JPS59168493A - Musical tone waveform generator - 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 Technical Field The present invention relates to an apparatus for storing a plurality of periodic waveforms and generating a musical sound waveform using a single waveform memory, and is used in electronic musical instruments and the like.

2. Description of the Related Art A method of generating a single musical tone by storing a continuous plurality of cycles of musical sound waveforms on a semiconductor memo and reading them out at a specific rate has heretofore been known.

In this type of musical sound generation method, the memory capacity tends to be enormous because it originally stores multi-period waveforms, but if you try to store waveforms that include many harmonic components of higher orders, the memory capacity becomes even larger. A huge amount of memory is required. One of the reasons for this is that a large number of harmonic components are synthesized and a single waveform is created by adding each harmonic level (thus,
The amplitude value tends to be large, so the waveform amplitude value 1
This is because the number of bits per word tends to increase. In this case, reducing the number of bits per word lowers the resolution, making it impossible to express complexly changing waveforms. Another reason is that in order to include all the harmonics as high as possible, the sampling frequency must be very high to satisfy the sampling theorem for the highest harmonics, which requires an increase in the number of memory addresses. That's because you don't get it. In this way, when trying to store high-quality waveforms containing many high-order harmonic components, there is a problem in that the memory size becomes large, both in terms of the number of waveform memory addresses and the number of words for air address reverberation. child.

OBJECT OF THE INVENTION The present invention aims to solve the above-mentioned problems.It is an object of the present invention to reduce the size of a waveform memory that stores multi-period waveforms, and to produce high-quality musical tones containing a large number of high-order harmonic components. It is intended to generate a waveform.

Summary of the Invention According to the present invention, a waveform memory that stores waveforms spanning multiple periods and a waveform calculation circuit that synthesizes waveforms by calculation using parameters are provided, and the output of the waveform memory and the output of the waveform calculation circuit are provided. A desired musical sound waveform can be obtained by combining. The waveform memory stores not the desired tone waveform itself, but a waveform with some component missing. Therefore, when a desired continuous waveform is completely memorized (in comparison, ■ the number of pits per word can be reduced,
It is also possible to reduce the number of addresses. The waveform calculation circuit reads out the waveform from the waveform memory and calculates a waveform corresponding to the difference between the waveform to be processed and the desired musical sound waveform. As a result, a desired tone waveform can be obtained by adding and synthesizing the read waveform and the calculated waveform. In the waveform calculation circuit, parameters used for waveform calculation can be changed according to the progress of waveform generation, thereby realizing temporal waveform changes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, a key switch circuit 10 detects key depressions and key releases of various companies on a keyboard, and provides data indicating the pressed keys to an address generator 11. The address generator 11 generates an address signal (instantaneous phase information) that changes at a rate corresponding to the frequency of the pressed key. The address signal consists of a lower address ADI and an upper address AD2. For example, the lower addresses A and DI have waveforms 11i! It corresponds to the phase within the iJ period, and the upper address AD2 indicates the number of cycles. The waveform memory 12 stores continuous multiple period waveforms, and the address signal ADI generated by the address generator 11
, A, D], the stored waveforms are sequentially read out under the control of the readout circuit 16.

The waveform calculation circuit 14 calculates the waveform amplitude value according to a predetermined waveform synthesis calculation function, and performs this calculation using the data of the lower address AD1 given from the address generator 11 as phase information (one of the calculation parameters). The calculation is executed using the parameter data provided from the parameter supply circuit 15 as other calculation parameters. Any arbitrary function such as frequency modulation calculation, partial tone synthesis calculation, or amplitude modulation calculation can be used as this calculation function. The parameter supply circuit 15 supplies f parameters according to this arithmetic function. For example, in the case of frequency modulation calculation, the modulation index 1 (shi) which can change over time, the amplitude coefficient A (t), the modulation wave ω of the carrier wave ωC with respect to the fundamental wave
The ratio of m, etc. are supplied as parameters, and in the case of partial tone synthesis calculation, the order, amplitude coefficient, etc. of the partial to be generated are supplied as parameters. Although not shown, it is possible to select a predetermined parameter or arithmetic function according to the output of the timbre selection circuit. It is well known that by changing the values of such calculation parameters, the shape of the synthesized waveform can be changed. Therefore, it is preferable to input data indicating the upper address AD2 to the parameter supply circuit 15, and to switch the value of the parameter every one or more cycles of the waveform according to changes in the upper address AD2, and to supply it to the arithmetic circuit 14. . Note that a key-on signal KON indicating whether or not the key press is sustained is supplied to the parameter supply circuit 15+. Please use it.

The single continuous waveform signal read from the waveform memory 12 and the waveform signal generated from the waveform calculation circuit 14 are added by an adder 16 to synthesize a desired musical waveform signal. This musical waveform signal is finally output to the sound system 17. It is read out or calculated (if the obtained waveform signal is a digital signal, the digital / Although an analog converter is provided, illustration thereof is omitted.

Each component constituting a desired musical sound waveform is shared between the waveform memory 12 and the waveform arithmetic circuit 14, and which component is shared can be arbitrarily determined. Generally speaking, low-order components with relatively large amplitude values are shared by the waveform calculation circuit 14, other components are shared by the waveform memory 12, or harmonic components are shared by the waveform calculation circuit 14.
If the specifications are such that the waveform memory 12 shares the other components, the number of bits per word of the waveform memory 12 can be greatly reduced, and moreover, delicate components can be stored in the waveform memory 12. can be expressed accurately. In addition, the waveform calculation circuit 14 performs calculations using all bits of the lower address AD1 and performs waveform synthesis at a high sampling rate, but the waveform memory 12 performs reading using only the upper bits of the lower address AD1, and It is also possible to reduce the total number of addresses by lowering the sampling rate.

The waveform memory 12 may store the entire waveform for several seconds from the start of the sound to the end of the sound). Alternatively, continuous waveforms of the rising edge and sustaining portion of the sound may be stored, and the rising portion may be read out once and the sustaining portion may be read out repeatedly. In that case, the waveform of the decay part is obtained by repeatedly reading out the sustaining part and adding a decay envelope (this point is omitted from the drawings). It is also possible to store the continuous waveforms of the rising part, the connecting part, and the decay part, respectively, so that the rising part and the decay part are read out once, but the sustaining part is read out repeatedly. Alternatively, the waveform memory 12 may store continuous waveforms individually for each pitch or range. In that case, a storage area storing a predetermined continuous waveform is specified according to the key code indicating the pressed key, and the continuous waveform is read from there.

Of course, the present invention can also be applied to single-tone electronic musical instruments (limited to multi-tone electronic musical instruments). It is preferable to read out the waveform memory 12 and perform waveform calculation in the waveform calculation circuit 14 using a plurality of divided channels.

An example of the address generator 11 is shown in FIG. Accumulate toss at regular time intervals. The modulo number of the accumulator 19 corresponds to the number of addresses for one cycle of the waveform, and the carry signal is accumulated in the second accumulator 20. Thus, the first accumulator 19
, a lower address AD1 is obtained from the second storage router 20, and an upper address AD2 is obtained from the second storage router 20.

As a modification of the present invention, the waveform memory 12 stores one period of a sound source waveform such as a triangular wave or a sine wave, and reads this repeatedly, and calculates the difference between this sound source waveform and a desired musical sound waveform by a waveform calculation circuit. 14 is also possible.

The means for combining the outputs of the waveform memory 12 and the waveform calculation circuit 14 is not limited to the adder 16, but may be a multiplier or other calculator.

Effects of the Invention As described above, according to the present invention, when it is desired to generate a high-quality tone waveform by memorizing a plurality of periodic waveforms in advance for one month, the memory contains part of the components of the desired tone waveform. The continuous waveform is memorized, other components are generated by calculation, and the desired tone waveform is obtained by combining the one waveform generated by the calculation and the continuous waveform read from the memory. , the waveform memory capacity can be saved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one example of the present invention J@11/1, and FIG. 2 is a block diagram showing an example of the address generator of FIG. 1. 10... Key switch circuit, 11... Address generator, 12... Waveform memory, 13... Readout circuit,
14... Waveform calculation circuit, 15... Parameter supply circuit, 16... Adder, A11) 1... Lower address (corresponds to the phase within one cycle of waveform), AD2... Upper address (period) corresponding to the number). Patent applicant: Yoshihito Iizuka, agent of Nippon Gakki Mfg. Co., Ltd.

Claims (1)

[Scope of Claims] 1. A waveform memory storing a plurality of periodic waveforms, a waveform arithmetic circuit that performs waveform synthesis arithmetic using parameters, a circuit that supplies parameters to the waveform arithmetic circuit, and a circuit that controls reading of the waveform memory. The phase information related to this readout phase is then converted to the waveform calculation scale (the echo circuit,
A musical waveform generating device comprising a circuit for synthesizing a waveform signal read from the waveform memory and a waveform signal obtained by the waveform calculation circuit to obtain a desired musical waveform signal. 2 The circuit supplying the parameters is configured such that the waveform generation <-Z
The musical sound waveform generator according to claim 1, which is capable of changing parameter values according to IM.