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JP2009071406

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DESCRIPTION JP2009071406
An object of the present invention is to provide a wavefront synthesis signal conversion device
that calculates a wavefront synthesis reproduction signal according to a reproduction device to
be actually used from the assumed number of speakers and specifications of speaker intervals,
and reproduces a synthesis sound field. A wavefront synthesis reproduction condition
information input unit for inputting wavefront synthesis reproduction condition information
which is a reproduction condition of a wavefront synthesis reproduction signal including at least
reproduction speaker arrangement information, and a wavefront synthesis reproduction signal
for inputting wavefront synthesis reproduction signals of a plurality of channels. Using a
reproduction signal input unit and a reproduction speaker position of each channel obtained
from wavefront synthesis reproduction condition information as a primary sound source position
of wavefront synthesis, a new wavefront synthesis speaker having a speaker arrangement of each
channel different from the wavefront synthesis reproduction condition And a wavefront synthesis
signal conversion unit for converting the signal into a wavefront synthesis reproduction signal.
[Selected figure] Figure 8
Wavefront synthetic signal conversion apparatus and wavefront synthetic signal conversion
method
[0001]
The present invention relates to a wavefront synthesis signal conversion device and a wavefront
synthesis signal conversion method.
[0002]
04-05-2019
1
A stereo reproduction system is widely known which reproduces multi-channel audio signals
using a plurality of speakers in order to reproduce realistic sounds.
For example, a 5.1 channel surround system uses five speakers and one subwoofer speaker to
play sound. Arrange the speakers according to the provisions of ITU-R BS 775 (International
Telecommunication Union Radiocommunications Sector), and different sound waves are output
from the speakers corresponding to each channel, and the listener hears the listener, making the
listener feel more realistic You can enjoy some sounds.
[0003]
A stereo reproduction system such as a 5.1 channel surround system can obtain a target sound
image localization at a predetermined listening position. However, since such a stereo
reproduction system has a narrow range in which the target sound image localization can be
obtained, the reproduction sound heard by the listener is heard at the predetermined listening
position at a place other than the predetermined listening position. Compared to the playback
sound.
[0004]
Therefore, there is a multi-channel audio system that aims to physically reproduce in space the
sound field itself in which the original sound source existed. A multi-channel audio system
records wavefronts generated by a sound source in an original sound field, and reproduces the
wavefront in a space different from the current sound field based on the recorded wavefronts.
The multi-channel audio system uses wavefront synthesis technology, which is a sound synthesis
technology, and sound waves are output from an array speaker consisting of a plurality of
speakers. The outputted sound waves are transmitted to the listener as waves without
interference. By hearing the sound wave, the listener can enjoy a realistic sound.
[0005]
In order to reproduce the wavefront in a wide band, it is necessary to narrow the microphone
interval of the microphone array for recording the wavefront and the speaker interval of the
04-05-2019
2
array speaker for reproducing the wavefront to several centimeters or less. The speaker spacing
can be expanded to some extent by the technique disclosed in Patent Document 1. In addition, in
the case of reproducing a sound such as a reflected sound coming from the back of the listener, it
is necessary to arrange an array speaker for reproduction so as to surround the listening area of
the listener. With this technology, it is possible to reproduce the sound coming from the back of
the listener only with the array speaker arranged in front of the listener.
[0006]
In a multi-channel audio system using wavefront synthesis technology, without performing
wavefront information recording in the actual sound field, the musical instrument performance is
performed with the sound source serving as the current sound field and the room in which it is
present as fictional. , Etc., can be arranged as a virtual sound source in an imaginary room to
perform wavefront synthesis. By performing wavefront synthesis in this way, it is possible to
reproduce the sound field that these sources would produce in a real room.
[0007]
For example, Patent Document 3 discloses a technique for performing wave field synthesis in a
pseudo manner even in the case of the speaker arrangement of the 5.1 channel surround system.
The technique disclosed in Patent Document 3 reproduces the sound field by spatial harmonics
that substantially exactly match spatial harmonics of the original sound field through multiple
loudspeakers. It is a method of recording or transmitting a sound field from a signal. In this
technique, to preserve spatial harmonics, the monophonic sound source is processed by
mastering such that all speaker channels contribute to sound synthesis. And, if the speaker
configuration is different from the one assumed at the time of mastering, the speaker signal is a
space harmonic of the sound field reproduced by the different speaker configuration is a space
harmonic of the original sound field It is reprocessed at a playback location (such as home) to
coincide with the waves. By reprocessing in this way, it is possible to reproduce the original
sound field that performs wave field synthesis in a pseudo manner.
[0008]
JP-A-2005-80079 JP-A-2007-184818 JP-A-2003-531555
[0009]
04-05-2019
3
However, in a 5.1 channel surround system, as defined in ITU-R BS 775, the listener needs to
hear the sound in the center of the juxtaposed speakers.
Therefore, there is a problem that it is not possible to reproduce a realistic sound for other
listeners who listen at places other than the center. In addition, the 5.1 channel surround system
does not physically reproduce the sound field itself where the original sound source was present,
and uses the auditory psychology of the listener so that there is realism when listening with both
ears. Aim to make them Therefore, depending on the listener, there was a problem that the effect
was different.
[0010]
Further, in the case of reproduction by wavefront synthesis technology, it is necessary to perform
signal processing of sound recording and wavefront synthesis in accordance with the speaker
spacing, arrangement, and configuration of an array speaker that outputs sound. As a result,
multi-channel signals created for a particular loudspeaker spacing, placement and configuration
may not be reproduced as expected in multi-channel audio systems with other loudspeaker
spacing, placement and configuration.
[0011]
In the technique of Patent Document 3 for performing wave field synthesis in a pseudo manner
in a 5.1 channel surround system, mathematically, the spatial impulse representing the sound
source position is accurately represented by a large number of orders, but in the case of this
system It is assumed that only one speaker is used. Therefore, there is a limit to the number of
spatial harmonics that can be included in the reproduced sound field, and the system of
wavefront synthesis becomes very bad. Therefore, although there is some improvement in
direction perception and sense of presence with respect to the direction in which the sound
arrives from the conventional 5.1 channel surround system, it is as if the musical instrument is
sounding near or far from the listener in the original sound field. It was also difficult to get a
sense of presence, and to make the listener who listens at places other than the center experience
a sense of reality.
04-05-2019
4
[0012]
If the sound source position, the sound source signal, and the information (number of speakers
and the speaker interval) of the assumed listening area are known, according to the specification
of the reproduction system, for example, the signal processing capability, the number of speakers
and the speaker interval, There has also been proposed a technology for converting a sound
source position and a sound source signal to create a wavefront synthesis reproduction signal.
However, in the case of this technology, the wavefront synthesis reproduction signal for
reproduction can not be calculated unless the sound source position, the sound source signal,
and the information (the number of speakers and the speaker interval) of the assumed listening
area are all known in advance. there were.
[0013]
Therefore, the present invention has been made in view of the above problems, and an object of
the present invention is to produce a wavefront synthesis content, for example, when
reproducing a realistic sound field using a wavefront synthesis technique. New and improved
wavefront that can be used to calculate the wave field synthesis reproduction signal according to
the reproduction device to be actually used from the specifications of the number of speakers
and the speaker interval assumed at the time of An object of the present invention is to provide a
synthesized signal conversion device and a wavefront synthesized signal conversion method.
[0014]
According to an aspect of the present invention, there is provided a wavefront synthesis signal
conversion apparatus for converting a wavefront synthesis reproduction signal for which a
wavefront synthesis reproduction condition is specified to be suitable for different wavefront
synthesis reproduction conditions. A wavefront synthesis reproduction condition information
input unit for inputting wavefront synthesis reproduction condition information that is a
reproduction condition of a wavefront synthesis reproduction signal including at least
reproduction speaker arrangement information, and a wavefront synthesis reproduction signal
input for inputting wavefront synthesis reproduction signals of a plurality of channels And the
wave front synthesis reproduction signal input from the wave front synthesis reproduction signal
input unit with the reproduction speaker position of each channel obtained from the wave front
synthesis reproduction condition information as the primary sound source position of the wave
front synthesis different from the wave front synthesis reproduction condition A wavefront
synthesis reproduction signal conversion unit for converting a wavefront synthesis reproduction
signal for a new wavefront synthesis speaker having a speaker arrangement of each channel;
Wherein, wave field synthesis signal converter is provided.
04-05-2019
5
[0015]
According to this configuration, the wavefront synthesis reproduction condition information
input unit inputs wavefront synthesis reproduction condition information which is a reproduction
condition of the wavefront synthesis reproduction signal including at least the reproduction
speaker arrangement information, and the wavefront synthesis reproduction signal input unit
includes the plurality of channels. The wavefront synthesis reproduction signal is input, and the
wavefront synthesis reproduction signal conversion unit receives the reproduction speaker
position of each channel obtained from the wavefront synthesis reproduction condition
information as the primary sound source position of wavefront synthesis from the wavefront
synthesis reproduction signal input unit. The wavefront synthesis reproduction signal is
converted into a wavefront synthesis reproduction signal for a new wavefront synthesis speaker
having a speaker arrangement of each channel different from the wavefront synthesis
reproduction condition.
As a result, even when reproduction is performed with a speaker having a specification different
from that of the wave-field synthesis reproduction condition designated as the wave-field
synthesis reproduction signal, it is possible to reproduce a predetermined reproduction sound
field without recreating the wave-field synthesis signal.
[0016]
The new wavefront synthesis speaker is a linear array speaker, and the wavefront synthesis
reproduction signal conversion unit reproduces the wavefront from the primary sound source
position with a new wavefront synthesis speaker having a speaker arrangement of each channel
different from the wavefront synthesis reproduction condition. The wavefront synthesis filter
coefficients to be calculated are calculated, and filtering is performed on wavefront synthetic
reproduction signals of a plurality of channels input from the wavefront synthetic reproduction
signal input unit.
As a result, even if reproduction is performed with a speaker having a specification different from
that of the wave-field synthesis reproduction condition designated for the wave-field synthesis
reproduction signal, the predetermined reproduction sound field can be reproduced. Can be
reproduced.
04-05-2019
6
[0017]
The wavefront synthesis reproduction condition information input unit inputs the number of
speaker channels and the speaker interval as reproduction information of wavefront synthesis
reproduction signals of a plurality of channels to be input. As a result, it is possible to synthesize
a desired sound field even if the number of speaker channels as reproduction information of
wavefront synthesis reproduction signals of a plurality of input channels is different from the
speaker interval.
[0018]
The wavefront synthesis reproduction signal conversion unit separates frequency components
exceeding the wavefront synthesis upper limit frequency in the speaker arrangement of the new
wavefront synthesis speaker from the wavefront synthesis reproduction signals of the plurality of
channels input by the wavefront synthesis reproduction signal input unit. , A high frequency
component channel assignment unit for assigning the wave-field synthesized signal component
separated by the high frequency band separation unit to a channel of a new wave-field synthesis
speaker, and each channel converted by the wave-field synthesis reproduction signal conversion
unit And a signal mixing unit for mixing the wave-field synthesis reproduction signal and the
high frequency component signal assigned to each channel by the high frequency component
channel assignment unit. As a result, a signal including a frequency component higher than the
upper limit frequency at which wavefront synthesis is possible can be added so as not to disturb
sound image perception in the wavefront synthesis frequency band, so that a more natural tone
can be reproduced.
[0019]
In order to solve the above problems, according to another aspect of the present invention, there
is provided a wavefront synthesis and reproduction apparatus for reproducing a wave front
synthesis reproduction signal for which a wave front synthesis synthesis condition is specified, at
least reproduction speaker arrangement information A wavefront synthesis reproduction signal
input unit for inputting the reproduction condition information of the wavefront synthesis
reproduction signal including the wavefront synthesis reproduction signal of the plurality of
channels, and each channel obtained from the wavefront synthesis reproduction condition
information And a wavefront synthesis reproduction signal conversion unit for converting the
reproduction speaker position of the first wave source into a wave front synthesis reproduction
signal for a new wave field synthesis speaker having a speaker arrangement of each channel
04-05-2019
7
different from the wave field synthesis reproduction condition. A wavefront synthesis speaker for
converting the signal converted by the wavefront synthesis reproduction signal conversion unit
into an acoustic signal and outputting the acoustic signal; and a plurality of channels obtained by
the wavefront synthesis reproduction signal input unit The wavefront synthesis reproduction
control unit controls reproduction of the wavefront synthesis reproduction signal of the speaker,
and the wavefront synthesis reproduction control unit is a speaker among the reproduction
condition information of the wavefront synthesis reproduction signal obtained by the wavefront
synthesis reproduction condition information input unit. When the number of channels and the
speaker spacing do not match the number of speaker channels and the speaker spacing of the
wavefront synthesis speaker, the wavefront synthesis reproduction signal of the plurality of
channels obtained by the wavefront synthesis reproduction signal input unit is processed by the
wavefront synthesis reproduction signal conversion unit A plurality of channels obtained by the
wavefront synthesis reproduction signal input section are controlled if control is made so as to be
sent to the wavefront synthesis speaker after being recombined so as to be suitable for the
reproduction apparatus and the number of loudspeaker channels of the wavefront synthesis
speaker and the speaker spacing match. Control to send to the wavefront synthesis speaker
without recombining the wavefront synthesis reproduction signal of the Apparatus is provided.
[0020]
According to this configuration, the wavefront synthesis reproduction condition information
input unit inputs reproduction condition information of the wavefront synthesis reproduction
signal including at least reproduction speaker arrangement information, and the wavefront
synthesis reproduction signal input unit inputs wavefront synthesis reproduction signals of a
plurality of channels. The wave front synthesis reproduction signal conversion unit sets the
reproduction speaker position of each channel obtained from the wave front synthesis
reproduction condition information as a primary sound source position of wave front synthesis,
and has a new speaker arrangement of each channel different from the wave front synthesis
reproduction condition. A wavefront synthesis reproduction signal for a wavefront synthesis
speaker is converted.
Then, the wavefront synthesis reproduction control unit compares the specification of the
wavefront synthesis speaker with the wavefront synthesis reproduction condition information,
and controls the wavefront synthesis reproduction signal to be converted by the wavefront
synthesis reproduction signal conversion unit if the conditions are different. As a result, the
wavefront synthesis reproduction signal can be converted as needed by comparing the
reproduction condition for the wavefront synthesis reproduction signal with the specification of
the wavefront synthesis reproduction apparatus.
04-05-2019
8
[0021]
The wavefront synthesis reproduction signal conversion unit separates frequency components
exceeding the wavefront synthesis upper limit frequency in the speaker arrangement of the new
wavefront synthesis speaker from the wavefront synthesis reproduction signals of the plurality of
channels input by the wavefront synthesis reproduction signal input unit. , A high frequency
component channel assignment unit for assigning the wave-field synthesized signal component
separated by the high frequency band separation unit to a channel of a new wave-field synthesis
speaker, and each channel converted by the wave-field synthesis reproduction signal conversion
unit And a signal mixing unit for mixing the wave-field synthesis reproduction signal and the
high frequency component signal assigned to each channel by the high frequency component
channel assignment unit. As a result, a signal including a frequency component higher than the
upper limit frequency at which wavefront synthesis is possible can be added so as not to disturb
sound image perception in the wavefront synthesis frequency band, so that a more natural tone
can be reproduced.
[0022]
As a result, even if reproduction is performed with a speaker having a specification different from
that of the wave-field synthesis reproduction condition designated as the wave-field synthesis
reproduction signal, a predetermined reproduction sound field can be reproduced, and it is not
necessary to recreate the wave-field synthesis signal.
[0023]
Further, in order to solve the above problems, according to still another aspect of the present
invention, wavefront synthesis signal conversion is performed to convert wavefront synthesis
reproduction signals for which wavefront synthesis reproduction conditions are specified to be
suitable for different wavefront synthesis reproduction conditions. A wavefront synthesis
reproduction condition information input step for inputting wavefront synthesis reproduction
condition information which is a reproduction condition of a wavefront synthesis reproduction
signal including at least reproduction speaker arrangement information, and a wavefront for
inputting wavefront synthesis reproduction signals of a plurality of channels The wavefront
synthesis reproduction signal input in the wavefront synthesis reproduction signal input step is
wavefront synthesis reproduction using the synthesis reproduction signal input step and the
reproduction speaker position of each channel obtained from the wavefront synthesis
reproduction condition information as the primary sound source position of wavefront synthesis.
Wavefront synthesis to be converted to a wave front synthesis reproduction signal for a new
04-05-2019
9
wave front synthesis speaker having a speaker arrangement of each channel different from the
conditions Characterized in that it comprises a raw signal conversion step, the wavefront
synthesis signal conversion method are provided.
[0024]
According to this configuration, the wavefront synthesis reproduction condition information
input step inputs wavefront synthesis reproduction condition information which is a
reproduction condition of the wavefront synthesis reproduction signal including at least
reproduction speaker arrangement information, and the wavefront synthesis reproduction signal
input unit step includes a plurality of channels. The wavefront synthesis reproduction signal is
input, and the wavefront synthesis reproduction signal conversion step is input in the wavefront
synthesis reproduction signal input step with the reproduction speaker position of each channel
obtained from the wavefront synthesis reproduction condition information as the primary sound
source position of wavefront synthesis. The wavefront synthesis reproduction signal is converted
into a wavefront synthesis reproduction signal for a new wavefront synthesis speaker having a
speaker arrangement of each channel different from the wavefront synthesis reproduction
condition.
As a result, even when reproduction is performed with a speaker having a specification different
from that of the wave-field synthesis reproduction condition designated as the wave-field
synthesis reproduction signal, it is possible to reproduce a predetermined reproduction sound
field without recreating the wave-field synthesis signal.
[0025]
As described above, according to the present invention, when reproducing a sound field having a
sense of presence using a wavefront synthesis technique, the specifications of the number of
speakers and the speaker interval assumed when producing the wavefront synthesis content, It is
possible to provide a new and improved wavefront synthesis signal conversion device and a
wavefront synthesis signal conversion method capable of calculating a wavefront synthesis
reproduction signal and reproducing a synthesis sound field according to a reproduction device
actually used. .
[0026]
04-05-2019
10
The present invention will now be described more fully with reference to the accompanying
drawings, in which exemplary embodiments of the invention are shown.
In the present specification and the drawings, components having substantially the same
functional configuration will be assigned the same reference numerals and redundant description
will be omitted.
[0027]
First, wavefront synthesis technology using an array speaker will be described.
In order to reproduce a sound field by wavefront synthesis using an array speaker, a
multichannel reproduction signal (wavefront synthesis reproduction signal) to be supplied to an
array speaker system consisting of a plurality of speaker units is generated, and a multichannel
reproduction signal is generated. Output sound from each speaker unit according to. The sounds
output from the individual speaker units are synthesized in space and reproduced so that sound
waves arrive at the listener from the direction of the desired sound source.
[0028]
That is, the multi-channel reproduction signal is created so that the wave front can be
reproduced when sound is output from the array speaker system. For example, Takeda et al.,
"Study on wave-field synthesis using multi-channel speaker reproduction" A signal created by the
method as described in the conference lecture proceedings, pp. 407-408, September 2000 can
be used as a multi-channel signal. Then, since the wave front coming from the sound source is
reproduced in the listening area, sound image localization to a predetermined position can be
obtained in a wide listening range for the sound image.
[0029]
FIG. 1 is an explanatory diagram for explaining an example of an array speaker for wavefront
synthesis reproduction and a standard listening position assumed by a content producer who
produces video and audio (hereinafter, the video and audio are also generically referred to as
04-05-2019
11
“content”). It is. In FIG. 1, an array speaker with 24 channels and 8 cm intervals is described as
an example as the array speaker 1 for wavefront synthesis reproduction. In addition, the
standard listening position 2 assumed by the content producer is a position 2 m away from the
center of the array speaker 1.
[0030]
The content producer arranges the performance sound of the musical instrument as a primary
sound source and produces content for reproducing a realistic sound field by wavefront
synthesis so as to be suitable for the array speaker 1 as shown in FIG. 1 .
[0031]
Usually, the primary sound source is located inside the line passing through the standard
listening position 2 and the speaker unit at the end of the array speaker 1 and at a distance of 1
m or more from the listener side from the array speaker 1.
For example, in the example illustrated in FIG. 1, the area in which the primary sound source is
disposed is defined as the area inside the dotted line indicated by reference numeral 3 in FIG. 1.
In FIG. 1, the area setting is such that the area where the primary sound source is arranged is
limited also in the depth direction. This is because of the nature of distance perception by human
hearing, the effect of wavefront information on distance perception becomes smaller as it is
separated from a sound source by about 3 to 5 m, and the distance to be approached depends on
the level of incoming sound and the degree of reflection and reverberation. The sound source for
reproducing the sound field by wave field synthesis is placed up to a position 3 to 5 m away from
the standard listening position, and the sound source further than that is a level adjustment,
reflection and reverberation. It is because it can cope with adjustment of addition of.
[0032]
The primary sound source can include, in addition to the sound directly arriving to the listener, a
reflected sound from a virtually provided wall and a reverberant sound as a sound source to be
reproduced by wavefront synthesis. For example, when the sound source a (code 4a) is arranged
as the primary sound source, another sound source a '(code 4a') can be arranged as the sound
source a reflected from the wall behind the stage. In this case, the sound source a 'is a sound
source a to which time delay and reverberation processing are added.
04-05-2019
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[0033]
FIG. 2 is an explanatory diagram for explaining an example of an array speaker different from the
array speaker for wavefront synthesis reproduction (for example, the array speaker 1 shown in
FIG. 1) assumed by the content producer. In FIG. 2, an array speaker with 16 channels and 6 cm
intervals is described as an example as the array speaker 1 a for wavefront synthesis
reproduction.
[0034]
Since the array speaker 1a shown in FIG. 2 is different in configuration from the array speaker 1
assumed by the content producer, it is possible to directly reproduce the content produced
assuming the array speaker and the standard listening position shown in FIG. Can not.
[0035]
FIG. 3 is an explanatory view for explaining another example of the array speaker different from
the array speaker for wavefront synthesis reproduction (for example, the array speaker 1 shown
in FIG. 1) assumed by the content producer.
In FIG. 3, an array speaker with 8 channels and 6 cm intervals is described as an example as the
array speaker 1b for wavefront synthesis reproduction.
[0036]
Similar to the array speaker 1a shown in FIG. 2, the array speaker 1b shown in FIG. 3 is different
in configuration from the array speaker 1 assumed by the content producer, so the array speaker
shown in FIG. 1 and the standard listening position are assumed. It is not possible to play back
the produced content as it is.
[0037]
In this embodiment, in order to reproduce the content produced assuming the array speaker and
the standard listening position shown in FIG. 1 with an array speaker different from those
assumed as shown in FIG. 2 and FIG. A wavefront synthesis signal conversion apparatus and a
04-05-2019
13
wavefront synthesis signal conversion method for reproducing by an array speaker different
from the assumed array speaker by converting a reproduction signal will be described.
[0038]
In order to show the positional relationship between the array speakers 1a and 1b shown in FIGS.
2 and 3 and the array speaker 1 shown in FIG. 1, the array speakers 1 are shown by dotted lines
in FIGS.
By setting such a positional relationship, a sound field is synthesized as if the original array
speaker 1 is present at the standard listening position 2 and a sound by wavefront synthesis is
emitted from the array speaker 1, and content production is performed. Can hear the sound that
comes from the original primary sound source that the person assumed.
[0039]
In such a case, an array speaker that actually uses the sound wave surface emitted from the new
primary sound source position with the position of each speaker channel of the original array
speaker 1 for wavefront synthesis as the new primary sound source position. It is reproduced by
synthesizing the sound wave planes from 1a and 1b.
For this purpose, a wavefront synthesis filter that is reproduced by synthesizing the sound wave
planes from the array speakers 1a and 1b is inserted in front of the array speakers 1a and 1b as
a wavefront synthesis reproduction speaker conversion filter.
[0040]
FIG. 4 is an explanatory view for explaining setting of the wavefront synthesis filter according to
the embodiment of the present invention. FIG. 4 illustrates a method of generating a wave-field
synthesis filter for reproducing the sound field as expected from the original primary sound
source assumed by the content creator using the array speaker 1a shown in FIG. . Specifically,
the speaker units u1, u2,..., U24 of each channel of the array speaker 1 are used as primary
sound sources, and wavefronts emitted from the respective speaker units are reproduced using
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the array speaker 1a. Wave front synthesis filters h1.1, h1.2, ..., h1.16, h2.1, h2.2, ..., h2.16, ...,
h24.1, h24.2, ... , H24.16 will be described.
[0041]
The transfer characteristic from the primary sound source, for example u1, to the control point j
in the control area provided on the front of the array speaker 1a is a1. Assuming that j, the
response at the control point j by the primary sound source u1 is u1 · a1. It is represented by j
(see FIG. 4 (a)).
[0042]
On the other hand, the response that the array speaker 1a consisting of 16 speaker units w1,
w2,..., W16 makes at the control point j has a transfer characteristic from the speaker units w1,
w2,. cj. 1, cj. 2, ..., cj. Assuming that u1 · h1.1 · cj. 1 + ... + u1 · h1. k · cj. k + ... + u1 · h1.16 · cj. 16
(see FIG. 4 (b)).
[0043]
The wavefront synthesis filter for the primary sound source u1 is operated such that the
difference between the response of the original sound field (original sound field) and the
response due to wavefront synthesis, ie, the reproduction error, is minimized for all control
points in the control area. Do.
The details are prepared, for example, by the method described in Takeda et al., “Study on
wave-field synthesis using multi-channel speaker reproduction”, as described above, in the
Proceedings of the Acoustical Society of Japan, pp. 407-408, September 2000. be able to.
[0044]
By creating the wavefront synthesis filter in this manner, a sound field is synthesized as if the
original array speaker 1 exists at the standard listening position 2 and the sound by the
wavefront synthesis is emitted from the array speaker 1. You can hear the sound that comes
from the primary sound source originally intended by the producer.
[0045]
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15
The conversion process described above applies only to frequency components lower than the
wavefront synthesis upper limit frequency at which wavefront synthesis can be accurately
performed.
The wavelength at which the wave-field synthesis can be accurately performed is a case where
the speaker unit interval is shorter than a half wavelength, that is, a wavelength longer than
twice the speaker interval.
Therefore, the wavefront synthesis upper limit frequency fh is calculated by fh = {(340/2) /
speaker unit interval} [Hz], assuming that the sound velocity is 340 m / sec.
[0046]
In practice, the angle θ between the sound wave front and the array speaker is also limited to
the upper limit of the θ value if the arrangement range of the primary sound sources is limited
as shown in FIG. Therefore, as shown in FIG. 10, the wave-field synthesis upper limit frequency fh
is increased by 1 / sin θ. That is, since sin θ = 1 when θ is 90 degrees, the wave front
synthesis upper limit frequency fh 90 becomes fh 90 = {(340/2) / speaker unit spacing} [Hz], and
the wave front synthesis upper limit frequency at other angles fh is fh = fh90 × 1 / sin θ [Hz].
[0047]
Therefore, a sound source based on actual wavefront synthesis is often produced so that
frequencies higher than the wavefront synthesis upper limit frequency are also output from the
array speaker.
[0048]
FIG. 5 is an explanatory diagram for explaining an example of the case where the sound of the
frequency component higher than the wave front synthesis upper limit frequency is output from
the array speaker.
In the example shown in FIG. 5, for the high frequency components, the left and right level
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differences are controlled in the same manner as in the intensity stereo, using speaker units
located at both ends of the array speaker 1.
[0049]
Further, even in the case of the array speakers 1a and 1b shown in FIG. 2 and FIG. 3, the level
difference between the left and right may be controlled similarly to the intensity stereo using the
speaker units at both ends. In these cases, the difference between the position of the array
speaker 1 as the standard and the time of the lower part is set so that the wavefront synthesis
frequency band component for wavefront synthesis and the high frequency component
synchronously reach the standard listening position 2. It is desirable to adjust the axis.
[0050]
Strictly speaking, at the listening position apart from the standard listening position 2 assumed,
the time difference between the wave-field synthesis frequency band component and the high
frequency component occurs, but it is important for sound image localization judgment and the
energy is large Since the middle and low frequency components can be accurately generated by
wavefront synthesis and sound image perception can be performed by sound case composition,
the time difference between the wavefront combination frequency band component and the high
frequency components makes the sound image unnatural. There is nothing to do.
[0051]
FIG. 6 is an explanatory diagram for explaining another example in the case of outputting the
sound of the frequency component higher than the wave front synthesis upper limit frequency
from the array speaker.
In the example shown in FIG. 6, for the primary sound source including the high frequency
component, the high frequency component is output from the speaker unit of the array speaker
located in the direction closest to the primary sound source direction viewed from the standard
listening position 2 Is described.
[0052]
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For example, as shown in FIG. 6, when there are primary sound sources A, B, C including high
frequency components, the fifth speaker unit out of the 24 channels of array speakers 1 assumed
by the content producer as a standard The high frequency component of the primary sound
source A is output. Similarly, the high frequency component of the primary sound source B is
output from the 9th speaker unit, and the high frequency component of the primary sound
source C is output from the 21st speaker unit.
[0053]
Similarly, even in the case of array speakers 1a and 1b different from those assumed as the
standard, high frequency components from the speaker unit of the array speaker in the direction
closest to the primary sound source direction viewed from the standard listening position 2
Output For example, in the case of an array speaker 1a of 16 channels, the high frequency
component of the primary sound source A is output from the fourth speaker unit, and the high
frequency component of the primary sound source B is output from the sixth speaker unit, The
high frequency component of the primary sound source C is output from the 14th speaker unit.
Also, in the case of an eight-channel array speaker 1b, the high frequency component of the
primary sound source A is output from the second speaker unit, and the high frequency
component of the primary sound source B is similarly output from the third speaker unit. The
high frequency component of the primary sound source C is output from the seventh speaker
unit.
[0054]
In FIG. 6, the locations of the original primary sound sources A, B and C are known. However, it is
difficult to know the position of the original primary sound source from the signals of 24
channels for wavefront synthesis. In such a case, the standard 24 channel speaker unit is used as
a new primary sound source, and the directions of the standard listening position 2 to 24
channel speaker units can be viewed as the same as possible. Assign a signal to the speaker unit
of
[0055]
FIG. 7 is an explanatory diagram for explaining assignment of speaker units in charge of high
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frequency components exceeding the wave-field synthesis frequency band. Numerals attached to
the speaker units of the array speakers 1 a and 1 b in FIG. 7 indicate the numbers of the speaker
units of the array speaker 1.
[0056]
The assignment of the speaker units in charge of the high frequency components will be
described with reference to FIG. 7. In the case of the 16-channel array speaker 1a, the first
speaker unit of the array speaker 1 is assigned to the first speaker unit from the left. Hereinafter,
the second and third speaker units of the array speaker 1 are sequentially assigned to the second
speaker unit, the fourth speaker unit of the array speaker 1, and so on to the third speaker unit.
Similarly, in the case of the eight-channel array speaker 1b, the first and second speaker units of
the array speaker 1 are assigned to the first speaker unit from the left. Hereinafter, the third to
fifth speaker units of the array speaker 1 are sequentially assigned to the second speaker unit,
and the sixth to ninth speaker units of the array speaker 1 are sequentially assigned to the third
speaker unit.
[0057]
At this time, the time axis is adjusted based on the difference in position with the array speaker 1
as a standard, in order to match the timing with the wavefront synthesis frequency band
component. As described above, by allocating a speaker unit in charge of a high frequency
component exceeding the wave front synthesis frequency band, even when sound is output from
an array speaker different from the standard, the sound field is synthesized by wave front
synthesis. Can be played back.
[0058]
It can be understood by frequency analysis of all channels of the content reproduced by
wavefront synthesis which of the above two examples the actual wavefront synthesis source
uses. Therefore, by performing frequency analysis before content reproduction, it is possible to
set processing for the high frequency by determining which example is used to perform
processing for the high frequency.
04-05-2019
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[0059]
A wavefront synthesis signal conversion apparatus and a wavefront synthesis signal conversion
method according to an embodiment of the present invention are based on such technical ideas.
Hereinafter, a wavefront synthesis signal conversion apparatus and a wavefront synthesis signal
conversion method according to an embodiment of the present invention will be described in
detail.
[0060]
Next, the details of the wavefront synthesis signal conversion apparatus and the wavefront
synthesis signal conversion method according to an embodiment of the present invention will be
described. FIG. 8 is an explanatory diagram for explaining the sound field reproduction device 10
according to the embodiment of the present invention. Hereinafter, the configuration of the
sound field reproduction apparatus 10 according to the embodiment of the present invention will
be described using FIG. 8.
[0061]
As shown in FIG. 8, the sound field reproduction device 10 according to the embodiment of the
present invention includes a data input unit 110, a data decoding unit 112, a demultiplexing unit
114, an audio data decoding unit 120, a meta The data decoding unit 122, the wavefront
synthesis reproduction signal conversion unit 130, the audio output unit 150, the subtitle data
decoding unit 170, the subtitle reproduction unit 172, the video data decoding unit 180, the
video reproduction unit 182, the subtitle super The configuration includes a pause unit 190 and
a display unit 192. The audio output unit 150 includes an amplifier 152 and an array speaker
154.
[0062]
The data input unit 110 is for inputting content data (video data and audio data) to be
reproduced by the sound field reproduction device 10. The input source of the content data may
be, for example, a CD-ROM, a DVD-ROM, or another optical disk having a large capacity of
several hundred mega-gigabytes or more, or may be data received via a network. Content data
04-05-2019
20
input to the data input unit 110 is encoded by a predetermined encoding method, and its
capacity is compressed. The content data input by the data input unit 110 is sent to the data
decryption unit 112.
[0063]
The data decoding unit 112 receives the content data input by the data input unit 110, and
decodes and outputs data encoded by a predetermined encoding method by a decoding method
corresponding to the encoding method. . The data decoded by the data decoding unit 112 is sent
to the demultiplexing unit 114.
[0064]
The demultiplexing unit 114 performs demultiplexing processing on the data decoded by the
data decoding unit 112, and extracts video data, audio data, subtitle data, and metadata. The
extracted data are sent to the audio data decoding unit 120, the metadata decoding unit 122, the
subtitle data decoding unit 170, and the video data decoding unit.
[0065]
The audio data decoder 120 decodes and extracts audio data from the signal demultiplexed by
the demultiplexer 114. The audio data extracted by the audio data decoding unit 120 includes m
channel audio information and sound source position information for forming a virtual sound
source. The audio information can include information such as the type and output level of each
virtual sound source, and the duration of sound. A signal relating to audio data extracted by the
audio data decoding unit 120 is referred to as a wavefront synthesis reproduction signal.
[0066]
The metadata decoding unit 122 decodes and extracts metadata for reproducing audio data,
which is attached to the content data, from the signal demultiplexed by the demultiplexer 114.
The metadata extracted by the metadata decoding unit 122 includes standard reproduction
condition data assumed by the content producer. The standard reproduction condition data
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includes information on the number of channels of the speaker, the distance between the speaker
units constituting the array speaker, and the standard listening position.
[0067]
The information on the standard listening position may be set as an absolute distance from the
center position of the array speaker, and the array speaker based on the total length of the array
speaker calculated from the product of the spacing between the speaker units and the channel
number of the speaker The distance from the center position may be set. When setting the
information on the standard listening position as the distance from the center position of the
array speaker based on the total length of the array speaker, for example, the distance from the
center position of the array speaker is 1 to 2 times the total length of the array speaker It may be
set between.
[0068]
The wavefront synthesis reproduction signal conversion unit 130 receives data output from the
audio data decoding unit 120 and the metadata decoding unit 122, converts the data into a
wavefront synthesis reproduction signal suitable for the configuration of the sound field
reproduction apparatus 10, and outputs the signal. It is.
[0069]
In the wave-field synthesis reproduction signal conversion unit 130, the number of channels of
the speakers of the sound field reproduction apparatus 10 and the spacing of the speaker units
constituting the array speaker (hereinafter, the number of channels of the speakers of the sound
field reproduction apparatus 10 and the speakers constituting the array speaker An interval
between units is generically referred to as “actual reproduction condition” and sent from the
audio output unit 150.
When the assumed reproduction condition and the actual reproduction condition are different by
using the reproduction condition assumed by the content creator and the actual reproduction
condition, as described above, the speaker unit under the assumed reproduction condition A
wavefront synthesis filter can be calculated, in which the position is the primary sound source
position in the sound field reproduction device 10 that is actually reproduced. By calculating the
wavefront synthesis filter, the wavefront synthesis reproduction signal conversion unit 130 can
04-05-2019
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perform conversion processing of the wavefront synthesis reproduction signal for obtaining a
wavefront synthesis reproduction signal suitable for the actual reproduction environment.
[0070]
When the assumed reproduction condition and the actual reproduction condition coincide with
each other, the wavefront synthesis reproduction signal conversion unit 130 does not perform
conversion processing of the wavefront synthesis reproduction signal, and the sound data
decoding unit 120 extracts the signal. The wavefront synthesis reproduction signal may be input
to the sound output unit 150 as it is.
[0071]
The amplifier 152 amplifies the wavefront synthesis reproduction signal generated by the
wavefront synthesis reproduction signal conversion unit 130 for reproduction by the array
speaker 154.
The array speaker 154 outputs sound from n speaker units (not shown). The sound output from
the array speaker 154 is wave-field synthesized to form a wave-front. Further, by outputting the
sound by wave-field synthesis from the array speaker 154, it is possible to virtually arrange the
sound source in the space and reproduce the sound field that the sound is emitted from the
sound source.
[0072]
The subtitle data decoding unit 170 decodes and extracts subtitle data from the signal
demultiplexed by the demultiplexing unit 114. The subtitle reproduction unit 172 reproduces
subtitle data extracted by the subtitle data decoding unit 170. The video data decoding unit 180
decodes and extracts video data from the signal demultiplexed by the demultiplexing unit 114.
The video reproduction unit 182 reproduces the video data extracted by the video data decoding
unit 180. The subtitle superimposing unit 190 performs processing of superposing subtitle data
on video data. The display unit 192 displays the video data in which the subtitle data is
superimposed.
[0073]
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23
The sound field reproducing apparatus 10 according to an embodiment of the present invention
has a wavefront synthesis reproduction signal when the number of speaker units of the array
speaker 154 and the interval between the speaker units are different from those assumed by the
content producer. By performing conversion processing of the wave-field synthesis reproduction
signal to obtain a wave-field synthesis reproduction signal suitable for an actual reproduction
environment by the conversion unit 130, it is possible to reproduce a sound field as expected by
the content producer.
[0074]
In the present embodiment, the display unit 192 is configured as a part of the sound field
reproduction device 10. However, data from the subtitle superimposing unit 190 is output to an
external video display device such as a liquid crystal display or a plasma display. You may do it.
[0075]
The configuration of the sound field reproduction apparatus 10 according to the embodiment of
the present invention has been described above using FIG.
Next, the configuration of the wavefront synthesis reproduction signal converter 130 according
to an embodiment of the present invention will be described.
[0076]
FIG. 9 is an explanatory view for explaining the configuration of the wavefront synthesis
reproduction signal conversion unit 130 according to the embodiment of the present invention.
Hereinafter, the configuration of the wavefront synthesis reproduction signal converter 130
according to the embodiment of the present invention will be described with reference to FIG.
[0077]
As shown in FIG. 9, the wavefront synthesis reproduction signal conversion unit 130 according
to an embodiment of the present invention includes a frequency analysis unit 132, a frequency
band separation unit 134, a filter coefficient generation unit 136, and a high frequency
04-05-2019
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component channel. An allocation unit 138, a wavefront synthesis reproduction signal generation
unit 140, and a signal mixing unit 142 are included.
[0078]
The frequency analysis unit 132 inputs the audio data extracted by the audio data decoding unit
120, and analyzes the frequency of the audio to be reproduced.
The analysis result is sent to the high frequency component channel assignment unit 138.
[0079]
The frequency band separation unit 134 receives the voice data extracted by the voice data
decoding unit 120 and the actual reproduction condition data sent from the voice output unit
150, and has components of frequencies higher and lower than the wavefront synthesis upper
limit frequency. And output separately. The component of the frequency band higher than the
wavefront combining upper limit frequency is sent to the high frequency component channel
allocation unit 138, and the component of the frequency band lower than the wavefront
combining upper limit frequency (wavefront combining band) is sent to the wavefront combining
reproduction signal generating unit 140.
[0080]
The wave front synthesis upper limit frequency is also changed by the angle θ between the
array speaker surface and the wave front as described above (see FIG. 10), but from the multichannel sound source already made for the wave front synthesis reproduction, the original
primary sound source In many cases, the position of is not known, and therefore the upper limit
value of θ is not known. Therefore, in the present embodiment, assuming that θ is
approximately 25 degrees to 40 degrees as a common sound source arrangement, about 1.5
times the value calculated by {(340/2) / speaker unit spacing} [Hz] (≒ A value of about 1 / sin
40 °) to about 2.3 times (≒ 1 / sin 25 °) is set as a wavefront synthesis upper limit frequency
for separation in the frequency band separation unit 134.
04-05-2019
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[0081]
The filter coefficient creation unit 136 receives the standard reproduction condition data
included in the metadata extracted by the metadata decoding unit 122 and the actual
reproduction condition data sent from the audio output unit 150, and uses the standard
reproduction condition as the actual reproduction condition. Filter coefficients of the wave-field
synthesis filter for conversion into
[0082]
The wavefront synthesis filter coefficient for converting the standard reproduction condition into
the real condition is a wavefront synthesis filter when the speaker position (position of the array
speaker 1) in the standard reproduction in FIG. 2 and FIG. 3 is the primary sound source position.
The coefficients are calculated based on the concept as shown in FIG.
The wavefront synthesis filter coefficients are described, for example, in the method described in
Takeda et al., “Study on wavefront synthesis using multi-channel speaker reproduction”, as
described above, in the Proceedings of the Acoustical Society of Japan, pp. 407-408, September
2000. Can be created by
[0083]
A high frequency component channel assignment unit 138 receives the analysis result of the
frequency analysis unit 132 and the m channel high frequency band signal separated by the
frequency band separation unit 134, and outputs a high frequency band. Assignment and
adjustment of the time axis. The signal output by the high frequency component channel
assignment unit 138 is an n channel signal to match the actual reproduction condition.
[0084]
The wavefront synthesis reproduction signal generation unit 140 receives the signal of the
wavefront synthesis band separated by the frequency band separation unit 134 and the filter
coefficient of the wavefront synthesis filter generated by the filter coefficient generation unit
136, and performs wavefront synthesis under the actual reproduction condition. It generates a
wave-field synthesis signal to be performed.
04-05-2019
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[0085]
The wavefront synthesis reproduction signal generation unit 140 generates a wavefront
synthesis signal for performing wavefront synthesis under the actual reproduction condition,
with each channel under the standard reproduction condition as a primary sound source, by
convolution of each channel signal and the wavefront synthesis filter.
The n-channel wavefront synthesis signal generated by the wavefront synthesis reproduction
signal generation unit 140 is sent to the signal mixing unit 142.
[0086]
The signal mixing unit 142 is a speaker unit with real reproduction conditions, including the nchannel wavefront synthesis signal generated by the wavefront synthesis reproduction signal
generation unit 140 and the n-channel signal output from the high frequency component
channel allocation unit 138. It mixes and outputs for every channel. By mixing the wavefront
synthesis band of n channels and the high frequency band in the signal mixing unit 142 for each
channel, an n channel wavefront synthesis reproduction signal under the final real reproduction
condition is generated.
[0087]
The configuration of the wavefront synthesis reproduction signal converter 130 according to the
embodiment of the present invention has been described above with reference to FIG. By
configuring the wavefront synthesis reproduction signal conversion unit 130 in this way, if the
content producer is different from the array speaker assumed when creating the content, the
wavefront synthesis reproduction signal conversion unit 130 is adjusted to the actual
environment. As a result, it is possible to convert the wavefront synthesis reproduction signal.
[0088]
The processing described above may be implemented by providing a storage unit inside the
sound field reproduction apparatus and sequentially calling computer programs stored in the
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storage unit. As the storage unit, various types of ROM (Read Only Memory) may be used.
[0089]
As described above, according to the present embodiment, even if the reproduction array speaker
at the time of sound synthesis is different from the array speaker assumed when the content
creator creates the content, the wavefront is By converting the composite reproduction signal
according to the actual environment, there is no need to recreate the content from the beginning,
and it is possible to standardize content diversion and content production conditions.
[0090]
Although the preferred embodiments of the present invention have been described above with
reference to the accompanying drawings, it goes without saying that the present invention is not
limited to such examples.
It will be apparent to those skilled in the art that various changes or modifications can be
conceived within the scope of the appended claims, and of course these also fall within the
technical scope of the present invention. It is understood.
[0091]
For example, in the above embodiment, the case where the sound is output from the linear array
speaker has been described, but the present invention is not limited to this example. Since wavefield synthesis can be performed with a speaker arrangement other than a linear array speaker,
the unit of the array speaker is standard even when the array speaker is converted between arcs,
L-shaped and U-shaped other than linear ones. The content producer, as in the above
embodiment, performs wave-field synthesis with an actual array speaker as a new primary sound
source, and assigns high-frequency components to a speaker unit in a direction that passes
through the array speaker unit as a standard. Even if the environment is different from the
environment assumed, the wavefront synthesis reproduction signal can be calculated according
to the reproduction device to be actually used to reproduce the synthetic sound field.
[0092]
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It is explanatory drawing explaining the example of the array speaker for wave-field synthetic |
combination reproduction | regeneration and the standard listening position which the content
maker assumed. It is an explanatory view explaining an example of an array speaker different
from an array speaker for wave field synthetic reproduction assumed by a content maker. It is an
explanatory view explaining another example of an array speaker different from an array speaker
for wave field synthetic reproduction assumed by a content maker. It is an explanatory view
explaining setting of a wave field synthetic filter concerning one embodiment of the present
invention. It is explanatory drawing explaining an example in the case of outputting the sound of
a frequency component higher than a wave surface synthetic | combination upper limit
frequency from an array speaker. It is explanatory drawing explaining another example in the
case of outputting the sound of a frequency component higher than a wave surface synthetic |
combination upper limit frequency from an array speaker. It is an explanatory view explaining
assignment of a speaker unit in charge of a high frequency component over a wave field
synthetic frequency zone. It is an explanatory view explaining sound field reproduction device 10
concerning one embodiment of the present invention. It is an explanatory view explaining
composition of wave field synthetic reproduction signal conversion part 130 concerning one
embodiment of the present invention. It is an explanatory view explaining change of wave face
synthetic upper limit frequency.
Explanation of sign
[0093]
1, 1a, 1b Array speaker 2 Standard listening position 10 Sound field reproduction device 110
Data input unit 112 Data decoding unit 114 Demultiplexing unit 120 Audio data decoding unit
122 Metadata decoding unit 130 Wavefront synthesis reproduction signal conversion unit 132
Frequency analysis unit 134 frequency band separation unit 136 filter coefficient generation unit
138 channel allocation unit 140 wavefront synthesis reproduction signal generation unit 142
signal mixing unit 150 audio output unit 152 amplifier 154 array speaker 170 subtitle data
decoding unit 172 subtitle reproduction unit 180 video data decoding unit 182 image Playback
unit 190 subtitle superimpose unit 192 display unit
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