JP3402567B2 - Multi-channel signal processing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to surround reproduction in which multi-channel audio signals are processed and reproduced, and in particular, multi-channel for creating a suitable multi-channel sound field in a listening room such as an ordinary home. The present invention relates to a signal processing method and device.

[0002]

2. Description of the Related Art As a system for reproducing a multi-channel audio signal, a 3-1 system in high definition (front left L
ch, right Rch, center Cch, surround Sch), Dolby Surround 4ch matrix system (Pro Logic), and discrete system (AC-3). In particular, many American movies have a surround track that has been subjected to Dolby Surround audio processing, and in a movie theater, decoding is performed and each signal is supplied to a plurality of speakers for reproduction. When this is created as video software, surround-processed sound is copied as it is and is commercially available. As a result, many video tape softwares, laser discs, and DVD discs that have been subjected to Dolby Surround processing have been sold.

[0003]

By the way, in order to adjust the sound field in multi-channel reproduction using a plurality of speakers as described above, it is general to adjust the sound field by the level and the delay amount. There are various restrictions on the listening room in which is created. In particular, when the listener approaches the front screen in order to see the image clearly, as in the case of accompanying the image, the listener may inevitably approach the front speaker and lose the sound field balance with the rear speaker. Here, it becomes particularly noticeable when the rear speaker is located far away, and the rear sound becomes low and is canceled out, resulting in a stereo sound field only in the front. For example, as shown in the characteristic diagram of distance-intensity level shown in FIG. 25, as seen from the intensity level of the vertical axis relating to the sense of hearing in the vicinity of the front (this is inversely proportional to the square of the horizontal axis), only the front is dominant. become.
On the other hand, when the speaker moves away from the screen and approaches the rear speaker, the rear sound becomes dominant in the rear as shown in FIG.
The sound from the rear may be abnormally loud and unpleasant.

Therefore, although it is necessary to adjust the sound field according to the position of the listener, various methods have been proposed for detecting the position of the listener. For example, Japanese Patent Publication 1-611
As disclosed in Japanese Patent Laid-Open No. 90, there is a device that detects the position of a listener by transmitting an optical signal and an acoustic signal from the position of the listener and receiving and calculating them on the acoustic device side. Further, as in Japanese Patent Laid-Open No. 1-276900, by using a speaker as a part of a sensor (a sounding body) for detecting the position of the listener, the position of the listener at an arbitrary position in the sound field space can be determined. There is something that makes it detectable. Further, as disclosed in Japanese Patent Application Laid-Open No. 2-184196, there is one that detects the position of a listener by obtaining data corresponding to the position of the remote control transmitter based on the received data from a plurality of remote control receivers. is there. However, although it is necessary to make them constant without adjusting the left and right sound field balances, since these detection positions are the distances from the speakers, only the unbalance is adjusted. , It is not possible to detect the front and rear position information of the listener and adjust the sound field by the stereo sound field in a wide sound field range accordingly.

As described above, in order to adjust the sound field at an arbitrary position in multi-channel reproduction, it is general to add a delay amount according to the level setting and the distance (position). Although we try to make adjustments so that it is easy to hear, as can be understood from the characteristic diagram shown in FIG. 25, it gets crazy when approaching the speaker side after adjusting the sound field.
The actual situation is that it cannot be adjusted to a wide range by adjusting the fixing once.

Therefore, the present invention has been made in view of the above-mentioned points, and it is possible to adjust the sound field so that it can be used in a wide range by correcting the sound field by the stereophonic sound field according to the position of the listener. It is an object of the present invention to provide a multi-channel signal processing method and apparatus capable of performing the above.

[0007]

In order to achieve the above-mentioned object, a multi-channel signal processing method and apparatus according to the present invention comprises a pair of speakers arranged at a front position and a rear position which are substantially symmetrical to a listener. A multi-channel signal processing method and device for reproducing a multi-channel signal including a pair of left and right front stereo signals and a rear signal from a pair of loudspeakers arranged in Filter processing steps and means for outputting a pair of left and right filtered rear processed signals for realizing a convolver in which a filter coefficient based on the filter coefficient is set, and a pair of left and right rear processed signals filtered by the filtering step Adding steps and means for adding to the front stereo signal, and before adding to the front stereo signal First level setting step and means for adjusting / setting the level of the pair of left and right rear processed signals, and second level setting for adjusting / setting the level of the rear signal according to the adjusted / set level of the rear processed signal. And steps and means.

Further, the step and means for supplying the output signal of the adding step and means to the pair of speakers arranged at the front position and the rear signal after the second level setting step and means are arranged at the rear position. It further comprises a step and means for supplying to the pair of speakers.

Further, it further comprises a position information supplying step and means for supplying the position information of the listener, wherein the first level setting step and means adds the level information of the stereo signal according to the position information. It is characterized in that the level of the rear processed signal is adjusted and set.

Further, the position information supplying step and means supplies the position information by the forward movement and / or the backward movement of the listener.

The multi-channel signal is an AC-3 system signal having a 5-channel structure including a front stereo signal of 2 channels, a center channel signal of 1 channel, and a rear signal of 2 channels. It is characterized by further comprising a center addition step and means for attenuating the center channel signal and adding it to the pair of left and right front stereo signals between the addition step and the addition step.

The multi-channel signal is DV
A wideband audio signal recorded on a D audio disc, further comprising a decoding process step of decoding the signal recorded on the DVD audio disc before the filtering process step and the adding step. Is.

Further, the filtering process steps and means, for each channel of the pair of left and right rear signals, the filter coefficient Hl and Hr is Hl = (SF-AK) / (S 2 -A 2) Hr = (SK- ^{AF) / (S 2 -A 2} ) ( however, S is the transfer function of the transfer function from a pair of speakers to the same side of the ear of the listener, a is a pair of speakers to the opposite ear of the listener, F Is the transfer function from the position where the sound image is localized to the ear on the same side of the listener, and K is the transfer function from the position where the sound image is localized to the ear on the opposite side of the listener)
On the basis of the filter processing outputs respectively set to the filter output and the filter processing output having the filter coefficient set to Hl and the filter processing output having the different filter coefficients Hr of the other channels are respectively added, and the pair of addition outputs are filtered. It is characterized in that it is output as a pair of left and right rear processed signals that have been processed.

In the filtering step, the filter coefficient P is P = (F + K) / (S + A) (where S is the transfer function from the pair of speakers to the ear on the same side of the listener, and A is the pair of speakers). To the opposite ear of the listener, F is the transfer function from the position where the sound image is to be localized to the ear on the same side of the listener, and K is the opposite ear of the listener from the position where the sound image is desired to be localized. Transfer function up to)
And a first filtering output obtained by filtering the sum signal of the pair of left and right rear signals and a pair of left and right rear signals with the filter coefficient N set to N = (F−K) / (S−A) Of the first and second filtered outputs based on the second filtered output obtained by filtering the difference signal of Is output as a rear-processed signal of.

Further, a multi-channel signal processing method and apparatus according to another invention is such that a pair of left and right front parts are provided from a pair of loudspeakers arranged at a front position and a pair of loudspeakers arranged at a rear position which are substantially symmetrical to a listener. A multi-channel signal processing method for reproducing a multi-channel signal including a stereo signal and a rear signal, the filter realizing a convolver in which a filter coefficient based on a head-related transfer function is set for the front stereo signal. A filtering step and means for outputting a pair of processed left and right front processed signals; an addition step and means for adding a pair of left and right front processed signals filtered by the filtering step to the left and right rear signals; A first for adjusting and setting the levels of the pair of left and right front processed signals to be added to the rear signal And Bell setting step and means, and has a second level setting step and means for adjusting and setting the level of the front stereophonic signals in response to the adjusting and setting the level of the front processing signal.

Further, a step and means for supplying the output signal of the adding step and means to a pair of speakers arranged at the rear position, and a front stereo signal having passed through the second level setting step and means to the front position. It further comprises a step and means for supplying to the pair of arranged speakers.

Further, the apparatus further comprises a position information supplying step and means for supplying the position information of the listener, wherein the first level setting step and means adds to the level of the rear signal according to the position information. It is characterized in that the level of the forward processing signal is adjusted and set.

Further, the position information supplying step and means is characterized in that position information is supplied by the forward movement and / or backward movement of the listener.

Further, the multi-channel signal is an AC-3 type signal having a 5-channel structure including a front stereo signal of 2 channels, a center channel signal of 1 channel and a rear signal of 2 channels, and the center channel signal is attenuated. It is characterized by further comprising a center adding step and means for adding to the pair of left and right front stereo signals.

The multi-channel signal is DV
A wideband audio signal recorded on a D audio disc, further comprising a decoding processing step and means for decoding the signal recorded on the DVD audio disc.

Further, the filter processing step and means are provided for each channel of the pair of left and right front stereo signals.
Filter coefficient Hl and Hr is Hl = (SF-AK) / (S 2 -A 2) Hr = (SK-AF) / (S 2 -A 2) ( however, S is the same side of the listener from a pair of speakers To the ear, A is the transfer function from the pair of speakers to the ear on the opposite side of the listener, F is the transfer function from the position where the sound image is to be localized to the ear on the same side of the listener, and K is the sound image. (Transfer function from the position to be localized to the ear opposite the listener)
On the basis of the filter processing outputs respectively set to the filter output and the filter processing output having the filter coefficient set to Hl and the filter processing output having the different filter coefficients Hr of the other channels are respectively added, and the pair of addition outputs are filtered. It is characterized in that it is output as a pair of left and right processed front stereo signals.

Further, in the filtering step and means, the filter coefficient P is P = (F + K) / (S + A) (where S is a transfer function from a pair of speakers to the ear on the same side of the listener, and A is a pair). From the speaker to the ear on the opposite side of the listener, F is the transfer function from the position where the sound image is to be localized to the ear on the same side of the listener, and K is the position where the sound image is to be localized from the opposite side of the listener. Transfer function to the ear)
And a first filtering output obtained by filtering the sum signal of a pair of left and right front stereo signals, and a pair of left and right fronts when the filter coefficient N is set to N = (F−K) / (S−A). A sum signal and a difference signal of the first and second filtered outputs are obtained based on the second filtered output obtained by filtering the difference signal of the stereo signal, and the sum signal and the difference signal are filtered. It is characterized by outputting as a pair of left and right front stereo processed signals.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The multi-channel signal processing method and device according to the present invention can be adjusted so that the sound field can be used in a wide range by performing sound field correction according to the stereophonic sound field according to the position of the listener. And a multi-channel signal including a pair of left and right front stereo signals and a rear signal is reproduced from a pair of loudspeakers arranged in a front position and a pair of loudspeakers arranged in a rear position which are substantially symmetrical to the listener. When performing, a filtering step and means for outputting a pair of left and right rear processed signals that have been filtered to realize a convolver in which a filter coefficient based on a head related transfer function is set for the rear signal, and the filtering step An addition step and means for adding a pair of left and right rear processed signals filtered by the above to the left and right front stereo signals; A first level setting step and means for adjusting and setting the level of the pair of left and right rear processed signal to be added to the stereo signal, and adjustment of the rear processing signal
It has a second level setting step and means for adjusting and setting the level of the rear signal according to the setting level.

<First Embodiment> FIG. 1 is a block diagram showing a first embodiment of an apparatus for carrying out the above-described multi-channel signal processing method of the present invention. In FIG. 1, reference numeral 1 is a decoder corresponding to the AC-3 system of Dolby Laboratories.
And rear-channel surround signal SL, SR of 2 channels, 5
The ch signal and the low frequency signal of 100 Hz or less are decoded and separated. Normally, the low frequency signal is reproduced by a super woofer or distributed to each channel, but in this embodiment, the low frequency signal is omitted for the sake of easy understanding of the description.

Reference numeral 2 designates a pair of speakers 3L which are arranged in a front position substantially symmetrical to the listener as shown in FIG. 2A for the 5ch signal decoded and separated by the decoder 1.
3R and a pair of speakers 3SL, 3 arranged at the rear position
The signal processing means for reproducing from the SR is shown. The signal processing means 2 has a left side having a pair of convolvers in which a coefficient based on the head related transfer function is set for each channel of the rear surround signals SL and SR. Right sound image localization filters 21a and 21b, similar right and left sound image localization filters 2
1c and 21d, the level of the center channel signal C is 3d
An attenuator 21e for attenuating B, and adders 21f and 2 for adding the center channel signal C attenuated through the attenuator 21e to the two-channel front stereo signals L, R.
It is equipped with 1g. Note that FIG. 2B shows a case where a center speaker C is further arranged in comparison with FIG.

The left and right sound image localization filters 21a are also provided.
And 21c output signals and right and left sound image localization filter 2
Adder 21 for adding the output signals of 1b and 21d, respectively
h and 21i, the adder 21 according to the set coefficient g _fr
Attenuators 21j and 21k for adjusting the levels of the output signals of h and 21i, and an adder that adds the rear processed signal via the attenuator 21j to the output signal of the adder 21f and supplies the added output to the speaker 3L. 21l, similarly, adder 21g of the output signal to the attenuator 21k adds the rear processing signal through the adder supplied to the speaker 3R of the addition output 21m, the rear surround signals SL in accordance with the coefficient g _r is set It includes an attenuator 21n for adjusting the level and supplying it to the speaker 3SL, and an attenuator 21o for adjusting the level of the rear surround signal SL according to the coefficient g _r which is similarly set and supplying it to the speaker 3SR.

Further, 4 is an input unit for supplying the position information of the listener, and 5 and 6 are for adjusting and setting the level of the rear processed signal to be added to the levels of the front stereo signals L and R according to the position information. Coefficient g _fr and rear surround signal S
A table conversion unit and a coefficient setting unit that form level setting means for setting the coefficient g _r for adjusting and setting the L and SR levels. The table converting unit 5 includes, for example, a listener as shown by a solid line in FIG. coefficient g _fr of the attenuator 21j and 21k and 21n and 21o varies according to the position, g _r is set, the coefficient from the table conversion unit 5 based on the position information from the input unit 4 g _fr and g _r is obtained and coefficient setting unit 6
To the attenuators 21j and 21k, 21n and 21o, respectively.

Here, the rear surround signals SL, S
The pair of left and right sound image localization filters 21a and 21b, 21d and 21c provided for each R channel are, as shown in FIG. 3, ATAL-SCHROEDER that cancels the spatial characteristic from the speaker. By using a type filter, processing is performed so as to localize the sound image to the left side and the right side of the listener, and the sound is localized to the front two-channel stereo signals L and R, respectively.

The ATAL-SCHROEDER shown in FIG.
The type of filter is a combination of the sound image localization filter and the crosstalk canceling filter array shown in FIG.
It is configured for one sound image. That is, looking at one channel, the configuration shown in FIG. 4 is obtained. The configuration of the sound image localization filter circuit of FIG. 4 includes a sound image localization filter that is a portion that convolves the localization position characteristics F and K, and a crosstalk canceling filter array, and the crosstalk canceling filter array portion is ATAL-SCHRO.
It corresponds to the EDER filter. In FIG. 4, S represents the transfer function from a pair of speakers to the ear on the same side, while A
Represents the transfer function to the opposite ear. Since the speakers are symmetrical with respect to the listener, the transfer function from each speaker to both ears is also symmetrical.

Output signals X'from the speakers LF and RF,
Y 'is, X' = become (SX-AY) / (S 2 -A 2) Y '= (SY-AX) / (S 2 -A 2). To perform sound image localization, a signal obtained by convolving a transfer function in a desired localization direction is input to X and Y inputs. That is, when X = Fx and Y = Kx are input, X ′ = [(SF−AK) / (S ² −A ² )] × x = Hl ·
x Y '= [(SK-AF) / (S ² -A ² )] x = Hr
x, and sound image localization is realized. The filter is this Hl,
It has Hr as a coefficient.

Returning to FIG. 3, S is the transfer function from the pair of speakers to the ear on the same side of the listener, A is the transfer function from the pair of speakers to the ear on the opposite side of the listener, and F is the sound image localization. Transfer function from the desired position to the ear on the same side of the listener,
K represents the transfer function from the position where the sound image is desired to be localized to the ear opposite to the listener. Since the speakers are symmetrical with respect to the listener, the transfer function from each speaker to both ears is also symmetrical. Outputs from the actual speakers 3L and 3R arranged at symmetrical positions in front of the listener are X ′,
Y '. In order to localize an arbitrary sound image around the listener by the two front speakers 3L and 3R, the transfer functions F and K from the target position to be localized to the listener are convoluted into the input signal, and then the front Speaker 3
Processing for canceling the spatial characteristics from L, 3R to the listener is performed. First, the latter spatial characteristic canceling process will be described.

The outputs x and y at both ears by the speakers 3L and 3R arranged at the front left and right symmetrical positions are represented by x = SX '+ AY' y = AX '+ SY', and these outputs are output to the cancel filter. Input X,
I want to make it equal to Y, so input x and y
Can be expressed as X = SX ′ + AY ′ Y = AX ′ + SY ′. Therefore, based on this equation, for the inputs X and Y, the outputs X ′ and Y ′ from the speaker are X ′ = ( ^{SX-AY) / (S 2} -A 2) (1.1) Y '= a (SY-AX) / (S 2 -A 2) (1.2).

Next, consider the convolution of the transfer function in the direction to be localized. In FIG. 3, when the signal x is reproduced from the speaker (position Xp) on the rear left side of the listener, the listener's left ear L
At -ear and right ear R-ear, signals Fx and Kx are obtained by convolving transfer functions F and K, respectively. Sound image localization can be realized by applying this signal to the inputs X and Y.

That is, in FIG. 3, X = Fx, Y = K
When inputting to the formula (1.2) as x, X ′ = [(SF-AK) / (S ² −A ² )] · x = H1 · x (2.1) Y ′ = [(SK-AF) / become (S ² -A ^2)] · x = Hr · x (2.2 ). This concludes the convolution of the transfer function and the canceling process of the spatial characteristic into the filter coefficients Hl and Hr. Since this is the case where the speaker is at the rear left position Xp of the listener, in FIG. 3, the filter coefficient Hl indicates the filter 21a and the filter coefficient Hr indicates the filter 21b.
, And takes the original signal x as its input. In order to create another sound image of the input signal y on the rear right side, since it is symmetrical in the same way, the filters are switched left and right and input as 21c and 21d.

Therefore, in order to localize the sound image at two positions in front of the listener, which are substantially symmetrical to each other, a pair of left and right sound image localization filters 21a provided for each channel of the rear surround signals SL and SR. And 21b,
Four FIs having 21d and 21c as filter coefficients Hl and Hr shown in the equations (2.1) and (2.2).
By using an R filter, sound image localization can be performed.

By the above operation, the decoder 1 shown in FIG.
Of the 5ch signals decoded and separated from, the 2-channel stereo signals L, R are added by the adders 21f, 21g, 21
Stereo speakers 3L, 3R such as a television arranged at a front position substantially symmetrical to the listener via the 1 and 21m.
And the center channel signal C is reproduced by the attenuator 21.
After the level is lowered by 3 dB via e, the adder 2
It is distributed to the speakers 3L and 3R via 1f and 21g.

The rear surround signals SL and SR are
Filtering is performed so as to localize the sound image to the left side and the right side of the listener via a pair of left and right sound image localization filters 21a and 21b, and 21c and 21d using an ATAL-SCHROEDER type filter as shown in FIG. Then, the adders 21h and 21i and the attenuators 21j and 2 for which the coefficient g _fr according to the position information of the listener is set.
By being added to the front two-channel stereo signals L and R via 1k and the adders 21l and 21m,
The listener can enjoy the moving sound by being surrounded by the sound image of 5ch while watching the television in front, while the rear surround signals SL and SR themselves are set with the coefficient g _r according to the position information of the listener. The sound is reproduced by the speakers 3SL and 3SR arranged in a rear position substantially symmetrical to the listener via the attenuators 21n and 21o.

That is, as shown in FIG. 2 (A), by providing a pair of speakers 3L, 3R on both sides of the display monitor, the level can be changed from the position shown in FIG. 2 (B) according to the position of the listener. The rear surround signals SL and SR, which are adjusted and set, are reproduced, and stereoscopic surround sound can be reproduced by the stereo signal from the front and the rear stereo signal (rear surround) that is localized rearward, and at the same time, the rear surround can be reproduced. The signal itself is reproduced by the rear speakers 3SL and 3SR.

Here, as shown in FIG. 5, the speakers 3L and 3R for the front stereo signals arranged in front of the dotted line are shown.
And rear speakers 3SL and 3SR arranged in the rear position
When the listener is in the center between the speakers 3L and 3R and 3SL and 3SR with respect to the intensity level (power) of and, the normal reproduction is performed as described above, but the listener is If you move forward or backward, you get:

That is, when the listener moves forward, the listener manually inputs the position information to the input section 4 or the distances to the four speakers are obtained using an infrared sensor or the like accordingly. When position information is input to the input unit 4 by a detection unit (not shown) for calculating the front-rear position, the attenuator in the table conversion unit 5 changes the level of the rear processed signal from zero to the enhancement direction with respect to the level of the front stereo signal. The coefficients g _fr of 21j and 21k are adjusted and set. Then, in the areas other than the listening area, the attenuators 21j and 21k
The coefficient g _fr has a value of 2 and is constant. by this,
As shown by the alternate long and short dash line in FIG. 5, the rear sound can be clearly heard even from the front speaker by adding the rear processing signal by the coefficient g _fr setting. On the other hand, when the listener moves rearward from the center, the level of the rear processed signal becomes infinitely zero, and the level of the rear signal is attenuated by setting the coefficient g _r of the attenuators 21n and 21o. The rear sound output from the 3SR is adjusted so as not to be noisy. As a result, the power of the rear signal output from the loudspeakers 3SL and 3SR is attenuated as shown by the alternate long and short dash line in FIG.

Therefore, as described above, when the listener moves forward or backward from the center, the coefficients g _fr and g _{r of the} attenuators 21j and 21k, 21n and 21o are set according to the positional information that moves in the front-back direction. As a result, the sound volume output from the speakers 3L and 3R, 3SL, and 3SR is corrected, and as a result, the sound field is corrected by the stereophonic sound field according to the position of the listener, and the sound field can be used in a wide range. To be done. In the above embodiment, the adders 21l and 21m perform addition and supply to the speakers 3L and 3R. However, the speakers 3L and 3R reproduce the outputs of 21f and 21j, respectively, and the two speakers 3L1 and 3L2, and 21g and 21k. The output of 1 may be supplied to the two speakers 3R1 and 3R2 for reproduction, and added in space, or substantially added. This point can be applied not only to the first embodiment but also to the following embodiments, and the pair of speakers in the claims should be construed to include the composite speaker as described above.

<Second Embodiment> FIG. 6 is a block diagram showing a second embodiment of an apparatus for carrying out the multi-channel signal processing method of the present invention. In the above-described first embodiment, a filter that performs a pair of sound image localization processing on each of the rear surround signals SL and SR is required for each channel, that is, four filters are used to localize the sound image at two locations. A filter is required, the scale of hardware becomes large, and it cannot be used for consumer products such as a television receiver. In the second embodiment,
This is effective when performing sound image localization at a symmetrical position with respect to the median plane that divides the listener's head symmetrically, and the number of filters used is half that of the first embodiment shown in FIG. By doing so, the above-mentioned problems are solved.

That is, in the second embodiment shown in FIG. 6, the signals of 5 channels decoded and separated by the decoder 1 are arranged in symmetrical positions in front of the listener, for example, for two channels of a television receiver TV. Stereo speakers 3L, 3R and rear speaker 3SL arranged at the rear position
And as signal processing means 2 for reproducing from 3SR,
The signal processing of the rear surround signals SL and SR is performed so as to localize the sound image to the rear of the listener, and the sound image localization circuit 22a for reproducing from the front two-channel stereo speakers 3L and 3R and the level of the center channel signal C are attenuated by 3 dB. The attenuator 22b and adders 22c and 22d for adding the center channel signal C attenuated through the attenuator 22b to the two-channel stereo signals L and R are provided.

An amplifier 22e for correcting the levels of the rear surround signals SL and SR via the sound image localization circuit 22a on the basis of a coefficient g ₁ + α (= g _fr ) for adjusting / setting according to the position of the listener. And 22f and the adder 22c
L of the rear surround signal that has passed through the sound image localization circuit 22a and amplifiers 22e and 22f to the signal that has passed through
And R channel signal are added respectively and speaker 3L
And and adder 22g and outputs the 3R 22h, listener and corrected respectively based on the coefficient 1-g ₁ be adjusted and set in accordance with the level of the rear surround signals SL and SR to the position of the listener (= g _r) Speaker 3SL placed in the rear position
And amplifiers 22i and 22j for outputting to 3SR.

Further, in the embodiment shown in FIG. 6,
As means for inputting the coefficients g ₁ + α and 1-g ₁ set in the amplifiers 22e and 22f, 22i and 22j, distance detecting means 7 for detecting the distance between the listener moving back and forth and the detected value. The position calculation / coefficient input unit 8 is provided for calculating the position of the listener based on the above and inputting the coefficients g ₁ + α and 1-g ₁ according to the position information.

Here, the distance detecting means 7 is not shown.
4 speakers and listeners using infrared sensors
The position calculation / coefficient input unit 8
Calculates the front-back position of the listener based on the detected value
The coefficient g according to the position information 1 + α and 1-g₁Amplifies
Input to the containers 22e and 22f, 22i and 22j. So
In this case, the position calculation / coefficient input unit 8
Coefficient g corresponding to the front-back position of the listener_fr(= G₁ +
α) and g_r(= 1-g₁) Related coefficient g₁ + Α and g₁ 
Is set and the listener moves forward from the center.
The amplifiers 22e and 22f have a coefficient g₁ + Α is entered
The amplifiers 22i and 22
coefficient 1-g for j₁Is input and is working
It

Further, as the sound image localization circuit 22a,
Japanese Patent Application Laid-Open No. 8-51698 proposed by the applicant of the present invention
Shuffler as shown in the publication
Use a filter. The structure of this shuffler filter is shown in FIG.
Shown in. In FIG. 8, 22a ₁ is a first adder for obtaining a sum signal of the pair of left and right rear surround signals, 22a ₂
Is a second adder for obtaining a difference signal between the pair of left and right rear surround signals, and 22a ₃ is a first adder for processing an output of the _first adder 22a ₁ with a filter coefficient P described later being set.
Second filter 22a ₄ is provided with a filter coefficient N, which will be described later, and processes the output of the _second adder 22a ₂ .
22a ₅ is a third adder for obtaining a sum signal of the signals processed by the first and second filters, and 22a ₆ is a difference signal of the signals processed by the first and second filters. A fourth adder to obtain the third and fourth adders 22
The outputs of a ₅ and 22a ₆ are output as a pair of left and right rear surround signals that have been filtered.

Here, when the 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 ′, Y ′ results in X ′ = N (X−Y) + P (X + Y) Y ′ = P (X + Y) −N (X−Y). It has been shown that a hula filter can be configured,
The filter coefficients P and N are given by P = 1 / (S + A) (3.1) N = 1 / (S-A) (3.2). The output signal X ', Y' is, X '= [2 (SX-AY)] ^{/ (S 2 -A 2) (} 4.1) Y' = [2 (SY-AX)] / (S ² -A ² ) (4.2), and the same results as the expressions (1.1) and (1.2) of the first embodiment are obtained. However, since it has a doubled value, it has a gain of 6 dB.

Then, the numerator of the formulas (3.1) and (3.2) is represented by P = (F + K) / (S + A) (5.1) S = (F−K) / (S−A) (5. if 2), X '= [2 (SFX + SKY-AFY- AKX) ] ^{/ (S 2 -A 2) (} 6.1) Y' = [2 (SFY + SKX-AFX- AKY) ] / (S ² - A ² ) (6.2) is obtained.

This means that when the inputs X = x and Y = 0, the same results as the expressions (2.1) and (2.2) can be obtained.
On the other hand, when the input is X = 0 and Y = y, X ′ = Hr · y (7.1) and Y ′ = Hl · y (7.2). This indicates that when y is input, the sound image is localized at a position symmetrical to the sound image position input to x, and when signals are respectively input to x and y, the superposition theory holds, The sound image is localized at symmetrical positions.

Therefore, according to the second embodiment,
With the sound image localization circuit 22a for the rear surround signals SL and SR
Then, using a shuffler filter, sound is heard on the left and right sides of the listener.
Performs processing so as to localize the image, and changes according to the position of the listener.
Several g_frVia the amplifiers 22e and 22f whose
And add to front 2 channel stereo signal L, R
In addition, the rear surround signals SL and SR are listeners.
Coefficient g depending on the position of Amplifier 22 whose r is adjusted and set
By outputting via i and 22j,
The listener, as shown in FIG.
While watching the TV receiver, move around surrounded by the sound image of 5ch
You can enjoy the sound and get a high sense of presence.
In addition, the number of filters used is different from that of the first embodiment shown in FIG.
Only half the number is needed, and the configuration can be simplified.
To reduce it and incorporate it into a consumer television receiver.
It will be possible. At that time, depending on the position of the listener
The sound field can be adjusted to a wide range by performing sound field correction using the three-dimensional sound field.
It can be adjusted for use in enclosures.

In the description of each of the above embodiments, the AC-3 system developed by Dolby Laboratories is used as an example of the 5ch audio signal, but the present invention is not limited to this, and the surround signal is not used. SDDS (Sony Dynamic Digital) divided into 2 channels of L and R
Sound), DTS (Digital Theat)
er Sound) and other signal format standards.

<Third Embodiment> Next, FIG. 9 shows the matrix of the present invention.
Implementation of a device for implementing the multi-channel signal processing method
It is a block diagram which shows the state 3. With the second embodiment shown in FIG.
Explaining only the difference, in the third embodiment shown in FIG.
Between the adders 22c and 22g and between the adders 22d and 2
Amplifiers 22k and 22l are installed between 2h and
And the coefficient g for the amplifiers 22e and 22f 1 (=
g_fr) Depending on the setting of
Number 1-g₁(= G_f) Is set. Sanawa
The speaker 3L in front of the position detection / coefficient input unit 9
And amplifiers 22e and 22f and amplifiers 22k and 22k for 3R
And the coefficient g of 22 l₁And 1-g₁To automatically specify the coefficient g
_fAnd g_frAdjust while keeping the volume of the surroundings constant.
There is. The coefficient related to the rear speakers 3SL and 3SR is 1
Fixed. With the rear speakers 3SL and 3SR and the listener
Are far enough apart, and are placed high, down behind
If you don't feel the noise behind you
As described above, the level of the rear speaker may be constant.

In the first to third embodiments, the levels of the pair of left and right rear processed signals to be added to the front stereo signal are adjusted and set according to the position of the listener, and the adjusted and set levels of the rear processed signals are set. However, in the following fourth to sixth embodiments, the levels of the pair of left and right front processed signals to be added to the rear signal are adjusted and set according to the position of the listener. In addition, the invention for adjusting and setting the level of the forward signal according to the adjustment and setting level of the forward processed signal will be described.

That is, a multi-channel signal processing method and apparatus according to another invention comprises a pair of left and right front parts from a pair of loudspeakers arranged at a front position and a pair of loudspeakers arranged at a rear position which are substantially symmetrical to a listener. A multi-channel signal processing method for reproducing a multi-channel signal including a stereo signal and a rear signal, the filter realizing a convolver in which a filter coefficient based on a head-related transfer function is set for the front stereo signal. A filtering step and means for outputting a pair of processed left and right front processed signals; an addition step and means for adding a pair of left and right front processed signals filtered by the filtering step to the left and right rear signals; Adjust and set the level of the pair of left and right front processed signals to be added to the rear signal. And level setting step and means,
A second level setting step and means for adjusting and setting the level of the front stereo signal according to the adjustment and setting level of the front processed signal.

<Fourth Embodiment> FIG. 10 is a block diagram showing a fourth embodiment of an apparatus for carrying out a multi-channel signal processing method according to another invention. In the configuration shown in FIG. 10, the same parts as those in the first embodiment shown in FIG. 1 are designated by the same reference numerals, and their description will be omitted. Adders 21f and 21g
The front stereo signals L and R to which the center channel signal C attenuated by the subtractor 21e are added by the amplifier 21p for adjusting / setting the output level according to the coefficient g _f set according to the position of the listener. And 21q
2A, it is supplied to a pair of speakers 3L and 3R arranged at a front position substantially symmetrical to the listener as shown in FIG.

The front stereo signals L and R that have passed through the adders 21f and 21g are input to the left and right sound image localization filters 21a and 21b and 21c and 21d, respectively, and the left and right sound sources are added by the adders 21h and 21i. Output signals of the sound image localization filters 21a and 21c are added together with the sound image localization filters 21b and 21 on the right and left sides.
The output signals of d are added, and the output levels of the added outputs are adjusted by the attenuators 21j and 21k according to the coefficient _grf set according to the position of the listener. Rear surround signals SL and SR output from the decoder 1
Is added to the attenuator 21j via the adders 21r and 21s.
2 and 21k are added to the pair of left and right front processed signals, respectively, and the speaker 3S is added as shown in FIG.
L and 3SR.

Here, the pair of left and right sound image localization filters 21a and 21b, 21d and 21c provided for each channel of the front stereo signals L and R are, as shown in FIG. ATAL-SCHROEDER to cancel the characteristics
Using a Schrader type filter, processing is performed so that the sound image is localized on the left side and the right side of the listener, and is added to the rear surround signals SL and SR, respectively.

The ATAL-SCHROEDE shown in FIG.
The R type filter is a combination of the sound image localization filter and the crosstalk canceling filter array shown in FIG. 12 configured for two sound images. That is, looking at one channel, the configuration is shown in FIG. The configuration of the sound image localization filter circuit of FIG.
Is composed of a sound image localization filter that is a convolution part and a crosstalk canceling filter array, and the crosstalk canceling filter array part is the ATAL-SC
Corresponds to the HROEDER filter. In FIG.
S represents the transfer function from the pair of speakers 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.

[0060] Speaker 3SL, the output signal X from the 3SR ', Y' is, X '= (SX-AY ) / (S 2 -A 2) Y' = (SY-AX) / (S 2 -A 2) Becomes To perform sound image localization, a signal obtained by convolving a transfer function in a desired localization direction is input to X and Y inputs. That is, when X = Fx and Y = Kx are input, X ′ = [(SF−AK) / (S ² −A ² )] × x = Hl ·
x Y '= [(SK-AF) / (S ² -A ² )] x = Hr
x, and sound image localization is realized. The filter is this Hl,
It has Hr as a coefficient.

Returning to FIG. 11, S is the transfer function from the pair of speakers to the ear on the same side of the listener, A is the transfer function from the pair of speakers to the ear on the opposite side of the listener, and F is the sound image localization. The transfer function from the desired position to the ear on the same side of the listener, K indicates the transfer function from the position where the sound image is desired to be localized to the ear on the opposite side 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. Outputs from the actual speakers 3SL, 3SR arranged at symmetrical positions behind the listener are X ', Y'. Two rear speakers 3SL, 3
In order to localize an arbitrary sound image around the listener by SR, the transfer functions F and K from the target position to be localized to the listener are convoluted with the input signal, and then received from the rear speakers 3SL and 3SR. It suffices to perform the process of canceling the spatial characteristic up to the listener, and in the same manner as in the first embodiment, the outputs of the speakers 3SL and 3SR are expressed by the formula (2.
1) and (2.2) can be obtained, and the convolution process of the transfer function and the cancellation process of the spatial characteristic are summarized in the filter coefficients Hl and Hr.

Therefore, in order to localize the sound image at two positions which are substantially symmetrical to the rear of the listener, a pair of left and right sound image localization filters 21a provided for each channel of the front stereo signals L and R are provided. And 21b and 21d
And 21c are composed of four FIR filters having Hl and Hr shown in the equations (2.1) and (2.2) as filter coefficients, it is possible to perform sound image localization.

By the above operation, of the 5ch signals decoded and separated from the decoder 1 shown in FIG. 10, the 2-channel stereo signals L and R have the adders 21f and 21g and the coefficient g _f according to the position of the listener. Amplifier 21 to be set
Stereo speakers 3L, 3R, such as a television, which are arranged at a front position substantially symmetrical to the listener via p, 21q.
And the center channel signal C is reproduced by the attenuator 21.
After the level is dropped by 3 dB via e, the adder 21
The speakers 3L, 3R and the speaker 3S arranged at a rear position substantially symmetrical to the listener via the f and 21g.
It is distributed to the L and 3SR sides. Further, the rear surround signals SL and SR are attenuators 21j and 21k whose coefficients _grf are set by the adders 21r and 21s according to the position information.
Are added to the front two-channel stereo signals L and R subjected to the sound image localization processing via the speakers 3SL and 3SR.
Will be played back, and the listener can enjoy the moving sound while watching the TV in front and surrounded by the sound image of 5ch.

Here, the coefficient g _rf of the attenuators 21j and 21k and the coefficient g _f of the amplifiers 21p and 21q change as the listener moves forward or backward from the center, as shown by the solid line in FIG. The value to be set is set. Attenuator 21
coefficient g for j and 21k and amplifiers 21p and 21q
Intensity levels (power) of the front sound and the rear sound output from the front stereo signal speakers 3L and 3R arranged in front of _rf and g _f and the rear speakers 3SL and 3SR arranged in the rear position are shown in FIG. While the listener is in the center between the loudspeakers 3L and 3R and 3SL and 3SR, almost normal reproduction is performed. That is, the coefficient g _rf set for the attenuators 21j and 21k is almost zero, and the coefficient g _f set for the amplifiers 21p and 21q is 1.

When the listener moves rearward from the center, position information is manually input in response to the movement, or distances between the four speakers are obtained by using an infrared sensor or the like to calculate front and rear positions (not shown). By inputting the positional information to the input unit 4 by the detection means, the table conversion unit 5 adjusts the level of the front processed signal from zero with respect to the level of the rear sound (rear surround signal) in the increasing direction. set the coefficient g _rf of 21j and 21k, the coefficient g _rf attenuator 21j and 21k is a value of 2 becomes constant in the non-listening area. Then, the level of the rear surround signal is attenuated according to the increase of the level of the forward-processed signal, and 2
Adjust so that one is in balance.

As a result, as shown by the alternate long and short dash line in FIG.
And the coefficient g from the rear speaker r_fSet ahead
You can clearly hear the forward sound by adding a physical signal. one
If the listener moves forward from the center, the forward processing
The signal level becomes infinitely zero, and the amplifier 21
coefficient g of p and 21q_f Depending on the setting of
Before being output from the speakers 3L and 3R
It is adjusted so that the direction sound is not too loud. By this
As shown by the alternate long and short dash line in FIG.
The power of the forward signal output from 3R is attenuated.

Therefore, as described above, when the listener moves forward or backward from the center, the attenuators 21j and 21k and the amplifier 21 are moved according to the positional information that moves in the front-back direction.
The coefficients g _rf and g _{f of} p and 21q are set, and the sound volumes output from the speakers 3L and 3R, 3SL and 3SR are corrected. Adjusted so that the sound field can be used in a wide range.

<Fifth Embodiment> FIG. 14 is a block diagram showing a fifth embodiment of an apparatus for carrying out a multi-channel signal processing method according to another invention. In the above-described fourth embodiment, it is necessary to provide a pair of filters for performing sound image localization processing for each channel for the front stereo signals L and R, that is, four filters are used to localize the sound image at two locations. A filter is required, the scale of hardware becomes large, and it cannot be used for consumer products such as a television receiver. The fifth embodiment is effective when performing sound image localization at a position symmetrical with respect to the median plane that divides the listener's head symmetrically, and the number of filters used is the same as in the fourth embodiment shown in FIG. Half of 2
The above-mentioned problems can be solved by using the individual units.

That is, in the embodiment shown in FIG. 14, the 5-channel signals decoded and separated by the decoder 1 are arranged in symmetrical positions in front of the listener, for example, a 2-channel stereo speaker of a television receiver TV. Three
As signal processing means 2 for reproducing from L, 3R and rear speakers 3SL and 3SR arranged at rear positions, signal processing of front stereo signals L and R is performed so as to localize sound images to the rear of the listener, and the rear two channels are processed. Sound image localization circuit 2 for reproduction from the stereo speakers 3SL, 3SR
2a, an attenuator 22b for attenuating the level of the center channel signal C by 3 dB, and a center channel signal C attenuated via the attenuator 22b as a 2-channel stereo signal L,
It is provided with adders 22c and 22d for adding to R.

An amplifier 22e for correcting the levels of the front stereo signals L and R via the sound image localization circuit 22a on the basis of a coefficient g ₁ + α (= g _rf ) which is adjusted / set according to the position of the listener. And 22f and adders 22c and 2
A speaker 3 which amplifies the signal passed through 2d based on a coefficient 1-g ₁ (= g _f ) which is adjusted and set according to the position of the listener and the amplified output is arranged in the front position of the listener.
Amplifiers 22k and 22l for feeding L and 3R,
Speakers 3SL and 3SR arranged at the rear position of the listener by adding the rear surround signals SL and SR to the L and R channel signals of the front stereo signal via the amplifier 22e.
And adders 22m and 22n for supplying

Further, in the fifth embodiment shown in FIG. 14, as a means for inputting the coefficients g ₁ + α and 1-g ₁ set in the amplifiers 22e and 22f, 22k and 22l, the listener moving back and forth is used. A distance detecting means 7 for detecting the distance between the speaker and the speaker, and a position calculating / coefficient input portion 8 for calculating the position of the listener based on the detected value and inputting coefficients g ₁ + α and 1-g ₁ according to the position information. I have it.

Here, the distance detecting means 7 is not shown.
4 speakers and listeners using infrared sensors
The position calculation / coefficient input unit 8
Calculates the front-back position of the listener based on the detected value
The coefficient g according to the position information 1 + α and 1-g₁Amplifies
Input to the devices 22e and 22f, 22k and 22l. So
At this time, the position calculation / coefficient input unit 8 displays the information as shown in FIG.
The coefficient g corresponding to the front-back position of the listener._rf(= G
₁ + Α) and g_f(= 1-g₁) Related coefficient g₁ + Α
g₁ Is set, and the listener moves backward from the center.
When the amplifiers 22e and 22f have a coefficient g₁ + Α is input
Is activated, the amplifier 22k and
22l coefficient 1-g₁To be input and to operate
There is.

Further, as the sound image localization circuit 22a,
Japanese Patent Application Laid-Open No. 8-51698 proposed by the applicant of the present invention
Shuffler as shown in the publication
Use a filter. As shown in FIG. 16, the configuration of this shuffler filter has the same configuration as that of the second embodiment shown in FIG. 8 and the filter coefficients P and N shown in equations (5.1) and (5.2). The outputs of the third and fourth adders 22a ₅ and 22a ₆ are outputted as a pair of left and right filtered front stereo signals from the speakers 3SL and 3SR arranged at the rear position of the listener.

Therefore, according to the fifth embodiment,
A shuffler filter is used as the sound image localization circuit 22a for the front stereo signals L and R, processing is performed so that the sound image is localized on the left side and the right side of the listener, and the coefficient g _rf according to the position of the listener is used.
After the amplifiers 22e and 22f are adjusted and set, the rear two-channel rear surround signals SL, SR
To the front stereo signals L and R
Is output via the amplifiers 22k and 22l whose coefficient g _f is adjusted and set according to the position of the listener, so that the listener can see the sound image of 5ch while watching the television receiver TV in front. It is surrounded and the moving sound can be enjoyed, and the number of filters to be used can be reduced to two, which is half that of the fourth embodiment shown in FIG. 10, and the configuration can be simplified and the cost can be reduced. It becomes possible to incorporate it into a consumer television receiver. Also,
At that time, it is possible to adjust the sound field so that it can be used in a wide range by correcting the sound field by the stereophonic sound field according to the position of the listener.

In the description of each of the above-described embodiments, the AC-3 system developed by Dolby Laboratories is used as an example of the 5ch audio signal, but the present invention is not limited to this, and surround signals are used. It includes all signal formats divided into 2 channels of L and R.

<Sixth Embodiment> FIG. 17 is a block diagram showing a sixth embodiment of an apparatus for carrying out a multi-channel signal processing method according to another invention. Only the difference from the fifth embodiment shown in FIG. 14 will be described. In the sixth embodiment shown in FIG. 17, the rear surrounds via the amplifiers 22i and 22j in which the coefficient g _r according to the position of the listener is set. Signals SL and SR are filtered through amplifiers 22e and 22f to the front stereo signal and adders 22m and 2m.
Speaker 3S placed at the rear position by adding 2n
It is supplied to L and 3SR. That is, the amplifiers 22e and 22f relating to the front stereo signals L and R from the position detection / coefficient input unit 9 and the rear surround signal SL.
And the coefficients g ₁ and 1 of the amplifiers 22i and 22j related to SR
Defines a -g ₁ are automatically coefficients g _rf and g _r is changed while the sound volume to surrounding constant. The coefficients relating to the front speakers 3L and 3R are constant. When the distance between the front speakers 3L and 3R and the listener is sufficiently large and the distance is high, and the front sound does not feel noisy even when moving forward, the level of the front speakers is kept constant in this way. May be

<Embodiment 7> By the way, in recent years, personal computers (hereinafter referred to as PCs or personal computers) are rapidly becoming multimedia, and therefore moving images and voices are widely used on PCs. . In the seventh embodiment, as a device for carrying out the above-described multi-channel signal processing method, a case where it is carried out by a personal computer will be described with reference to the configuration diagram shown in FIG. As shown in FIG. 18, a personal computer 16 to which a surround signal processing program and a surround source are supplied via a disk drive 14 or a network (eg, Internet) terminal 15.
Is a CPU (corresponding to a controller) equipped with MMX (extended instruction set of INTEL P55C: instruction set added for efficient handling of digital signal processing such as image / sound, which is an instruction set for specific applications)
16a and RA used as a buffer during data processing
M16b, a data converter 16c for converting data input via the disk drive 14 or the network terminal 15, and an audio interface for supplying a signal processing result to a plurality of speakers 3L, 3R, 3SL and 3SR via an amplifier. 16d and.

Next, the operation of the configuration shown in FIG. 18 will be described with reference to the flowchart shown in FIG. FIG. 19
Indicates a case where a program loading command (command) is input from a keyboard (not shown) in a state where a disc on which a surround signal processing program is recorded is set in the disc drive 14, and when the program is started in this state,
In step S1, it is found that the program is loaded (when the command is input, it is determined that the program is loaded). Read program data to CPU 16a
Is supplied to the internal RAM (step S2), the program load flag is set when the program load is completed (step S3), and the process is completed. At this time, the CPU 16
Since a is compatible with MMX, signal processing can be performed at high speed.

Next, with the disc in which the surround source is recorded set in the disc drive 14, a play command is input from a keyboard (not shown), and when the program is started in this state, the program is loaded by checking the program load flag in step S1. Since it is determined that the disc is set (NO in step S1), the process proceeds to step S4, where the first track (special track) of the disc is accessed to read the subcode indicating the type of the disc, which is the surround source. J
If it is ES, the data is read from the next track in step S5, the decoding / compress / limit processing is performed, the processing data is set in the audio interface 16d (step S6), and the process returns to step S5 to perform the decoding / compression. Repeat press / limit processing. The audio interface 16d D / A converts the received data into a analog signal in a predetermined sampling period and supplies the analog signal to the speakers 3L, 3R, 3SL and 3SR. If "NO" in the step S4, "unplayable" is displayed (step S7), and the process ends.

Here, the signal processing program executed in the decoding processing in step S5 described above is composed of the processing steps shown in FIG. That is, step S31
In step S32, a multi-channel audio signal including a pair of left and right rear surround signals of the AC-3 system is decoded. In step S32, 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. By the filter processing that realizes the set convolver, the sound image localization is performed at the rear positions that are substantially symmetrical to the listener. Further, in step S33, center addition processing is performed in which the front center channel signal of the multi-channel audio signals is attenuated by a predetermined amount and added to the pair of left and right front stereo signals, and in step S34, position calculation shown in FIGS. 6 and 14 is performed. / Coefficient input section 8 (position detection / coefficient input section 9 in FIGS. 9 and 17) to coefficient g ₁ +
Read α, 1-g ₁ and set it in the attenuator. afterwards,
A left-right addition process of adding the left-right pair of rear surround signals through the filter process step S32 and the subtraction process step S34 to the left-right pair of front stereo signals to which the center channel signals have been added in step S35 is performed. Outputs obtained by passing through step S35, which are respectively localized in the rear positions that are substantially symmetrical with respect to the listener, are output to the audio interface 16d shown in FIG. 18 through output step S36.

In the AC-3 encoder, as shown in FIG. 21, the frequency of the input signal is analyzed by the filter bank 80 (for analysis), and the signal quantized by the quantizer 81 is sent to the multiplexer 82. On the other hand, the input signal is also supplied to the bit allocator 83. The output of the filter bank 80 is also fed to a spectrum envelope encoder 84.
The output of the spectrum envelope encoder 84 (differential encoding the spectrum envelope in the frequency domain) is a bit allocator 83, a core bit allocator 85, and a multiplexer 82.
Is supplied to. The output of the bit allocator 83 (sub-information for bit allocation) is supplied to the bit allocator 85 and the multiplexer 82 of the core. The output of the bit allocator of the core is supplied to the quantizer 81. The encoded bit stream is output from the multiplexer 82. With such a configuration, psychoacoustic considering auditory masking characteristics is adopted for bit allocation from the spectrum envelope to the core, and theoretically most accurate bit allocation information is calculated by the bit allocator 83 and sent to the multiplexer 82. Therefore, the multiplexer 82 can perform adaptive bit allocation with high compression efficiency.

Such a bit stream is 31.
It consists of a 25 Hz (32 ms) frame. Each frame has 16 bits of synchronization word and 8 bits of synchronization information (sy indicating the sampling frequency and frame size).
nc info), BSI (bit stream information: number of encoded channels, etc.), 6 conversion blocks (signal information), and unused data (auxiliary data)
Consists of.

As shown in FIG. 22, the step S31 for decoding the signal thus encoded is, specifically, a demultiplexer 90, a spectrum envelope decoder 91, and a dequantizer. Unit 92, core bit allocator 93, and filter bank (for synthesis) 94. The filter bank 94 has a variable resolution.

The demultiplexer 90 sets the state of the decoder from the information of the frame and decodes the signal information of the frame by the procedure shown in FIG. The original signal (multi-channel) is reproduced by the procedure reverse to such encoding.

By recording the surround signal processing program having such processing steps in a recording medium such as a disc, it is possible to easily perform signal processing of the surround source according to the surround signal processing program from the recording medium. Therefore, AC-3 compatible computer software can be provided. As described above, when the surround signal processing program and the surround source are supplied as software, the MMX compatible CP
U16a enables high-speed signal processing.

<Embodiment 8> Furthermore, as a recording medium such as a disk, a plurality of tracks are formed on the recording surface,
Moreover, each track is divided into a plurality of sectors, and a disk in which a unique address is assigned to each sector is used, and on the recording surface thereof, a first data area in which the surround signal processing program is recorded in a plurality of sectors, A TOC (TABLE) in which a surround source has a second data area recorded in a sector different from the plurality of sectors and data indicating that the recording surface has the first and second data areas
If the surround signal processing program is recorded as the first data and the surround source is recorded as the second data by providing the OF CONTENTS area, both the surround signal processing program and the surround source are recorded. AC-3 compatible computer software can be provided.

FIG. 23 is a diagram schematically showing the plane of a data recorded disc shown as a preferred embodiment of the recording medium. The disc 17 shown in FIG. 23 is, for example, an optical recording as a DVD audio disc on which an audio signal having a diameter of 120 mm is defined, which is defined by a standard disc called CD plus (System Identifiier is CD PLUS) or enhanced music CD. The medium is a first lead-in area 17a, a first data area 17b, a first lead-out area 17c, a second lead-in area 17d, a second data area 17e, and a second lead-out area 17f.
The regions are arranged in a substantially concentric pattern in this order. here,
The first lead-in area 17a is the first data area 17
The first TOC that records the address of each data in b
And the second lead-in area 17d is the second lead-in area 17d.
It constitutes a second TOC in which the address of each data in the data area 17e is recorded.

The operation by the CPU 16a shown in FIG. 18 when the disc shown in FIG. 23 is used as the recording medium will be described with reference to the flowchart shown in FIG. FIG. 23
Composite disk 17 with two data areas as shown in
When a play instruction is input from a keyboard (not shown) with the disk set in the disk drive 14, first, the flag is checked to see if the program has been loaded (step S11). The first lead-in area 17a of the inner first data area 17b shown in FIG.
The programs recorded in the first data area 17b are sequentially loaded into the internal RAM of the CPU and the program loading is continued (steps S12 to S15). If it is determined that the program is absent (step S
(YES in 13) Ends.

When the program loading is completed (YES in step S15), the test data stored after the program of the first data is read and loaded into the RAM 16b (step S16) (however, if there is not, this step is executed. Not performed). Then, the decoding program is operated to perform the test decoding process (S17). As a result, if it is judged that the data has been correctly decoded (the correct decoded signal is supplied in pairs to the test data beforehand, it is judged whether or not it is correct by comparing them). A flag indicating that the vehicle is out is set (S19), and the process returns to step S11. If "NO" in the step S18, the performance failure is displayed on the display and the process ends. AC-
Not only 3 but also surround of other standards can be applied. If YES is determined in step S11, that is, if the program has been loaded, the second data recorded in the second data area 17e is read (read), and is written as an end of file (EOF). Until that time, the same decoding process as described above is performed and output to the audio interface 16d (steps S21 to S2).
4). Then, if YES in step S22, the process ends.

[0090]

As described above, according to the multi-channel signal processing method and apparatus according to the present invention, the sound supplied to the front or the rear of the sounds reproduced by the front speaker and the rear speaker is located by the listener. In order to widen the optimum sound field range by adding stereo sound field processing to the rear speaker or the front speaker according to the above, the sound field correction by the stereo sound field is performed according to the position of the listener. The effect is that it can be adjusted so that it can be used in a wide range.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an apparatus for carrying out a multi-channel signal processing method of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement of speakers according to the present invention.

3 is a filter (ATAL-SCHR) used as a sound image localization circuit for the rear surround signals SL and SR in FIG.
It is a block diagram of an OEDER type filter).

4 is a configuration diagram of a sound image localization circuit including an ATAL-SCHROEDER filter as a component of the ATAL-SCHROEDER type filter of FIG.

5 is an explanatory diagram of coefficients and output power of the attenuator of FIG.

FIG. 6 is a configuration diagram showing a second embodiment of an apparatus for carrying out the multi-channel signal processing method of the present invention.

FIG. 7 is an explanatory diagram related to coefficients of the amplifier of FIG.

8 is a filter (shuffler filter) used as a sound image localization circuit for the rear surround signals SL and SR in FIG.
It is a block diagram of.

FIG. 9 is a configuration diagram showing a third embodiment of an apparatus for carrying out the multi-channel signal processing method of the present invention.

FIG. 10 is a configuration diagram showing a fourth embodiment of an apparatus for carrying out the multi-channel signal processing method of the present invention.

11 is a filter (ATAL-SCHROEDER) used as a sound image localization circuit for the front signals L and R in FIG.
FIG. 3 is a configuration diagram of a mold filter).

12 is an ATAL-SCHROEDE as a constituent element of the ATAL-SCHROEDER type filter of FIG.
It is a block diagram of a sound image localization circuit including an R filter.

13 is an explanatory diagram of coefficients and output powers of the attenuator and amplifier of FIG.

FIG. 14 is a configuration diagram showing a fifth embodiment of an apparatus for carrying out the multi-channel signal processing method of the present invention.

15 is an explanatory diagram related to coefficients of the amplifier of FIG. 14. FIG.

16 is a configuration diagram of a filter (shuffler filter) used as a sound image localization circuit for the front signals L and R in FIG.

FIG. 17 is a configuration diagram showing a sixth embodiment of an apparatus for carrying out the multi-channel signal processing method of the present invention.

FIG. 18 is a configuration diagram according to an embodiment in the case of being implemented by a personal computer as an apparatus for implementing the multi-channel signal processing method of the present invention.

19 is a flowchart showing the operation of the configuration shown in FIG.

FIG. 20 is a flowchart showing processing steps of a multi-channel signal processing program recorded on a recording medium.

FIG. 21 is a block diagram showing a configuration of an AC-3 encoder.

FIG. 22 is a block diagram of a configuration that realizes a step of decoding an encoded signal.

FIG. 23 is a diagram schematically showing the plane of a data recorded disc used as a recording medium.

24 is a flowchart showing an operation by the CPU 16a shown in FIG. 18 when the disc shown in FIG. 23 is used as a recording medium.

FIG. 25 is an explanatory diagram related to a relationship between a listener position and output power according to a conventional example.

[Explanation of symbols]

1 decoder 2 signal processing means 3L, 3R, 3SL, 3SR speaker 4 input section 5 table conversion section 6 coefficient setting section 7 distance detection means 8, 9 position calculation / coefficient input section 14 disk drive 15 network terminal 16a CPU 16b RAM 16d audio Interface 17 Disc (recording medium) 17a First lead-in area (TOC area) 17b First data area 17d Second lead-in area (TOC area) 17e Second data area 21a, 21d Left sound image localization filter (sound image localization means) 21b , 21c Right sound image localization filter (sound image localization means) 21e, 21j, 21k, 21n, 21o, 22b
Attenuators 21f, 21g, 21h, 21i, 21l, 21m, 2
1r, 21s, 22c, 22d, 22g, 22h, 22
m, 22n adders 21p, 21q, 22e, 22f, 22i, 22j, 2
2k, 22l amplifier 22a shuffler filter (sound image localization circuit) 22a1 first adder 22a2 second adder 22a3 first filter 22a4 second filter 22a5 third adder 22a6 adder 4 S31 AC- 3 Decoding processing step S32 Filter processing step S33 Center addition processing step S34 Left and right addition processing steps 80, 94 Filter bank 81 Quantizer 82 Multiplexer 83 Bit allocator 84 Spectrum envelope encoder 85, 93 Core bit allocator 90 Demultiplexer 91 Spectral envelope decoder 92 Dequantizer

Claims (14)

(57) [Claims] 1. A multi-channel signal including a pair of left and right front stereo signals and a rear signal is reproduced from a pair of loudspeakers arranged at a front position and a pair of loudspeakers arranged at a rear position which are substantially symmetrical to a listener. The multi-channel signal processing method according to claim 1, wherein a filtering step for outputting a pair of left and right rear processed signals that have been filtered to realize a convolver in which a filter coefficient based on a head related transfer function is set for the rear signal And an addition step of substantially adding a pair of left and right rear processed signals filtered by the filtering step to the left and right front stereo signals, and a level of the pair of left and right rear processed signals added to the front stereo signal A first level setting step for adjusting and setting Accordance with the second level setting step of adjusting and setting the level of the rear signal, multi-channel signal processing method comprising. 2. A step of supplying the output signal of the adding step to a pair of speakers arranged at the front position, and a rear signal which has been subjected to the second level setting step, to a pair of speakers arranged at the rear position. The multi-channel signal processing method according to claim 1, further comprising: 3. A position information supplying step of supplying position information of a listener, wherein the first level setting step adds the rear processed signal to the level of the stereo signal according to the position information. The multi-channel signal processing method according to claim 1 or 2, wherein the level is adjusted and set. 4. The multi-channel signal is a signal according to a predetermined standard with a 5-channel configuration of a front stereo signal of 2 channels, a center channel signal of 1 channel, and a rear signal of 2 channels, and the filtering step 4. The multi according to claim 1, further comprising a center adding step of attenuating the center channel signal and adding the center channel signal to the pair of left and right front stereo signals, between the adding step. Channel signal processing method. 5. The decoding for decoding the signal recorded on the DVD audio disc before the filtering step and the adding step, wherein the multi-channel signal is a wideband audio signal recorded on a DVD audio disc. 5. The multi-channel signal processing method according to claim 1, further comprising a processing step. 6. The filter processing step comprises filtering coefficients Hl and H1 for each channel of a pair of left and right rear signals.
r is Hl = (SF-AK) / (S 2 -A 2) Hr = (SK-AF) / (S 2 -A 2) ( however, S is from a pair of speakers to the same side of the ear of the listener A transfer function, A is a transfer function from a pair of speakers to the opposite ear of the listener, F is a transfer function from a position where a sound image is desired to be localized to the same ear of the listener, and K is a position where a sound image is desired to be localized. To the opposite ear from the listener)
On the basis of the filter processing outputs respectively set to the filter output and the filter processing output having the filter coefficient set to Hl and the filter processing output having the different filter coefficients Hr of the other channels are respectively added, and the pair of addition outputs are filtered. 6. The multi-channel signal processing method according to claim 1, wherein the processed left and right rear processed signals are output. 7. In the filtering step, the filter coefficient P is P = (F + K) / (S + A) (where S is the transfer function from a pair of speakers to the ear on the same side of the listener, and A is a pair of speakers). To the opposite ear of the listener, F is the transfer function from the position where the sound image is to be localized to the ear on the same side of the listener, and K is the opposite ear of the listener from the position where the sound image is desired to be localized. Transfer function up to)
And a first filtering output obtained by filtering the sum signal of the pair of left and right rear signals and a pair of left and right rear signals with the filter coefficient N set to N = (F−K) / (S−A) Of the first and second filtered outputs based on the second filtered output obtained by filtering the difference signal of 7. The multi-channel signal processing method according to claim 1, wherein the rear-processed signal is output. 8. A multi-channel signal including a pair of left and right front stereo signals and a rear signal is reproduced from a pair of loudspeakers arranged at a front position and a pair of loudspeakers arranged at a rear position which are substantially symmetrical to a listener. A multi-channel signal processing method according to claim 1, wherein a filter processing for outputting a pair of left and right front processed signals that have been filtered to realize a convolver in which a filter coefficient based on a head related transfer function is set for the front stereo signal A step of adding a pair of left and right front processed signals filtered by the filtering step to the left and right rear signals, and adjusting and setting levels of the pair of left and right front processed signals to be added to the rear signal A first level setting step of A second level setting step of adjusting and setting the level of the stereo signal, a multi-channel signal processing method comprising. 9. A step of supplying the output signal of the adding step to a pair of speakers arranged at the rear position, and a front stereo signal having undergone the second level setting step to a pair of speakers arranged at the front position. 9. The multi-channel signal processing method according to claim 8, further comprising: a supplying step. 10. A position information supplying step of supplying position information of a listener, wherein the first level setting step adds the front processed signal to the level of the rear signal according to the position information. 10. The multi-channel signal processing method according to claim 8, wherein the level is adjusted / set. 11. The multi-channel signal is an AC-3 system signal having a 5-channel structure of a front stereo signal of 2 channels, a center channel signal of 1 channel, and a rear signal of 2 channels, and the second level setting. 11. The method according to claim 8, further comprising, before the step, a center addition step of attenuating the center channel signal and substantially adding the center channel signal to the pair of left and right front stereo signals. Multi-channel signal processing method. 12. The multi-channel signal is a DVD
A wideband audio signal recorded on an audio disc, further comprising a decoding process step of decoding the signal recorded on the DVD audio disc before the filtering process and the adding process. 8. The multi-channel signal processing method according to any one of 8 to 11. 13. In the filtering step, filter coefficients Hl and Hr are Hl = (SF−AK) / (S ² −A ² ) Hr = (SK−AF) for each channel of a pair of left and right front stereo signals. ^{) / (S 2 -A 2)} ( however, the transfer function of the transfer function S is a pair of speakers to the same side of the ear of the listener, a is a pair of speakers to the opposite ear of the listener, F is (The transfer function from the position where the sound image is localized to the ear on the same side of the listener, K is the transfer function from the position where the sound image is localized to the ear on the opposite side of the listener)
On the basis of the filter processing outputs respectively set to the filter output and the filter processing output having the filter coefficient set to Hl and the filter processing output having the different filter coefficients Hr of the other channels are respectively added, and the pair of addition outputs are filtered. 13. The multi-channel signal processing method according to claim 8, wherein the processed left and right front stereo processed signals are output. 14. In the filtering step, a filter coefficient P is P = (F + K) / (S + A) (where S is a transfer function from a pair of speakers to an ear on the same side of a listener, and A is a pair of speakers). To the opposite ear of the listener, F is the transfer function from the position where the sound image is to be localized to the ear on the same side of the listener, and K is the opposite ear of the listener from the position where the sound image is desired to be localized. Transfer function up to)
And a first filtering output obtained by filtering the sum signal of the pair of left and right front stereo signals, and the pair of left and right fronts when the filter coefficient N is set to N = (F−K) / (S−A). A sum signal and a difference signal of the first and second filtered outputs are obtained based on a second filtered output obtained by filtering the difference signal of the stereo signal, and the sum signal and the difference signal are filtered. 13. The multi-channel signal processing method according to claim 8, wherein the left and right front stereo processed signals are output.