Patent Publication Number: US-2015067510-A1

Title: Display system, recording medium, and selection control method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to the field of selection control. More particularly, the present invention relates to a display system, a recording medium, and a selection control method which are adapted to control selection of content data to be played back on a display device. 
     2. Description of the Related Art 
     Conventionally, display systems in which content data selected on an information terminal is supplied to a display device and the content data is played back on the display device are known. 
     For example, among the conventional systems, the following technology is known. In this technology, when a playback request of content data selected on the information terminal is made, it is determined whether the selected content data is capable of being played back on the display device. If it is determined that the selected content data is incapable of being played back on the display device, a warning message is output to the information terminal. For example, see Japanese Laid-Open Patent Publication No. 2010-232760. 
     In the case of the above-described technology, the determination as to whether content data is capable of being played back on the display device cannot be made until the content data is selected on the information terminal. Hence, in the conventional technology, even if a user selects desired content data and makes a playback request of the selected content data, there may be a case in which the selected content data is incapable of being played back on the display device. In such a case, the user may be required to perform an operation for selecting other content data. Hence, the user must perform a repetitive operation. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention provides a display system, a recording medium, and a selection control method which are adapted to supply increased operability in selection of content data to be played back on a display device. 
     In an embodiment which solves or reduces one or more of the above-described problems, the present invention provides a display system including a display device and an information terminal adapted to communicate with the display device, the information terminal including a processor and a storage part storing instructions which when executed by the processor cause the processor to perform a process including: determining whether content data stored in the storage part is capable of being played back on the display device based on information associated with playback capability of the content data on the display device; displaying a list screen of identification information items of content data when the content data is determined as being capable of being played back on the display device; and transmitting, to the display device, content data corresponding to identification information items which are selected from the list screen displayed. 
     Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an overall configuration of a display system according to a first embodiment. 
         FIG. 2  is a diagram for explaining a scenario in which the display system according to the first embodiment is utilized. 
         FIG. 3  is a diagram showing a hardware configuration of each of an information terminal and a display device of the display system. 
         FIG. 4  is a diagram showing a functional configuration of each of the information terminal and the display device of the display system. 
         FIG. 5  is a sequence diagram for explaining operation of the display system according to the first embodiment. 
         FIG. 6  is a flowchart for explaining a list screen display process performed by the information terminal. 
         FIG. 7  is a diagram showing an example of a list screen displayed on the information terminal. 
         FIG. 8  is a diagram showing another example of the list screen displayed on the information terminal. 
         FIG. 9  is a flowchart for explaining a list screen display process performed by an information terminal of a display system according to a second embodiment. 
         FIG. 10  is a diagram showing an example of a list screen displayed on the information terminal of the display system. 
         FIG. 11  is a diagram showing another example of the list screen displayed on the information terminal of the display system. 
         FIG. 12  is a diagram showing a functional configuration of each of an information terminal, a display device, and a playback capability information provision server of a display system according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will be given of embodiments with reference to the accompanying drawings. 
     In a display system according to one embodiment, content data that is determined as being capable of being played back on a display device is displayed in a content data list screen on an information terminal, and it is possible to supply increased operability in selection of the content data. 
     First Embodiment 
     A display system according to a first embodiment is explained.  FIG. 1  shows an overall configuration of a display system  100  according to the first embodiment. 
     The display system  100  includes an information terminal  200  and a display device  300 . In the display system  100 , the information terminal  200  and the display device  300  are connected via a data transmission path N such as a network, so that the information terminal  200  and the display device  300  communicate with each other. 
     The information terminal  200  may perform communication according to a communication protocol complying with the communication standard such as 3G (3rd Generation), LTE (Long Term Evolution) or 4G (4th Generation). Moreover, the information terminal  200  may perform communication according to another communication protocol such as ZigBee or Bluetooth®. 
     The information terminal  200  may be implemented by a wireless communication terminal, such as a smart phone or a mobile phone. Moreover, the information terminal  200  may be implemented by a tablet PC (personal computer) or a notebook PC. The information terminal  200  may be adapted to communicate with the display device  300 . 
     A selection control program  210  is installed in the information terminal  200 . The selection control program  210  when executed by a processor of the information terminal  200  causes the processor to transmit to the display device  300  content data selected on the information terminal  200  and playback control information which will be described later. 
     A playback program  310  is installed in the display device  300 . The playback program  310  when executed by a processor of the display device  300  causes the processor to display the content data received from the information terminal  200  based on the playback control information. 
     The display device  300  may be adapted to have a display function to display the content data based on the playback control information received from the information terminal  200 . The display device  300  may be implemented by a projector or a display unit. 
     In the following, operation of the display device  300  to display the content data based on the playback control information is expressed as playback of the content data. 
     Moreover, the content data may be implemented by image data or video data. The image data used as the content data may be image data indicating a single image or may be image data indicating two or more images. The content data may be implemented by any image data that is capable of being displayed or played back on the display device  300 . 
     In the following, content data which is transmitted from the information terminal  200  to the display device  300  and played back on the display device  300  is called “playback content data”. In other words, the playback content data is the content data selected on the information terminal  200  in order to transmit the same to the display device  300 . Moreover, in the following, two or more items of content data stored in a predetermined storage area are called “content data”, and content data included in content data is also called “content data”. 
     Next, a scenario in which the display system  100  according to the first embodiment is utilized is explained with reference to  FIG. 2 .  FIG. 2  is a diagram for explaining a scenario in which the display system  100  is utilized. 
     In the example of  FIG. 2 , it is assumed that the information terminal  200  is a smart phone or a tablet PC, the display device  300  is configured to include a projector  301  and a screen  302 , and the display system  100  is utilized as a digital signage system. 
     If desired content data is selected by a user on the information terminal  200  and a playback setting of the selected content data (playback content data) is input by the user, the information terminal  200  generates the playback control information of the selected content data based on the playback setting. Subsequently, the information terminal  200  transmits the playback content data and the playback control information to the projector  301 . The projector  301  stores the received playback content data in a storage part  32  (which will be described later) and plays back the playback content data based on the playback control information. 
     In this way, in the display system  100 , if the playback content data and the playback control information are transmitted to the display device  300 , the user may continuously reproduce the playback content data based on the desired playback setting. Namely, when the display system  100  is utilized as a digital signage system, the content data is automatically played back based on the user&#39;s desired playback setting, and it is no longer necessary for the user to spend the time and effort for setting up the sequence of playback of the content data or the switching between display indications on an as-needed basis. 
     Moreover, in this embodiment, a list of identification information items of playback-capable content data which are capable of being played back on the display device  300  is displayed in a content data list screen on the information terminal  200 . Specifically, the information terminal  200  receives information associated with the playback capability of the display device  300  from the display device  300  and compares the information associated with the playback capability with attribute information of each of the content data stored in the storage area  220 . The information terminal  200  determines the content data with which the information associated with the playback capability and the attribute information are in agreement as being the playback-capable content data which is capable of being played back on the display device  300 . Subsequently, the information terminal  200  displays the list of identification information items of the playback-capable content data that is capable of being played back as a content data list screen. 
     In this embodiment, all the content data selected on the information terminal  200  is the playback-capable content data on the display device  300 . Therefore, it is no longer necessary for the user to perform an operation of selecting other content data when the selected content data is incapable of being played back, and it is possible to supply increased operability in selection of the content data. The information associated with the playback capability of the display device  300  and the attribute information of the content data will be described later. 
     Next, a hardware configuration of the display system  100  is explained with reference to  FIG. 3 .  FIG. 3  shows a hardware configuration of each of the information terminal  200  and the display device  300  of the display system  100 . 
     As shown in  FIG. 3 , the information terminal  200  includes a CPU (central processing unit)  21 , a storage part  22 , an input part  23 , an external interface part  24 , a network control part  25 , an output part  26 , and a driver  27 . These components of the information terminal  200  are interconnected by a bus B1. 
     The CPU  21  is configured to control overall operations of the information terminal  200 . The storage part  22  is configured to store various programs including the selection control program  210  executed by the CPU  21  and various information items associated with operations and computations of the information terminal  200 . The input part  23  is configured to receive various signals and information items input by a user. The input part  23  may be configured to have a display functions, such as a touch panel function. Moreover, the input part  23  may be implemented by a pointing device or a keyboard. 
     The external interface part  24  may be implemented by a USB (universal serial bus) memory slot or an NFC (near field communication) module. The network interface part  25  is configured to include a modem or a LAN (local area network) card and used to connect the information terminal  200  to the network. The output part  26  is configured to output various information items from the information terminal  200  to the outside. The output part  26  may be implemented by a display unit, or may be implemented by a transmission unit to transmit various data items to an external device. 
     The selection control program  210  is at least a part of the various programs stored to control the information terminal  200 . The selection control program  210  is supplied to the information terminal  200  by distribution of a recording medium  28  or by downloading the selection control program  210  from the network. Examples of the recording medium  28  in which the selection control program  210  is recorded include a CD-ROM, a flexible disk, a magneto-optical disk, a ROM, a flash memory, etc. 
     If the recording medium  28  in which the selection control program  210  is recorded is set to the driver  27 , the selection control program  210  from the recording medium  28  is installed in the storage part  22  through the driver  27 . If the selection control program  210  is downloaded from the network, the selection control program  210  is installed in the storage part  22  through the network control part  25 . 
     The storage part  22  is configured to store necessary files and data items as well as the various programs including the installed selection control program  210 . The selection control program  210  when read from the storage part  22  and executed by the CPU  21  causes the CPU  21  to perform various processes which will be described later. 
     Moreover, as shown in  FIG. 3 , the display device  300  includes a CPU  31 , a storage part  32 , an input part  33 , an external interface part  34 , a network control part  35 , a display part  36 , and a driver  27 . These components of the display device  300  are interconnected by a bus B2. 
     The CPU  31  is configured to control overall operations of the display device  300 . The storage part  32  is configured to store various programs including the playback program  310  executed by the CPU  31 , various information items associated with operations and computations of the display device  300 , and the playback content data to be played back on the display device  300 . The input part  33  is configured to receive various signals and information items input by a user. The input part  33  may be implemented by an operating unit to operate the display device  300 . 
     The external interface part  34  may be implemented by a USB memory slot or an NFC module. The network control part  35  is configured to connect the display device  300  to the network. The display part  36  is configured to display or play back the playback content data on the display device  300  in accordance with a received playback instruction specifying the playback content data. 
     The playback program  310  is at least a part of the various programs stored to control the display device  300 . The playback program  310  is supplied to the display device  300  by distribution of a recording medium  38  or by downloading the playback program  310  from the network. 
     If the recording medium  38  in which the playback program  310  is recorded is set to the driver  37 , the playback program  310  from the recording medium  38  is installed in the storage part  32  through the driver  37 . If the playback program  310  is downloaded from the network, the playback program  310  is installed in the storage part  32  through the network control part  35 . 
     The storage part  32  is configured to store necessary files and data items including the playback content data as well as the installed playback program  310 . The playback program  310  when read from the storage part  32  and executed by the CPU  31  causes the CPU  31  to perform various processes which will be described later. 
     Next, a functional configuration of the display system  100  is explained with reference to  FIG. 4 .  FIG. 4  shows a functional configuration of each of the information terminal  200  and the display device  300  of the display system  100 . 
     As shown in  FIG. 4 , the information terminal  200  includes a predetermined storage area  220  which is provided in the storage part  22 . For example, content data  221  and setting item information  222  are stored in the storage area  220 . The content data  221  may be image data or video data that is capable of being played back on the display device  300 . The content data  221  may include two or more content data items, or may include one content data item. 
     The setting item information  222  may be information that indicates setting items input by the user when generating the playback control information. 
     Moreover, the information terminal  200  is configured so that, through a later-described process, the information terminal  200  temporarily stores, in the storage area  220 , playback-capable content data  223  determined as being capable of being played back on the display device  300 . 
     When a playback capability information reception unit  211  which will be described later receives playback capability information  331  from the display device  300 , the information terminal  200  stores the received playback capability information  331  in the storage area  220 . 
     As shown in  FIG. 4 , the information terminal  200  includes a playback capability information reception unit  211 , a playback capability determination unit  212 , a display control unit  213 , an input reception unit  214 , a playback-control-information generation unit  215 , and a transmission unit  216 . 
     The playback capability information reception unit  211  is configured to send a reception request of the playback capability information  331  to the display device  300 , receive the playback capability information  331  from the display device  300 , and store the playback capability information  331  in the storage area  220 . 
     The playback capability determination unit  212  is configured to determine whether the content data  221  is capable of being played back on the display device  300  based on the playback capability information  331 . Specifically, the playback capability determination unit  212  receives the attribute information of the content data  221  and compares the attribute information with the playback capability information  331 . The playback capability determination unit  212  determines the content data  221  as being capable of being played back on the display device  300  if a file type and a file format of the content data  221  included in the attribute information are included in the playback capability information  331 . 
     The playback capability determination unit  212  is configured to temporarily store the content data  221 , which is determined as being capable of being played back on the display device  300 , in the storage area  220  as the playback-capable content data  223 . The playback-capable content data  223  may include two or more content data items or may include one content data item. 
     The display control unit  213  is configured to display a list screen of identification information items of the playback-capable content data  223  on the display part which is the output unit  26  of the information terminal  200 . Moreover, the display control unit  213  is configured to display a setting screen for inputting values of setting items included in the setting item information  222  by a user. 
     For example, the identification information items of the playback-capable content data  223  may be thumbnail images when the content data is image data or video data, or may be file names of the content data. It is adequate for the identification information items of the content data to be information that identifies the content data. 
     The input reception unit  214  is configured to receive selection of all or a part of the content data  221  in the list screen of the identification information items of the playback-capable content data  223 . In this embodiment, the content data  221  which is selected in the list screen and to which a transmission request is made is transmitted from the information terminal  200  to the display device  300  as playback content data  332 . 
     Moreover, the input reception unit  214  is configured to receive values of the setting items which are input to the setting screen by the user, the setting screen being displayed on the information terminal  200  for inputting the values of the setting items included in the setting item information  222 . 
     The playback-control-information generation unit  215  is configured to generate playback control information  333  based on information included in the selected playback content data  332 . For example, the playback control information  333  contains a setting item indicating a sequence of playback of items of the content data  221  included in the playback content data  332 , a setting item indicating a playback time of each of the items of the content data  221  included in the playback content data  332 , and a setting item indicating how to switch between display indications of each of the items of the content data  221  included in the playback content data  332 . 
     In this embodiment, a value of a predetermined setting item included in the playback control information  333  is set to a value of the predetermined setting item input to the setting screen by the user. The predetermined setting item may include the playback sequence setting item, the playback time setting item, and the switching effect setting item of the content data  221  contained in the playback content data  332 . 
     The playback-control-information generation unit  215  may be configured to cause, when the playback content data  332  is selected in the list screen, the display control unit  213  to display the setting screen of the predetermined setting items described above, and generate the playback control information  333  based on the input values of the predetermined setting items. Moreover, the playback-control-information generation unit  215  may be configured to store the values of the predetermined setting items input by the user in an arbitrary timing, and generate, when the playback content data  332  is selected, the playback control information  333  by using the stored values of the predetermined setting items. The playback control information  333  is associated with the playback content data  332  and transmitted to the display device  300 . 
     The transmission unit  216  is configured to transmit the playback control information and the playback content data  332  to the display device  300 . 
     In this embodiment, the information terminal  200  includes the storage part  22  in which the content data  221  is stored in the storage area  220 . The present disclosure is not limited to this embodiment. For example, the content data  221  may be stored in a removable recording medium which is readable by the processor of the information terminal  200 . Alternatively, the content data  221  may be stored in an external device which is adapted to communicate with the information terminal  200 . 
     Moreover, as shown in  FIG. 4 , the display device  300  includes a playback capability information transmission unit  311 , a storage control unit  312 , a verification unit  313 , and a notification unit  314 . Moreover, the display device  300  includes a display control part  320  which is configured to control the display of the display part  36 . 
     Furthermore, the display device  300  includes a storage area  330  in which the playback capability information  331 , the playback content data  332 , and the playback control information  333  are stored. 
     The playback capability information  331  is information associated with the playback capability of the content data by the display device  300 . For example, the playback capability information  331  indicates a file type and a file format of the content data which is capable of being played back on the display device  300 . Specifically, the playback capability information  331  includes a file type of playback-capable image data or audio data, and a bit rate, a codec, a resolution, etc. of video data, which are capable of being played back on the display device  300 . 
     The playback content data  332  and the playback control information  333  are information received at the display device  300  from the information terminal  200 . 
     The storage area  330  may be provided in the storage part  32  of the display device  300 , or may be provided in a removable recording medium which is readable by the display device  300 . Alternatively, the storage area  330  may be provided in an external device which is adapted to communicate with the display device  300 . 
     The playback capability information transmission unit  311  is configured to read the playback capability information  331  from the storage area  330  in response to a reception request of the playback capability information  331  from the information terminal  200 , and transmit the playback capability information  331  to the information terminal  200 . 
     The storage control unit  312  is configured to store in the storage area  330  the playback content data  332  and the playback control information  333  which are received from the information terminal  200 . Moreover, the storage control unit  312  is configured to set up the values of the setting items included in the playback control information  333  to the display device  300  when a playback instruction of the playback content data  332  is received from the information terminal  200 . 
     The verification unit  313  is configured to determine whether the playback content data  332  is capable of being played back on the display device  300  based on the playback control information  333 . The details of a verification process performed by the verification unit  313  will be described later. The notification unit  314  is configured to send a notification indicating a verification result from the verification unit  313  to the information terminal  200 . 
     Next, operation of the display system  100  according to this embodiment is explained with reference to  FIG. 5 .  FIG. 5  is a sequence diagram for explaining operation of the display system  100 . 
     As shown in  FIG. 5 , if a user inputs a content data list display instruction of the content data  221  and the content data list display instruction is received by the information terminal  200  (step S 501 ), the information terminal  200  starts the selection control program  210  and receives the playback capability information  331 . 
     Specifically, the information terminal  200  transmits a reception request of the playback capability information  331  to the display device  300  (step S 502 ). In response to this reception request, the display device  300  causes the playback capability information transmission unit  311  to transmit the playback capability information  331  to the information terminal  200  (step S 503 ). For example, in this embodiment, the playback capability information  331  may be included in SSID (service set identifier) of the display device  300  and transmitted to the information terminal  200 . Namely, the information terminal  200  receives the playback capability information  331  when a connection between the information terminal  200  and the display device  300  is established. 
     When the playback capability information  331  is received from the display device  300 , the information terminal  200  displays the list screen of the identification information items of the playback-capable content data  223  included in the content data  221  (step S 504 ). The details of the content data list screen display process at step S 504  will be described later. 
     Subsequently, the information terminal  200  causes the input reception unit  214  to receive selection of the content data  221  in the list screen (step S 505 ). The content data  221  selected here is the content data contained in the playback-capable content data  223 . 
     After the content data  221  is selected, the information terminal  200  sends a notification indicating the reception of the selection to the user (step S 506 ). The details of the notification to the user here will be described later. 
     In this embodiment, the processing of steps S 505  and S 506  is repeated until the selection operation of the content data  221  by the user is completed. 
     Subsequently, the information terminal  200  displays the setting screen for inputting the values of the predetermined setting items of the playback control information  333 , and causes the input reception unit  214  to receive the input values of the predetermined setting items (step S 507 ). The input values of the predetermined setting items are associated with the corresponding setting items and stored. 
     Subsequently, if a transmission request of the playback content data  332  input by the user is received (step S 508 ), the information terminal  200  causes the playback-control-information generation unit  215  to generate the playback control information  333  (step S 509 ). Specifically, if a transmission request is received, the playback-control-information generation unit  215  substitutes the stored values of the setting items into a predetermined format and generates the playback control information  333 . 
     Subsequently, the information terminal  200  causes the transmission unit  216  to transmit the playback control information  333  to the display device  300  (step S 510 ). 
     After the playback control information  333  is received from the information terminal  200 , the display device  300  causes the storage control unit  312  to store the playback control information  333  in the storage area  330  (step S 511 ). 
     Subsequently, the information terminal  200  reads the content data  221 , which is selected from the list screen displayed at step S 504 , and causes the transmission unit  216  to transmit the selected content data  221  to the display device  300  as the playback content data  332  (step S 512 ). After the playback content data  332  is received from the information terminal  200 , the display device  300  causes the storage control unit  312  to store the playback content data  332  in the storage area  330  (step S 513 ). 
     In this embodiment, for example, a folder associated with the information terminal  200  may be provided in the storage area  330  of the display device  300 , and the playback content data  332  and the playback control information  333  may be stored in this folder. 
     Subsequently, the display device  300  causes the notification unit  314  to send to the information terminal  200  a notification indicating that storage (uploading) of the playback content data  332  into the storage area  330  is finished (step S 514 ). 
     After the notification is received from the display device  300 , the information terminal  200  transmits a playback instruction of the playback content data  332  to the display device  300  (step S 515 ). After the playback instruction is received from the information terminal  200 , the display device  300  sets up the values of the setting items included in the playback control information  333  to the display device  300  so that the playback content data  332  may be played back according to the playback control information  333 . 
     Moreover, after the playback instruction is received, the display device  300  causes the verification unit  313  to determine whether the playback content data  332  is capable of being played back on the display device  300  based on the playback control information  333  (step S 516 ). 
     Subsequently, the display device  300  causes the notification unit  314  to send a notification indicating a verification result from the verification unit  313  to the information terminal  200  (step S 517 ). Specifically, when it is determined at step S 516  that the playback content data  332  is capable of being played back on the display device  300 , the notification unit  314  may send to the information terminal  200  a notification indicating that the transmission of the content data has been performed successfully. After the notification is received from the notification unit  314 , the information terminal  200  displays a result of the verification (step S 518 ). 
     On the other hand, when it is determined at step S 516  that the playback content data  332  is incapable of being played back on the display device  300 , the notification unit  314  may send to the information terminal  200  a notification indicating that the transmission of the content data has failed. For example, the playback content data  332  is determined as being incapable of being played back on the display device  300  when path information indicating a storing position of the content data  221  is not included in the playback control information  333  or when the playback control information  333  is in a format which is not readable by the display device  300 . 
     In this embodiment, when the transmission of the content data has failed, a message requesting the user to re-transmit the playback content data  332  may be displayed on the information terminal  200 . 
     After step S 518  is performed, the display device  300  plays back the playback content data  332  based on the playback control information  333  (step S 519 ). 
     Next, the content data list screen display process performed at step S 504  in the sequence diagram of  FIG. 5  is explained with reference to  FIG. 6 .  FIG. 6  is a flowchart for explaining the content data list screen display process performed by the information terminal  200 . 
     As shown in  FIG. 6 , after the playback capability information  331  is received from the display device  300  (step S 601 ), the information terminal  200  starts performing the determination as to whether the content data is capable of being played back on the display device  300  with respect to all the items of the content data  221  stored in the storage area  220  (step S 602 ). 
     The playback capability determination unit  212  reads the content data  221  from the storage area  220  (step S 603 ). Subsequently, the playback capability determination unit  212  receives the attribute information of the read content data  221  (step S 604 ). 
     Here, the attribute information of the content data is explained. For example, the attribute information of the content data  221  may include items, such as a file name of the content data  221 , a file type, a file format, a storing position of the content data  221 , a file size, and an update date and time of the content data  221 . Moreover, when the content data  221  is video data, the attribute information thereof may include a bit rate, a codec, a resolution, etc. of the video data. 
     After step S 604  is performed, the playback capability determination unit  212  compares the playback capability information  331  with the attribute information of the read content data  221 , and determines whether the content data  221  is capable of being played back on the display device  300  (step S 605 ). 
     Specifically, the playback capability determination unit  212  determines whether a file type and a file format of the content data  221  indicated by the attribute information received at step S 604  are in agreement with a file type and a file format included in the playback capability information  331 . 
     When the file type and the file format of the content data  221  are in agreement with those included in the playback capability information  331 , the playback capability determination unit  212  determines that the content data  221  read at step S 603  is capable of being played back on the display device  300 . On the other hand, when the file type and the file format of the content data  221  and the playback capability information  331  are not in agreement, the playback capability determination unit  212  determines that the content data  221  is incapable of being played back on the display device  300 . 
     When it is determined at step S 605  that the content data  221  is capable of being played back (YES in step S 605 ), the display control unit  213  temporarily stores the content data  221  in the storage area  220  as the playback-capable content data  223 , and displays the list screen of the identification information items of the content data  221  (step S 606 ). In this case, the display control unit  213  displays the list screen of the identification information items of the content data  221  in a selectable condition in which the identification information items in the list screen are selectable by the user. 
     When the list screen of the content data  221  is displayed in the selectable condition, a user&#39;s touch on one of the identification information items of the content data  221  in the list screen displayed in the viewing area is detected as a selection instruction of a corresponding item of the content data  221 . However, the present disclosure is not limited to detection of a user&#39;s contact. For example, another operation which is performed by the user with a pointing device or the like on the viewing area in which the identification information items of the content data  221  are displayed may be detected as a selection instruction of a corresponding item of the content data  221 . 
     On the other hand, when it is determined at step S 605  that the content data  221  is incapable of being played back (NO in step S 605 ), the playback capability determination unit  212  sets the identification information items of the content data  221  read at step S 603  in a non-display condition, and the determination of the playback capability of the content data  221  in the display process shown in  FIG. 6  is finished (step S 607 ). 
     The processing of steps S 602  to S 607  performed by the playback capability determination unit  212  and the display control unit  213  in the information terminal  200  is repeated for all the content data  221  stored in the storage area  220 . 
     As a result, the list screen of the identification information items of the playback-capable content data  223  which is capable of being played back on the display device  300  is displayed on the information terminal  200 . 
       FIG. 7  shows a list screen  71  displayed on the information terminal  200 . 
     As shown in  FIG. 7 , in the list screen  71 , only the identification information items of the playback-capable content data  223 , which are determined as being capable of being played back on the display device  300  in the display process of  FIG. 6 , are displayed. In the example of  FIG. 7 , the identification information items of the content data  223  are implemented by thumbnail images of the playback-capable content data  223 . 
     Alternatively, when the identification information items of the playback-capable content data  223  are implemented by file names of the playback-capable content data, a list of file names may be displayed in the list screen  71 . 
       FIG. 8  shows a list screen  71 A displayed on the information terminal  200 . 
     In the list screen  71 A shown in  FIG. 8 , a list of the identification information items of the playback-capable content data  223  and a message  72  indicating the presence of playback-incapable content data  221 , which are determined as being incapable of being played back on the display device  300 , are displayed. In this case, when there are some items of the content data  221  determined as being incapable of being played back, the message  72  may indicate the number of playback-incapable content data items. 
     Hence, the user may easily recognize the presence of playback-incapable content data  221  by displaying the message  72  together with the list screen  71 A. For example, if an identification information item of the content data  221  which the user intends to select is not displayed in the list screen  71 A, the user may easily recognize that the corresponding item of the content data  221  which the user intends to select is incapable of being played back. 
     In this embodiment, the display process in which the identification information items of the content data  221  are displayed in the list screen is performed on the respective items of the content data  221  read from the storage area  220 , based on the result of the determination of the playback capability on the display device  300 . However, the present disclosure is not limited to this embodiment. 
     For example, the determination of the playback capability of all of the items of the content data  221  stored in the storage area  220  may be performed in advance by the playback capability determination unit  212 . In this case, after the playback capability determination unit  212  processes all of the items of the content data  221 , the display control unit  213  may extract the items of the content data  221  determined as being capable of being played back, and display the list screen including the corresponding thumbnail images. 
     In this embodiment, when a connection between the information terminal  200  and the display device  300  is established, the information terminal  200  receives the playback capability information  331  from the display device  300 . However, the present disclosure is not limited to this embodiment. For example, the playback capability information  331  may be stored beforehand in the storage area  220  of the information terminal  200 . In this case, upon starting of the selection control program  210 , the playback capability information reception unit  211  may read the playback capability information  331  from the storage area  220 . 
     Moreover, the display system  100  may be configured to include a first display device and a second display device having different playback capabilities. In this case, the information terminal  200  may be configured to include a playback capability information table in which identification information items to identify the first and second display devices respectively and playback capability information items of the first and second display devices are associated with each other. 
     Furthermore, the information terminal  200  may be configured to display a selection screen for prompting the user to select one of the display devices included in the display system  100 , and receive the playback capability information  331  of the display device selected by making reference to the playback capability information table. In this case, the list screen of the identification information items of the playback-capable content data  223  corresponding to the selected display device is displayed on the information terminal  200 . Moreover, in this case, the information terminal  200  may be configured to associate the received playback capability information  331  with device identification information to identify the selected display device, and store the playback capability information  331  associated with the device identification information in the playback capability information table. 
     In this embodiment, the list screen  71  is displayed by the display control unit  213  after the playback capability determination process is performed by the playback capability determination unit  212 . However, the present disclosure is not limited to this embodiment. For example, the playback capability determination unit  212  may be configured to perform the playback capability determination process in response to a user&#39;s instruction received when the list screen of the content data  221  is displayed. In this case, the display control unit  213  may be configured to set the identification information items of the content data  221  determined as being incapable of being played back on the display device  300  by the playback capability determination unit  212  in a non-selectable condition or a non-display condition. 
     As described above, the information terminal  200  according to the first embodiment determines, when a content data list display instruction input by a user is received, whether the content data  221  stored in the storage area  220  is capable of being played back on the display device  300 , and displays only the playback-capable content data  221  in the list screen. Namely, all the items of the content data  221  selected in the list screen  71  on the information terminal  200  are capable of being played back on the display device  300 . Hence, it is possible for the display system  100  according to the first embodiment to supply increased operability in selection of the content data  221  while avoiding the case in which the content data  221  selected is incapable of being played back on the display device  300 . 
     Second Embodiment 
     Next, a display system according to a second embodiment is described. The display system according to the second embodiment differs from the display system according to the first embodiment in the list screen display process. In the following, only the points of the second embodiment different from the first embodiment are described, the elements in the second embodiment which are essentially the same as corresponding elements in the first embodiment are designated by the same reference numerals, and a description thereof is omitted. 
       FIG. 9  is a flowchart for explaining a list screen display process performed by an information terminal of the display system according to the second embodiment. 
     Processing of steps S 901  to S 906  in the list screen display process of  FIG. 9  is the same as the processing of steps S 601  to S 606  in the list screen display process of  FIG. 6 , and a description thereof is omitted. 
     In this embodiment, after the list of the identification information items of the content data  221  is displayed in the selectable condition at step S 906 , control progresses to step S 908  which will be described later. 
     As shown in  FIG. 9 , when the playback capability determination unit  212  at step S 905  determines that the content data  221  is incapable of being played back on the display device  300  (NO in step S 905 ), the display control unit  213  is caused to display a list screen of the identification information items of the content data  221  in a non-selectable condition in which the identification information items in the list screen cannot be selected by the user (step S 907 ). 
     When the list screen of the identification information items of the content data  221  in the non-selectable condition, a user&#39;s touch or a user&#39;s operation using a pointing device on one of the identification information items of the content data  221  in the list screen displayed in the viewing area is not detected as a selection instruction of a corresponding item of the content data  221 . 
     Alternatively, the information terminal  200  may be configured so that, when the list screen of the identification information items of the content data  221  in the non-selectable condition, a user&#39;s touch or a user&#39;s operation using a pointing device in the list screen displayed in the viewing area is not detected. 
     Subsequently, the information terminal  200  finishes the determination of the playback capability of the content data  221  in the display process shown in  FIG. 9  (step S 908 ). The processing of steps S 902  to S 908  performed by the playback capability determination unit  212  and the display control unit  213  of the information terminal  200  is repeated for all the content data  221  stored in the storage area  220 . 
       FIG. 10  shows a list screen  101  displayed on the information terminal according to the second embodiment. 
     As shown in  FIG. 10 , in the list screen  101 , the identification information items of the playback-capable content data  223 , which are determined as being capable of being played back on the display device  300  in the display process of  FIG. 9 , are displayed in the selectable condition. Moreover, in the list screen  101 , identification information items  102 ,  103 ,  104  of the content data  221 , which are determined as being incapable of being played back on the display device  300  in the display process of  FIG. 9 , are displayed in the non-selectable condition. 
     The display control unit  213  is configured to display the identification information items of the playback-capable content data  223  and the identification information items of the remaining, playback-incapable content data  221  in mutually different display modes. 
     In the list screen  101 , when the identification information items of the playback-incapable content data  221  are displayed as thumbnail images  102 ,  103 ,  104 , a message indicating that the content data is incapable of being played back may be overlapped on each of the thumbnail images  102 ,  103 ,  104 . Alternatively, in the list screen  101 , only the thumbnail images  102 ,  103 ,  104  may be displayed in a monochrome display mode. 
     In this embodiment, in the list screen  101 , the identification information items of the playback-incapable content data  221  and the identification information items of the playback-capable content data  223  are displayed in mutually different display modes so that the user may easily recognize the playback-incapable content data  221  in the list screen  101 . 
       FIG. 11  shows a list screen  81 A displayed on the information terminal according to the second embodiment. 
     The list of the identification information items of the content data  221  which are determined as being incapable of being played back may be displayed in the non-selectable condition in a viewing area different from the viewing area in which the list of the identification information items of the playback-capable content data  223  is displayed. 
     In this embodiment, the list of the identification information items of the playback-incapable content data  221  is displayed as shown in  FIG. 11  so that the user may easily recognize which content data is incapable of being played back on the display device  300 . 
     Third Embodiment 
     Next, a display system according to a third embodiment is described. The display system according to the third embodiment differs from the display system  100  according to the first embodiment in that the playback capability information  331  is stored in a server over the network. In the following, only the points of the third embodiment different from the first embodiment are described, the elements in the third embodiment which are essentially the same as corresponding elements in the first embodiment are designated by the same reference numerals, and a description thereof is omitted. 
       FIG. 12  shows a functional configuration of each of an information terminal  200 A, a display device  300 A, and a playback capability information provision server  400  of a display system  100 A according to the third embodiment. 
     As shown in  FIG. 12 , the display system  100 A includes the information terminal  200 A, the display device  300 A, and the playback capability information provision server  400 . In this embodiment, a playback capability information table  410 , in which device type information of the display device  300 A and the playback capability information  331  which are associated with each other, is stored in the playback capability information provision server  400 . 
     The playback capability information provision server  400  is provided over the network and configured to supply the information terminal  200 A with the playback capability information  331  in response to a reception request of the playback capability information  331  transmitted by the information terminal  200 A. 
     As shown in  FIG. 12 , a selection control program  210 A is installed in the information terminal  200 A. The information terminal  200 A includes a device type information reception unit  217  in addition to the playback capability information reception unit  211 , the playback capability determination unit  212 , the display control unit  213 , the input reception unit  214 , the playback-control-information generation unit  215 , and the transmission unit  216  as included in the information terminal  200  according to the first embodiment. The selection control program  210 A when executed by a processor of the information terminal  200 A causes the processor to serve as these functional units  211 - 217  of the information terminal  200 A. 
     The device type information reception unit  217  is configured to send a reception request of device type information to the display device  300 A and receive the device type information from the display device  300 A. 
     Moreover, as shown in  FIG. 12 , a playback program  310 A is installed in the display device  300 A. The display device  300 A includes a device type information transmission unit  311 A in addition to the storage control unit  312 , the verification unit  313 , and the notification unit  314  as included in the display device  300  according to the first embodiment. The playback program  310 A when executed by a processor of the display device  300 A causes the processor to serve as these functional units  311 A- 314  of the display device  300 A. 
     Moreover, the display device  300 A includes a storage area  330 A, and device type information  331 A of the display device  300 A to identify the display device  300 A is stored in the storage area  330 A. For example, the device type information  331 A may include a device name and a product identifier which are used to identify the display device  300 A. The device type information  331 A is predetermined for the display device  300 A. 
     The device type information transmission unit  311 A is configured to read the device type information from the storage area  330 A in response to a reception request of device type information transmitted by the information terminal  200 A, and transmit the device type information from the device type information transmission unit  311 A to the information terminal  200 A. 
     In the display system  100 A, if a content data list display instruction associated with the content data  221  input by a user is received at the information terminal  200 A, the information terminal  200 A causes the device type information reception unit  217  to receive the device type information of the display device  300 A. 
     Subsequently, the information terminal  200 A transmits a reception request of the playback capability information  331  to the playback capability information provision server  400  together with the device type information received by the playback capability information reception unit  211 A. 
     In response to the reception request from the information terminal  200 A, the playback capability information provision server  400  acquires playback capability information  331  corresponding to the device type information obtained from the information terminal  200 A by making reference to the playback capability information table  410 , and transmits the acquired playback capability information  331  to the information terminal  200 A. 
     After the playback capability information  331  is received from the playback capability information provision server  400 , the information terminal  200 A causes the playback capability determination unit  212  to perform the playback capability determination in a manner similar to the processing of steps S 602 -S 605  in  FIG. 6  or steps S 902 -S 906  in  FIG. 9 , and causes the display control unit  213  to perform the list screen display process in a manner similar to the processing of step S 606  in  FIG. 6  or steps S 906 -S 907  in  FIG. 9 . 
     As described in the foregoing, it is possible for the display system according to the present invention to supply increased operability in selection of content data to be played back on a display device. 
     The display system according to the present invention is not limited to the above-described embodiments, and variations and modifications may be made without departing from the scope of the present invention. 
     The present application is based upon and claims the benefit of priority of Japanese Patent Application No. 2013-181154, filed on Sep. 2, 2013, the contents of which are incorporated herein by reference in their entirety.