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JPH08265899

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JPH08265899
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
surround reproduction for reproducing multi-channel audio signals, and in particular, it is
possible to easily reproduce multi-channel audio with a two-channel stereo speaker such as a
television receiver in general homes etc. The present invention relates to a surround signal
processing apparatus and an audio / video reproduction apparatus for
[0002]
2. Description of the Related Art As a system for reproducing multi-channel audio signals, there
are the 3-1 system (left front Lch, right Rch, center Cch, surround Sch) in HDTV, and 4ch matrix
system with Dolby Surround. In particular, many U.S. movies have surround tracks with Dolby
Surround sound processing, and in movie theaters are demodulated and played back by multiple
speakers. When this is created as video software, audio that has been subjected to surround
processing as it is is commercially available. As a result, videotape software and laser disks that
have been subjected to many Dolby Surround processing are being sold.
[0003]
However, this system has the following problems. 1) Since the back sound is monaural, the
feeling of movement back and forth can not be expressed completely. 2) Dolby Surround can not
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be completely demodulated because it is an analog matrix system. 3) In order to avoid crosstalk
before and after, the band of surround Sch is limited to 100-7 KHz.
[0004]
To cope with these problems, a method of complete 5 ch configuration as a backward sound has
also been proposed by Dolby Laboratories under the name of AC-3. In this method, 5-channel
signals of 2-channel stereo signals L and R, 1-channel center channel signal C, and 2-channel rear
surround signals SL and SR are compressed and transmitted. Tracks can be diverted and
recorded. In particular, since the 5ch discreet is highly reproducible of the sound field, it can
reproduce the sound field closer to the theater than previous video software.
[0005]
On the other hand, with respect to the system of the rear 1ch such as the Dolby surround up to
now, the rear sound is the listener using the sound image localization technology as in Japanese
Patent Application No. 6-197356 which has already been proposed by the present inventors, for
example. There is a method of creating a signal for localizing the sound image of the surround
sound to the rear, adding this to the front two-channel stereo signals L and R, and reproducing
with the front two-channel speaker. In this case, since the rear sound is a monaural signal, when
the same signal is reproduced by the speaker, a sound image is easily formed in the head and the
surround feeling is impaired. Therefore, a pseudo stereo 2ch signal with reduced correlation is
generated. It must be processed.
[0006]
The present invention has been made in view of the above-mentioned point, and it is possible to
reproduce all channels by a pair of speakers disposed at a front position substantially
symmetrical with respect to the listener in correspondence to the coming 5ch chase. It is an
object of the present invention to obtain a surround signal processing apparatus and an audio /
video reproduction apparatus which can be performed.
[0007]
SUMMARY OF THE INVENTION A surround signal processing apparatus and an audio / video
processing apparatus according to the present invention have a multi-channel audio signal
including a pair of left and right rear surround signals at a front position substantially
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symmetrical with respect to a listener. Sound image localization means described later
comprising a convolver in which a filter coefficient based on a head related transfer function is
set for each channel of the left and right pair of rear surround signals in a surround signal
processing apparatus for reproducing from a pair of arranged speakers The left and right
surround signals are added by adding the left and right pair of rear surround signals through the
sound image localization means to the left and right pair of front stereo signals and localizing the
sound image in the rear position substantially symmetrical with the listener. Reproduction is
performed only with a pair of speakers arranged in the front position, and additional speakers
and amplifiers It is possible to obtain a surround sound system with a moving sense of an
ordinary home television receiver or the like without the hassle of such, make it possible to enjoy
the video software voice processing of 5ch discrete has been made.
[0008]
As one aspect of such sound image localization means, the filter coefficients Hl and Hr are Hl =
(SF-AK) / (S2-A2) Hr = (SK-AF) / (S2-A2) (where S is a pair of speakers) Transfer function from
the listener to the same side of the listener, A is transfer function from the pair of speakers to the
opposite ear of the listener, F is transfer from the position where the sound image is to be
localized to the same side of the listener A function, K is provided with a pair of sound image
localization filters set in the transfer function 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. The filter output with the filter coefficient set to Hl for each channel and the
filter output with the different filter coefficients Hr of the other channels are respectively added,
and the pair of added outputs are subjected to filter processing on the left It is possible to use
one that outputs as a right pair of rear surround signals, and to reproduce the sound field at the
rear for reproducing a pair of left and right rear surround signals by a pair of speakers arranged
in front of the listener by a simple configuration. The movement of the sound image becomes
clearer and can be applied to consumer equipment such as a television receiver.
[0009]
Further, as another aspect of the sound image localization means, a first adder for obtaining a
sum signal of the pair of left and right rear surround signals, and a second adder for obtaining a
difference signal of the pair of left and right rear surround signals; The filter coefficient P is P =
(F + K) / (S + A) (where S is a transfer function from a pair of speakers to the same ear of the
listener, A is a transfer from the pair of speakers to the opposite ear of the listener) Function F is
set as a transfer function from the position where the sound image is to be localized to the same
ear of the listener, K is set as a transfer function from the position where the sound image is
desired to be localized to the opposite ear of the listener A first filter for processing the output of
one adder, and a second filter for processing the output of the second adder, with the filter
coefficient N set to N = (F−K) / (S−A) A filter and a signal processed by the first and second
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filters A third adder for obtaining a signal, 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. By using a pair of left and right rear surround signals for output, the number of filters
can be reduced to half as compared with the case where a pair of sound image localization filters
are provided for each channel of the left and right rear surround signals, thus simplifying the
configuration and cost. Can be easily incorporated into a consumer television receiver.
[0010]
Furthermore, an attenuator for attenuating the center channel signal on the front side of the
multi-channel audio signal is provided, and the output of this attenuator is added to a pair of left
and right front stereo signals and output, thereby a front television receiver Surrounded by a
five-channel sound image of a pair of rear surround signals, a center channel signal, and a pair of
stereo signals on the front while watching, it is possible to enjoy the moving sound and to obtain
high presence.
[0011]
DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> FIG. 1 is a block
diagram showing a first embodiment of a surround signal processing apparatus according to the
present invention.
In FIG. 1, 1 is a demodulator corresponding to the Dolby Labs AC-3 system, which is a digital
signal stream, 2-channel stereo signal L, R, 1-channel center channel signal C, and 2-channel rear
surround signal It demodulates and separates the signal of 5 ch of SL and SR 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.
[0012]
Further, 2 is a display means for displaying an image arranged at a symmetrical position in front
of the listener on the signal of 5ch demodulated and separated by the demodulator 1. For
example, a 2-channel stereo speaker 3L of a television receiver TV A signal processing means for
reproducing from 3R is shown, and the signal processing means 2 is a left side having a pair of
convolvers in which coefficients based on the head related transfer function are set for each
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channel of the rear surround signals SL and SR. And right sound image localization filters 21a
and 21b, and similar right and left sound image localization filters 21c and 21d, and an
attenuator 21e for attenuating the level of the center channel signal C by 3 dB, and a center
channel signal attenuated via the attenuator 21e. Adders 21f and 21g for adding C to a twochannel stereo signal L, R, an adder 21 The adder 21h adds 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 output signal of the left sound image; similarly, the output signal of the right sound image
localization filter 21b and the left sound image localization An adder 21i for adding the output
signal of the filter 21d is provided.
[0013]
Here, as shown in FIG. 2, as a pair of sound image localization filters 21a, 21b, 21d and 21c on
the left and right sides provided for each channel of the rear surround signals SL and SR, the
space characteristic from the speaker is cancelled. Processing is performed so as to localize the
sound image on the left and right sides of the listener using respective ATAL-SCHROEDER type
filters, and is added to the front two-channel stereo signals L and R, respectively.
Here, the ATAL-SCHROEDER type filter will be described.
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.
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 ATAL-SCHROEDER 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.
[0014]
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The output signals X 'and Y' from the loudspeakers LF and RF are X '= (SX-AY) / (S2-A2) Y' = (SYAX) / (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)] with an input of X = Fx, Y = Kx. X = Hr · x, and
sound image localization is realized. The filter has these Hl and Hr as coefficients.
[0015]
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 both ears 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.
[0016]
[Equation 2] The outputs x and y of the two ears by the speakers 3L and 3R arranged at the front
left and right symmetrical positions are shown by x = SX '+ AY'y = AX' + SY ', and this output is a
cancellation filter Since we want to be equal to the inputs X, Y, we can replace x, y with the
inputs X, Y and express X = SX '+ AY'Y = AX' + SY ', so based on this equation, For the inputs X
and Y, the outputs X 'and Y' from the speaker are X '= (SX-AY) / (S2-A2) (1.1) Y' = (SY-AX) / (S2A2) ) (1.2)
[0017]
Next, consider the convolution of the transfer function in the direction to be localized.
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In FIG. 2, when the signal x is reproduced from the speaker (position Xp) on the left side behind
the listener, signals Fx and Kx in which transfer functions F and K are convoluted in the left ear Lear and the right ear R-ear of the listener respectively It becomes. If this signal is applied to the
above inputs X and Y, sound image localization can be realized.
[0018]
That is, if X = Fx and Y = Kx in FIG. 2 and the equation (1.2) is input, X '= [(SF-AK) / (S2-A2)]. X =
Hl.x (2.1) Y '= [(SK-AF) / (S2-A2)] x = Hrx (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.
[0019]
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).
[0020]
With the above configuration, among the 5ch signals demodulated and separated from the
demodulator 1 shown in FIG. 1, the two-channel stereo signals L and R are arranged at
approximately forward symmetrical positions relative to the listener via the adders 21f to 21i.
And the center channel signal C is distributed to the speakers 3L and 3R via the adders 21f to
21i after being dropped by 3 dB in level via the attenuator 21e. Also, the rear surround signals
SL and SR are transmitted to the listener via a pair of left and right sound image localization
filters 21a and 21b using ATAL-SCHROEDER type filters as shown in FIG. 2 and 21c and 21d,
respectively. Processing is performed to localize the sound image to the left and right, and the
front 2 channels via the adders 21h and 21i Stereo signals L, by being added to the R, the
listener can enjoy the moving sound surrounded by the sound image of the 5ch while watching
in front of the TV.
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In particular, since the rear surround signals SL and SR are separate signals, a high sense of
reality can be obtained.
[0021]
That is, as shown in FIG. 3A, the rear surround signals SL and SR are reproduced from the
position as shown in FIG. 3B simply by providing the pair of speakers 3L and 3R on both sides of
the television receiver TV. It is possible to reproduce three-dimensional surround sound by a
stereo signal from the front and a rear stereo signal (rear surround) localized to the rear, without
setting a rear speaker.
[0022]
Second Embodiment FIG. 4 is a block diagram showing a second embodiment of the surround
signal processing 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, the 5-channel signal demodulated and
separated by the demodulator 1 is disposed at a symmetrical position in front of the listener, for
example, a 2-channel stereo speaker 3L of the television receiver TV. , 3R as a signal processing
means 2 for processing the rear surround signals SL, SR so that sound images are localized
behind the listener and sound image localization for reproduction from the front two-channel
stereo speakers 3L, 3R Circuit 22a, Attenuator 22b for attenuating the level of center channel
signal C by 3 dB, Adders 22c and 22d for adding center channel signal C attenuated via
attenuator 22b to 2-channel stereo signals L and R, addition Channel of the rear surround signal
through the sound image localization circuit 22a to the signal through the No. adder 22e,
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likewise for adding, an adder 22f for adding the R channel signal of the rear surround signal
through the sound image localization circuit 22a to signal via the adder 22d.
[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
inventors 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 And outputs the
third and fourth outputs 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 'and solving for the output signals X' and Y 'results in X' = N (X-Y) + P (X + Y) Y '= P (X
+ Y) -N (X-Y), It is shown that a shuffler filter can be constructed, and the filter coefficients P, N
are given by P = 1 / (S + A) (3.1) N = 1 / (S−A) (3.2). Further, 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.
[0026]
Where P = (F + K) / (S + A) and (5.1) S = (F−K) / (S−A) (3) 5.2) X '= [2 (SFX + SKY-AFY-AKX)] /
(S2-A2) (6.1) Y' = [2 (SFY + SKX-AFX-AKY)] / (S2-A2) (6. 2)
[0027]
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## EQU6 ## When the inputs X = x and Y = 0, the same result as the equations (2.1) and (2.2) is
obtained.
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 above embodiment, a shuffle filter is used as the sound image
localization circuit 22a of the rear surround signals SL and SR, and processing is performed to
localize the sound image on the left side and the right side of the listener. By adding to R, as
shown in FIG. 3 (B), the listener can enjoy the moving sound surrounded by the sound image of
5ch while looking at the front television receiver TV, as shown in FIG. 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 system 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 surround signals are L and R. Includes all signal formats divided into 2
channels.
[0030]
As described above, according to the surround signal processing apparatus and the video / audio
processing apparatus according to the present invention, a multichannel audio signal including a
pair of left and right rear surround signals is substantially symmetrical in front of the listener on
the front side. A predetermined sound image having a convolver in which a filter coefficient
based on a head related transfer function is set for each channel of the pair of left and right rear
surround signals in a surround signal processing apparatus configured to reproduce from a pair
of speakers arranged at a position A pair of left and right surround surround signals are provided
by including localization means, adding the pair of left and right rear surround signals through
the sound image localization means to the pair of left and right front stereo signals and
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rearranging the sound image in the rear position substantially symmetrical to the listener. The
signal is reproduced only by the pair of speakers placed in the front position, and the speaker
and amplifier are added, It is possible to obtain a surround sound system with a moving sense of
an ordinary home television receiver or the like without the hassle such as wiring, there is an
effect that it is possible to enjoy the video software voice processing of 5ch discrete has been
made.
[0031]
That is, as the predetermined sound image localization means, the filter coefficients Hl and Hr are
Hl = (SF-AK) / (S2-A2) Hr = (SK-AF) / (S2-A2) (where S is a pair of speakers) Transfer function
from the listener to the same side ear, 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 in the transfer function 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, The filter output in which the filter coefficient is set to Hl for each channel and
the filter output in which different filter coefficients Hr of other channels are set are respectively
added, and the pair of added outputs is subjected to filter processing on the left By using the one
output as the right pair of rear surround signals, it is possible to reproduce the sound field
expression and the sound image at the rear to reproduce the left and right pair of rear surround
signals by the pair of speakers arranged in front of the listener by a simple configuration. The
effect is that the movement of the camera can be made clearer and can be applied to consumer
equipment such as a television receiver.
[0032]
Further, as the sound image localization means, 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 Obtain 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, and
the left and right pairs of the third and fourth outputs are filtered. By using a signal to be output
as a surround signal, the number of filters can be halved as compared to the case where a pair of
sound image localization filters are provided for each channel of a pair of left and right rear
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surround signals, thereby simplifying the configuration and reducing cost. There is an effect that
it can be easily incorporated into a consumer television receiver.
[0033]
Furthermore, an attenuator for attenuating the center channel signal on the front side of the
multi-channel audio signal is provided, and the output of this attenuator is added to a pair of left
and right front stereo signals and output, thereby a front television receiver Surrounded by a 5channel sound image of a pair of rear surround signals, a center channel signal, and a pair of
stereo signals on the front while watching, there is an effect that it is possible to enjoy the
moving sound and obtain a high sense of reality .
[0034]
Brief description of the drawings
[0035]
1 is a block diagram showing a first embodiment of the surround signal processing apparatus of
the present invention.
[0036]
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.
[0037]
3 is an explanatory view for explaining the effect of the video and audio reproduction apparatus
as the first and second embodiments of the surround signal processing apparatus of the present
invention.
[0038]
4 is a block diagram showing a second embodiment of the surround signal processing apparatus
of the present invention.
[0039]
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.
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[0040]
6 is a block diagram of a sound image localization circuit including an ATAL-SCHROEDER filter as
a component of the ATAL-SCHROEDER type filter of FIG.
[0041]
Explanation of sign
[0042]
Reference Signs List 1 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 attenuator 21f to 21i adder 22a shuffler filter (sound
image localization circuit) 22b attenuation 22c to 22f Adder 22a1 First Adder 22a2 Second
Adder 22a3 First Filter 22a4 Second Filter 22a5 Third Adder 22a6 Fourth Adder 3L, 3R Speaker
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