JPH0799477B2 - Music signal generation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of generating a continuous tone signal by repeating a waveform of a limited plurality of cycles, and in particular, unnaturalness that may occur due to repetition. The present invention relates to a musical tone signal generating method for reducing the noise.

[Conventional technology]

JP-A-52-121313 discloses that all waveforms from the start to the end of musical tone generation are stored in a memory in advance and a high quality musical tone signal is generated by reading this waveform. . However, the method of storing all the waveforms as described above has a disadvantage that the memory capacity becomes huge and the cost becomes high, and continuous sound is substantially impossible to generate. In view of this point, it is also shown in the above-mentioned publication that a plurality of periodic waveforms of the entire tone generation period are stored in a waveform memory and a tone signal is obtained by repeatedly reading this waveform. There is. However, there is a problem that the connection between the repetitive portions becomes unnatural if the repetitive read-out multiple period waveform portions are simply made continuous.

In view of this point, in JP-A-59-188697,
A device for smoothly connecting the terminal end and the starting end of the repeating portion is disclosed.

[Problems to be solved by the invention]

By the way, when a continuous tone signal is generated by repeating a limited number of periodic waveforms, it is of course necessary to smooth the connection between repeating portions as described above, and to feel unnatural periodicity due to repetition. It is also important not to let it happen. If the timbre of the multi-period waveform prepared as a repeating part is stationary, repeating this will not make you feel unnatural periodicity, but if the timbre of this repeating part is not stationary, when you repeat this There was a problem that an unnatural periodicity was felt. This is shown by a graph with timbre variation on the vertical axis,
When a repeating portion where the timbre is relatively stable as shown in FIG. 4 (a) is repeated, an unnatural periodicity of timbre change does not appear as in FIG. 4 (b), but FIG. When a repetitive portion whose tone color is not constant is repeated as shown in FIG. 5, unnatural periodicity occurs in the tone color change as shown in FIG.

The conventional device has been devised to smoothly connect the terminal end and the starting end of the repetitive portion as described above, but has not been specially devised to reduce the unnaturalness caused by the repetitive operation. To reduce such unnaturalness, simply select a waveform whose timbre is in a steady state as much as possible for the waveform of the repetitive portion (sampled from the sound waveform of a natural musical instrument). It is difficult, and many musical instruments do not have such a steady state. For example, in the case of a piano, such a steady state of the tone color does not exist especially in the low temperature part, and the tone color fluctuates with a certain directivity with the passage of time. In this way, it is extremely unnatural for a tone color that changes with directivity to return to the previous tone color in time by repetition.

The present invention has been made in view of the above points, and when a continuous tone signal is generated by repeating a limited plurality of periodic waveforms, it is possible to reduce unnatural periodicity that may occur due to repetition. It is intended to provide a musical tone signal generating method capable of performing the above.

[Means for solving problems]

A tone signal generating method according to the present invention comprises preparing a first plurality of periodic waveforms, obtaining a second plurality of periodic waveforms by rearranging the first plurality of periodic waveforms in a reverse direction in time, Obtaining a combined multiple-cycle waveform by combining the first and second multiple-cycle waveforms at sample points, storing the combined multiple-cycle waveform in a memory, and storing the combined multiple-cycle waveform in the memory The continuous tone signal is generated by repeatedly reading the synthesized plural period waveforms.

[Action]

Since the second plural-cycle waveform is obtained by rearranging the first plural-cycle waveform in the reverse direction in time, it has the directivity opposite to the directivity of the tone color variation of the first plural-cycle waveform. Become. Therefore, by synthesizing both waveforms, the tone color fluctuations are averaged and the directivity is eliminated. As a result, the unnatural periodicity of the tone color change is reduced in the continuous tone signal obtained by repeating the synthesized waveform.

As an embodiment, the first for obtaining the second multi-period waveform
The multiple-cycle waveforms may be rearranged in sample point units, or in one or multiple cycle units or ½ cycle unit.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a flow chart showing a procedure according to an embodiment of the present invention. In the first step, a first waveform having a limited plurality of cycles is prepared. In the second step, the second plural-period waveform is obtained by rearranging the first plural-period waveform in a temporally reverse direction. In the third step, the first and second plural period waveforms are combined.

FIG. 2 shows an example of a waveform prepared or obtained in each step, and also schematically shows the tone color variation characteristics related thereto.

FIG. 2 (a) shows a first plural-period waveform prepared in the first step. In this step, for example, a multi-period waveform of a portion (sustain portion) where the tone color variation is relatively stable is selected from all waveforms from the start to the end of the desired natural musical instrument sound, and this It is advisable to perform sampling in the forward direction at a plurality of sample points M and store it in an appropriate memory. It should be noted that it is preferable to perform a level standardization process that makes the envelope level of the selected multiple-cycle waveform constant.

FIG. 2 (c) shows a second multi-period waveform obtained in the second step. In this step, for example, the first plurality of periodic waveforms stored in the memory are read out in the reverse address direction, so that the first plurality of periodic waveforms are rearranged in a temporally reverse direction on a sample point basis and phase inversion is performed. (That is, the positive and negative polarities of each sample value are inverted) to create the second plurality of periodic waveforms, which may be stored in an appropriate memory. If the temporally forward sample points in the first plurality of periodic waveforms are numbered 1-M, and the temporally forward sample points in the second plurality of periodic waveforms are numbered 1'-M ', The waveform sample value at sample point 1'is the inverted polarity of the waveform sample value at sample point M, and the waveform sample value at sample point 2'is the inverted polarity of the waveform sample value at sample point M-1. Similarly, the waveform sample value at the sample point M'is the polarity of the waveform sample value at the sample point 1 inverted. The reason for phase inversion is to prevent the cancellation of the amplitude value when the two waveforms are combined. There may be a case where there is no fear of such cancellation depending on how the waveform section is selected, but in such a case, the above-mentioned phase inversion (polarity inversion) is not necessary.

FIG. 2B shows an example of the tone color variation characteristic of the waveform shown in FIG. 2A, and FIG. 2D shows the tone color variation characteristic of the waveform shown in FIG. Since the waveform of (c) is obtained by rearranging the waveform of (a) in the opposite direction in time, the directivity of the tone color variation in both waveforms is almost opposite.

2 (e) to (g) show an example of a plurality of periodic waveforms synthesized in the third step. In the case of this example, first, the first and second plural-period waveforms shown in (a) and (c) are read from the memory and those having the same address order (for example, sample points 1 and 1 ', or 2 and 2', M
And M ', etc.) are added, and this is divided by 2 and averaged to obtain a composite waveform as shown in FIG. 2 (e). Next, appropriate start end sections A to B of the composite waveform shown in (e) are weighted by the rising characteristic envelope, and end sections C to D having the same width as the section A to B are weighted by the falling characteristic envelope. In addition, a composite waveform as shown in FIG. 2 (f) is obtained. Next, the end sections C to D of the composite waveform shown in (f) are cut out and added to the portions of the start section A to B to obtain a composite waveform as shown in FIG. 2 (g). It is preferable to store the combined waveform of (g) in the memory. FIG. 2 (h) shows a tone color variation characteristic in the waveform of (g). Since this is a characteristic obtained by combining the characteristics shown in (b) and (d), the directivity of the tone color variation is eliminated, and a substantially steady state is achieved. The timbre variation characteristics of the waveforms shown in FIGS. 2 (e) and 2 (f) also show a steady state as in FIG. 2 (h).

When a musical tone signal is generated, for example, the synthetic waveform shown in FIG. 2 (g) is repeatedly read from the memory. Thus, the second
A continuous tone signal is generated by repeating the multiple-period waveform shown in FIG. When the waveform of FIG. 2 (g) is repeated, the connection between the repeated portions can be made smooth, which is advantageous. However, in some cases, the synthesized waveform shown in FIG. 2 (e) may be stored in a memory and read out repeatedly to generate a continuous tone signal.

As another example for generating a musical tone signal, first and second
The first and second plurality of periodic waveforms stored in the memory in step 1 are repeatedly read from the memory at the same time, and the third step is executed in real time based on the repeatedly generated first and second plurality of periodic waveforms. However, by doing so, a composite waveform as shown in FIG. 2 (e) or (g) may be repeatedly generated. In addition, the first plurality of periodic waveforms stored in the memory in the first step are repeatedly read out in the forward address direction, the memory is repeatedly read out in the reverse address direction, and the second step is executed in real time. The third step may be executed in real time based on the generated first and second plural period waveforms.

As another example of the second step, the second plurality of periodic waveforms may be obtained by rearranging the first plurality of periodic waveforms in a reverse direction in time in units of one or a predetermined plurality of periods. FIG. 2 (i) shows an example of the second plurality of periodic waveforms thus obtained, which are rearranged in units of one period. That is, the first shown in FIG.
P _{1 to} P _n from the first periodic waveform to the nth (final) periodic waveform of the plurality of periodic waveforms, the first periodic waveform of the second multiple periodic waveform shown in FIG. 2 (i) is P _n. , The second periodic waveform is P _n-1 ,
...... The nth period waveform becomes P ₁ . In this case, the order of the sample points in the one-cycle waveform is not reversed in time, and therefore there is no fear of canceling the waveform at the time of synthesis and there is no need for phase inversion.

In addition, as another example of the second step, the second multiple-cycle waveform is obtained by rearranging the first multiple-cycle waveform in ½-cycle units in the opposite direction in time and performing phase inversion. May be. FIG. 2 (j) shows an example of the second multi-period waveform obtained in this way. In this case, the order of sample points in the half-cycle waveform is not reversed, but since the phase is reversed every half cycle, the problem of waveform cancellation during synthesis occurs, and therefore phase inversion (polarity inversion) occurs. I do.

Furthermore, as another example, the rearrangement process in the second step may be performed using an arbitrary number of sample points as a unit.

In the third step, the sections A to B are separated from the waveform shown in FIG. 2 (f) and added to the sections C to D to obtain a composite waveform as shown in FIG. 2 (k). The tone signal may be generated by repeating the above. In this case, as shown in Japanese Patent Laid-Open No. 59-188697, the section A to
If the starting end section of the first multiple-cycle waveform corresponding to B corresponds to the ending section of the multiple-cycle waveform of the rising section that is separately prepared, the multiple-cycle waveform of this rising section and FIG. The connection with the waveform shown in can be smoothed.

FIG. 3 shows an example of an electronic musical instrument to which the musical tone signal generating method according to the present invention is applied. In the waveform memory 10, a musical tone waveform of a rising portion and a musical tone waveform of a repeating portion which are composed of a plurality of cycles are provided for each tone color type. I remember. Here, the musical tone waveform of the repeating portion stored in the waveform memory 10 is, for example, FIG. 2 (e), (g), which is synthesized in the above-described third step,
Alternatively, the waveform is as shown in (k). For example, memory 10
How to store the waveform data for one tone color in
Sequential sample point data of the musical sound waveform of the rising portion are stored in a range from the attack start address A _s to the address immediately before the repeat start address R _s, sequential sample point data repeatedly start address of the musical tone waveform of the repeating unit R It is assumed to be stored in the range from _s to the repeated end address R _e . In this case, the coding format of the waveform data stored in the memory is not limited to the PCM (pulse code modulation) method, but may be any of the DPCM method, DM method, ADPCM method, ACM method, or the analog format. May be.

The waveform memory 10 stores the tone color selection signal TC from the tone color selection device 11.
, The tone waveforms of the rising portion and the repeating portion corresponding to the selected tone color type can be selectively read out. Each readable tone waveform sample point data is read according to the address data given to the memory 10 via the address counter 12 and the adder 13. This reading is performed by first reading all the tone waveforms of the rising portion and then repeatedly reading the tone waveforms of the repeating portion.

To describe the details below, the key press K on the keyboard 14 is detected by the key press detection circuit 15, and the key code K indicating the pressed key is shown.
C, a key-on signal KON that corresponds to the pressing and releasing of this key, and a key-on pulse that becomes a signal "1" only momentarily at the start of key pressing.
KONP is output from the circuit 15. The note clock generation circuit 16 receives a key code KC indicating a pressed key and generates a note clock pulse having a frequency corresponding to the pitch. The address counter 12 is once reset by the car-on pulse KONP at the start of sound generation, and thereafter counts the note clock pulses given from the note clock generation circuit 16. Start address generation circuit 17, in response to the tone color selection signal TC, it generates data indicating a predetermined attack start address A _s which corresponds to the tone color selected. This attack start address data and address counter 12
Is added by the adder 13 and the addition result is input to the waveform memory 10 as address data.

The repeated end address generation circuit 18 generates data indicating a predetermined repeated end address R _e corresponding to the selected tone color in response to the tone color selection signal TC. The address data output from the adder 13 and the repetitive end address data are compared by the comparator 19, and when they match each other, a signal "1" is given to the preset control input of the address counter 12. The repeated start address generation circuit 20 generates data indicating a predetermined repeated start address R _s corresponding to the selected tone color in response to the tone color selection signal TC. In this case, repeat start address data attack start address A _s and repeated start address generated from the circuit 20 R _s
It is supposed to be expressed by the difference between and. The repeat start address data generated from this circuit 20 is the address counter.
Given to 12 preset data inputs. Address counter 12 when the output signal of the comparator 19 becomes "1", i.e. when the current read address of the waveform memory 10 has reached a predetermined repeat end address R _e, repeat start address generated from the circuit 20 Preset a date. Incidentally, may be input to the comparator 19 the output of the address counter 12 as indicated by broken lines in the figure, the data representing the difference between the attack start address A _s and repeat end address if R _e circuit 18 Shall occur from.

With the above configuration, the address data supplied from the adder 13 in the waveform memory 10 in response to the key pressed, initially sequentially at a rate corresponding to the pitch of the depressed key from the attack start address AS to repeat end address R _e Along with this change, the musical tone waveform of the rising portion and the musical tone waveform of the repeating portion are continuously read from the waveform memory 10 only once. Next, the address data returns to the repeated start address R _s and sequentially changes to the repeated end address R _e , and thereafter, the change from the repeated start address R _s to the end address R _e is repeated. Along with this, the tone waveform of the repeating section is repeatedly read from the waveform memory 10.

The tone waveform data read from the waveform memory 10 is a multiplier
The envelope signal supplied to 21 and generated from the envelope generator 22 is multiplied. Envelope generator 22
Responds to the key-on signal KON, rises to a certain level at the same time when the key is pressed, maintains this certain level, and a predetermined curve corresponding to the key release (the curve corresponding to the tone color selected according to the tone color selection signal TC). ) Produces an envelope signal that decays at. The reason why the envelope signal is not provided with the attack characteristic is that the musical tone waveform of the rising portion stored in the waveform memory 10 has already been enveloped. on the other hand,
The sound is attenuated by adding a decay envelope to the tone waveform of the repeated portion that is repeatedly read. The output of the multiplier 21 is selected as an analog signal by the digital / analog converter 23, and then the sound system 24
Given to.

Although FIG. 3 shows a single music instrument, a well-known key assigner may be provided and the address counter 12 and the like may be time-divisionally operated in a plurality of channels to form a dual music instrument.

Further, in the above description, the musical tone signal is generated by repeating only one type of multiple-cycle waveform (repetition unit), but a continuous tone is generated by repeating each of the multiple types of multiple-cycle waveforms in time. The present invention can be applied to the case of generating a signal.

The configuration of FIG. 3 is merely an example, and the present invention can be applied to electronic musical instruments having various other configurations.

〔The invention's effect〕

As described above, according to the present invention, the second plurality of periodic waveforms are obtained by rearranging the first plurality of periodic waveforms in a temporally reverse direction, and the two are synthesized, and the temporal directivity of the tone color variation is obtained. Since the waveform that cancels out the above is obtained, it is possible to remove the unnatural periodicity of the tone color change in the tone signal obtained by repeating the synthesized waveform, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a flow chart schematically showing the procedure of an embodiment according to the tone signal generating method of the present invention, and FIG. 2 shows an example of a waveform prepared or obtained at each step of FIG. 1 and related thereto. FIG. 3 is a diagram schematically showing timbre variation characteristics, FIG. 3 is an electrical block diagram showing an example of an electronic musical instrument to which the musical tone signal generating method of the present invention is applied, and FIG. 4 is a diagram showing a problem to be solved by the present invention. This is a graph used as a supplement to 10 ... Waveform memory, 11 ... Tone selection device, 12 ... Address counter, 13 ... Adder, 14 ... Keyboard.

Claims (4)

[Claims] 1. A method of generating a continuous tone signal by repeating a waveform of a plurality of cycles, which comprises preparing a first plurality of cycle waveforms, and rearranging the first plurality of cycle waveforms in a temporally reverse direction. Obtaining a second plurality of periodic waveforms, combining the first and second plurality of periodic waveforms at sample points to obtain a combined multiple periodic waveform, and the combined multiple periodic waveforms Storing in memory,
And a step of generating the continuous tone signal by repeatedly reading the synthesized plural period waveforms stored in the memory. 2. When obtaining the second plurality of periodic waveforms, the first plurality of periodic waveforms are rearranged in the reverse direction in time on a sample point basis, and phase inversion is performed to perform the second plurality of periodic waveforms. The musical tone signal generating method according to claim 1, wherein a waveform is obtained. 3. When obtaining the second plurality of periodic waveforms, the second plurality of periodic waveforms are obtained by rearranging the first plurality of periodic waveforms in a reverse direction in units of one or a plurality of periods. A musical tone signal generating method as set forth in claim 1, wherein 4. In the case of obtaining the second plurality of periodic waveforms, the first plurality of periodic waveforms are rearranged in a temporally opposite direction in units of 1/2 period, and phase inversion is performed, and the second plurality of periodic waveforms are rearranged. A first aspect of the present invention for obtaining a plurality of periodic waveforms.
A method for generating a tone signal according to the item.