JPS59113495A - Envelope controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an envelope control device suitable for performing multiplication in image processing, such as in an electronic musical instrument in which a sound source waveform and an envelope waveform are multiplied.

Conventional configuration and its problems Conventionally, in the field of electronic musical instruments, when creating a musical sound waveform with an envelope by multiplying a sound source waveform and an envelope waveform, a digital multiplier with 12 bits ×
If a bit width of 12 pits or more is not used, there is a problem in that when the envelope is attenuated, noise is generated due to quantization errors and is audible. The DA converter still requires a 14-bit to 16-bit resolution, and the envelope waveform also requires a resolution of 14 to 16 bits. Japanese Patent Laid-Open Nos. 5.4-1609 and 1981-181593 are known as methods that display binary floating point numbers instead of using 16-bit linear codes as envelope waveforms. However, for multiplication with the sound source waveform, analog multipliers or linear parallel multipliers such as 16 bits x 16 pits have conventionally been used.

OBJECTS OF THE INVENTION The present invention provides an envelope control device that can perform multiplication of a waveform and an envelope using a multiplier that is smaller than ever before.

Structure of the Invention The present invention generates envelope data E divided into two parts, a lower code P and an upper code Qi, and multiplies the lower code P or a modified version thereof by waveform data Wi. , the multiplication result is shifted according to the upper code Q, and the multiplier is set to W,
It is characterized in that instead of iO, it is made smaller to W, XPi, or even slightly larger scale.

Description of examples FIG. 1 is a block diagram showing the principle of the present invention.

Reference numeral 1 denotes a waveform generator that generates waveform data Wi of a musical sound source, which samples one waveform of a musical sound and repeatedly generates quantized data. 3 is a waveform data register. 2 is an envelope generator that generates envelope data Ei.

The envelope data E has a structure that can be separated into lower P and upper Qi. 4 is a register for the lower code P, and register 5 is a register for the upper code Q. The waveform data W and lower code Pi are applied to a multiplier 6.

At this time, further above the most significant bit of the lower code P,
Therefore, when Pi is 8 bits, the multiplier 6 is given 9 bits of data.

The other input of the multiplier 6 receives waveform data W. This data will be composed of 10 bits. For the output of the multiplier 6, the most significant bits out of 10+9=19 bits are used.

This product code WP1 is input to the shifter 8. The shifter shifts the bits of the input code and outputs it, and specifies how many bits to shift to the upper or lower order of the upper code Qi of the envelope data.

Here, the envelope Cheetaka ((J3'J2(11q□p7P6P51)4P3p2
PI P□) (1)7~p□J
represents the mantissa part, and cr3 to qo) represent the exponent part.

The size of Ei is It is expressed as a binary floating value, such as .

By adding '1゛ to the upper part of P, Ei becomes essentially becomes. (The inside of j is expressed as Pi.

On the other hand, if W is 10 bits, then However, this means that negative numbers are represented as two's complement and WPi
The term is calculated by a 10-bit x 9-bit multiplier 6.

The term 2j Tomoe, , q52j corresponds to performing 16 shifts according to the upper code Qi, where Qi = (oooo) there is no shift, Qi: (Ooool), there is a 1-bit shift to the upper order, Q,
= (oolo), 2 bit shift to the upper position), Q, = (1
111), the data is shifted upward by 16 bits. Therefore, if WPi is 12 bits, the output of shifter 8 will have a width of 12 + 15 = 27 bits, but if only the upper 16 bits are taken out,
It will be input to the DA converter 9. In this way, since WPi is 12 bits, the S/N against quantization noise is approximately 72 dB, and the dynamic range is 5 edB, corresponding to 16 bits, making it possible to obtain sufficiently high quality sound. I can do it.

FIG. 2 is another example illustrating the principles of the invention.

The differences from Figure 1 will be explained. The digital shifter 8 is omitted, and instead, an attenuator 1o corresponding to an analog shifter is provided at the output of the DA converter 9, and the attenuation AT is switched by the upper code Q1. The attenuation degree AT is expressed by . K is a constant. If you do this, D
Since the A converter 9 may have 12 bit precision, this is more advantageous than the example shown in FIG.

A in FIG. 3 is an example of P and Q. It shows the attenuation process of the envelope, the so-called release. Pi is 2
Pi changes from 611 to 256 by changing from 66 to 0''!. FIG. 4A shows the format of QiIP, fPi.

FIG. 6 is another example illustrating the principle of the invention.

The waveform data Wi and the lower code P are applied to the multiplier 6, and the product output is shifted by the shifter 8 according to the upper code Q. Waveform data W1 is also shifted by shifter 18. The outputs of shifters 8 and 18 are applied to a subtracter 2o, where their difference is taken. The output of the subtracter 2o is input to the DA converter.

In FIG. 6, the order of the subtracter 2o in the shifters 8 and 9 of the example in FIG. 5 is reversed to reduce the number of shifters to one, and the bit width to be handled by the subtracter 20 is reduced.

In the examples shown in FIGS. 5 and 6, it is assumed that the envelope data Ei is generated so that it becomes an increasing function in its attenuation process. Examples of values are shown in FIG. 3B. Figure 4B
is the format of envelope data.

FIG. 7 is an example of an analog shifter. In FIG. 7, the resistors are a well-known R-2R type ladder network. A switch is provided in the 2R resistor example to select the flow of current into the intermediate input of the operational amplifier 31 and the input power.

R, is a feedback resistor that determines the gain, and 30, through which current flows into the human power, is a decoder, and the upper code Qi
Accordingly, one of the 16 switches is selected and switched to the - input terminal. No attenuation for switch So, -edB for switch S, -12 dB for switch S2.

becomes. At switch S, it becomes -6X i dB.

In S16, where the attenuation is the largest, it is Qi-(1111). In this case, the switch may be fixed to the middle input side so that the input is cut off.

In FIG. 7, 16 levels are generated, which is more than enough for normal sounds. Q may be 3 bits. Q
Even if i is 4 bits, without using all 16 ways,
Only about 10 to 12 bits may be used.

In the case of the code shown in FIG. 3B, the correspondence between the decoder and the switch shown in FIG. 7 may be reversed.

In the examples shown in Figures 1 and 2, Pi and Qi decrease and go to ℃, Qi = (0000), and furthermore, P becomes (
Q
1 = (1111) and BORROW occurs, but at this time, Qi = (1111) and BoRR
oW is detected, 6,=(oooo) is supplied to the shifter in place of Qi, and the upper additional bit of R1 is
If it is switched from 1" to 'o°", then as Pi, when Qi = (oool) ~ (1110), p, = 511 ~ 266 can be taken, and when Q, = (oooo), △ Pi : Values from 511 to 0 can be taken.

In each of the above examples, the case where the product of waveform data and envelope data is directly DA converted is explained. However, based on this principle, the present invention calculates the difference value between the two subsequent products and shifts the difference value. It was designed to do so.

FIG. 8 shows an embodiment of the present invention in which a difference value regarding i between W and XEi is output.

P, which is obtained by adding 1゛ to waveform data W0 and lower order data P,
is added to the multiplier 60, resulting in the product WP.

get. Since the product WP is applied to the latch 4o, the previous product wp1 is held at time i.

The upper code Qi of the envelope data E is the latch 4.
2. The signal is supplied to a comparator 43... and an attenuator 1o which is an analog shifter. The previous upper code Q□-1 is held in the latch 42 and is supplied to the comparator 43. Comparator 43 compares Qi and Qi-1 and outputs an output based on the following conditions.

Oi>Oi, :a Qi-Q, -1:b Qi<Qi-1" The output wp lt of the latch 40 is supplied to the shifter 41. The shifter 41 shifts wp=, up or down by 1 bit. It can be configured by a combination of an AND gate and an OR gate.The signal that enters input terminal A is shifted one bit lower.The signal that enters input terminal B is output as is.The signal that enters input terminal C The input signal wp is shifted upward by one bit. Therefore, the input wp, , is converted as follows.

a: Select A: +WPi-1 Select b2B: WPi-1 C: Select C: 2WP, -.

The output of the shifter 41 and the product are supplied to a subtracter 61 to calculate the difference. The differential output is as follows.

When Q, > Q, , ΔWP, ==-)WP, -1-wp.

When Qi''Qi-1, ΔWP, =:WP, -WP 1 l+1 Q, <Q, -1, ΔWP, =2WP l-1-wpi The output ΔWP of the i subtracter 61 is the same as the DA converter 9. It is applied to an integrator consisting of a capacitor C and an operational amplifier 11 via an attenuator 10. Since the difference value Δwp corresponds to the differential value of WPi, the output of the integrator has a waveform of the product of Wi and E. Become.

The comparator 43 and shifter 41 are connected to the upper code Qi and Qi-
1 is different. That is, this is to correct the difference between P and ΔP, -1 when the range of the index display section of the envelope de Δ is different, so that a correct difference value ΔWPi can be obtained.

Since ΔWP is the difference between WPi and WPi-1, WP
Even if i is 12 bits, the word width of ΔWP is usually small. Therefore, in this embodiment in which the difference is divided, the word width of the DA converter 9 can be made 12 bits or less.

In the embodiment shown in FIG. 8, the comparator 43 and the shifter 41. The subtracter 61 constitutes a differentiator.

FIG. 9 shows another example of the DA converter 9 used in FIG. The difference value ΔWP is the shifter 70. DA converter finished 1
．． It is outputted via an analog shifter 72 and applied to the attenuator 1o in FIG. Shifter 70 and shifter 72 are supplied with the upper 3 bits of 7-bit data of ΔWPi to control the shift operation. ΔW as in Figure 10
When the upper 3 bits of P are 1+o++, the lower 4 bits are directly applied to the DA converter 71 and are sent to the shifter 72.
The gain is a layer.

That is, it becomes -12dE. As shown in FIG. 10B, when the upper 3 bits are "Oo1°", the middle 4 bits are output to the shift operation of the shifter 7o, and these are output to the DA.
In addition to the converter 71, the shifter 72 has a gain dedicated to -
It becomes edB. As shown in Figure 10 C), the top two of ΔWP,
When the bit is "o i", the upper 4 bits excluding the MSB (most significant bit) are applied to the DA converter 71, and the shifter 72 has an attenuation degree of 0 dB.

The above explanation applies when ΔWP is positive. ΔWP.

FIG. 11 shows a case in which the two's complement representation is performed when is negative. In FIG. 11, when the upper 3 bits are "111'", the lower 4 bits shown in FIG. 11 are directly applied to the DA converter 71. Shifter 72 provides -12 dB.

When the upper 3 bits are “i io”, the 11th
Shifter 70 outputs the middle 4 bits in FIG. The shifter 72 becomes -6 dB. The top 2 bits are "10 '"
At this time, the 4 bits shown in FIG. 11F are output from the shifter 70. The shifter 72 becomes odB. Of the 7 bits of ΔWPi, the MSB is inverted and applied to the MSB input of the DA converter 71. In this way, this complement representation is converted to an offset binary representation.

The waveform generator 1 outputs a digital sound source waveform, and may be one that sequentially reads out data written in a storage device. As the envelope generator 2, an up/down counter or the like is used.

It goes without saying that even when using increasing function type envelope data E as shown in FIGS. 5 and 6, it is possible to adopt a configuration that calculates the difference value as shown in FIG. 8.

Effects of the Invention As is clear from the above explanation, the present invention generates waveform data Wi from a waveform generator, generates envelope data Ei that can be divided into a lower code P and an upper code Q from an envelope generator, and The waveform data W and the lower code P are added to the multiplier to obtain their product WPi, the product is added to a differentiator, the difference value between the two subsequent products is calculated, and the difference value is output. is added to the shifter and shifted according to the upper code Qi, so compared to the conventional envelope control device, it requires a multiplier and D
The scale of the A converter can be reduced.

Furthermore, in the calculation of the product WPiO difference value, if the upper code Q. changes, the change is corrected and the difference calculation is performed, so that a correct difference can be obtained.
.

[Brief explanation of drawings]

FIG. 1 is a block diagram for detailed explanation of the present invention;
FIG. 2 is a block diagram showing another example for explaining the present invention in detail, FIG. 3 is a diagram showing an example of envelope data used in FIGS. 1 and 2, and FIG. 4 is a block diagram showing another example of envelope data used in FIGS. A diagram showing an example of the format, FIG. 6 is a block diagram showing yet another example of the present invention without detailed explanation, FIG. 7 is a diagram showing an example of a shifter used on each side,
FIG. 8 is a block diagram of an embodiment of the present invention configured to output a difference value, and FIG. 9 is a block diagram of the embodiment of FIG. 8 in which the DA converter is configured as a floating format ODA converter. 10 and 11 are diagrams showing the code table of FIG. 9. 1... Waveform generator, 2... Envelope generator, 6... Multiplier, 8... Shifter, 9... DA conversion 10... Analog shifter. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 (B) 4 Ji'tan 8ji'S L t1 Shoulder T4 (Figure 5 Figure 9 Figure 10 Figure 10 rssB Figure 11 NSB +000 Two Dew 1000 -1i2 IOQ 0 -61 1 0 0 Q -601000 54I OOD -581000 -6'l I OOO -% I OOI -j15i0OI -, 54 + 0 0 1-53
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1101 , -2o1101 1iQ1 :l I lo chant 71iOi'

Claims (1)

[Claims] 0) Generate waveform data from a waveform generator, generate envelope data that can be divided into a lower code and an upper code from an envelope generator, and add the waveform data and the lower code to a multiplier. Obtain their product, add the above result to the difference machine, calculate the difference value of the following two products, add the output of the above difference value to the shifter, and shift this difference value according to the above upper code group. envelope controller. (2) The envelope control device according to claim 1, wherein in calculating the difference value, when the code changes, the change is corrected and the difference calculation is performed.