JP2006319803A - Digital bass booster and virtual surround decoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure an optimum S/N of an output virtual surround signal by preventing a signal level from being clipped due to bass boosting in a digital audio transmission apparatus provided with a bass boost function. <P>SOLUTION: A digital bass booster disclosed herein includes a digital level correction section and a digital bass boost section, and the digital level correction section corrects a level of an input signal in response to a bass boost amount by the digital bass boost section. The digital level correction section corrects the level of the input signal so as to prevent the signal level after bass boosting from being clipped in response to the bass boost amount by the digital bass boost section, that is, attenuates the signal level. Thus, the digital bass booster can prevent occurrence of clipping of the signal level attended with the bass boosting and perform desired bass boosting while ensuring the optimum S/N. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a virtual surround decoder device.

  In recent years, a matrix surround decoding technique has been developed to expand and reproduce a 2-channel (ch) stereo source to a multi-channel source such as 5.1 ch. A stereo sound effect can be realized by generating a multi-channel source acoustic signal from a 2ch source such as a CD by conventional stereo recording using a matrix surround decoder and performing surround reproduction.

  In general, multi-channel playback devices such as AV amplifiers and DVD players are equipped with left and right front, center, left and right from digital audio data recorded on DVD (Digital Versatile Disc) and CD (Compact Disc) recorded in multi-channel. Surround and source (sound) signals of each channel of the subwoofer are generated. Then, the multi-channel playback device outputs the multi-channel source signal to five or more speakers respectively arranged around the listener, thereby forming a realistic three-dimensional sound field.

  On the other hand, when listening to the stereophonic sound reproduced by such a multi-channel playback device through headphones, it is necessary to regenerate a 2-channel source signal by synthesizing a multi-channel source signal generated from digital audio data. . Combining multi-channel source signals with 2-channel source signals in this way is called “stereo downmix”. By playing the 2ch source signal obtained by the stereo downmix with the left and right headphones, the listener can hear the 3D sound full of realism similar to the surround system through headphones (such headphones are “surround headphones”). Is also called).

  Note that converting a multi-channel source signal into a source signal having a smaller number of channels is called “virtual surround decoding processing”, and the resulting signal is called “virtual surround signal”. The above stereo downmix is an example of a virtual surround decoding process.

  Examples of the above stereo downmix and surround headphones are described in Patent Documents 1 and 2.

  On the other hand, a bass boost device that emphasizes a low frequency component of a reproduced sound obtained by reproducing digital audio data is known (see Patent Documents 3 and 4). In addition, a technique for preventing the level of an input signal from being clipped with a bass boost process has been proposed (see, for example, Patent Document 5).

JP 2003-333699 A JP 2003-333700 A JP-A-8-288773 JP 11-330881 A Japanese Patent Laid-Open No. 11-41048

  In a bass boost device, a bass boost circuit is usually provided at a stage subsequent to a D / A converter that converts a reproduction signal into an analog signal, and bass boost processing is performed on the analog audio signal. However, when a bass boost circuit is applied to digital audio transmission equipment such as wireless headphones, it is necessary to provide a bass boost circuit on the headphone side, leading to an increase in the cost of the equipment. Also, if a bass boost circuit is provided on the headphone side, there is no change in the digital audio data transmitted from the transmission side device to the headphone, and bass boost processing is performed on the headphone side, so the transmission side device is operated. The amount of bass boost cannot be remotely controlled using a remote control.

  Examples of the problems to be solved by the present invention include the above. An object of the present invention is to prevent signal level clipping due to bass boost in a digital audio transmission device having a bass boost function, and ensure an optimum S / N.

  According to the first aspect of the present invention, the digital bass boost device includes a digital level correction unit and a digital bass boost unit, and the digital level correction unit determines the level of the input signal according to the bass boost amount by the digital bass boost unit. It is characterized by correcting.

  According to a fourth aspect of the present invention, a virtual surround decoder device includes a multichannel decoder that outputs a multichannel source signal based on an input source signal, and a digital level correction unit that corrects the level of the multichannel source signal. A virtual surround decoder that generates a virtual surround signal from the multi-channel source signal, and a digital bass boost unit that bass boosts the virtual surround signal, and the digital level correction unit includes the digital bass boost unit. The level of the source signal is corrected in accordance with the bass boost amount due to.

  According to a fifth aspect of the present invention, a virtual surround decoder device outputs a multi-channel source signal based on an input source signal and a virtual surround signal generated from the multi-channel source signal. A surround decoder; a digital bass boost unit that bass boosts the virtual surround signal; and a digital level correction unit that corrects the level of the virtual surround signal, wherein the digital level correction unit is a bass boost by the digital bass boost unit. The level of the virtual surround signal is corrected according to the amount.

  In a preferred embodiment of the present invention, the digital bass boost device includes a digital level correction unit and a digital bass boost unit, and the digital level correction unit is configured to adjust the level of the input signal according to the bass boost amount by the digital bass boost unit. Correct.

  In the above digital bass boost device, the level of the input signal is corrected according to the bass boost amount by the digital bass boost unit. If the bass boost amount is large and the signal level after bass boost is clipped as it is, level correction, that is, attenuation of the signal level is performed so that the signal level after bass boost is not clipped. Therefore, signal level clipping accompanying bass boost can be prevented, and desired bass boost can be performed while ensuring optimum S / N.

  In one preferable example of the above digital bass boost device, the digital bass boost unit is provided at a subsequent stage of the digital level correction unit. In another preferred example, the digital level correction unit is provided after the digital bass boost unit.

  In another preferred embodiment of the present invention, the virtual surround decoder device includes a multi-channel decoder that outputs a multi-channel source signal based on an input source signal, and a digital level that corrects the level of the multi-channel source signal. A correction unit; a virtual surround decoder that generates a virtual surround signal from the multi-channel source signal; and a digital bass boost unit that bass boosts the virtual surround signal, and the digital level correction unit includes the digital bus The level of the source signal is corrected according to the amount of bass boost by the boost unit.

  The virtual surround decoder device includes a multi-channel decoder that generates a multi-channel source signal from an input source signal. The input source signal can be, for example, a surround encoded stereo signal or a normal unencoded stereo signal. The multi-channel source signal includes, for example, left and right front signals, a center signal, and left and right surround signals. The level of the multi-channel source signal is corrected by the digital level correction unit.

  A virtual surround decoder arranged at the subsequent stage of the multichannel decoder generates a virtual surround signal from the source signal output from the multichannel decoder. The virtual surround decoder can be, for example, a stereo downmix processor of a Dolby headphone system, and the virtual surround signal can be, for example, a 2-channel surround headphone output signal for headphone playback.

  The virtual surround signal is subjected to bass boost processing by a digital bass boost unit. Here, the digital level correction unit corrects the level of the source signal according to the bass boost amount by the digital bass boost unit. Accordingly, it is possible to prevent the signal level from being clipped by the bass boost process, and it is possible to perform a sufficient and appropriate bass boost while ensuring the optimum S / N.

  In another embodiment of the present invention, a virtual surround decoder apparatus outputs a multi-channel source signal based on an input source signal and a virtual surround signal generated from the multi-channel source signal. A surround decoder, a digital bass boost unit that bass boosts the virtual surround signal, and a digital level correction unit that corrects the level of the virtual surround signal, wherein the digital level correction unit is a bass by the digital bass boost unit. The level of the virtual surround signal is corrected according to the boost amount.

  The virtual surround decoder device includes a matrix surround decoder that generates a multi-channel source signal from an input source signal. The input source signal can be, for example, a surround encoded stereo signal or a normal unencoded stereo signal. The multi-channel source signal includes, for example, left and right front signals, a center signal, and left and right surround signals.

  A virtual surround decoder arranged after the matrix surround decoder generates a virtual surround signal from a multi-channel source signal. The virtual surround decoder can be, for example, a stereo downmix processor of a Dolby headphone system, and the virtual surround signal can be, for example, a 2-channel surround headphone output signal for headphone playback.

  The virtual surround signal is subjected to bass boost processing by the digital bass boost unit, and the level is corrected by the digital level correction unit. Here, the digital level correction unit corrects the level of the virtual surround signal according to the bass boost amount by the digital bass boost unit. Accordingly, it is possible to prevent the signal level from being clipped by the bass boost process, and it is possible to perform a sufficient and appropriate bass boost while ensuring the optimum S / N.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 1 shows a schematic configuration of a digital audio transmission apparatus according to a first embodiment of the present invention. As illustrated, the digital audio transmission device 1 includes a transmission-side device 100 and a reception-side device 200. From the transmission side apparatus 100 to the reception side apparatus 200, digital audio data that is transmission-modulated by a predetermined method is transmitted as a transmission signal 150.

  An example of a digital audio transmission device is wireless headphones. In this case, the transmission-side device 100 is a headphone transmission unit, and the reception-side device 200 is a headphone.

  FIG. 2 is a block diagram illustrating a configuration of a virtual surround decoder device functioning as the transmission-side device 100 in the first embodiment. In FIG. 2, the virtual surround decoder device includes a digital audio interface receiver (DIR) 10, a multi-channel decoder 11, a stereo downmix processor 12, a microprocessor 13, a digital bass boost processor 14, and a D / A converter 15. A transmission modulation section 16 and a digital level correction section 18. The digital level correction unit 18 is provided in the multichannel decoder 11.

  Digital audio data D output from various audio devices as input sources is input to the DIR 10. The DIR 10 extracts the clock CK and data DT from the digital audio data D and demodulates them, and outputs the demodulated clock CK and data DT to the multi-channel decoder 11.

  The multi-channel decoder 11 includes a left front signal L, a right front signal R, a center signal C, a left surround signal Ls, a right surround signal Rs, and a subwoofer signal LFE from the data DT input from the DIR 10 in accordance with the clock CK. A 5.1 channel multi-channel signal is generated and output to the stereo downmix processor 12.

  The stereo downmix processor 12 synthesizes the left front signal L, the right front signal R, the center signal C, the left surround signal Ls, the right surround signal Rs, and the subwoofer signal LFE based on a preset downmix coefficient. As a result, 2ch surround headphone output signals Lo and Ro are generated. An example of a signal synthesis formula by a stereo downmix processor is shown below.

Lo = α (L + 0.707C + Ls + LFE)
Ro = α (R + 0.707C + Rs + LFE) (1)
Note that “α” is called an attenuation coefficient, and when the signal level of each channel simultaneously increases, the gains of the surround headphone output signals Lo and Ro exceed “1” and the reproduced sound from the headphones is clipped. It is used in order to prevent it.

  The surround headphone output signals Lo and Ro generated by the stereo downmix processor 12 are supplied to the digital bass boost processor 14. The processing by the stereo downmix processor 12 corresponds to virtual surround processing, and the surround headphone output signals Lo and Ro obtained thereby correspond to virtual surround signals.

  The digital bass boost processor 14 performs bass boost processing on the surround headphone output signals Lo and Ro based on the bass boost control signal Sc2 provided from the microprocessor 13, and outputs the processed surround headphone output signals Lob and Rob to the D / A. The voltage is supplied to the converter 15 and the transmission modulation unit 16.

  The D / A converter 15 is connected to a speaker or the like via an amplifier (not shown) and the like, and surround headphone output signals Loc and Roc are reproduced. The transmission modulation unit 16 is a modulation unit of digital audio data transmitted to the wireless headphones, and the modulated transmission signal 150 is transmitted to the reception-side device 200 such as wireless headphones. As the transmission modulation, for example, FM modulation or predetermined digital modulation can be used.

  Next, bass boost processing by the digital bass boost processor 14 and level correction by the multichannel decoder 11 will be described.

  The multichannel decoder 11 includes a digital level correction unit 18 for attenuating an internally generated multichannel signal. The level correction amount by the digital level correction unit 18, that is, the output level attenuation amount is indicated by a level correction signal Sc1 supplied from the microprocessor 13. That is, the digital level correction unit 18 attenuates the multi-channel signals L, R, C, Ls, Rs, and LFE generated in the multi-channel decoder 11 by the attenuation amount indicated by the level correction signal Sc1. After that, the data is supplied to the stereo downmix processor 12.

  On the other hand, the digital bass boost processor 14 performs bass boost processing on the surround headphone output signals Lo and Ro supplied from the stereo downmix processor 12, and outputs the processed surround headphone output signals Lob and Rob to the D / A converter. 15 and the transmission modulation unit 16. Here, the bass boost amount by the digital bass boost processor 14 is indicated by a bass boost control signal Sc2 provided from the microprocessor 13. Here, the microprocessor 13 determines the amount of attenuation by the digital level correction unit 18 so that the signal levels of the surround headphone output signals Lob and Rob after the bass boost processing by the digital bass boost processor 14 are not clipped.

  FIG. 7 shows how the signal is clipped. As shown on the left side of FIG. 7, when audio data that can be expressed by 8 bits is amplified, a portion exceeding the digital value “255” and a portion smaller than the digital value “0” The dotted line in the waveform on the right side of FIG. 7 cannot be expressed. In this way, a state in which the signal is attached to the maximum value and the minimum value is called a clip.

  The microprocessor 13 determines the level correction amount (attenuation amount) by the digital level correction unit 18 according to the bass boost amount by the digital bass boost processor 14 and supplies the bass boost control signal Sc2 to the digital bass boost processor 14. The level correction signal Sc1 is supplied to the digital level correction unit 18. As a result, the surround headphone output signals Lob and Rob output from the digital bass boost processor 14 are signals that have been subjected to sufficient and appropriate bass boost in a range where clipping does not always occur. Therefore, it is possible to prevent the occurrence of a clip caused by bass boost and to secure an optimum S / N.

  FIG. 3 shows a configuration example of the receiving side device 200. The receiving-side device 200 includes a digital audio data receiving unit 31, a digital audio data demodulating unit 32, and a D / A converter 33.

  The digital audio data receiving unit 31 receives the transmission signal 150 transmitted from the transmission side device 100 and supplies the received digital audio data DMT to the digital audio data demodulating unit 32. The digital audio data demodulator 32 demodulates the digital audio data DMT and generates a clock CK and data DT. The digital audio data demodulating unit 32 performs demodulation using a demodulation method corresponding to the modulation method used in the transmission modulation unit 16 of the receiving-side device 100.

  The D / A converter 33 converts the data DT into an analog audio signal AS using the clock CK and the data DT. The analog audio signal AS obtained in this way is used for reproduction or the like in the receiving apparatus 200. For example, when the digital audio transmission device 1 is a wireless headphone, the analog audio signal AS is reproduced by the headphone.

  As described above, according to the first embodiment, the virtual surround decoder device functioning as the transmission-side device 100 of the digital audio transmission device 1 is a multi-channel decoder that outputs a multi-channel source signal based on an input source signal. 11, a digital level correction unit 18 that corrects the level of the multi-channel source signal, a stereo downmix processor 12 that generates a surround headphone output signal from the multi-channel source signal, and a digital that bass-boosts the surround headphone output signal A bass boost processor 14. Here, the digital level correction unit 18 performs level correction of the input signal according to the bass boost amount by the digital bass boost processor 14. Accordingly, it is possible to prevent the signal level from being clipped by the bass boost process, and it is possible to perform a sufficient and appropriate bass boost while ensuring the optimum S / N.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 4 is a block diagram illustrating a configuration of a virtual surround decoder device that functions as the transmission-side device 100a of the second embodiment. In FIG. 4, the virtual surround decoder device includes a DIR 10, a matrix surround decoder 21, a stereo downmix processor 12, a microprocessor 13, a D / A converter 15, a transmission modulation unit 16, a digital bass boost processor 22, and a digital level correction unit 23. I have. Since the DIR 10, the stereo downmix processor 12, the D / A converter 15, and the transmission modulation unit 16 are the same as those in the first embodiment shown in FIG. 2, the description thereof is omitted or simplified.

  2ch digital audio data D output from various audio devices as input sources is input to the DIR 10. The DIR 10 extracts the clock CK and data DT from the digital audio data D and demodulates them, and outputs the demodulated clock CK and data DT to the matrix surround decoder 21.

  The matrix surround decoder 21 uses a matrix surround decoding technique to generate a left front signal L, a right front signal R, a center signal C, a left surround signal Ls, and a right surround signal from the 2ch data DT input from the DIR 10 according to the clock CK. A 5.1 channel multi-channel signal including Rs and subwoofer signal LFE is generated and output to the stereo downmix processor 12.

  Here, the matrix surround decoder 21 will be described in detail. FIG. 5 is a block diagram showing a configuration of a Dolby Pro Logic II decoder as an example of the matrix surround decoder 21. As shown, the matrix surround decoder 21 includes a matrix decoder 111, audio delay circuits 112L and 112R, a shelf or 7 kHz LPF 113L and 113R, a center width controller and bus management circuit 114, a volume and balance circuit 115, dimensions, A panorama and auto balance circuit 116 and a noise sequencer 117 are provided.

  The matrix decoder 111 extracts and outputs the main five-channel signals, that is, the front signals L and R, the center signal C, and the surround signals Ls and Rs from the 2-channel data DT (Lt, Rt) input from the DIR 10. To do. Specifically, the matrix decoder 111 generates a main 5-channel signal by a steering logic (direction enhancement technique) that performs matrix calculation based on the input 2ch data Lt and Rt.

  The generated front signals L and R and the center signal C are input to the center width controller and bus management circuit 114. On the other hand, the surround signals Ls and Rs are supplied to the audio delay circuits 112L and 112R, respectively. The surround signals Ls and Rs are supplied to the center width controller and the bus management circuit 114 via the audio delay circuits 112L and 112R, the shelf, or the 7 kHz LPFs 113L and 113R, respectively.

  The center width controller and bus management circuit 114 performs center width control as necessary, generates a subwoofer signal LFE, and supplies the main 5-channel signal and the subwoofer signal LFE to the volume and balance circuit 115. The volume and balance circuit 115 adjusts the volume of the signal of each channel and the balance between the signals, and outputs the signal of each channel.

  The dimension, panorama and auto balance circuit 116 is connected to the matrix decoder 111, and performs dimension control, panorama control and auto balance mode switching of the matrix decoder 111. The noise sequencer 117 outputs noise in order from the speakers of the L, C, R, Ls, and Rs channels, and adjusts the volume of the speakers of each channel and adjusts the speaker distance (that is, the delay time). This is used when making adjustments.

  The Dolby Pro Logic II decoder has a virtual mode, a prologic emulation mode and a matrix mode in addition to a movie mode suitable for playback of movie sources and general 2ch source signals, and a music mode suitable for playback of stereo music signals. Have. The functional characteristics in each mode are shown in FIG.

  In FIG. 6, “surround delay” is a delay given to the surround signals Ls and Rs by the audio delay circuits 112L and 112R, and the amount of delay differs for each mode. “Surround filter” indicates a filter process executed by a shelf or 7 kHz LPFs 113L and 113R arranged at the subsequent stage of the audio delay circuits 112L and 112R. A shelf filter is used in the music mode and the matrix mode, and a 7 kHz LPF is used in the prologic emulation mode. “Unified surround channel” is used in the movie mode, and surround speakers are in phase.

  “Panorama control” extends the stereo image of the front to the surround speakers and produces a wrapping effect by the side sound image. “Dimension control” shifts the sound field to the front side or the surround side (rear side) to adjust the level difference between the front side and the rear side. "Center width control" distributes the signal components of the center to the front left and right speakers so as not to concentrate on the center. “Auto balance” automatically controls the balance between the front left and right speakers based on the center signal C. The panorama control, dimension control and auto balance control are executed by the dimension, panorama and auto balance circuit 116 shown in FIG. Center width control is executed by the center width controller and bus management circuit 114.

  Returning to FIG. 4, as in the first embodiment, the stereo downmix processor 12 receives the left front signal L, the right front signal R, the center signal C, the left surround signal Ls, the right surround signal Rs, and the subwoofer signal LFE. By synthesizing based on a preset downmix coefficient, 2ch surround headphone output signals Lo and Ro are generated and supplied to the digital bass boost processor 22.

  The digital bass boost processor 22 performs bass boost processing on the surround headphone output signals Lo and Ro on the basis of the bass boost control signal Sc4 provided from the microprocessor 13, and outputs the processed surround headphone output signals Lob and Rob to the subsequent digital level. This is supplied to the correction unit 23.

  The digital level correction unit 23 corrects the levels of the surround headphone output signals Lob and Rob output from the digital bass boost processor 22 based on the level correction signal Sc5 provided from the microprocessor 13, and the surround headphone output signal after correction. Loc and Loc are supplied to the D / A converter 15 and the transmission modulation unit 16, respectively.

  Since the D / A converter 15 and the transmission modulation unit 16 are the same as those in the first embodiment, description thereof will be omitted. Further, the transmission signal 150 generated by the transmission modulation unit 16 is transmitted to the reception-side device 200. The receiving side apparatus 200 in the present embodiment is the same as that of the first embodiment shown in FIG.

  The microprocessor 13 acquires information on the sampling frequency (FS) included in the digital audio data D from the DIR 10, and determines the type of the input source based on the acquired information on the sampling frequency. Based on the determination result, the mode control signal Sc1 indicating one of the above-described modes (movie mode, music mode, etc.) is supplied to the matrix surround decoder 21. Further, even when the user manually selects a mode, the microprocessor 13 supplies a mode control signal Sc1 indicating the mode to the matrix surround decoder 21. The matrix surround decoder 21 performs each function described with reference to FIG. 6 based on the mode control signal Sc1.

  Further, the microprocessor 13 controls the bass boost processing by the digital bass boost processor 22 and the level correction by the multi-channel decoder. This control will be described in detail.

  As described above, the digital bass boost processor 22 performs bass boost processing on the surround headphone output signals Lo and Ro supplied from the stereo downmix processor 12, and digitally outputs the processed surround headphone output signals Lob and Rob. This is supplied to the level correction unit 23. Here, the bass boost amount by the digital bass boost processor 22 is indicated by a bass boost control signal Sc4 provided from the microprocessor 13.

  The digital level correction unit 23 performs level correction on the surround headphone output signals Lob and Rob after bass boost according to the level correction signal Sc5. Here, the microprocessor 13 determines the attenuation amount by the digital level correction unit 23 so that the signal levels of the surround headphone output signals Loc and Roc after the level correction by the digital level correction unit 23 are not clipped. That is, the microprocessor 13 determines the level correction amount (attenuation amount) by the digital level correction unit 23 according to the bass boost amount by the digital bass boost processor 22. The microprocessor 13 supplies the bass boost control signal Sc4 to the digital bass boost processor 22 and supplies the level correction signal Sc5 to the digital level correction unit 23. As a result, the surround headphone output signals Loc and Roc that are output via the digital bass boost processor 22 and the digital level correction unit 23 are signals that have been sufficiently and appropriately boosted in a range where clipping does not always occur. Therefore, it is possible to prevent the occurrence of a clip caused by bass boost and to secure an optimum S / N.

  In the example shown in FIG. 4, the digital level correction unit 23 is arranged in the subsequent stage of the digital bass boost processor 22, but the positions of both are interchanged, and the digital level correction unit 23 is arranged in the previous stage of the digital bass boost processor 22. It doesn't matter.

  As described above, the virtual surround decoder apparatus according to the second embodiment is configured to output a surround headphone output signal from the matrix surround decoder 21 that outputs a multi-channel source signal based on the input source signal and the multi-channel source signal. A stereo downmix processor 12 to be generated, a digital bass boost processor 22 for bass boosting the surround headphone output signal, and a digital level correction unit 23 for correcting the level of the surround headphone output signal are provided. Here, the digital level correction unit 23 corrects the level of the surround headphone output signal according to the bass boost amount by the digital bass boost processor 22. Accordingly, it is possible to prevent the signal level from being clipped by the bass boost process, and it is possible to perform a sufficient and appropriate bass boost while ensuring the optimum S / N.

It is a block diagram which shows schematic structure of the digital audio transmission apparatus based on the Example of this invention. It is a block diagram which shows the structure of the virtual surround decoder apparatus which functions as a transmission side apparatus by 1st Example. It is a block diagram which shows the structural example of a receiving side apparatus. It is a block diagram which shows the structure of the virtual surround decoder apparatus which functions as a transmission side apparatus by 2nd Example. It is a block diagram which shows the structure of a Dolby prologic II decoder as an example of a matrix surround decoder. It is a graph which shows the functional characteristic of the output mode of a matrix surround decoder. It is a figure which shows typically the state which the signal clipped.

Explanation of symbols

1 Digital audio transmission equipment 10 DIR
DESCRIPTION OF SYMBOLS 11 Multichannel decoder 12 Stereo downmix processor 13 Microprocessor 14, 22 Digital bus boost processor 15 D / A converter 16 Transmission modulation part 18, 23 Digital level correction part 21 Matrix surround decoder 23 Digital level correction part 31 Digital audio data reception part 32 Digital audio data demodulator 33 D / A converter 100 Transmission side device 150 Transmission signal 200 Reception side device

Claims (5)

It has a digital level correction part and a digital bass boost part.
The digital level correction unit corrects the level of an input signal according to a bass boost amount by the digital bass boost unit.   The digital bass boost device according to claim 1, wherein the digital bass boost unit is provided at a subsequent stage of the digital level correction unit.   The digital bass boost apparatus according to claim 1, wherein the digital level correction unit is provided at a subsequent stage of the digital bass boost unit. A multi-channel decoder that outputs a multi-channel source signal based on an input source signal;
A digital level correction unit for correcting the level of the multi-channel source signal;
A virtual surround decoder that generates a virtual surround signal from the multi-channel source signal;
A digital bass boost unit for bass boosting the virtual surround signal,
The virtual surround decoder device, wherein the digital level correction unit corrects the level of the source signal in accordance with a bass boost amount by the digital bass boost unit. A matrix surround decoder that outputs a multi-channel source signal based on an input source signal;
A virtual surround decoder that generates a virtual surround signal from the multi-channel source signal;
A digital bass boost unit for bass boosting the virtual surround signal;
A digital level correction unit for correcting the level of the virtual surround signal;
With
The virtual surround decoder device, wherein the digital level correction unit corrects a level of a virtual surround signal according to a bass boost amount by the digital bass boost unit.

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