JP2679042B2 - Input waveform signal controller - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an input waveform signal control device used in, for example, an electronic guitar, and in particular, a sound based on a pitch (fundamental frequency) extracted by an input waveform signal from the outside. Regarding what determines high. BACKGROUND OF THE INVENTION Conventionally, a pitch (fundamental frequency) is extracted from a waveform signal generated by a performance operation of a natural musical instrument, and a sound source device composed of an electronic circuit is controlled to artificially influence a musical sound or the like. A variety of such methods have been developed. In this type of electronic musical instrument, it is common to extract the pitch of an input waveform signal and then instruct the sound source device to generate a sound having a pitch name corresponding to the pitch. In this case, in order to convert the extracted pitch data T into the corresponding pitch name data K, if the pitch data of the reference pitch name K ₀ is T ₀ , T ₀ / T = 2 ^{K / 12/2 k0 /} There are ¹² relationships, and based on this, the note name data K is obtained by the logarithmic expression of K = K ₀ + 12log ₂ (T ₀ / T). However, since this logarithmic calculation takes a long processing time, there is a problem with an electronic musical instrument that has to generate and emit a musical tone of a pitch corresponding to the waveform as soon as the waveform is input. . Therefore, the pitch data for a plurality of typical note name data is stored, the one closest to the extracted pitch data is searched from this pitch data, and interpolation calculation is performed if necessary, thereby It is considered to get a name. According to this, when attempting to cover a wide range of notes over multiple octaves or to improve accuracy, the memory capacity of the data table for searching note names becomes extremely large, and the time required for searching is long. There was a problem that it would become. [Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide an input waveform signal control device capable of searching a pitch name with high accuracy over a wide range with a small memory capacity. To provide. SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention divides a range of one octave into a plurality of ranges, and the difference pitch data dTm in which each of the divided ranges is represented by a pitch difference.
And order data m set in order of pitch magnitude with respect to the difference pitch data dTm, reference pitch data T ₀ corresponding to the lowest pitch in the octave range,
After searching the octave OCT corresponding to the pitch extraction data and the range below the octave by the pitch name data K ₀ corresponding to the reference pitch data T ₀ , the fractional data t below the octave is obtained by dividing the range of one octave. To determine the note name data K to be obtained after searching which one of the plurality of note ranges it belongs to, It is possible to obtain the pitch value of the corresponding pitch name by the expression of. As a result, it is not necessary to store pitch data over a wide range of pitches for which note names are to be determined, the memory capacity can be reduced accordingly, and the width of the pitch data stored can be made smaller as much as the memory capacity can be reduced. It is possible to improve the accuracy of determining the note name. [Embodiment] In this embodiment, the pitch extraction circuits P1 to P6 serve as pitch extraction means, the pitch data table 40 serves as pitch data storage means, the CPU 100 which executes steps D1 to D7 serves as octave determination means, and steps D8 to D12. The CPU 100 that executes the steps corresponds to the pitch name determining means. 1. Overall Circuit Configuration FIG. 1 shows the overall circuit configuration of the embodiment.
The signals of the two input terminals 1 are signals from pickups provided on each of the six strings stretched on the electronic guitar body and converting vibrations of the strings into electric signals. The tone signal from the input terminal 1 is a pitch extraction circuit P1
... P6 (only the first string P1 is shown in the figure). Each of the amplifiers 2... Within the amplifier is amplified by a low-pass filter (LPF) 3. Is extracted and the maximum peak detection circuit (MAX)
4,..., A minimum peak detection circuit (MIN) 5 and a zero cross point detection circuit (Zero) 6. The low-pass filter 3... Is 4 of the vibration sound frequency f of the open string of each string.
The cutoff frequency is set to 4f times. this is,
This is based on the fact that the frequency of the output sound of each string is within two octaves. The maximum peak detecting circuit 4 detects the maximum peak point of the tone signal, and the flip-flops 14 connected at the subsequent stage at the rise of the detected pulse signal.
… The Q output becomes High level and this flip-flop
The AND output of the output of 14... And the inverted output of the inverter 30 of the zero-crossing point detection circuit 6.
… Via CPU 100 as interrupt command signals INT _{a1 to} INT _a6
Similarly, the minimum peak detection circuit 5 also detects the minimum peak point of the tone signal, and the flip-flop 15 connected to the subsequent stage at the rise of the detected pulse signal.
… The Q output becomes High level and this flip-flop
15 and the output of the output of ... and the output of the zero-crossing point detecting circuit 6 ... is given to the CPU100 as an interrupt command signal INT _b1 to INT _b6 through the AND gates 25 ..... That is, the maximum peak point is detected and the flip-flop 14
Is high level, when the waveform crosses from positive to negative, the interrupt command signals INT _{a1 to} INT _a6 are given to the CPU100, conversely the minimum peak point is detected and the flip-flop 15 becomes high level. When the waveform changes from negative to positive, the interrupt command signals INT _{b1 to} INT _b6
To enter. Then, immediately after receiving these interrupt command signals, the CPU 100 sets the corresponding flip-flops 14..., 15.
Then, clear signals CL _{a1 to} CL _a6 and CL _{b1 to} CL _b6 are generated and reset. Therefore, no matter how many times the zero-cross point is detected until the next maximum peak point or minimum peak point is detected, the corresponding flip-flops 14..., 15. Become. Then, in the CPU 100, the interruption command signal INT _{a1 to} INT _a6 or INT _{b1 to} INT _b6 is given by the vibration output of the string, and the pitch of the pitch according to the pitch data of at least one of the time intervals is given. To occur. It should be noted that at the start of sound generation, a tone having an open string pitch may be started and corrected to a correct frequency after pitch extraction. The operation at the start of sound generation will be described later. Then, the pitch data of the above time interval is obtained using the counter 7 and the work memory 101 as described later. That is, the work memory 101 stores various data such as the count value of the counter 7 at the time of the zero crossing point immediately after the maximum peak point or immediately after the minimum peak point. On the other hand, the pitch data table 40 is dTm and m in FIG.
As indicated by and, pitch data K “57.0” “57.5” “58.0” “58.5” ... and corresponding pitch data T “4525” “from the pitch of A _{3 to} the pitch of A ₄ 4271 '', 4149 ''
"4031" ... is stored as a difference value expression. In other words, the pitch data “57.0” of A ₃ and its pitch data “452
“5” is used as reference data when pitch data is determined from pitch data as K ₀ and T ₀ . Then, in the pitch data table 40, the pitch data dTm “129” “125” “12” of the differential expression representing the difference of each pitch data T “4525” “4271” “4149” “4031” ....
2 ”…… and the corresponding order data m“ 0 ”“ 1 ”
“2”, “3”, and so on are stored. As a result, the pitch data K is increased or decreased by "0.5" every 50 cents beyond the octave range, and the belonging octave and pitch name can be known based on the value of the pitch data K. Based on each data of this pitch data table 40,
The pitch data K is obtained from the extracted pitch data T,
To obtain this, first, the extracted pitch data T is multiplied by 2 ⁿ (n =
..., 2, as -1,0,1,2 ....), and to enter the range T ₀ through T _0/2 of the pitch data T of A ₃ to A _4, the value of n in this case Octave of extracted pitch data based on
The OCT is determined, and then the difference pitch data dT is calculated from the fractional data less than the octave, which is the difference between the extracted pitch data multiplied by 2 ⁿ and the reference pitch data T _{0 of} A _3.
The pitch name is determined by sequentially subtracting m, and the corresponding order data m when it is no longer possible to draw. Then, a finer pitch data portion (for example, a cent unit) is obtained by proportional interpolation between the last remaining data t and the difference pitch data dTm drawn immediately before. After the start of sound generation, the frequency of the musical tone being generated is variably controlled according to the pitch data that is sequentially obtained. That is
The data designating the pitch obtained as described above is sent from the CPU 100 to the frequency ROM 8, and as a result, the frequency data indicating the corresponding frequency is read out and sent to the string circuit 9 to generate a tone signal. Sound is output from the sound system 10. Further, the tone signal from the low pass filter 3 ... Is given to the A / D comparator 11 ... And converted into digital data according to the waveform level. The output of the A / D converter 11 is a latch 12
…… is latched. The latch signal for the latches 12 is generated by the outputs of the flip-flops 14..., 15... Passing through the OR gates 13. Stores a signal indicating the level of the waveform at that time. The latch signals L _{1 to} L ₆ from the OR gates 13...
Also given to the U100. The outputs of the latches 12 are supplied to the CPU 100, and the control of the start and stop of sound generation, and the sound emission level (volume) of the output sound is performed according to the data. Note that this latch 12
The peak value that is the peak value stored in
Sequentially written to 1. That is, in the CPU 100, when the absolute value of the data indicating the waveform level given by the A / D converter 11 becomes equal to or more than a predetermined constant value, the CPU 100 starts generating a tone and extracts a pitch (basic frequency). When this data falls below a certain value, a mute instruction is issued and sound emission is terminated. Details of the operation are as described later. In FIG. 1, the A / D converter 11 is provided independently for each of the pitch extraction circuits P1 to P6, but it is of course possible to use one A / D converter in a time-division manner. The frequency ROM 8 and the tone generator 9 form a tone generation system of at least six channels by time division processing. FIG. 2 shows a time chart of signal waveforms at various parts in the pitch extraction circuit P1, in which the output of the low-pass filter 3, the output of the maximum peak detection circuit 4, and the minimum peak detection circuit 5 are shown. , The output of the zero-cross point detection circuit 6, and the interrupt command signals INT _{a1 to} INT a
_a6, is an interrupt command signal INT _b1 ~INT _b6. Operation Next, the operation of this embodiment will be described. Figure 3 shows CPU1
FIG. 4 is a main flow of 00, FIGS. 4 and 5 are a flow of an interrupt routine, and FIG. 6 is a flow of a pitch calculation process. It should be noted that although FIGS. 3 to 6 only show the processing for one string, the processing for all strings is exactly the same, so assuming that the CPU 100 executes the processing for each string in a time division manner. Good. Main Processing In the main routine (FIG. 3), the CPU 100 first performs initial setting in step A1, then reads the value of the A / D converter 11 from the latch 12 in step A2, and unless a certain level is reached, a musical tone is generated. Off processing continues (step A3,
A4). Now, if there is a string playing operation and a tone signal of a certain level or higher as shown in FIG. 2 is input to the A / D converter 11 (step A3), the process proceeds to step A5 and the frequency control process, that is, the counter 7 is performed. Performs the tone emission processing that gives the data from the frequency ROM8 to the frequency ROM8, and continues this tone emission processing as long as the tone signal level is above a certain level (step A2,
A3, A5). The count data of the counter 7 is set in the interrupt processing described below. Interrupt processing at the zero-cross point Next, the musical sound waveform rises by the string operation,
When the waveform level reaches the first maximum peak point shown in MAX1, the maximum peak detection circuit 4 generates a signal as shown in FIG. 2, and the flip-flop 14 is set to the high level. From the zero-cross point detection circuit 6 shown in FIG.
A zero-cross point detection output is inverted in terms of zero1 (see drawing), the interrupt command signal INT _a is supplied to the CPU 100 from the AND gate 24, CPU 100 starts the interrupt processing of FIG. 4. First, the CPU 100 reads the count value of the counter 7 in step B1, and determines whether or not the waveform is the first waveform (step B2). Now, the tone waveform has just risen,
Since it is the first wave, the routine proceeds to step B6, the flag "1" is set, and the count value of the counter 7 read at step B1 is set in the work memory 101. This flag "1"
Is a flag indicating that the zero-cross point next to the maximum peak point has already been detected. If this flag is cleared, it indicates that the minimum peak point has been detected. The function of this flag is as described later. Next, when the minimum peak point indicated by MIN1 in FIG. 2 is reached, the peak detection signal is output from the minimum peak detection circuit 5, and the flip-flop 15 is set. Then, at the next zero crossing point (Zero2), the output of the zero crossing point detection circuit 6 is inverted, and as a result, the AND gate 25 outputs CP.
U100 interrupt command signal INT _b is given to, CPU 100 starts the interrupt processing of FIG. 5. First, the CPU 100 resets the flip-flop 15 in step C1, reads the count value of the counter 7 and determines whether the waveform is the first wave (step C2), but the zero cross point next to the minimum peak point is now In case of, it is the first wave, so step C6
Go to and clear the flag to "0", and work memory
In 101, the count value of the counter 7 read in step C1 is set. Whether or not it is the first wave in the step B2 of the step C2 is determined by setting the first wave flags A and B when the waveform level data from the A / D converter 11 becomes a certain level or more, for example.
Before step B6 after step B2 when the interrupt command signal INT _a zero-cross point detection immediately after the maximum peak point is given, clears the first wave-th flag A, the zero-cross point detection immediately after the minimum peak point before step C6 after step C2 when the interrupt command signal INT _b is given, it clears the first wave-th flag B, whether the step B2, C2 in first wave-th flag a, B is standing It is achieved by judging. Then, upon reaching the zero-cross point following the maximum peak point shown in MAX2 of FIG. 2 (ZOer3), the interrupt command signal INT _a zero-cross point detection immediately after the maximum peak point is given, CPU 100 counts of counter 7 in step B1 The value is read, it is determined in step B2 that the waveform is not the first waveform, and it is determined in step B3 whether the flag is "0".
The flag is set to "0" at the next zero cross point (Zero2) of the immediately preceding minimum peak point MIN1, so the CPU 100 proceeds to step B6 and immediately after the maximum peak point MAX1 one cycle before the zero cross point (Zero1). Read the time count data set in the work memory 101 with and subtract it from the current time count data read in step B1 above
Pitch data T for one cycle from 0 to Zero3 is extracted. Then, the pitch data K is calculated from the extracted pitch data T based on the data content of the pitch data table 40 (step B5). The details of this calculation will be described later.
As a result, in the above step A5, the pitch data K is given to the frequency ROM8 so that the musical tone of the frequency having the time length from the zero cross point (Zero1) to the zero cross point (Zero3) as one cycle is emitted. Will be in control. Subsequent to the above processing, the CPU 100 sets the flag "1" and sets the current time count data value in the work memory 101 (step B6). Thus, in steps C6 and B3, the zero cross point immediately following the maximum peak point is determined, the time between these zero cross points is measured, and in steps B4 and B5, the period calculation and the pitch calculation are performed. Similarly, the zero-cross point (Zero
In response to the input of the interrupt signal INT _b from the AND gate 25 generated by the detection of 4), the CPU 100 performs the processing of the flow shown in FIG. 5, this time, the previous zero-cross point (Zero
The time interval from 2) to the current zero-cross point (Zero4) is the extracted pitch data T. Therefore, in this embodiment, the time interval between zero cross points (ZOer1 → Zero3) that occurs immediately after the maximum value is detected and the time interval between zero cross points that occurs immediately after the minimum value is detected (Zero).
2 → Zero4) is obtained, the frequency change process can be performed twice in one cycle, and it can respond to the frequency change of the input signal. Pitch Settlement Processing The pitch calculation processing in steps B5 and C5 described above is performed based on the flowchart shown in FIG. The CPU 100 first sets the octave value OCT to 0 (step D
1) It is determined whether the extracted pitch data T is smaller than the reference pitch data T ₀ "4525" of FIG. 7 in the pitch data table 40 (step D2). If the extracted pitch data T is, for example, "9800", this data T "980
Since "0" is larger than the reference pitch data T ₀ "4525", the CPU
100 advances to step D3, and extracted pitch data T "9800"
Is set to 1/2 to be "4900", the octave value OCT is set to -1 to be "-1" (step D4), the process returns to step D2 again, and the half extracted pitch data T "4900" is used as a reference. Pitch data T ₀ Judge whether it is smaller than "4525". This time, since it is larger than the reference pitch data T ₀ , the processing of steps D3 and D4 is repeated again, and the extracted pitch data T is 1 /
Set it to 2 and set it to "2450".
Similarly, it is determined whether the extracted pitch data T "2450" is smaller than the reference pitch data T ₀ "4525" (step D2). Since it is smaller than the reference pitch data T ₀ this time, the process proceeds to step D5, and the extracted pitch data T "2450" is half of that.
It is determined whether the reference pitch data T _{0 is} larger than T ₀ “2262.5”. Since the extracted pitch data T "2450" is larger,
The CPU 100 proceeds to step D8, and the reference pitch data T ₀
The extracted pitch data T "2450" is subtracted from "4525" to obtain fractional data t "2075" less than the octave, and the order data m is set to "0" (step D9). It is determined whether or not the fractional data t "2075" is smaller than the difference pitch data dTm "129" corresponding to the order data m of "0" (step).
D10). Since the difference pitch data dTm is smaller, the CPU 100
Proceeding to step D11, subtracting the leading difference pitch data dTm “129” from the fractional data t “2075” to obtain “1946”,
The sequence data m is incremented by 1 to be "1" (step D1
2). Then, the CPU 100 repeats the processing of steps D11 and D12 until the fraction data t becomes smaller than the difference pitch data dTm, and the difference pitch data dTm is calculated from the fraction data t.
In order. Then, when the difference pitch data dTm is deducted to "73" and the order data m becomes "21", the fraction data t remains "17", and the next difference pitch data dTm (m = 21).
Since it is smaller than “70”, the CPU 100 proceeds to step D13, K = K ₀ + 12 × OCT + (m + t / dTm) /2=57.0+12×
Perform the operation of (-2) + (21 + 17/70) / 2 = 43.62,
Obtain new pitch data K. This pitch is a little higher than G ₁ ^# . Thus, A ₃ ~ stored in the pitch data table 40
With only the difference data dTm of the pitch for one octave of A ₄ ,
Pitch data for other octaves can be obtained. Further, if the extracted pitch data T is smaller than the reference pitch data T ₀ /2`2262.5 "of 1/2, CPU 100 is, 2 ⁿ times until extraction pitch data T in step D5~D7 is greater than" 2262.5 "( n = 1, 2, 3 ...), and thereafter, the above-mentioned steps D8 to D13 are performed to obtain the pitch data K. In summary, the CPU 100 multiplies the extracted pitch data T by 2 ⁿ times (n = ..., -2, -1, 0, step D1 to D7).
1, 2 ...) so that the pitch data stored in the pitch data table 40 falls within the range of the pitch data, the octave value OCT which is the value of n is obtained, and in steps D8 to D12, The note name is obtained from the correspondence between the fractional data less than the octave of the extracted pitch data T and the accumulated data of the difference pitch data dTm. In the above example, the difference pitch data in the right half of FIG.
Only dTm, order data m, reference pitch data K ₀ “57.0” and pitch data T ₀ “4525” are stored in the pitch data table 40. However, the pitch data T stored in the pitch data table 40 is It is also possible to use only the pitch data and pitch data T of the left half of FIG. When only the pitch data K and the pitch data T are used, steps D8 and D9 are omitted, and ²ⁿ times (n = ...
, -2, -1, 0, 1, 2, ...) It is determined whether the extracted pitch data T is smaller than the stored pitch data of each pitch in the pitch data table 40, and in step D11 the pitch data table The read address of 40 is incremented by 1, the step D12 remains unchanged, and the difference from the pitch data read from the pitch data table 40 immediately before the extracted pitch data T is t before the pitch calculation processing of step D13. The difference between the pitch data in the pitch data table 40 and the pitch data at the next address is set to dTm. The data stored in the pitch data table 40 includes the above-mentioned difference pitch data dTm, order data m, and reference pitch data K _0.
When only “57.0” and pitch data T ₀ “4525” are used, the number of digits of the difference pitch data dTm and the order data m is smaller than the number of digits of the pitch data K and the pitch data T, so the storage capacity is only that much. Although there is an effect that it can be small, even if the pitch data K and the pitch data T are also stored, the storage capacity will be smaller as compared with the conventional case where the pitch data is stored for every octave. There is no. Further, in the above-mentioned embodiment, the pitch is displayed as the serial number, but the octave, the scale name (chord),
The data may be expressed in semitones or less, and may be expressed in any other form. Further, in the above embodiment, the pitch data is stored in units of 50 cents (half a semitone), but may be stored in units of 100 cents (every semitone), or may be further segmented. It is possible to have such data for more than one octave. In addition, the method of pitch extraction is not limited to the above embodiment, and the present invention can be applied to various electronic musical instruments other than the electronic guitar. As described above in detail, the present invention compares the extracted pitch data output by the pitch extraction means with the pitch data stored in the storage means, and determines the input waveform signal based on the comparison result. Since the related note name is decided, it is not necessary to store the pitch data over a wide range of note for which the note name is decided, and the memory capacity can be reduced accordingly. The width of the data can be made narrower, and if the note name data corresponding to the note name is supplied to the sound source of the electronic musical instrument, it is possible to quickly produce a musical tone with a pitch that is faithful to the decided note name data. Play.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the overall circuit configuration of an embodiment of the present invention,
FIG. 2 is a diagram showing operation waveforms of respective parts in FIG. 1, FIG. 3 is a diagram showing a main flowchart of the CPU, and FIG. 4 is a diagram showing an interrupt processing flowchart at the time of detecting a zero cross point immediately after the maximum peak point. 5, FIG. 5 is a flowchart showing an interrupt process when a zero-cross point is detected immediately after the minimum peak point, FIG. 6 is a flowchart of a pitch calculation process subroutine, and FIG. 7 shows the contents stored in the pitch data table 40. It is a figure. 1 ... input terminal, 4 ... maximum peak detection circuit, 5 ... minimum peak detection circuit, 6 ... zero cross point detection circuit, 7 ...
… Counter, 8… Frequency ROM, 9… Sound source circuit, 10…
Sound system, 12 Latch, 14, 15 Flip-flop, 40 Pitch data table, 100 CP
U, 101 ... Work memory, P1 to P6 ... Pitch extraction circuit.

Claims (1)

(57) [Claims] Pitch extraction means for extracting the pitch of the input waveform signal and outputting pitch extraction data T, and a pitch range of at least one octave are divided into a plurality of pitch ranges, and each of these divided pitch ranges is sequentially represented by a pitch difference. Storage means for storing the differential pitch data dTm, reference pitch data T ₀ corresponding to the lowest pitch name in the one octave range, and pitch name data K ₀ corresponding to the reference pitch data T ₀ ; The pitch extraction data T and the reference pitch data T ₀ are compared in size, and the value of the pitch extraction data is multiplied by 2 ⁿ (n = ... -2, -1, 0, 1, 2) according to the comparison result. ......)
When searches the n as fall from the reference pitch data T ₀ to 1 in the range of 2 minutes of the reference pitch data T _0, based on the value of the retrieved n, and the pitch extraction data T An octave difference OCT from the reference pitch data T ₀ and an octave search means for determining a fractional data t less than an octave, and the pitch difference data dTm are sequentially read from the storage means, and the fractional data t less than the octave is Pitch-in-octave pitch searching means for dividing the octave pitch range stored in the storage means and searching for order data m indicating which of a plurality of pitch ranges arranged in order, the pitch name data K0, Octave difference OCT, fraction data t,
Pitch name data calculation means for determining pitch name data K based on pitch difference data dTm and order data m. An input waveform signal control device, characterized in that the pitch name data K is determined by using the following equation.