JP3765670B2 - Music signal generator - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a musical tone signal generating apparatus that reads a series of waveform sample groups that are stored in advance in a waveform memory and discretely represent musical tone waveforms at a speed corresponding to the pitch and outputs them as musical tone signals.
[0002]
[Prior art]
Conventionally, a series of waveform sample groups discretely representing musical sound waveforms are stored in advance in a waveform memory, and the waveform samples stored in the waveform memory are synchronized with a sampling clock signal having a relatively low fixed frequency. In order to read out, an address signal consisting of a plurality of bits specifying a waveform sample is generated at a speed corresponding to the pitch of the generated musical sound, and the vicinity of one waveform sample specified by the upper bits of this address signal And interpolating the read waveform samples using an interpolation parameter that changes according to the value of the lower bits of the address signal, and outputting the interpolated waveform samples as a musical sound signal A pitch asynchronous type musical tone signal generator configured as described above is well known.
[0003]
SUMMARY OF THE INVENTION
  The present invention pays attention to the generation of the interpolation parameter of the conventional musical tone signal generator,Have different characteristicsInterpolation is performed between two sets of interpolation parameters corresponding to two interpolation functions, and the interpolated interpolation parameters are used for interpolation of waveform samples.
[0004]
  In order to achieve the above object, the constitutional feature of the present invention is that a waveform memory storing a series of waveform sample groups discretely representing musical sound waveforms and a pitch designation signal for designating a pitch are input. Address signal generating means for generating an address signal consisting of a plurality of bits for designating waveform samples belonging to the waveform sample group, changing at a speed according to the pitch designated by the inputted pitch designation signal; Waveform sample reading means for reading out a plurality of waveform samples in the vicinity of the waveform sample specified by the upper bits of the address signal as interpolation waveform samples, control signal generating means for generating a control signal consisting of a plurality of bits, and Specified by upper bitWith two different characteristicsTwo sets of interpolation parameters that change according to an interpolation function and change according to the value represented by the lower bits of the address signal are specified, and the two specified sets of interpolation parameters according to the lower bits of the control signal Interpolation parameter generating means for generating a set of interpolation parameters and outputting them, and interpolating the read out waveform sample for interpolation using the set of output interpolation parameters, to obtain one waveform sample And waveform sample interpolation means for deriving.
[0005]
  In this case, the interpolation parameter generating means isHave different characteristicsInterpolation parameter memory for storing interpolation parameters according to a plurality of interpolation functions, and specified by upper bits of the control signal among the plurality of interpolation functionsAnd have different characteristicsInterpolation function designation means for outputting interpolation function designation data representing two interpolation functions, and designated by the interpolation function designation dataAnd two different characteristicsInterpolation parameter reading means for reading from the interpolation parameter memory two sets of interpolation parameters that change in accordance with the interpolation function of the address signal and depending on the value represented by the lower bits of the address signal, and the two sets of read out sets The interpolation parameter can be constituted by function interpolation means for interpolating the interpolation parameter with the lower bits of the control signal to generate and output a set of interpolation parameters. The control signal is, for example, a signal that varies with time.
[0006]
  In the present invention configured as described above, the waveform sample for interpolation read from the waveform memory by the address signal generating means and the waveform sample reading means is generated by the interpolation parameter generating means by the waveform sample interpolating means. Interpolated using a set of interpolation parameters. In this case, the interpolation parameter generating means is designated by the upper bits of the control signal consisting of a plurality of bits.And have different characteristicsSpecifies two sets of interpolation parameters according to two interpolation functions and changes according to the value represented by the lower bits of the address signal, and the two sets of interpolation parameters according to the lower bits of the control signal Are interpolated to generate and output a set of interpolation parameters. For example, the interpolation parameter generating means is composed of the interpolation parameter memory, the interpolation function specifying means, the interpolation parameter reading means, and the function interpolation means as described above, and the interpolation function specifying means is a control signal among the plurality of interpolation functions. Specified by the upper bits ofAnd two different characteristicsInterpolation function designation data representing the interpolation function is output, and the parameter reading means for interpolation changes according to the two interpolation functions designated by the interpolation function designation data and according to the value represented by the lower bits of the address signal Two sets of interpolation parameters are read from the interpolation parameter memory, and the function interpolation means interpolates the read two sets of interpolation parameters with the lower bits of the control signal to generate one set of interpolation parameters. Output.
[0007]
  Thus, selected according to the upper bits of the control signalDefined by functions with different characteristicsIt is possible to generate an interpolation parameter obtained by interpolating two sets of interpolation parameters with lower bits of the control signal. Therefore, according to the present invention, according to the control signalMutualTwo sets of interpolation parameters defined by different interpolation functions can be interpolated and used for waveform sample interpolation.
[0008]
【Example】
DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an entire electronic musical instrument to which a musical tone signal generator according to the present invention is applied.
[0009]
This electronic musical instrument includes a keyboard device 11 composed of a plurality of keys for designating the pitch of the generated musical tone, and a plurality of tone color selection switches 12 for selecting the tone color of the generated musical tone. The keyboard device 11 and the timbre selection switch 12 are connected to a microcomputer 13, and the computer 13 generates a waveform together with the sound source interface 14 in response to the operation of the key release / timing selection switch 12 of the keyboard device 11. The generation of each tone signal in the plurality of tone generation channels of the device 15 is controlled. Specifically, the microcomputer 13 and the sound source interface 14 have the following functions (1) to (4).
[0010]
(1) The microcomputer 13 allocates a newly pressed key to one of a plurality of musical tone generation channels in response to a key press in the keyboard device 11, and stores a corresponding to the allocated channel for the tone generator interface 14. The pitch data NN indicating the pitch of the pressed key and the key touch data KT indicating the key touch strength of the key are written in the area, and the tone of the musical tone is generated for the same assigned channel via the sound source interface 14. A key-on signal KON for instructing the start is output. In response to this, the tone generator interface 14 converts the stored pitch data NN into a frequency number FNO that increases in proportion to the key pitch frequency, and outputs it to the assigned channel together with the key touch data KT.
[0011]
(2) In response to the key release from the keyboard device 11, the microcomputer 13 searches for a musical sound signal generation channel to which the newly released key is assigned, and receives a musical sound for the same channel via the sound source interface 14. A key-off signal KOF for instructing to stop sound generation is output.
[0012]
(3) In response to the operation of the timbre selection switch 12, the microcomputer 13 stores a timbre number TC representing the timbre specified by the operated timbre selection switch 12.
[0013]
(4) The microcomputer 13 controls the tone color and volume of the tone signal based on the tone number TC, the pitch data NN, and the key touch data KT in response to pressing of the keyboard device 11 and the operation of the tone color selection switch 12. Control parameters WN, AS, LS, LE, P1 to P5, FMS, FML, FMDT, and EG are calculated and output to the assigned channel via the sound source interface 14. The control parameter WN (hereinafter referred to as waveform number WN) is used to select one of the waveform sample groups to be read out and output, and the other control parameters AS, LS, LE, P1 to P5, FMS, FML, FMDT. , EG will be described in the description of each circuit to be described later in which the same control parameter is used.
[0014]
Connected to the tone generator interface 14 are a waveform generator 15 and an envelope generator 16 having time-division channels equal to the number of musical sound generation channels. The waveform generator 15 will be described in detail later with reference to FIGS. 2 and 5. Basically, the waveform sample group designated by the waveform number WN for each time division channel corresponds to the key pitch that is depressed. The data is read out at the speed and output to the multiplier 17. The envelope generator 16 forms, for each time division channel, an amplitude envelope waveform signal that rises in response to key press and attenuates in response to key release, and outputs the signal to the multiplier 17. The attack level, attenuation coefficient, and the like that determine the shape of the amplitude envelope waveform signal are determined by control parameters EG supplied from the microcomputer 13 via the sound source interface 14.
[0015]
The multiplier 17 multiplies the waveform sample from the waveform generator 15 by the amplitude envelope waveform signal from the envelope generator for each time division channel and outputs the result to the accumulator 18. The accumulator 18 accumulates each output signal for each time division channel and supplies it to the D / A converter 21. The D / A converter 21 converts the accumulated signal into an analog signal and supplies it to the sound system 22. The sound system 22 includes an amplifier, a speaker, and the like, and generates a musical sound corresponding to the converted analog signal. As a result, the sound tone of the tone color designated by the tone color selection switch 12 is generated from the sound system 22 in response to the key release operation on the keyboard device 11.
[0016]
Next, the waveform generator 15 of FIG. 1 will be described in detail. FIG. 2 is a block diagram showing details of the waveform generator 15, and the generator 15 includes a waveform memory 31. The waveform memory 31 stores a plurality of sets of waveform samples corresponding respectively to a plurality of types of musical sound waveforms, and each waveform sample group is composed of a series of a large number of waveform samples that discretely represent a musical sound waveform having a large number of periods. . In order to save data, a large number of waveform samples in each group are divided into an attack that is read only once at the rising edge of a musical tone and a loop that is repeatedly read thereafter, and an attack of a musical sound waveform designated by the waveform number WN Start address, loop start address and end address are specified by control parameters AS (WN), LS (WN) and LE (WN), respectively.
[0017]
A value obtained by adding the integer part (upper bit) INT of the address signal ADR from the address generator 32 and the count value CNT from the interpolation counter 33 by the adder 34 is given to the waveform memory 31 as a read address signal. ing. The address generator 32 inputs the key-on signal KON, the frequency number FNO, and the control parameters AS (WN), LS (WN), and LE (WN), and sets the frequency number FNO in each time division channel for each DAC cycle. Accumulate and read the waveform sample of the attack part of the musical tone waveform specified by the waveform number WN once in response to the key-on signal KON, and then form the address signal ADR for repeatedly reading the waveform sample of the loop part (See FIG. 10). Therefore, the address signal ADR of each time division channel is a signal that changes at a rate proportional to the frequency number FNO for each predetermined period. The interpolation counter 33 outputs a count value CNT for interpolation that repeatedly changes from “0” to “5” during each time division channel timing. As a result, if the integer part INT of the address signal ADR represents the musical tone waveform sample value Y0 of FIG. 11, six waveform sample values Y from the waveform memory 31 during one time division channel timing.₀... Y5 are read for each cycle of the clock signal .phi.ab.
[0018]
The output of the waveform memory 31 is connected to a multiplier 36 via a delay circuit 35, and the multiplier 36 receives the waveform sample value Y.₀~ Y_Five6 interpolation coefficients a as interpolation parameters supplied from the interpolation coefficient generator 40₀~ A_FiveAre sequentially multiplied. The delay circuit 35 calculates the waveform sample value Y₀~ Y_FiveAnd interpolation coefficient a₀~ A_FiveAre used to adjust the output timing. Each multiplication result is supplied to and accumulated in an interpolation accumulator 37, which accumulates an interpolation coefficient a as shown in Equation 1 below.₀~ A_FiveWaveform sample value Y using₀~ Y_FiveIs interpolated to calculate and output one waveform sample value Y.
[0019]
[Expression 1]
Y = a₀Y₀+ A₁Y₁+ A₂Y₂+ A_ThreeY_Three+ A_FourY_Four+ A_FiveY_Five
The interpolation coefficient generator 40 includes an interpolation coefficient memory 41. As shown in FIG. 3, the interpolation coefficient memory 41 includes k (integer of 2 or more) interpolation coefficient tables. Each interpolation coefficient table is selected by a first interpolation coefficient selection signal FS1 from the function selection unit 42. Each interpolation coefficient table is further divided into 8 areas (however, 2 areas are not used in the present embodiment), and each area is determined by a count value CNT (0 to 5) from the interpolation counter 33. It is to be specified. In each of the six regions, each interpolation coefficient a addressed by the decimal part (lower bit) FRAC of the address signal ADR from the address generator 32 is provided.₀~ A_FiveAre stored.
[0020]
These interpolation coefficients a₀~ A_FiveIs defined by, for example, the interpolation function shown in the graph of FIG.₀~ A_FiveA plurality of waveform sample values Y by the calculation of the above equation 1 using₀~ Y_FiveIt is well known that is interpolated. In addition, according to the interpolation defined by such an interpolation function, it is well known that the waveform sample value Y as an output has an effect equivalent to that obtained by the low-pass filter processing. Changing the interpolation function from the solid line to the wavy line in FIG. 4 corresponds to setting the cut-off frequency of the low-pass filter low. The k interpolation coefficient tables include interpolation coefficients a defined by the interpolation functions having different characteristics as described above.₀~ A_FiveAre stored.
[0021]
As shown in detail in FIG. 5, the function selection unit 42 includes an aperiodic signal generator 51 and a low-frequency oscillator 52 for generating a control signal that varies with time. The aperiodic signal generator 51 receives the key-on signal KON and the control parameters P1 to P5, and outputs a first control signal FEG that changes temporally and aperiodically from the arrival of the key-on signal KON (see, for example, FIG. 6). ). In this case, the control parameter P1 represents the initial level, and the control parameters P2 to P5 represent each target level after the predetermined time of the first control signal FEG and each rate of change until the target level is reached. The signal generator 51 forms the first control signal FEG on the broken line using these control parameters P1 to P5. The low frequency oscillator 52 receives the key-on signal KON and the control parameters FMS, FML, FMDT, and outputs a second control signal LFO representing a low-frequency signal whose amplitude gradually increases with time from the arrival of the key-on signal KON ( For example, see FIG. In this case, the control parameter FMS represents the period of the second control signal LFO, the control parameter FML represents the maximum amplitude level of the signal LFO, and the control parameter FMDT is a delay from the arrival of the key-on signal KON to the generation of the signal LFO. In order to represent time, the low-frequency oscillator 52 forms the second control signal LFO using these control parameters FMS, FML, and FMDT.
[0022]
The first control signal FEG and the second control signal LFO are added by the adder 53, limited by the limiter 54 within the range of “0” to “1”, and output to the multiplier 55. The multiplier 55 multiplies the output signal of the limiter 54 by a value TN−1 obtained by subtracting “1” from the table number TN output from the first table 56 by the subtractor 57 and outputs the result. As shown in FIG. 8, the first table 56 stores the table number TN corresponding to the waveform number WN, and the table number TN is selectively read out and output by the waveform number WN. This table number TN represents the number of interpolation coefficient tables (see FIG. 3) used for the interpolation calculation of the waveform sample group designated by the waveform number WN. Therefore, the output of the multiplier 55 is a signal that continuously changes between “0” and a number smaller by “1” than the number of tables TN used. For example, if the table number TN is “4”, the output of the multiplier 55 changes between “0” and “3”.
[0023]
Of the output of the multiplier 55, the integer part (upper bit) INT is output to the second table 59 via the adder 58. The adder 58 is supplied with a clock signal φab via an inverter 58a. The adder 58 outputs the integer part INT as it is when the clock signal φab is at a high level, and the clock signal φab is at a low level. In this case, “1” is added to the integer part INT and output. As shown in FIG. 9, the second table 59 designates, for each waveform number WN, a plurality of interpolation coefficient tables (see FIG. 3) used for interpolation of the waveform sample group designated by the same number WN. A plurality of table data TD is stored. The number of table data DT for each waveform number WN is equal to the above-mentioned table number TN, and a plurality of table data TD specified by the waveform number WN is specified by the output of the adder 58 and is first to second from the second table 59. The interpolation coefficient selection signal FS1 is output.
[0024]
For example, if the waveform number WN is “1”, TD1 = 2, TD2 = 5, TD3 = 6, and TD4 = 0 are specified as the table data TD in the second table 59. On the other hand, the number of tables TN = 4 is output from the first table 56, and the integer part INT of the output signal of the multiplier 55 represents one of “0”, “1”, and “2”. , Signals representing “0” and “1”, “1” and “2”, “2” and “3” are alternately output in synchronization with the clock signal φab. Therefore, the first interpolation coefficient selection signal FS1 from the second table 59 is TD1 = 2 according to the first control signal FEG from the aperiodic signal generator 51 and the second control signal LFO from the low frequency oscillator 52. The signals TD2 = 5, TD2 = 5 and TD3 = 6, TD3 = 6 and TD4 = 0 are alternately expressed in synchronization with the clock signal φab. Then, from the interpolation coefficient memory 41 (see FIG. 3) of FIG. 2, the interpolation coefficient a in the interpolation coefficient table designated by the first interpolation coefficient selection signal FS1 is obtained.₀~ A_FiveThe interpolation coefficient a addressed by the count value CNT of the interpolation counter 33 and the fractional part FRAC of the address signal ADR.₀~ A_FiveAre sequentially output two by two in synchronization with the clock signal φab.
[0025]
Latch circuits 43 and 44 are connected to the interpolation coefficient memory 41. The latch circuits 43 and 44 are controlled by a clock signal φab and a signal obtained by inverting the signal φab by an inverter 45, and each of the two interpolation coefficients a₀~ A_FiveAre alternately latched and output to the interpolation coefficient interpolation circuit 46. The interpolation coefficient interpolation circuit 46 is supplied with the fractional part (lower bit) FRAC of the output signal from the multiplier 55 of the function selection unit 42 as the second interpolation coefficient selection signal FS2. The interpolation coefficient interpolation circuit 46 uses the second interpolation coefficient selection signal FS2, and uses a pair of interpolation coefficients a latched by the latch circuits 43 and 44.₀~ A_FiveAre interpolated (for example, two interpolation coefficients are mixed using the second interpolation coefficient selection signal FS2 as a mixing ratio), and the interpolated interpolation coefficient a₀~ A_FiveIs output to the multiplier 36.
[0026]
In the embodiment configured as described above, when any key is pressed by the keyboard device 11, the microcomputer 13 sends the pitch data NN indicating the pitch of the pressed key to the sound source interface 14. The tone generator interface 14 supplies the address generator 32 with a frequency number FNO corresponding to the pitch data NN. At the same time, the microcomputer 13 determines the waveform number WN according to the timbre number TC, the pitch data NN and the key touch data KT specified by the operation of the timbre selection switch 12, and also according to the waveform number WN. The control parameters AS, LS, LE are determined and supplied to the address generator 32. The address generator 32 designates waveform samples belonging to the waveform sample group selected by the control parameters AS (WN), LS (WN), and LE (WN), and changes at a rate proportional to the frequency number FNO. An address signal ADR consisting of bits is generated. Therefore, the tone color number TC, the pitch data NN, the key touch data KT, the waveform number WN, etc. constitute a waveform selection signal for selecting a waveform.
[0027]
The interpolation counter 33 outputs a count value CNT that repeatedly changes from “0” to “5” to the adder 34. The adder 34 adds the integer part INT of the address signal ADR and the count value CNT. Since the waveform is supplied to the waveform memory 31, the waveform sample value Y specified by the integer part INT is stored in the memory 31.₀ And the next five waveform sample values Y₁~ Y_FiveAre read as waveform samples for interpolation. Therefore, the waveform sample reading means of the present invention corresponds to the interpolation counter 33 and the adder 34.
[0028]
In the function selection unit 42, in response to the key depression, the aperiodic signal generator 51 (the control signal generating means of the present invention) is controlled by the tone number TC, the pitch data NN, and the key touch data KT. The first control signal FEG that varies with time according to the parameters P1 to P5 is generated, and the low-frequency oscillator 52 (control signal generating means of the present invention) uses the tone number TC, the pitch data NN, and the key touch data KT. A second control signal LFO corresponding to the determined control parameters FMS, FML, and FMDT is generated. On the other hand, the function selection unit 42 is also supplied with the waveform number WN determined by the tone number TC, the pitch data NN, and the key touch data KT. The multiplier 55 and the first table in the selection unit 42 are also supplied. 56, the second table 59, and the like, the interpolation coefficient memory 41 extracts the interpolation coefficient a as the interpolation parameter of the present invention.₀~ A_FiveIs supplied to the multiplier 36 through the latch circuits 43 and 44 and the interpolation coefficient interpolation circuit 46. The interpolation coefficient a is obtained by the action of the multiplier 36 and the interpolation accumulator 37.₀~ A_FiveWaveform sample value Y using₀~ Y_FiveAre interpolated and output as one waveform sample value Y. Therefore, the multiplier 55, the first table 56, the second table 59, the interpolation coefficient memory 41, the interpolation coefficient interpolation circuit 46, etc. constitute the interpolation parameter generating means of the present invention, and the multiplier 36 and the interpolation accumulator 37 are provided. This constitutes the waveform sample interpolation means of the present invention.
[0029]
As can be understood from the above description of the operation, according to the above embodiment, the waveform sample group selected by the waveform selection signal including the timbre number TC, the pitch data NN, the key touch data KT, the waveform number WN, etc. is supported. Thus, an interpolation coefficient a as an interpolation parameter used for interpolation of waveform samples belonging to the same waveform sample group₀~ A_FiveIs changed. Further, since the first control signal FEG changes with the passage of time in response to the waveform sample group representing the musical sound waveform for a plurality of periods being read out with the passage of time, the waveform sample group that changes with the passage of time is obtained. Correspondingly, an interpolation coefficient a as an interpolation parameter used for interpolation of waveform samples belonging to the same waveform sample group.₀~ A_FiveWill also be changed. Therefore, the interpolation coefficient a according to the optimum interpolation function for each waveform sample group to be read out.₀~ A_FiveEven if the waveform sample group to be read changes due to differences in timbre, key touch, pitch, etc., and the waveform sample group to be read changes as time elapses from the attack to release of the musical sound Therefore, it is possible to realize the optimum waveform sample interpolation corresponding to the change. The second control signal LFO is an interpolation coefficient a.₀~ A_FiveSince this also acts to periodically change the tone, a periodic timbre change is also realized.
[0030]
In the above-described embodiment, a plurality of types of waveform sample groups representing a musical sound waveform having a large number of cycles and varying with time are stored in the waveform memory 31. The present invention can also be applied to a musical tone signal generator in which a plurality of types of waveform sample groups to be represented are stored in the waveform memory 31. In this case, the address generator 32 is configured to generate an address signal ADR for repeatedly reading out the waveform sample group, the aperiodic signal generator 51 and the low-frequency oscillator 52 are omitted, and simply according to the waveform number WN. Interpolation coefficient a₀~ A_FiveShould be determined.
[0031]
In the above embodiment, six interpolation waveform sample values Y₀~ Y_FiveHowever, the number of waveform sample values for interpolation is not limited to six and may be other numbers. Further, the number of waveform sample values for interpolation may be selectively set in relation to connection with other circuits (for example, a digital filter), switching of the number of musical tone signal generation channels, and the like. In this case, the maximum value of the counter value CNT of the interpolation counter 33 is changed, and the channel timing is changed accordingly.
[0032]
Further, in the above embodiment, the waveform number WN is determined according to the tone color number TC, the pitch data NN, and the key touch data KT, and the interpolation coefficient a is determined according to the same number WN.₀~ A_FiveIs determined, but the interpolation function and the interpolation coefficient a in which the cutoff frequency decreases as the frequency number FNO further increases.₀~ A_FiveIs determined, it is possible to more effectively remove the aliasing noise included in the musical tone waveform signal that is finally output.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing the entirety of an electronic musical instrument to which a musical tone signal generator according to the present invention is applied.
FIG. 2 is a detailed block diagram of the waveform generator of FIG.
FIG. 3 is a memory map of the interpolation coefficient memory of FIG. 2;
FIG. 4 is a graph showing an interpolation function for defining an interpolation coefficient stored in the interpolation coefficient memory.
FIG. 5 is a detailed block diagram of a function selection unit in FIG. 2;
6 is a time chart showing an example of a first control signal output from the aperiodic signal generator of FIG.
7 is a time chart showing an example of a second control signal output from the low frequency oscillator of FIG. 5. FIG.
FIG. 8 is a table map of the first table in FIG. 5;
FIG. 9 is a table map of the second table in FIG. 5;
10 is a time chart for explaining the circuit operation of FIGS. 2 and 5. FIG.
11 is a time chart for explaining the interpolation operation of FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Keyboard apparatus, 12 ... Tone selection switch, 13 ... Microcomputer, 15 ... Waveform generator, 16 ... Envelope generator, 22 ... Sound system, 31 ... Waveform memory, 32 ... Address generator, 33 ... Interpolation counter, 36 ... multiplier 37 ... interpolation accumulator 40 ... interpolation coefficient generator 41 ... interpolation coefficient memory 42 ... function selection unit 43,44 ... latch circuit 46 ... interpolation coefficient interpolation circuit 51 ... non-periodic signal generation 52, low frequency oscillator, 56 ... first table, 59 ... second table.

Claims (3)

A waveform memory storing a series of waveform samples that discretely represent musical sound waveforms;
A plurality of pitch designation signals for designating pitches are input, and the waveform samples belonging to the waveform sample group are changed at a speed corresponding to the pitch designated by the pitch designation signal inputted. Address signal generating means for generating an address signal composed of bits;
Waveform sample reading means for reading out a plurality of waveform samples in the vicinity of the waveform sample specified by the upper bits of the address signal as interpolation waveform samples;
Control signal generating means for generating a control signal composed of a plurality of bits;
Specifying two sets of interpolation parameters that are specified by the upper bits of the control signal and that vary according to the values represented by the lower bits of the address signal according to two interpolation functions having different characteristics from each other ; Interpolation parameter generation means for generating and outputting one set of interpolation parameters by interpolating the two specified sets of interpolation parameters according to the lower bits of the control signal;
A musical tone signal generator comprising waveform sample interpolation means for interpolating the read waveform sample for interpolation using the set of output interpolation parameters to derive one waveform sample. The interpolation parameter generating means according to claim 1,
An interpolation parameter memory for storing parameters for interpolation according to a plurality of interpolation functions having different characteristics ;
Interpolation function designating means for outputting interpolation function designating data representing two interpolation functions designated by higher bits of the control signal among the plurality of interpolation functions and having mutually different characteristics ;
Two sets of interpolation parameters that are specified by the interpolation function specifying data and change according to two interpolation functions having different characteristics from each other and corresponding to a value represented by a lower bit of the address signal are stored in the interpolation parameter memory. Interpolation parameter reading means for reading from,
A musical tone signal generator comprising: function interpolation means for interpolating the read two sets of interpolation parameters with lower bits of the control signal to generate and output a set of interpolation parameters.   The musical tone signal generator according to claim 1 or 2, wherein the control signal according to claim 1 or 2 is a signal that varies with time.

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