Abstract:
The present disclosure provides a receiving device including, a receiver that receives AV content, a detector, an acquirer, a tentative reservation registering part, and a definitive reservation registering part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/452,376, filed Apr. 20, 2012, which claims the benefit of priority of Provisional Application Ser. No. 61/480,033, filed Apr. 28, 2011, the entire contents of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present technique relates to receiving devices and methods, transmitting devices and methods, and programs, and particularly to receiving device and method, transmitting device and method, and program that enable assured download reservation of AV content. 
         [0003]    In recent years, due to dissemination of digital broadcasting, reception of multiple channels and high-definition television broadcasting has become general. 
         [0004]    Meanwhile, technique studying and system formulation for enabling not only normal television broadcasting but also more advanced broadcasting service required by viewers by utilizing the band that can be used in the digital broadcasting are being carried out. 
         [0005]    Functions required by viewers include on-demand viewing, which allows AV content to be viewed whenever a viewer wants to view it. However, it is considered difficult to realize the on-demand viewing in not broadcasting of bidirectional transmission but broadcasting of unidirectional transmission. 
         [0006]    So, in order to enable the on-demand viewing in the broadcasting of unidirectional transmission, studies are being made on the NRT service in which broadcast AV content is temporarily recorded in a storage and thereafter reproduced thereof on the premise that the receiving device holds the high-capacity storage (see Japanese Patent Laid-open No. 2011-41242, hereinafter referred to as Patent Document 1). 
         [0007]    The NRT (Non Real Time) service is not premised on viewing in real time. In this service, there is no need to view AV content in synchronization with the broadcast time of the AV content and AV content is transmitted as data by a broadcast signal. 
         [0008]    Specifically, in the NRT service, completion of recording (download) in a shorter time is possible if the transmission band of a signal with a broadcast wave is wider for example, differently from past recording reservation of AV content of a broadcast show. Or, download is completed in a longer time if the transmission band of a signal by a broadcast wave is narrower for example. 
       SUMMARY 
       [0009]    In the NRT service of the past, in the case of reserving download of AV content, information that is called NRT-IT (NRT Information Table) and relates to download of AV content transmitted in non-real time needs to be acquired in advance. In the NRT-IT, a list of AV content for which download reservation is possible is described. From the list, desired AV content is selected. 
         [0010]    The NRT-IT is periodically transmitted together with AV content. However, if the NRT-IT held by the receiving device is old, even AV content for which download reservation is possible essentially cannot be reserved and the download reservation must be awaited until the NRT-IT is updated. As a result, possibly the opportunity for the download reservation of the AV content is lost. 
         [0011]    The present technique is made in view of such circumstances and is to enable assured download reservation of AV content and widening of the opportunity for download reservation. 
         [0012]    A receiving device of one embodiment of the present technique includes a receiver that receives AV content, a detector that detects trigger information that is transmitted together with the AV content to be received and relates to control of an application program for being run in conjunction with the AV content, and an acquirer that acquires an application program for allowing selection of AV content for which download reservation is possible and that is transmitted in non-real time, based on the detected trigger information. The receiving device further includes a tentative reservation registering part that registers AV content selected based on the acquired application program as tentative reservation, and a definitive reservation registering part that registers the tentatively reserved AV content as definitive reservation if an identifier of AV content for which download reservation is possible, included in download information that is periodically transmitted together with the AV content and relates to download of AV content transmitted in non-real time, is identical to an identifier of the tentatively reserved AV content. 
         [0013]    The tentative reservation registering part registers selected AV content as tentative reservation if the download information is not recorded. 
         [0014]    The application program is content for allowing selection of AV content for which download reservation is possible and that is transmitted in non-real time based on a list. 
         [0015]    The receiving device further includes a controller that controls acquisition or activation of the application program or stop of the application program that is running, in accordance with a command indicated by the detected trigger information. 
         [0016]    The receiving device may be an independent device or may be an internal block configuring one device. 
         [0017]    A receiving method or a program of one embodiment of the present technique is a method or a program corresponding to the above-described receiving device of one embodiment of the present technique. 
         [0018]    In the receiving device and method and the program of one embodiment of the present technique, AV content is received, and trigger information that is transmitted together with the AV content to be received and relates to control of an application program for being run in conjunction with the AV content is detected. Based on the detected trigger information, an application program for allowing selection of AV content for which download reservation is possible and that is transmitted in non-real time is acquired. Furthermore, AV content selected based on the acquired application program is registered as tentative reservation. In addition, the tentatively reserved AV content is registered as definitive reservation if the identifier of AV content for which download reservation is possible, included in download information that is periodically transmitted together with the AV content and relates to download of AV content transmitted in non-real time, is identical to the identifier of the tentatively reserved AV content. 
         [0019]    A transmitting device of one embodiment of the present technique includes a trigger information generator that generates trigger information relating to control of an application program run in conjunction with AV content in a receiving device, a transmitter that transmits the generated trigger information together with the AV content, and a download information generator that generates download information relating to download of the AV content transmitted in non-real time. The transmitter periodically transmits the generated download information together with the AV content. 
         [0020]    At least one of commands to control acquisition or activation of an application program for allowing selection of AV content for which download reservation is possible and that is transmitted in non-real time or stop of the application program that is running is included in a command indicated by the trigger information. 
         [0021]    The transmitter multiplexes the trigger information into a transport stream corresponding to the AV content and transmits the trigger information. 
         [0022]    The transmitter stores the trigger information in an adaptation field of a packet configuring a transport stream corresponding to the AV content and transmits the trigger information. 
         [0023]    The transmitting device may be an independent device or may be an internal block configuring one device. 
         [0024]    A transmitting method or a program of one embodiment of the present technique is a method or a program corresponding to the above-described transmitting device of one embodiment of the present technique. 
         [0025]    In the transmitting device and method and the program of one embodiment of the present technique, trigger information relating to control of an application program run in conjunction with AV content in a receiving device is generated, and the generated trigger information is transmitted together with the AV content. Furthermore, download information relating to download of the AV content transmitted in non-real time is generated, and the generated download information is periodically transmitted together with the AV content. 
         [0026]    According to one embodiment of the present technique, the opportunity for download reservation of AV content can be widened. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a diagram showing a configuration example of a broadcasting system; 
           [0028]      FIG. 2  is a diagram showing a configuration example of a broadcasting device; 
           [0029]      FIG. 3  is a diagram showing a configuration example of a receiving device; 
           [0030]      FIG. 4  is a diagram showing the protocol stack of a signal of a broadcast wave; 
           [0031]      FIG. 5  is a diagram showing a configuration example of NRT-IT; 
           [0032]      FIG. 6  is a state transition diagram of an application program; 
           [0033]      FIGS. 7A and 7B  are diagrams for explaining an example in which trigger information is multiplexed into a transport stream; 
           [0034]      FIG. 8  is a diagram showing a concept that trigger information is so transmitted as to be included in a PCR packet of TS; 
           [0035]      FIG. 9  is a flowchart for explaining AV content transmission processing; 
           [0036]      FIG. 10  is a flowchart for explaining AV content reception processing; 
           [0037]      FIG. 11  is a flowchart for explaining the AV content reception processing; 
           [0038]      FIG. 12  is a diagram showing a configuration example of TDO content; 
           [0039]      FIG. 13  is a diagram showing a display example of a list of AV content permitted to be tentatively reserved; and 
           [0040]      FIG. 14  is a diagram showing a configuration example of a computer. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0041]    An embodiment of the present technique will be described below with reference to the drawings. 
       [Configuration of Broadcasting System] 
       [0042]      FIG. 1  is a diagram showing a configuration example of a broadcasting system. 
         [0043]    A broadcasting system  1  is composed of a broadcasting device  11 , a receiving device  13 , and a content delivery server  18 . 
         [0044]    The broadcasting device  11  is set at a broadcasting station. The broadcasting device  11  transmits AV content of e.g. show, CM, etc. as a digital television broadcast signal. The digital television broadcast signal is transmitted as normal broadcasting and NRT broadcasting. 
         [0045]    The normal broadcasting is broadcasting premised on viewing in real time in the receiving device  13  into which this broadcast signal is received. Furthermore, the NRT broadcasting is not premised on viewing in real time. In the NRT broadcasting, there is no need to view AV content at the broadcast time of the AV content, and the AV content is transmitted as data by a broadcast signal. 
         [0046]    Furthermore, the broadcasting device  11  transmits trigger information as a command for ordering execution of data broadcasting content executed in association with the progression of AV content of a show, etc. in such a manner that the trigger information is included in the digital television broadcast signal. This trigger information includes, in addition to information indicating the kind of command, data broadcasting content, i.e. information indicating the acquisition source of the data broadcasting content, and so forth. Details of the trigger information will be described later. 
         [0047]    In addition, the broadcasting device  11  periodically transmits information relating to download of AV content transmitted in non-real time in the NRT broadcasting (hereinafter, referred to as download information) together with AV content. As the download information, e.g. the above-described NRT-IT is present. Details thereof will be described later. 
         [0048]    The digital television broadcast signal transmitted from the broadcasting device  11  is received by the receiving device  13  by way of a relay station  12 . 
         [0049]    The receiving device  13  is set at a user&#39;s house for example. If the receiving device  13  receives a digital television broadcast signal of the normal broadcasting, the receiving device  13  makes AV content obtained from the digital television broadcast signal be displayed on a display  13 A and viewed. 
         [0050]    Furthermore, if download of AV content is reserved, the receiving device  13  starts reception of a digital television broadcast signal of the NRT broadcasting at the broadcast start time of the reserved AV content, and records the AV content obtained from the digital television broadcast signal in a storage  14 . Moreover, the receiving device  13  reads out the AV content recorded in the storage  14  and reproduces it to thereby make the AV content broadcast by the NRT broadcasting be viewed. 
         [0051]    In addition, the receiving device  13  is connected to a LAN (Local Area Network)  15  and can connect to the Internet  17  via a router  16 . If trigger information is obtained from a digital television broadcast signal, the receiving device  13  connects to the content delivery server  18  via the Internet  17  based on the acquisition source of data broadcasting content included in the trigger information and acquires the data broadcasting content. The data broadcasting content is not limited by the method of acquiring it via the Internet  17  and may be acquired from a multiplexed stream obtained by demodulating a digital television broadcast signal for example. 
         [0052]    The receiving device  13  registers tentative reservation of AV content based on the acquired data broadcasting content and then registers definitive reservation of the tentatively reserved AV content based on the download information periodically transmitted from the broadcasting device  11 . Details of download reservation by use of data broadcasting content (TDO content to be described later) will be described later. 
         [0053]    The content delivery server  18  is set at a broadcasting station or the like. The content delivery server  18  generates data broadcasting content for presenting a list of AV content for which download reservation is possible in the NRT broadcasting. The content delivery server  18  delivers data broadcasting content via the Internet  17  in response to an acquisition request from the receiving device  13 . 
         [0054]    The broadcasting system  1  is configured in the above-described manner. 
         [0055]    The data broadcasting content is realized through running of an application program supplied to the receiving device  13  by a computer in the receiving device  13 . Therefore, hereinafter, the data broadcasting content will be referred to also as data broadcasting application program or data broadcasting application. 
       [Configuration of Broadcasting Device] 
       [0056]      FIG. 2  is a diagram showing a configuration example of a broadcasting device. 
         [0057]    The broadcasting device  11  is composed of a video encoder  31 , an audio encoder  32 , a multiplexer  33 , a trigger generator  34 , a download information generator  35 , and a sender  36 . 
         [0058]    The video encoder  31  encodes the video stream of AV content of a show, etc. input from the previous stage in accordance with a predetermined encoding system and supplies the encoded video stream obtained as the result to the multiplexer  33 . Examples of the encoding system in the video encoder  31  include MPEG2 (Moving Picture Experts Group phase 2) system and H.264 system. 
         [0059]    The audio encoder  32  encodes the audio stream corresponding to the video stream input to the video encoder  31  in accordance with a predetermined encoding system and supplies the encoded audio stream obtained as the result to the multiplexer  33 . Examples of the encoding system in the audio encoder  32  include AC3 (Audio Code number 3) system and AAC (Advanced Audio Coding) system. 
         [0060]    The trigger generator  34  generates trigger information in association with the progression of the video stream of AV content input from the previous stage and supplies it to the multiplexer  33 . 
         [0061]    The download information generator  35  periodically generates download information such as NRT-IT based on information relating to AV content for which download reservation is possible, and supplies it to the multiplexer  33 . 
         [0062]    To the multiplexer  33 , the encoded video stream from the video encoder  31 , the encoded audio stream from the audio encoder  32 , the trigger information from the trigger generator  34 , and the download information from the download information generator  35  are supplied. 
         [0063]    The multiplexer  33  multiplexes the encoded video stream and the encoded audio stream and multiplexes also the trigger information to supply the multiplexed stream obtained as the result to the sender  36 . Specifically, the multiplexer  33  multiplexes the streams into e.g. TS (transport stream). Alternatively, in consideration of network delivery of digital television broadcasting, the multiplexer  33  may multiplex the streams into the ISO base media file format (MP4) suitable for it. 
         [0064]    Furthermore, if the download information is supplied from the download information generator  35 , the multiplexer  33  multiplexes the download information into the multiplexed stream. 
         [0065]    The sender  36  sends out the multiplexed stream supplied from the multiplexer  33  as a digital television broadcast signal. 
         [0066]    The broadcasting device  11  is configured in the above-described manner. 
       [Configuration of Receiving Device] 
       [0067]      FIG. 3  is a diagram showing a configuration example of the receiving device. 
         [0068]    The receiving device  13  is composed of a tuner  51 , a demultiplexer  52 , a video decoder  53 , a video output part  54 , an audio decoder  55 , an audio output part  56 , a trigger detector  57 , a controller  58 , a memory  59 , an operation part  60 , a communication I/F  61 , a cache memory  62 , an application engine  63 , a download information detector  64 , and a download reservation unit  65 . 
         [0069]    The tuner  51  receives and demodulates a digital television broadcast signal corresponding to the channel selected by the user and supplies the multiplexed stream obtained as the result to the demultiplexer  52 . 
         [0070]    The demultiplexer  52  separates the multiplexed stream supplied from the tuner  51  and supplies the separated encoded video stream and encoded audio stream to the video decoder  53  and the audio decoder  55 , respectively. Furthermore, if trigger information or download information transmitted together with the multiplexed stream is detected, the demultiplexer  52  supplies the trigger information and the download information to the trigger detector  57  and the download information detector  64 , respectively. 
         [0071]    The video decoder  53  decodes the encoded video stream from the demultiplexer  52  and supplies the video signal obtained as the result to the video output part  54 . 
         [0072]    The video output part  54  outputs the video signal supplied from the video decoder  53  to the subsequent stage (e.g. display  13 A). Furthermore, the video output part  54  combines a video signal of a data broadcasting application program (hereinafter, referred to as data broadcasting application) supplied from the application engine  63  and the video signal supplied from the video decoder  53 , and outputs the resulting signal to the subsequent stage. 
         [0073]    The audio decoder  55  decodes the encoded audio stream from the demultiplexer  52  and supplies the audio signal obtained as the result to the audio output part  56 . 
         [0074]    The audio output part  56  outputs the audio signal supplied from the audio decoder  55  to the subsequent stage (e.g. speaker). 
         [0075]    The trigger detector  57  detects trigger information from the multiplexed stream separated by the demultiplexer  52  and supplies it to the controller  58 . 
         [0076]    The controller  58  runs a control program recorded in the memory  59  to thereby control the operation of the respective parts of the receiving device  13 . Furthermore, the controller  58  controls acquisition, activation, event firing, suspension, stop, and so forth of the data broadcasting application based on the trigger information supplied from the trigger detector  57 . 
         [0077]    The operation part  60  accepts various kinds of operation from the user and notifies the controller  58  of an operation signal corresponding to it. 
         [0078]    The communication I/F  61  connects to the content delivery server  18  via the Internet  17  in accordance with control from the application engine  63 . The application engine  63  acquires a data broadcasting application from the content delivery server  18  via the communication I/F  61  and the Internet  17  and makes the cache memory  62  retain it in accordance with control from the controller  58 . 
         [0079]    The application engine  63  reads out and runs the data broadcasting application retained in the cache memory  62  in accordance with control from the controller  58 . 
         [0080]    The download information detector  64  detects download information from the multiplexed stream separated by the demultiplexer  52  and supplies it to the controller  58 . 
         [0081]    The controller  58  analyzes the download information supplied from the download information detector  64  and records the analysis result in the memory  59 . 
         [0082]    The download reservation unit  65  executes processing relating to download reservation of AV content in accordance with control from the controller  58 . The download reservation unit  65  is composed of a tentative reservation registering part  71  and a definitive reservation registering part  72 . 
         [0083]    The tentative reservation registering part  71  registers desired AV content selected through running of the data broadcasting application as tentative reservation in accordance with control from the controller  58 . 
         [0084]    If the identifier of AV content included in the download information analyzed by the controller  58  is identical to the identifier of AV content tentatively reserved by the tentative reservation registering part  71 , the definitive reservation registering part  72  registers the tentatively reserved AV content as definitive reservation in accordance with control from the controller  58 . 
         [0085]    When the present time has become the broadcast start time of the AV content for which definitive reservation is registered, the download reservation unit  65  controls the tuner  51  to download the AV content of a predetermined channel. The multiplexed stream received by the tuner  51  and demodulated is separated by the demultiplexer  52  and recorded in the storage  14 . If the AV content is acquired from a delivery server connected to the Internet  17 , when the present time has become the reservation start time of the AV content for which definitive reservation is registered, the download reservation unit  65  controls the communication I/F  61  to download the AV content of a predetermined channel. The AV content received by the communication I/F  61  is recorded in the storage  14 . 
         [0086]    If reproduction of AV content recorded in the storage  14  is ordered, the video decoder  53  reads out and decodes the encoded video stream recorded in the storage  14  and outputs the video signal obtained as the result to the subsequent stage via the video output part  54 . Furthermore, the audio decoder  55  reads out and decodes the encoded audio stream recorded in the storage  14  and outputs the audio signal obtained as the result to the subsequent stage via the audio output part  56 . 
         [0087]    The receiving device  13  is configured in the above-described manner. 
       [Details of NRT Broadcasting] 
       [0088]    Next, details of the NRT broadcasting will be described below. In the NRT broadcasting, the following two systems exist: a system in which the user selects individual AV content and thereafter the AV content is received and accumulated (hereinafter, referred to as Pull-type NRT broadcasting); and a system in which the user registers viewing of a set of specified pieces of AV content and thereafter the receiving device  13  automatically receives and accumulates these pieces of AV content (hereinafter, referred to as Push-type NRT broadcasting). 
         [0089]    Here, the Pull-type NRT broadcasting will be described below. 
         [0090]      FIG. 4  is a diagram showing the protocol stack in a signal of a broadcast wave including the NRT broadcasting and the normal broadcasting. 
         [0091]    As shown in  FIG. 4 , the lowermost hierarchical level is used as Physical Layer (physical layer) and the frequency band of the broadcast wave allocated for this channel corresponds to this. The upper hierarchical level adjacent to Physical Layer is used as TS (transport stream). 
         [0092]    In TS, a packet of the upper hierarchical level is so transmitted as to be divided into a fixed-length packet called transport packet, and a series of this transport packet serves as a transport stream. That is, signals transmitted in the frequency band corresponding to one broadcast channel are all transmitted by the transport packet having header information corresponding to this broadcast channel and so forth. 
         [0093]    The upper hierarchical level adjacent to the transport stream is used as Section or PES (Packetized Elementary Stream). For example, data reproduced in real time like AV content of the normal broadcasting is transmitted as a packet of PES. Furthermore, data of file transfer, data of control information, and so forth are transmitted as a packet of Section. 
         [0094]    As shown in  FIG. 4 , corresponding to the kind of packet of PES, Caption Coding, Audio Coding, and Video Coding are defined as the upper hierarchical level of PES. Caption Coding is a packet in which data relating to a caption of an image is stored. Audio Coding is a packet in which audio data is stored. Video Coding is a packet in which image data is stored. 
         [0095]    As the upper hierarchical level adjacent to Section, PSIP and PSI are defined. PSIP (Program and System Information Protocol) is defined as a hierarchical level having VCT, NRT-IT, and so forth. The data of this PSIP is so configured as to include VCT, NRT-IT, and so forth and is periodically received by the receiving device  13 . PSI (Program Specific Information) is defined as a hierarchical level having PAT (Program Association Table), PMT (Program Map Table), and so forth. 
         [0096]    Furthermore, as the upper hierarchical level adjacent to Section, DSM-CC (Digital Storage Media Command and Control) is displayed. DSM-CC is used as an adaptation layer for transmitting an IP packet on MPEG2-TS of a broadcast stream. DSM-CC is defined as the ISO standard. 
         [0097]    As the upper hierarchical level adjacent to DSM-CC, Interactive Data Coding is displayed. Streaming broadcasting is realized by the data stored in Interactive Data Coding, Caption Coding, Audio Coding, and Video Coding. That is, by receiving these data, a show of the normal broadcasting can be received and reproduced. 
         [0098]    Furthermore, as the upper hierarchical level adjacent to DSM-CC, IP is displayed. IP displayed here is the same as IP in the protocol stack of TCI/IP and an IP packet is specified by the IP address. The NRT broadcasting is configured by using the IP packet. Of course, the NRT broadcasting is offered as not communication but broadcasting. Therefore, essentially the protocol stack of TCl/IP, which is a communication protocol, does not have to be used. However, the IP packet is formally used in download of AV content. 
         [0099]    The upper hierarchical level adjacent to IP is used as UDP and FLUTE/ALC (Asynchronous Layered Coding Protocol)/LCT (Layered Coding Transport (Building Block)) is displayed as the upper hierarchical level thereof. Specifically, in the NRT broadcasting, a packet in which a UDP port in TCP/IP communication is specified is transmitted, and a session by FLUTE (File Delivery over Unidirectional Transport) is established for example. Details of FLUTE are defined as RFC3926. 
         [0100]      FIG. 5  is a diagram showing an example of NRT-IT. 
         [0101]    The NRT-IT (NRT Information Table) is a table configured with descriptors for enabling identification of each piece of AV content of the NRT broadcasting, broadcast on each channel, in the receiving device  13 . 
         [0102]    As shown in  FIG. 5 , in the NRT-IT, information relating to download of each piece of AV content is described in the description area of each piece of AV content. In the example of  FIG. 5 , for each of Content#1, Content#2, . . . , Content#N, information such as Content ID, Distribution start/end, Content name, and Content URL is described in the description area thereof. 
         [0103]    As Content ID, an ID for identification of the AV content is described. This ID is described with predetermined characters, numerals, etc. 
         [0104]    As Distribution start/end, information relating to the delivery schedule of the AV content is described. As the delivery schedule, information representing the broadcast start time and broadcast end time of the AV content is described. Because the AV content is AV content of the NRT broadcasting, not the time during which the AV content can be viewed but the time when download of the AV content should be started and the time when the download should be ended are represented by the broadcast start time and the broadcast end time. 
         [0105]    As Content name, information relating to the name of the AV content is described. As this name, the title of the AV content is described by a character string, numerals, etc. for example. 
         [0106]    As Content URL, information relating to URL (Uniform Resource Locator) for specifying the place where the AV content is disposed is described. 
         [0107]    In this manner, Distribution start/end, Content name, and Content URL are described in the description area of the NRT-IT as information relating to the AV content identified by Content ID, and the NRT-IT in which these pieces of information are described is transmitted as download information. 
         [0108]    It is also possible to describe e.g. information relating to the version and expiration date of the AV content and so forth in the description area of the NRT-IT. 
         [0109]    The NRT-IT is configured in the above-described manner. 
         [0110]    About this NRT-IT, a description is given in e.g. patent document 1 (Japanese Patent Laid-open No. 2011-41242), which is an application by the present assignee. 
       [Details of Trigger Information] 
       [0111]    Next, details of trigger information will be described below. The trigger information is information for controlling a data broadcasting application. In this trigger information, commands of e.g. pre-cache, execute, inject event, suspend, and terminate are included. 
         [0112]    The pre-cache command (Pre-cache) is a command for ordering acquisition of a data broadcasting application. Furthermore, the execute command (Execute) is a command for ordering activation of a data broadcasting application. Moreover, the inject event command (Inject_event) is a command for firing an event in the running data broadcasting application. 
         [0113]    The suspend command (Suspend) is a command for suspending the running data broadcasting application. Furthermore, the terminate command (Terminate) is a command for stopping the running data broadcasting application. 
         [0114]      FIG. 6  is a state transition diagram of a data broadcasting application that operates in the receiving device  13  in response to the respective commands of pre-cache, execute, inject event, suspend, and terminate. 
         [0115]    As shown in  FIG. 6 , it is defined that the state of the data broadcasting application has transitioned to one of four kinds of states, i.e. stopped state (Stopped), ready state (Ready), active state (Active), and suspended state (Suspended). 
         [0116]    The stopped state refers to the state in which the data broadcasting application has not yet been acquired into the receiving device  13 . The ready state refers to the state in which the data broadcasting application has been acquired into the receiving device  13  and is not activated. The active state refers to the state in which the data broadcasting application is activated and running. The suspended state refers to the state in which the execution of the data broadcasting application is interrupted and information indicating the state of the interruption timing is retained in a save memory. 
         [0117]    When the data broadcasting application has transitioned to the stopped state (has not yet been acquired into the receiving device  13 ), transition to the ready state occurs if trigger information of the pre-cache command is received and the data broadcasting application is acquired in accordance with the pre-cache command. 
         [0118]    When the data broadcasting application is in the ready state, transition to the active state occurs if trigger information of the execute command is received and the data broadcasting application is activated in accordance with the execute command. 
         [0119]    Furthermore, when the data broadcasting application has transitioned to the stopped state (has not yet been acquired into the receiving device  13 ), transition to the active state occurs if trigger information of the execute command is received and the data broadcasting application is acquired and activated in accordance with the execute command. 
         [0120]    When the data broadcasting application has transitioned to the active state, transition to the suspended state occurs if trigger information of the suspend command is received and the running data broadcasting application is interrupted in accordance with the suspend command. 
         [0121]    When the data broadcasting application has transitioned to the suspended state, transition to the active state occurs if trigger information of the execute command is received and the interrupted data broadcasting application is resumed in accordance with the execute command. 
         [0122]    When the data broadcasting application has transitioned to the ready state, the active state, or the suspended state, transition to the stopped state occurs if trigger information of the terminate command is received and the running data broadcasting application is stopped in accordance with the terminate command. 
         [0123]    The state of the data broadcasting application transitions in the above-described manner. 
         [0124]      FIGS. 7A and 7B  show the case in which trigger information is multiplexed into TS. 
         [0125]    In this case, the descriptor of the trigger information is defined in the PMT (Program Map Table) descriptor of the TS as shown in  FIG. 7A  and the trigger information is described as shown in  FIG. 7B . Specifically, the syntax of the trigger information is described at a position subsequent to descriptor_length in  FIG. 7B . 
         [0126]    The descriptor of the trigger information may be defined in not the PMT descriptor but e.g. the SIT (selection information table) descriptor. 
         [0127]      FIG. 8  shows the concept of the case in which trigger information is so transmitted as to be disposed in a PCR (Program Clock Reference) packet of the TS of a digital television broadcast signal. 
         [0128]    As shown in  FIG. 8 , the trigger information is not stored in all PCR packets but stored in the PCR packet only at the proper timing for linkage to AV content. The PCR packet is a TS packet with adaptation_field in which PCR is stored. The trigger information is stored in transport_private data byte following PCR. 
         [0129]    In  FIGS. 7A ,  7 B and  FIG. 8 , the example in which trigger information is so transmitted as to be multiplexed into TS and the example in which trigger information is so transmitted as to be stored in PCR are shown. However, the method for storing and transmitting trigger information is not limited thereto. As another method, trigger information may be buried in video information itself for example. Furthermore, although pre-cache, execute, inject event, suspend, and terminate are described as one example of the command of trigger information, it is also possible to use other commands. 
         [0130]    Moreover, about this trigger information, a description is given in e.g. Japanese Patent Application No. 2011-041801 (filing date: Feb. 28, 2011), which is an application by the present assignee. 
       [Flow of AV Content Transmission Processing] 
       [0131]    Next, with reference to a flowchart of  FIG. 9 , AV content transmission processing executed by the broadcasting device  11  will be described below. 
         [0132]    In a step S 11 , the video encoder  31  encodes the video stream of AV content of a show, etc. input from the previous stage and supplies the encoded video stream obtained as the result to the multiplexer  33 . 
         [0133]    In a step S 12 , the audio encoder  32  encodes an audio stream input from the previous stage and supplies the encoded audio stream obtained as the result to the multiplexer  33 . 
         [0134]    In a step S 13 , the trigger generator  34  determines whether or not to transmit trigger information. If it is determined in the step S 13  that trigger information is to be transmitted, the processing proceeds to a step S 14 . 
         [0135]    In the step S 14 , the trigger generator  34  generates trigger information associated with the progression of the video stream of the AV content input from the previous stage. On the other hand, if it is determined in the step S 13  that trigger information is not to be transmitted, the step S 14  is skipped and the processing proceeds to a step S 15 . 
         [0136]    In the step S 15 , the download information generator  35  determines whether or not to transmit NRT-IT (download information). If it is determined in the step S 15  that NRT-IT is to be transmitted, the processing proceeds to a step S 16 . 
         [0137]    In the step S 16 , the download information generator  35  generates NRT-IT based on information relating to AV content for which download reservation is possible. On the other hand, if it is determined in the step S 16  that NRT-IT is not to be transmitted, the step S 16  is skipped and the processing proceeds to a step S 17 . 
         [0138]    In the step S 17 , the multiplexer  33  generates a multiplexed stream and supplies it to the sender  36 . 
         [0139]    Specifically, in the multiplexer  33 , the encoded video stream and the encoded audio stream are multiplexed. In addition, trigger information is also multiplexed if the trigger information is transmitted. Moreover, NRT-IT is also multiplexed if the NRT-IT is transmitted. 
         [0140]    In a step S 18 , the sender  36  sends out the multiplexed stream supplied from the multiplexer  33  as a digital television broadcast signal. Thereafter, the processing returns to the step S 11  and the above-described subsequent processing is repeated. 
         [0141]    In the above-described manner, in the broadcasting device  11 , in transmission of AV content, trigger information or NRT-IT is generated at a predetermined timing and transmitted together with the AV content. 
       [Flow of AV Content Reception Processing] 
       [0142]    Next, with reference to  FIG. 10  and  FIG. 11 , AV content reception processing executed by the receiving device  13  will be described below. 
         [0143]    In a step S 31 , the tuner  51  receives and demodulates a digital television broadcast signal corresponding to the channel selected by the user to supply the resulting signal to the demultiplexer  52 . 
         [0144]    In a step S 32 , the demultiplexer  52  separates the multiplexed stream from the tuner  51  and supplies the separated encoded video stream and encoded audio stream to the video decoder  53  and the audio decoder  55 . Furthermore, if trigger information or NRT-IT transmitted together with the multiplexed stream is detected, the demultiplexer  52  supplies the trigger information and the NRT-IT to the trigger detector  57  and the download information detector  64 , respectively. 
         [0145]    In a step S 33 , the video decoder  53  decodes the encoded video stream separated by the demultiplexer  52  and outputs the video signal obtained as the result to the display  13 A via the video output part  54 . 
         [0146]    In a step S 34 , the audio decoder  55  decodes the encoded audio stream separated by the demultiplexer  52  and outputs the audio signal obtained as the result to a speaker (not shown) via the audio output part  56 . 
         [0147]    Thereby, the AV content transmitted from the broadcasting device  11  is received and viewed by the user. 
         [0148]    In a step S 35 , the trigger detector  57  determines whether or not trigger information is detected from the multiplexed stream separated by the demultiplexer  52 . 
         [0149]    If it is determined in the step S 35  that trigger information is detected, the processing proceeds to a step S 36 . In the step S 36 , the controller  58  analyzes the command indicated by the detected trigger information. 
         [0150]    In a step S 37 , the controller  58  determines whether or not the analyzed command is Pre-cache. If it is determined in the step S 37  that the command is Pre-cache, the processing proceeds to a step S 38 . 
         [0151]    In the step S 38 , the application engine  63  acquires data of TDO content as the data broadcasting application specified by App_id of this trigger information in accordance with control from the controller  58 . This TDO content is acquired from the content delivery server  18  and retained in the cache memory  62 . App_id is identification information of the data broadcasting application that should be acquired corresponding to this trigger information. 
         [0152]    Subsequently, in a step S 39 , it is determined whether or not the command is Execute. For example, if the analyzed command is Pre-cache (“No” of the step S 39 ), the processing returns to the step S 31  and the above-described processing is repeated. Subsequently, if trigger information is detected (“Yes” of the step S 35 ) again and it is determined that the command is Execute (“Yes” of the step S 39 ), the processing proceeds to a step S 40 . 
         [0153]    In the step S 40 , the application engine  63  activates the TDO content retained in the cache memory  62  as the data broadcasting application specified by App_id in accordance with control from the controller  58 . 
         [0154]    If program data of the data broadcasting application specified by App_id has not yet been acquired (does not exist in the cache memory  62 ), the application engine  63  acquires and then activates it. Furthermore, if a currently-running data broadcasting application exists, the application engine  63  stops it and thereafter activates the TDO content. 
         [0155]    In a step S 41 , the application engine  63  determines whether or not information relating to download of AV content permitted to be tentatively reserved (hereinafter, referred to as tentative reservation download information) is included in the TDO content. In the TDO content, e.g. tentative reservation download information shown in  FIG. 12  is described. 
         [0156]      FIG. 12  is a diagram showing a configuration example of the TDO content. 
         [0157]    As shown in  FIG. 12 , the TDO content is described based on HTML (HyperText Markup Language). 
         [0158]    One or more item elements are described between the start tag and the end tag of the tdo element. The respective item elements are composed of content name element, content ID element, and content url element. 
         [0159]    The content name element is an element for describing the name of AV content. In the example of  FIG. 12 , “sportsnews10thApril” is described. 
         [0160]    The content ID element is an element for describing the ID to identity AV content. In the example of  FIG. 12 , “01234567” is described. 
         [0161]    The content url element is an element for describing URL to specify the place where AV content is disposed. In the example of  FIG. 12 , “http://www.abc.com/NRT/sportsnews/940822.mp4” is described. 
         [0162]    In this manner, in the TDO content, ID, name, and URL are described for each piece of AV content as the tentative reservation download information for identifying AV content permitted to be tentatively reserved. 
         [0163]    In the example of  FIG. 12 , the tentative reservation download information of one piece of AV content is described as a representative. If there are two or more pieces of AV content permitted to be tentatively reserved, the tentative reservation download information corresponding to that is described based on item element. Furthermore, it is enough that information that enables AV content to be uniquely identified is included in the tentative reservation download information. Therefore, it is not necessary that information of all of ID, name, and URL is included. Furthermore, other pieces of identification information may be used. Moreover, tags other than the tags of tdo element and item element may be used. 
         [0164]    Referring back to the flowchart of  FIG. 10 , if it is determined in the step S 41  that tentative reservation download information is included, the processing proceeds to a step S 42 . In the step S 42 , the application engine  63  supplies the tentative reservation download information to the video output part  54  and makes the display  13 A display it. For example, a list of AV content permitted to be tentatively reserved, like that shown in  FIG. 13 , is displayed on the display  13 A. 
         [0165]    Referring back to the flowchart of  FIG. 10 , in a step S 43 , the controller  58  determines whether or not desired AV content is selected based on operation of the operation part  60  by the user. If it is determined in the step S 43  that desired AV content is selected, the processing proceeds to a step S 44  in  FIG. 11 . 
         [0166]    On the other hand, if it is determined in the step S 43  that desired AV content is not selected, the processing returns to the step S 31  and the above-described processing is repeated. If trigger information is not detected (“No” of the step S 35 ) or if tentative reservation download information is not included in the TDO content (“No” of the step S 41 ), desired AV content is not selected. Thus, the processing returns to the step S 31  and the above-described processing is repeated. 
         [0167]    In the step S 44  in  FIG. 11 , the controller  58  determines whether or not NRT-IT periodically transmitted together with AV content is recorded in the memory  59 . If it is determined in the step S 44  that NRT-IT is not recorded, the processing proceeds to a step S 45 . For example, if the NRT-IT periodically transmitted from the broadcasting device  11  is not received due to radio interference and acquisition imperfection (reception miss) in the receiving device  13 , old NRT-IT remains recorded in the broadcasting device  11 . 
         [0168]    In the step S 45 , the tentative reservation registering part  71  registers tentative reservation of the selected desired content in accordance with control from the controller  58 . At this timing, because the reservation is tentative, the tentative reservation registration does not ensure that download will be surely performed. 
         [0169]    Subsequently, in the receiving device  13 , if new NRT-IT is transmitted from the broadcasting device  11 , the NRT-IT is received and detected by the download information detector  64  (step S 46 ). In a step S 47 , the controller  58  analyzes the newly received NRT-IT. 
         [0170]    In a step S 48 , the controller  58  determines whether or not the identifier of AV content included in the NRT-IT is identical to the identifier of the tentatively reserved AV content based on the analysis result of the newly received NRT-IT. 
         [0171]    In this determination processing, for example it is determined whether or not Content ID described in the NRT-IT (download information) ( FIG. 5 ) is identical to the ID of the tentatively reserved AV content, described in the content ID element of the TDO content (tentative reservation download information) ( FIG. 12 ). Furthermore, it is also possible to execute the determination processing by use of not only Content ID but other pieces of identification information such as Content name and Content URL that are information common to the NRT-IT of  FIG. 5  and the TDO content of  FIG. 12 . 
         [0172]    If it is determined in the step S 48  that the identifiers are identical, the processing proceeds to a step S 49 . 
         [0173]    In the step S 49 , the controller  58  determines whether or not the tentatively reserved AV content is downloadable and viewable. If it is determined in the step S 49  that the tentatively reserved AV content is downloadable and viewable, the processing proceeds to a step S 50 . 
         [0174]    In the step S 50 , the definitive reservation registering part  72  registers the tentatively reserved AV content as definitive reservation in accordance with control from the controller  58 . 
         [0175]    Specifically, if NRT-IT is not recorded, temporarily the selected desired AV content is registered as tentative reservation. Subsequently, when NRT-IT is newly received, the desired AV content tentatively reserved is registered as definitive reservation if the identifier of AV content included in the NRT-IT is identical to the identifier of the desired AV content tentatively reserved. 
         [0176]    Furthermore, if it is determined in the step S 44  that NRT-IT is recorded, the processing proceeds to the step S 47 . Subsequently, in the step S 47 , the controller  58  analyzes the recorded NRT-IT and determines whether or not the identifier of AV content included in the NRT-IT is identical to the identifier of the selected desired AV content based on the analysis result (step S 48 ). If it is determined in the step S 48  that the identifiers of AV content are identical, the processing proceeds to the step S 49 . 
         [0177]    Subsequently, if this AV content is downloadable and viewable (“Yes” of the step S 49 ), the definitive reservation registering part  72  registers the selected desired AV content as definitive reservation in accordance with control from the controller  58  in the step S 50 . 
         [0178]    That is, if NRT-IT is recorded, tentative reservation of the selected desired AV content is not registered and directly this AV content is registered as definitive reservation if the identifier of this AV content is identical to the identifier of AV content included in the NRT-IT. 
         [0179]    If it is determined in the step S 48  that the identifier of AV content included in the NRT-IT is not identical to the identifier of this AV content, the processing proceeds to a step S 51 . In the step S 51 , the controller  58  determines whether or not the AV content has been tentatively reserved. If it is determined in the step S 51  that the AV content has not been tentatively reserved, the tentative reservation registering part  71  registers tentative reservation of the AV content in accordance with control from the controller  58  (step S 52 ). On the other hand, if it is determined in the step S 51  that the AV content has been tentatively reserved, the step S 52  is skipped and the processing proceeds to a step S 53 . Subsequently, if new NRT-IT is transmitted from the broadcasting device  11 , the NRT-IT is received in the receiving device  13  (step S 53 ). 
         [0180]    If tentative reservation has been registered (step S 45 ), the controller  58  determines whether or not a certain time has elapsed after this tentative reservation registration in a step S 54 . If it is determined in the step S 54  that the certain time has not elapsed, the processing returns to the step S 47 , so that the identifier of this AV content is compared with the identifier of AV content included in newly received NRT-IT again. 
         [0181]    On the other hand, if it is determined in the step S 54  that the certain time has elapsed, the tentative reservation registration is regarded as invalid and cancelled and the processing proceeds to a step S 55 . In the step S 55 , the controller  58  controls the application engine  63  and makes the display  13 A display a message indicating that download is impossible. 
         [0182]    Furthermore, also when it is determined in the step S 49  that this AV content is not downloadable and viewable, such as when the storage  14  is deficient in the necessary capacity to record the AV content, the message indicating that download is impossible is displayed similarly. When the capacity deficiency of the storage  14  is resolved, definitive reservation registration may be allowed. 
         [0183]    When the processing of the step S 55  is ended, the content reception processing of  FIG. 10  and  FIG. 11  is ended. 
         [0184]    That is, if the certain time elapses after tentative reservation registration or if this AV content is not downloadable and viewable, the message is displayed and download of the AV content is not performed. 
         [0185]    In a step S 56 , the trigger detector  57  determines whether or not trigger information is detected from the multiplexed stream separated by the demultiplexer  52 . 
         [0186]    If it is determined in the step S 56  that trigger information is detected, the processing proceeds to a step S 57 . In the step S 57 , the controller  58  analyzes the command indicated by the detected trigger information. 
         [0187]    In a step S 58 , the controller  58  determines whether or not the analyzed command is Terminate. If it is determined in the step S 58  that the command is Terminate, the processing proceeds to a step S 59 . 
         [0188]    In the step S 59 , if TDO content that is the data broadcasting application specified by App_id of this trigger information is running, the application engine  63  stops it. Then the processing proceeds to a step S 60 . 
         [0189]    If trigger information is not detected (“No” of the step S 56 ) or if the analyzed command is not Terminate (“No” of the step S 58 ), the processing of trigger information is skipped and the processing proceeds to the step S 60 . Furthermore, the processing of the end of TDO content based on trigger information may be executed not only after the end of definitive reservation registration but after the end of tentative reservation registration or the like for example. 
         [0190]    In the step S 60 , the download reservation unit  65  determines whether or not the present time has become the broadcast start time of AV content for which definitive reservation is registered, and waits until the present time becomes the broadcast start time. This broadcast start time is specified by Distribution start/end described in NRT-IT. If it is determined in the step S 60  that the present time has become the broadcast start time, the processing proceeds to a step S 61 . 
         [0191]    In the step S 61 , the download reservation unit  65  controls the tuner  51  to download AV content of a predetermined channel. The multiplexed stream received by the tuner  51  and demodulated is separated by the demultiplexer  52  and recorded in the storage  14 . In the storage  14 , information of NRT-IT and so forth is also recorded together with the AV content. Furthermore, if two or more pieces of AV content are selected, the processing of the steps S 61  and S 61  is repeated and all pieces of AV content are downloaded. Moreover, if AV content is acquired from a delivery server connected to the Internet  17 , the download reservation unit  65  controls the communication I/F  61  to download the AV content of a predetermined channel and the downloaded AV content is recorded in the storage  14 . 
         [0192]    After the end of the download of AV content, in a step S 62 , the controller  58  controls the application engine  63  to display a list of the downloaded AV content. 
         [0193]    In a step S 63 , the controller  58  accepts selection of AV content to be reproduced from the displayed list of AV content based on operation of the operation part  60  by the user. 
         [0194]    If AV content is selected by the user, the video decoder  53  and the audio decoder  55  read out the encoded video stream and the encoded audio stream, respectively, corresponding to the selected AV content from the storage  14 . Subsequently, the video decoder  53  decodes the encoded video stream and outputs the video signal obtained as the result to the display  13 A. Furthermore, the audio decoder  55  decodes the encoded audio stream and outputs the audio signal obtained as the result to the speaker (not shown). 
         [0195]    Thereby, the AV content that is downloaded from the broadcasting device  11  and recorded in the storage  14  is reproduced and viewed by the user (step S 64 ). 
         [0196]    In the above-described manner, in the receiving device  13 , trigger information transmitted together with AV content is detected and TDO content as a data broadcasting application is acquired based on the detected trigger information. In addition, desired AV content is selected based on the TDO content. Subsequently, the desired AV content selected based on the TDO content is registered as tentative reservation, and the tentatively reserved AV content is registered as definitive reservation if the identifier of downloadable AV content included in periodically transmitted NRT-IT is identical to the identifier of the tentatively reserved AV content. 
         [0197]    Due to this, even if the NRT-IT retained by the receiving device  13  is not the latest, tentative reservation of the desired AV content is registered and the tentative reservation registration is changed to definitive reservation registration after NRT-IT is newly received. Thus, there is no need to await download reservation until NRT-IT is newly received. Therefore, loss of the opportunity for download reservation of AV content is eliminated and thus download reservation of AV content in the NRT service can be surely carried out. As a result, the opportunity for the download reservation can be widened. 
         [0198]    The above-described broadcasting system  1  of  FIG. 1  realizes data broadcasting content that can be in conjunction with AV content in the state in which the band for broadcasting data broadcasting content is not set in the broadcasting band of digital television broadcasting like in e.g. the present United States. Furthermore, in the above description, the example in which AV content is broadcast by the broadcasting device  11  based on a digital television broadcast signal is mainly explained. However, as described above, a dedicated delivery server may be provided and AV content may be delivered via the Internet  17 . 
         [0199]    In addition, in the above description, TDO content is explained as a data broadcasting application and the example in which AV content permitted to be tentatively reserved is displayed on the display  13 A and selected based on the TDO content is explained. However, AV content may be selected without displaying on the display  13 A. For example, through execution of TDO content by the controller  58 , AV content may be selected based on conditions set in advance and so forth. 
         [0200]    Moreover, the TDO content may be not only acquired and activated based on trigger information but also activated from another piece of TDO content. Furthermore, it is explained that the TDO content is described by HTML. However, the TDO content is configured from JavaScript, JPEG file, PNG file, etc. besides HTML. In addition, it is also possible to employ another description language such as BML (Broadcast Markup Language) as the description language of the TDO content. 
         [0201]    Moreover, in the above description, the Pull-type NRT broadcasting is explained. However, the above-described configuration can be similarly applied also to the Push-type NRT broadcasting. 
         [0000]    [Description of Computer to which the Present Technique is Applied] 
         [0202]    The above-described series of processing can be executed by hardware and can also be executed by software. In the case of executing the series of processing by software, a program configuring the software is installed into a general-purpose computer or the like. 
         [0203]    So,  FIG. 14  shows a configuration example of one embodiment of the computer into which the program to execute the above-described series of processing is installed. 
         [0204]    The program can be recorded in advance in a storing unit  108  such as a hard disc or a ROM (Read Only Memory)  102  incorporated in a computer  100 . 
         [0205]    Alternatively, the program can be stored (recorded) temporarily or permanently in removable media  111  such as flexible disc, CD-ROM (Compact Disc Read Only Memory), MO (Magneto Optical) disc, DVD (Digital Versatile Disc), magnetic disc, and semiconductor memory. Such removable media  111  can be provided as so-called package software. 
         [0206]    Besides the installation from the above-described removable media  111  into the computer  100 , the program can be wirelessly transferred from a download site to the computer  100  via an artificial satellite for digital satellite broadcasting or can be transferred to the computer  100  by wiring via a network such as a LAN (Local Area Network) or the Internet. In the computer  100 , the thus transferred program can be received by a communication unit  109  and installed into the storing unit  108 . 
         [0207]    The computer  100  includes a CPU (Central Processing Unit)  101 . To the CPU  101 , an input/output interface  105  is connected via a bus  104 . When an order is input via the input/output interface  105  through operation of an input unit  106  composed of keyboard, mouse, microphone, etc. by the user and so forth, the CPU  101  runs a program stored in the ROM  102  in accordance with it. Alternatively, the CPU  101  loads, in a RAM (Random Access Memory)  103 , and runs a program stored in the storing unit  108 , a program that is transferred from a satellite or a network to be received by the communication unit  109  and installed into the storing unit  108 , or a program that is read out from the removable media  111  mounted in a drive  110  and installed into the storing unit  108 . Thereby, the CPU  101  executes processing in accordance with the above-described flowchart or processing executed based on the configuration of the above-described block diagram. Subsequently, according to need, for example the CPU  101  makes the processing result be output from an output unit  107  composed of LCD (Liquid Crystal Display), speaker, etc. or transmitted from the communication unit  109  and recorded in the storing unit  108 , and so forth, via the input/output interface  105 . 
         [0208]    Here, in the present specification, the processing steps that describe the program for making a computer execute various kinds of processing do not necessarily need to be processed in a time-series manner along the order described as the flowchart and encompass also processing executed in parallel or individually (e.g. parallel processing or processing by an object). 
         [0209]    Furthermore, the program may be one processed by one computer or may be one subjected to distributed processing by plural computers. Moreover, the program may be one transferred to a distant computer and executed. 
         [0210]    In the present specification, the system refers to the whole of a device configured with plural devices. 
         [0211]    Moreover, embodiments of the present technique are not limited to the above-described embodiment and various changes can be made in such a range as not to depart from the gist of the present technique. 
         [0212]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.