JPH09322300

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DESCRIPTION JPH09322300
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
video and audio reproduction apparatus for reproducing video and audio such as DVD (digital
video disc), and more particularly to reproduction of a multichannel audio signal in a normal
channel or three channels. It relates to an improvement for sharing regeneration.
[0002]
2. Description of the Related Art As a system for reproducing DVD audio, there are a 2-channel
stereo system, an AC-3 multi-channel system of a complete 5-channel configuration proposed by
Dolby Laboratories, and other multi-channel systems. In 2-channel stereo reproduction, in
addition to 2-channel stereo signals, there are cases where center channel signal components are
generated and reproduced from the speaker provided at the center, and there are three channels
of reproduction environment where the center speaker is provided. .
[0003]
Therefore, according to the present invention, when reproducing video and audio, it is easy to
obtain compatibility with reproduction of multi-channel audio signals on three channels or
reproduction on five channels, and to the rear. An object of the present invention is to provide a
video and audio reproduction apparatus which can easily restore the original sound field even
when no speaker is prepared.
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[0004]
SUMMARY OF THE INVENTION In order to achieve the above object, a video and audio
reproduction apparatus according to the present invention is substantially symmetrical with
respect to a listener on a multichannel audio signal of video and audio including a pair of left and
right rear surround signals. And a demodulator for demodulating and separating the multichannel audio signal, and a demodulator for demodulating and separating the multi-channel
audio signal. It has a convolver with a set of filter coefficients based on the head related transfer
function for each channel of a pair of left and right rear surround signals, and filters to output
sound images at a substantially symmetrical position behind the listener. Sound image
localization means, adding the stereo signals of two channels demodulated and separated by the
demodulator to a center channel First adder for generating the noise component, an attenuator
for attenuating the output level of the first adder, a left / right pair through the sound image
localization means to the left / right pair of front stereo signals demodulated and separated by
the demodulator The second and third adders that supply the sum of the rear surround signals to
the pair of speakers arranged at the front position substantially symmetrical with respect to the
listener. The output of the attenuator is selected during stereo reproduction. And a signal
processing means having a changeover switch for selecting the center channel signal
demodulated and separated by the demodulator during AC-3 reproduction and supplying the
selected center channel signal to the speaker arranged in the center. .
[0005]
In the sound image localization means, the filter coefficients Hl and Hr are Hl = (SF-AK) / (S2-A2)
Hr = (SK-AF) / (S2-A2) (where S is received from a pair of speakers) Transfer function to the same
side ear of the listener, A is transfer function from a pair of speakers to the opposite ear of the
listener, F is transfer function from the position where the sound image is to be localized to the
same side ear of the listener K is provided with a pair of sound image localization filters set for
transfer functions from the position where the sound image is to be localized to the opposite ear
of the listener) for each channel of the pair of left and right rear surround signals, each channel
The filter output with the filter coefficient set to Hl and the filter output with the different filter
coefficients Hr of the other channels are added each time, and the pair of added outputs is
subjected to the filter processing for the left and right rear pairs It is characterized by outputting
as a surround signal.
[0006]
Furthermore, the sound image localization means includes a first adder for obtaining a sum
signal of the pair of left and right rear surround signals, a second adder for obtaining a difference
signal of the pair of left and right rear surround signals, and a filter coefficient P P = (F + K) / (S +
A) (where S is the transfer function from the pair of speakers to the same side of the listener, A is
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the transfer function from the pair of speakers to the other side of the listener, F is The transfer
function from the position where the sound image is to be localized to the same ear of the
listener, K is set to the transfer function from the position where the sound image is to be
localized to the opposite ear of the listener, A second filter processing the output of the second
adder, the first filter processing the output of the second filter, the filter coefficient N being set to
N = (F−K) / (S−A), and Obtaining a sum signal of the signals processed by the first and second
filters , And a fourth adder for obtaining a difference signal of the signals processed by the first
and second filters, wherein the third and fourth outputs are filtered to be a pair of left and right
rear surround It is characterized by outputting as a signal.
[0007]
DESCRIPTION OF THE PREFERRED EMBODIMENTS The First Preferred Embodiment The most
preferred embodiment of the present invention will be described below.
FIG. 1 is a block diagram showing a first embodiment of a DVD reproducing apparatus according
to the present invention.
In FIG. 1, 1 is a demodulator of AC-3 or 2 channels, and the digital signal stream is 5 channels of
2-channel stereo signals L and R, center channel signal C of 1 channel and rear surround signals
SL and SR of 2 channels. And the low frequency signal below 100 Hz.
Usually, the low band signal is reproduced by a super woofer or distributed to each channel, but
in this embodiment, the low band signal is omitted to make the description easy to understand.
[0008]
Also, 2 is a display means, for example, a television receiver, in which a stereo signal of 2 ch
demodulated or separated by the demodulator 1 or an AC-3 signal of 5 ch configuration is
arranged at a symmetrical position in front of the listener. A signal processing means for
reproducing from the stereo speakers 3L and 3R of the channel and the speaker 3C of the center
channel provided at the center of these speakers is shown, and the speaker 3L in either of stereo
reproduction or AC-3 reproduction, 3R and 3C are used.
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At the time of AC-3 reproduction, it is also possible to reproduce directly the signals of 5
channels of L, R, C, SL and SR which are demodulated and separated by the demodulator 1
respectively by speakers not shown.
[0009]
As the signal processing means 2, left and right sound image localization filters 21 a and 21 b
having a pair of convolvers with coefficients set based on head related transfer functions for each
channel of rear surround signals SL and SR, and similar right sides And sound image localization
means having left sound image localization filters 21c and 21d, an adder 21e for adding a stereo
signal L and R of two channels to generate a center channel signal component, and attenuating
the output level of the adder by 3 dB Attenuator 21 f, the signal demodulated and separated by
demodulator 1 selects the output of the attenuator 21 f on the p side during stereo reproduction
of two channels of L channel signal and R channel signal, and the signal demodulated and
separated by demodulator 1 Is the center from the demodulator 1 on the q side during AC-3
reproduction of a 5-channel configuration of L, R, C, SL, and SR. A selector switch 21g for
selecting the channel signal C, an adder 21h for adding the output signal of the left sound image
localization filter 21a and the output signal of the right sound image localization filter 21c to the
L channel signal of the stereo signal from the demodulator 1; The R channel signal of the stereo
signal from the demodulator 1 is added with an adder 21i for adding the output signal of the
right sound image localization filter 21b and the output signal of the left sound image
localization filter 21d.
[0010]
Here, sound image localization means, that is, a pair of sound image localization filters 21a and
21b, 21d and 21c provided on the left and right sides for each channel of the rear surround
signals SL and SR, as shown in FIG. Is processed to localize the sound image on the left and right
sides of the listener, respectively, using the ATAL-SCHROEDER (Atar-Scheer Radar) type filter that
cancels the spatial characteristics of, and is added to the front two-channel stereo signals L and R
respectively Do.
Furthermore, the ATAL-SCHROEDER type filter will be described in detail. FIG. 2 shows the
combination of the sound image localization filter and the crosstalk canceling filter array shown
in FIG. 6 configured for two sound images.
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[0011]
In other words, looking at one channel, the configuration is as shown in FIG. The configuration of
the sound image localization filter circuit shown in FIG. 6 includes a sound image localization
filter which is a portion into which characteristics F and K of the localization position are folded
and a crosstalk canceling filter array. The crosstalk canceling filter array portion is an ATALSCHROEDER filter. Equivalent to. In FIG. 6, S represents the transfer function from the
loudspeaker to the ear on the same side, while A represents the transfer function to the ear on
the opposite side. Since the speakers are symmetrical with respect to the listener, the transfer
function from each speaker to both ears is also symmetrical.
[0012]
The output signals X 'and Y' from the speakers LF and RF are X '= (SX-AY) / (S2-A2) Y' = (SY-AX)
/ (S2-A2). In order to perform sound image localization, a signal obtained by convoluting a
transfer function in a direction desired to be localized is input to the X and Y inputs. That is, X '=
[(SF-AK) / (S2-A2)]. X = Hl.xY' = [(SK-AF) / (S2-A2)] when X = Fx and Y = Kx. X = Hr-x, and sound
image localization is realized. The filter has these Hl and Hr as coefficients.
[0013]
Returning to FIG. 2, S is a transfer function from a pair of speakers to the same ear of the
listener, A is a transfer function from a pair of speakers to the opposite ear of the listener, F is
from the position where the sound image is to be localized The transfer function to the ear of the
same side of the listener, K indicates the transfer function from the position where the sound
image is to be localized to the opposite ear of the listener. Since the speakers are symmetrical
with respect to the listener, the transfer function from each speaker to the same ear is also
symmetrical. The outputs from the actual speakers 3L and 3R arranged at symmetrical positions
in front of the listener are X 'and Y'. In order to localize an arbitrary sound image around the
listener by the two front speakers 3L and 3R, the transfer function F and K from the position of
the target to be localized to the listener is processed to be convoluted with the input signal, and
then the front A process of canceling the space characteristic from the speakers 3L and 3R to the
listener is performed. First, the latter spatial property cancellation processing will be described.
[0014]
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The outputs x and y of the two ears by the speakers 3L and 3R arranged at symmetrical positions
ahead of each other are shown by x = SX '+ AY'y = AX' + SY ', and this output is an input X to the
cancellation filter. Since we want to be equal to Y, we can replace x, y with the inputs X, Y and
express X = SX '+ AY' Y = AX '+ SY', so based on this equation On the other hand, the outputs X
'and Y' from the speaker are X '= (SX-AY) / (S2-A2) (1.1) Y' = (SY-AX) / (S2-A2) (1. 2)
[0015]
Next, consider the convolution of the transfer function in the direction to be localized.
In FIG. 2, when the signal x is reproduced from the speaker (position Xp) on the rear left side of
the listener, the signal Fx in which the transfer functions F and K are convoluted in the left ear Lear and the right ear R-ear of the listener It becomes Kx. If this signal is applied to the above
inputs X and Y, sound image localization can be realized.
[0016]
That is, in FIG. 2, if X = Fx and Y = Kx and the equation (1.2) is input, then X ′ = [(SF−AK) / (S2A2)] × = Hl · x (2.1 ) Y '= ((SK-AF) / (S2-A2)) x = Hr x (2.2). Now, the convolution of the transfer
function and the cancellation processing of the space characteristic are summarized into the
filter coefficients H1 and Hr. This is the case where the speaker is at the rear left position Xp of
the listener, so in FIG. 2 the filter coefficient Hl points to the filter 21a, the filter coefficient Hr
points to the filter 21b and the original signal x is taken as its input. Similarly, in order to create
another sound image of the input signal y on the rear right side, the left and right filters are
interchanged and input as 21c and 21d because they are symmetrical.
[0017]
Therefore, in order to localize the sound image at two substantially symmetrical positions in front
of the listener, a pair of left and right sound image localization filters 21a and 21b provided for
each channel of the rear surround signals SL and SR, Sound image localization can be performed
by configuring 21 d and 21 c with four FIR filters having Hl and Hr as filter coefficients
represented by equations (2.1) and (2.2).
[0018]
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With the above-described configuration, when stereo reproduction of only two L channel and R
channel channels of the signal demodulated and separated from the demodulator 1 shown in FIG.
1 is performed, the selector switch 21 g is switched to the p side to obtain a two channel stereo
signal L The level of the output of the adder 21e that adds R to generate the center channel
signal component is reduced by 3 dB via the attenuator 21f, and the stereo speaker 3L, such as a
television, disposed at a front position substantially symmetrical with the listener. And 3R are
reproduced by the center channel speaker 3C arranged at the center, and the L channel and R
channel signals demodulated and separated from the demodulator 1 are respectively added to
the speakers 3L and 3R through adders 21h and 21i. It will be played back, and it will be played
on 3 channels.
At this time, only the two channels of L channel and R channel are demodulated and separated
from the demodulator 1, and the center channel signal C and the rear surround signals SL and SR
are not demodulated and separated. Therefore, the demodulator 1 separates them from the
adders 21h and 21i. No rear surround signal is added to the output.
[0019]
On the other hand, at the time of AC-3 reproduction in which the signal to be demodulated and
separated from the demodulator 1 shown in FIG. 1 has five channels of L, R, C, SL, and SR, the
demodulator is switched by switching the switch 21g to the q side. The center channel signal C
demodulated and separated in 1 is selected as it is and reproduced by the center channel speaker
3C disposed at the center of the stereo speakers 3L and 3R, and the two-channel stereo signals L
and R are adders 21h and 21i are reproduced as they are by stereo speakers 3L and 3R such as a
television set at a substantially left-right symmetrical front position with respect to the listener,
and the rear surround signals SL and SR are ATAL as shown in FIG. A pair of left and right sound
image localization filters 21a and 21 using filters of SCHROEDER type , 21c and 21d to localize
the sound image to the left and right of the listener respectively, and are added to the front twochannel stereo signals L and R via adders 21h and 21i, The listener can enjoy the movement
sound while being surrounded by the 5ch sound image while watching the television in front. In
particular, since the rear surround signals SL and SR are separate signals, a high sense of reality
can be obtained.
[0020]
In this manner, by switching the changeover switch 21g, compatibility with the reproduction of
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the multi-channel audio signal on three channels or the reproduction on five channels can be
easily obtained in reproducing the video and audio, and a rear speaker is provided. It is easy to
restore the original sound field even if you
[0021]
That is, as shown in FIG. 3 (A), as shown in FIG. 3 (B), only by providing a pair of speakers 3L, 3R
on both sides of the television receiver TV and providing a speaker 3C between the speakers.
Rear surround signals SL and SR are reproduced from the position, and stereo signals and center
channel signals from the front and rear stereo signals (rear surround) localized to the rear are
three-dimensional without installing a rear speaker. Can play back surround sound.
[0022]
Second Embodiment Next, FIG. 4 is a block diagram showing a second embodiment of the DVD
reproducing apparatus according to the present invention.
In the first embodiment described above, a filter for performing a pair of sound image
localization processing for each channel is required for the rear surround signals SL and SR, that
is, four sound images are localized in two places. A filter is required, the hardware scale becomes
large, and it can not be used for consumer products such as television receivers.
This second embodiment is effective when sound image localization is performed at symmetrical
positions with respect to the median plane that divides the head of the listener in left and right
symmetry, and the number of filters used is as shown in FIG. The above-mentioned problem is
solved by forming it with two halves.
[0023]
That is, in the second embodiment shown in FIG. 4, for example, a television in which a 2ch
stereo signal or a 5ch AC-3 system signal demodulated and separated by the demodulator 1 is
arranged at a symmetrical position ahead of the listener, for example As a signal processing
means 2 for reproducing from the two-channel stereo speakers 3L, 3R of the receiver and the
speaker 3C of the center channel, the rear surround signals SL, SR are subjected to signal
processing so as to localize the sound image to the rear of the listener. Sound image localization
circuit (shuffler filter) 22a for reproducing from the two-channel stereo speakers 3L and 3R, an
adder 22b for adding a two-channel stereo signal L and R to generate a center channel signal
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component, and an adder output level thereof Attenuator 22c that attenuates by 3 dB, and the
output of the attenuator 22c on the p side in stereo reproduction A selector switch 22d for
selecting and selecting the center channel signal C from the demodulator 1 on the q side in AC-3
reproduction, and the L channel signal of the stereo signal from the demodulator 1 via the sound
image localization circuit 22a Similarly, an adder 22e for adding the L channel signal of the
surround signal, and an adder 22f for adding the R channel signal of the rear surround signal via
the sound image localization circuit 22a to the R channel signal of the stereo signal from the
demodulator 1 Is equipped.
[0024]
In the above configuration, as the sound image localization circuit 22a, a shuffling (SHUFFLER)
filter as shown in Japanese Patent Application No. 6-197356 already proposed by the present
inventor et al. Is used.
The configuration of this shuffler filter is shown in FIG. In FIG. 5, 22a1 is a first adder for
obtaining a sum signal of the pair of left and right rear surround signals, 22a2 is a second adder
for obtaining a difference signal of the pair of left and right rear surround signals, and 22a3 is a
filter coefficient to be described later A first filter for setting P and processing the output of the
first adder 22a1, 22a4 is a second filter for processing the output of the second adder 22a2 with
a filter coefficient N to be described later set, 22a5 is a third adder for obtaining a sum signal of
the signals processed by the first and second filters, and 22a6 is a fourth addition for obtaining a
difference signal between the signals processed by the first and second filters The third and
fourth adder outputs are output from the speakers 3L and 3R as a pair of filtered left and right
rear surround signals.
[0025]
Here, when equations (1.1) and (1.2) are modified, X ′ = [(X−Y) / (S−A)] + Y′Y ′ = [(X + Y) /
(S + A)] − X 'is represented by X', and solving for the output signals X 'and Y' results in X '= N (XY) + P (X + Y) Y' = P (X + Y) -N (X-Y), and It can be shown that the filter coefficients P, N can be
given by P = 1 / (S + A) (3.1) N = 1 / (S−A) (3.2). Also, the output signals X 'and Y' are X '= [2
(SX-AY)] / (S2-A2) (4.1) Y' = [2 (SY-AX)] / (S2-A2) It becomes (4.2), and the same result as (1.1)
and (1.2) formulas of the first embodiment is obtained. However, since it has a double value, it
has 6 dB of gain.
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[0026]
Here, the molecule of the formulas (3.1) and (3.2) is expressed by P = (F + K) / (S + A) (5.1) S =
(F−K) / (S−A) (5.2) X '= [2 (SFX + SKY-AFY-AKX)] / (S2-A2) (6.1) Y' = [2 (SFY + SKX-AFX-AKY)] /
(S2-A2) (6.2)
[0027]
This has the same effect as the equations (2.1) and (2.2) when the inputs X = x and Y = 0.
On the other hand, in the input where X = 0 and Y = y, X '= Hr.y (7.1) Y' = Hl.y (7.2). This
indicates that when y is input, the sound image is localized at symmetrical positions with respect
to the position of the sound image input to x. When the signals are input to x and y, respectively,
the superposition rule holds. The sound images are localized at symmetrical positions.
[0028]
Therefore, according to the second embodiment, in the same manner as the first embodiment, in
reproducing video and audio by switching the changeover switch 22d, a multi-channel audio
signal, that is, a 2-channel stereo signal or an 5-channel AC- It is easy to obtain compatibility with
playback of 3 channels in 3 channels or playback in 5 channels, and even when no rear speakers
are prepared, a shuffler as sound image localization circuit 22a of rear surround signals SL, SR
The listener is processed as shown in FIG. 3 (B) by performing processing to localize the sound
image to the left and right of the listener using a filter and adding it to the front two-channel
stereo signals L and R. You can enjoy the moving sound surrounded by the 5ch sound image
while watching the television receiver TV in front, it is easy to restore the original sound field
The things. In particular, since the rear surround signals SL and SR are separate signals, a high
sense of reality can be obtained, and the number of filters used can be reduced to two halves of
that in the first embodiment shown in FIG. 1 to simplify the configuration. It will also be possible
to reduce the cost and incorporate it into a consumer television receiver.
[0029]
Although the AC-3 method developed by Dolby Laboratories is used as an example of the 5-ch
audio signal in the description of each embodiment described above, the present invention is not
limited to this, and the surround signal is L, It includes all signal formats divided into 2 channels
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of R.
[0030]
As described above, according to the video and audio reproduction apparatus according to the
present invention, the multi-channel audio signal of the video and audio including the pair of left
and right rear surround signals is located at the front position substantially symmetrical with
respect to the listener. In a pair of speakers arranged and a video and audio reproduction
apparatus adapted to reproduce from a speaker arranged at the center of the speakers, a
demodulator for demodulating and separating the multi-channel audio signal, and a pair of left
and right separated by the demodulator. Sound image localization means having a convolver
having a filter coefficient set based on a head related transfer function for each channel of a rear
surround signal, and performing filter processing so as to localize a sound image to a rear
position substantially symmetrical with respect to a listener The two channel stereo signals
demodulated and separated by the demodulator are added to generate a center channel signal
component A first adder, an attenuator for attenuating the output level of the first adder, a pair
of left and right rear surround signals through the sound image localization means to the pair of
left and right front stereo signals demodulated and separated by the demodulator And the second
and third adders that supply the output obtained by adding each to the pair of speakers disposed
at the front position substantially symmetrical with respect to the listener, and the output of the
attenuator is selected during stereo reproduction and AC-3 Since the center channel signal
demodulated and separated by the demodulator at the time of reproduction is selected and signal
processing means having a changeover switch for supplying to the speaker arranged at the
center is provided, it is possible to reproduce the video and audio. It is compatible and can be
shared for playback on 3 channels of audio signal or playback on 5 channels, and a rear speaker
is not prepared. There is an effect that can restore the original sound field also.
[0031]
In the sound image localization means, the filter coefficients Hl and Hr are Hl = (SF-AK) / (S2-A2)
Hr = (SK-AF) / (S2-A2) (where S is received from a pair of speakers) Transfer function to the same
side ear of the listener, A is transfer function from a pair of speakers to the opposite ear of the
listener, F is transfer function from the position where the sound image is to be localized to the
same side ear of the listener K is provided with a pair of sound image localization filters set for
transfer functions from the position where the sound image is to be localized to the opposite ear
of the listener) for each channel of the pair of left and right rear surround signals, each channel
The filter output with the filter coefficient set to Hl and the filter output with the different filter
coefficients Hr of the other channels are added each time, and the pair of added outputs is
subjected to the filter processing for the left and right rear pairs Since the signal is output as a
surround signal, the sound at the rear is reproduced by the pair of left and right rear surround
signals arranged in front of the listener by the simple configuration and the speakers disposed at
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the center of the speakers. There is an effect that the expression and movement of the place
become clear and can be applied to consumer equipment such as a television receiver.
[0032]
Furthermore, the sound image localization means includes a first adder for obtaining a sum
signal of the pair of left and right rear surround signals, a second adder for obtaining a difference
signal of the pair of left and right rear surround signals, and a filter coefficient P P = (F + K) / (S +
A) (where S is the transfer function from the pair of speakers to the same side of the listener, A is
the transfer function from the pair of speakers to the other side of the listener, F is The transfer
function from the position where the sound image is to be localized to the same ear of the
listener, K is set to the transfer function from the position where the sound image is to be
localized to the opposite ear of the listener, A second filter processing the output of the second
adder, the first filter processing the output of the second filter, the filter coefficient N being set to
N = (F−K) / (S−A), and Obtaining a sum signal of the signals processed by the first and second
filters , And a fourth adder for obtaining a difference signal of the signals processed by the first
and second filters, wherein the third and fourth outputs are filtered to be a pair of left and right
rear surround Since the signal is output as a signal, the number of filters can be halved as
compared with the case where each pair of left and right rear surround signals is provided with a
pair of sound image localization filters, the configuration is simplified and the cost is reduced for
consumer use The present invention is advantageous in that it can be easily incorporated into a
television receiver.
[0033]
Brief description of the drawings
[0034]
1 is a block diagram showing a first embodiment of the DVD reproduction apparatus of the
present invention.
[0035]
2 is a block diagram of a filter (ATAL-SCHROEDER type filter) used as a sound image localization
circuit of the rear surround signals SL and SR of FIG.
[0036]
3 is an explanatory view for explaining the effect of the video and audio reproduction apparatus
as the first and second embodiments of the signal processing apparatus of the present invention.
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[0037]
4 is a block diagram showing a second embodiment of the DVD reproducing apparatus of the
present invention.
[0038]
5 is a block diagram of a filter (shuffler filter) used as a sound image localization circuit of the
rear surround signals SL, SR in FIG.
[0039]
6 is a block diagram of a sound image localization circuit including the ATAL-SCHROEDER type
filter of FIG. 2 as a component of the sound image localization filter.
[0040]
Explanation of sign
[0041]
1 AC-3 / 2CH Demodulator 2 Signal Processing Means 21a, 21d Left Sound Image Localization
Filter (Sound Image Localization Means) 21b, 21c Right Sound Image Localization Filter (Sound
Image Localization Means) 21e, 21h, 21i Adder 21f Attenuator 21g Switching Switch 22a
Shuffler filter (sound image localization circuit) 22b, 22e, 22f Adder 22c Attenuator 22d
Switching switch 22a1 First adder 22a2 Second adder 22a3 First filter 22a4 Second filter 22a5
Third adder 22a6 Fourth Adder 3L, 3R, 3C Speaker
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