JPH07199938A - Acoustic signal generator - Google Patents

Abstract

PURPOSE:To eliminate foldover noise without increasing hardwares at the time of generating acoustic signals in the acoustic signal generator of the sound source of an electronic musical instrument or the like. CONSTITUTION:For one sounding instruction, to a waveform data memory, in a first sounding channel, the read of waveform data A from a waveform address specified by the sounding instruction with a step width specified by the sounding instruction is instructed. Simultaneously, in a second sounding channel, the read of the waveform data B from the waveform address obtained by adding an offset value which is 1/2 of the step width to the waveform address specified by the sounding instruction with the step width is instructed. The waveform data A and B are successively outputted to a D/A converter as the waveform data A+B in a cycle which is 1/2 of a sampling cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic signal generator such as a sound source of an electronic musical instrument, and more particularly to a technique for removing aliasing noise when an acoustic signal is generated.

[0002]

2. Description of the Related Art When converting an acoustic signal from digital data into an analog signal, the generation of aliasing noise poses a problem. When the acoustic signal has a signal component having a frequency higher than half the sampling frequency, this aliasing noise has a signal component whose frequency is equal to or lower than the highest frequency component of the acoustic signal in the conversion process. It is generated by being superimposed on the signal component.

In recent DACs (digital / analog converters), sampling frequencies of 2, 4,
There are some that can be converted at an oversampling frequency of 8 times. Then, conventionally, the acoustic waveform data generated in the acoustic signal generator is passed through a digital filter that operates at an oversampling frequency, and the sampling frequency of the acoustic waveform data is much higher than the highest frequency component of the waveform data. A technique is known in which aliasing noise is removed by raising the frequency to a certain oversampling frequency.

[0004]

However, such a conventional technique has a problem that a digital filter operating at an oversampling frequency is required, which increases the manufacturing cost of the acoustic signal generator. .

An object of the present invention is to eliminate aliasing noise without increasing hardware.

[0006]

The present invention is premised on an acoustic signal generator which reads out waveform data stored in a waveform data storage means (waveform memory 103) to generate acoustic waveform data.

First, in each of a plurality of tone generation channels obtained by time-dividing the sampling period, a waveform is generated at a designated step width from a designated waveform address on the waveform data storage means. It has a waveform data reading means (sound generation channel data generation unit) for reading data.

Next, in response to one sounding instruction, the step width of the step width specified by the sounding instruction is determined from the waveform address specified by the sounding instruction in each of the predetermined number of sounding channels to the waveform data reading means. A sound generation control means (CP) for instructing to read out waveform data with a step width specified by a sound generation instruction from a waveform address deviated by a predetermined number.
U101). More specifically, the sound generation control means, for example, for one sounding instruction, for the waveform data reading means, in the first sounding channel,
The reading of the waveform data is instructed from the waveform address specified by the sounding instruction with the step width specified by the sounding instruction, and the waveform address specified by the sounding instruction is specified by the sounding instruction in the second sounding channel. The waveform data is instructed to be read with the step width specified by the tone generation instruction from the waveform address obtained by adding the offset value of 1/2 of the step width.

Then, the acoustic waveform data generated by the waveform data reading means on the basis of the waveform data read out in each of the predetermined number of sound generation channels is sequentially D / S at a period of a predetermined fraction of the sampling period. It has acoustic waveform data output means (sound generation channel data output section) for outputting to an A converter or the like. More specifically, the acoustic waveform data output means reads the acoustic waveform data generated based on the waveform data read in the first sounding channel described above and the second sounding channel described above. The acoustic waveform data generated based on the generated waveform data is sequentially D / A at a cycle of 1/2 the sampling cycle.
Output to converter etc.

In the above-mentioned configuration of the invention, the sound generation control means is arranged such that the sounding instruction has a predetermined attribute, for example, a note-on instruction of a musical tone in a predetermined musical range, or a musical tone having a predetermined tone color in the predetermined musical range. In the case of the note-on instruction of the above, the above-described operation is performed, and in other cases, the normal sounding processing using only one sounding channel is performed, for example. The invention can also be configured.

[0011]

The oversampling process can be realized by simply controlling a plurality of tone generation channels at the same time without using a special digital filter for oversampling, and aliasing noise can be removed.

Further, by simultaneously controlling a plurality of sound generation channels only when necessary according to the attribute of the sound generation instruction, it is possible to effectively use the sound generation channels.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, FIG. 1 is an overall configuration diagram of an embodiment in which the present invention is applied to an electronic keyboard instrument.

The note data for designating the pitch and the velocity data for designating the key pressing strength generated by the key pressing operation on the keyboard 105 are sent to the CPU via the bus 106.
After being detected by 101, converted to step value data and envelope value data when waveform data is read from the waveform memory 103, and then to the sound source 102 via the bus 106, corresponding to a free sounding channel to be processed by the sound source 102. Is set as the data to be set.

The sound source 102 stores the waveform address integer part W in the waveform memory 103 by time division processing for each sounding channel.
Waveform data WDT that supplies AD and is output from it
Is taken in as sounding channel data. Then, the tone generation channel data of each tone generation channel is added in synchronization with the sampling frequency, and the addition result is the D / A converter 1.
It is output to 04. In this case, as a feature related to the present invention, each waveform data in the waveform memory 103 is oversampled by using two sounding channels, and the resulting sounding channel data of the two sounding channels are:
It is output to the D / A converter 104 at an oversampling rate that is twice the sampling frequency.

The D / A converter 104 converts the output waveform data into an analog musical tone waveform signal at an oversampling rate that is twice the sampling frequency. The analog musical tone waveform signal is amplified by the amplifier 107 and then the speaker. 1
It is emitted as a musical sound from 08.

Next, the sound source 102 of FIG. 1 has eight sound generation channel data generators each having the structure shown in FIG. 2 and eight sound generators that latch the sound generation channel data generated by each sound generation channel data generator. The sound channel data output section shown in FIG. 3 including the channel data latch 301.

The eight tone generation channel data generators are shown in FIG.
As shown in (a), the waveform address is generated and the integer part WAD is stored in the waveform memory 103 of FIG. 3 to generate sound channel data from the waveform data WDT obtained as a result,
The sounding channel data latch 301 shown in FIG. The sound generation channel data latched in each sound generation channel data latch 301 is shown in FIG. 3 at the change timing of the current sampling period and the next sampling period.
Adder 303 according to the settings of eight switches 302
Or 304, the addition result of the adder 303 is the first output waveform data A to the first output latch 305, and the addition result of the adder 304 is the second output waveform data B.
Are respectively latched by the second output latch 306. First output waveform data A and second output waveform data B
Are sequentially output to the D / A converter 104 of FIG. 1 at a cycle of 1/2 of the sampling cycle T, as shown in FIG. 4 (b).

Next, the detailed operation of the tone generation channel data generating section of FIG. 2 will be described. From the CPU 101 of FIG. 1, the start address of the waveform data stored in the waveform memory 103 and from which the reading is to be started is set in the address register 204 from the bus 106 via the switch 203. Value register 201
In addition, step value data indicating the step width when the waveform data is read from the waveform memory 103, and envelope value data for determining the strength of the sounding channel data output from the bus 106 to the envelope value register 209. Set. Here, the step value data corresponds to the note data, and the envelope value data corresponds to the velocity data.

The waveform address in the address register 204 is passed through the adder 202 and the switch 203, as shown in FIG.
At each timing corresponding to any number in each sampling period of (a), with the step width indicated by the step value data set in the step value register 201 from the head address set at the start of sounding, It is sequentially incremented. In this case, since the step value data can specify a real value, the waveform address also becomes a real value. Then, the integer part WAD of this waveform address is output to the waveform memory 103 in FIG.

In the portion consisting of the data register 205, the subtractor 206, the multiplier 207, and the adder 208,
Waveform data WDT (n +) corresponding to the current sampling period T (n + 1) read from the waveform memory 103
1) and the waveform data WD corresponding to the previous sampling period T (n) held in the data register 205.
T (n) and the fractional part of the waveform address output from the address register 204. From WAD, the waveform data corresponding to the real number address data obtained in the address register 204 is calculated by the linear interpolation calculation. The principle of linear interpolation calculation is shown in FIG. First, the subtractor 206
Waveform data WDT (n +) corresponding to the current sampling period T (n + 1) read from the waveform memory 103
The waveform data WD corresponding to the previous sampling period T (n) held in the data register 205 in 1)
The difference with respect to T (n) is calculated. Next, the multiplier 207
However, the difference value is added to the waveform address fractional part. The increment value from the waveform data WDT (n) corresponding to the immediately preceding sampling cycle T (n) is calculated by multiplying the ratio corresponding to WAD. Then, the adder 208 uses this increment value as the waveform data W corresponding to the immediately preceding sampling period T (n) output from the data register 205.
By adding to DT (n), the address register 2
The waveform data corresponding to the real number address data obtained in 04 is calculated.

The multiplier 210 calculates the tone generation channel data WO _CH by multiplying the above waveform data by the envelope value data. Here, the CPU 101 of FIG.
Determines the start of sounding one musical sound, sets the same step value data and envelope value data in the two sounding channel data generators in the sound source 102. Further, the CPU 101 sets the start address of the waveform data stored in the waveform memory 103 and from which the reading is to be started in the address register 204 in the one tone generation channel data generation unit, and the other tone generation channel data generation unit in the other tone generation channel data generation unit. In the address register 204, an address obtained by adding an offset value of 1/2 of the step value data to the start address is set. As a result, the two sound generation channel data generation units generate, from the same waveform data on the waveform memory 103, as shown as waveform data A and waveform data B in FIG. Therefore, the tone generation channel data which is out of phase with each other is generated.

The two tone generation channel data thus generated are held in any two of the eight tone generation channel data latches 301 shown in FIG. Then, one tone generation channel data is held as the first output waveform data A in the first output latch 305 via the switch 302 to which the tone generation channel data latch 301 holding the same is connected and the adder 303, and the other one. The pronunciation channel data is stored in the pronunciation channel data latch 30 in which it is held.
After being held as the second output waveform data B in the second output latch 306 via the switch 302 and the adder 304 to which 1 is connected, as shown in FIG. Of the D / A converter 104 of FIG.
Are sequentially output to. As a result, the first output waveform data A and the second output waveform data B are combined and the switch 3 of FIG.
As shown in FIG. 6, the output waveform data A + B output from 07 is data oversampled at a speed twice the sampling frequency.

In the above operation, when the CPU 101 determines two empty tone generation channels at the start of each tone, the CPU 101 of FIG. 3 corresponding to the tone generation channel for setting only the leading address of the waveform data in the address register 204 of FIG. Switch 302 is set so that its output is output to the adder 303 side, and the address register 2 of FIG.
04 (waveform data start address + step value data 1
The output of the switch 302 of FIG. 3 corresponding to the tone generation channel for which the (/ 2 offset value) is set is an adder 304.
Set to output to the side.

As explained above, the sound source 102 of FIG.
In addition, the oversampling function can be realized only by adding the simple circuit shown in FIG. Here, the above-described oversampling process may not be applied to all the musical tones for which sound generation is started, but may be applied only to the musical tones requiring the oversampling process in order to effectively use the sound generation channel. Conceivable. Specifically, when the pitch of the waveform data designated to be read in the waveform memory 103 is high and there are many signal components in the high frequency region, or the waveform data designated to be read in the waveform memory 103 contains many overtones. When the signal component reaches the frequency domain, it is effective to perform the above oversampling process.

Based on such criteria, the CPU 1 of FIG.
7 and 8 show operation flowcharts of the first embodiment of the control operation for sounding instruction, which is executed by 01. First,
In step 701, the contents of various registers in the CPU 101 and the sound source 102 are initialized.

Next, in step 702, after the value of the register n in the CPU 101 is initialized to 0, the value of the register n is incremented by +1 in step 714, and the value of the register n is incremented in step 715 of FIG. Is Figure 1
Until it is determined that the number of keys of the keyboard 105 has been exceeded, the following control processing of steps 703 to 711 is executed.

First, in step 703, the state of the key at the position corresponding to the value of the register n is determined. Step 70
If it is determined in 3 that the state of the key at the position corresponding to the value of the register n does not change, no processing is performed, and in step 714, the value of the next register n is incremented to determine the next key position. The control process for is executed.

If it is determined in step 703 that the key at the position corresponding to the value of the register n has been turned on (ON), steps 704 to 711 are executed. That is,
First, in step 704, the value of the register n indicating the position of the key to be processed is substituted into the register TNR in the CPU 101, and then in step 705, this register TNR
Whether or not the value of is greater than or equal to the value of the register SPLIT which stores the key positions for dividing the key range on the keyboard 105 in advance,
That is, it is determined whether or not the position of the note-on key is within the predetermined upper key range.

If it is determined in step 705 that the value of the register TNR is greater than or equal to the value of the register SPLIT, then in step 706, the sound source 102 detects an empty tone generation channel that is not currently sounded.

Further, in step 707, step 706
As a result of the detection processing in step 1, it is determined whether or not there are two free tone generation channels. When the CPU 101 determines in step 707 that there are two free tone generation channels, in step 708, the register TN indicating the position of the key, that is, the pitch is displayed.
Step value data corresponding to the value of R, and step 7 described later.
The start address of the waveform data corresponding to the tone color number set in the register TCR in the CPU 101 by the process of 18, and especially the envelope value data corresponding to the velocity data of the note-on key held in the register not shown. Are transferred to the two sound generation channel data generation units in the sound source 102 corresponding to the two empty sound generation channels. In this case, as described above, the CPU 101 sets only the start address of the waveform data stored in the waveform memory 103 and from which reading is to be started, in the address register 204 in one of the tone generation channel data generation units, In the address register 204 in the other tone generation channel data generation unit, an address obtained by adding an offset value of 1/2 of the step value data to the above-mentioned start address is set. Further, the CPU 101, as described above, uses the sound source 102 corresponding to the above two sounding channels.
It also controls the switch 302 shown in FIG.

In this way, when a note on a key in a predetermined upper key range is made on a note, a tone generation process based on oversampling using two tone generation channels is performed.

After the processing of step 708 is executed,
In step 714, the value of the next register n is incremented and the control process for the next key position is executed. On the other hand, when a key in a key range equal to or lower than the predetermined upper key range is note-on and the determination in step 705 is NO and the detection processing of the empty sound generation channel is executed in step 709, or when the key in the predetermined upper key range is note Even if it is turned on, if it is determined in step 707 that there are no empty tone generation channels, it is further determined in step 710 whether or not there is one empty tone generation channel.

If the CPU 101 determines in step 710 that there is one vacant tone generation channel, it executes step 7
In step 11, step value data corresponding to the value of the register TNR indicating the position of the key, that is, the pitch, and step 718 described later.
By the processing of the above step, the start address of the waveform data corresponding to the tone color number set in the register TCR in the CPU 101, and the envelope value data corresponding to the velocity data of the note-on key held in the register (not shown) are displayed. , To the sound generation channel data generation unit in the sound source 102 corresponding to the above-mentioned empty sound generation channel.

In this way, even if a key in the key range equal to or lower than the predetermined upper key range is note-on, or even if a key in the predetermined upper key range is note-on, the empty tone generation channel is 1
If there is only one, normal sounding processing other than oversampling processing is performed. It should be noted that when a key in a predetermined upper range is note-on and there is only one free sounding channel, the oversampling process cannot be performed. Since a plurality of musical tones are being pronounced, folding noise is masked by those musical tones and becomes inconspicuous.

After the processing of step 711 is executed,
In step 714, the value of the next register n is incremented and the control process for the next key position is executed. If it is determined in step 710 that there are no free sound generation channels, sound generation processing is not performed and step 714
Then, the value of the next register n is incremented and the control process for the next key position is executed.

Next, when it is determined in step 703 described above that the key at the position corresponding to the value of register n has been turned off (OFF), the note number corresponding to the value of register n is determined in step 712. After the assigned sounding channel is detected, the mute processing is executed for the sounding channel in step 713.

After the processing of step 713 is executed,
In step 714, the value of the next register n is incremented and the control process for the next key position is executed. By the above steps 702 to 715 of FIG. 8,
After the detection of the state change and the tone generation control processing for all the keys are executed, the setting state of the tone color switch (not shown) is operated in step 716 of FIG.
If it is determined that there is a change in the setting state of the switch, a new tone color number is set in the register TCR in step 718.

Thereafter, the control is returned to the processing of step 702, and the above processing is repeated. Next, the CPU 1 of FIG.
9 and 10 show operation flowcharts of the second embodiment of the control operation for sounding instruction executed by 01.

First, in step 901, the CPU 101
Also, the contents of various registers in the sound source 102 are initialized. Next, in step 902, the CPU 101
After initializing the value of the register n in the register 0 to 0, the value of the register n exceeds the number of keys of the keyboard 105 of FIG. 1 in step 923 of FIG. 10 while the value of the register n is incremented by +1 in step 922. Until it is determined that it is determined, the control processing of the following step 903 to step 919 of FIG. 10 is executed.

First, in step 903, the state of the key at the position corresponding to the value of the register n is determined. Step 90
If it is determined in 3 that the state of the key at the position corresponding to the value of the register n does not change, no processing is performed, and in step 922, the value of the next register n is incremented to determine the next key position. The control process for is executed.

If it is determined in step 903 that the key at the position corresponding to the value of the register n has been turned on (ON), steps 904 to 912 are executed. That is,
First, in step 904, the value of the register n indicating the position of the key to be processed is substituted into the register TNR in the CPU 101, and then in step 905, this register TNR
Whether or not the value of is greater than or equal to the value of the register SPLIT which stores the key positions for dividing the key range on the keyboard 105 in advance,
That is, it is determined whether or not the position of the note-on key is within the predetermined upper key range.

If it is determined in step 905 that the value of the register TNR is greater than or equal to the value of the register SPLIT, then in step 906 the register UTCR in the CPU 101 is set by the processing of step 926, which will be described later. It is determined whether the tone color number of the key range is the number of a specific tone color (for example, tone color having many overtone components) to be oversampled.

If the determination in step 906 is YES, then in step 907, a vacant tone generation channel in which tone generation processing is not currently performed in the sound source 102 is detected. Further, in step 908, it is determined whether or not there are two free tone generation channels as a result of the detection processing in step 907.

If the CPU 101 determines in step 908 that there are two free tone generation channels, the CPU 101 proceeds to step 90.
In step 9, it corresponds to the step value data corresponding to the value of the register TNR indicating the position of the key, that is, the pitch, and the tone color number of the upper key range set in the register UTCR in the CPU 101 by the processing of step 926 described later. The start address of the waveform data and the envelope value data corresponding to the velocity data of the note-on key held in a register (not shown) are used as two tone generation channels in the tone generator 102 corresponding to two empty tone generation channels. Transfer to the data generator. In this case, as described above, the CPU 101 sets only the start address of the waveform data stored in the waveform memory 103 at which the reading is to be started in the address register 204 in one of the tone generation channel data generation units, and the other one. An address obtained by adding a 1/2 offset value of the step value data to the above-mentioned head address is set in the address register 204 in the sound generation channel data generator. Further, the CPU 101 uses the sound source 10 corresponding to the above-mentioned two sound generation channels as described above.
It also controls the switch 302 shown in FIG.

In this way, when a key in a predetermined upper key range is note-on and a predetermined tone color is assigned to the upper key range, it is based on the oversampling process using two sound generation channels. Musical tone generation processing is performed.

After the processing of step 909 is executed,
At step 922, the value of the next register n is incremented and the control processing for the next key position is executed. On the other hand, the tone color number of the upper key range set in the register UTCR is not the number of the specific tone color for which the oversampling process is to be performed, but the determination in step 906 is NO, and subsequently, in step 910, the detection process of the empty tone generation channel is executed. Or if it is a specific tone, step 90
If it is determined in step 8 that there are no empty tone generation channels, it is further determined in step 911 whether there is one empty tone generation channel.

If the CPU 101 determines in step 911 that there is one free tone generation channel, the CPU 101 proceeds to step 9
12, step value data corresponding to the value of the register TNR indicating the position of the key, that is, the pitch, and step 926 described later.
By the processing of 1., it corresponds to the start address of the waveform data corresponding to the tone color number of the upper key range set in the register UTCR in the CPU 101, and the velocity data of the note-on key held in the register (not shown). The envelope value data is transferred to the sound generation channel data generation unit in the sound source 102 corresponding to the above-mentioned empty sound generation channel.

In this way, when a key in a predetermined upper key range to which a tone color other than a specific tone color is assigned is note-on, or a key in a predetermined upper key range to which a specific tone color is assigned is Even if the note-on is performed, if there is only one free sounding channel, the normal sounding processing other than the oversampling processing is performed.

After the processing of step 912 is executed,
At step 922, the value of the next register n is incremented and the control processing for the next key position is executed. If it is determined in step 911 that there are no free sound generation channels, sound generation processing is not performed and step 922 is performed.
Then, the value of the next register n is incremented and the control process for the next key position is executed.

On the other hand, if the keys in the key range equal to or lower than the predetermined upper key range are note-on and the determination in step 905 is NO, further in step 913 of FIG. Register LTCR
It is determined whether or not the tone color number of the lower key range set to is the number of the specific tone color to be oversampled.

If the determination in step 913 is YES, then in step 914, an empty tone generation channel for which tone generation processing is not currently performed in the sound source 102 is detected. Further, in step 915, it is determined whether or not there are two free tone generation channels as a result of the detection processing in step 914.

If the CPU 101 determines in step 915 that there are two free tone generation channels, the CPU 101 proceeds to step 91.
In step 6, it corresponds to the step value data corresponding to the value of the register TNR indicating the position of the key, that is, the pitch, and the tone color number of the lower key range set in the register LTCR in the CPU 101 by the processing of step 929 described later. The start address of the waveform data and the envelope value data corresponding to the velocity data of the note-on key held in a register (not shown) are used as two tone generation channels in the tone generator 102 corresponding to two empty tone generation channels. Transfer to the data generator. In this case, as described above, the CPU 101 sets only the start address of the waveform data stored in the waveform memory 103 at which the reading is to be started in the address register 204 in one of the tone generation channel data generation units, and the other one. An address obtained by adding a 1/2 offset value of the step value data to the above-mentioned head address is set in the address register 204 in the sound generation channel data generator. Further, the CPU 101 uses the sound source 10 corresponding to the above-mentioned two sound generation channels as described above.
It also controls the switch 302 shown in FIG.

In this way, when a key in a predetermined lower key range is note-on and a predetermined tone color is assigned to the lower key range, it is based on an oversampling process using two sound generation channels. Musical tone generation processing is performed.

After the processing of step 916 is executed,
At step 922, the value of the next register n is incremented and the control processing for the next key position is executed. On the other hand, the tone color number in the lower key range set in the register LTCR is not the number of the specific tone color to be oversampled, but the determination in step 913 is NO, and in step 917, the detection process of the empty tone generation channel is executed. If it does, or if it is a specific timbre, step 91
If it is determined in step 5 that there are no empty tone generation channels, it is further determined in step 918 whether there is one empty tone generation channel.

If the CPU 101 determines in step 918 that there is one vacant tone generation channel, the CPU 101 proceeds to step 9
In 19, the step value data corresponding to the value of the register TNR indicating the position of the key, that is, the pitch, and step 929 to be described later.
By the processing of 1., it corresponds to the start address of the waveform data corresponding to the tone color number of the lower key range set in the register LTCR in the CPU 101, and the velocity data of the note-on key held in the register (not shown). The envelope value data is transferred to the sound generation channel data generation unit in the sound source 102 corresponding to the above-mentioned empty sound generation channel.

In this way, when a key in a predetermined lower key range to which a tone color other than a specific tone color is assigned is note-on, or a key in a predetermined lower key range to which a specific tone color is assigned is Even if the note-on is performed, if there is only one free sounding channel, the normal sounding processing other than the oversampling processing is performed.

After the processing of step 919 is executed,
At step 922, the value of the next register n is incremented and the control processing for the next key position is executed. If it is determined in step 918 that there are no free sound generation channels, sound generation processing is not performed and step 922 is performed.
Then, the value of the next register n is incremented and the control process for the next key position is executed.

Next, in step 903 of FIG. 9 described above,
The key at the position corresponding to the value of register n is the note-off (OF
F), it is determined in step 920 that the tone generation channel to which the note number corresponding to the value of the register n is assigned is detected, and then in step 921,
The mute processing is executed for the sound generation channel.

After the processing of step 921 is executed,
At step 922, the value of the next register n is incremented and the control processing for the next key position is executed. After the state change detection and sound generation control processing for all the keys are executed by the above steps 902 to 1023 of FIG. 9, at step 924 of FIG. If it is determined in step 925 that the switch setting state has changed, then in step 926 the register U
A new tone color number is set in the TCR.

Subsequently, in step 927, the setting state of the lower key tone color switch (not shown) is operated, and if it is determined in step 928 that the setting state of the switch has changed, then in step 929, the register LTCR is registered. A new tone color number is set to.

Thereafter, the control is returned to the processing of step 902 in FIG. 9, and the above processing is repeated.

[0063]

According to the present invention, oversampling processing can be realized by simply controlling a plurality of sound generation channels at the same time without using a special digital filter for oversampling, and aliasing noise is removed. It becomes possible. Therefore, it is possible to suppress an increase in the cost of the acoustic signal generator.

Further, depending on the attribute of the sounding instruction, the sounding channels can be effectively used by simultaneously controlling the plurality of sounding channels only when necessary.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a sound generation channel data generation unit in a sound source.

FIG. 3 is a configuration diagram of a sound generation channel data output unit in a sound source.

FIG. 4 is an operation timing chart of a sound source.

FIG. 5 is an explanatory diagram of linear interpolation calculation of waveform data.

FIG. 6 is an explanatory diagram of a sound source oversampling operation.

FIG. 7 is an operation flowchart (No. 1) of the first embodiment of the control operation of the CPU.

FIG. 8 is an operation flowchart (No. 2) of the first embodiment of the control operation of the CPU.

FIG. 9 is an operation flowchart (part 1) of the second embodiment of the control operation of the CPU.

FIG. 10 is an operation flowchart (part 2) of the second embodiment of the control operation of the CPU.

[Explanation of symbols]

 101 CPU 102 Sound source 103 Waveform memory 104 D / A converter 105 Keyboard 106 Bus 107 Amplifier 108 Speaker 201 Step value register 202, 208 Adder 203 Switch 204 Address register 205 Data register 206 Subtractor 207, 210 Multiplier 209 Envelope value Register 301 Sound channel data latch 302, 307 Switch 303, 304 Adder 305 First output latch 306 Second output latch

Claims (3)

[Claims] 1. An acoustic signal generator for reading out waveform data stored in a waveform data storage unit to generate acoustic waveform data, wherein a plurality of sound generation channels obtained by time-dividing the sampling period for each sampling period. In each of the above, waveform data reading means for reading the waveform data at a designated step width from a designated waveform address on the waveform data storage means; and for one sounding instruction, for the waveform data reading means. In each of the predetermined number of the sounding channels, the sounding instruction specifies a waveform address that is deviated from the waveform address specified by the sounding instruction by a predetermined number of steps of the step width specified by the sounding instruction. Sound generation control means for instructing the reading of the waveform data with a step width, and the waveform data reading means. Acoustic waveform data output means for sequentially outputting acoustic waveform data generated based on the waveform data read in each of the predetermined number of sound generation channels in a cycle of a predetermined fraction of the sampling cycle, An acoustic signal generator having: 2. An acoustic signal generator for reading out waveform data stored in a waveform data storage means to generate acoustic waveform data, wherein a plurality of sound generation channels obtained by time-dividing the sampling period for each sampling period. In each of the above, waveform data reading means for reading the waveform data at a designated step width from a designated waveform address on the waveform data storage means; and for one sounding instruction, for the waveform data reading means. In the first sounding channel, the reading of the waveform data is instructed from the waveform address specified by the sounding instruction with the step width specified by the sounding instruction, and in the second sounding channel, The waveform address specified by the sounding instruction has an offset of 1/2 of the step width specified by the sounding instruction. Tone generation control means for instructing the reading of the waveform data with a step width specified by the tone generation instruction from the waveform address obtained by adding the tone value, and the waveform data reading means for reading in the first tone generation channel. The acoustic waveform data generated based on the output waveform data and the acoustic waveform data generated based on the waveform data read in the second sound generation channel are set to half of the sampling period. An acoustic signal generation device, comprising: an acoustic waveform data output unit that sequentially outputs in a cycle. 3. The acoustic signal generation device according to claim 1, wherein the sound generation control means operates when the sound generation instruction has a predetermined attribute.