JP6003680B2 - Signal correction apparatus, signal correction apparatus control method, and program - Google Patents

Description

  The present invention relates to a technical field for automatically correcting sound field characteristics in an audio system including a plurality of speakers.

  This type of technique is proposed in Patent Document 1, for example. In Patent Literature 1, by determining the same equalizer gain value (a correction parameter for adjusting the frequency characteristic by the equalizer, in other words, an equalizer coefficient) for the channels whose phases should be matched among the plurality of channels, A technique for reducing the influence of phase mismatch between channels has been proposed.

JP 2002-330499 A

  By the way, in the conventional technique, correction by an equalizer is performed for the main channel excluding the subwoofer channel. In other words, in the conventional technology, basically, the subwoofer channel is not corrected by the equalizer. Therefore, even if the phases of all channels are matched, the subwoofer channel tends to have phase characteristics different from those of other channels. For this reason, in the acoustic space (viewing environment), an ideal sound field reproduction may not be realized due to phase interference between the sub-channel signal and the other channel signal.

  The above-mentioned thing is mentioned as an example as a subject which the present invention tends to solve. An object of this invention is to provide the signal correction apparatus etc. which can correct | amend the signal of several channels including a subwoofer channel appropriately.

  In the present invention, the signal correction apparatus for correcting the audio signals of a plurality of channels including the subwoofer channel includes an equalizer that adjusts frequency characteristics of the plurality of channels, and a channel other than the subwoofer channel in the plurality of channels. A sound collection unit that outputs a detection signal corresponding to the output measurement signal; and a gain value determination unit that determines an equalizer gain value used by the equalizer to adjust a frequency characteristic based on the detection signal. The gain value determination unit determines the same value as the equalizer gain value in all of the plurality of channels.

  In the invention described in claim 1, the control method executed by the signal correction apparatus for correcting the audio signals of a plurality of channels including the subwoofer channel includes an equalizer step of adjusting frequency characteristics of the plurality of channels, and the plurality of channels. A sound collecting step for outputting a detection signal corresponding to a measurement signal output from a channel excluding the subwoofer channel, and an equalizer gain value used for adjusting a frequency characteristic in the equalizer step based on the detection signal A gain value determining step for determining the gain value, wherein the gain value determining step determines the same value as the equalizer gain value in all of the plurality of channels.

  According to another aspect of the invention, the program executed by the signal correction apparatus having a computer corrects the audio signal of a plurality of channels including the subwoofer channel, and adjusts the frequency characteristics of the plurality of channels. Equalizer means, sound collecting means for outputting a detection signal corresponding to a measurement signal output from a channel other than the subwoofer channel in the plurality of channels, and frequency characteristics in the equalizer means based on the detection signal And a gain value determining means for determining an equalizer gain value used for adjustment of the gain, wherein the gain value determining means determines the same value as the equalizer gain value in all of the plurality of channels.

It is a block diagram which shows the structure of an audio system provided with the signal correction apparatus of a present Example. It is a block diagram which shows the internal structure of the signal processing circuit shown in FIG. It is a block diagram which shows the structure of the signal processing part shown in FIG. It is a block diagram which shows the structure of the coefficient calculating part shown in FIG. FIG. 5 is a block diagram illustrating configurations of a frequency characteristic correction unit, an interchannel level correction unit, and a delay characteristic correction unit illustrated in FIG. 4. It is a figure which shows the example of arrangement | positioning of the speaker in a certain sound field environment. It is a figure for demonstrating all channel phase matching mode. 10 is a diagram for explaining a problem 3; FIG. It is a flowchart which shows an equalizer correction value setting process. It is a flowchart which shows a sound source signal reproduction | regeneration process.

  In one aspect of the present invention, a signal correction apparatus that corrects audio signals of a plurality of channels including a subwoofer channel includes an equalizer that adjusts frequency characteristics of the plurality of channels, and a channel other than the subwoofer channel in the plurality of channels. A sound collection unit that outputs a detection signal corresponding to the output measurement signal; and a gain value determination unit that determines an equalizer gain value used by the equalizer to adjust a frequency characteristic based on the detection signal. The gain value determination unit determines the same value as the equalizer gain value in all of the plurality of channels.

  According to the above signal correction apparatus, the frequency characteristics of the plurality of channels are adjusted using the same equalizer gain value in all of the plurality of channels including the subwoofer channel. Thereby, phase matching in a plurality of channels including the subwoofer channel can be realized. Therefore, the phase within the reproduction band of the subwoofer channel can be matched with other channels, and an ideal sound field space can be realized without interference such as weakening even in the acoustic space. In the present specification, the “frequency characteristic” means not a frequency phase characteristic but a frequency amplitude characteristic.

  In the above signal correction apparatus, the equalizer gain value is determined based on measurement signals output from channels other than the subwoofer channel in a plurality of channels. Due to this, playback sound that lacks low frequencies is output, or problems such as giving a load to the speaker or making strange noises by forcibly outputting a band that cannot be played back are generated. Can be suppressed appropriately.

  In one aspect of the above signal correction apparatus, the gain value determination unit is configured to apply the equalizer gain value applied to the subwoofer channel only to the reproduction frequency band of the subwoofer, and to channels other than the subwoofer channel in the plurality of channels. To the same value as the equalizer gain value applied to. Thereby, phase matching in a plurality of channels can be realized without applying an equalizer gain value to a band that is not particularly necessary for the subwoofer channel and performing equalizer correction. Further, the processing amount of the computer (DSP or the like) can be reduced, and the cost can be reduced.

  In another aspect of the signal correction apparatus, the gain value determination unit sets the equalizer gain value to “0” in the heavy bass band. As a result, it is possible to appropriately suppress problems such as a sense of incongruity in the subwoofer timbre, and problems with the subwoofer level such as a heavy bass being not output. Note that the “deep bass band” in one example corresponds to a low-frequency band in the subwoofer reproduction frequency band.

  Preferably, in the above signal correction device, the gain value determination unit determines an equalizer gain determined for the deep bass band based on the detection signal from an equalizer gain value determined for the entire band based on the detection signal. By subtracting the value, the equalizer gain value of the deep bass band can be set to “0”.

  In another aspect of the present invention, a control method executed by a signal correction apparatus that corrects audio signals of a plurality of channels including a subwoofer channel includes an equalizer step of adjusting frequency characteristics of the plurality of channels, A sound collection step for outputting a detection signal corresponding to a measurement signal output from a channel other than the subwoofer channel, and an equalizer gain value used for adjusting frequency characteristics in the equalizer step is determined based on the detection signal. A gain value determining step, wherein the gain value determining step determines the same value as the equalizer gain value in all of the plurality of channels.

  In another aspect of the present invention, a program executed by a signal correction apparatus having a computer corrects a plurality of channels of audio signals including a subwoofer channel, and adjusts the frequency characteristics of the plurality of channels. Equalizer means, sound collecting means for outputting a detection signal corresponding to a measurement signal output from a channel other than the subwoofer channel in the plurality of channels, and frequency characteristics in the equalizer means based on the detection signal The gain value determining means determines the same value as the equalizer gain value in all of the plurality of channels.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[System configuration]
Hereinafter, an embodiment of a signal correction apparatus according to the present embodiment will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of an audio system 100 including a signal correction apparatus according to the present embodiment.

  In FIG. 1, the audio system 100 includes digital audio signals SFL, SFR, SC from a sound source 1 such as a DVD (Digital Video Disc or Digital Versatile Disc), a BD (Blu-Ray Disc) player, etc. through a signal transmission path of a plurality of channels. , SSL, SSR, SWF, SSBL and SSBR are provided with a signal processing circuit 2 and a measurement signal generator 3.

  The audio system includes a signal transmission path of a plurality of channels. In the following description, each channel may be expressed as “FL channel”, “FR channel”, or the like. In addition, when referring to all of a plurality of channels in the representation of signals and components, the suffixes of reference numerals may be omitted. Further, when referring to signals and components of individual channels, subscripts for identifying the channels are attached to the reference numerals. For example, “digital audio signal S” means digital audio signals SFL to SSBR of all channels, and “digital audio signal SFL” means digital audio signals of only the FL channel. .

  Furthermore, the audio system 100 includes D / A converters 4FL to 4SBR that convert the digital outputs DFL to DSBR processed for each channel by the signal processing circuit 2 into analog signals, and these D / A converters 4FL to 4SBR. Amplifiers 5FL to 5SBR for amplifying each analog audio signal output from. The analog audio signals SPFL to SPSBR amplified by these amplifiers 5 are supplied to a plurality of speakers 6FL to 6SBR arranged in a listening room 7 as illustrated in FIG.

  The audio system 100 also includes a microphone 8 that collects the reproduced sound at the listening position RV, an amplifier 9 that amplifies the sound collection signal SM output from the microphone 8, and an output of the amplifier 9 as digital sound collection data DM. And an A / D converter 10 that converts the signal and supplies it to the signal processing circuit 2.

  Here, for the sake of convenience, the audio frequency band is an octave band of 31 Hz band to 16 kHz band (meaning a frequency width in which the ratio of the frequency between the upper limit and the lower limit centered on a predetermined frequency is one octave). To divide. A speaker 6WF dedicated to low frequency reproduction (hereinafter referred to as “subwoofer 6WF” as appropriate) reproduces heavy bass (31 Hz band) and bass (63 Hz band), and speakers 6FL, 6FR, 6C, 6SL. , 6SR reproduces an audio band of 63 Hz to 16 kHz other than heavy bass (31 Hz band). Thereby, the audio system 100 provides a sound field space with a sense of presence to the listener at the listening position RV.

  For example, as shown in FIG. 6, each speaker is arranged in accordance with ITU-R recommendation (ITU-R BS775-1), in front of the listening position RV, two front left and right channel speakers 6FL and 6FR and a center speaker. 6C is arranged. Further, surround speakers 6SL and 6SR with two channels on the left and right are arranged behind the listening position RV, and surround speakers 6SBL and 6SBR with two channels on the left and right are arranged behind them. In addition, a subwoofer 6WF dedicated to low-frequency reproduction is arranged at an arbitrary position. The signal correction device provided in the audio system 100 supplies the eight audio speakers 6FL to 6SBR with the analog audio signals SPFL to SPSBR in which the frequency characteristics, the signal level of each channel and the signal arrival delay characteristics are corrected, and causes them to ring. In order to realize a realistic sound field space.

  The signal processing circuit 2 is formed by a digital signal processor (DSP) or the like, and is roughly composed of a signal processing unit 20 and a coefficient calculation unit 30 as shown in FIG. The signal processing unit 20 receives digital audio signals of a plurality of channels from the sound source 1 that reproduces DVD, BD, and other various music sources, and performs frequency characteristic correction, level correction, and delay characteristic correction for each channel, and outputs a digital output signal DFL. ~ DSBR is output. The coefficient calculation unit 30 receives a signal collected by the microphone 8 as digital sound collection data DM, and coefficient signals SF1 to SF8, SG1 to SG8, SDL1 to SDL8 for frequency characteristic correction, level correction, and delay characteristic correction. Are respectively generated and supplied to the signal processing unit 20. Based on the sound collection data DM from the microphone 8, the signal processing unit 20 performs appropriate frequency characteristic correction, level correction, and delay characteristic correction, so that an optimum signal is output from each speaker 6.

  As shown in FIG. 3, the signal processing unit 20 includes a graphic equalizer GEQ, interchannel attenuators ATG1 to ATG8, and delay circuits DLY1 to DLY8. On the other hand, as shown in FIG. 4, the coefficient calculation unit 30 includes a system controller MPU, a frequency characteristic correction unit 11, an interchannel level correction unit 12, and a delay characteristic correction unit 13. The frequency characteristic correction unit 11, the interchannel level correction unit 12, and the delay characteristic correction unit 13 constitute a DSP.

  The frequency characteristic correction unit 11 adjusts the frequency characteristics of the equalizers EQ1 to EQ5, EQ7, and EQ8 (equalizers corresponding to channels other than the subwoofer 6WF) of the graphic equalizer GEQ. The interchannel level correction unit 12 adjusts the attenuation rate of the interchannel attenuators ATG1 to ATG8. The delay characteristic correction unit 13 adjusts the delay time of the delay circuits DLY1 to DLY8. The frequency characteristic correction unit 11, the interchannel level correction unit 12, and the delay characteristic correction unit 13 perform desired sound field correction.

  Here, for each channel other than the WF channel (subwoofer 6WF channel), the band is divided into nine bands (the center frequency of each band is f1 to f9) obtained by dividing the 63 Hz to 16 kHz band into octave bands. The coefficient of the equalizer EQ (equalizer gain value / equalizer coefficient) is determined, and the frequency characteristic is corrected. “F1 = 63 Hz”, “f2 = 125 Hz”, “f3 = 250 Hz”, “f4 = 500 Hz”, “f5 = 1 kHz”, “f6 = 2 kHz”, “f7 = 4 kHz”, “f8 = 8 kHz”, “F9 = 16 kHz”.

  The audio system 100 has two modes of operation modes: an automatic sound field correction mode and a sound source signal reproduction mode. The automatic sound field correction mode is an adjustment mode that is performed prior to signal reproduction from the sound source 1, and performs automatic sound field correction for the environment in which the system 100 is installed. Thereafter, the sound signal from the sound source 1 such as a DVD is reproduced in the sound source signal reproduction mode.

  Referring to FIG. 3, the equalizer EQ1 of the FL channel is supplied with a switch element SW12 for controlling on / off of the input of the digital audio signal SFL from the sound source 1 and an input of the measurement signal DN from the measurement signal generator 3. A switch element SW11 for on / off control is connected, and the switch element SW11 is connected to the measurement signal generator 3 via the switch element SWN.

  The switch elements SW11, SW12, and SWN are controlled by the system controller MPU formed by the microprocessor shown in FIG. 4, and when the sound source signal is reproduced, the switch element SW12 is turned on (conductive) and the switch elements SW11 and SWN are turned off (non-conductive). When the sound field is corrected, the switch element SW12 is turned off and the switch elements SW11 and SWN are turned on.

  An interchannel attenuator ATG1 is connected to the output contact of the equalizer EQ1, and a delay circuit DLY1 is connected to the output contact of the interchannel attenuator ATG1. The output DFL of the delay circuit DLY1 is supplied to the D / A converter 4FL in FIG.

  Other channels have the same configuration as the FL channel, and switch elements SW21 to SW81 corresponding to the switch element SW11 and switch elements SW22 to SW82 corresponding to the switch element SW12 are provided. Subsequently to these switch elements SW21 to SW82, equalizers EQ2 to EQ8, inter-channel attenuators ATG2 to ATG8, and delay circuits DLY2 to DLY8 are provided, and outputs DFR to DSBR of the delay circuits DLY2 to DLY8 are shown in FIG. To the D / A converters 4FR to 4SBR.

  Further, the inter-channel attenuators ATG1 to ATG8 change the attenuation rate in the range from 0 dB to the minus side in accordance with the adjustment signals SG1 to SG8 from the interchannel level correction unit 12. The delay circuits DLY1 to DLY8 of each channel change the delay time of the input signal according to the adjustment signals SDL1 to SDL8 from the phase characteristic correction unit 13.

  FIG. 5 is a block diagram illustrating the configuration of the frequency characteristic correction unit 11, the interchannel level correction unit 12, and the delay characteristic correction unit 13 illustrated in FIG.

  The frequency characteristic correction unit 11 has a function of adjusting the frequency characteristic of each channel so as to be a desired characteristic. As shown in FIG. 5A, the frequency characteristic correction unit 11 includes a bandpass filter 11a, a coefficient table 11b, a gain calculation unit 11c, a coefficient determination unit 11d, and a coefficient table 11e. The frequency characteristic correcting unit 11 corresponds to an example of a “gain value determining unit” in the present invention.

  The band pass filter 11a is composed of a plurality of narrow band digital filters that pass the nine bands set in the equalizers EQ1 to EQ8, and the sound collection data DM from the A / D converter 10 is converted to frequencies f1 to f1. By discriminating into nine frequency bands centered on f9, data [PxJ] indicating the level of each frequency band is supplied to the gain calculation unit 11c. “X” is channel numbers 1 to 8, and “J” is frequency band numbers 1 to 9. The frequency discrimination characteristic of the bandpass filter 11a is set by filter coefficient data stored in advance in the coefficient table 11b.

  The gain calculation unit 11c calculates gains (gains) of the equalizers EQ1 to EQ8 at the time of automatic sound field correction for each frequency band based on the data [PxJ] indicating the level for each band, and the calculated gain data [GxJ] Is supplied to the coefficient determination unit 11d. That is, by applying the data [PxJ] to the transfer functions of the equalizers EQ1 to EQ8 that are known in advance, the gain (gain) for each frequency band of the equalizers EQ1 to EQ8 is calculated backward.

  The coefficient determination unit 11d generates filter coefficient adjustment signals SF1 to SF8 for adjusting the frequency characteristics of the equalizers EQ1 to EQ8 under the control of the system controller MPU shown in FIG. The coefficient determination unit 11d reads out filter coefficient data for adjusting the frequency characteristics of the equalizers EQ1 to EQ8 from the coefficient table 11e using the gain data [GxJ] for each frequency band supplied from the gain calculation unit 11c, and this filter coefficient data The frequency characteristics of the equalizers EQ1 to EQ8 are adjusted by the filter coefficient adjustment signals SF1 to SF8.

  That is, filter coefficient data for variously adjusting the frequency characteristics of the equalizers EQ1 to EQ8 is stored in advance in the coefficient table 11e as a look-up table, and the coefficient determination unit 11d performs a filter corresponding to the gain data [GxJ]. The coefficient data is read, and the read filter coefficient data is supplied as filter coefficient adjustment signals SF1 to SF8 to the equalizers EQ1 to EQ8, thereby adjusting the frequency characteristics for each channel.

  The filter coefficient adjustment signal SF described above is a signal corresponding to a correction parameter used for adjusting the frequency characteristic by the equalizer EQ, and corresponds to an “equalizer gain value” (in other words, “equalizer coefficient ”). Hereinafter, the adjustment of the frequency characteristic performed by the equalizer EQ is appropriately referred to as “equalizer correction”, and the correction parameter (equalizer gain value) used for adjusting the frequency characteristic by the equalizer EQ is appropriately referred to as “equalizer correction value”. Call.

  The inter-channel level correction unit 12 has a role of making the sound pressure level of the acoustic signal output through each channel uniform. Specifically, the sound collection data DM obtained when the speakers 6FL to 6SBR are individually ringed by the measurement signal (pink noise) DN output from the measurement signal generator 3 is sequentially input, and the collection is performed. Based on the sound data DM, the level of the reproduced sound of each speaker at the listening position RV is measured.

  A schematic configuration of the inter-channel level correction unit 12 is shown in FIG. The sound collection data DM output from the A / D converter 10 is input to the level detector 12a. Note that the inter-channel level correction unit 12 basically performs level attenuation processing on the entire band of the signal of each channel, so band division is unnecessary, and therefore the frequency characteristic correction unit of FIG. 11 does not include a bandpass filter as seen in FIG.

  The level detector 12a detects the level of the sound collection data DM, and adjusts the gain so that the output audio signal level for each channel is constant. Specifically, the level detection unit 12a generates a level adjustment amount indicating a difference between the detected sound collection data level and the reference level, and outputs the level adjustment amount to the adjustment amount determination unit 12b. The adjustment amount determination unit 12b generates gain adjustment signals SG1 to SG8 corresponding to the level adjustment amounts received from the level detection unit 12a and supplies them to the inter-channel attenuators ATG1 to ATG8. Each channel attenuator ATG1 to ATG8 adjusts the attenuation rate of the audio signal of each channel according to the gain adjustment signals SG1 to SG5. By adjusting the attenuation factor of the inter-channel level correction unit 12, level adjustment (gain adjustment) between the channels is performed, and the output audio signal level of each channel becomes uniform.

  The delay characteristic correction unit 13 adjusts the signal delay caused by the distance difference between the position of each speaker and the listening position RV, that is, the output signal from each speaker 6 that should be listened to simultaneously by the listener is the listening position RV. It has a role to prevent the time to reach the time from deviating. Therefore, the delay characteristic correcting unit 13 determines the delay characteristic of each channel based on the sound collection data DM obtained when each speaker 6 is individually ringed by the measurement signal DN output from the measurement signal generator 3. Measure and correct the phase characteristics of the sound field space based on the measurement result.

  Specifically, by sequentially switching the switch elements SW11 to SW82 shown in FIG. 3, the measurement signal DN generated from the measurement signal generator 3 is output from each speaker 6 for each channel, and this is output to the microphone 8. To collect corresponding sound collection data DM. If the measurement signal is a pulse signal such as an impulse, for example, the difference between the time when the pulse signal is output from the speaker 8 and the time when the corresponding pulse signal is received by the microphone 8 is the difference between each channel. This is proportional to the distance between the speaker 6 and the microphone 8. Therefore, by combining the delay time of the remaining channels with the delay time of the channel with the largest delay amount among the delay times of each channel obtained from the measurement, the distance difference between the speaker 6 and the listening position RV of each channel is obtained. Can be absorbed. Therefore, the delay between the signals generated from the speakers 6 of each channel can be equalized, and the sounds at the same time on the time axis output from the plurality of speakers 6 reach the listening position RV at the same time.

  FIG. 5C shows the configuration of the delay characteristic correction unit. The delay amount calculation unit 13a receives the sound collection data DM, and calculates a signal delay amount due to the sound field environment for each channel based on the pulse delay amount between the pulse property measurement signal and the sound collection data. The delay amount determination unit 13b receives the signal delay amount for each channel from the delay amount calculation unit 13a and temporarily stores it in the memory 13c. With the signal delay amounts for all the channels calculated and stored in the memory 13c, the adjustment amount determination unit 13b performs other processing simultaneously with the reproduction signal of the channel having the largest signal delay amount reaching the listening position RV. The adjustment amount of each channel is determined so that the reproduction signal of the channel reaches the listening position RV, and the adjustment signals SDL1 to SDL8 are supplied to the delay circuits DLY1 to DLY8 of each channel. Each delay circuit DLY1 to DLY8 adjusts the delay amount according to the adjustment signals SDL1 to SDL8. Thus, the delay characteristic of each channel is adjusted.

[Signal correction processing]
Next, the basic principle of signal correction processing (automatic sound field correction processing) according to the present embodiment will be described. In this embodiment, various processes are performed using the “subwoofer EQ flag”, “all-channel power combining flag”, and “63 Hz band 0 dB fixed flag”. Below, the process using these flags is demonstrated concretely.

(1) Subwoofer EQ flag In this embodiment, the same equalizer correction value (equalizer gain value) is applied to all channels other than the WF channel (subwoofer 6WF channel), thereby eliminating the phase difference between the channels. A mode for realizing the sound field correction (hereinafter referred to as “all-channel phase matching mode”) is used. In the all-channel phase matching mode, the subwoofer EQ flag is set to on (sw_eq_flag = 1) so that the equalizer correction value applied to a predetermined bass band in a channel other than the WF channel is also applied to the WF channel. . That is, in the present embodiment, the equalizer correction value applied to a predetermined bass band in a channel other than the WF channel is copied to the WF channel, and the equalizer correction for the WF channel is performed.

  Thereby, phase matching in a plurality of channels including the WF channel can be realized. Therefore, the phase in the reproduction band of the WF channel can be matched with other channels, and an ideal sound field space can be realized without interference such as weakening in the acoustic space.

  The predetermined bass band is a band corresponding to the reproduction band of the subwoofer 6WF, and includes, for example, a heavy bass (31 Hz band) and a bass (63 Hz band). When the subwoofer EQ flag is off (sw_eq_flag = 0), the equalizer correction is not performed for the WF channel.

  FIG. 7 is a diagram for specifically explaining the all-channel phase matching mode according to the present embodiment. 7A and 7B show specific examples of equalizer correction values applied to each of the C channel, FL channel, FR channel, SL channel, SR channel, and WF channel. The equalizer correction value corresponds to a correction curve used in equalizer correction by the equalizer EQ, and is represented by a graph in which the horizontal axis indicates the frequency f and the vertical axis indicates the equalizer correction value gain. 7A and 7B, illustration of the SBL channel and the SBR channel is omitted for convenience of explanation.

  FIG. 7A shows a specific example of an equalizer correction value used in normal sound field correction (sound field correction performed when the all-channel phase matching mode is not set) for comparison. In normal sound field correction, an equalizer correction value is determined and applied for each channel. In normal sound field correction, no equalizer correction value is applied to the WF channel (that is, no equalizer correction is performed).

  FIG. 7B shows a specific example of the equalizer correction value used in the sound field correction performed when the all-channel phase matching mode is set. In the all-channel phase matching mode, the same equalizer correction value is determined and applied in the C channel, the FL channel, the FR channel, the SL channel, and the SR channel. In the all channel phase matching mode, the equalizer correction value is also applied to the WF channel by setting the subwoofer EQ flag to ON. Specifically, only the equalizer correction value applied to the bass band B1 in the channel other than the WF channel is copied and applied to the bass band B1 in the WF channel. For example, as the low sound band B1, a 63 Hz band, a 125 Hz band, and a 250 Hz band (that is, three low bands) are used.

  The reason why only the equalizer correction values in the 63 Hz band, the 125 Hz band and the 250 Hz band are applied to the WF channel is as follows. The configuration according to the present embodiment is assumed to be used by, for example, a high-class user who is particular about sound. Therefore, it is considered that the reproduction band setting when using the subwoofer 6WF is often set to 100 Hz or less. This is because if the frequency is set to 100 Hz or higher, the directionality of the sound is easily detected, and the sound image in the middle or lower range is affected. In view of such usage, only the equalizer correction values applied to the 63 Hz band, the 125 Hz band, and the 250 Hz band in the channels other than the WF channel are copied to the WF channel to perform the equalizer correction. As a result, all channel phase matching correction can be realized without copying and equalizing more bandwidth than necessary, and the processing amount of a computer (DSP, etc.) can be reduced, thereby reducing the cost. .

  It should be noted that the equalizer correction value is copied for the 125 Hz band and the 250 Hz band that are 100 Hz or more, and the equalizer correction is performed in consideration of the influence on the adjacent band of the equalizer EQ in addition to the reason for the operation margin. is there.

(2) All-channel power synthesis flag Also, in this embodiment, in determining the equalizer correction value for each channel in the all-channel phase matching mode, the acoustic characteristics of the channels other than the WF channel are not used intentionally. In order to use only the characteristic measurement result, the all-channel power combining flag is set to on (all_ch_pow_mix_flag = 1). In other words, in the present embodiment, in the all-channel phase matching mode, the measurement signal is simultaneously output from all the channels except the WF channel, so that the equalizer correction value as described above (equalizer correction common to the channels other than the WF channel) is obtained. Value). When the all-channel power combining flag is off (all_ch_pow_mix_flag = 0), the measurement signal is output individually from each channel without simultaneously outputting the measurement signal from all channels, so that The equalizer correction value is determined separately.

  Here, the reason why the acoustic characteristics of the WF channel are not used in determining the equalizer correction value as described above is that the following problems 1 and 2 may occur when the acoustic characteristics of the WF channel are used. That is, in this embodiment, in order to avoid the following problems 1 and 2, the equalizer correction value is determined using only the measurement result of the acoustic characteristics of channels other than the WF channel.

(Problem 1)
The configuration according to the present embodiment is assumed to be used by, for example, a high-class user who is particular about sound. Specifically, it is assumed that the speaker 6 is used by a user who uses a relatively large speaker 6 and does not use a process of sending a low-frequency signal of a channel other than the WF channel to the subwoofer 6WF. Therefore, at the time of sound source reproduction, a signal of only an LFE (Low Frequency Effect) channel is input to the WF channel and is output. Since the LFE channel is an independent channel, it is effectively used as a recording channel for the explosion sound of a movie, for example, for the producer's intention (inversely, it may be rarely used). If the frequency characteristics of all channels are corrected by using the acoustic characteristics of the WF channel as well, the correction is performed in anticipation of a corresponding sound coming from the WF channel. For this reason, during sound source reproduction, during the period when the LFE channel signal is not recorded in the sound source, a corresponding sound is not output from the WF channel, and the reproduced sound lacks the low frequency (specifically, the 63 Hz band). turn into.

(Problem 2)
Since the frequency band of the WF channel extends to the deep bass band, correction is required up to the 31 Hz band. When the all-channel phase matching mode is set in this state, the same equalizer correction value is set for all channels, so that the channels other than the WF channel are also subjected to the equalizer correction in the 31 Hz band. Therefore, when an equalizer correction value having a gain in the positive direction is set in the 31 Hz band, by trying to output the band that cannot be reproduced forcibly, a load is applied to the speaker 6 or an abnormal sound is felt. Will end up.

(3) 63 Hz Band 0 dB Fixed Flag In this embodiment, the 63 Hz band 0 dB fixed flag is turned on (63 hz_0db_fix_flag) in order to fix the 63 Hz band to 0 dB in determining the equalizer correction value of each channel in the all channel phase matching mode. = 1). That is, in this embodiment, the 63 Hz band is deliberately excluded from the frequency correction band and fixed to 0 dB. In other words, the equalizer correction value in the 63 Hz band is set to zero. When the 63 Hz band 0 dB fixed flag is off (63hz_0db_fix_flag = 0), the equalizer correction value is determined without fixing the 63 Hz band to 0 dB.

  In one example (hereinafter referred to as “first example”), as a method of determining the equalizer correction value by fixing the 63 Hz band to 0 dB, a method of determining the equalizer correction value as if there is no correction band in the 63 Hz band. Can be used. In another example (hereinafter referred to as “second example”), a method of determining the equalizer correction value by subtracting the gain of the correction band of the entire band by the necessary gain in the 63 Hz band can be used. According to the second example, there is an advantage that the level between the bands can be maintained as compared with the method of determining the equalizer correction value like the first example without the correction band in the 63 Hz band.

  On the contrary, in the second example, since the necessary gain in the 63 Hz band is subtracted from the gain of the correction band in the entire band, the equalizer parameter is affected by 63 Hz over the entire band. If a gain having a large absolute value is required at 63 Hz, a gain parameter having a large absolute value is set for the entire band. This does not satisfy the requirement of a high-end user who does not want to perform a very large equalizer correction over the entire band. In this respect, the method of the first example is advantageous, and it does not apply a very large equalizer correction over the entire band, and can satisfy the demand of a high-class user.

  Here, the reason why the 63 Hz band is fixed to 0 dB as described above is that the following problems 3 and 4 may occur unless the 63 Hz band is fixed to 0 dB. That is, in this embodiment, in order to avoid the following problems 3 and 4, the equalizer correction value is determined by performing measurement analysis with the 63 Hz band fixed to 0 dB.

(Problem 3)
The problem 3 will be described with reference to FIG. 8A and 8B show examples of frequency characteristics of channels other than the WF channel, and FIG. 8C shows an example of frequency characteristics of the WF channel. Also, a broken line A2 in FIGS. 8B and 8C shows an example of gain (gain in the positive direction) by equalizer correction applied to the 63 Hz band.

  In the channels other than the WF channel, the response is almost lost in the 31 Hz band (see the broken line area A1 in FIG. 8A). On the other hand, the WF channel generally has a higher reproduction capability in the lower band than the channels other than the WF channel, and is often reproducible up to the 31 Hz band (the broken line area in FIG. 8C). (See A4). When the equalizer correction value is copied and the equalizer correction is performed on the subwoofer 6WF that can reproduce up to the 31 Hz band without performing the process of fixing the 63 Hz band to 0 dB, there is a relatively large level difference between the 31 Hz band and the 63 Hz band. (See arrow A3 in FIG. 8C). In that case, a change in level difference may be recognized, which may cause a sense of incongruity in the timbre of the subwoofer 6WF. On the other hand, in the channels other than the WF channel, the 31 Hz band is not so much originally output, so even if the equalizer correction is performed on the 63 Hz band, there is almost no comparison target of the 31 Hz band, and such a sense of incongruity does not occur (FIG. 8B )reference).

  As described above, in the subwoofer 6WF, the 31 Hz band is sufficiently reproduced. Therefore, if equalizer correction is performed for the 63 Hz band, a problem in hearing may occur.

(Problem 4)
Generally, the level of the WF channel is adjusted by reproducing pink noise and measuring the level. However, as described above, a relatively large level difference occurs between the 31 Hz band and the 63 Hz band. In this case, measurement is performed with a priority on a relatively large band. For this reason, the volume is adjusted to have no problem in a band with a high level, but the volume that can be heard is small in a band with a low level because of the difference. For example, problems such as a heavy bass being not output may occur.

[Processing flow]
Next, the processing flow performed in the present embodiment will be described with reference to FIGS.

  FIG. 9 is a flowchart showing the equalizer correction value setting process. This flow is executed in the signal processing circuit 2. This flow is executed when the above-described automatic sound field correction mode is set.

  First, in step S11, it is determined whether or not the all-channel phase matching mode is set. In this case, the determination is performed based on an instruction from the system controller MPU. For example, the all-channel phase matching mode is set by user selection.

  When the all-channel phase matching mode is set (step S11: Yes), in step S12, the all-channel power combining flag is set on (all_ch_pow_mix_flag = 1), and the 63 Hz band 0 dB fixed flag is set on. (63hz_0db_fix_flag = 1). Then, the process proceeds to step S14. On the other hand, when the all-channel phase matching mode is not set (step S11: No), the all-channel power combining flag is set to OFF (all_ch_pow_mix_flag = 0) and the 63 Hz band 0 dB fixed flag is set in step S13. Is set to off (63hz_0db_fix_flag = 0). Then, the process proceeds to step S14.

  In step S14, the equalizer correction value is calculated according to the flag set in step S12 or step S13. Specifically, when the all-channel phase matching mode is set, the all-channel power combining flag is set to ON and the 63 Hz band 0 dB fixed flag is set to ON. A value is calculated. First, in the signal processing unit 20, the switch element SWN is set to ON, the switch elements SW11 to SW51, SW71, and SW81 are set to ON (the switch element SW61 is set to OFF), and the switch elements SW12 to SW82 are set to OFF. By setting, the measurement signal DN is simultaneously output from all channels except the WF channel, collected by the microphone 8, and input to the signal processing circuit 2 as the sound collection data DM. Then, the frequency characteristic correction unit 11 in the coefficient calculation unit 30 calculates an equalizer correction value for adjusting the characteristic of the equalizer EQ based on the sound collection data DM. In this case, the frequency characteristic correction unit 11 calculates the equalizer correction value while fixing the 63 Hz band to 0 dB. As a method of fixing the 63 Hz band to 0 dB, the method exemplified in the section “(3) 63 Hz band 0 dB fixed flag” can be applied. In addition, before calculating the equalizer correction value as described above, it is preferable to perform the inter-channel level correction process on all channels except the WF channel so that the levels of all the channels are matched.

  On the other hand, when the all-channel phase matching mode is not set, the all-channel power combining flag is set to OFF and the 63 Hz band 0 dB fixed flag is set to OFF. Calculated. In this case, the equalizer correction value is calculated individually for each channel by outputting the measurement signal DN sequentially from each channel. Specifically, first, the signal processing unit 20 sets the switch element SWN to ON, sets the switch element SW11 to ON, and sets the switch elements SW21 to SW81 and the switch elements SW12 to SW82 to OFF. The measurement signal DN is output only from the FL channel, and the microphone 8 collects the signal and inputs the sound collection data DM to the signal processing circuit 2. Then, the frequency characteristic correction unit 11 in the coefficient calculation unit 30 calculates an equalizer correction value for adjusting the characteristic of the equalizer EQ1 corresponding to the FL channel, based on the sound collection data DM. Thereafter, the frequency characteristic correction unit 11 sequentially calculates the equalizer correction value for each channel until the equalizer correction value is calculated for all channels except the WF channel. When the all-channel phase matching mode is not set (that is, when the 63 Hz band 0 dB fixed flag is off), the frequency characteristic correction unit 11 calculates the equalizer correction value without fixing the 63 Hz band to 0 dB. To do.

  Equalizer correction is performed by the equalizer EQ according to the equalizer correction value calculated as described above. In the audio system 100, as the automatic sound field correction process, in addition to the equalizer correction value setting process (in other words, the frequency characteristic correction process) shown in FIG. 9, an inter-channel level correction process, a delay characteristic correction process, and the like are performed. However, description of these will be omitted.

  FIG. 10 is a flowchart showing the sound source signal reproduction process. This flow is executed in the signal processing circuit 2. This flow is executed when the above-described sound source signal reproduction mode is set.

  First, in step S21, it is determined whether or not the all-channel phase matching mode is set. In this case, the determination is performed based on an instruction from the system controller MPU.

  When the all-channel phase matching mode is set (step S21: Yes), the subwoofer EQ flag is set to on (sw_eq_flag = 1) in step S22. Then, the process proceeds to step S24. On the other hand, when the all-channel phase matching mode is not set (step S21: No), the subwoofer EQ flag is set to OFF in step S23 (sw_eq_flag = 0). Then, the process proceeds to step S24.

  In step S24, the signal processing unit 20 in the signal processing circuit 2 performs a process for reproducing the signal from the sound source 1 according to the flag set in step S22 or step S23. Specifically, the signal processing unit 20 receives digital audio signals of a plurality of channels from the sound source 1 that reproduces DVD, BD, and other various music sources, and performs frequency characteristic correction, level correction, and delay characteristic correction for each channel. Digital output signals DFL to DSBR. In this case, the switch elements SW12 to SW82 are set to ON, and the switch element SWN and the switch elements SW11 to SW81 are set to OFF.

  More specifically, when the all-channel phase matching mode is set, that is, when the subwoofer EQ flag is on, the signal processing unit 20 uses the same equalizer correction value for channels other than the WF channel. (Equalizer correction value determined in the flow of FIG. 9) is performed, and for the WF channel, the equalizer correction value applied to the 63 Hz band, the 125 Hz band, and the 250 Hz band is copied in the channel other than the WF channel. Make corrections. On the other hand, when the all-channel phase matching mode is not set, that is, when the subwoofer EQ flag is off, the signal processing unit 20 determines the equalizer determined for each channel for channels other than the WF channel. Equalizer correction is performed using the correction value (equalizer correction value determined in the flow of FIG. 9), and no equalizer correction is performed for the WF channel.

[Modification]
In the above-described embodiment, only the equalizer correction value applied to a predetermined bass band (63 Hz band, 125 Hz band, and 250 Hz band) in a channel other than the WF channel is applied to the WF channel. All equalizer correction values applied to the entire frequency band (that is, the audio band of 63 Hz to 16 kHz) may be applied to the WF channel. That is, the same equalizer correction value may be used for all channels including the WF channel in all frequency bands.

  In the above-described embodiment, the equalizer correction value applied to the 63 Hz band, the 125 Hz band, and the 250 Hz band in the channels other than the WF channel is applied to the WF channel. However, the equalizer correction value is applied to the WF channel. There is no limitation to using the 63 Hz band, the 125 Hz band, and the 250 Hz band. For example, an equalizer correction value applied to a channel other than the WF channel is applied to the WF channel using various bands corresponding to reproduction bands of various subwoofers or a minimum band that can be output by a channel other than the subwoofer. It can be used as a band.

  In the above-described embodiment, the 63 Hz band is fixed to 0 dB. However, the use of the 63 Hz band is not limited as the band to be fixed to 0 dB. For example, various bands according to a reproduction band possessed by various subwoofers and a minimum band that can be output by a channel other than the subwoofer can be used as a band to be fixed at 0 dB.

  In another example of the above-described embodiment, correction can be performed by a linear phase filter. In that case, after the automatic sound field is measured and the correction parameter is determined as usual, the above-described equalizer may be converted into a linear phase filter and the correction may be executed. As a result, if the filter is an all-channel linear phase filter, the target all-channel in-phase can be realized without applying an equalizer to the subwoofer.

[Application example]
The present invention can be applied to, for example, an AV receiver and a home theater system.

DESCRIPTION OF SYMBOLS 1 Sound source 2 Signal processing circuit 3 Signal generator for measurement 6 Speaker 8 Microphone 9 Amplifier 10 A / D converter 11 Frequency characteristic correction part 12 Channel level correction part 13 Delay characteristic correction part ATG1-ATG8 Channel attenuator DLY1-DLY8 Delay Circuit EQ1 to EQ8 Equalizer GEQ Graphic equalizer MPU System controller SW11 to SW82, SWN Switch element

Claims (4)

A signal correction apparatus for correcting audio signals of a plurality of channels including a subwoofer channel,
An equalizer for adjusting frequency characteristics of the plurality of channels;
A sound collection unit that outputs a detection signal corresponding to a measurement signal output from a channel other than the subwoofer channel in the plurality of channels;
Based on the detection signal, a gain value determination unit that determines an equalizer gain value that the equalizer uses to adjust frequency characteristics;
With
The gain correction unit determines a same value as the equalizer gain value in all of the plurality of channels.   For the equalizer gain value applied to the subwoofer channel, only the reproduction frequency band of the subwoofer is the same value as the equalizer gain value applied to a channel other than the subwoofer channel in the plurality of channels. The signal correction apparatus according to claim 1, wherein: A control method executed by a signal correction device for correcting audio signals of a plurality of channels including a subwoofer channel,
  An equalizer step of adjusting the frequency characteristics of the plurality of channels;
  A sound collection step of outputting a detection signal corresponding to a measurement signal output from a channel other than the subwoofer channel in the plurality of channels;
  Based on the detection signal, a gain value determining step for determining an equalizer gain value used for adjusting frequency characteristics in the equalizer step;
With
  The gain value determining step determines the same value as the equalizer gain value in all of the plurality of channels.   A program executed by a signal correction apparatus having a computer and correcting audio signals of a plurality of channels including a subwoofer channel,
  The computer,
  Equalizer means for adjusting frequency characteristics of the plurality of channels;
  Sound collecting means for outputting a detection signal corresponding to a measurement signal output from a channel other than the subwoofer channel in the plurality of channels;
  Based on the detection signal, gain value determining means for determining an equalizer gain value used for adjusting frequency characteristics in the equalizer means;
Function as
  The gain value determining means determines the same value as the equalizer gain value in all of the plurality of channels.

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