JP2006047728A - Waveform generator and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate waveform having a complex waveform shape in a simple and abundantly controlled manner. <P>SOLUTION: Phase information, which changes with the rate corresponding to frequency information in accordance with the parameter that specifies at least two sample points, is generated so that the information is repeated along a normal direction and a reversed direction between at least the two specified sample points. The frequency information that is used for the rate with which the phase information is changed, is changed in accordance with the parameter that specifies the frequency information that sets the frequency of the waveform to be generated by at least the two sample points. By inputting the generated phase information into a waveform generating means which generates the sample data of a prescribed fundamental waveform made of a plurality of sample points, the waveform, in which the fundamental waveform is deformed in accordance with the change in the phase information, is generated. Thus, only specifying at least two sample points by a user, a waveform having a complex waveform shape is generated in a simple and abundantly controlled manner without changing pitch. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a waveform generator and a program suitable for use in generating a musical sound signal. In particular, the present invention relates to a waveform generating apparatus and a program that can generate a waveform having a complicated waveform shape by modifying a basic waveform easily and with rich controllability.

  Conventionally, as a device for generating a musical sound signal, for example, a so-called FM-type musical sound synthesizer (also referred to as an FM sound source) that synthesizes a musical sound signal having a desired harmonic structure by frequency modulation calculation (FM calculation) in the audible frequency region is known. It has been. 2. Description of the Related Art As is known in the art, an FM-type musical tone synthesizer basically generates a carrier wave signal and a modulated wave signal, and modulates the carrier wave signal with the modulated wave signal to thereby generate a musical tone signal having a desired spectrum configuration. Is generated. In general, such an FM type musical tone synthesizer includes a waveform generator called an operator capable of generating a basic waveform such as a sine wave. In this operator (waveform generator), a predetermined basic waveform (sample data) consisting of a plurality of sample points stored in advance is read out from the waveform table in accordance with phase information changing at a desired frequency corresponding to the pitch of the musical tone. The generated basic waveform is used as a carrier wave signal, a modulated wave signal, or the like for frequency modulation calculation (FM calculation).

By the way, in order to generate a musical tone signal that realizes various tone colors in the above-described FM-type musical tone synthesizer, it is preferable that the waveform shape of the carrier wave signal or the modulated wave signal is complicated. Therefore, it has been conventionally performed to control the reading of the basic waveform from the waveform table. As an example of such a device, for example, there is a musical tone synthesizer described in Patent Document 1 shown below. In the musical tone synthesizing device described in Patent Document 1, a sine stored in advance from a sine wave table (corresponding to a waveform table) while changing the phase value in a predetermined phase section by simply shifting or ignoring lower bits. A more complex musical tone signal is generated by changing the waveform shape of the sine wave by reading the sample data of the wave (corresponding to the basic waveform) and then using the waveform after the waveform shape change for frequency modulation calculation To be able to.
Japanese Patent Publication No. 6-44193

  However, as a basic waveform readout control, simply reading out the sine wave from the sine wave table while performing control such as simply shifting the phase value in the predetermined phase interval or ignoring the lower bits as described above, the original sine wave It is difficult to greatly change the waveform shape. Therefore, there is a problem that it is very difficult to generate a more complicated musical tone signal that realizes various timbres using the waveform generated in this way.

  The present invention has been made in view of the above points, and a waveform generating apparatus and a program capable of generating a waveform having a complicated waveform shape having a large change compared to a basic waveform easily and with rich controllability. Is to provide.

  The waveform generator according to the present invention is a frequency generator for generating sample data of a predetermined basic waveform composed of a plurality of sample points in accordance with input phase information, and frequency information for setting the frequency of the waveform to be generated. Means for changing at least two sample points according to a parameter, phase information generating means for generating phase information that changes at a rate corresponding to the frequency information based on the changed frequency information, and the phase Means for controlling the phase information generating means so that the phase information generated by the information generating means is repeated in the forward and reverse directions between the specified at least two sample points. By inputting the phase information generated by the means to the waveform generating means, a waveform obtained by deforming the basic waveform according to the change in the phase information can be obtained. Characterized in that it is generated from the shape generator.

  According to the present invention, phase information that changes at a rate according to frequency information according to a parameter that specifies at least two sample points is repeated in the forward and reverse directions between the specified at least two sample points. Occur. The frequency information used for the rate at which the phase information changes is obtained by changing the frequency information for setting the frequency of the waveform to be generated according to the parameter for specifying the at least two sample points. Then, by inputting the generated phase information to a waveform generating means for generating sample data of a predetermined basic waveform composed of a plurality of sample points, a waveform obtained by deforming the basic waveform in accordance with the change of the phase information Is generated. When phase information generated by repeating in the forward and reverse directions between at least two specified sample points is input to generate sample data of a predetermined basic waveform, the phase information is not changed. When input, the pitch of the waveform generated corresponding to the repetition becomes larger than the pitch of the waveform generated by inputting the phase information generated without repetition. Therefore, the frequency information is changed according to the parameter specifying the at least two sample points, and sample data of a predetermined basic waveform is generated based on the phase information that changes at a rate corresponding to the changed frequency information. In this way, the user can generate a waveform having a complicated waveform shape simply and with a high degree of controllability without changing the pitch, simply by specifying at least two sample points.

  The present invention can be constructed and implemented not only as a device invention but also as a method invention. Further, the present invention can be implemented in the form of a program of a processor such as a computer or a DSP, or can be implemented in the form of a storage medium storing such a program.

  According to the present invention, a parameter for specifying at least two sample points is newly given as a parameter, and when generating a waveform, the phase information is repeated in the forward and reverse directions between the at least two sample points. Control the occurrence of This makes it possible to easily generate a waveform having a complicated waveform shape that has a large change compared to the basic waveform, with rich controllability. Therefore, it is possible to generate various timbres using the generated waveform. An effect is obtained that a musical sound signal can be easily generated.

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

  First, a frequency modulation calculation type (FM method) musical tone synthesis apparatus to which a waveform generator according to the present invention is applied will be briefly described with reference to FIGS. FIG. 1 is a block diagram showing an embodiment of the overall configuration of a frequency modulation calculation type (FM method) musical tone synthesis apparatus to which a waveform generator according to the present invention is applied. FIG. 2 is a block diagram showing an embodiment of the basic configuration of the operator (waveform generator) shown in FIG. However, as is known in the art, an FM-type musical sound synthesizer may be equipped with one operator, which is an arithmetic unit in terms of hardware, as a waveform generator, and this one operator can be divided into two time slots. By using time-sharing, it is made to function as two operators (a modulator OM or a carrier OC described later) as shown in FIG. Therefore, in FIG. 2, only one representative operator is shown, and the operator (modulator OM or carrier OC) will be briefly described using this.

  As shown in FIG. 1, the FM musical tone synthesizer shown in this embodiment performs FM calculation using two operators (modulator OM and carrier OC) for each tone, and a musical tone signal having a desired spectrum configuration. Is synthesized. This musical tone synthesizer includes a carrier waveform generator (carrier OC) that generates a carrier waveform signal (carrier signal) that is the basis of a musical tone signal, and a modulation waveform signal (for modulating the carrier waveform signal into a desired musical tone signal). A modulation waveform generator (modulator OM) for generating a modulation wave signal). In each of these waveform generators, various parameters such as an FB (feedback) parameter, a waveform parameter, a pitch parameter, and an envelope parameter can be input, and finally output from the carrier OC according to these parameters. The waveform shape of the musical tone signal can be controlled. As will be described in detail later, in the musical tone synthesizer shown in this embodiment, at least a loop point address (LP) and a return point address (RP) as waveform parameters and appropriate relative values referred to here (for example, a relative address value) ) For each operator, and in each operator, in the address range based on the loop point address (LP) and the return point address (RP), a desired basic waveform (sine wave) is obtained from a waveform table (wave table WT described later). Etc.) is controlled so as to be read repeatedly in a round trip. By doing this, the user can simply set the loop point address (LP) and the return point address (RP) to any one of intermediate points other than the start address (SA) and end address (EA) of the basic waveform. It is possible to easily generate a musical tone signal having a more complicated waveform shape that realizes a simple timbre. Since other parameters included in the waveform parameters other than the loop point address (LP) and the return point address (RP), the FB (feedback) parameter, the pitch parameter, and the envelope parameter are well known, Description is omitted.

  As shown in FIG. 2, each operator (modulator OM or carrier OC) includes at least a selector S1, a phase generator PG, an address generator AG, a wave table WT, an envelope generator EG, an adder K1, and a multiplier J1. The When the FB parameter is set to “0”, that is, the output waveform of the operator is not self-feedback, the selector S1 does not output the self-feedback signal from the input terminal of the selector S1, while the FB parameter is “1”. That is, when the operator's output waveform is set to self-feedback, a self-feedback signal is output from the input terminal of the selector S1. That is, as shown in FIG. 1, the modulator OM has a so-called self-feedback function that performs further modulation on the output waveform by feeding back its output waveform to the input side, and the modulation is performed at the same frequency. By feeding back the output waveform, a modulated wave signal having a more complicated waveform can be generated. Therefore, whether or not to operate such a self-feedback function is controlled by setting an FB parameter. However, as can be understood from FIG. 1, since only the modulator OM has such a self-feedback function and the carrier OC does not have the above function, the carrier OC outputs a self-feedback signal. There is no. Therefore, in the carrier OC, the FB parameter is used as a parameter for determining whether or not to input an output waveform from the modulator OM.

  The phase generator PG generates a corresponding pitch frequency number according to pitch parameters such as pitch and octave information that are input in response to a user operation of a performance operator (for example, a keyboard). The pitch frequency number is a pitch frequency of a waveform to be generated corresponding to a pitch assigned in advance for each operated performance operator such as a pressed key or a key code included in performance data such as MIDI. This is frequency information composed of numerical data for determining (pitch). Although details will be described later (see FIGS. 3 and 4), when the loop point address (LP) and the return point address (RP) are set as waveform parameters in the phase generator PG, the loop point address (LP) and The generated pitch frequency number is corrected according to the return point address (RP). The pitch frequency number generated from the phase generator PG in this way is added to the output from the selector S1 by the adder K1 and given to the address generator AG.

  The address generator AG is a circuit that generates phase information corresponding to the phase angle (0 to 2π), and accumulates (may be addition or subtraction) the pitch frequency number given from the phase generator PG. In response, a waveform read address signal is generated. This waveform read address signal is address information for reading the basic waveform stored in the wave table WT. The wave table WT stores a large number of basic waveforms. In this table, waveform data for one cycle such as a sine wave, a triangular wave, and a sawtooth wave is stored as a basic waveform (sample data) for each of a plurality of sample points. ing. In the wave table WT, the absolute address storing the first sample data of the basic waveform is a start address (SA), and the absolute address storing the last sample data of the basic waveform is an end address (EA).

  In the musical tone synthesizer shown in this embodiment, as a waveform parameter, a relative value (for example, a relative value) that starts reading out the basic waveform by going back the address toward the start address (SA) (that is, in the negative direction in which the address value decreases). Loop point address (LP), which is an address value, etc., and reading back to the address are folded back, and reading of the basic waveform is started again toward the end address (EA) (that is, in the positive direction in which the address value increases). A return point address (RP) that is a relative value (for example, a relative address value) can be set as appropriate, and can be given to each operator. When each operator reads out a desired basic waveform (sample data) from the wave table WT, the loop point address (LP) and the return point address (RP) are referred to, and the loop point address (SA) is determined from the start address (SA). When the basic waveform is read sequentially until (LP) (first read), the basic waveform is read back from the loop point address (LP) to the return point address (RP) (second time). When the return to the return point address (RP) is completed, the basic waveform is read out sequentially until the end address (EA) is read again (third read). Therefore, in the address range from the loop point address (LP) to the return point address (RP), the corresponding basic waveform is repeatedly read out three times (in other ranges, only one reading is performed). The reading of the basic waveform from the wave table WT is controlled according to the address progression based on the waveform read address signal output from the address generator AG. The waveform read address signal output from the address generator AG will be described later (see FIGS. 5 and 6).

  The envelope generator EG outputs an envelope signal corresponding to the input envelope parameter, and multiplies the generated waveform by reading out the basic waveform from the wavetable WT, thereby finally outputting the envelope of the signal. To decide. In the frequency modulation calculation type musical tone synthesizer shown in FIG. 1, the signal output from the operator as described above is used as a carrier wave signal, a modulated wave signal, or the like.

  Next, details of the phase generator PG and the address generator AG included in the above-described operator will be described. First, the phase generator PG will be described with reference to FIGS. FIG. 3 is a circuit diagram showing a specific embodiment of the phase generator PG. FIG. 4 is a diagram showing an AG output waveform obtained by accumulating the pitch frequency number output from the phase generator PG as time passes (however, the offset by the start address (SA) is omitted). Here, in FIG. 4A, when the basic waveform is not repeatedly read (that is, the loop point address (LP) and the return point address (RP) are not set, the pitch frequency number described later is not corrected). 4 (b) is an AG output waveform diagram, and FIG. 4 (b) shows a case where the basic waveform is repeatedly read (that is, a loop point address (LP) and a return point address (RP) are set, and a pitch frequency described later). It is an AG output waveform diagram when the number is corrected).

ここで、「Ｌ」はウェーブテーブルＷＴにおいて１周期分の所望の基本波形を記憶しているアドレス範囲であり（つまり、スタートアドレスからエンドアドレスまでのアドレス長）、「ＬＰ」はループポイントアドレス、「ＲＰ」はリターンポイントアドレスである。 As shown in FIG. 3, the phase generator PG includes a circuit including at least a shifter B, a correction coefficient calculator E, and a multiplier J2. The shifter B is for shifting the pitch frequency number (FUNM) proportional to the pitch frequency (pitch) corresponding to the pitch input as the pitch parameter, in the same manner, according to the octave information OCT input as the pitch parameter. is there. For example, the shifter B shifts the pitch frequency number (FNUM) by the number of bits indicated by the octave information OCT and outputs it as the pitch frequency number (FNUM1). Therefore, when the octave shift is not performed, the pitch frequency number (FUNM) corresponding to the input pitch is equal to the pitch frequency number (FNUM1) after the octave shift which is the output from the shifter B. The output from the shifter B is given to the multiplier J2 and is multiplied by the correction coefficient output from the correction coefficient calculation unit E. The correction coefficient calculation unit E calculates a correction coefficient based on the loop point address (LP) and the return point address (RP) input as the waveform parameters, and supplies this to the multiplier J2, thereby outputting the pitch output from the shifter B. The frequency number (FNUM1) is corrected. The correction coefficient is calculated by the following equation (1).

Here, “L” is an address range in which a desired basic waveform for one cycle is stored in the wave table WT (that is, an address length from a start address to an end address), and “LP” is a loop point address, “RP” is a return point address.

  The correction coefficient that is output from the correction coefficient calculator E and the shifted pitch frequency number (FNUM1) that is output from the shifter B are supplied to the multiplier J2 and multiplied by the multiplier J2. Is used to calculate a corrected pitch frequency number (FNUM2) and output it to the address generator AG. As will be described in detail later, when the sample value data of the basic waveform in the wave table WT is repeatedly read according to the pitch frequency number (FNUM1) before correction between the return point address (RP) and the loop point address (LP). The pitch of the generated waveform may change accordingly (see the waveform diagram indicated by a dashed line in FIG. 6 to be described later). Here, the pitch frequency number is previously set according to the range in which the basic waveform is repeatedly read out. By correcting (FNUM1), the pitch of the waveform generated by repeatedly reading out the basic waveform from the wave table WT is prevented from changing (see the waveform diagram shown by the solid line in FIG. 6 described later).

  As shown in FIG. 4A, when the loop point address (LP) and the return point address (RP) are not given as the waveform parameters, that is, when the waveform is repeatedly read as “none”, the address described later is used. In the generator AG, a pitch frequency number (FNUM1) is sequentially added every predetermined regular time interval (Δt), and a pitch frequency number accumulated value at each time is calculated. When the loop point address (LP) and the return point address (RP) are not given, the correction coefficient by the correction coefficient calculator E is calculated as “1”, so that the pitch frequency number (FNUM1) is corrected. It is used for accumulation without any change. In the embodiment shown in FIG. 4A, the time required to reach the address length (L) of the basic waveform for one period, that is, the time required to read one period waveform from the wavetable WT is “t12”. This time corresponds to the pitch when the basic waveform is read from the wavetable WT.

  On the other hand, as shown in FIG. 4B, when the loop point address (LP) and the return point address (RP) are given as the waveform parameters, that is, when the waveform is repeatedly read out, Similarly, the pitch frequency number accumulated value at each time is calculated by sequentially adding the pitch frequency number every predetermined regular time interval (Δt), but in this case, Since the correction coefficient according to the correction coefficient calculation E is calculated as “1 or more”, the corrected pitch frequency number (FNUM2) is used for accumulation. In the embodiment shown in FIG. 4B, the relative address value “4L / 6” with respect to the address length (L) of the one-cycle waveform as the loop point address (LP) and the one-cycle waveform as the return point address (RP). Since the relative address value “L / 6” with respect to the address length (L) is set, the correction coefficient is calculated as “2” according to the above equation (1). Therefore, the pitch frequency number (FNUM2) corrected to twice the pitch frequency number (FNUM1) before correction is sequentially accumulated, which is twice as fast as the case of FIG. 4 (a). Now, the address length of one period waveform is reached. That is, the time required to reach the address length of one period waveform is “t6”, and this time corresponds to the pitch. Therefore, the pitch when reading the basic waveform from the wavetable WT is temporarily compared with the above case here. Will be changed.

  Next, the address generator AG will be described with reference to FIGS. FIG. 5 is a circuit diagram showing a specific embodiment of the address generator AG. FIG. 6 is a diagram illustrating an AG output waveform output from the address generator AG. However, in order to facilitate understanding of the explanation in FIG. 6, when the basic waveform is repeatedly read out, the case of “no correction” for the pitch frequency number is indicated by a one-dot chain line, and the case of “correction” is indicated by a solid line. The difference in the output signal depending on the presence / absence of the pitch frequency number correction in the phase generator PG described above will be described.

  The corrected pitch frequency number (FNUM2) output from the phase generator PG is given to the address generator AG, and the address generator AG receives a waveform read address signal (OUT) for reading the sample data of the basic waveform from the wave table WT. Output. Here, in order to facilitate the understanding of the description, the address generator AG will be described separately for each function for convenience. That is, if the address generator AG is functionally divided, it is based on the function X for generating the waveform read address by accumulating the pitch frequency number, the loop point address (LP), and the return point address (RP). The waveform Y can be divided into a function Y for controlling to repeatedly read out the waveform in a corresponding address range, and a circuit for realizing each of these functions is provided. The circuit that realizes the function X includes at least selectors S2 and S3, a delay circuit D, a gate circuit G, an adder K2, and a subtractor M. On the other hand, the circuit for realizing the function Y includes at least an inverter P, a selector S2, comparison circuits H1 and H2, delay circuits D1 and D2, EXOR circuits O1 and O2, OR circuits N1 and N2, a counter CN, and a decoder Q. It consists of Of course, it goes without saying that the circuits for realizing the function X and the function Y are not limited to those described above.

  First, a circuit for realizing the function X will be described. The corrected pitch frequency number (FNUM2) output from the phase generator PG is given to the selector S2. The selector S2 outputs the given pitch frequency number (FNUM2) as it is when the input signal from the decoder Q described later is “0”, and the input signal from the decoder Q described later is “1”. The pitch frequency number (FNUM2) obtained by inverting the sign of the given pitch frequency number (FNUM2) by the inverter P is output to the adder K2. Since the operation of the decoder Q (setting of the input signal “0” or “1”) will be described later, a description thereof is omitted here. The adder K2 includes an output from the selector S2 (either the pitch frequency number (FNUM2) or the pitch frequency number (FNUM2) whose polarity is reversed), a delay circuit D, a subtractor M, a selector S3, and a gate circuit G. The accumulated value of the pitch frequency number (FNUM2) is calculated by adding the output from the circulation circuit consisting of Here, the pitch frequency number (FNUM2) is corrected after being proportional to the pitch assigned to the pressed key or the pitch frequency (pitch) corresponding to the key code included in the performance data such as MIDI. It is numerical data and corresponds to a phase increment value per unit time. Therefore, the accumulated value obtained by repeatedly calculating the pitch frequency number (FNUM2) at regular time intervals (Δt) is phase information that changes with time, and this is the basic waveform for one period stored in the wave table WT. Corresponds to a relative address in the storage area. The accumulated value of the pitch frequency number (FNUM2) calculated by the adder K2 is given to the delay circuit D, the subtracter M, and the comparison circuits H1 and H2 of the circulation circuit.

  In the circulation circuit including the delay circuit D, the subtractor M, the selector S3, and the gate circuit G, the accumulated value of the pitch frequency number (FNUM2) is delayed by one sampling period in order to accumulate the pitch frequency number (FNUM2). To the adder K2. That is, the delay circuit D gives the pitch frequency number accumulated value calculated at the time delayed by the time (Δt), which is one sampling period output from the adder K2, to one input terminal of the selector S3. A value other than the most significant bit (MSB) of the data output from the subtractor M is given to the other input terminal of the selector S3. The subtractor M subtracts the address length (L) from the pitch frequency number accumulated value output from the adder K2. In the selector S3, when the most significant bit (MSB) of the data output from the subtractor M is “1”, other than the most significant bit (MSB) is output to the gate circuit G, and the most significant bit (MSB) ) Is “0”, the pitch frequency number accumulated value output from the delay circuit D is output to the gate circuit G. In this way, when the pitch frequency number accumulated value overflows, accumulation is performed again from the minimum value, so that a waveform having a repetition period is output as the waveform read address signal output from the address generator AG. . In the gate circuit G, the pitch frequency number accumulated value is supplied to the adder K2 until a key-on pulse (KONP), which is a pulse signal generated with key-on, is newly input. When a key-on pulse (KONP) is newly input, the pitch frequency number accumulated value is not given to the adder K2, so that a new one is newly generated based on the pitch frequency number of the pitch associated with the key-on key. Accumulation of pitch frequency number starts from the beginning. The adder K2 adds the newly input pitch frequency number (FNUM2) and the pitch frequency number accumulated value from the gate circuit G.

Next, a circuit for realizing the function Y will be described. The return point address (RP) and the loop point address (LP) are respectively added to the input terminals of the comparison circuits H1 and H2. Further, a pitch frequency number accumulated value (relative address signal), which is an output from the adder K2, is added to the other input terminals of the comparison circuits H1 and H2. The output of the comparison circuit H1 that compares the return point address (RP) with the pitch frequency number accumulated value is applied to one terminal of the OR circuit N1 via the delay circuit D1 and the EXOR circuit O1. On the other hand, the output of the comparison circuit H2 that compares the loop point address (LP) with the pitch frequency number accumulated value is applied to the other terminal of the OR circuit N1 via the delay circuit D2 and the EXOR circuit O2. The output of the OR circuit N1 is given to the counter CN, and the counter CN sends a counter value, which is the result of counting according to the output from the OR circuit N1, to the decoder Q. As shown in FIG. 4, when the return point address (RP) and the loop point address (LP) are given, the decoder Q has a counter value “2” or “3” from the counter CN. "1" is output to the selector S2, otherwise "0" is output to the selector S2. The counter value for determining “0” or “1” output from the decoder Q to the selector S2 is an example. How to give a return point address (RP) and a loop point address (LP), a pitch frequency number It goes without saying that the counter value may be different depending on the size of (FNUM2) or the relationship between them.
The counter CN is supplied from an OR circuit N2 that receives the most significant bit (MSB) of the data output from the subtractor M and a key-on pulse (KONP) that is a pulse signal generated upon key-on. Is reset to “0”.

  First, when a key-on pulse (KONP) is input to the OR circuit N2 in response to the key-on, a reset signal is applied to the counter CN by the OR circuit N2, so that the count value becomes “0”. Is also “0”. Then, the selector S2 selects the input pitch frequency number (FNUM2), and the addition of the pitch frequency number (FNUM2) is started. That is, when a key-on pulse (KONP), which is a pulse signal generated with key-on, is newly input to the OR circuit N2, the newly input positive and negative pitch frequency is not reversed from that point. Accumulation starts according to the number (FNUM2). When the pitch frequency number accumulated value (relative address signal) reaches the return point address (RP) (first arrival), the EXOR circuit O1 becomes “1” and the EXOR circuit O2 becomes “0”. The OR circuit N1 becomes “1”, and the counter CN counts the count value from “0” to “1”. Since the decoder Q outputs “0” in response to the count value “1”, the selector S2 performs pitch pitch so that the pitch frequency number (FNUM2) continues to be added to the pitch frequency number accumulated value (relative address signal). Select the frequency number (FNUM2). Here, after the pitch frequency number accumulated value (relative address signal) reaches the return point address (RP) for the first time, “1” is always output by the comparison circuit H1, and accordingly, EXOR is output. The circuit O1 always outputs “0” to one terminal of the OR circuit N1.

  When the pitch frequency number accumulated value (relative address signal) reaches the loop point address (LP) (first arrival), the output signal of the decoder Q is changed from “0” to “1”. That is, when the first loop point address (LP) is reached, the EXOR circuit O2 becomes “1”, and since the EXOR circuit O1 always outputs “0” as described above, the OR circuit N1 Becomes “1” and the counter CN counts the count value from “1” to “2”. The decoder Q outputs “1” according to the count value “2”. Therefore, the selector S2 selects the pitch frequency number (FNUM2) whose polarity is inverted by the inverter P. Therefore, after the pitch frequency number accumulated value (relative address signal) reaches the first loop point address (LP), the pitch frequency number accumulated value is subtracted. Then, when the pitch frequency number (FNUM2) is newly input and the first subtraction of the pitch frequency number accumulated value is started, in this embodiment, the EXOR circuit O1 outputs “0” as described above. Since the EXOR circuit O2 remains “1”, the OR circuit N1 becomes “1” and the counter CN counts the count value from “2” to “3”. Further, the count value “3” does not change until the pitch frequency number accumulated value (relative address signal) that has been subtracted reaches the return point address (RP) again (second arrival). The decoder Q outputs “1” according to the count value “3”. Therefore, during the count value “3”, that is, from when the first subtraction is started until the pitch frequency number accumulated value reaches the return point address (RP) again (second arrival), the pitch frequency number accumulated. The value will be subtracted.

  When the pitch frequency number accumulated value (relative address signal) thus subtracted reaches the return point address (RP) again (second arrival), the output signal of the decoder Q changes from “1” to “0”. Be changed. That is, when the second return point address (RP) is reached, the EXOR circuit O1 changes from “0” to “1”, and the EXOR circuit O2 remains “0”. The counter CN counts the count value from “3” to “4”. The decoder Q outputs “0” according to the count value “4”. Therefore, the selector S2 selects the pitch frequency number (FNUM2). Therefore, after the pitch frequency number accumulated value (relative address signal) that has been subtracted reaches the return point address (RP) again, the pitch frequency number (in which the sign frequency is not reversed with respect to the pitch frequency number accumulated value ( FNUM2) is added again. Then, when a new pitch frequency number (FNUM2) is input and the first addition of the pitch frequency number accumulated value is started again, in this embodiment, the EXOR circuit O1 remains "1" and EXOR Since the circuit O2 remains “0”, the OR circuit N2 becomes “1”, and the counter CN counts the count value from “4” to “5”. The count value “5” does not change until the pitch frequency number accumulated value (relative address signal) reaches the loop point address (LP) again (second arrival). Since the decoder Q outputs “0” according to the count value “5”, the pitch frequency number accumulated value is added during the count value “5”.

  Next, when the pitch frequency number accumulated value (relative address signal) reaches the loop point address (LP) again (second arrival), the output signal of the decoder Q is “0” unlike the first arrival. "" Is not changed from "1" to "1" and remains "0". That is, when the second loop point address (LP) is reached, the EXOR circuit O1 is “0” and the EXOR circuit O2 is “1”, so that the OR circuit N1 becomes “1” and the counter CN Counts the count value from “5” to “6”. The decoder Q outputs “0” according to the count value “6”. That is, unlike the first arrival, the selector S2 does not select the pitch frequency number (FNUM2) whose polarity is inverted by the inverter P at the second arrival. Therefore, after the pitch frequency number accumulated value (relative address signal) reaches the second loop point address (LP), the pitch frequency number (FNUM2) whose polarity is not reversed with respect to the pitch frequency number accumulated value. ) Is added as it is. When “1” is given as the most significant bit (MSB) of data from the subtracter M, the count value of the counter CN is reset to “0”.

  As described above, the pitch frequency number accumulated value generated by sequentially adding the input pitch frequency number (FNUM2) at regular time intervals is a memory storing a basic waveform for one period. Corresponds to a relative address within the region. In order to read the basic waveform from the wave table WT, it is necessary to convert the pitch frequency number accumulated value (relative address signal) into an absolute address signal. Therefore, the adder K3 converts the pitch frequency number accumulated value (relative address signal) into an absolute address signal by adding the start address (SA) which is an absolute address. By accessing the wave table WT according to the absolute address signal output from the adder K3, the sample data of a predetermined basic waveform (for example, a sine wave) stored in the wave table WT responds to the wave table WT. Is read from.

  In this way, the address generator AG generates a waveform read address signal by repeatedly calculating and accumulating the pitch frequency number (FNUM2) at regular time intervals. As shown in FIG. 6, when a loop point address (LP) and a return point address (RP) are given as waveform parameters, first, reading of sample value data is started from the start address (SA) at time “t0”. The Each predetermined regular time interval is incremented by an address corresponding to the pitch frequency number (FNUM2), but from the time “t4” when the address value reaches the loop point address (LP), the predetermined regular time is reached. For each interval, the address corresponding to the pitch frequency number (FNUM2) is subtracted. From the time “t7” when the address value reaches the return point address (RP), until the address length (L) is reached by an address corresponding to the pitch frequency number (FNUM2) every predetermined regular time interval. Will be increased. In this way, a waveform read address signal consisting of an absolute address for reading one period waveform is generated. In this case, the time until the address length (L) of the one-cycle waveform is reached is “t12”, and the input pitch frequency number (FNUM1) before correction is used as the address as it is (see FIG. 4A). Are read at the same pitch. That is, by correcting the pitch frequency number in advance in the phase generator PG, the same pitch is maintained in the waveform generated by repeatedly reading out the waveform.

  As described above, when the basic waveform is read from the wave table WT according to the waveform read address shown in FIG. 6, for example, output from the address generator AG, a waveform having the waveform shape shown in FIG. 7 can be generated. it can. FIG. 7 is a diagram illustrating an example of a waveform generated when a sine wave is read from the wave table based on the AG output waveform illustrated in FIG. As can be understood from FIG. 7, as described above, output is performed by performing waveform readout control so as to repeatedly read out the basic waveform between the loop point address (LP) and the return point address (RP). Only the waveform shape can be changed without changing the waveform pitch. Accordingly, the user can read the basic waveform by changing the waveform shape of the original basic waveform by appropriately setting the loop point address (LP) and the return point address (RP). By using the obtained waveform for frequency modulation calculation, it is possible to easily generate a musical tone signal having a more complicated waveform shape that realizes various tone colors. In this manner, the modulator OM shown in FIG. 1 generates a modulated wave signal by reading the basic waveform from the wave table WT according to the pitch frequency number accumulated value. On the other hand, in the carrier OC, a carrier wave signal is generated by reading out a basic waveform from the wave table WT according to the accumulated pitch frequency number, and the modulated wave signal output from the modulator OM and the generated carrier wave signal are added. A modulated tone signal can be output.

In the embodiment described above, the corresponding basic waveform is repeatedly read out in a loop once in the address range from the loop point address (LP) to the return point address (RP) given as a waveform parameter. The number of loops for reading may be given as a waveform parameter. In such a case, when correcting the pitch frequency number, the correction coefficient is calculated considering not only the loop point address (LP) and return point address (RP) but also the number of loops, thereby temporarily changing the pitch. Try to keep it.
In the above-described embodiment, the relative address value of the two points of the loop point address (LP) and the return point address (RP) is given as a waveform parameter, and the basic waveform is repeatedly read between them. . For example, three relative address values (for example, A1 <A2 <A3) are given as waveform parameters, and after proceeding from address A1 to address A3, proceed in the reverse direction from address A3 to address A2, and again from address A2 to address A2. The basic waveform may be repeatedly read by proceeding to A3. Alternatively, four relative address values (for example, A1 <A2 <A3 <A4) are given as waveform parameters, and after proceeding from address A1 to address A4, proceeding in the reverse direction from address A4 to address A2, and then address A2 After proceeding from address A3 to address A3, the basic waveform is repeatedly read by proceeding in the reverse direction from address A3 to address A2 (or address A1) and again from address A2 (or address A1) to address A4. Also good. By doing this, it is possible to generate a waveform having a more complicated waveform shape by simply reading the basic waveform from the wave table WT. Of course, even in such a case, it is needless to say that the correction coefficient is calculated in consideration of repetition and the pitch is temporarily changed by this.
Of course, in the case described above, the circuit for realizing the function Y for performing the control of repeatedly reading the basic waveform in the address range shown in FIG. 5 in the corresponding address range should be changed in accordance with each of the above embodiments. Needless to say, is necessary.

In the above-described embodiment, the simplest frequency modulation calculation of one term is performed using two time slots and one operator (calculation unit) is performed in a time division manner. However, the present invention is not limited to this. An operator may be prepared, and an FM calculation algorithm may be selected by selectively switching the connection mode of each operator to synthesize a musical tone having a desired tone color.
Needless to say, the basic configuration of the operator (see FIG. 2) and the circuit configuration of the phase generator PG or the address generator AG (see FIG. 3 or FIG. 5) shown in the above-described embodiments are merely examples. Yes.
It goes without saying that the sample value data of the basic waveform stored in advance in the storage device may be of any waveform sample data system such as PCM, DPCM, ADPCM.
In the above-described embodiment, an example in which the generated waveform is used in a frequency modulation arithmetic type (FM method) musical sound synthesizer has been described. It may be used as a signal or a modulated wave signal.

1 is a block diagram showing an example of the overall configuration of a frequency modulation arithmetic type musical tone synthesizer to which a waveform generator according to the present invention is applied. It is a block diagram which shows one Example of the basic composition of an operator (waveform generator). It is a circuit diagram which shows the specific Example of a phase generator. FIG. 4A is a diagram showing an AG output waveform obtained by accumulating the pitch frequency number output from the phase generator with time. FIG. 4A shows a case where there is no repeated reading, and FIG. Is the case. It is a circuit diagram which shows the specific Example of an address generator. It is a figure showing AG output waveform output from an address generator. It is a figure showing an example of the waveform produced | generated when a sine wave is read from a wavetable based on AG output waveform shown in FIG.

Explanation of symbols

OM ... operator (modulator), OC ... operator (carrier), S1 (S2, S3) ... selector, PG ... phase generator, AG ... address generator, EG ... envelope generator, WT ... wavetable, K1 (K2, K3) ... Adder, J1 (J2) ... multiplier, B ... shifter, E ... correction coefficient calculator, H1 (H2) ... comparison circuit, N1 (N2) ... OR circuit, O1 (O2) ... EXOR circuit, CN ... counter, Q: Decoder, D (D1, D2): Delay circuit, G: Gate circuit, P: Inverter, M: Subtractor

Claims (5)

Waveform generation means for generating sample data of a predetermined basic waveform composed of a plurality of sample points according to input phase information;
Means for changing frequency information for setting a frequency of a waveform to be generated according to a parameter specifying at least two sample points;
Phase information generating means for generating phase information that changes at a rate corresponding to the frequency information based on the changed frequency information;
Means for controlling the phase information generation means so that the phase information generated by the phase information generation means is repeated in the forward and reverse directions between the identified at least two sample points. By inputting the phase information generated by the information generating means to the waveform generating means, a waveform obtained by deforming the basic waveform according to the change of the phase information is generated from the waveform generating means. Waveform generator.   The waveform generating apparatus according to claim 1, wherein positions of the at least two sample points can be changed according to the parameter.   The waveform generator according to claim 1, wherein the number of repetitions in the forward and reverse directions can be changed.   A modulation calculation type musical tone synthesizer using the waveform generator according to claim 1 as means for generating a waveform of at least one of a modulated wave and a carrier wave. On the computer,
A procedure for generating sample data of a predetermined basic waveform consisting of a plurality of sample points according to input phase information,
A procedure for changing frequency information for setting a frequency of a waveform to be generated according to a parameter for specifying at least two sample points;
A procedure for generating phase information that changes at a rate according to the frequency information based on the changed frequency information;
A program for executing a control procedure so that the generated phase information is repeated in the forward and reverse directions between the specified at least two sample points.

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