JPH06311583A - Video camera equipped with tone collector - Google Patents

Abstract

PURPOSE:To provide a wind noise suppression with high brightness function by discriminating whether a video camera is used indoors or outdoors from information with respect to brightness, and correcting the decided result of presence/absence of a wind noise. CONSTITUTION:A comparator 57 compares the integral value of a brightness signal from an integrator 56 with a reference exposure level REF, and outputs a differential voltage VD representing difference between them to an indoor/outdoor discrimination circuit 58. The circuit 58 is provided with a threshold value VT, and discriminates that the video camera is used indoors when the differential voltage VD is larger than the threshold value Vt, and that it is used outdoors when the former is smaller than the latter, and outputs discrimination signals S2 for them as L, H. When it is discriminated that the camera is used indoors at the circuit 58, no wind noise is generated, therefore, the output of an LPF 3 is outputted to an adder 8 without applying attenuation. When a control signal CS is set at an H level, it is judged that the camera is used outdoors and a large wind noise exists, and the output of the LPF 3 is attenuated by attenuation quantity decided in advance, then, it is outputted to the adder 8. An addition result is outputted to an output terminal 9 assuming that a countermeasure for the wind noise has been applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera equipped with a sound pickup device having a wind noise suppressing function.

[0002]

2. Description of the Related Art A problem with recording with a video camera is that the recording quality is extremely deteriorated due to wind noise during outdoor shooting. Therefore, conventionally, various proposals have been made regarding the method of suppressing the wind noise. Generally, for example, JP-A-64-20798 (H04R3 / 0)
As shown in 0), a method of comparing the high frequency band component and the low frequency band component of the microphone output and automatically controlling the sensitivity of the low frequency band based on the comparison result is used. ing.

The conventional technique will be described below.
In FIG. 4, 1 is a microphone and 2 is a microphone 1.
High-pass filter (HPF) for extracting the high-frequency component of the output of the, 3 is a low-pass filter (LPF) for extracting the low-frequency component of the output of the microphone 1, 4 is the HPF
High-frequency level detection unit for detecting output level, 5 is LPF
Low-frequency level detection unit for detecting output level, 6 is HPF
From the output and the LPF output, a determination unit that determines whether the output of the microphone 1 is a voice signal or wind noise, 7 is an attenuator that controls the gain of the LPF output by the determination unit 6, and 8 is the output of the HPF 2 and the output of the attenuator 7. Adder for adding and, 9 is adder 8
It is an output terminal for outputting the output to the recording unit in the subsequent stage.

Next, in FIG. 5, AU is the spectrum of the output signal of the microphone 1 when voice is input, and N is the spectrum of the output signal of the microphone 1 when wind noise is input.
From the comparison between spectrum AU and spectrum N in FIG. 5,
It can be seen that the wind noise spectrum is concentrated in the low frequency band. Therefore, in order to determine whether the signal is a voice signal or wind noise, the frequency spectrum of the signal may be examined.

In this prior art, the microphone 1
The HPF2 and the LPF3 separate the output of the high frequency signal and the low frequency signal. The signals in the two frequency bands are input to the high band level detection unit 4 and the low band level detection unit 5, and the levels of the respective frequency band signals are detected. These two signal levels are input to the determination unit 6, and when the level of the low frequency signal is much higher than the level of the high frequency signal, it is determined to be wind noise. That is, when the value obtained by dividing the level of the low frequency signal by the level of the high frequency signal is less than or equal to a preset threshold value, it is determined as an audio signal, and when the value is greater than or equal to the threshold value, it is determined as wind noise.

Next, a determination signal indicating the above determination result is supplied to the attenuator 7, and the attenuation amount of the attenuator 7 is controlled. That is, the attenuator 7 outputs the LPF 3 output to the adder 8 without attenuating when the wind is weak, that is, when the determining unit 6 determines that wind noise does not occur, and when the wind is strong, that is, the determining unit 6 When it is determined that wind noise is occurring, L
The output of PF2 is attenuated and output to the adder 8.

In the adder 8, the output of the HPF 2 and the output of the attenuator 7 are added and output to the output terminal 9, so that the signal derived at the output terminal 9 can suppress the influence of wind noise.

[0008]

The spectrum of the output signal when wind noise is input is concentrated in the low frequency band as shown in FIG. However, with general voices other than wind noise,
It cannot be said that there is nothing that has such a spectral distribution. For example, human voices also differ from person to person, and may include many low-frequency components. Therefore, according to the conventional technique, even when such a human voice is input to the microphone, it is determined to be wind noise, and as a result, the low frequency sound is cut, and the original characteristics cannot be sufficiently brought out. Occurs.

[0009]

DISCLOSURE OF THE INVENTION The present invention focuses on the fact that wind noise is generated only outdoors in the wind, and means for discriminating whether the video camera is used indoors or outdoors from the information on the brightness. Is provided, and the determination result of the presence or absence of wind noise in the above-mentioned conventional technique is corrected based on the determination result.

[0010]

Since the present invention is configured as described above, at least indoors, even if an audio signal containing a large amount of low frequency band components is input from a microphone, it is erroneously determined as wind noise and the original audio signal is obtained. It is possible to minimize the inconvenience of removing the low frequency components existing in the.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of the sound collecting device in this embodiment. The same parts as those in FIG. 4 showing the prior art are designated by the same reference numerals and the description thereof will be omitted.

Similar to FIG. 4, the output of the microphone 1 is
It is input to HPF2 and LPF3, and high frequency components and low frequency components are extracted. Furthermore, these frequency components are
The high-frequency level detection unit 4 and the low-frequency level detection unit 5 respectively input the high-frequency component level AH and the low-frequency component level AL, which are input to the first determination unit 16.

The first judging section 16 has the same function as the judging section 6 of FIG. 4, and the value AL / AH obtained by dividing the low frequency signal level AL by the high frequency signal level AH is calculated in advance. When it is less than or equal to the set threshold value, the determination signal S1 which is an output is at L level, and when it is at least the threshold value, the determination signal S1 is at H level. The determination signal S1 is input to the second determination unit 10.

The second control unit 10 adjusts the attenuation amount of the attenuator 7 based on the determination signal S1 and the determination signal S2 from the indoor / outdoor determination circuit 58 described later.

The indoor / outdoor discrimination circuit 58 discriminates between indoors and outdoors based on the exposure adjustment signal of the video camera. Therefore, the exposure adjustment system will be described. In the image pickup system of the video camera, incident light that has passed through the lens 51 and the optical diaphragm mechanism 60 is imaged on a solid-state image pickup device (CCD) and photoelectrically converted, and an image pickup signal obtained as a result is input to the color separation circuit 53. hand,
Create three primary color signals of red (R), green (G), and blue (B),
This is input to the camera process and matrix circuit 54, converted into a luminance signal Y and color difference signals RY and BY, and supplied to a video circuit 55 which performs various kinds of video signal processing. In the exposure adjustment operation, the brightness signal obtained as described above is integrated over a predetermined period, for example, one field period, and the integrated value is compared with the reference exposure level REF capable of realizing the optimum exposure state by the comparator 57. , The difference voltage VD indicating the difference between the two is output, the difference voltage VD is applied to the iris motor 59 to drive the motor, and the driving force adjusts the diaphragm amount of the optical diaphragm mechanism 60, and the integration circuit output is obtained. The brightness of the image pickup screen is maintained at a constant level by matching the reference exposure level. That is, as shown in FIG. 3, when the integrated value of the luminance signal increases, the difference voltage VD decreases, and the optical diaphragm mechanism 60 operates in the closing direction to reduce the amount of light incident on the CCD 52. On the contrary, when the integral value becomes smaller, the difference voltage VD becomes larger, and the optical diaphragm mechanism 60 operates in the opening direction to increase the amount of light incident on the CCD 52.

The differential voltage VD in the exposure adjusting system thus constructed is supplied not only to the iris motor 59 but also to the indoor / outdoor discrimination circuit 58. In the indoor / outdoor discrimination circuit 58, as shown in FIG.
When the input difference voltage VD is larger than the threshold value Vt, the discrimination signal S2 which is an output is considered to be in the indoor photographing state and is set to the L level. When it is small, it is considered that the outdoor photographing state is set, and the determination signal S2 is set to the H level. here,
The threshold value Vt corresponds to the difference voltage when the integrated value of the luminance signal becomes Yt, corresponds to the upper limit value of the integrated value of the luminance signal that occurs during indoor shooting, and is set in advance based on experiments.

The determination signal S1 from the first determination unit 6 and the determination signal S2 from the indoor / outdoor determination circuit 58 are both input to the second determination unit 10. The second determination unit 10 sets the output control signal CS to the H level only when both the determination signal S1 and the determination signal S2 are at the H level, and otherwise sets the control signal CS to the L level. Here, the determination signal S1 is the result of performing indoor / outdoor discrimination based on the magnitude of the low-frequency component as in the conventional example. Since a large number of cases are included, the H-level control signal CS indicating the outdoors can be output only when it is confirmed that the outdoors shooting is performed based on the luminance signal.

The control signal S is sent to the attenuator 7 to control the amount of attenuation. That is, when the control signal CS is at the L level, that is, when the first discriminating unit 16 determines that the output of the microphone 1 has a low low frequency component, or when the low frequency component is large, the attenuator 7 is used indoors or outdoors. When the determination circuit 58 can determine that the indoor shooting is performed, wind noise does not occur, and therefore the output of the LPF 3 is output to the adder 8 without being attenuated. When the control signal CS is at the H level, the outdoor operation is performed. The output of the LPF 3 is attenuated by a predetermined attenuation amount and is output to the adder 8 on the assumption that the influence of wind noise is strong during the shooting. The adder 8 adds the output of the HPF 2 and the output of the attenuator 7, and outputs the addition result from the output terminal 9 to the recording circuit in the subsequent stage as the output of the microphone 1 against which wind noise is taken.

In the above embodiment, the indoor / outdoor discrimination circuit 58 receives the difference voltage VD as the comparison result of the comparator 57, and the indoor / outdoor discrimination is performed based on the level of the difference voltage VD.
Instead of this, as shown in FIG. 2, the integrated value of the luminance signal from the integrator 56 is directly input to the indoor / outdoor discrimination circuit 158,
The indoor / outdoor discrimination can be performed depending on whether the integrated value is larger or smaller than the integrated value Yt corresponding to the threshold value Vt. in this case,
When the obtained integrated value is smaller than Yt, the discrimination signal S2 is set to the L level because it is indoors, and when it is larger, the discrimination signal S2 is set to the H level because it is outdoors.

It goes without saying that the operation of each circuit described above can be processed by software using a microcomputer.

[0022]

As described above, according to the present invention, even if an audio signal containing a large amount of low frequency components is input from a microphone at least indoors, it is not erroneously determined as wind noise and the accuracy is improved. It is possible to realize a high wind noise suppression function.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention.

FIG. 2 is a circuit block diagram of another embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between an integrated value and a differential voltage in each example of the present invention.

FIG. 4 is a circuit block diagram of a conventional example.

FIG. 5 is a diagram showing a spectral distribution when wind noise is input and when a voice signal is input.

[Explanation of symbols]

 1 Microphone 2 HPF 3 LPF 4 High frequency level detection section 5 Low frequency level detection section 16 First determination section 58 Indoor / outdoor discrimination circuit 158 Indoor / outdoor discrimination circuit 7 Attenuator 8 Adder

Claims (1)

[Claims] 1. A microphone, a high-pass filter for extracting a high-frequency component of the microphone output, a low-pass filter for extracting a low-frequency component of the microphone output, and a high-pass level detection for detecting the level of the high-frequency component. A low frequency level detecting section for detecting the level of the low frequency frequency component, and determining whether or not the relative magnitude of the low frequency frequency component level with respect to the high frequency frequency component level exceeds a predetermined level. 1 determination means, indoor / outdoor determination means for determining whether indoor shooting or outdoor shooting based on information related to the image pickup luminance signal level, and the first determination means determines that the relative size exceeds a predetermined level. And an attenuating means for attenuating the output of the low-pass filter when the indoor / outdoor identifying means determines that the image is taken outdoors. Video camera comprising a sound collection device having an adding means for adding the path filter output and said damping means output.