JP2661601B2 - Waveform synthesizer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform synthesizer for forming a musical tone waveform used in an electronic musical instrument that outputs various musical instrument sounds or human voice sounds. [0002] In recent years, as a musical sound synthesizer for electronic musical instruments,
As digital technology has been used, the improvement in tone quality has been remarkable. Such a technique is disclosed, for example, in Japanese Patent Publication No. 58-57979. Hereinafter, the above-described waveform synthesizing apparatus will be described with reference to the drawings. FIG. 6 shows a configuration of a conventional waveform synthesizer. In FIG. 6, reference numeral 101 denotes a keyboard input unit for instructing output musical tones, 102 a count control unit for counting clocks, 103 a waveform memory for storing waveform data, 104 a selector for selecting an input, and 106 processing waveform data. A filter 105 is a shift register for delaying an input, and 107 to 111 are data (signal) transmission lines. The operation of the waveform synthesizing apparatus configured as described above will be described below. When a keyboard input for designating a musical tone to be output is made, the keyboard input unit 101 supplies a clock corresponding to the pitch of the output musical tone to the transmission path 107. Waveform memory 10
Numeral 3 indicates that N waveform data corresponding to one cycle of the musical tone waveform are transmitted according to the clock timing of the transmission path 107.
08. The count control unit 102 includes a transmission path 107
And the switching drive output is output to the selector 104 after the count value reaches the above N. The selector 104 controls the transmission path 108 until the switching drive output is input.
Is selected, and after the switching drive output is input,
The transmission path 109 is selected. The waveform data that has passed through the selector 104 is output as a musical tone waveform and input to a filter 106. The filter 106 digitally filters the input waveform data and outputs it to the shift register 105. The shift register 105 functions as a delay unit having a number of stages equal to the N, and executes a shift operation according to the timing of the clock on the transmission line 107. With the above operation, after the N one-cycle waveform data output from the waveform memory 103 is output through the selector 104, the filter 106, the shift register 105, the selector 104, and the transmission lines 109 to 111 are output.
, A one-cycle waveform is output while circulating in a closed loop composed of However, in the above-described configuration, when synthesizing a so-called attenuated tone such as a piano or guitar, a waveform circulating in a closed loop many times is gradually filtered. Although it is suitable for obtaining a changing situation, in order to synthesize a so-called stationary tone such as a flute trumpet, the filter 106 is set to a so-called through state, that is, the filter 106
Had to be eliminated. In addition, the musical tone obtained in such a manner simply outputs a one-cycle waveform repeatedly, and thus has a problem that the tone becomes mechanical and monotonous. SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a waveform synthesizing apparatus capable of obtaining a natural sound as a stationary tone, in particular, by modeling a sounding mechanism of a musical instrument. In order to achieve this object, a waveform synthesizing apparatus according to the present invention is provided with a waveform memory for storing a driving waveform for driving a resonance section or a loop section of a musical instrument. A waveform control unit that selects a drive waveform stored in the waveform memory in accordance with the type, pitch, and touch of a musical tone to be output during the production of the musical tone in accordance with the pronunciation instruction of the musical tone;
Among the drive waveforms selected according to the instruction from the waveform control unit, the drive waveform is longer than the time delay of the loop unit.
A drive waveform reading section for reading output time of the drive waveform from the waveform memory, is composed of a said loop portion
The loop section includes an adder having the drive waveform as one input, and a time delay corresponding to a pitch of a musical tone to be output to the adder output and a resonance characteristic of a musical instrument for forming a pitch sound. It consists tone waveform imparted with bets from the digital filter so as to obtain the other input of the adder, the de
The digital filter is a filter characteristic corresponding to the resonance characteristics of the instrument.
It has a property. According to this configuration, the waveform control unit selects a drive waveform based on a musical tone type, a pitch, and a touch.
The drive waveform readout unit reads the selected drive waveform from the waveform memory according to the readout data instructed by the waveform control unit, and outputs the readout drive waveform to the adder. The adder adds the output of the digital filter, which is a zero value in the initial state, to the drive waveform, and outputs the result. The digital filter filters the adder output using filter coefficients based on the musical tone type and pitch, and then outputs the result as an adder input. With the above operation, the driving waveform corresponds to, for example, the vibration of the mouthpiece portion of the clarinet, ie, the reed, and the operation of the loop portion constituted by the digital filter and the adder causes the vibration of the clarinet body, ie, the vibration in the resonance tube. Since a driving waveform corresponding to a touch can be supplied, a natural musical sound can be obtained. In the above, the output waveform of the musical tone is obtained from an output terminal attached to an arbitrary predetermined point such as an output terminal of an adder or an output terminal of a digital filter. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a waveform synthesizing apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an input unit such as a keyboard, 2 denotes a drive waveform generator which outputs a drive waveform corresponding to information on a musical tone type, pitch and touch transmitted from the input unit 1, and 6 to 11 denote data transmission. The path 3 is an adder, and 4 is a digital filter. Using A or B as an output terminal, an output tone waveform is obtained from this.
Reference numeral 5 denotes a loop unit, which includes an adder 3, a digital filter 4, and a transmission path 910. Reference numeral 12 denotes a reference clock generator for supplying operation timing to the outside. The operation of the embodiment configured as described above will be described below. First, when a musical tone to be output is specified to the input unit, the input unit 1 outputs data relating to a musical tone type and a pitch touch to the transmission path 6 in accordance with the input, and outputs data relating to the musical tone type and the pitch. Is output to the transmission path 7. Data relating to the start or end of the output of a musical tone called key-on or key-off is naturally output from the input unit 1 to the transmission lines 6 and 7. The input unit 1 outputs to the transmission path 6 data relating to a touch that changes in response to a musical sound instruction input. The drive waveform generator 2 generates a drive waveform corresponding to the tone type, pitch and touch data input from the transmission line 6. The drive waveform generator 2 can be realized by, for example, a configuration as shown in FIG. In FIG. 2, a waveform memory 20 storing a plurality of drive waveform data corresponding to a tone type selects specific drive waveform data according to a memory selection signal output from a waveform control unit 21 corresponding to a tone type. Is done. On the other hand, the waveform control unit 21 outputs numerical data corresponding to a pitch, generally called a frequency number, for establishing a pitch at the time of a fixed clock. With respect to the output frequency number, address data for reading out the selected specific drive waveform data in the waveform memory 20 is transmitted to the transmission line 32 by the accumulating means including the adder 25 and the transmission line 32. The waveform memory 20 outputs one point of drive waveform data determined by the transmission lines 29 and 32 to the transmission line 34. The waveform control section 21 outputs the touch data to the transmission path 27. Reference numerals 22 and 23 denote converters for converting (scaling) the touch data of the transmission line 27 into appropriate numerical values. The converter 22 output of the touch data corresponding to the pitch changes the frequency number of the transmission line 28. The multiplication is performed in the multiplier 24. On the other hand, the output of the converter 23 of the touch data corresponding to the volume is multiplied by the multiplier 26 so as to change the drive waveform data of the transmission path 34. The drive waveform data output to the transmission line 8 as described above is referred to as a final drive waveform. In the above, the operation of each unit is based on the clock output from the reference clock generator 12 to the transmission line 11. By appropriately restricting the number of bits of the transmission line 32, that is, by using it as a so-called ring counter, the driving waveform transmitted to the transmission line 8 can be used as the driving waveform data selected in the waveform memory 20. Is compressed in the time direction or amplitude direction according to the touch data.
It becomes a waveform obtained by repeating while being expanded. FIG. 2 shows a driving waveform generator 2 constituting the present invention.
In addition to the above, it is added that it is also possible to use a known technique to generate a drive waveform data by calculation without using the waveform memory 20, for example. The driving waveform output to the transmission line 8 is output to the digital filter 4 after passing through the adder 3 in FIG. Here, it is assumed that the other input to the adder 3, that is, the output of the digital filter 4, is initially set to a zero value. The drive waveform filtered by the digital filter 4 is output to the transmission path 10 and then added to the drive waveform by the adder 3. It is assumed that the digital filter 4 and the adder 3 operate according to the clock of the transmission line 11. During the operation described above, the output tone waveform is shown in FIG.
Alternatively, it is obtained from the output terminal of B. In the configuration according to the present embodiment, when the driving waveform is, for example, the vibration waveform of the clarinet reed, the loop portion 5 corresponds to the body of the clarinet, that is, the resonance tube. The outputs of the tubes will be combined. If A in FIG. 1 is an output terminal, the tone waveform of the sound obtained by attaching a pickup microphone directly below the mouthpiece of the clarinet, and if B in FIG. A tone waveform of a sound with a pickup microphone attached to an arbitrary point can be obtained. FIG. 3 shows an embodiment relating to the digital filter 4. The digital filter control unit 30 shifts the shift register 31 according to the pitch of the musical tone input from the transmission path 7.
, That is, the number m of stages, and outputs coefficients C1 and C2 for multiplication by the multipliers 33 and 34. In order to obtain a tone having a pitch corresponding to, for example, 10 clocks in the number of clocks on the transmission path 11, for example, C1 = 1, C2 = 0,
m = 10. To obtain a musical tone having a pitch corresponding to 10.5 clocks, for example, C1 = 0.5, C2 =
0.5, m = 10. That is, when the number of clocks corresponding to the pitch of the musical tone to be output, that is, the number of waveform data is P, m is determined as the largest positive numerical value not exceeding P, and C1 and C2 are determined by the following equations. I do. X = P−m C1 ≦ (1−X) · K (1) C2 ≦ X · K In the above example, the value of K in the equation (1) was set to 1,
In this state, depending on the drive waveform, the loop 5
In this case, since the waveform data value rapidly increases and enters an oscillation state, it is desirable that the value of K be 0.1 or less. FIG. 3 shows an embodiment. In addition, a known digital filter technique can be used. FIG. 5 shows an example in which a transversal filter is used as the digital filter 4. In FIG. 5, the digital filter control unit 3
0 generates a coefficient sequence corresponding to the type of musical tone input from the transmission path 7. This sequence of coefficients corresponds to the impulse response of the actual instrument, for example the clarinet body or the resonance tube. Therefore, in this case, the drive waveform can be obtained by performing a deconvolution operation of the impulse response of the resonance tube with respect to the musical tone waveform actually output from the clarinet using a known digital filter technique. This coefficient sequence is redistributed according to the pitch. That is, for example, when outputting a sound having a pitch one octave lower than the pitch at the time of the impulse response measurement in which the number of coefficient sequences is ten, the coefficient sequence becomes twenty, for example, by performing linear interpolation, 20 from the coefficient sequence consisting of 10 coefficients
Obtaining the number of coefficients is called reallocation. The coefficient sequence obtained in this way is output with respect to the output from the unit time delay element indicated by Z-1 and these are multiplied respectively. In this way, it is possible to use a drive waveform having a length irrespective of the delay time defining the pitch even for a stationary tone such as a clarinet or an attenuated tone such as a piano. Therefore, it is possible to generate a non-integer harmonic component with respect to the pitch of the output musical tone. As described above, according to the present embodiment, the drive waveform output from the drive waveform generator 2 changes in pitch and volume in accordance with the touch-related data, so that the drive waveform of the actual musical instrument is changed. Since the digital filter 4 in the loop unit 5 has a feedback loop corresponding to a constant pitch corresponding to the body (resonance system) of an actual musical instrument, the digital filter 4 causes the feedback loop to interfere with the adder 3. Therefore, since a synthesis system that is close to the sounding state of an actual musical instrument is configured, a natural sound can be obtained. Furthermore, by using a transversal filter as a digital filter,
As a result, it is possible to simultaneously control the number of delay stages only by adjusting the coefficient. Hereinafter, another embodiment of the present invention will be described with reference to the drawings. In FIG. 4, 40 and 41 are first and second digital filters, respectively, and B is an output terminal. Except for the loop section 5, the configuration is as shown in FIG. 1 similarly to the first embodiment. The operation of the second embodiment configured as described above will be described below. The waveform data output from the adder 3 is the first waveform data.
After being filtered by the digital filter of (2), the signal is output from the output terminal B as an output tone waveform and the second
Is filtered by the digital filter 41. Here, the first and second digital filters have the same or opposite phase characteristics, and the delay time included in the first and second digital filters is determined by the pitch of the musical tone to be output. Is equal to or equal to half of the clock number P corresponding to. As described above, according to the present embodiment, the digital filter processing is divided into the first digital filter and the second digital filter, and the output of the first digital filter is set to the output musical tone waveform. Between the first and second digital filters corresponding to the traveling wave and the reflected wave, a natural sound closer to a musical instrument sound can be obtained. According to the present invention, the reading speed, which changes according to the touch of the driving waveform output from the driving waveform reading unit, and the time delay of the digital filter corresponding to the pitch are controlled separately, Since the drive waveform and the waveform filtered by passing through the digital filter are added, the same state as the interference between the drive unit and the torso, that is, the resonator, can be realized as in the case of the actual musical instrument. A natural instrument sound corresponding to the change of the drive waveform according to the above can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a waveform synthesizing apparatus according to a first embodiment of the present invention. FIG. 2 is an exemplary block diagram of a driving waveform generating unit according to the present invention. FIG. 4 is a block diagram of a waveform synthesizer according to a second embodiment of the present invention; FIG. 5 is an exemplary block diagram of a digital filter according to the present invention; FIG. [Description of Signs] 1 Input unit 2 Drive waveform generation unit 3 Adder 4 Digital filter 5 Loop unit 12 Reference clock generation unit 20 Waveform memory 21 Waveform control unit 25 Adder 26 Multiplier

Claims (1)

(57) [Claims] A waveform memory for storing a drive waveform for driving a resonance portion or a loop portion of the musical instrument; and, according to a designated tone generation instruction, a tone corresponding to the type, pitch and touch of a tone to be output during tone generation. A waveform control unit for selecting a drive waveform stored in the waveform memory; and the loop among the drive waveforms selected according to an instruction from the waveform control unit.
A drive waveform readout unit that reads out and outputs a drive waveform for a time longer than the time delay of the unit from the waveform memory;
The loop section, wherein the loop section generates an adder having the drive waveform as one input, and a time delay and a pitch sound corresponding to a pitch of a musical tone to be output to the adder output. is the resonance characteristics and tone waveform imparted with instruments for forming is composed of a digital filter so as to obtain the other input of the adder, the digital filter of the instrument
A wave synthesizer having a filter characteristic corresponding to a resonance characteristic .