JPH0697399B2 - Rhythm component detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rhythm component detecting device in the audio device field.

2. Description of the Related Art In recent years, rhythm component detecting devices have been attracting attention in music education for children, rhythm tone correction for adults, and the like.

An example of the conventional rhythm component detecting device described above will be described below with reference to the drawings.

FIG. 6 shows a detecting means of a conventional rhythm component detecting device, and FIG. 7 shows its operation. In FIG. 6, 1 is a low frequency wave generator, 2 is a level comparator, 3 is a comparison level end,
Reference numeral 4 is an input signal, 5 is an output signal, 6 is an output signal of a low frequency wave filter, and the input signal 5 passes through the low frequency wave filter 1 to become an output signal 6 which is an input to the level comparator 2. a is a judgment level of the level comparator, and 7 is an inverter.

The operation of the rhythm component detecting device configured as described above will be described below.

First, as shown in FIG. 7, in order to extract only the internal low frequency component of the input signal 4, the signal waveform is as shown in FIG.
As shown in FIG. 6, the high-frequency component is removed, and the level comparator 2 outputs a digital signal. The output signal 5 is H at a level higher than the comparison level a and L at a level lower than the comparison level a.

Problems to be Solved by the Invention However, in the above configuration, when the signal level is lower than the comparison level a, the output signal 5 is L and the rhythm component cannot be detected. Further, in the case of a signal without low frequency components, the rhythm component cannot be detected because the signal level is lowered by the low frequency wave device, and it is difficult for the detected signal to recognize a strong beat.

In view of the above-mentioned problems, the present invention provides a rhythm component detection device that has a low input level and a small malfunction even when there are few low frequency components.

Means for Solving the Problems In order to solve the above problems, in the rhythm component detecting device of the present invention, a first level detector in which an automatic gain control device is added to a conventional level detector and a signal rising detector are provided. Which counts its output signal or the operation output of two detectors.
One counter means, a comparing means for comparing the outputs of the two calculating means for calculating the pitch from the count result, and a rhythm display means are provided.

Effect The present invention not only can digitize the signal to a low input level by the automatic gain control device according to the above-described configuration, but also emphasizes the strength by the calculation with the output in the detection of the rising portion of the signal and improves the accuracy of the pitch calculation unit. Accurate rhythm component detection is possible.

Embodiment A rhythm component detecting device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a level detector and a signal rising detector according to an embodiment of the present invention. In FIG. 1, 4 is the input signal 8,
14 is a low frequency wave device, 9 and 15 are automatic gain control devices 10 and 16, a level comparator, 11 is a comparison level terminal, and 12 is a low frequency wave device 8.
Output, 13 is a level detector output 17,18,19,20 is a flip-flop, 21,22 is a 4-input arithmetic unit (NAND), 23 is a 2-input arithmetic unit (NAND), 24 is a clock, 25 is 4 inputs Calculator output, 26 is resistance, 27 is capacitor, 28 is transistor, 29
Is a current converter, 30, 31 are current supply sources, 32 is a switch, 33
Is a Miller integrator, and 34 is a diode. The input signal 4 is applied to the low frequency wave 8 and the wave output 12 is connected to the negative input of the level comparator 10 to become the level detector output 13. The wave output 12 is also connected to the input of the wave filter 8 through the automatic gain controller 9. 25 is the output of the 4-input NAND21. On the other hand, the input signal 4 is applied to the low frequency wave detector 14, and its wave output is connected to the negative input of the level comparator 16. The output of the wave filter 14 is connected to the input of the wave filter 14 through the automatic gain control means 15. The output of the level comparator 16 becomes the Q output synchronized with the clock 24 by the flip-flop 17, and the Q output of the flip-flop 17 operates the switch 32 to convert the current change into digital and analog signals by the Miller integrator. Connected to the positive input. 4-input NA with each Q output of flip-flops 17-20 as input
The output of ND21 and the 2-input NAND23 which inputs the output of each 4-input NAND22 which inputs each output are connected to the diode 34 which forms the rectifier circuit, the resistor 26 and the capacitor 27, and the output is connected to the base of the transistor 28. Connected. The transistor 28 is connected to a current converter 29 whose emitter is connected to the ground and whose collector is connected to the power supply, and one of the power supply is connected to the switch 32, the other is connected to the ground and the other is connected to the switch 32 by the output of the converter 29. Connected to current source.

FIG. 2 shows a means for calculating the output of FIG. 1. In FIG. 2, 25 is the 4-input NAND output of FIG. 1, 13 is the level detector output, 35 is the input inverting type arithmetic unit, 36, 37 is counter means, 38 and 39 are pitch calculation means, 40 is comparison means, 41 is display means, 42 is storage means, 43 is input inversion type calculation output 4 inputs
NAND output 25 passes through counter means 36 and pitch operation means 38
Further, the pitch calculating means 38 is connected to an input inverting type arithmetic unit (AND) having the level detector output 13 and the 4-input NAND output 25 as inputs, and its output is connected to the pitch calculating means 39 through the counter means 37. Comparing means 4 with input of 39, 39 outputs
0 is connected to the display means 41. The counter means 36, 37 and the pitch calculating means 38, 39 are connected to the memory 42, respectively. FIG. 4 is a flowchart of execution of FIG.

The operation of the rhythm component detecting device configured as described above will be described below with reference to FIGS. 1 to 4.

FIG. 3 shows the operation state of FIGS. 1 and 2, and the input signal 4 becomes the waveform 12 from which the high frequency component is removed by the low frequency wave transformer 8.

b is the voltage at the comparison level end 11 of the level comparator 10. b
In comparison with FIG. 6a, the relative detection level can be lowered sufficiently by the amount of operation of automatic gain control. Since the detection level of the inverted output 13 of the level comparator 10 is lower than that of the conventional example, the pulse train increases, while the input signal 4 is the output that has passed through the low-frequency wave detector 14, the level comparator 16, the flip-flop 17, and the switch 32. The pre-value comparison type analog-to-digital converter composed of the Miller integrator 33 converts the data one clock before into an analog value (plus input of the level comparator 16) and the current output signal of the low-frequency wave detector 14 ( A digital value is output by comparison with the negative input of the level comparator 16. On the other hand, the flip-flops 17 to 20 are shift registers, and the 4-input NAND 21 outputs L when each Q output is H and the 4-input NAND 22 outputs L when each L output is H. The 2-input NAND 23 outputs H when either of the 4-input NANDs 21 and 22 outputs L. That is, the 2-input NAND 23 outputs the H signal when the output of the level comparator 16 continues to be H or L four times or more.

The inverted output 25 of the 4-input NAND 21 is shown in FIG. Further, the number of pulses of the operation (AND) output 43 of 13 and 25 is smaller than that of the conventional example shown in FIG. 6, and the difference in pulse width becomes remarkable.

FIG. 4 embodies the calculation method of FIG. If there is a signal 13 from the level comparator 10 and if there is a signal for a predetermined time or longer in step 44, the signal 43 of FIG. 3 is used. The counter means 37 carries out the calculation of 45 steps shown in FIG. 4. In 45 steps, the widths of the digitized waveforms, which are similar in width to each other, are sequentially compared and the widths from wide to narrow are compared. Count with a tolerance. This counting operation is performed for a fixed sampling time. This value is stored in the storage means 42. The pitch calculation means 39 is the storage means.
The data of 42 is extracted and the work of steps 46 and 47 of FIG. 4 is performed. In step 46, the 1 / n value of the pitch data is 8
Compute n that matches 0% or more, multiply by 1 so that the value of 1 / n is within a certain range, and majority-determine the value as the value of the past three times (N-3 to N) and output the result. The comparison means 40 makes the determination in step 51. (N-3 to N) is the result of the previous majority (N-4 to N-
1) If the result is the same, the previous value is held in step 52 and the display means 41 displays it. The display is calculated in step 54 so that the display lighting interval is 1 to 2 seconds. If the result in step 51 is different, set a new calculated value and set in step 54.
Is calculated so that the lighting interval is 1 to 2 seconds. 1-2
Seconds is an empirical value that is easy to detect rhythm.

If there is no signal for a certain period of time in step 44, 25 is used as the input signal and 48 steps of calculation are performed. 49 steps perform the same operation as 46 steps and 50 steps perform the same operation as 47 steps.

As described above, according to this embodiment, the level detector including the low frequency counter and the level comparator, and the previous value comparison type analog,
By providing an arithmetic unit at the two detector outputs of the signal rise detector composed of the digital converter, the shift register and the arithmetic unit, the rhythm component can be distinguished more remarkably.

Moreover, not only can the rhythm component be accurately detected by counting and calculating the signal rise detection means and its output and successively comparing the calculated data, but also for medley performances where the tempo changes during the song. Can also respond.

Fig. 5 shows a device that simply displays without using a computing device such as a microcomputer. 55, 57 are resistors, 56 is a light emitting diode, 58 is a light emitting diode, 59 is a transistor, and output 43 is a resistor 55 and a capacitor 56. The light emitting diode 58 is made to blink only when a constant signal is provided. Transistor 59 is a driver resistor
57 is a current limiting resistor.

Although the level detector and the rising detector are used in the present invention, two rising detectors using two low frequency wave detectors having different frequency bands may be provided.

Further, in step 51 of FIG. 4, the majority voting results are compared with each other, but the majority voting results may be output as they are.

Further, in the present invention, it takes several seconds until the detection, so the display may be turned on or off during that time.

As described above, according to the present invention, the level detector including the low frequency wave detector and the level comparator, the pre-value comparison type analog-to-digital converter, the signal rising edge detector including the shift register and the calculating means, and each detector output. By providing a means for calculating, it is possible to separate the rhythm component from other components in the music signal to facilitate the discrimination.

A rising detector, a first counter means, a first pitch calculating means having a first calculating means, a level detector, and a calculator which receives the outputs of the rising detector and a second calculator which counts the output thereof. Second including counter means and second arithmetic means
By providing the means for comparing the pitch calculating means with each other, the rhythm can be accurately detected even when the rhythm component is at a low level or disappears midway.

[Brief description of drawings]

FIG. 1 is a block diagram of a rhythm component detecting device according to an embodiment of the present invention, FIG. 2 is a block diagram of a rhythm component calculating unit according to the present invention, and FIG. 3 is a diagram showing detection waveforms according to FIGS. 1 and 2. 4, FIG. 4 is a circuit diagram showing an embodiment of the operation of FIG. 2, FIG. 5 is a diagram showing a simple display example of rhythm, FIG. 6 is a block diagram of a conventional rhythm detection device, and FIG. It is a figure showing the detection waveform by a prior art example. 8,14 ...... Low frequency wave device, 9,15 ...... Automatic gain control device, 1
0,16 …… Level comparator, 17-20 …… Flip-flop,
21,22 …… 4-input NAND, 23 …… 2-input NAND, 28 …… transistor, 33 …… Miller integrator, 36,37 …… Counter means, 38,39 …… Pitch computing means.

Claims (1)

[Claims] 1. A rising edge detection means for detecting the rising edge of a music input signal, a first counter means for counting the rising edge detection signal detected by the detection means, and an output of the first counter means for a certain period of time. First pitch calculating means for calculating the pitch between pulses corresponding to the rhythm of the input signal, level detecting means for detecting a signal above a certain level of the input signal, and level detecting for the level detecting means. An input inversion type arithmetic unit for inputting a signal and the rise detection signal, a second counter unit for counting the output of the arithmetic unit, and an output of the second counter unit for a certain period of time to correspond to a rhythm. Second pitch calculation means for calculating the pitch between pulses, storage means for storing the outputs of the first and second pitch calculation means, and the first and second pitch calculation means Comparing means for comparing the output of the pitch calculating means and each of the previous pitch calculating outputs stored in the storing means, and a display for displaying the output as a rhythm signal when the result of the comparison is the same as the previous pitch calculating output. And a rhythm component detecting device.