JP2009130767A - Signal processing device - Google Patents

Abstract

The conventional configuration is configured to focus (zoom) on sound by changing the directional characteristics of a directional microphone using in-focus information. Since there is a time difference between the arrival time of the video and the arrival time of the audio, there is a problem that the video and the audio are not synchronized.
A zoom control unit that performs zoom control of an image and a zoom of an audio, an audio zoom processing unit that performs zooming of an audio based on a zoom control signal from the zoom control unit, and an image generated by the zoom control unit. A focus processing unit 6 that performs focus control according to the zoom, and an audio signal delay unit that calculates the distance to the subject from the focus control result by the focus processing unit 6 and delays the audio signal according to the distance to the subject 3.
[Selection] Figure 1

Description

  The present invention relates to a signal processing device built in a video camera, a voice recorder, or the like.

  In recent years, a microphone device that uses a microphone that can control the directional characteristics, changes the directional characteristics of the directional microphone in synchronization with the focus of the camera on the subject, and focuses (zooms) the subject is used. (For example, refer to Patent Document 1).

  Hereinafter, a conventional microphone device will be described with reference to the drawings.

  As shown in the block diagram of FIG. 7, the distance between the camera and the subject A, that is, the focus distance, is detected by the focus distance detection unit 42 based on the output of the focus distance measurement sensor 41.

  The sound is collected by the microphone array 43, and the sound signal output from the microphone array 43 is subjected to focusing signal processing (zoom processing) by the sound signal focus processing unit 44.

  In addition, the video signal focus processing unit 45 outputs a focus control signal based on the detected focus distance, controls the zoom motor so that the focal length of the lens becomes the position of the subject A, and outputs the video signal via the lens. Trying to get. This video signal is subjected to electronic zoom processing by the video signal focus processing unit 45 as necessary, and then output from the video signal focus processing unit 45 to a recording medium.

  The zoom motor is provided with an encoder 46 for detecting the amount of deviation. The zoom magnification detection unit 47 detects the zoom magnification based on the output of the encoder 46, and the gain control signal detection unit based on the zoom magnification. 48 calculates the gain control signal, and the audio signal focused by the audio signal focus processing unit 44 is automatically gain controlled by an AGC (auto gain control) circuit 49 based on the calculation result.

According to the recording device of this video camera, automatic gain control is performed by the AGC circuit 49 in accordance with the zoom magnification, the sound level of the subject far away is increased, and the distance to the subject received from the video and the sound are received. The gap between the distance to the subject can be reduced, the sense of incongruity between the image and the sound level can be eliminated, and a more realistic recording can be achieved.
Japanese Patent Laid-Open No. 5-308553

  However, the conventional configuration is configured to focus (zoom) on the sound by changing the directivity characteristics of the directional microphone using the focus information. Since there is a time difference between the arrival time of the video and the arrival time of the audio, there is a problem that the video and the audio are not synchronized.

  In order to solve the above problems, the signal processing device of the present invention includes an imaging unit that captures a subject, a microphone that collects sound, a distance calculation unit that calculates a distance to the subject, and the distance calculation unit. And a signal delay unit that delays the video signal output from the imaging unit or the audio signal output from the microphone based on the distance calculated in (1).

  It is possible to synchronize video and audio by calculating the distance to the subject and adjusting the amount of data delay in the signal delay unit mounted in the signal processing device according to the distance. With advantages.

  Embodiments of a signal processing apparatus according to the present invention will be described below with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 shows an appearance of the video camera 100 according to the present embodiment. The video camera 100 can convert video and audio into data and record it as video information and audio information on the recording medium 10.

  Video and audio are acquired by an imaging optical system (not shown) and the microphone unit 1 provided in the video camera 100.

  FIG. 2 is a block diagram showing the configuration of the video camera 100 according to the present embodiment.

  The video camera 100 includes a microphone unit 1, an audio zoom processing unit 2, an audio signal delay unit 3, an imaging unit 4, a zoom control unit 5, a focus processing unit 6, and an operation unit 7.

  Hereinafter, each component will be described.

  The microphone unit 1 acquires sound. The microphone may be any of monaural, stereo, and multichannel.

  The audio zoom processing unit 2 controls the audio signal from the microphone unit 1 to an audio level corresponding to the zoom operation in response to the zoom control signal from the zoom control unit 5.

  The audio signal delay unit 3 delays the audio signal according to the distance to the subject calculated by the focus processing unit 6 and then outputs the audio signal to an audio signal processing unit (not shown).

  The imaging unit 4 captures a subject and outputs a video signal.

  The operation unit 7 is used when the photographer performs various operations such as zooming.

  The zoom control unit 5 outputs a zoom control signal to the audio zoom processing unit 2, the imaging unit 4, and the focus processing unit 6 in response to a zoom operation performed by the photographer using the operation unit 7.

  The focus processing unit 6 receives the zoom control signal from the zoom control unit 5, outputs a focus control signal corresponding to the zoom of the video to the imaging unit 4, and converts the video signal from the imaging unit 4 to the video signal processing unit ( (Not shown).

  The operation of the video camera 100 composed of the above components will be described.

  When video / audio is recorded by the video camera 100, the video signal captured by the imaging unit 4 is recorded for the video, and the audio signal acquired by the microphone unit 1 is recorded for the audio to the signal processing unit of the video camera 100. Entered.

  In the internal processing of the video camera 100, the processing time required for the audio signal processing can be ignored, whereas the processing time required for the video signal processing is in the imaging unit 4, the focus processing unit 6, and the video signal processing unit in the subsequent stage. The video signal processing causes a delay of about 45 ms in the video signal.

  Note that the delay amount of 45 ms depends on the internal processing speed of the video camera 100 and is not limited to this value.

  In order to cancel this delay and eliminate the gap between the video and the audio, the audio signal delay unit 3 synchronizes the video signal and the audio signal by delaying the audio signal by about 45 ms, which is the same as the video signal. .

  Here, when shooting a subject far away from the photographer, the photographer can use the zoom function of the video camera 100 to enlarge and record the subject. By the operation using the operation unit 7, the magnification to be enlarged is input from the zoom control unit 5 to the imaging unit 4, the audio zoom processing unit 2, and the focus processing unit 6.

  The video signal zoomed by the imaging unit 4 is input to the focus processing unit 6, and the focus processing unit 6 outputs a focus control signal based on the detected focus distance, and the focal length of the imaging unit 4 is the subject. The video signal is obtained via the imaging unit 4 and output to the video signal processing unit at the subsequent stage.

  The focus processing unit 6 calculates the distance from the imaging unit 4 to the subject at the same time when executing the focus processing.

  On the other hand, the audio signal is input to the audio signal delay unit 3 by increasing the audio level of the audio input from the microphone unit 1 in the audio zoom processing unit 2.

  However, since there is a large speed difference between the speed of the video signal and the audio signal, a time difference occurs between the video signal and the audio signal that reaches the video camera 100 that is shooting as the distance to the subject increases. As a result, the video and audio will be misaligned.

  In general, the speed of an audio signal in the air can be expressed by (Equation 1) when the temperature is t, and is generally known to be about 340 m / s.

Speed of sound [m / s] = 331.5 + 0.61 × t (Formula 1)
On the other hand, the speed of the video signal is 299792458 [m / s], and considering the shooting distance with the normal video camera 100, it is not necessary to consider the time difference, so the delay time of the audio signal is equal to the video signal and the audio. It can be considered as a delay time with the signal.

  Therefore, for example, when shooting a subject about 10 m away, if the sound speed is set to 340 m / s, a time delay of about 29 ms occurs in the arrival time to the video camera.

  This relationship is shown in FIG. As shown in FIG. 3, since the audio delay time changes according to the distance to the subject, it is necessary to manipulate the audio delay amount in the audio signal delay processing unit 3 according to this delay amount.

  FIG. 4 shows an example of control for calculating the audio delay amount based on the distance to the subject calculated by the focus processing unit 6 in the audio signal delay unit 3.

  For example, when the distance to the subject is 10 m, the audio delay time is about 29 ms as described above. Therefore, in the audio signal delay unit 3, from the delay time (about 45 ms) originally generated by the video signal processing, By subtracting the audio delay time (about 29 ms) and delaying the audio by about 16 ms, it becomes possible to match the gap between the video signal and the audio signal, and to match the gap between the video signal and the audio signal. By recording the recorded signal, it is possible to reproduce a signal in which there is no deviation between the video signal and the audio signal during reproduction.

(Embodiment 2)
FIG. 5 is a block diagram illustrating a configuration of a video camera 100 according to another embodiment. In FIG. 5, the same constituent elements as those in the first embodiment are given the same numbers, and description thereof is omitted.

  The signal delay unit 8 delays the video signal or the audio signal according to the distance to the subject calculated by the focus processing unit 6, and then the video signal processing unit (not shown) and the audio signal processing unit (see FIG. The video signal and the audio signal are output to (not shown).

  The operation of the video camera 100 will be described focusing on differences from the first embodiment.

  FIG. 6 shows an example of delay control based on the distance to the subject calculated by the focus processing unit 6 in the signal delay unit 8.

  In FIG. 6, when the distance to the subject is Tm or less, the delay amount of the video signal processing inside the video camera 100 is larger than the delay amount of the audio signal due to the distance. The input audio signal is delayed and output to the audio signal processing unit. On the other hand, the video signal is output to the video signal processing unit without being delayed.

  When the distance to the subject exceeds Tm, the delay amount of the audio signal due to the distance becomes larger than the delay amount of the video signal processing inside the video camera 100. Therefore, the signal delay unit 8 uses the input video for the difference. The signal is delayed and output to the video signal processing unit. On the other hand, the audio signal is output to the audio signal processing unit without being delayed.

  As described above, the signal delay unit 8 can delay the video signal or the audio signal in accordance with the distance to the subject, thereby making it possible to match the deviation between the video signal and the audio signal. By recording a signal in which the signal shift is matched, a signal in which the video signal and the audio signal are not shifted can be reproduced even during reproduction.

  The signal processing apparatus of the present invention is useful as an audio signal sound collection apparatus such as a video camera.

The figure which shows the external appearance of the video camera by one Embodiment of this invention. The block diagram of the signal processing apparatus in one Embodiment of this invention The image figure which shows the relationship between the distance to a to-be-photographed object and the delay amount of an audio | voice signal in one Embodiment of this invention. The image figure which shows the distance to a to-be-photographed object and the audio | voice signal delay amount in an audio | voice signal delay part in one Embodiment of this invention. The block diagram of the signal processing apparatus in other embodiment of this invention. The image figure which shows the distance to a to-be-photographed object and the signal delay amount in a signal delay part in other embodiment of this invention Block diagram of a conventional audio signal processing device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microphone unit 2 Audio | voice zoom process part 3 Audio | voice signal delay part 4 Imaging part 5 Zoom control part 6 Focus process part 7 Operation part 10 Recording medium 100 Video camera

Claims (3)

An imaging unit for photographing a subject;
A microphone that collects audio,
A distance calculation unit for calculating a distance to the subject;
A signal delay unit that delays a video signal output from the imaging unit or an audio signal output from the microphone based on the distance calculated by the distance calculation unit;
A signal processing apparatus comprising: An audio zoom processing unit for emphasizing audio from the subject collected by the microphone based on the distance calculated by the distance calculation unit;
The signal processing device according to claim 1, wherein the signal delay unit delays a video signal output from the imaging unit or an audio signal output from the audio zoom processing unit. A zoom control unit for zooming the subject;
A focus control unit that performs focus control corresponding to the zoom of the subject by the zoom control unit,
The signal processing apparatus according to claim 1, wherein the distance calculation unit calculates a distance to the subject from a result of focus control by the focus control unit.

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