Abstract:
An audio processing apparatus comprising: channel determination section for determining which one of a combination of the first left audio signal and the first right audio signal and a combination of the second left audio signal and the second right audio signal is included in multichannel audio data; and switching section for causing the first amplification section to amplify the first left audio signal and supply the amplified first left audio signal to the first speaker terminal and causing the second amplification section to amplify the first right audio signal and supply the amplified first right audio signal to the second speaker terminal when the combination of the first left audio signal and the first right audio signal is determined to be included; and causing the first amplification section to amplify the second left audio signal and supply the amplified second left audio signal to the third speaker terminal and causing the second amplification section to amplify the second right audio signal and supply the amplified second right audio signal to the fourth speaker terminal when the combination of the second left audio signal and the second right audio signal is determined to be included.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an audio processing apparatus that plays back multichannel audio data including an upper left audio signal, an upper right audio signal, an outer left audio signal, and an outer right audio signal. 
     2. Description of the Related Art 
     An audio playback system including a BD player, an AV amplifier, and a display apparatus has been used. Audio data transmitted from the BD player to the AV amplifier is obtained by encoding multichannel audio data. For example, the multichannel audio data includes, as shown in  FIG. 3 , a left audio signal L, a right audio signal R, a center audio signal C, a low-frequency audio signal SW, a surround left audio signal SL, a surround right audio signal SR, a surround back left audio signal SBL, and a surround back right audio signal SBR. Recently, HD (High Definition) related audio formats such as Dolby True HD, Dolby Digital Plus, and DTS-HD have appeared. In these formats, an upper left audio signal LH, an upper right audio signal RH, an outer left audio signal LW, and an outer right audio signal RW are further added. 
     However, when amplifiers associated with audio signals of all these channels are provided to the AV amplifier, amplifiers for 11.1 channels in total are to be provided, resulting in very high cost. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is therefore to provide an audio processing apparatus capable of amplifying audio signals, such as an upper left audio signal LH, an upper right audio signal RH, an outer left audio signal LW, and an outer right audio signal RW, and outputting the amplified audio signals from speaker terminals associated with these channels, without the need to provide amplifiers of the same number as all channels. 
     According to a preferred embodiment of the present invention, an audio processing apparatus comprising: first amplification section for amplifying an outer left audio signal or an upper left audio signal; second amplification section for amplifying an outer right audio signal or an upper right audio signal; a first speaker terminal that outputs the outer left audio signal; a second speaker terminal that outputs the outer right audio signal; a third speaker terminal that outputs the upper left audio signal; a fourth speaker terminal that outputs the upper right audio signal; channel determination section for determining which one of a combination of the outer left audio signal and the outer right audio signal and a combination of the upper left audio signal and the upper right audio signal is included in multichannel audio data; and switching section for causing the first amplification section to amplify the outer left audio signal and supply the amplified outer left audio signal to the first speaker terminal and causing the second amplification section to amplify the outer right audio signal and supply the amplified outer right audio signal to the second speaker terminal when the combination of the outer left audio signal and the outer right audio signal is determined to be included; and causing the first amplification section to amplify the upper left audio signal and supply the amplified upper left audio signal to the third speaker terminal and causing the second amplification section to amplify the upper right audio signal and supply the amplified upper right audio signal to the fourth speaker terminal when the combination of the upper left audio signal and the upper right audio signal is determined to be included. 
     A determination as to which channel combination is included in multichannel audio data is made and the included channel combination is amplified by the first amplification section and the second amplification section. By this, only by providing two amplification section, a combination of an outer left audio signal and an outer right audio signal or a combination of an upper left audio signal and an upper right audio signal can be amplified and the amplified audio signals can be outputted to speaker terminals associated with channels of the audio signals. 
     Preferably, the audio processing apparatus further comprising: a fifth speaker terminal that outputs a surround back left audio signal; and a sixth speaker terminal that outputs a surround back right audio signal, wherein the channel determination section determines which one of a combination of the outer left audio signal and the outer right audio signal, a combination of the upper left audio signal and the upper right audio signal, and a combination of the surround back left audio signal and the surround back right audio signal is included in multichannel audio data, and when the combination of the outer left audio signal and the outer right audio signal is determined to be included, the switching section causes the first amplification section to amplify the outer left audio signal and supply the amplified outer left audio signal to the first speaker terminal and causes the second amplification section to amplify the outer right audio signal and supply the amplified outer right audio signal to the second speaker terminal; when the combination of the upper left audio signal and the upper right audio signal is determined to be included, the switching section causes the first amplification section to amplify the upper left audio signal and supply the amplified upper left audio signal to the third speaker terminal and causes the second amplification section to amplify the upper right audio signal and supply the amplified upper right audio signal to the fourth speaker terminal; and when the combination of the surround back left audio signal and the surround back right audio signal is determined to be included, the switching section causes the first amplification section to amplify the surround back left audio signal and supply the amplified surround back left audio signal to the fifth speaker terminal and causes the second amplification section to amplify the surround back right audio signal and supply the amplified surround back right audio signal to the sixth speaker terminal. 
     A determination as to which channel combination is included in multichannel audio data is made and the included channel combination is amplified by the first amplification section and the second amplification section. By this, only by providing two amplification section, a combination of an outer left audio signal and an outer right audio signal, a combination of an upper left audio signal and an upper right audio signal, or a combination of a surround back left audio signal and a surround back right audio signal can be amplified and the amplified audio signals can be outputted to speaker terminals associated with channels of the audio signals. 
     According to another preferred embodiment of the present invention, an audio processing apparatus comprising: first amplification section for amplifying a first left audio signal or a second left audio signal; second amplification section for amplifying a first right audio signal or a second right audio signal; a first speaker terminal that outputs the first left audio signal; a second speaker terminal that outputs the first right audio signal; a third speaker terminal that outputs the second left audio signal; a fourth speaker terminal that outputs the second right audio signal; channel determination section for determining which one of a combination of the first left audio signal and the first right audio signal and a combination of the second left audio signal and the second right audio signal is included in multichannel audio data; and switching section for causing the first amplification section to amplify the first left audio signal and supply the amplified first left audio signal to the first speaker terminal and causing the second amplification section to amplify the first right audio signal and supply the amplified first right audio signal to the second speaker terminal when the combination of the first left audio signal and the first right audio signal is determined to be included; and causing the first amplification section to amplify the second left audio signal and supply the amplified second left audio signal to the third speaker terminal and causing the second amplification section to amplify the second right audio signal and supply the amplified second right audio signal to the fourth speaker terminal when the combination of the second left audio signal and the second right audio signal is determined to be included. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an arrangement of an AV amplifier  1  and speakers; 
         FIG. 2  is a diagram showing an audio playback system; 
         FIG. 3  is a diagram showing channels of audio signals; 
         FIG. 4  is a diagram showing an audio processing unit  5 ; 
         FIG. 5  is a flowchart showing a process performed by a control unit  2 ; 
         FIG. 6  is a diagram showing an audio processing unit  5 B; 
         FIG. 7  is a flowchart showing a process performed by the control unit  2 ; 
         FIG. 8  is a diagram showing an audio processing unit  5 C; and 
         FIG. 9  is a diagram showing an audio processing unit  5 D. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Audio playback systems including a disc playback apparatus (hereinafter, referred to as the BD player), an audio processing apparatus (hereinafter, referred to as the AV amplifier), and a display apparatus, according to preferred embodiments of the present invention will be specifically described below with reference to the drawings but the present invention is not limited thereto. 
       FIG. 1  is a diagram showing an example of an arrangement of an AV amplifier  1  and speakers. To the AV amplifier  1  are connected a left speaker SL, a right speaker SR, a center speaker SC, a low-frequency speaker SSW, a surround left speaker SSL, a surround right speaker SSR, a surround back left speaker SSBL, a surround back right speaker SSBR, an upper left speaker SLH, an upper right speaker SRH, an outer left speaker SLW, and an outer right speaker SRW. 
       FIG. 2  is a block diagram showing a configuration of an audio playback system. A BD player  100 , an AV amplifier  1 , and a display apparatus  200  conform to the HDMI standard, for example, and are connected to each other via HDMI cables. The BD player  100  transmits HDMI data including multichannel audio data and video data to the AV amplifier  1 . The AV amplifier  1  amplifies the multichannel audio data included in the HDMI data received from the BD player  100  and outputs the amplified multichannel audio data to speakers. Also, the AV amplifier  1  transmits the HDMI data including video data to the display apparatus  200 . The display apparatus  200  displays the video data included in the HDMI data received from the AV amplifier  1 . 
     The AV amplifier  1  has a control unit  2 , an HDMI receiving unit  3 , an HDMI transmitting unit  4 , an audio processing unit  5 , an operation unit  6 , a display unit  7 , and HDMI terminals  8  and  9 . To the AV amplifier  1  are connected speakers  300  (corresponding to the speakers in  FIG. 1 ). 
     The HDMI receiving unit  3  receives HDMI data transmitted from the BD player  100 , generates original video data from the received HDMI data, and supplies the video data to the HDMI transmitting unit  4 . Also, the HDMI receiving unit  3  generates original multichannel audio data from the received HDMI data and supplies the multichannel audio data to the audio processing unit  5 . 
     The audio processing unit  5  decodes the multichannel audio data supplied from the HDMI receiving unit  3 , performs processes including an acoustic process, a D/A conversion process, a volume control process, an amplification process, and the like, on the decoded multichannel audio data, and supplies audio signals of various channels to the speakers  300 . 
     Multichannel audio data to be supplied to the audio processing unit  5  will be described. In HD (High Definition) related audio formats such as Dolby True HD, Dolby Digital Plus, and DTS-HD, as shown in  FIG. 3 , there are, for example, a left audio signal L (front left audio signal), a right audio signal R (front right audio signal), a center audio signal C, a low-frequency audio signal SW, a surround left audio signal SL, a surround right audio signal SR, a surround back left audio signal SBL, a surround back right audio signal SBR, an outer left audio signal LW (first left audio signal), an outer right audio signal RW (first right audio signal), an upper left audio signal LH (second left audio signal), an upper right audio signal RH (second right audio signal), and the like. 
     The upper left audio signal LH is an audio signal played back from a position on the upper side of the left audio signal L (i.e., the front upper left side of a user). The upper right audio signal RH is an audio signal played back from a position on the upper side of the right audio signal R (i.e., the front upper right side of the user). The outer left audio signal LW is an audio signal played back from a position on the outer side (left side) of the left audio signal L (i.e., the front outer left side of the user). The outer right audio signal RW is an audio signal played back from a position on the outer side (right side) of the right audio signal R (i.e., the front outer right of the user). 
       FIG. 4  is a block diagram showing the main part of the audio processing unit  5 . The audio processing unit  5  has a pre-out unit  11 , power amplifiers  12 , an SP (speaker) relay  13 , and SP (speaker) terminals  14 . In  FIG. 4 , circuits for basic 5.1 channels (a left audio signal L, a right audio signal R, a center audio signal C, a low-frequency audio signal SW, a surround left audio signal SL, and a surround right audio signal SR) are the same as those in conventional art and thus are not shown. A DSP and the like provided in a previous stage to the pre-out unit  11  are not shown, either. 
     The DSP decodes and D/A converts multichannel audio data supplied from the HDMI receiving unit  3  and thereby generates audio signals of various channels. The generated audio signals are supplied to the pre-out unit  11 . 
     The pre-out unit  11  includes switches S 11   a  to S 11   f . The switch S 11   a  switches whether to output a surround back left audio signal SBL to an amplifier  12   a . The switch S 11   b  switches whether to output an upper left audio signal LH to the amplifier  12   a . The switch S 11   c  switches whether to output an outer left audio signal LW to the amplifier  12   a . Any one of the switches S 11   a  to S 11   c  is brought into an on state and any one of the surround back left audio signal SBL, the upper left audio signal LH, and the outer left audio signal LW is supplied to the amplifier  12   a.    
     The switch S 11   d  switches whether to output a surround back right audio signal SBR to an amplifier  12   b . The switch S 11   e  switches whether to output an upper right audio signal RH to the amplifier  12   b . The switch S 11   f  switches whether to output an outer right audio signal RW to the amplifier  12   b . Any one of the switches S 11   d  to S 11   f  is brought into an on state and any one of the surround back right audio signal SBR, the upper right audio signal RH, and the outer right audio signal RW is supplied to the amplifier  12   b.    
     The power amplifiers  12  include the amplifiers  12   a  and  12   b . The amplifier  12   a  amplifies the surround back left audio signal SBL, the upper left audio signal LH, or the outer left audio signal LW inputted thereto and supplies the amplified audio signal to the SP relay  13  (a switch S 13   a , S 13   c , or S 13   e ). The amplifier  12   b  amplifies the surround back right audio signal SBR, the upper right audio signal RH, or the outer right audio signal RW inputted thereto and supplies the amplified audio signal to the SP relay  13  (a switch S 13   b , S 13   d , or S 13   f ). 
     The SP relay  13  has the relay switches (hereinafter, referred to as the switches) S 13   a  to S 13   f . The switch S 13   a  switches whether to supply the surround back left audio signal SBL inputted from the amplifier  12   a , to a surround back left SP terminal  14   a . The switch S 13   a  is brought into an on state when the switch S 11   a  is in an on state. The switch S 13   c  switches whether to supply the upper left audio signal LH inputted from the amplifier  12   a , to an upper left SP terminal  14   c . The switch S 13   c  is brought into an on state when the switch S 11   b  is in an on state. The switch S 13   e  switches whether to supply the outer left audio signal LW inputted from the amplifier  12   a , to an outer left SP terminal  14   e . The switch S 13   e  is brought into an on state when the switch S 11   c  is in an on state. 
     The switch S 13   b  switches whether to supply the surround back right audio signal SBR inputted from the amplifier  12   b , to a surround back right SP terminal  14   b . The switch S 13   b  is brought into an on state when the switch S 11   d  is in an on state. The switch S 13   d  switches whether to supply the outer right audio signal RH inputted from the amplifier  12   b , to an upper right SP terminal  14   d . The switch S 13   d  is brought into an on state when the switch S 11   e  is in an on state. The switch S 13   f  switches whether to supply the outer right audio signal RW inputted from the amplifier  12   b , to an outer right SP terminal  14   f . The switch S 13   f  is brought into an on state when the switch S 11   f  is in an on state. 
     The SP terminals  14  include the SP terminals  14   a  to  14   f . The surround back left speaker SSBL is connected to the surround back left SP terminal  14   a , the surround back right speaker SSBR is connected to the surround back right SP terminal  14   b , the upper left speaker SLH is connected to the upper left SP terminal  14   c , the upper right speaker SRH is connected to the upper right SP terminal  14   d , the outer left speaker SLW is connected to the outer left SP terminal  14   e , and the outer right speaker SRW is connected to the outer right SP terminal  14   f.    
     Returning to  FIG. 2 , the HDMI transmitting unit  4  converts the video data supplied from the HDMI receiving unit  3  to HDMI data and transmits the HDMI data to the display apparatus  200 . 
     The control unit  2  controls each unit based on an operating program of the AV amplifier  1  stored in a memory (not shown) built therein or connected thereto. The control unit  2  is, for example, a microcomputer or CPU. 
     The control unit  2  performs control to switch between the switches S 11   a  to S 11   f  and S 13   a  to S 13   f  (a detail of which will be described later). 
     The display unit  7  displays images showing the SP terminals  14   a  to  14   f  and the channels and functions of audio signals assigned to the SP terminals  14   a  to  14   f  (a detail of which will be described later). 
       FIG. 5  is a flowchart showing a process performed by the control unit  2 . The HDMI receiving unit  3  generates original multichannel audio data from HDMI data and supplies the multichannel audio data to the audio processing unit  5 . The audio processing unit  5  decodes the multichannel audio data, reads channel information included in an information area of the multichannel audio data, and supplies the channel information to the control unit  2 . 
     The control unit  2  determines whether a determination as to whether which one of a combination of the surround back left audio signal SBL and the surround back right audio signal SBR, a combination of the upper left audio signal LH and the upper right audio signal RH, and a combination of the outer left audio signal LW and the outer right audio signal RW is supplied to corresponding SP terminals is uniquely made by a listening mode selected by a user operation (S 1 ). If the determination is uniquely made (YES in S 1 ), then the control unit  2  controls the switches S 11   a  to S 11   f  and S 13   a  to S 13   f  to supply a combination to be determined to corresponding SP terminals (S 2 ). 
     If the determination is not uniquely made (NO in S 1 ), then the control unit  2  determines whether in the listening mode selected by the user operation a channel combination to be supplied to SP terminals is determined by a user operation (S 3 ). If a channel combination is thus determined (YES in S 3 ), then the control unit  2  controls the switches S 11   a  to S 11   f  and S 13   a  to S 13   f  to supply a channel combination to be determined to corresponding SP terminals (S 4 , S 5 , and S 8  to S 10 ). 
     If a channel combination is not thus determined (NO in S 3 ), then the control unit  2  determines which one of a combination of the surround back left audio signal SBL and the surround back right audio signal SBR, a combination of the upper left audio signal LH and the upper right audio signal RH, and a combination of the outer left audio signal LW and the outer right audio signal RW is included, based on the channel information of input signals included in the multichannel audio data supplied from the audio processing unit  5  (S 6 , S 7 , and S 11 ). 
     If a combination of the outer left audio signal LW and the outer right audio signal RW is included in the multichannel audio data (YES in S 6 ), then the control unit  2  controls the switches to supply the outer left audio signal LW to the outer left SP terminal  14   e  and supply the outer right audio signal RW to the outer right SP terminal  14   f  (S 8 ). Specifically, the control unit  2  controls the switches S 11   c , S 11   f , S 13   e , and S 13   f  to be an on state and other switches to be an off state. 
     If a combination of the upper left audio signal LH and the upper right audio signal RH is included in the multichannel audio data (NO in S 6  and YES in S 7 ), then the control unit  2  controls the switches to supply the upper left audio signal LH to the upper left SP terminal  14   c  and supply the upper right audio signal RH to the upper right SP terminal  14   d  (S 9 ). Specifically, the control unit  2  controls the switches S 11   b , S 11   e , S 13   c , and S 13   d  to be an on state and other switches to be an off state. 
     If a combination of the surround back left audio signal SBL and the surround back right audio signal SBR is included in the multichannel audio data (NO in S 6 , NO in S 7 , and YES in S 11 ), then the control unit  2  controls the switches to supply the surround back left audio signal SBL to the surround back left SP terminal  14   a  and supply the surround back right audio signal SBR to the surround back right SP terminal  14   b  (S 10 ). Specifically, the control unit  2  controls the switches S 11   a , S 11   d , S 13   a , and S 13   b  to be an on state and other switches to be an off state. 
     If none of a combination of the outer left audio signal LW and the outer right audio signal RW, a combination of the upper left audio signal LH and the upper right audio signal RH, and a combination of the surround back left audio signal SBL and the surround back right audio signal SBR is included in the multichannel audio data (NO in S 11 ), then the control unit  2  controls the switches not to supply audio signals of all these channels to the SP terminals (S 12 ). Specifically, the control unit  2  controls all the switches to be an off state. 
     As described above, only with the provision of the two amplifiers  12   a  and  12   b , by determining channel information included in multichannel audio data to be inputted and switching between the switches, any one of a combination of the surround back left audio signal SBL and the surround back right audio signal SBR, a combination of the outer left audio signal LW and the outer right audio signal RW, and a combination of the upper left audio signal LH and the upper right audio signal RH can be amplified and the amplified signals can be supplied to corresponding SP terminals. 
     Next, an audio processing unit  5 B of an AV amplifier according to another preferred embodiment of the present invention will be described with reference to  FIG. 6 . A pre-out unit  21  includes switches S 21   a  to S 21   d . The switch S 21   a  switches whether to output an upper left audio signal LH to an amplifier  22   c . The switch S 21   b  switches whether to output an outer left audio signal LW to the amplifier  22   c . The switch S 21   c  switches whether to output an upper right audio signal RH to an amplifier  22   d . The switch S 21   d  switches whether to output an outer right audio signal RW to the amplifier  22   d.    
     Power amplifiers  22  include amplifiers  22   a  to  22   d . The amplifier  22   a  amplifies a surround back left audio signal SBL inputted thereto and supplies the amplified surround back left audio signal SBL to a switch S 23   a . The amplifier  22   b  amplifies a surround back right audio signal SBR inputted thereto and supplies the amplified surround back right audio signal SBR to a switch S 23   b . The amplifier  22   c  amplifies the upper left audio signal LH or the outer left audio signal LW inputted thereto and supplies the amplified audio signal to a switch S 23   c  or S 23   e . The amplifier  22   d  amplifies the upper right audio signal RH or the outer right audio signal RW inputted thereto and supplies the amplified audio signal to a switch S 23   d  or S 23   f.    
     An SP relay  23  includes the switches S 23   a  to S 23   f . The switch S 23   a  switches whether to supply the surround back left audio signal SBL inputted from the amplifier  22   a , to a surround back left SP terminal  24   a . The switch S 23   c  switches whether to supply the upper left audio signal LH inputted from the amplifier  22   c , to an upper left SP terminal  24   c . The switch S 23   c  is brought into an on state when the switch S 21   a  is in an on state. The switch S 23   e  switches whether to supply the outer left audio signal LW inputted from the amplifier  22   c , to an outer left SP terminal  24   e . The switch S 23   e  is brought into an on state when the switch S 21   b  is in an on state. 
     The switch S 23   b  switches whether to supply the surround back right audio signal SBR inputted from the amplifier  22   b , to a surround back right SP terminal  24   b . The switch S 23   d  switches whether to supply the upper right audio signal RH inputted from the amplifier  22   d , to an upper right SP terminal  24   d . The switch S 23   d  is brought into an on state when the switch S 21   c  is in an on state. The switch S 23   f  switches whether to supply the outer right audio signal RW inputted from the amplifier  22   d , to an outer right SP terminal  24   f . The switch S 23   f  is brought into an on state when the switch S 21   d  is in an on state. 
       FIG. 7  is a flowchart showing a process performed by a control unit  2  according to the present example. S 11  to S 14  are the same as S 1  to S 5  in  FIG. 5  and thus description thereof is omitted. 
     The control unit  2  determines whether a combination of the outer left audio signal LW and the outer right audio signal RW is included in multichannel audio data (S 15 ). If included (YES in S 15 ), then the control unit  2  controls the switches to supply the outer left audio signal LW to the outer left SP terminal  24   e  and supply the outer right audio signal RW to the outer right SP terminal  24   f  (S 16 ). Specifically, the control unit  2  controls the switches S 21   b , S 21   d , S 23   e , and S 23   f  to be an on state and the switches S 21   a , S 21   c , S 23   c , and S 23   d  to be an off state. 
     If determined to be NO in S 15 , then the control unit  2  determines whether a combination of the upper left audio signal LH and the upper right audio signal RH is included in the multichannel audio data (S 18 ). If included (YES in S 18 ), then the control unit  2  controls the switches to supply the upper left audio signal LH to the upper left SP terminal  24   c  and supply the upper right audio signal RH to the upper right SP terminal  24   d  (S 17 ). Specifically, the control unit  2  controls the switches S 21   a , S 21   c , S 23   c , and S 23   d  to be an on state and the switches S 21   b , S 21   d , S 23   e , and S 23   f  to be an off state. 
     If determined to be NO in S 18 , then the control unit  2  controls the switches not to supply a combination of the outer left audio signal LW and the outer right audio signal RW and a combination of the upper left audio signal LH and the upper right audio signal RH to corresponding SP terminals (S 19 ). Specifically, the control unit  2  controls the switches S 21   a  to S 21   d  and S 23   c  to S 23   f  to be an off state. 
     Next, an audio processing unit  5 C of an AV amplifier according to still another preferred embodiment of the present invention will be described with reference to  FIG. 8 . The audio processing unit  5 C is a variant of the audio processing unit  5  in  FIG. 4  and is configured to be able to use Zone2 and Bi-Amp functions. 
     A pre-out unit  31  includes switches S 31   a  to S 31   f . The switch S 31   a  switches whether to output any one of a surround back left audio signal SBL, an upper left audio signal LH, and an outer left audio signal LW inputted from a DSP, to an amplifier  32   a . Specifically, by an instruction from a control unit  2 , in the DSP, as a channel to be supplied to the switch S 31   a , any one of the surround back left audio signal SBL, the upper left audio signal LH, and the outer left audio signal LW is selected. The switch S 31   b  switches whether to output a Zone2 left audio signal Z 2 L inputted from the DSP, to the amplifier  32   a . The switch S 31   c  switches whether to output a left audio signal L (for Bi-Amp) inputted from the DSP, to the amplifier  32   a . Any one of the switches S 31   a  to S 31   c  is brought into an on state depending on whether to use the Zone2 or Bi-Amp function. 
     The switch S 31   d  switches whether to output any one of a surround back right audio signal SBR, an upper right audio signal RH, and an outer right audio signal RW inputted from the DSP, to an amplifier  32   b . Specifically, by an instruction from the control unit  2 , in the DSP, as a channel to be supplied to the switch S 31   d , any one of the surround back right audio signal SBR, the upper right audio signal RH, and the outer right audio signal RW is selected. The switch S 31   e  switches whether to output a Zone2 right audio signal Z 2 R inputted from the DSP, to the amplifier  32   b . The switch S 31   f  switches whether to output a right audio signal R (for Bi-Amp) inputted from the DSP, to the amplifier  32   b . Any one of the switches S 31   d  to S 31   f  is brought into an on state depending on whether to use the Zone2 or Bi-Amp function. 
     Power amplifiers  32  include the amplifiers  32   a  and  32   b . The amplifier  32   a  amplifies the surround back left audio signal SBL, the upper left audio signal LH, the outer left audio signal LW, the Zone2 left audio signal Z 2 L, or the left audio signal L (for Bi-Amp) inputted thereto and supplies the amplified audio signal to a corresponding one of switches S 33   a , S 33   c , and S 33   e . The amplifier  32   b  amplifies the surround back right audio signal SBR, the upper right audio signal RH, the outer right audio signal RW, the Zone2 right audio signal Z 2 R, or the right audio signal R (for Bi-Amp) inputted thereto and supplies the amplified audio signal to a corresponding one of switches S 33   b , S 33   d , and S 33   f.    
     An SP relay  33  includes the switches S 33   a  to S 33   f . The switch S 33   a  switches whether to supply the surround back left audio signal SBL, the Zone2 left audio signal Z 2 L, or the left audio signal L (for Bi-Amp) inputted from the amplifier  32   a , to a surround back left SP terminal  34   a . The switch S 33   a  is brought into an on state when the switch S 31   a  is in an on state and the surround back left audio signal SBL is supplied to the switch S 31   a , when the switch S 31   b  is in an on state, or when the switch S 31   c  is in an on state. The switch S 33   c  switches whether to supply the upper left audio signal LH inputted from the amplifier  32   a , to an upper left SP terminal  34   c . The switch S 33   c  is brought into an on state when the switch S 31   a  is in an on state and the upper left audio signal LH is supplied to the switch S 31   a . The switch S 33   e  switches whether to supply the outer left audio signal LW inputted from the amplifier  32   a , to an outer left SP terminal  34   e . The switch S 33   e  is brought into an on state when the switch S 31   a  is in an on state and the outer left signal LW is supplied to the switch S 31   a.    
     The switch S 33   b  switches whether to supply the surround back right audio signal SBR, the Zone2 right audio signal Z 2 R, or the right audio signal R (for Bi-Amp) inputted from the amplifier  32   b , to a surround back right SP terminal  34   b . The switch S 33   b  is brought into an on state when the switch S 31   d  is in an on state and the surround back right audio signal SBR is supplied to the switch S 31   d , when the switch S 31   e  is in an on state, or when the switch S 31   f  is in an on state. The switch S 33   d  switches whether to supply the upper right audio signal RH inputted from the amplifier  32   b , to an upper right SP terminal  34   d . The switch S 33   d  is brought into an on state when the switch S 31   d  is in an on state and the upper right audio signal RH is supplied to the switch S 31   d . The switch S 33   f  switches whether to supply the outer right audio signal RW inputted from the amplifier  32   b , to an outer right SP terminal  34   f . The switch S 33   f  is brought into an on state when the switch S 31   d  is in an on state and the outer right audio signal RW is supplied to the switch S 31   d.    
     SP terminals  34  include the SP terminals  34   a  to  34   f . When the functions are not used, the same speakers as those described above are connected to the SP terminals. When the Zone2 function is used, a Zone2 left speaker SZ 2 L is connected to the surround back left SP terminal  34   a  and a Zone2 right speaker SZ 2 R is connected to the surround back right SP terminal  34   b . When the Bi-Amp function is used, a Bi-Amp terminal of a left speaker SL is connected to the surround back left SP terminal  34   a  and a Bi-Amp terminal of a right speaker SR is connected to the surround back right SP terminal  34   b.    
     Next, operations in the present example will be described. 
     (1) When the Bi-Amp Function is Used 
     The control unit  2  controls the DSP and the switches to supply the left audio signal L (for Bi-Amp) to the surround back left SP terminal  34   a  and supply the right audio signal R (for Bi-Amp) to the surround back right SP terminal  34   b . Specifically, the control unit  2  causes the DSP to supply the left audio signal L (for Bi-Amp) to the switch S 31   c  and supply the right audio signal R (for Bi-Amp) to the switch S 31   f . The control unit  2  controls the switches S 31   c , S 31   f , S 33   a , and S 33   b  to be an on state and other switches to be an off state. 
     (2) When the Zone2 Function is Used 
     The control unit  2  controls the DSP and the switches to supply the Zone2 left audio signal Z 2 L to the surround back left SP terminal  34   a  and supply the Zone2 right audio signal Z 2 R to the surround back right SP terminal  34   b . Specifically, the control unit  2  causes the DSP to supply the Zone2 left audio signal Z 2 L to the switch S 31   b  and supply the Zone2 right audio signal Z 2 R to the switch S 31   e . The control unit  2  controls the switches S 31   b , S 31   e , S 33   a , and S 33   b  to be an on state and other switches to be an off state. 
     (3) When a Combination of the Outer Left Audio Signal LW and the Outer Right Audio Signal RW is Included 
     The control unit  2  controls the DSP and the switches to supply the outer left audio signal LW to the outer left SP terminal  34   e  and supply the outer right audio signal RW to the outer right SP terminal  34   f . Specifically, the control unit  2  causes the DSP to supply the outer left audio signal LW to the switch S 31   a  and supply the outer right audio signal RW to the switch S 31   d . The control unit  2  controls the switches S 31   a , S 31   d , S 33   e , and S 33   f  to be an on state and other switches to be an off state. 
     (4) When a Combination of the Upper Left Audio Signal LH and the Upper Right Audio Signal RH is Included 
     The control unit  2  controls the DSP and the switches to supply the upper left audio signal LH to the upper left SP terminal  34   c  and supply the upper right audio signal RH to the upper right SP terminal  34   d . Specifically, the control unit  2  causes the DSP to supply the upper left audio signal LH to the switch S 31   a  and supply the upper right audio signal RH to the switch S 31   d . The control unit  2  controls the switches S 31   a , S 31   d , S 33   c , and S 33   d  to be an on state and other switches to be an off state. 
     (5) A Combination of the Surround Back Left Audio Signal SBL and the Surround Back Right Audio Signal SBR is Included 
     The control unit  2  controls the DSP and the switches to supply the surround back left audio signal SBL to the surround back left SP terminal  34   a  and supply the surround back right audio signal SBR to the surround back right SP terminal  34   b . Specifically, the control unit  2  causes the DSP to supply the surround back left audio signal SBL to the switch S 31   a  and supply the surround back right audio signal SBR to the switch S 31   d . The control unit  2  controls the switches S 31   a , S 31   d , S 33   a , and S 33   b  to be an on state and other switches to be an off state. 
     Next, an audio processing unit  5 D of an AV amplifier according to yet another preferred embodiment of the present invention will be described with reference to  FIG. 9 . The audio processing unit  5 D is a variant of the audio processing unit  5 B in  FIG. 6  and is configured to allow Zone2, Zone3, Bi-Amp, BTL, speaker B, and passive sub-woofer output functions to be applicable thereto. 
     A pre-out unit  41  includes switches S 41   a  to S 41   n . The switch S 41   a  switches whether to output a surround back left audio signal SBL inputted from a DSP, to an amplifier  42   a . The switch S 41   b  switches whether to output a Zone3 left audio signal Z 3 L inputted from the DSP, to the amplifier  42   a . The switch S 41   c  switches whether to output a left audio signal L (for Bi-Amp) inputted from the DSP, to the amplifier  42   a . The switch S 41   d  switches whether to output a BTL left audio signal L− to the amplifier  42   a . Any one of the switches S 41   a  to S 41   d  is brought into an on state depending on whether to use the functions. 
     The switch S 41   e  switches whether to output a surround back right audio signal SBR inputted from the DSP, to an amplifier  42   b . The switch S 41   f  switches whether to output a Zone3 right audio signal Z 3 R inputted from the DSP, to the amplifier  42   b . The switch S 41   g  switches whether to output a right audio signal R (for Bi-Amp) inputted from the DSP, to the amplifier  42   b . The switch S 41   h  switches whether to output a BTL right audio signal R− to the amplifier  42   b . Any one of the switches S 41   e  to S 41   h  is brought into an on state depending on whether to use the functions. 
     The switch S 41   i  switches whether to output an upper left audio signal LH or an outer left audio signal LW inputted from the DSP, to an amplifier  42   c . Specifically, in the DSP, as a channel to be supplied to the switch S 41   i , one of the upper left audio signal LH and the outer left audio signal LW is selected. The switch S 41   j  switches whether to output a low-frequency audio signal SW inputted from the DSP, to the amplifier  42   c . The switch S 41   k  switches whether to output a Zone2 left audio signal Z 2 L inputted from the DSP, to the amplifier  42   c . Any one of the switches S 41   i  to S 41   k  is brought into an on state depending on whether to use the functions. 
     The switch S 41   l  switches whether to output an upper right audio signal RH or an outer right audio signal RW inputted from the DSP, to an amplifier  42   d . Specifically, in the DSP, as a channel to be supplied to the S 41   l , one of the upper right audio signal RH and the outer right audio signal RW is selected. The switch S 41   m  switches whether to output a low-frequency audio signal SW inputted from the DSP, to the amplifier  42   d . The switch S 41   n  switches whether to output a Zone2 right audio signal Z 2 R inputted from the DSP, to the amplifier  42   d . Any one of the switches S 41   l  to  41   n  is brought into an on state depending on whether to use the functions. 
     Power amplifiers  42  include the amplifiers  42   a  to  42   d . The amplifier  42   a  amplifies the surround back left audio signal SBL, the Zone3 left audio signal Z 3 L, the left audio signal L (for Bi-Amp), or the BTL left audio signal L− inputted thereto and supplies the amplified audio signal to a switch S 43   a . The amplifier  42   b  amplifies the surround back right audio signal SBR, the Zone3 right audio signal Z 3 R, the right audio signal R (for Bi-Amp), or the BTL right audio signal R− inputted thereto and supplies the amplified audio signal to a switch S 43   b . The amplifier  42   c  amplifies the upper left audio signal LH, the outer left audio signal LW, the low-frequency audio signal SW, or the Zone2 left audio signal Z 2 L inputted thereto and supplies the amplified audio signal to a switch S 43   c . The amplifier  42   d  amplifies the upper right audio signal RH, the outer right audio signal RW, the low-frequency audio signal SW, or the Zone2 right audio signal Z 2 R inputted thereto and supplies the amplified audio signal to a switch S 43   d . An amplifier  42   e  is an amplifier for a left audio signal L, amplifies the left audio signal L supplied from the DSP, and supplies the amplified left audio signal L to a switch S 43   f . An amplifier  42   f  is an amplifier for a right audio signal R, amplifies the right audio signal R supplied from the DSP, and supplies the amplified right audio signal R to a switch S 43   h.    
     An SP relay  43  includes the switches S 43   a  to S 43   h . The switch S 43   a  switches whether to supply the surround back left audio signal SBL, the Zone3 left audio signal Z 3 L, the left audio signal L (for Bi-Amp), or the BTL left audio signal L− inputted from the amplifier  42   a , to a surround back left SP terminal  44   a . The switch S 43   a  goes to an on state when any one of the switches S 41   a  to S 41   d  is in an on state. The switch S 43   b  switches whether to supply the surround back right audio signal SBR, the Zone3 right audio signal Z 3 R, the right audio signal R (for Bi-Amp), or the BTL right audio signal R− inputted from the amplifier  42   b , to a surround back right SP terminal  44   b . The switch S 43   b  goes to an on state when any one of the switches S 41   e  to S 41   h  is in an on state. 
     The switch S 43   c  switches whether to supply the upper left audio signal LH or the low-frequency audio signal SW inputted from the amplifier  42   c , to an upper left SP terminal  44   c . The switch S 43   c  is brought into an on state when the switch S 41   i  is in an on state and the upper left audio signal LH is supplied to the switch S 41   i  or when the switch S 41   j  is in an on state. The switch S 43   d  switches whether to supply the upper right audio signal RH or the low-frequency audio signal SW inputted from the amplifier  42   d , to an upper right SP terminal  44   d . The switch S 43   d  is brought into an on state when the switch S 41   l  is in an on state and the upper right audio signal RH is supplied to the switch S 41   l  or when the switch S 41   m  is in an on state. 
     A switch S 43   e  switches whether to supply the outer left audio signal LW or the Zone2 left audio signal Z 2 L inputted from the amplifier  42   c , to an outer left SP terminal  44   e . The switch S 43   e  is brought into an on state when the switch S 41   i  is in an on state and the outer left audio signal LW is supplied to the switch S 41   i  or when the switch S 41   k  is in an on state. A switch S 43   g  switches whether to supply the outer right audio signal RW or the Zone2 right audio signal Z 2 R inputted from the amplifier  42   d , to an outer right SP terminal  44   f . The switch S 43   g  is brought into an on state when the switch S 41   l  is in an on state and the outer right audio signal RW is supplied to the switch S 41   l  or when the switch S 41   n  is in an on state. 
     The switch S 43   f  switches whether to supply the left audio signal L (for speaker B) inputted from the amplifier  42   e , to the outer left SP terminal  44   e . The switch S 43   h  switches whether to supply the right audio signal R (for speaker B) inputted from the amplifier  42   f , to the outer right SP terminal  44   f.    
     SP terminals  44  include the SP terminals  44   a  to  44   f . When the functions are not used, the same speakers as those described above are connected to the SP terminals. When the Zone3 function is used, a Zone3 left speaker SZ 3 L is connected to the surround back left SP terminal  44   a  and a Zone3 right speaker SZ 3 R is connected to the surround back right SP terminal  44   b . When the Bi-Amp function is used, a Bi-Amp terminal of a left speaker SL is connected to the surround back left SP terminal  44   a  and a Bi-Amp terminal of a right speaker SR is connected to the surround back right SP terminal  44   b . When the BTL function is used, a − side of the left speaker SL is connected to the surround back left SP terminal  44   a  and a − side of the right speaker SR is connected to the surround back right SP terminal  44   b . When the passive sub-woofer output function is used, a passive sub-woofer (a speaker dedicated to low frequencies, which is not built in the amplifier) is connected to the upper left SP terminal  44   c  and the upper right SP terminal  44   d . When the Zone2 function is used, a Zone2 left speaker SZ 2 L is connected to the outer left SP terminal  44   e  and a Zone2 right speaker SZ 2 R is connected to the outer right SP terminal  44   f . When the speaker B function is used, a speaker B left speaker SLB is connected to the outer left SP terminal  44   e  and a speaker B right speaker SRB is connected to the outer right SP terminal  44   f.    
     Next, operations in the present example will be described. 
     (1) When the Bi-Amp Function is Used 
     A control unit  2  controls the DSP and the switches to supply the left audio signal L (for Bi-Amp) to the surround back left SP terminal  44   a  and supply the right audio signal R (for Bi-Amp) to the surround back right SP terminal  44   b . Specifically, the control unit  2  causes the DSP to supply the left audio signal L (for Bi-Amp) to the switch S 41   c  and supply the right audio signal R (for Bi-Amp) to the switch S 41   g . The control unit  2  controls the switches S 41   c , S 41   g , S 43   a , and S 43   b  to be an on state and the switches S 41   a , S 41   b , S 41   d , S 41   e , S 41   f , and S 41   h  to be an off state. 
     (2) When the BTL Function is Used The control unit  2  controls the DSP and the switches to supply the BTL left audio signal L− to the surround back left SP terminal  44   a  and supply the BTL right audio signal R− to the surround back right SP terminal  44   b . Specifically, the control unit  2  causes the DSP to supply the BTL left audio signal L− to the switch S 41   d  and supply the BTL right audio signal R− to the switch S 41   h . The control unit  2  controls the switches S 41   d , S 41   h , S 43   a , and S 43   b  to be an on state and the switches S 41   a , S 41   b , S 41   c , S 41   e , S 41   f , and S 41   g  to be an off state. 
     (3) When the Speaker B Function is Used 
     The control unit  2  controls the DSP and the switches to supply the left audio signal L to the outer left SP terminal  44   e  and supply the right audio signal R to the outer right SP terminal  44   f . Specifically, the control unit  2  controls the switches S 43   f  and S 43   h  to be an on state and the switches S 41   i  to S 41   n , S 43   c , S 43   d , S 43   e , and S 43   g  to be an off state. 
     (4) When the Passive Sub-Woofer Output Function is Used 
     The control unit  2  controls the DSP and the switches to supply the low-frequency audio signal SW to the upper left SP terminal  44   c  and the upper right SP terminal  44   d . Specifically, the control unit  2  causes the DSP to supply the low-frequency audio signal SW to the switches S 41   j  and S 41   m . The control unit  2  controls the switches S 41   j , S 41   m , S 43   c , and S 43   d  to be an on state and the switches S 41   i , S 41   k , S 41   l , S 41   n , S 43   e , S 43   f , S 43   g , and S 43   h  to be an off state. 
     (5) When the Zone2 Function is Used 
     The control unit  2  controls the DSP and the switches to supply the Zone2 left audio signal Z 2 L to the outer left SP terminal  44   e  and supply the Zone2 right audio signal Z 2 R to the outer right SP terminal  44   f . Specifically, the control unit  2  causes the DSP to supply the Zone2 left audio signal Z 2 L to the switch S 41   k  and supply the Zone2 right audio signal Z 2 R to the switch S 41   n . The control unit  2  controls the switches S 41   k , S 41   n , S 43   e , and S 43   g  to be an on state and the switches S 41   i , S 41   j , S 41   l , S 41   m , S 43   c , S 43   d , S 43   f , and S 43   g  to be an off state. 
     (6) When the Zone3 Function is Used 
     The control unit  2  controls the DSP and the switches to supply the Zone3 left audio signal Z 3 L to the surround back left SP terminal  44   a  and supply the Zone3 right audio signal Z 3 R to the surround back right SP terminal  44   b . Specifically, the control unit  2  causes the DSP to supply the Zone3 left audio signal Z 3 L to the switch S 41   b  and supply the Zone3 right audio signal Z 3 R to the switch S 41   f . The control unit  2  controls the switches S 41   b , S 41   f , S 43   a , and S 43   b  to be an on state and the switches S 41   a , S 41   c , S 41   d , S 41   e , S 41   g , and S 41   h  to be an off state. 
     (7) When a Combination of the Outer Left Audio Signal LW and the Outer Right Audio Signal RW is Included 
     The control unit  2  controls the DSP and the switches to supply the outer left audio signal LW to the outer left SP terminal  44   e  and supply the outer right audio signal RW to the outer right SP terminal  44   f . Specifically, the control unit  2  causes the DSP to supply the outer left audio signal LW to the switch S 41   i  and supply the outer right audio signal RW to the switch S 41   l . The control unit  2  controls the switches S 41   i , S 41   l , S 43   e , and S 43   g  to be an on state and the switches S 41   j , S 41   k , S 41   m , S 41   n , S 43   c , S 43   d , S 43   f , and S 43   h  to be an off state. 
     (8) When a Combination of the Upper Left Audio Signal LH and the Upper Right Audio Signal RH is Included 
     The control unit  2  controls the DSP and the switches to supply the upper left audio signal LH to the upper left SP terminal  44   c  and supply the upper right audio signal RH to the upper right SP terminal  44   d . Specifically, the control unit  2  causes the DSP to supply the upper left audio signal LH to the switch S 41   i  and supply the upper right audio signal RH to the switch S 41   l . The control unit  2  controls the switches S 41   i , S 41   l , S 43   c , and S 43   d  to be an on state and the switches S 41   j , S 41   k , S 41   m , S 41   n , S 43   e , S 43   f , S 43   g , and S 43   h  to be an off state. 
     (9) When a Combination of the Surround Back Left Audio Signal SBL and the Surround Back Right Audio Signal SBR is Included 
     The control unit  2  controls the DSP and the switches to supply the surround back left audio signal SBL to the surround back left SP terminal  44   a  and supply the surround back right audio signal SBR to the surround back right SP terminal  44   b . Specifically, the control unit  2  causes the DSP to supply the surround back left audio signal SBL to the switch S 41   a  and supply the surround back right audio signal SBR to the switch S 41   e . The control unit  2  controls the switches S 41   a , S 41   e , S 43   a , and S 43   b  to be an on state and the switches S 41   b , S 41   c , S 41   d , S 41   f , S 41   g , and S 41   h  to be an off state. 
     Although the preferred embodiments of the present invention are described above, the present invention is not limited thereto. Instead of an upper left audio signal and an upper right audio signal, a center left audio signal (a signal between a left audio signal and a center audio signal) and a center right audio signal (a signal between a right audio signal and the center audio signal) may be applied. The present invention may also be provided in the form of a program that causes a computer to perform the above-described operations of an AV amplifier, and a recording medium recording the program.