JP2005223706

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DESCRIPTION JP2005223706
[Objective] To provide a recording apparatus compatible with surround reproduction used for
recording in a video camera. A recording apparatus 11 comprises microphones M1, ..., Mup
arranged to pick up voices from four or more directions, and voice output signals m1, ..., mup
outputted from the microphones. Audio synthesizing means 5 for synthesizing and generating
four channels of right front audio signal R, left front audio signal L, front center audio signal C
and surround audio signal S, and the audio signals R, L, C, S Matrix encoder 6 that performs
signal processing to convert 2-channel audio data Lt and Rt according to an arithmetic
expression, and audio data recording means 7 that records the output 2-channel Ltch and Rtch
audio data Lt and Rt on a recording medium , And at the time of reproduction, the audio data Lt
and Rt are read out and are synthesized by the matrix decoder 9 into audio signals Lo, Ro, Co, So.
Und signal processing becomes possible. [Selected figure] Figure 1
Video camera recording device
[0001]
The present invention relates to a surround playback compatible recording device used for
recording audio in a video camera.
[0002]
A conventional video camera (also referred to as a camcorder).
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In general, the recording device mounted on the video camera has one or two microphones for
picking up the sound in front of the video camera body, and the monaural recording or 2 for the
recording medium such as a magnetic tape or a disc is performed. Channel stereo recording is
being performed.
[0003]
For example, audio data recorded by two microphones that respectively pick up audio from the
front left and right disposed in a video camera main body can be recorded on a video tape or a
disc by simple L channel and R channel of two transmission paths. It is recorded.
[0004]
In such a conventional video camera recording device, the recorded audio data has only audio
signal information in the left and right direction, and the L / R 2-channel audio signal is only
reproduced as it is in 2-channel stereo. The playback sound is a sound that is lacking in reality.
[0005]
In this respect, as a well-known document on a multi-channel sound pickup device of a video
camera aiming at multi-channeling of voice of a video camera, for example, in [Patent Document
1] below, the output of four nondirectional microphones is synthesized into eight The eight
directional microphones are synthesized by inputting into the means, and a multi-channel stereo
signal (L channel, R channel, C channel, SL channel, SR channel) is synthesized from the eight
directional microphones. The technology of the sound device is described.
[0006]
Further, in [Patent Document 2] below, the audio output signals of three nondirectional
microphones mounted on a video camera are combined to form 3-2 method 5 channels (L
channel, R channel, C channel, SL channel A technique is described for implementing a sound
collection device for the (SR channel) stereo.
[0007]
By the way, to obtain a three-dimensional impression or presence of an acoustic space, such as a
sense of direction or depth of a sound source, is called a three-dimensional sound.
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Originally, this stereophonic sound should be regarded as a series of systems from the sound
pickup in the original sound field to the reproduction at the reproduction site, but in general, the
pre-recorded program source enhances the three-dimensional sound effect under various
reproduction conditions It is regarded as a technical problem of sound field reproduction to
reproduce.
[0008]
A stereophonic (so-called stereo) system using a plurality of transmission paths and a binaural
system in which sound is picked up by a dummy head microphone and listened to by
headphones are long known as techniques for sound field reproduction that enhances threedimensional sound effects.
Generally speaking, stereo means two-channel stereo, but four-channel stereo was put to
practical use in the 1970s, and in recent years the word of surround is generally used in the
sense of sound field reproduction in all circumferential directions Became.
[0009]
The 4-channel stereo includes a discrete system using 4 transmission lines and a matrix system
using 2 transmission lines.
[0010]
The matrix method was proposed by Shiver (US) in 1969, and has four input signals (signal Lf
from left front, signal Lb from left rear, signal Rf from right front, signal Rb from right rear) ) Is
distributed to the transmission 2 signal (Lt, Rt), and signal processing called decoding to
distribute the 4 output signals (Lf ', Lb', Rf ', Rb') again is performed.
In this matrix method, there is a problem that the channel separation is insufficient and the
signal to be localized in the rear center is reproduced to the front, so that Lb and Rb are in
antiphase relation to each other for the purpose of improving the rear localization. In order to
improve the channel separation, we have developed a logic scheme that detects the most
dominant channel momentarily and reduces the crosstalk output of the other channels, and later
on RM (Regular Matrix). Integrated as a method).
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The standards for each of the four channel stereo systems are summarized in EIJA technical file
STC-021 (1986).
[0011]
Next, in stereo technology for movies, stereo format (developed by Dolby Laboratories) that
encodes a 3-channel 4-channel signal into 2 channels using matrix technology in the late 1970s
and optically records using noise reduction technology It has been developed.
FIG. 6 is a conceptual view of this matrix stereo encoder, which adds center (C) and surround (S)
channels to left and right (L, R) channels, and performs signal processing of the following
equation. j means 90 ° phase shift.
[0012]
In the matrix decoder for reproduction, central (C ') and surround (S') signals are produced by
signal processing of Lt + Rt, Lt-Rt, but active / voltage controlled amplifier (VCA) technology is
used to obtain channel separation. A decoder is used. The reproduced surround signal S 'is
reproduced by a plurality of speakers disposed behind the movie theater. FIG. 7 is an example of
a block diagram of a prologic decoder having an adaptive matrix circuit that detects the priority
of signals reproduced from each channel and emphasizes directivity.
[0013]
Unexamined-Japanese-Patent No. 2002-223493
[0014]
JP 2002-232988 A
[0015]
In the future, with the increase in size of television receivers in homes and the spread of multichannel AV systems, multi-channel recording of three or more channels will be required even in
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video cameras that produce video and audio sources.
[0016]
However, since the conventional video camera itself presupposes two-channel stereo recording,
in order to support multi-channeling of three or more channels, it is necessary to change the
design of the basic recording system of the video camera recording device. It will be imminent.
In this respect, the aforementioned [Patent Document 1] and [Patent Document 2] disclose a
technology for realizing multi-channeling with a small number of microphones as a sound
collection device mounted on a video camera. The technique of how to record on a disc is not
disclosed.
[0017]
In addition, in the case of recording in a video camera that produces an audiovisual source, it is
important to listen to the binaural recording speakers.
According to the present inventors' biphonic research, it has been found that if the left and right
microphones are separated by 9 cm or more to collect human's hearing, stereo feeling of the
sound source of binaural signal can be obtained at the time of reproduction by a speaker.
[0018]
However, the width and width of the video camera, which is so small and thin enough to fit in the
present palm, is about several centimeters, and it is structurally difficult to place the microphone
on the video camera body at 9 cm or more left and right. Implementation is also difficult from the
viewpoint.
[0019]
Also, according to the inventor's experiments, human hearing is sensitive to the voice from above
and insensitive to the voice from below, and instead of the sound from behind or in addition to
the sound from behind, from above It has been found that a new pleasant surround feeling is
obtained such that the entire sound including not only the entire circumference but also the
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entire circumference can be obtained by collecting the sound of and using it as one of the input
signals of the sound synthesis means.
[0020]
In this point, in the conventional video camera, there is no idea of collecting the upper sound and
setting it as one sound source of surround sound synthesis processing.
[0021]
The present invention has been made in view of two-channel stereo recording of a conventional
video camera recording device in order to meet multi-channelization for sound field reproduction
of stereophonic sound of the video camera recording device.
[0022]
In order to solve the above problems, the present invention provides four or more microphones
M1, M2, M3, M4,... Disposed in the video camera 10 to pick up voices from at least four different
directions at the time of shooting. · · Mn and voice output signals m 1, m 2, m 3, m 4, ... m n
respectively output from the microphone are synthesized, and a voice signal R from the right
front with respect to the shooting direction, and from the left front An audio signal of four
channels (Rch, Lch, Cch, Sch) composed of an audio signal L, an audio signal C from the front
center, and a surround audio signal S from a direction different from the three directions is
generated. The speech synthesis means 5 and the four channels of speech signals R, L, C, S
output from the speech synthesis means 5 are converted to two channels of speech data Lt, Rt
according to a predetermined arithmetic expression. A matrix encoder 6 for performing signal
processing to be converted and outputting; and an audio data recording means 7 for recording
the audio data Lt, Rt of the two channels Ltch, Rtch output from the matrix encoder 6 on a
recording medium The recording device 11 of the video camera 10 is characterized.
[0023]
Since the recording device of the video camera according to the present invention is configured
as described above, (1) four channels or more can be obtained by matrix decoding at the time of
reproduction while the audio data to be recorded has the same two channels as the conventional
Multi-channel surround playback is possible, and a realistic sound is obtained.
(2) Without changing the basic recording system of the recording device of the video camera,
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audio data capable of surround reproduction can be recorded on the video camera together with
the video by the two-channel audio recording method.
(3) Since the voice picked up from above the video camera is used as one voice signal source for
voice synthesis, a novel surround effect is obtained, in which the whole is wrapped up than ever
before.
[0024]
An embodiment of a recording apparatus for a video camera according to the present invention
will be described based on the drawings.
The circuit configuration of the two-channel stereo recording apparatus in the conventional video
camera is a known technology, and therefore the description thereof is omitted, and the
explanation will be focused on the means of voice synthesis of the matrix circuit for sound
collection by the microphone and recording.
[0025]
FIG. 1 is a block diagram showing the configuration of a recording apparatus of a video camera
according to the present invention.
FIG. 2 is a perspective view of a video camera showing a first embodiment of the microphone
arrangement in the recording apparatus of the video camera according to the present invention,
and FIG. 3 is a perspective view of the video camera showing a second microphone arrangement
FIG. 4 is a perspective view of a small thin video camera showing a third microphone
arrangement, and FIG. 5 is a perspective view of the video camera showing a fourth microphone
arrangement.
[0026]
In FIG. 1 or FIG. 2, the video camera 10 is disposed in the video camera 10 so as to pick up voice
from at least four different directions at the time of shooting, for example, forward, right, left,
back and upper. The four or more microphones M1, M2, M3, M4, Mup and the audio output
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signals m1, m2, m3, m4, mup outputted from the microphones respectively are synthesized, and
the sound from the right front with respect to the photographing direction Audio that generates
an audio signal of 4 channels composed of a signal R, an audio signal L from the left front, an
audio signal C from the front center, and a surround audio signal S from a direction different
from the three directions. The sound data (L, L, C, S) of 4 channels output by the synthesis means
5 and the voice synthesis means 5 are divided into 2 channels of audio data L according to the
following predetermined operation formula. The matrix encoder 6 performs signal processing to
convert t and Rt, and the two-channel Ltch and Rtch audio data Lt and Rt output from the matrix
encoder 6 are recorded on a recording medium such as a magnetic tape or disk And the audio
data Lt and Rt of the two channels recorded on the recording medium at the time of reproduction
of the video camera 10, and audio of three or more channels is read out. The matrix decoder 9 is
configured to perform signal processing to be synthesized to signals, for example, the original
four channels Lo, Ro, Co, and So, and output the result.
[0027]
That is, sound from at least four directions is picked up using a plurality of four or more
microphones, and recorded along with the video on a recording medium such as a video tape or
an optical / magnetic disk (DVD-RW, DVD-RAM, HDD, etc.) At this time, matrix encoding
processing is performed on audio signals of four or more channels, and stereo recording is
performed as two-channel data.
[0028]
As a result, although the audio data recorded on the recording medium has the same two
channels as before, surround (multi-channel of three or more channels) reproduction becomes
possible by matrix decoding at the time of reproduction, and the reproduced sound has a sense
of reality It is obtained.
[0029]
As the voice synthesis means 5, for example, the voice synthesis means described in the abovementioned [Patent Document 1] is used.
Also, as the matrix encoder 6, a matrix stereo encoder as shown in FIG. 6 described above can be
applied.
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An arithmetic expression of signal processing of two channels in the matrix encoder 6 is
expressed, for example, by the following [Equation 2].
The coefficients of the following formula are set as appropriate.
[0030]
Incidentally, the matrix decoder 9 at the time of reproduction is a matrix decoder circuit (for
example, a prologic decoder of FIG. 7) which is a well-known technology established in stereo
technology in movie.
And the surround signal as well as the signal processing for simply returning the two-channel
audio data Lt, Rt read from the recording medium to the four-channel audio signals R, L, C, S
before encoding. It can also be output as a multi-channel including a plurality of surround signals
of five or more channels such as right rear, left rear, and upper.
[0031]
As described above, in the video camera recording apparatus of the present invention, a system
for two-channel stereo recording / reproduction with respect to the recording medium used in
the conventional video camera can be used as it is, and the microphone M1 ··· and the matrix
encoder 6 are added. And the reproduction can be performed by the matrix decoder 9 added
separately.
[0032]
Next, one of the features of the recording apparatus of the video camera according to the present
embodiment is that it includes a dedicated microphone Mup for picking up voice from above as
shown in FIG. 2 as an arrangement of microphones mounted on the video camera. ing.
[0033]
That is, in FIG. 1 or FIG. 2, the microphone Mup disposed in the video camera 10 is provided to
pick up the sound from above in the erecting video camera 10, and the audio output signal mup
of the microphone Mup is One sound source of speech synthesis by the speech synthesis means
5 is used.
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[0034]
As described above, this microphone Mup is a sound source for providing a three-dimensional
sound with a new comfortable surround feeling in which the whole is covered not only in the
entire circumference but also in the upper part as compared with the conventional full
circumference surround reproduction. It has become
[0035]
Next, in order to enhance the sense of stereo in the speaker listening of binaural recording, it is
important to arrange the left and right microphones M2 and M3 to be separated by 9 cm or
more, but the recording device of the video camera according to the present invention Is
characterized by the arrangement of
That is, as shown in FIG. 2, most of the present video cameras 10 are attached to the video
camera main body 10A at the hinge structure and other joints with an openable / closable screen
display section 10B, and also opens laterally during shooting. It is possible.
[0036]
Therefore, in the video camera 10 of FIG. 3, by disposing a microphone at the peripheral portion
of the screen display unit 10B, the screen display unit 10B is opened sideways to the video
camera main body unit 10A at the time of photographing. By doing this, the horizontal distance
to the left and right microphones M2 and M3 can be separated by 12 cm or more.
[0037]
Also in the small and thin video camera 20 as shown in FIG. 3, the microphones M2, M1, M4 and
M5 are disposed at the peripheral portion of the screen display unit 20B, so that the screen
display unit 20B can The horizontal distance between the left and right microphones M2 and M3
can be separated by 12 cm or more by opening the unit 20A.
[0038]
The attachment form of the microphones M1, M2, M3,... To the video camera may be, for
example, a plurality of microphones M1 for picking up front, rear, left, right and upper voices as
in the video camera 30 of FIG. The direction of sound collection may be arbitrarily changed by
rotatably attaching the microphone assembly 15 containing M2, M3, M4 and Mup in one
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housing to the video camera main body 10A with a universal joint or the like. .
[0039]
It is a block diagram showing composition of a recording device of a video camera concerning
the present invention.
FIG. 1 is a perspective view of a video camera showing a first embodiment of a microphone
arrangement in a recording device of a video camera according to the present invention.
FIG. 5 is a perspective view of a video camera showing a second microphone arrangement
according to the invention;
FIG. 7 is a perspective view of a small thin video camera showing a third microphone
arrangement according to the present invention;
FIG. 10 is a perspective view of a video camera showing a fourth microphone arrangement
according to the invention;
It is a conceptual diagram of the encoder of the matrix stereo system of a well-known technology.
It is a block diagram of the pro logic decoder of a well-known technology.
Explanation of sign
[0040]
5 voice synthesizing means 6 matrix encoder 7 voice data recording means 9 matrix decoder 10,
20, 30 video camera 10A, 20A video camera main body 11 recording device 15 microphone
group M1, M2... Microphone Mup Collects voice from above Microphones that make sound m1,
m2, m3, m4, mup Voice output signal Lt, Rt Two-channel voice data Lo, Ro, Co, So ··· Multi-
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channel output signal R Voice signal from the front right L Voice signal from the front left C
Audio signal from front center S surround audio signal
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