JPH0632017B2 - Pitch control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pitch control device, and more particularly to a pitch control device that controls a pitch between an original sound and a reproduced sound by changing a frequency of an audio signal.

2. Description of the Related Art Conventionally, in this type of device, as shown in FIG. 1, the pitch of an audio signal input from an input terminal 1 is controlled by a pitch control circuit 2 so that the pitch is controlled and the output terminal is directly output. It was being output via 3. That is, when the frequency of the input signal is f, an output signal having a frequency of K · f is obtained at the output end of the pitch control circuit 2. For example, if the input signal of 440 Hz is raised by a semitone, K≈1.06, and therefore 466.2 Hz
Will be obtained.

In the conventional pitch control device thus configured, the output signal is obtained by directly shifting the frequency band of the input signal, so that the balance of the sound is disrupted in a frequency distribution when the pitch is greatly changed. There was a drawback. That is, when the original sound has a frequency component of 100 Hz to 10 KHz, if this signal is doubled, the frequency component of the output signal becomes 200 Hz to 20 KHz, and if this output signal is directly heard as a reproduction output, The bass range will be insufficient. Also, 1/2
If the frequency is doubled, the frequency component will be 50 Hz to 5 KHz, and the high frequency range will be insufficient.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks of the conventional ones, and an object of the present invention is to provide a pitch control device capable of controlling the pitch while appropriately maintaining the balance of the sound in terms of frequency. And

The pitch control device according to the present invention, in order to compensate for the lacking frequency band when the pitch is controlled, when increasing the pitch of the original sound, it generates a subharmonic of the frequency component of the low range of the pitch-controlled original sound. When the pitch of the original sound is superposed and lowered, the harmonics of the frequency components of the high tone range of the original sound whose pitch is controlled are generated and superposed.

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

FIG. 2 is a block diagram showing an embodiment of the present invention.
In the figure, in the pitch control circuit 2, the frequency of the input signal is multiplied by K or 1 / K (1 ≦ K ≦ ∞) as in the conventional example.
By doing so, the pitch is controlled. As the pitch control circuit 2, for example, Japanese Patent Application No.
The one proposed in 9-30996 can be used. The output signal of the pitch control circuit 2 serves as one input of the adder 4 and is supplied to the harmonic generation circuit 7 and the subharmonic generation circuit 8 via the HPF (high-pass filter) 5 and the LPF (low-pass filter) 6. It HPF5 is the pitch control circuit 2
For extracting the frequency component of the high frequency range from the output signal of the above and supplying it to the harmonic generation circuit 7 of the next stage. The LPF 6 extracts the frequency component of the low frequency range of the output signal and lower harmonics of the next stage. It is for supplying to the generation circuit 8.

The harmonic generation circuit 7 is for generating a high frequency range of 2n times (n = 1 to ∞) of the high frequency component extracted by the HPF 5, and is configured by connecting a plurality of multipliers in series, for example. To be done. Further, the subharmonic generation circuit 8
1/2 of low frequency component extracted by LPF6
It is for generating subharmonics of m times (m = 1 to ∞), and is configured by connecting a plurality of 1/2 frequency dividers in series, for example. Harmonic generation circuit 7 and subharmonic generation circuit 8
One of the output signals of 1 is selected by the selection switch 9 and becomes the other input of the adder 4. Selection switch 9
Is a control signal issued from a controller in the pitch control circuit 2 according to a command to increase or decrease the pitch.
Normally, the control is switched to the subharmonic generation circuit 8 side when raising the pitch, and to the harmonic generation circuit 7 side when lowering the pitch. Alternatively, the selection switch 9 may be directly controlled by a command signal, which is supplied from the outside to the pitch control circuit 2 and indicates whether the pitch is raised or lowered. In the adder 4, the harmonic signal or the subharmonic signal selected by the selection switch 9 is superimposed on the output signal of the pitch control circuit 2.

Next, the operation of the pitch control device according to the present invention will be described.

First, suppose that the original sound has a frequency component of 100 Hz to 10 KHz and the pitch is doubled. At this time, the selection switch 9 is switched to the subharmonic generation circuit 8 side. By doubling the pitch, the output signal of the pitch control circuit 2 has a frequency component of 200 Hz to 20 KHz. If this output signal is used as it is for reproduction output, the bass range will be insufficient. However, in the present invention, the low-frequency component of the output signal of the pitch control circuit 2 is set to the LPF.
The subharmonic generation circuit 8 extracts the subharmonic, and the subharmonic generation circuit 8 obtains the subharmonic, and the adder 4 superimposes the subharmonic on the output signal of the pitch control circuit 2 to supplement the insufficient frequency band. As a result, it is possible to reproduce a sound having a balanced frequency distribution.

When the pitch is halved, the pitch control circuit 2
Output signal becomes a frequency component of 50Hz-5KHz,
Since the high frequency range becomes insufficient, the HPF 5 and the harmonic generation circuit 7 generate a harmonic component of 5 KHz or more and superimpose it on the output signal of the pitch control circuit 2 to replenish the lacking band, thereby increasing the frequency range. It is possible to reproduce a well-balanced sound.

In the above embodiment, the signal processing for supplementing the frequency band is performed at the stage of analog signals, but it is also possible to perform the signal processing at the stage of digital signals, as shown in FIG. In FIG. 3, the pitch control circuit 20 is
An A / D converter 10 for converting an analog audio signal input via the input terminal 1 into a digital signal, a controller 11 for generating various control timing signals and analog signals, and a write address from the controller 11 R for storing a digital signal according to the read address and for outputting two different stored data according to the read address.
The RAM 1 includes an AM (random access memory) 12 and a crossfader 13 that crossfades two read data read from the RAM 12.
RAM12 for writing speed of digital signal to 2
The pitch between the original sound and the converted sound is controlled by changing the reading speed for reading the digital signal from, that is, changing the frequency of the audio signal.

The output signal of the pitch control circuit 20 is the digital filter 14
Via RAM 1 and one input of adder 15 and RAM1
6 is supplied. In the RAM 16, the pitch is controlled by storing and reading a digital signal according to the address signal from the controller 11, and the pitch control circuit 2
A signal for compensating for the insufficient band is generated by controlling the pitch at 0. 2 different address from RAM16
Two pieces of data are read out, crossfader is applied to these two pieces of data by the crossfader 17, and the output thereof becomes the other input of the adder 15 via the digital filter 18, and the pitch control circuit 20 passing through the digital filter 14 Is added to the output signal of. The output of the adder 15 is converted into an analog audio signal by the D / A converter 19 and becomes a reproduction output. By using the RAM 16 and the crossfader 17, it is possible to generate only a single order component such as only the second harmonic among the harmonics and the subharmonics.

According to this structure, unlike the embodiment shown in FIG. 2, it is not necessary to separately have the harmonic generation circuit 7 and the subharmonic generation circuit 8, and the pitch controller having the same structure as the original pitch control circuit 20. The effect of the present invention can be achieved only by providing the RAM 16 and the crossfader 17. In addition, cost reduction can be achieved by configuring the two-system pitch controller and adder as one digital IC.

As described above, according to the pitch control device of the present invention, when controlling the pitch of the original sound by changing the frequency of the audio signal, when the pitch is raised, the converted sound output from the pitch control means is output. The low harmonics of the low frequency range component of is generated by the generating means and superposed on the converted sound, and when lowering the pitch, the harmonic means of the high frequency component of the converted sound is generated by the generating means and converted into the converted sound. Since the frequency band lost by the pitch control is supplemented to the frequency band after the pitch control by superimposing, the pitch can be controlled while properly maintaining the balance of the sound in the frequency distribution.

[Brief description of drawings]

FIG. 1 is a block diagram showing a conventional example, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing another embodiment of the present invention. Description of main part numbers 2, 20 ... Pitch control circuit 4, 15 ... Adder 7 ... Harmonic generation circuit 8 ... Subharmonic generation circuit 9 ... Selection switch 12, 16 ... RAM 13, 17 ...... Cross fader

Claims (1)

[Claims] 1. A pitch control means for controlling a pitch between an original sound and a converted sound by converting a frequency of an audio signal, and a low tone frequency component of a low range of the converted sound when the pitch of the original sound is raised. When generating a wave and lowering the pitch of the original sound, it is provided with generating means for generating a harmonic of a frequency component in the high frequency range of the converted sound, and superimposing means for superimposing an output signal of the generating means on the converted sound. A pitch control device characterized in that