JPH01272979A - Pitch extracting device - Google Patents

Abstract

PURPOSE:To enable high-accuracy pitch extraction by obtaining the integral addition result of a counted value from an adding means with a coincidence signal sent from a comparing means. CONSTITUTION:An acoustic signal inputted to an acoustic signal input terminal 1 is binarized by a binarizing means 2, which is supplied to a clocking means 3. This means 3 clocks the time with a clock signal from a clock signal generating means 7 and while the clocked time Tn is latched by an output latch with the leading edge of the waveform of the output signal of the means 2, the clocking result is reset and clocking of a next cycle is started. Then a storage means 4 is stored with the clocked time Tn with the leading edge of the waveform of the output signal of the means 2 and then past clocked values are read out in order from a clocked time Tn-1. Those past clocked values Tn-1-Tn-m are compared by a comparing means 5 with the clocked time Tn in order and when the ratio of both clocked values is within a determined range, a coincidence signal is outputted and the clocked value of the means 4 is stopped from being read out. Further, an adding means 6 integrates the past clocked values read out of the means 4 and the integral addition result is latched by the output latch with the coincidence signal output of the means 5.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is directed to the transmission of audio signals such as various musical tones and voices.
-7 This relates to the chili extraction device.

Conventional technology In recent years, with the advancement of digital technology, various pitch extraction techniques have been proposed, including a technique for calculating autocorrelation of time waveforms and a cepnutrum technique. As a technique, a pitch extraction technique using polarity reversal detection is being considered.

The above-mentioned pitch extraction device will be described below with reference to the drawings.

FIG. 3 shows the configuration of a conventional pitch extraction device.

In FIG. 3, 9 is an audio signal input terminal, 10 is a bypass filter, 11 is a low-pass filter, 12 is an A/D converter that converts an analog audio signal into digital data, and 13 is an output from the A/D converter 12. A polarity reversal detection section 14 detects polarity reversal of digital data and outputs a polarity reversal detection signal, and a polarity reversal detection section 14 starts counting the pinch period according to the polarity reversal detection signal output from the polarity reversal detection section 13, or A control section outputs a timing instruction signal instructing the end, 15 is a timekeeping section that measures the pitch period of digital data in accordance with the timing instruction signal, and 16 is an output terminal.

The operation of the pitch extraction device configured as described above will be described below.

An acoustic signal input from a microphone or the like to the acoustic signal input terminal 9 has its direct current component removed by a bypass filter 1Q, and then passes through a low-pass filter 11 to undergo anti-aliasing filtering that satisfies the sampling theorem. The data is sequentially converted from analog to digital by the D converter 12 to become digital data.

Next, the polarity reversal detection section 13 detects the polarity reversal of the digital data sequentially output from the A/D converter 12, and then outputs a polarity reversal detection signal to the control section 14. Control part 1
4 outputs a timing instruction signal to the timing section 16 to instruct the start or end of timing of the pitch period according to the polarity reversal detection signal. Here, when the control unit 14 outputs a time measurement instruction signal instructing the start of time measurement, the time measurement unit 16 starts counting the number of samples of digital data, that is, starts timing the pitch period.

Furthermore, when a timing instruction signal instructing the end of timing is output from the control unit 14, the timing unit 16 outputs the number of samples up to that point, that is, the timing result, to the control unit 14 as a pitch period, and then resets the timing result.

By repeating the above operations according to the polarity reversal detection signal from the polarity reversal detection section 13, the pitch period of the digital data sequentially output from the A/D converter 12 is obtained.

In addition, the pitch period Ni side is the so-called pitch F1 (Hz:)
To convert to Fi [)!, use the sampling frequency Fs [Hz]. ', zl = Fs /Ni
−(1).

Problem to be Solved by the Invention However, with the above configuration, as is clear from equation (1), the accuracy of the pitch period obtained changes depending on the sampling frequency. In order to increase the sampling frequency, the sampling frequency must be kept high, which requires high-speed arithmetic processing, resulting in an expensive device.

In view of the above problems, the present invention provides a pinch extraction device that does not require high-speed arithmetic processing, has a simple configuration, and has high accuracy.

Means for Solving the Problem In order to achieve this object, the pitch extraction device of the present invention includes a binarization means for binarizing an acoustic signal, and a binarization means for binarizing an acoustic signal.
A clock means for clocking the period of the digitized audio signal, and sequentially storing the time values counted by the clock means,
A storage means capable of storing at least two or more timed values, and a range of values in which the timed value measured by the timed means and the timed value stored in the storage means are sequentially compared and the ratio of the two timed values is determined. Comparison means outputs a coincidence signal when the comparison means compares the time values stored in the storage means, and addition means accumulates the time values stored in the storage means compared by the comparison means. .

The device is configured to obtain a cumulative addition result of the count value from the means.

Effects of the present invention With the above-described configuration, an input acoustic signal is converted into a digital signal by the binarization means, and the period is timed by the timer means. The time value, which is the time measurement result, is stored in the storage means and is compared with the past time measurement result by the comparison means. Here, if there is a result that is almost the same as the past time measurement result, the cumulative addition value of the past time measurement value that is the subject of comparison is a value that corresponds to the pitch period of the input acoustic signal, and this is the value of the adder. It is latched to the output launch and output.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of a pitch extraction device according to an embodiment of the present invention, and FIG. 2 shows operational waveforms of the block diagram shown in FIG.

In Figure 1, 1 is an audio signal input terminal, 2 is a 7-pin
-7 Binarization means for binarizing the acoustic signal; 3 is a timekeeping means that is controlled by the output of the binarization means 2 and has an output latch (not shown); 4 is a timekeeping means that is the output of the timekeeping means 3; A storage means for storing the value, and a comparison means 5 for comparing the output of the timer 3 and the time value read out from the storage means 4, and outputting a coincidence signal when the ratio of both time values is within a predetermined range. ,6
Reference numeral 4 indicates an adding means (not shown) with an output latch that cumulatively adds the time value read from the storage means 4, 7 is a clock signal generating means, and 8 is an output terminal.

When the acoustic signal shown in FIG. 2(a) is input to the acoustic signal input terminal 1, the output signal of the binarization means 2 has the waveform shown in FIG. 2(b). The clocking means 3 is a clock signal generating means 7
Timing is performed using a clock signal supplied from the binarizing means 2, and at the rising edge of the waveform of the output signal of the binarization means 2, the clock value Tn, which is the timing result, is latched to the output launch, and the timing result is reset and the next period of timing starts. . FIG. 2 (Q) shows the output latch signal of the clock means 3. The storage means 4 stores the time value Tn at the rising edge of the waveform of the output signal of the binarization means 2, and then stores the time value Tn-+ as shown in FIG. 2(d).
Read past time values sequentially from . This past time value T
n-1, Tn-2..."" Tn-m is sequentially compared with the timed value Tn by the comparison means, and when the ratio of both timed values is within a predetermined range, the result shown in FIG. 2(e) is obtained. At the same time as outputting the coincidence signal, the storage means 4 stops reading out the time value. Further, the addition means 6 includes past time values Tn-1, Tn-2 read out from the storage means 4, as shown in FIG. 2 (0).
. . . Tn-□ is cumulatively added, and the cumulative addition result is launched into the output latch when the comparison means 5 outputs a match signal.

The output signal of the output lunch of the adding means 6 is shown in FIG. 2(g).

Output P of the output latch of the adding means 6. is a signal corresponding to the pitch period of the acoustic signal, and its relationship with the clock signal GK is as follows.It can be seen that if the pinch period is to be determined with high precision, the frequency of the clock signal should be increased.

9 ・＼−7 It's a trench. From Figure 2 (a), (b), and <g), the pitch period is To+T, , T, +T2. T2+
Since T3--, it is possible to prevent incorrect pitch extraction due to harmonics of the acoustic signal.

Effects of the Invention According to the present invention, the input acoustic signal is converted into a digital signal by the binarization means, and the period is timed by the timer means. The time value, which is the time measurement result, is stored in the storage means and is compared with the past time measurement result by the comparison means. Here, if there is a result that is almost the same as the past time measurement result, the cumulative addition value of the past time measurement value that is the subject of comparison is a value that corresponds to the pitch period of the input acoustic signal, and this is the value of the adder. Since it is latched to the output latch and output, it is possible to perform highly accurate pitch extraction with a cylindrical structure, and to prevent errors in pitch extraction due to harmonics of the acoustic signal or noise.

In addition, there is no need to perform high-speed calculation processing to improve pinch extraction accuracy, making it possible to implement the method using inexpensive hardware.

107, -2

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pitch extraction device according to an embodiment of the present invention, FIG. 2 is an exemplary waveform diagram of each data according to an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional pitch extraction device. It is. 1 acoustic signal input terminal, 2... binarization means, 3...
Timekeeping means, 4... Storage means, 5... Comparison means, 6
Adding means, end... Clock signal generating means, 8...
...output terminal, 9. -acoustic signal input terminal, 10.
Bypass filter, 11...Low pass filter, 12
...A/D converter, 13... Polarity reversal detection section, 14... Control section, 15... Time measurement section, 16...
・Output terminal.

Claims (1)

[Claims] A binarizing means for binarizing the audio signal, a clocking means for counting the period of the audio signal binarized by the binarizing means, and sequentially storing the time values measured by the clocking means, A storage means capable of storing at least two or more timed values, and a timed value measured by the timed means and a timed value stored in the storage means are sequentially compared, and a ratio of the two timed values is determined. Comparing means for outputting a coincidence signal when the values are within a range, and addition means for cumulatively adding the timed values stored in the storage means compared by the comparison means, the coincidence signal from the comparison means is provided. A pitch extracting device characterized in that a cumulative addition result of count values is obtained from an adding means.