Patent Publication Number: US-2006001554-A1

Title: Video signal reception apparatus and video signal reception method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-193769, filed Jun. 30, 2004, the entire contents of which are incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a standardized digital transmission system for transmitting a digital video signal obtained by multiplexing digital audio signals and, more particularly, to a video signal reception apparatus and video signal reception method for receiving the digital video signal, and performing specific control for an audio signal system.  
      2. Description of the Related Art  
      As disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-128182, in recent years, a digital video device which receives and outputs a digital video signal has greatly prevailed. As is known well, a DVI (Digital Visual Interface) standard is widely used as a standard for transmitting the digital video signal. Also, recently, an HDMI (High Definition Multimedia Interface) standard is used as a digital signal transmission standard by further improving this DVI standard.  
      This HDMI standard includes various elements capable of, e.g., transmitting audio data by multiplexing digital audio signals during the blanking period of the digital video signal, transmitting the digital video signal in a color difference YCbCr format in addition to an RGB format, and connecting units via a USB (Universal Serial Bus)-like small HDMI connector. These elements are not included in the DVI standard.  
      Since the HDMI standard is versatile as described above, a device, display apparatus, and the like each having the HDMI connector will be widely used. However, when the digital transmission system complying with this HDMI standard is to be built, various elements which are not included in the transmission system complying with the DVI standard must be considered.  
      For example, while the digital audio signal can be transmitted according to the HDMI standard, an analog audio signal is transmitted in a system different from that of the digital audio signal according to the transmission system complying with the DVI standard. This leads to an increase in a product price and complicates a structure around a cable connection, when independently arranging the connectors complying with the HDMI standard and DVI standard.  
     BRIEF SUMMARY OF THE INVENTION  
      In the present invention, the video signal reception apparatus selects the analog audio signal from the audio information processing unit when the digital audio signal received via the HDMI connector is present, and selects the analog audio signal from the analog audio signal input unit when the digital audio signal is absent.  
      Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
      The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
       FIG. 1  is a block diagram showing the example of the schematic arrangement of a video signal reception apparatus;  
       FIG. 2  is a block diagram showing the example of the schematic arrangement of an HDMI signal processing unit in the video signal reception apparatus shown in  FIG. 1 ;  
       FIG. 3  is a flowchart for explaining the example of the operation of the video signal reception apparatus shown in  FIG. 1 ; and  
       FIG. 4  is a flowchart for explaining the example of the operation of the HDMI signal processing unit in the video signal reception apparatus shown in  FIG. 1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      An embodiment of the present invention will be described in detail below with reference to the accompanying drawing.  FIG. 1  is a block diagram showing the example of the schematic arrangement of a video signal reception apparatus  11  in the present invention. This video signal reception apparatus  11  includes functions of receiving a TV (television) broadcast signal, an analog video signal and analog audio signal, and a digital video signal complying with an HDMI standard.  
      That is, the TV broadcast signal is received by an antenna  12 , and then supplied to a TV signal processing unit  14  via a TV input terminal  13 . This TV signal processing unit  14  extracts a predetermined channel signal from the input TV broadcast signal by using a tuner unit  14   a,  reconstructs the analog video signal and analog audio signal by using a signal processing unit  14   b,  and then outputs the reconstructed signals to a selector  15 . The TV signal processing unit  14  can also receive a signal from, e.g., a CATV (Cable television) input terminal  13   b.    
      The analog video signal and analog audio signal are received by an AV (Audio Video) input terminal  16 , and directly output to the selector  15 .  
      The digital video signal and digital audio signal supplied from an external device  201  via an HDMI cable bus  18  complying with the HDMI standard are received by an HDMI connector  19 . As the external device  201 , an STB (Set-Top Box), DVD (Digital Video Disc) device, or the like having the HDMI connector complying with the HDMI standard is available. However, some devices realized before the HDMI standard has prevailed do not have the HDMI connectors.  
      A DVI-compatible device  202  can be connected to the HDMI connector  19  via a conversion cable bus  41 . The DVI-compatible device  202  is, e.g., a personal computer which includes a terminal  43  for outputting the digital video signal, and a terminal  44  for outputting the analog audio signal. Therefore, when the DVI-compatible device  202  is connected to the HDMI connector  19 , the conversion cable bus  41  is used, and the terminal  44  for outputting the analog audio signal is independently connected to an analog audio signal input terminal  46  via an analog audio cable  45 .  
      A signal output from the HDMI connector  19  is supplied to an HDMI signal processing unit  20 . This HDMI signal processing unit  20  (to be described later in detail) reconstructs the analog video signal and analog audio signal from the digital signal complying with the input HDMI standard, and outputs the reconstructed analog signals to the selector  15 .  
      Note that the analog audio signal is input to the selector  15  via a switch  21 . The switch  21  selects one of the analog audio signals from the HDMI signal processing unit  20  and the analog audio signal input terminal  46 . The selected analog audio signal is output to the selector  15 .  
      On the basis of the control signal from an audio detection unit  22 , the switch  21  is controlled. That is, the audio detection unit  22  determines whether the HDMI signal processing unit  20  processes the digital audio signal, and then the switch  21  is controlled on the basis of the determination result (control signal). If the digital audio signal is processed, the switch  21  selects the analog audio signal output from the HDMI signal processing unit  20 . If not, the switch  21  selects the analog audio signal from the analog audio signal input terminal  46 .  
      The selector  15  selectively switches between the analog video signal and analog audio signal output from the TV signal processing unit  14 , the analog video signal and analog audio signal supplied to the AV input terminal  16 , and the analog video signal and analog audio signal respectively output from the HDMI signal processing unit  20  and the switch  21 . The analog video signal is supplied to a video signal processing circuit  31 , and the analog audio signal is supplied to an audio signal processing circuit  33 . The output from the video signal processing circuit  31  is supplied to a display unit  32 , and the output from the audio signal processing circuit  33  is supplied to a loudspeaker system  34 .  
      In this video signal reception apparatus  11 , a control unit  23  totally controls all operations such as receiving of the above-described various signals. This control unit  23  includes a CPU (Central Processing Unit) and the like to receive operation information from an operation unit  24 , or operation information from a remote controller  25  via a reception unit  26 . The control unit  23  also controls the units to reflect the operation contents to these units.  
      In this case, the control unit  23  uses a memory unit  27 . That is, this memory unit  27  mainly includes a read-only memory which stores a control program to be executed by the CPU in the control unit  23 , a read/write memory which supplies a work area to this CPU, and a nonvolatile memory which stores various pieces of setting information and control information.  
       FIG. 2  is a block diagram showing the example of the schematic arrangement of the HDMI signal processing unit  20 . The HDMI cable bus  18  serving as a digital transmission bus complying with the HDMI standard mainly includes three types of lines called TMDS, DDC, and Power.  
      Of these lines, the line TMDS is used to transmit the digital video signal and digital audio signal complying with the HDMI standard, from the HDMI-compatible device  201  to the HDMI connector  19  in the video signal reception apparatus  11 . This line TMDS can also transmit the digital video signal from the DVI-compatible device  202 .  
      The line DDC is used to transmit control data, a synchronous clock, and the like between the HDMI-compatible device  201  and the video signal reception apparatus  11 .  
      The line Power is used to apply a constant voltage of, e.g., about 5 V from the HDMI-compatible device  201  to the HDMI connector  19 . In this case, the video signal reception apparatus  11  determines whether the HDMI-compatible device  201  is connected to the HDMI connector  19  by checking the voltage level of the line Power connecting to the HDMI connector  19 . That is, a constant voltage of, e.g., about 5 V from the HDMI-compatible device  201  serves as a connection recognition signal.  
      The digital signal complying with the HDMI standard, which is received via the HDMI connector  19  is supplied to an HDMI receiver  211 . This HDMI receiver  211  receives a signal in synchronism with the input digital signal, and outputs the received signal to a subsequent demultiplexing/conversion unit  212 . The demultiplexing/conversion unit  212  demultiplexes a video component from an audio component, and converts these components into respective signals respectively applying to the display system and the loudspeaker system.  
      The digital video signal output from the demultiplexing/conversion unit  212  is output to a video information processing unit  213 , and the digital audio signal from the demultiplexing/conversion unit  212  is output to an audio information processing unit  214 . In the video information processing unit  213 , MPEG (Moving Picture Experts Group) decoding processing is executed for the input video component, and the decoded output is output to a digital/analog conversion unit  215 . The digital/analog conversion unit  215  converts the output from the video information processing unit  213  into the analog video signal, and outputs the analog video signal via an output circuit  217 .  
      In the audio information processing unit  214 , for example, linear PCM (Pulse Code Modulation) decoding processing is executed for the input audio component, and the decoded output is output to a digital/analog conversion unit  216 . Alternatively, in the audio information processing unit  214 , Dolby-compatible processing, AC3-compatible processing, or MPEG-compatible processing is executed for the input audio component, and the decoded output is output to the digital/analog conversion unit  216 . The digital/analog conversion unit  216  converts the output from the audio information processing unit  214  into an analog audio signal, and outputs the analog audio signal via an output circuit  218 .  
      The HDMI signal processing unit  20  incorporates an HDMI control unit  221 . For example, the HDMI control unit  221  incorporates a microcomputer to reflect an instruction from the control unit  23  to the functions of the HDMI signal processing unit  20 . Additionally, the HDMI signal processing unit  20  can analyze the control data transmitted via the line DDC, and reflect the analysis result to the functions of the HDMI signal processing unit  20 .  
      When detecting the occurrence of change in the predetermined data in the received digital signal, the HDMI receiver  211  outputs the detection signal to an audio mute control unit (not shown). The HDMI control unit  221  monitors the voltage level of the line Power connecting to the HDMI connector  19 . When detecting the occurrence of change in the voltage level, the HDMI control unit  221  detects the insertion and extraction of the HDMI connector  19 , and outputs the detection signal to an audio mute control unit (not shown). The audio mute control unit outputs a mute signal to the digital/analog conversion unit  216  and the output circuit  218  on the basis of the detection signal from the HDMI receiver  211  or the HDMI control unit  221 .  
      The audio detection unit  22  may be included in the HDMI control unit  221 . This audio detection unit  22  detects whether the digital audio information is present in the audio information processing unit  214 . Alternatively, the audio detection unit  22  detects whether the digital audio information is present in the output level of the output circuit  218 . The presence of the digital audio information means that the digital audio signal is transmitted via the HDMI connector  19 . At this time, the audio detection unit  22  controls the switch  21  to select the output from the output circuit  218 . If the digital audio information is absent, the DVI-compatible device  202  may be connected to the HDMI connector  19  via the conversion cable bus  41  at a high possibility. Hence, the audio detection unit  22  controls the switch  21  to select the output from the analog audio signal input terminal  46 . With this processing, both the signal from the device having the HDMI connector complying with the HDMI standard, and the signal from the device having the connector complying with the DVI standard can be easily received.  
      As the method of detecting whether the digital audio signal is present, various methods are available. For example, the HDMI control unit  221  may determine the presence of the digital audio signal by, e.g., attribute information pertaining to the acquired audio signal. As the attribute information pertaining to audio data, the sampling frequency, channel count, and the like of the audio data are used. In addition to these, as the attribute information pertaining to the audio data, identification information representing the type of a compression scheme, and identification information representing a PCM scheme are available.  
       FIG. 3  is a flowchart showing the example of the operation of the video signal reception apparatus  11 . When a power supply is applied in step SA 1 , the control unit  23  specifies the selected reception function in step SA 2 .  
      In this case, when receiving the TV broadcast signal, the control unit  23  controls the TV signal processing unit  14  in step SA 3 . At this time, the control unit  23  also controls the selector  15  to select the analog video signal and analog audio signal output from the TV signal processing unit  14 , and the process ends.  
      Alternatively, when it is determined that the reception of the analog video signal and analog audio signal is selected in step SA 2 , the control unit  23  controls, in step SA 4 , the selector  15  to select the analog video signal and analog audio signal input to the AV input terminal  16 , and the process ends.  
      When it is determined that the reception of the digital video signal complying with the HDMI standard is selected in step SA 2 , the control unit  23  sets the operation of the HDMI signal processing unit  20  in step SA 5 , and controls the selector  15  to select the analog video signal and analog audio signal output from this HDMI signal processing unit  20 . Then, the process ends.  
      As the operation settings of the HDMI signal processing unit  20 , for example, the HDMI control unit  221  analyzes the compression scheme of the video signal, aspect ratio information, scanning line count information, pixel count information, field frequency information or frame frequency information in accordance with the control information transmitted via the HDMI connector  19 . The HDMI control unit  221  then sets block functions of the processing unit into processing states applying to these attributes. In the audio signal processing as well, the HDMI control unit  221  sets the audio processing system such that the block functions apply to these transmitted attributes.  
       FIG. 4  is a flowchart showing the example of the control operation of the HDMI signal processing unit  20  and the control unit  221  performed after the operation setting of the HDMI signal processing unit  20 .  
      When the operation of the HDMI signal processing unit  20  is not designated, the control unit  23  receives a response signal. Accordingly, a process shifts to another operation (step SB 2 ). When it is determined that the operation of the HDMI signal processing unit  20  is designated (step SB 1 ), it is determined that the digital audio signal is detected or not (step SB 3 ). If the digital audio signal is detected, the switch  21  is controlled to select the output from the output circuit  218  (step SB 4 ). Alternatively, when the digital audio signal is not detected, the switch  21  is controlled to select the output from the input terminal  46  (step SB 5 ).  
      Note that, in additional step SB 6 , it may be determined whether the analog audio signal is output, because a user may forget to connect the connection cable of the analog audio signal. When the analog audio signal is not detected, a warning message may be displayed, or an alarm sound may be output.  
      That is, the control unit  23  checks the input of the analog audio signal when the switch  21  selects the output from the analog audio signal input terminal  46 . When the analog audio signal is not input, the warning message is output. At the same time, the power supply of the audio signal processing system of the HDMI signal processing unit  20  may be turned off or switched to a low power state such that excessive power is not consumed.  
      Although the user may be mistaken to use a HDMI-compatible device as a DVI-compatible device, and connect the HDMI device to the video signal reception apparatus  11  via the conversion cable bus  41  and the analog audio cable, audio playback can be executed with no problem, since the HDMI-compatible device can also be connected to the conversion cable bus  41  and the HDMI connector  19  via analog audio cable.  
      In the above embodiment, for example, in addition to the audio detection unit  22 , a TV broadcast receiver using a CRT (Cathode Ray Tube), a TV broadcast receiver using a liquid crystal display, and a projection video display apparatus may serve as the video signal reception apparatus  11 .  
      Also, as an external device  17  which supplies the digital video signal complying with the HDMI standard to this video signal reception apparatus  11 , for example, a DVD (Digital Versatile Disk) player, D (digital)-VHS (Video Home System) recorder, set-top box, and digital video camera are available.  
      Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.