
Figure (b) shows the operation of the interpolation circuit 15 according to the present invention, in which the current tone waveform L1 and the tone waveform L2 at a certain point in time representative of temporal changes correspond to the same sample time T3. From sample values Sl and S2, a value R1, a value R2, or a value R31, . . . is determined as an interpolated value of these thimble values S1 and S2. The difference between the waveform interpolation methods shown in Fig. 4(a) and Fig. 4(b) is that the former interpolates between two points of one type of waveform at a high speed corresponding to the sampling speed, so to speak, as an interval of 7Il1 on the time axis. On the other hand, the latter method according to the present invention is, so to speak, interpolation of sample values of two types of waveforms, and the musical waveform L2 at a certain point in time representing a temporal change can be set at a slow speed of several hundred times the sampling interval. This is very effective for realizing time-varying changes in musical sound waveforms with high precision.

In FIG. 2, with the calculation amount f811, Fourier waveform synthesis calculation at time t is performed according to equation (2). For example, when a harmonic coefficient as shown in FIG. 5(a) is given from the harmonic coefficient circuit 4, a waveform signal Fl(x ) is obtained and transferred to the target value memory circuit 13. Next, after a certain period of time corresponding to the temporal change of the musical sound waveform, the harmonic coefficients as shown in FIG. A waveform signal F2(x) as shown in FIG. 6(b) is obtained from the circuit 11 and can be transferred to the target value memory circuit 13 again. The interpolation circuit 15 performs an interpolation calculation to obtain an interpolated value between the musical tone waveform data in the current value memory circuit 14 and the musical tone waveform data in the target value memory circuit 14, and the calculation result is transferred to the current value memory circuit 14 again. Store as musical waveform data. To explain this operation using the waveform diagram shown in FIG. 7, in general, in order to make the intervals between waveform A and waveform E in FIG. 7(a) equal, such as waveform 81 waveform 01 waveform, 2 corresponding to the musical waveform data of the waveform of FIG. 7(a) and the musical waveform data of waveform E.
In addition, a third memory circuit is also required to store tone waveform data roughly corresponding to the waveform 81 waveform 01 waveform resulting from the interpolation calculation. However, in the interpolation circuit 15 shown in FIG. 2, the waveform shown in FIG. In the case of waveform data, the first interpolation calculation result will be like waveform B in Figure 7(b), and this can be stored again as a musical sound waveform of 814 in the current value memory, so the interpolation operation can be performed in two types of memory This is done by a circuit.In the second interpolation operation,
The waveform B in FIG. 7(b) is the musical sound waveform data in the current value memory circuit 14, and the waveform G in FIG. 7(b) is the musical sound waveform data in the target value memory circuit 13, and the interpolation calculation result is The waveform becomes like the waveform C in FIG. 7(b), and this is stored again as a musical tone waveform in the current value memory circuit 14. Expressing the above interpolation calculation according to equation (2), the musical waveform data of the target value memory circuit 13 that is calculated and synthesized at regular intervals is as follows: Fl(s, tl,) = Σ Cn(tl)・5in(2
7Cns/5) n=1- ------ Expression (3) is obtained, and on the other hand, the musical waveform data of the current value memory circuit 14 is F2(s, t)-ΣCn(t)・5in(27Cns/
S) n: 1 ---- It can be expressed as equation (4). For example, if we set a constant asymptotic parameter 2M and obtain the interpolation result: IP(s, t), then IP(s, t)=F2(s, t) +M・(Fl(s ,tl)-F2(s,t))--1-
- Equation (5) is obtained. This is F2(s, t'
), so the overall recurrence formula representing the waveform interpolation calculation is (Fl (s, tl) - F2 (+1 for s, t)) = (using the number of interpolation calculations: k)
M・(F Hs, tl) −F2(s, t, k))−−
---The general solution is I P (s, t, k) = Fl( s, tl)・(1-
M'-')+I P (s, t, 1)・M'-' ------ Formula (8) is obtained, and asymptotic interpolation is performed exponentially as shown in Figure 7(b). . Conditions that affect this operation include the asymptotic parameter: M, for example, M = 0.5 (or 2
(the n-th root of ), the interpolation circuit 15 in FIG. are obtained as waveforms D1, E1, and F in FIG. 7(b), and it can be seen that the waveforms change more smoothly. Also, if we pay attention to the calculation speed, it is sufficient that the musical waveform data changes in the operation of calculation cycle V811 at a relatively long time interval every time the Fourier waveform synthesis calculation is completed according to equation (2). A sufficient performance H of 2 to 3 m5ec from the perspective of human perceptual discrimination ability.
You can estimate the time. On the other hand, in equation (2), by changing the harmonic coefficient Cn (t) in real time, the harmonic coefficient circuit 4
When supplying data from have.

FIG. 3 shows the waveform generating circuit 5 provided in the waveform generation circuit 5 shown in FIG.
This is another specific configuration example for explaining the musical sound waveform synthesis calculation processing section according to the present invention. In FIG. 3, 5 is a waveform generation/waveform interpolation circuit as shown in FIG. 2, 21 is an interpolation value memory circuit that temporarily stores the output musical waveform data from the waveform generation/waveform interpolation circuit 5, and 22 is an interpolation value memory I
A temporal interpolation circuit 23 temporally interpolates the musical waveform data of the gIN 21, and a time setting circuit 23 that controls the operation timing of the waveform generation/waveform interpolation circuit 5 and the temporal interpolation circuit 22. That is, after performing the above-mentioned waveform interpolation operation I as shown in FIG. 4(b), a conventional temporal interpolation operation as shown in FIG. 4(a) is performed. To explain this operation following equation (8), the musical waveform data transferred to the interpolated value memory circuit 21 is an interpolated value that is transferred from the waveform interpolation circuit 15 to the current value memory circuit 14 from time to time. Using j for s, t, I P (
s, j, t, k) ---- Expressed as in equation (9). Here, S is the sample point of the waveform synthesis calculation, j is the temporal interpolation parameter in the temporal interpolation circuit 22, t is a plurality of temporal representative points for musical waveform synthesis, and k is the waveform in the waveform generation/waveform interpolation circuit 5. It is an interpolation parameter. The temporal interpolation circuit 22 performs an interpolation operation on the sample point S, and calculates the following equation: IP(s, j, t, k) = IP(s, 1.t, k) + Q(j)(IP(s+1.1. t,k)-IP(s
, 1. t, k)) --- Obtain the temporal interpolation value of equation (10). Here, QU) is the success or failure of interpolation that determines the interpolation characteristics, and in the case of linear interpolation as shown in Figure 4(a), it is realized by a linear function, and in the case of exponential interpolation, it is realized by a shift circuit as described above. Real l by etc.
! I can do it. In the specific configuration example shown in FIG.
8 configuration is relatively large-scale, but when considered as the overall operation of musical sound waveform synthesis calculations, it is superior to conventional electronic It is a method that enables the execution of a computational amount that was impossible to achieve with conventional methods, and it functions effectively depending on the parameter settings.

(5) As described in detail, according to the present invention, in an electronic musical instrument in which a musical sound waveform is formed by Fourier synthesis W,
There is no need for a high-speed circuit configuration that calculates temporal changes in musical sound waveforms, and the musical sound waveforms that are calculated and synthesized at low speed are interpolated and calculated at minute time intervals using a feedback storage circuit and an interpolation circuit, resulting in less waveform synthesis. By realizing a musical sound waveform generation method that effectively temporally changes the musical sound waveform using the amount of calculation, it is possible to easily provide electronic music with rich musicality, contributing to high-quality music. It's a big deal.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram for explaining the configuration of the electronic Tokai according to the present invention, and FIG. 2 is a waveform generation circuit 5 shown in FIG. 1.
A specific configuration example for explaining the musical sound waveform synthesis calculation processing section according to the present invention, which is provided in the waveform generation circuit 5 shown in FIG. 1, is shown in FIG. A specific configuration example, FIG. 4, for explaining another embodiment of the musical sound waveform synthesis recitation processing section is a waveform diagram, FIG. 5, and a waveform diagram for explaining the operation of the specific configuration example shown in FIG. 6 is a waveform diagram for further explaining the operation of the specific configuration example shown in FIG. 2, and FIG. 7 is a waveform diagram for simplifying the explanation of the operation of the specific configuration example shown in FIG. 2. It is. In the same figure, 1 is an M board, 2 is a tone setting tablet, and 3 is a tone setting tablet.
4 is a harmonic coefficient circuit, 5 is a waveform generation circuit, 6 is a waveform storage circuit, 7 is a pitch frequency circuit, 8 is a D/A conversion circuit, 9 is an envelope circuit, and 10 is a key press detection/sound generation assignment circuit. Sound system, 11 is an arithmetic circuit, 12 is a sine function generation circuit, 13 is a first memory circuit, 14 is a second memory circuit, 15 is an interpolation circuit, 16 is a timing circuit, 21
2 is an interpolation value memory circuit, 22 is a temporal interpolation circuit, and 23 is a time setting circuit. Patent applicant TI T2 (hour 6) T3 (hour) Figure 4

Claims (6)

[Claims] (1) In an electronic musical instrument that forms a musical sound waveform by individually calculating the waveform amplitude value of each sample point of the musical sound waveform by Fourier synthesis, it is possible to perform a musical sound waveform that changes over time at multiple temporal representative points. W. A musical sound waveform generation circuit for synthesizing, a target value storage circuit that temporarily stores the musical sound waveform calculated and synthesized in the musical sound waveform generation circuit as a target value, and a current value storage circuit in which the musical sound waveform read out represents the current value. , reads out the 2 m musical sound waveform from the target value storage circuit and the current value storage circuit, and calculates an interpolated value of the musical sound waveform corresponding to a point on the time axis that is smaller than the plurality of quantitative representative points. The waveform interpolation circuit and the waveform 7 interpolation r&
The output waveform of one circuit is the current value. The present invention is provided with a write circuit for rewriting to the memory circuit and a read circuit for reading out the musical sound waveform output from the current value memory circuit, so that the musical sound waveform can be effectively temporally changed with a small amount of waveform synthesis calculations. Characteristic electronic musical instruments. (2) In an electronic musical instrument in which a musical sound waveform is formed by individually calculating the waveform amplitude values of each simple point of a musical sound waveform by Fourier synthesis, a musical sound waveform that changes over time is divided into multiple temporally representative points. a musical sound waveform generating circuit that calculates and synthesizes the musical sound waveform in the musical sound waveform generating circuit; a target value storage circuit that temporarily stores the musical sound waveform calculated and synthesized in the musical sound waveform generating circuit as a target value; and a current value storage circuit that causes the musical sound waveform read out to represent the current value. and reading out the two types of musical sound waveforms from the target value storage circuit and the current value storage circuit, and calculating an interpolated value of the musical sound waveform corresponding to a point on the time axis that is smaller than the plurality of temporal representative points. a write circuit for writing the output waveform of the waveform interpolation circuit into the current value storage circuit; an interpolation value storage circuit for temporarily storing the output signal of the waveform interpolation circuit; Equipped with a temporal interpolation circuit that reads the musical waveform amplitude value data of two consecutive sample points and calculates the interpolated values of multiple waveforms corresponding to the finer sample points in gJ, it is possible to effectively generate musical sounds with a small amount of waveform synthesis calculations. An electronic musical instrument characterized by a waveform that changes over time. (3) In the waveform interpolation circuit, the 21 values read out from the target value storage circuit and the current value storage circuit
1! 3. The electronic musical instrument according to claim 1, wherein the musical sound waveform amplitude data is interpolated and approximated at a constant ratio. (4) In the waveform intervening circuit, the 2s read out from the target value storage circuit and the current value storage circuit
Claim 1, characterized in that a plurality of interpolated values of the musical sound waveform corresponding to points on the time axis that are smaller than the plurality of temporal representative points are calculated using the musical sound waveform. or the electronic musical instrument described in paragraph 2. (5) In the waveform interpolation circuit, a weight setting circuit that sets a weighting function for the two tone waveforms, and a time varying circuit that temporally changes the weighting function;
claim 4, further comprising an interpolation calculation circuit that calculates an interpolation value from the musical waveform data of No. 1 and the weighting function, so that the temporal change state of the waveform interpolation calculation can be arbitrarily controlled. Electronic musical instruments listed in section. (6) The waveform interpolation circuit includes a difference value setting circuit that sets a difference value between the two types of musical waveform amplitude data, and an incremental value setting circuit that binary-shifts the difference value and sets incremental value data. , comprising an interpolation calculation circuit that calculates an interpolation value from the 2m musical waveform data and the incremental value data, and is capable of exponentially controlling the temporal change state of the waveform interpolation calculation. An electronic musical instrument according to claim 4.