Abstract:
A digital broadcast reception device, provided with a first audio decoder for expanding and outputting a compressed digital audio signal included in the transport stream of a received digital broadcast; an encoder for encoding at least the digital audio signal outputted by the first audio decoder; and a second audio decoder for decoding the compressed digital audio signal outputted by the encoder.

Description:
[0001]    This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2011-179396 filed in Japan on Aug. 19, 2011, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a digital broadcast reception device for receiving a digital broadcast. 
         [0004]    2. Description of Related Art 
         [0005]    A digital broadcast reception device for receiving a digital broadcast is provided with a video/audio processor for processing the transport stream of the received digital broadcast. Herein, a simplified configuration example of a video/audio processor provided to a typical digital broadcast receiver device is shown in  FIG. 9 . 
         [0006]    The video/audio processor shown in  FIG. 9  is provided with a separating section  201  for separating the transport stream of the received digital broadcast into a compressed digital video signal, a compressed digital audio signal, etc.; a video decoder  202  for expansion and output of the compressed digital video signal sent to it by the separating section  201 ; an audio decoder  203  for expansion and output of the compressed digital audio signal sent to it by the separating section  201 ; a video D/A converter  204  for D/A conversion of the digital video signal outputted by the video decoder  202 , and output of an analog video signal; and an audio D/A converter  205  for D/A conversion of a pulse code modulation (PCM) digital audio signal, which is the digital audio signal outputted by the audio decoder  203 , and output of an analog audio signal. 
         [0007]    From the video/audio processor shown in  FIG. 9 , it will be appreciated that the output analog audio signal retains the same level as that intended by the broadcaster. 
         [0008]    Meanwhile, multiple channels and higher dynamic ranges are trends that are associated with digitization of broadcasts, and there are sometimes large differences in volume among different broadcast programs, among different channels, between the main part of a broadcast program and a commercial (hereinafter sometimes denoted as CM), and so on. Despite the fact that the analog audio signal outputted by the video/audio processor retains the same level as that intended by the broadcaster, if such differences in volume occur frequently, the user will be compelled to constantly make adjustments of the volume, which is inconvenient for the user. 
         [0009]    Accordingly, in Japanese Laid-Open Patent Application 2008-41144, there was proposed a content recording device adapted to receive compressed content over a network, and to record the received content into storage means, the content recording device being equipped with decoding means for decoding the content; volume level adjusting means for adjusting the volume of the content decoded by the decoding means to an established baseline volume level; and encoding means for encoding the content that has been adjusted to the baseline volume level by the volume level adjusting means, doing so at an established baseline compression ratio, wherein the content encoded at the baseline compression ratio by the encoding means is recorded into the storage means. 
         [0010]    Additionally, Japanese Laid-Open Patent Application 2002-112173 discloses a recording/playback device adapted to record an input audio signal into a recording medium, and to play it back, the recording/playback device being provided with volume varying means capable of varying the volume of an output audio signal relative an input audio signal, detecting means for detecting that an input audio signal is a commercial signal, and audio control means that, in a case in which a commercial signal has been detected by the detecting means, controls the volume varying means to vary the volume of the audio signal. 
         [0011]    With the devices disclosed in Japanese Laid-Open Patent Application 2008-41144 and Japanese Laid-Open Patent Application 2002-112173, the amount of labor expended by the user in making volume adjustments can be reduced by actual automatic adjustment of the volume. However, because an adjusting section is necessary to make the actual automatic adjustments of the volume, there are limitations in terms of the configuration. 
         [0012]    An information processing device proposed in Japanese Laid-Open Patent Application 2009-49474, which can adjust the bit rate according to the degree of importance of a scene, is furnished with a volume detecting section that in a case in which, for example, the volume of cheering has been detected, and an evaluation value has been established based on the percentage of the volume of the cheering, can detect the volume of the cheering. As such, the invention relates to volume, but cannot reduce the amount of labor expended by the user in making volume adjustments. 
       SUMMARY OF THE INVENTION 
       [0013]    It is an object of the present invention to offer a digital broadcast reception device that can reduce the amount of effort expended by the user in making volume adjustments, despite not being furnished with an adjusting section for making actual automatic adjustments of volume. 
         [0014]    In order to achieve the aforementioned object, the digital broadcast reception device according to the present invention comprises a first audio decoder for expanding and outputting a compressed digital audio signal included in a transport stream of a received digital broadcast; 
         [0015]    an encoder for encoding at least the digital audio signal outputted by the first audio decoder; and 
         [0016]    a second audio decoder for decoding the compressed digital audio signal outputted by the encoder. 
         [0017]    Optionally, the device comprises an audio D/A convertor for D/A conversion of the digital audio signal outputted by the second audio decoder, and outputting an analog audio signal. 
         [0018]    Optionally, the encoder is an encoder that can modify the bit rate of audio encoding. In this case, the encoder modifies the bit rate of audio encoding so as to be smaller subsequent to modification than prior to modification in a case in which a switch from the main part of a broadcast program to a commercial has detected, and the difference in volume between the main part and the commercial is equal to or greater than a threshold. 
         [0019]    Optionally, the device is provided with a bypass route bypassing the encoder and the second audio decoder. In this case, the bypass route is switched from a state of use to a state of non-use in a case in which a switch from a main part of a broadcast program to a commercial has been detected, and a difference in volume between the main part and the commercial is equal to or greater than a threshold. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a diagram showing a simplified configuration of an HDD-equipped optical disc recorder according to an embodiment of the present invention; 
           [0021]      FIG. 2  is a diagram showing a simplified example configuration of a video/audio processor provided to an HDD-equipped optical disc recorder according to an embodiment of the present invention; 
           [0022]      FIG. 3  is a diagram showing another simplified example configuration of a video/audio processor provided to an HDD-equipped optical disc recorder according to an embodiment of the present invention; 
           [0023]      FIG. 4  is a diagram showing yet another simplified example configuration of a video/audio processor provided to an HDD-equipped optical disc recorder according to an embodiment of the present invention; 
           [0024]      FIG. 5  is a flowchart showing an example of operation of a video/audio processor; 
           [0025]      FIG. 6  is a flowchart showing another example of operation of a video/audio processor; 
           [0026]      FIG. 7  is a diagram showing a simplified example configuration of a video/audio processor having a bypass route, provided to an HDD-equipped optical disc recorder according to an embodiment of the present invention; 
           [0027]      FIG. 8  is a flowchart showing an example of operation of a video/audio processor having a bypass route; and 
           [0028]      FIG. 9  is a diagram showing a simplified example configuration of a video/audio processor provided to an ordinary digital broadcast reception device. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0029]    The embodiments of the present invention are described below with reference to the accompanying drawings. The example of the digital broadcast reception device according to the present invention described herein is that of a hard disk drive (HDD)-equipped optical disc recorder. 
         [0030]    A simplified configuration of an HDD-equipped recorder according to an embodiment of the present invention is shown in  FIG. 1 . The HDD-equipped optical disc recorder  100  according to the embodiment of the present invention shown in  FIG. 1  (hereinafter abbreviated to “HDD-equipped optical disc recorder  100 ”) is provided with a digital tuner  1 , a video/audio processor  2 , an on-screen display (OSD) section  3 , an output section  4 , an HDD recording/playback section  5 , an optical disc recording/playback section  6 , a controller  7 , a nonvolatile memory  8 , a light-receiving section  9 , and a main unit operation key group  10 . 
         [0031]    The digital tuner  1  performs selection and demodulation (for example, orthogonal frequency division multiplexing (OFDM) demodulation) of a TV broadcast signal received by an antenna ANT. The video/audio processor  2  performs signal processing of a video/audio signal included in the transport stream received from the digital tuner  1 , or of a video/audio signal played back by the HDD recording/playback section  5  or the optical disc recording/playback section  6 , and sends it to the output section  4 ; or sends a video/audio signal included in the transport stream received from the digital tuner  1  to the HDD recording/playback section  5  or the optical disc recording/playback section  6 . The OSD section  3  sends OSD image data generated based on an instruction from the controller  7  to the output section  4 . The output section  4  outputs to the outside a synthesized video signal synthesized from the analog video signal received from the video/audio processor  2  and the OSD image data received from the OSD section  3 ; directly outputs the analog video signal received from the video/audio processor  2  to the outside without performing the aforementioned synthesis process; directly outputs the OSD image data received from the OSD section  3  to the outside without performing the aforementioned synthesis process; or outputs to the outside an analog audio signal received from the video/audio processor  2 . The output signal of the output section  4  is transmitted to a television receiver (not shown) connected to the HDD-equipped optical disc recorder  100 . The television receiver connected to the HDD-equipped optical disc recorder  100  displays images and outputs audio based on the output signal of the output section. 
         [0032]    The HDD recording/playback section  5  records onto a hard disk a video/audio signal received from the video/audio processor  2 , or plays back a video/audio signal that has been recorded onto the hard disk. The optical disc recording/playback section  6  records onto an optical disc a video/audio signal received from the video/audio processor  2 , or plays back a video/audio signal that has been recorded onto an optical disc. The optical disc is removably installed in the optical disc recording/playback section  6 . 
         [0033]    The light-receiving section  9  receives a remote control infrared signal transmitted by a remote control transmitter (not shown) and converts it to an electrical signal, then extracts an operation code from the electrical signal, for output to the controller  7 . The controller  7  controls the various sections of the HDD-equipped optical disc recorder  100 , in response to a control program and various settings (for example, a data table containing associations between operation codes and various functions, or the like) stored in the nonvolatile memory  8 , to an operation code received from the light-receiving section  9 , and to an operation code defined by a signal output from the main unit operation key group  10 , which has a plurality of main unit keys. 
         [0034]    Next, the video/audio processor  2  provided to the HDD-equipped optical disc recorder  100  is configured as shown in  FIG. 2 , or configured as shown in  FIG. 3 , for example. 
         [0035]    In the configuration shown in  FIG. 2 , the video/audio processor  2  is provided with a separating section  101  for separating the transport stream of a received digital broadcast into a compressed digital video signal, a compressed digital audio signal, etc.; a video decoder  102  for expansion and output of the compressed digital video signal sent to it by the separating section  101 ; an audio decoder  103  for expansion and output of the compressed digital audio signal sent to it by the separating section  101 ; a video D/A converter  104  for D/A conversion of the digital video signal outputted by the video decoder  102 , and output of an analog video signal; an encoder  105  for encoding a PCM digital audio signal, which is the digital audio signal outputted by the audio decoder  103 ; an audio decoder  106  for decoding the compressed digital audio signal outputted by the encoder  105 ; and an audio D/A converter  107  for D/A conversion of the PCM digital audio signal which is the digital audio signal outputted by the audio decoder  106 , and output of an analog audio signal. The encoder  105  is an encoder that can modify the bit rate of encoding. 
         [0036]    In the configuration shown in  FIG. 3 , in place of the encoder  105  in the configuration shown in  FIG. 2 , the configuration is furnished instead with an encoder  108  for encoding the digital video signal outputted by the video decoder  102  and the digital audio signal outputted by the audio decoder  103 ; additionally furnished with a video decoder  109  between the encoder  108  and the video D/A converter  104 ; and also furnished with an audio decoder  110  between the encoder  108  and the audio D/A converter  107 . Consequently, with the configuration shown in  FIG. 3 , the encoder  108  encodes the digital video signal outputted by the video decoder  102  and the digital audio signal outputted by the audio decoder  103 ; the video decoder  109  decodes the compressed digital video signal outputted by the encoder  108 ; the audio decoder  110  decodes the compressed digital audio signal outputted by the encoder  108 ; the video D/A converter  104  performs D/A conversion of the digital video signal outputted by the video decoder  109 , and outputs an analog video signal; and the audio D/A converter  107  performs D/A conversion of the PCM digital audio signal, which is the digital audio signal outputted by the audio decoder  110 , and outputs an analog audio signal. The encoder  108  is an encoder that can modify the bit rate of audio encoding. 
         [0037]    With the configuration shown in  FIG. 3 , because the encoder  108  processes the video signal and the audio signal simultaneously, no lag arises between the analog video signal and the analog audio signal. In contrast to this, with the configuration shown in  FIG. 2 , when the processing time of the encoder  105  and the audio decoder  106  is prolonged, the analog audio signal will be delayed with respect to the analog video signal. Consequently, in cases of prolonged processing time of the encoder  105  and the audio decoder  106 , a delay circuit  111  may be furnished between the video decoder  102  and the video D/A converter  104 , as in the configuration shown in  FIG. 4  for example. 
         [0038]    Next, an example of operation of the video/audio processor  2  will be described with reference to the flowchart shown in  FIG. 5 . 
         [0039]    When the video/audio processor  2  starts operation, each section of the video/audio processor  2  starts to operate (Step S 10 ). In Step S 20  which follows Step S 10 , a switch between the main part of a broadcast program (which is not limited to one sent from the digital tuner  1 , and includes, for example, a broadcast program played back by the HDD recording/playback section  5  or the optical disc recording/playback section  6 ) and a CM is detected; and additionally a determination as made as to whether the difference in volume between the main part and the CM is equal to or greater than a threshold. The agent that makes the determination may be, for example, the controller  7 , which performs the determination in question based on information outputted by the video/audio processor  2 , and sends the result of the determination to the video/audio processor  2 ; or a controller (not shown) disposed in the video/audio processor  2 , and that controls the entire video/audio processor  2 . As a method for detecting a switch between the main part and a CM, there may be cited, for example, a method in which the audio signal outputted by the audio decoder is employed to detect the volume, designating an interval of loud volume as a CM, and an interval of soft volume as the main part. 
         [0040]    In a case in which a switch between the main part of a broadcast program and a CM has not been detected, or in a case in which a switch between the main part of a broadcast program and a CM has been detected, but the difference in volume between the main part and the CM is less than the threshold (NO in Step S 20 ), the system returns to Step S 20 , and continues the aforementioned determination process. 
         [0041]    On the other hand, in a case in which a switch between the main part of a broadcast program and a CM has been detected, and moreover the difference in volume between the main part and the CM is equal to or greater than the threshold (YES in Step S 20 ), the encoder  105  or  108  temporarily halts encoding (Step S 30 ). For the purpose of entry into this temporary halt operation, optionally, a buffer memory or the like may be furnished in an earlier stage from the encoder  105  or  108 . 
         [0042]    In Step S 40  which follows Step S 30 , the encoder  105  or  108  modifies the bit rate of audio encoding. When there has been a switch from the main part to a CM, the bit rate of audio encoding is modified such that that subsequent to modification is less than that prior to modification, whereas when there has been a switch from a CM to the main part, the bit rate of audio encoding is modified such that that subsequent to modification is greater than that prior to modification. 
         [0043]    In Step S 50  which follows Step S 40 , the encoder  105  or  108  resumes encoding, then returns to Step S 20 , and continues the aforementioned determination process. 
         [0044]    In a case in which the encoder  105  or  108  has lowered the bit rate of audio encoding, the sound quality of the analog audio signal obtained by subsequent decoding may be poor, making it hard for the user to hear. Therefore the user may have the illusion that the volume is lower. Specifically, due to lowering of the bit rate of audio encoding by the encoder  105  or  108 , it is possible for the volume to appear lower in illusory fashion, with no actual lowering of the volume. 
         [0045]    Moreover, large differences in volume occur not just between the main part of a broadcast program and CM, but in some cases may occur between different broadcast programs, between different channels, between different sources of content (for example, between a non-external input system and an external input system, or between a terrestrial digital broadcast and a satellite digital broadcast, etc.). For this reason, the video/audio processor  2  may be designed to perform the operation shown in  FIG. 6 , for example. In the flowchart shown in  FIG. 6 , Steps S 21  to S 23  have been added to the flowchart shown in  FIG. 5 . 
         [0046]    In the flowchart shown in  FIG. 6 , a case in which no switch between the main part of a broadcast program and a CM has been detected, or in a case in which a switch between the main part of a broadcast program and a CM has been detected, but the difference in volume between the main part and the CM is less than the threshold (NO in Step S 20 ), the system proceeds to Step S 21 . In a case in which a switch between the main part of a broadcast program and a CM has been detected, and moreover the difference in volume between the main part and the CM is equal to or greater than the threshold (YES in Step S 20 ), the system proceeds to Step S 30 , in the same way as in the flowchart shown in  FIG. 5 . 
         [0047]    In Step S 21 , a switch from one broadcast program to another broadcast program is detected, and a determination is made as to whether the difference in volume between the one broadcast program and the other broadcast program is equal to or greater than a threshold. The agent that makes the determination of Step S 21  may be, for example, the controller  7 , which employs EPG or the like to perform the determination, and sends the result of the determination to the video/audio processor  2 . 
         [0048]    In a case in which a switch from one broadcast program to another broadcast program has not been detected, or in a case in which a switch from one broadcast program to another broadcast program has been detected, but the difference in volume between the one broadcast program and the other broadcast program is less than the threshold (NO in Step S 21 ), the system proceeds to Step S 22 . On the other hand, in a case in which a switch from one broadcast program to another broadcast program has been detected, and moreover the difference in volume between the one broadcast program and the other broadcast program is equal to or greater than the threshold (YES in Step S 21 ), the system proceeds to Step S 30 . 
         [0049]    In Step S 22 , a switch from one channel to another channel is detected, and a determination is made as to whether the difference in volume between the one channel and the other channel is equal to or greater than a threshold. The agent that makes the determination of Step S 22  may be, for example, the controller  7 , which performs the determination from an ascertained selection state, and sends the result of the determination to the video/audio processor  2 . 
         [0050]    In a case in which a switch from one channel to another channel has not been detected, or in a case in which a switch from one channel to another channel has been detected, but the difference in volume between the one channel and the other channel is less than the threshold (NO in Step S 22 ), the system proceeds to Step S 23 . On the other hand, in a case in which a switch from one channel to another channel has been detected, and moreover the difference in volume between the one channel and the other channel is equal to or greater than the threshold (YES in Step S 22 ), the system proceeds to Step S 30 . 
         [0051]    In Step S 23 , a switch from one source of content to another source of content is detected, and a determination is made as to whether the difference in volume between the one source of content and the other source of content is equal to or greater than a threshold. The agent that makes the determination of Step S 23  may be, for example, the controller  7 , which performs the determination from an ascertained content source, and sends the result of the determination to the video/audio processor  2 . 
         [0052]    In a case in which a switch from one source of content to another source of content has not been detected, or in a case in which a switch from one source of content to another source of content has been detected, but the difference in volume between the one source of content and the other source of content is less than the threshold (NO in Step S 23 ), the system returns to Step S 20 . On the other hand, in a case in which a switch from one source of content to another source of content has been detected, and moreover the difference in volume between the one source of content and the other source of content is equal to or greater than the threshold (YES in Step S 23 ), the system proceeds to Step S 30 . 
         [0053]    Next, a video/audio processor  2  having a bypass route will be described. Whereas the configuration of the video/audio processor  2  discussed previously (see  FIGS. 2 to 4 ) is one that does not have a bypass route, a configuration having a bypass route  112 , as shown in  FIG. 7 , is also possible. The configuration of the video/audio processor  2  shown in  FIG. 7  is equivalent to the configuration shown in  FIG. 2 , but with the addition of the bypass route  112  and switches  113  and  114 . The switch  113  alternately selects between the encoder  105  and the bypass route  112 , and supplies the selected one with the PCM digital audio signal outputted by the audio decoder  103 . The switch  114  alternately selects between the audio decoder  106  and the bypass route  112 , and supplies the PCM digital audio signal outputted by the selected one to the audio D/A converter  107 . With the configuration shown in  FIG. 7 , it is acceptable for the encoder  105  to not be able to modify the bit rate of audio encoding. 
         [0054]    Next, an example of operation of the video/audio processor  2  shown in  FIG. 7 , which is a video/audio processor  2  having a bypass route, will be described with reference to the flowchart shown in  FIG. 8 . 
         [0055]    Steps S 10  and S 20  are analogous to those in the flowchart shown in  FIG. 5 , and therefore a detailed description thereof is omitted. 
         [0056]    In a case in which no switch between the main part of a broadcast program and a CM has been detected, or in a case in which a switch between the main part of a broadcast program and a CM has been detected, but the difference in volume between the main part and the CM is less than the threshold (NO in Step S 20 ), the system returns to Step S 20 . 
         [0057]    On the other hand, in a case in which a switch between the main part of a broadcast program and a CM has been detected, and moreover the difference in volume between the main part and the CM is equal to or greater than the threshold (YES in Step S 20 ), the switches  113  and  114  perform selective switching (Step S 31 ), and thereafter return to Step S 20 . In a case of a switch from the main part of a broadcast program to a CM, the switch  113  switches from the bypass route  112  and selects the encoder  105 , and the switch  114  switches from the bypass route  112  and selects the audio decoder  106 . Conversely, in a case of a switch from a CM of a broadcast program to the main part, the switch  113  switches from the encoder  105  and selects the bypass route  112 , and the switch  114  switches from the audio decoder  106  and selects the bypass route  112 . 
         [0058]    In a case in which the switches  113  and  114  have not selected bypass route  112 , the sound quality of the analog audio signal may be poor due to degraded quality associated with audio encoding by the encoder  105 , and making it hard for the user to hear. Therefore the user may have the illusion that the volume is lower. Specifically, it is possible for the volume to appear lower in illusory fashion, with no actual lowering of the volume. 
         [0059]    While the present invention has been described in terms of the presently preferred embodiments, the present invention is not limited thereto, and addition of various modifications can be carried out without departing from the spirit of the invention. 
         [0060]    For example, a modification analogous to the modification from  FIG. 2  to  FIG. 7  can be performed on  FIG. 3  or  FIG. 4 . A modification analogous to the modification from  FIG. 5  to  FIG. 6  can be performed on  FIG. 8 . It is possible to eliminate any one or two steps among Steps S 21  to  23  from  FIG. 6 . 
         [0061]    Rather than providing the HDD-equipped optical disc recorder with a video D/A converter and audio D/A converter, it would be acceptable to instead provide a video D/A converter and audio D/A converter connected to output terminals of the HDD-equipped optical disc recorder. 
         [0062]    Additionally, the present invention can be implemented in a digital broadcast reception device other than an HDD-equipped optical disc recorder (for example, a TV receiver).