Patent Publication Number: US-8989551-B2

Title: Captioned video playback apparatus and recording medium

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a Divisional Application of U.S. patent application Ser. No. 12/154,026 filed May 19, 2008, which claims priority from prior Japanese Patent Applications No. 2007-133865 filed May 21, 2007, No. 2007-159510 filed Jun. 15, 2007 and No. 2007-203612 filed Aug. 3, 2007, the disclosure contents of which are hereby incorporated herein by reference in their entity. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a captioned video playback apparatus which processes caption lines and video images. 
     2. Description of the Related Art 
     Unexamined Japanese Patent Application KOKAI Publication No. 2003-18491 discloses a caption display device. The caption display device stores a video image and a plurality of caption lines in the video image, and displays any caption line, when selected by a user, and a video image corresponding to the selected caption line. 
     The caption display device displays a video image and a plurality of caption lines on the same screen. When the display area for a video image is limited, therefore, the display area for a caption line is limited too. Depending on the number of characters in a caption line, therefore, the visibility and operability of the screen, when a user views a stream or selects a caption, become degraded. This problem becomes noticeable in case of portable terminals which are demanded of downsizing and have a limited screen size for their portability feature. 
     The caption display device also displays a video image and a caption line corresponding to the displayed video image as well as previous caption lines to the displayed caption line (history of caption lines). This limits information which is acquired from caption lines and a video image. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to improve the convenience of a user when viewing a captioned video. 
     It is another object of the invention to provide an apparatus with a higher visibility of a display image and a higher operability. 
     It is a further object of the invention to provide an apparatus capable of adequately playing back a video image corresponding to a caption line. 
     To achieve the object, according to a first aspect of the invention, there is provided a captioned video playback apparatus comprising: 
     a storage unit that stores a caption signal defining a plurality of caption lines and a video signal defining a plurality of video images in association with a playback timing; 
     a caption select unit that selects one of the plurality of caption lines defined by the caption signal stored in the storage unit; 
     a caption playback unit that plays back the caption line selected by the caption select unit; 
     a video playback unit that plays back the video signal stored in the storage unit; and 
     a mode changeover unit that changes between a caption view mode for playing back a caption line selected by the caption select unit and a video image corresponding to the caption line using the caption playback unit and the video playback unit, and a normal view mode for playing back a video image using the video playback unit. 
     To achieve the object, according to a second aspect of the invention, there is provided a captioned video playback apparatus comprising: 
     a captioned video storage unit that stores a caption signal defining a plurality of caption lines and a video signal defining a plurality of video images in association with a playback timing; 
     a caption playback unit that plays back at least two of the plurality of caption lines defined by the caption signal stored in the captioned video storage unit; 
     a video extraction unit that extracts a video image given with a playback timing corresponding to a playback timing given to each caption line played back by the caption playback unit from the video image defined by the video signal stored in the captioned video storage unit; and 
     a video playback unit that plays back and displays the video image extracted by the video extraction unit. 
     To achieve the object, according to a third aspect of the invention, there is provided a captioned video playback apparatus comprising: 
     a storage unit that stores a caption signal defining a plurality of caption lines and a video signal defining a plurality of video images in association with each other in terms of a playback order; 
     a caption playback unit that plays back at least two of the plurality of caption lines defined by the caption signal; 
     a timer unit that measures a time and detects passing of a predetermined time from the beginning of the playback of the caption line which is being played back by the caption playback unit; 
     a caption changeover unit that controls the caption playback unit to play back a caption line having a next playback order to the caption line currently played back in place of the currently played caption line when the timer unit has detected passing of the predetermined time; 
     a video playback unit that plays back a video image having a playback order corresponding to a caption line currently played back by the caption playback unit from individual video images defined by the video signal; and 
     a list display unit that generates and displays a list of the caption line currently played back by the caption playback unit, a caption line whose playback order precedes that of the currently played caption line by a predetermined order and a caption line whose playback order follows that of the currently played caption line by a predetermined order. 
     The captioned video playback apparatus according to the first aspect of the present invention can adequately change over the state where both (a list of) caption lines and a video image are played back and the state where a video image is played back, thus improving the visibility and operability. 
     The captioned video playback apparatus according to the second aspect of the present invention can play back a plurality of video images and corresponding caption lines in parallel. 
     The captioned video playback apparatus according to the third aspect of the present invention automatically changes a caption line and a video image every time a predetermined time elapses. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These objects and other objects and advantages of the present invention will become more apparent upon reading of the following detailed description and the accompanying drawings in which: 
         FIG. 1  is an external view showing a cell phone according to an embodiment of the invention; 
         FIG. 2  is a block diagram showing the configuration of the cell phone as shown in  FIG. 1 ; 
         FIG. 3A  is a diagram showing an example of data to be stored in a storage unit; 
         FIG. 3B  is a diagram exemplifying the structure of a TSP (Transport Stream Packet); 
         FIG. 3C  is a diagram exemplifying the structure of content data; 
         FIG. 3D  is a diagram exemplifying the structure of a caption PES (Packetized Elementary Stream); 
         FIG. 4  is a diagram showing an example of a data structure of caption management data; 
         FIG. 5  is a diagram showing an example of a data structure of seek-point management information; 
         FIG. 6  is a flowchart illustrating a process of extracting information from content-recorded data and generating caption management data; 
         FIG. 7A  is a diagram showing a first example of a screen to be displayed in a caption-with-list view mode; 
         FIG. 7B  is a diagram showing an example of a screen to be displayed in a normal view mode; 
         FIG. 7C  is a diagram showing a second example of the screen to be displayed in the caption-with-list view mode; 
         FIG. 8  is a flowchart illustrating a process of playing back a captioned video image changing over between the “caption-with-list view mode” and “normal view mode”; 
         FIG. 9  is a flowchart of a video extraction process; 
         FIG. 10  is a diagram showing an example of playback timings for video frames and caption data; 
         FIG. 11  is a diagram showing an example of content-recorded data in which video frames are partly dropped off; 
         FIG. 12  is a flowchart illustrating a video extraction process according to an application example 2 of the first embodiment; 
         FIG. 13  is a diagram for explaining an operation of extracting information from a TV signal to generate caption management data; 
         FIG. 14  is a diagram showing a layout example of the entire display area of a display panel when separated into a caption area, a video area, a soft-key area, and a pict area; 
         FIG. 15  is a diagram showing an example of a screen in a 3-strip display mode; 
         FIG. 16  is a flowchart illustrating a process of extracting a video image corresponding to a playback timing of a caption line; 
         FIG. 17A  is a diagram showing a screen before the screen is scrolled down by one strip in the 3-strip display mode; 
         FIG. 17B  is a diagram showing a screen after the screen is scrolled down by one strip in the 3-strip display mode; 
         FIG. 18  is a flowchart showing a process of scrolling a screen by one strip; 
         FIG. 19A  is a diagram showing an example of the screen when page is fed backward in the 3-strip display mode; 
         FIG. 19B  is a diagram showing an example of the screen when page is fed forward in the 3-strip display mode; 
         FIG. 20  is a flowchart showing a page flipping process; 
         FIG. 21  is a diagram showing an example of a screen before a caption line containing a larger number of characters than the displayable character number of the caption area is fully displayed; 
         FIG. 22A  is a diagram showing a first example of a screen after a caption line containing a larger number of characters than the displayable character number of the caption area is fully displayed; 
         FIG. 22B  is a diagram showing a second example of a screen after a caption line containing a larger number of characters than the displayable character number of the caption area is fully displayed; 
         FIG. 23  is a flowchart illustrating a process of enlarging the caption area; 
         FIG. 24A  is a diagram showing an example of a screen when a normal video image is displayed in the “3-strip display mode”; 
         FIG. 24B  is a diagram showing an example of a screen when a lateral video image is displayed in a “4-strip display mode”; 
         FIG. 25  is a flowchart showing a process of setting screen when a lateral video image is displayed in the “4-strip display mode” or “3-strip display mode” according to the format of video images (lateral video image or normal video image); 
         FIG. 26  is a diagram showing an example of the screen structure in a “lateral display mode”; 
         FIG. 27  is a flowchart showing an example of a process of setting the screen in the “lateral display mode”; 
         FIG. 28  is a diagram showing an example of a data structure of contents list data; 
         FIG. 29A  is a diagram showing a first example of a titled screen when video images of a plurality of contents are displayed at the same time; 
         FIG. 29B  is a diagram showing a titled screen when a content to be played back is changed during display of the titled screen in  FIG. 29A ; 
         FIG. 30  is a flowchart showing a process of changing the title in a “titled display mode” as a captioned video image to be played back is changed; 
         FIG. 31  is a diagram showing an example of a screen in a “video zoom-up display mode”; 
         FIG. 32  is a flowchart illustrating an operation in the “video zoom-up display mode”; 
         FIG. 33  is a diagram showing a screen displaying a caption list together with captioned video image in an application example 2-2; 
         FIG. 34  is a flowchart illustrating an automatic scroll process according to a third embodiment; 
         FIG. 35  is a diagram showing an example of caption management data; 
         FIG. 36A  is a flowchart illustrating a process of generating caption management data in an application example 3-1; 
         FIG. 36B  is a flowchart illustrating an automatic scroll process in the application example 3-1; 
         FIG. 37A  is a diagram showing an example of a data structure of display changeover time information; 
         FIG. 37B  is a flowchart illustrating an automatic scroll process in an application example 3-2; 
         FIG. 38A  is a diagram showing an example of a screen before displaying a sub menu; 
         FIG. 38B  is a diagram showing an example of a screen after displaying the sub menu; 
         FIG. 38C  is a diagram showing an example of a screen for setting a caption changeover time according to the third embodiment; 
         FIG. 38D  is a diagram showing a first example of a screen for setting a caption changeover time according to the application example 3-1; 
         FIG. 38E  is a diagram showing a second example of a screen for setting a caption changeover time according to the application example 3-2; 
         FIG. 38F  is a diagram showing an example of a screen for setting a caption changeover time according to a application example 3-3; 
         FIG. 39A  is a diagram showing a first example of the screen according to the application example 3-1; 
         FIG. 39B  is a diagram showing a second example of the screen according to the application example 3-1; 
         FIG. 39C  is a diagram showing a third example of the screen according to the application example 3-1; 
         FIG. 39D  is a diagram showing an fourth example of the screen according to the application example 3-1; 
         FIG. 40  is a flowchart illustrating an automatic scroll process in the application example 3-1; 
         FIG. 41  is a diagram showing a third example of the data structure of caption management data; 
         FIG. 42  is a diagram showing a fourth example of the data structure of caption management data; 
         FIG. 43A  is a diagram showing an example of a screen when playing back a content whose top video image does not correspond to a top caption line; 
         FIG. 43B  is a diagram showing an example of a screen when playing back a content with a top video image made to correspond to a temporary caption line; 
         FIG. 43C  is a diagram showing an example of a screen when playing back a content whose last video image does not correspond to a last caption line; 
         FIG. 43D  is a diagram showing an example of a screen when playing back a content with a last video image made to correspond to a temporary caption line; 
         FIG. 44  is a flowchart illustrating a process of displaying a temporary caption line corresponding to a top video image in the application example 3-2; and 
         FIG. 45  is a flowchart illustrating a process of displaying a caption line preceding the currently displayed caption line by one in the application example 3-2. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     A captioned video playback apparatus according to an embodiment of the present invention will be described below. The embodiment is an example of a captioned video playback apparatus adapted to a cell phone  1  having a content receiving capability. The cell phone  1  can receive contents according to an arbitrary data transform system. The cell phone  1  herein receives one-segment broadcasting. 
     The cell phone  1 , which has a content recording/playback capability, is of a foldable type including a keyboard  2 , a display panel  5 , etc. as shown in  FIG. 1 . 
     The keyboard  2  has a cursor key  3 , a display changeover button  4  and other various buttons. The keyboard  2  when operated by a user inputs various data and instructions. For example, the keyboard  2  is used to input instructions to play back and terminate a captioned video image, and enable or disable display of a list of captions or subtitles (hereinafter “caption list”). 
     The display panel  5  is a dot matrix type LCD (Liquid Crystal Display) panel or the like, and displays data (e.g., captioned video image, caption list, etc.). 
     The cell phone  1  has a talk microphone  6 , a talk speaker  7 , a speaker  8  and so forth arranged thereon. The talk microphone  6  inputs speech sounds. The talk speaker  7  outputs received sounds. The speaker  8  outputs sounds or the like at the time of playing back contents. 
     The circuit configuration of the cell phone  1  will be described. The cell phone  1 , as shown in  FIG. 2 , has a control unit  11 , a storage unit  12 , an operational section  13 , a display unit  14 , a tuner  15 , a decoder  16 , a voice output unit  17 , a voice input unit  18 , a communication unit  19  and a bus  20 . 
     The control unit  11  includes a microprocessor unit or the like, and controls the general operation of the cell phone  1 . For example, the control unit  11  controls the start and termination of playback of recorded contents (video images). The control unit  11  displays data (caption line, video image, caption list, etc.) on the display panel  5  via the display unit  14 . 
     The storage unit  12  stores various kinds of data. For example, the storage unit  12  stores an operation control program for the control unit  11 . The storage unit  12  includes a memory incorporated in the cell phone  1  and/or a dismountable external memory. The operational section  13  having the keyboard  2  supplies an operation signal to the control unit  11  in response to a user&#39;s operation. 
     The display unit  14  includes the display panel  5 , a driver circuit, etc., and displays an image on the display panel  5  under the control of the control unit  11 . The tuner  15  demodulates a one-segment broadcast content received through an antenna, and outputs a demodulated signal (baseband signal) to the decoder  16 . The decoder  16  decodes the content output from the tuner  15 , and outputs the decoded content. 
     The voice output unit  17  includes the talk speaker  7 , the speaker  8 , a DAC (Digital Analog Converter), and so forth. For example, the voice output unit  17  performs DA conversion of an audio signal of the content played back by the control unit  11 , and generates the resultant signal through the speaker  8 . The voice input unit  18  collects audio signals and supplies them to the communication unit  19  at the time of talking or so. The communication unit  19  transmits and receives a speech, various kinds of data and the like via a base station. The bus  20  transfers data among the individual units. 
     A description will now be given of information necessary for a caption list display operation which characterizes the embodiment. The storage unit  12  shown in  FIG. 2  stores content-recorded data  121 , caption management data  122  and seek-point management information  123  as shown in  FIG. 3A . 
     A one-segment broadcast content (TV signal) is comprised of a TSP (Transport Stream Packet) as shown in  FIG. 3B . As illustrated, the TSP is constituted by a stream of a plurality of packets. A plurality of packets include a video packet V (containing VI and VP to be described later) storing video data in a payload, an audio packet Ap storing audio data in a payload, and a caption packet Cp storing caption data in a payload. 
     The control unit  11  classifies individual packets constituting the received TSP according to the types of data stored therein. The control unit  11  rearranges the order of the classified packets based on packet numbers given to the individual packets to generate a video PES (Packetized Elementary Stream)  131 , an audio PES  132 , and a caption PES  133  shown in  FIG. 3C . The control unit  11  stores those PESs into the storage unit  12  as content-recorded data  121 . 
     The video PES  131  is compressed coded data of a packetized video frame, and includes data defining each video frame (video image). Each video frame includes data indicating its playback timing. 
     A TSP in one-segment broadcasting is data conforming to the predictive coding system. Therefore, the video PES  131  includes an IDR (Instantaneous Decoder Refresh) frame (corresponding to an independent video packet VI) that does not refer to other video frames, and a P frame (corresponding to reference video packet VP) that refers to an IDR frame which is played back earlier than its own playback timing. 
     In one-segment broadcasting, the frame rate of a video frame is 15 frames/sec. 
     The audio PES  132  is packetized compressed coded audio data. 
     The caption PES  133  is packetized compressed coded data of a caption line. The caption PES  133  includes information needed to generate the caption management data  122 . For example, as shown in  FIG. 3D , the caption PES  133  has information indicating caption lines Mn (n: 1 to N, N: the number of caption PESs in the content-recorded data  121 ), caption playback timings TMn (n: 1 to N) and control codes CSn (n: 1 to N). 
     The “caption line Mn” is data which indicates the content of a caption line of a captioned video image and is to be stored as the Mn of the caption management data  122 . The “caption playback timing TMn” indicates the timing of playing back a caption line Mn and is presented by a PTS (Presentation Time Stamp) unit. In one-segment broadcasting, each caption line is generated once every 15 seconds. 
     As shown in  FIG. 4 , the caption management data  122  associates a “caption playback timing (display time) TMn” with a “caption line Mn”. The “caption playback timing TMn” indicates the time when the Mn is displayed. In the embodiment, the caption playback timing TMn is an offset time with the playback start time for the content-recorded data  121  being a reference. The “caption line Mn” indicates the content of a caption line of a captioned video image. The caption playback timing TMn may be a frame number or the like. 
     The seek-point management information  123 , as shown in  FIG. 5 , associates a video playback timing TRn (n: 1 to N) of each frame with a video position PRn (n: 1 to N). 
     The “video playback timing TRn” indicates the time when each video frame is displayed, and is displayed by the PTS unit. The “video position PRn” is an index indicating the position of a video frame in the content-recorded data  121 . In the embodiment, the “video position PRn” is represented by the number (packet number) of a TSP including the head of an IDR frame. 
     A description will now be given of the operation of the cell phone  1  according to the first embodiment having the foregoing configuration. The communication operation of the cell phone  1  itself is identical to that of an ordinary cell phone. The operation of the cell phone  1  to play back a captioned video image which characterizes the embodiment will be described below. 
     The cell phone  1  has a “normal view mode” for playing back a captioned video image without displaying a caption list, and a “caption-with-list view mode” for playing back a captioned video image while displaying a caption list and accepting selection of a caption line. In the caption-with-list view mode, a user (viewer) can select an arbitrary caption line from the caption list displayed. When a caption is selected, the selected caption line is displayed and a video image corresponding to the caption line is displayed. 
     Operating the display changeover button  4  or a soft-key, the user can switch the screen display state between the “caption-with-list view mode” and the “normal view mode”. 
     When the user selects the “caption-with-list view mode”, the control unit  11  displays a captioned video image and a list of captions. The caption list includes the caption line currently played back and a predetermined number of caption lines positioned before and after the currently played caption line. Caption lines to be listed are a currently played caption line and caption lines whose playback timings lie within a predetermined time range with the playback timing of the currently played caption line being a reference. 
     The screen to be displayed on the display panel  5  in the “caption-with-list view mode” is a screen D 1  shown in  FIG. 7A . In the embodiment, there are five caption lines shown in the caption list. 
     When displaying a caption list, the control unit  11  reads caption lines Mn from the caption management data  122 . In this respect, the control unit  11  extracts information from caption PESs included in the content-recorded data  121 , and generates the caption management data  122  beforehand. 
     The following will describe the operation of the control unit  11  to generate the caption management data  122 . 
     After recording a content (TV signal), the control unit  11  starts generating the caption management data  122 . As shown in  FIG. 6 , the control unit  11  determines whether a caption PES is present in the content-recorded data  121 , and terminates the process when there is no caption PES (step S 11 ; No). 
     When a caption PES is present (step S 11 ; Yes), the control unit  11  extracts the caption PES (step S 12 ). The control unit  11  determines whether a caption line Mn could be extracted from the caption PES (step S 13 ). When the extraction is done (step S 13 ; Yes), the control unit  11  analyzes the caption PES and acquires a caption playback timing TMn. 
     Subsequently, the control unit  11  acquires an elapse time (PTS unit) from the beginning of the playback of a video image to playback of the caption line Mn by subtracting the playback timing of the top frame in the content-recorded data  121  from the caption playback timing TMn (step S 14 ). 
     The control unit  11  converts the acquired elapse time (PTS unit) to the units of hour, minute and second (step S 15 ). The control unit  11  stores the elapse time (HMS unit) in the caption management data  122  as the caption playback timing TMn (step S 16 ). 
     Then, the control unit  11  extracts a caption line Mn from the caption PES  133 , and stores the caption line Mn in the caption management data  122  (step S 17 ). The control unit  11  repeats the foregoing process until data reaches the end of the content-recorded data  121  (step S 18 ; Yes). This is the end of generation of the caption management data  122 . 
     When the user instructs to change the mode from the “caption-with-list view mode” to the “normal view mode” by operating the display changeover button  4  or a predetermined soft key (e.g., screen “soft  1 ” key), the control unit  11  controls the display unit  14  in such a way that the display of a caption list is terminated and only a captioned video image is displayed. More specifically, the control unit  11  displays a screen D 2  displaying a captioned video image exemplified in  FIG. 7B  on the display panel  5  in place of the screen D 1  shown in  FIG. 7A . To make good use of free space, the control unit  11  displays an image on a relatively large screen with the display size of a video image and a caption line being multiplied by a predetermined value k vertically and horizontally. Alternatively, arbitrary information (e.g., received news, message or the like) other than a caption list is displayed. 
     In this case, when the user instructs to change the mode from the “normal view mode” to the “caption-with-list view mode” by operating the display changeover button  4  or a predetermined soft key, the control unit  11  displays a caption list while keeping the operation of playing back a captioned video image. For example, the control unit  11  displays a screen D 3  shown in  FIG. 7C  in place of the screen D 2  displaying a captioned video image exemplified in  FIG. 7B . 
     A description will now be given of the process of the control unit  11  to change over the display mode for a captioned video image between the “normal view mode” and the “caption-with-list view mode” according to a user&#39;s operation. 
     As shown in  FIG. 8 , when detecting depression of the display changeover button  4  or a predetermined soft key (e.g., “soft  1 ” in  FIG. 7A ) by the user, the control unit  11  determines which one of the “caption-with-list view mode” and the “normal view mode” is instructed as a view mode to be changed to (step S 21 ). When the view mode at the time of detection is the “normal view mode”, the control unit  11  determines that the mode change to the “caption-with-list view mode” has been instructed. 
     When it is the mode change to the “caption-with-list view mode” (step S 21 ; caption-with-list view mode), the control unit  11  acquires the video playback timing for a video image which has been played back when the mode change has been instructed (hereinafter “changeover display time TS”) (step S 22 ). The changeover display time TS can be acquired from, for example, the video playback timing TRn for the currently played caption line, a reference time (STC) for managing the video playback timing or the like. 
     Subsequently, the control unit  11  compares the changeover display time TS with each caption playback timing TMn in the caption management data  122  to specify a caption line Mn which has the latest caption playback timing TMn later than the changeover display time TS (step S 23 ). This is the caption line whose playback will start after the changeover. 
     Then, the control unit  11  specifies the specified caption line Mn and the caption lines to be played back before or after the specified caption line Mn by a predetermined timing (within a range thereof), and displays a list of the caption lines (caption list) on the display panel  5  (step S 24 ). At this time, the control unit  11  displays the currently played caption line Mn in the center of a list area LA for displaying a caption list. 
     Subsequently, the control unit  11  extracts a video image having a video playback timing corresponding to the caption line Mn from the content-recorded data  121 , and displays the video image in a video area RA (step S 25 ). 
     The details of the process at step S 25  are shown in  FIG. 9 . As illustrated therein, the control unit  11  extracts information of a video frame from the video PES (step S 251 ). The control unit  11  determines whether the extracted video frame is an IDR frame based on the extracted information (step S 252 ). When the extracted video frame is not an IDR frame (step S 252 ; No), the process returns to step S 251 . 
     When the extracted video frame is an IDR frame (step S 252 ; Yes), on the other hand, the control unit  11  acquires an elapse time from the beginning of the playback of a top video image (frame) in the content-recorded data  121  to the playback of the IDR frame (step S 253 ). For example, the control unit  11  acquires an elapse time by subtracting the playback timing of the top video image from the video playback timing (PTS unit) for the extracted IDR frame. 
     Next, the control unit  11  determines whether the IDR frame is the caption line Mn currently played back. Therefore, the control unit  11  determines whether the caption playback timing TMn of the caption line Mn is greater than the currently acquired elapse time (step S 254 ). 
     When the caption playback timing is greater than the currently acquired elapse time (step S 254 ; Yes), there is a possibility that the extracted IDR frame is to be played back before the currently displayed caption line Mn and corresponds to the caption line Mn. Thus the control section  11  stores the video position of the IDR frame (step S 255 ). Then, the process returns to step S 251 . 
     When the caption playback timing is less than the currently acquired elapse time (step S 254 ; No), the extracted IDR frame is played back immediately before the playback timing of the caption line Mn to correspond to the currently played caption line Mn. At this time, the control unit  11  reads the IDR frame from the video position PRn stored in step S 255 , and displays the IDR frame on the display panel  5  (step S 256 ). Then, the process returns to the one in  FIG. 8 , and is terminated. 
     When determining in step S 21  in  FIG. 8  that the mode is to be changed to the “normal view mode”, on the other hand, the control unit  11  advances the process to step S 26  to perform ordinary playback of a captioned video image without displaying a caption list. 
     The control unit  11  compares the caption playback timing TMn the currently played caption line Mn has with each video playback timing TRn in the seek-point management information  123  to specify the video playback timing TRn immediately before the caption playback timing TMn (step S 26 ). 
     Further, the video frame of a packet indicated by the video position PRn corresponding to the specified video playback timing TRn is played back (step S 27 ). In the example of  FIG. 5 , the video frame starts being played back from the IDR frame indicated by the video position PRn (number of TSP) associated with the video playback timing TRn. The control unit  11  also plays back the caption line Mn corresponding to the currently played video image (step S 27 ). 
     Subsequently, the control unit  11  performs the processes of steps S 29  to S 30  to play back the captioned video image. The control unit  11  starts measuring the elapse time with a timer (e.g., software timer in the control unit  11 ). When detecting elapse of a predetermined time (step S 29 ; Yes), the control unit  11  determines whether the currently played caption line is the last caption line in the content-recorded data  121 . When it is not the last caption line (step S 30 ; No), the process returns to step S 26 . When it is the last caption line (step S 30 ; Yes), the playback of the captioned video image is terminated. This is the end of the process of playing back a content while switching between the caption-with-list view mode and the normal view mode. 
     According to the embodiment, as described above, the user can adequately change over between the “caption-with-list view mode” and the “normal view mode” with a simple operation. In the caption-with-list view mode, it is possible to adequately select an arbitrary caption using the displayed caption list and display a video image corresponding to the selected caption. 
     In the normal view mode, a caption list is not displayed and various kinds of information can be displayed while using a small screen effectively. For example, a video image and a caption may be displayed using free space, or other information can be displayed. This makes it possible to keep the visibility improved well balanced by suppressing the amount of information to be displayed while keeping the operability at the time of selecting a caption. 
     Application Example 1-1 
     In the above-described embodiment, when the operation mode is switched, it may give an impression that a video image goes backward along the time axis, depending on how to select the point of starting video playback and a caption line to be played back. 
     This point will be described based on specific examples by referring to  FIG. 10 . 
       FIG. 10  is a diagram exemplifying display timings for video frames (IDRn and Pm) defined by a video PES and caption PES, and a caption line (Mn). 
     Suppose that the user has instructed to change over the mode to the “normal view mode” during playback of a caption line M 2  and an IDR frame I 2  in the “caption-with-list view mode”, for example. At this time, the control unit  11  starts playing back an IDR frame positioned directly before the caption line M 2  which has been played back before the mode change, i.e., from the IDR frame I 2 . 
     Further suppose that the mode change to the “caption-with-list view mode” has been instructed during playback of any video frame positioned between the IDR frame I 2  and a P frame P 4  after the mode change to the “normal view mode”. At this time, the control unit  11  plays back the caption line M 1  positioned directly before the playback timing of the video image which has been played back when the instruction has been given. Then, the control unit  11  starts playing back the video image from the IDR frame I 1  positioned before the caption line M 1 . 
     Accordingly, the viewer may feel that the display goes backward. This becomes noticeable when switching of the operation mode is carried out frequently. 
     To overcome the problem, a caption line having a playback timing later than the display time (playback timing) of the video image which has been displayed before the mode change should be displayed when the mode is changed from the “caption-with-list view mode” to the “normal view mode”. That is, when the user changes the view mode from the “caption-with-list view mode” to the “normal view mode”, the playback timing of the video image which has been displayed before the mode change should be specified in step S 28 , and a captioned video image having the latest playback timing later than the specified playback timing should be extracted in step S 30  to start playback. 
     Likewise, when the user changes the view mode from the “normal view mode” to the “caption-with-list view mode”, a caption line to be selected in step S 23  should be set to a caption line having the latest playback timing later than the playback timing specified in step S 22 , and the start point of a video image to be played back in step S 25  should be set to an independent frame whose playback timing is later than the playback timing of the caption line. 
     Referring to  FIG. 10 , for example, if a frame P 3  has been displayed when the mode is switched from the “normal view mode” to the “caption-with-list view mode”, the display time of the frame P 3  is discriminated in step S 28  in  FIG. 8 , playback of the video image is started from an independent video frame IDR 3  directly following the frame P 3  (step S 29 ) to play back the caption line M 2  directly after the frame P 3  (step S 30 ). 
     If the frame P 3  has been displayed when the mode is switched from the “caption-with-list view mode” to the “normal view mode”, the display time of the frame P 3  is discriminated in step S 23  in  FIG. 8 , the caption line M 2  directly following it is selected as a playback target (step S 23 ), and playback of the video image is started from the independent video frame IDR 3  (step S 25 ). 
     Accordingly, even when changeover of the view mode is repeated in a short period of time, it is possible to avoid that a caption line and video image are displayed returning along the playback timings during playback of a captioned video image. 
     According to the application example 1-1, as described above, when the view mode is changed over between the caption-with-list view mode and the normal view mode, a caption line having the latest playback timing later than the playback timing of the video image which has been displayed before the mode is changed. This makes it possible to avoid that through repeated changeover of the view mode, a caption line which has been displayed already is displayed again. 
     A video frame and a caption line which are to be selected at the time of changing the view mode are not limited to those in the above-described example, and can be adequately selected. 
     Application Example 1-2 
     A cell phone normally receives contents while changing the current position. This may bring about a case where depending on the position, the cell phone cannot receive broadcast waves well and the content-recorded data  121  is partially dropped off. 
     In an example of  FIG. 11 , for example, data of P frames P 21  to P 34 , data of I frames IDR 2  to IDR 6 , and data of caption lines M 1  to M 3  are dropped from the content-recorded data  121  in the time zone (data drop period TB) where contents drop. 
     Suppose that the user has instructed to change over the mode to the “caption-with-list view mode” when the content-recorded data  121  has been played back immediately after the data drop period TB in the “normal view mode”. At this time, a caption line which is in reproduction is a caption line M 4 . 
     The control unit  11  extracts an IDR frame directly before the caption line M 4  as a video image to be played back first after the mode change. Because a video frame does not exist in the data drop period TB, an I frame IDR 1  is extracted as the IDR frame positioned directly before the caption line M 4  and played back. In this case, a video image which does not match the content of the caption line M 4  in reproduction may be played back. 
     To overcome the problem, during reproduction of a content in the data drop period TB, a predetermined screen (e.g., screen filled with black) should be displayed in place of that video image. The following will describe the cell phone  1  according to an application example 1-2 which performs such an operation. 
     In the application example 1-2, the process of changing over between the caption-with-list view mode and normal view mode and playing back a content is basically identical to the process which has been explained referring to  FIG. 8 . It is to be noted however that in the application example 1-2 the control unit  11  executes processes of steps V 11  to V 13  shown in  FIG. 12  in place of step S 25  ( FIG. 9 ) in the “caption-with-list view mode”. 
     When executing the processes of steps S 21  to S 23  shown in  FIG. 8  and detecting the mode change to the “caption-with-list view mode”, the control unit  11  specifies a caption line to be played back. Next, the process goes to step V 11  in  FIG. 12 . The control unit  11  specifies an IDR directly before the specified caption line, acquires the display time for the IDR referring to the seek-point management information  123 , and acquires the difference between the caption display time TMn of the specified caption line and the video display time of the IDR frame directly before the caption display time (step V 11 ). 
     When the difference is equal to or greater than a predetermined value (e.g., 5 seconds) (step V 11 ; Yes), the control unit  11  displays a predetermined screen (e.g., screen filled with black, message showing that an image is dropped off) in place of the video image of the content-recorded data  121  (step V 12 ). Accordingly, even when data in the content-recorded data  121  is partly dropped off, it is possible to avoid that a video image which does not match the caption line in reproduction is displayed. 
     When the difference is smaller than the predetermined value, a video frame indicated by the video position PRn is displayed (step V 13 ). The process of step V 13  is the same as the corresponding one in  FIG. 9 . 
     According to the application example 1-2, as described above, when the data drop period TB is present in the content-recorded data  121  and is greater than a predetermined time, a predetermined screen is displayed instead of the video image of the content. This can prevent a video image which does not match the caption line in reproduction from being displayed. 
     Modifications 
     Although a list of captions is displayed to facilitate selection of a caption line in the foregoing description, the scheme of enabling selection of a caption line is optional. For example, an icon or a button corresponding to a caption line may be displayed and a caption line may be selected by selecting it. A list of captions may be hierarchized. Further, selection of a caption line may be accepted directly through an input from the keyboard. 
     In the case where the “caption-with-list view mode” is changed to the “normal view mode” in the example in  FIG. 8 , if the process of step S 25  has been terminated in the “caption-with-list view mode”, the processes of steps S 28  to S 29  need not be executed. In this case, playback should be started from the video image which has been displayed before the mode change. 
     The caption display time TMn is not limited to the playback start time for a captioned video image, but may be expressed by an arbitrary time as a reference. The caption display time TMn and the video display time TRn are not limited to the HMS unit or PTS (Presentation Time Stamp) unit, and may be expressed by an arbitrary unit. 
     In the “normal view mode”, a content may be played back without displaying a caption line. The cell phone  1  may be configured to have a fast forward capability as needed. 
     When the view mode is changed from the “normal view mode” to the “caption-with-list view mode”, the process of extracting a video frame from a video PES may not be executed, and the caption display time TMn in the caption management data  122  may be compared with the video display time TRn in the seek-point management information  123  and a video image of a TSP indicated by the video position PRn directly before the caption display time TMn. 
     Second Embodiment 
     A cell phone  1  according to a second embodiment of the present invention will be described below. 
     A cell phone  1  according to the embodiment has the same configuration as the one shown in  FIGS. 1 and 2 . 
     The operation of the cell phone  1  for playing back the caption lines will be described with reference to  FIGS. 13 to 32 . 
     In this embodiment, the cell phone  1  can display a plurality of images and corresponding caption lines in parallel. This display mode is called “multiple-video-display mode”. In this embodiment, the user selects the number of caption lines and video images to be displayed on the display panel  5  simultaneously by operating the display changeover button  4  or predetermined soft key. 
     The control unit  11 , like the one in the first embodiment, extracts information stored in the a caption PES (Packetized Elementary Stream) included in a TV signal after recording a content to generate caption management data  122 . The operation of generating the caption management data  122  is the same as the operation of creating the caption management data  122  in the first embodiment shown in  FIG. 6 . 
     The caption PES is packetized compressed coded data of a caption line and has information necessary to generate the caption management data  122 . In a specific example, when a TV signal is a TV signal SG shown in  FIG. 13 , a caption PES has information, such as caption lines Mn (n: 1 to N, N: the number of caption PESs included in the TV signal SG), caption playback timings TMn (n: 1 to N) and control codes CSn (n: 1 to N). 
     The “caption line” is data indicating the content of a caption line of a captioned video image. The “caption playback timing” is the timing of playing back a “caption line” represented by the PTS (Presentation Time Stamp) unit. In the example of the TV signal SG shown in  FIG. 13 , a plurality of caption playback timings TM 1  to TMN correspond to the timings (PTS unit) of playing back individual caption lines M 1  to MN. 
     The control code is a code which means separation of a caption line into predetermined units. In the example of the TV signal SG shown in  FIG. 13 , a plurality of control codes CS 1  to CSN correspond to the respective caption lines M 1  to MN and mean separation of each caption line. The control unit  11  extracts caption lines equal in number to the number of the control codes CSn (n: 1 to N) included in the TV signal SG. The operation of the control unit  11  to extract information from the caption PES and generate the caption management data  122  shown in  FIG. 6  will be described with reference to the example of the TV signal SG shown in  FIG. 13 . 
     As shown in  FIG. 6 , when starting generation of the caption management data  122 , the control unit  11  first attempts to extract a caption PES from the TV signal SG and determines whether a caption PES is present in the TV signal SG (step S 11 ). When a caption PES is not present (step S 11 ; No), the control unit  11  terminates generation of the caption management data  122 . 
     When a caption PES is present in the TV signal SG (step S 11 ; Yes), the control unit  11  extracts the caption PES (step S 12 ), then determines whether a caption line has been extracted from the information included in the caption PES (step S 13 ). When a caption line has been extracted (step S 13 ; Yes), the control unit  11  analyzes the caption PES and acquires information indicating the playback timing (PTS unit) of the caption line. 
     Subsequently, the control unit  11  subtracts a playback timing TR 1  of a top video image R 1  from a caption playback timing TM 1  of the first extracted caption line M 1  from the caption PES of the TV signal SG shown in  FIG. 13  to acquire an elapse time (PTS unit) from the beginning of the playback of the top video image R 1  to the playback timing of the caption line M 1  (step S 14 ). The elapse time (PTS unit) acquired is equivalent to the offset time when the playback timing of the top video image is set to a reference time  0 . 
     Subsequently, the control unit  11  converts the elapse time (PTS unit) acquired in step S 14  to the ordinary HMS unit (step S 15 ), and stores the elapse time (HMS unit) in the caption management data  122  as a caption display time TM 1  (step S 16 ). 
     As for the example shown in  FIG. 13 , the control unit  11  stores “00:00:00” resulting from conversion of the elapse time (PTS unit) acquired in step S 14  to the ordinary HMS unit (step S 15 ) in the caption management data  122  as the display time TM 1 . The display time of a caption line may be represented by the PTS unit without being converted to the HMS unit. 
     After storing the display time, the control unit  11  extracts a caption line to be stored in the caption management data  122  from the TV signal. Therefore, as shown in  FIG. 13 , the control unit  11  stores a sequence of characters (“Good morning. It is a nice day.”) separated directly before the control code CS 1  included in the first caption PES of the TV signal SG as the caption line M 1  in the caption management data  122  (step S 17 ). It is to be noted that when only the control code CS 1  is included in the TV signal SG, the control unit  11  stores all the caption lines included in the TV signal SG in the caption management data  122  as the caption line M 1 . 
     After storing the first caption line M 1 , the control unit  11  determines whether the last control code CSn in the TV signal SG has been reached (step S 18 ). When the last control code has not been reached (step S 18 ; No), the process returns to step S 11 . The control unit  11  extracts a next caption PES (step S 12 ) to acquire a caption playback timing (PTS unit) TM 2  located between the control code CS 1  and control code CS 2  in the TV signal shown in  FIG. 13 . After acquiring the caption playback timing (PTS unit) TM 2 , the control unit  11  subtracts the playback timing TR 1  of the top video image R 1  from the caption playback timing (PTS unit) TM 2  (step S 14 ), then convert the obtained elapse time into the HMS unit from the PTS unit (step S 15 ). 
     Then, the control unit  11  stores a resultant time “00:00:20” as a display timing TM 2  in the caption management data  122  (step S 16 ). 
     The control unit  11  also stores a sequence of characters included between the first control code CS 1  and the next control code CS 2  as a caption line M 2  of the caption management data  122  (step S 17 ). In the example of the TV signal SG shown in  FIG. 13 , the control unit  11  stores a sequence of characters “Hello.” located between the control code CS 1  and the control code CS 2 . The control unit  11  sorts the caption lines Mn (n: 1 to N) in an ascending order based on the display timing TMn (n: 1 to N). 
     The control unit  11  repeats the foregoing process until the last control code CSn in the TV signal SG is reached (step S 18 ; Yes) to generate the caption management data  122 . 
     When the user selects the “multiple video-display mode” by operating the display changeover button  4  or a predetermined soft key, the control unit  11  simultaneously displays and plays back a plurality of caption lines and individual video images to which playback timings corresponding to the playback timings of the respective caption lines are given, based on the generated caption management data  122 . Note that the multiple video-display mode to simultaneously display K (K strips) caption lines and individual video images is called “K-strip display mode”. 
     An operation of simultaneously playing back and displaying a plurality of caption lines and video images corresponding to the playback timings of the respective caption lines will be explained in a case of the “3-strip display mode”, as an example, of simultaneously displaying three caption lines and video images corresponding to the playback timings of the respective caption lines. 
     When the user selects the “3-strip display mode” by operating the display changeover button  4  or a predetermined soft key, the control unit  11  performs a process of allocating areas for displaying three caption lines and video images corresponding to the respective caption lines in the entire area on the display panel  5  to display individual pieces of data. This process will be described referring to  FIG. 14 . 
     First, the control unit  11  subtracts a pict area PA for displaying a pict icon and a soft-key area FA for displaying a soft key from a virtual display area D corresponding to the entire display panel  5 . 
     Next, the control unit  11  determines i) the size and position of a virtual area to be allocated as a caption area MA for displaying a caption line, and ii) the size and position of a virtual area to be allocated as a video area RA for displaying a video image, from the remaining area of the display area resulting from the subtraction of the pict area PA and the soft-key area FA therefrom. The caption area MA and video area RA are, for example, a caption virtual plane and video virtual plane in one-segment broadcasting. 
     While the scheme of acquiring the sizes of the caption area MA and video area RA is optional, the following scheme can be adopted as one example. The control unit  11  determines the size of the area needed to display a caption line based on the number of the characters contained in a caption line and the number of the vertical and horizontal pixels in font data. Alternatively, the control unit  11  determines the size of the area needed to display each video image from the number of the vertical and horizontal pixels of each video image. 
     After determining the sizes, the control unit  11  determines the locations to secure the caption area MA and video area RA in the display area D. While the scheme of acquiring the locations of the caption area MA and video area RA is optional, the following scheme can be adopted as one example. The control unit  11  determines the location of each area so that the caption area MA and video area RA do not overlap. When the locations of the caption area MA and video area RA are determined, the control unit  11  stores coordinate values (x, y) of the four vertexes of each of rectangles indicating the caption area MA and video area RA in the storage unit  12 . 
     Subsequently, the control unit  11  separates each of the caption area MA and video area RA into a plurality of areas according to the numbers of caption lines and video images to be displayed (“3” each in the “3-strip display mode”). The control unit  11  acquires a y coordinate value corresponding to two segment points when the vertical (y direction) width (y 2 −y 1 ) of the caption area MA is uniformly separated into three segments. The acquired y coordinate value becomes the y coordinate value of the four vertexes of the rectangle which define a caption area MA 2  shown in  FIG. 15 . 
     The control unit  11  combines a minimum value x 1  and a maximum value x 0  of the x coordinates on the caption area MA shown in  FIG. 14  with the y coordinate value of the two segment points acquired previously to determine the coordinates (x, y) of the four vertexes of the caption area MA 2  shown in  FIG. 15 . The control unit  11  sets two areas acquired by subtracting the caption area MA 2  from the caption area MA to the caption areas MA 1 , MA 3  shown in  FIG. 15 , respectively. At the time of separating the video area RA shown in  FIG. 14  into video areas RA 1  to RA 3  shown in  FIG. 15 , substantially the same scheme as adopted in separating the caption area MA into three segments may be used as well. 
     The caption area after separation is the area for displaying continual caption lines Mn registered in the caption management data  122 . In the example of the screen D 1  in the “3-strip display mode” shown in  FIG. 15 , the control unit  11  displays the caption line M 1  having the latest playback timing (display time TM 1 ) in the caption management data  122  shown in  FIG. 4  on the caption area MA 1 , and displays the caption line M 2  having the next latest display time TM 2  on the caption area MA 2 . The control unit  11  displays the caption line M 3  following the caption line M 2  on the caption area MA 3 . 
     The control unit  11  displays video images having playback timings corresponding to the playback timings of individual caption lines, displayed on the respective separated caption areas, on the respective separated video areas. In the example of the screen D 1  shown in  FIG. 15 , the control unit  11  displays video images R 1  to R 3  indicating the faces of a person as video images corresponding to the playback timings of the caption lines M 1  to M 3  on the separated video areas RA 1  to RA 3 . 
     To display individual video images corresponding to the caption lines current in reproduction on a plurality of video areas, the control unit  11  extracts video images (video frames) corresponding to the playback timings of the caption lines from the video signal in the TV signal SG. The following will describe the process of the control unit  11  to search content-recorded data (video data)  121  and display individual video images, displayed on the screen D 1  shown in  FIG. 15 , on the respective video areas. 
     When the user instructs to begin an application for viewing a captioned video image or select the “3-strip display mode” by operating the operational section  13 , the control unit  11  executes the process of a flow shown in  FIG. 16 . 
     In the process of  FIG. 16 , the control unit  11  acquires that number of video images which are to be displayed on the respective video areas on the display panel  5  (hereinafter “number of displayed video images”) from the content-recorded data  121  of the TV signal SG. The control unit  11  repeats the acquisition of video images and displays the acquired video images on the respective video areas until the number of acquired video images (hereinafter “acquired number”) reaches the “number of displayed video images”. 
     To start counting the “acquired number”, the control unit  11  first clears an acquired video image counter C to 0 (step S 1121 ). Then, the control unit  11  sets the number of video images to be acquired from the TV signal SG (hereinafter “number of video images to be acquired”) matches with the “number of displayed video images” (step S 1121 ). In the example of the screen D 1  in the “3-strip display mode” shown in  FIG. 15 , the number of displayed video images is “3”, and the control unit  11  sets the number of displayed video images to “3”. 
     Next, the control unit  11  extracts a video PES included in the video signal of the TV signal SG to specify the playback timing (PTS unit) of a video image corresponding to the display time of each caption line based on IDR frame information contained in the video PES. Therefore, the control unit  11  extracts the video PES from the video signal of the TV signal SG and extracts information of the topmost video frame in the TV signal SG (step S 1122 ). 
     The information on the video frame includes data on a video image and information indicating the playback timing at which the video image is to be played back. The information on the video frame is, for example, an IDR (Instantaneous Decoder Refresh) access unit or a non-IDR access unit in one-segment broadcasting. In a specific example, when the TV signal SG is a TV signal SG shown in  FIG. 13 , information on a video frame includes data on a video image (video frame) and information indicating the playback timing TR 1  for playing back the top video image R 1 . The playback timing TR 1  is expressed by the PTS unit. 
     The control unit  11  determines whether the extracted video frame is an IDR frame from the information extracted in step S 1122  (step S 1123 ). When the extracted video frame is not an IDR frame (step S 1123 ; No), the process returns to step S 1122 , and the control unit  11  extracts information on the next video frame from the TV signal SG to extract information on the topmost IDR frame. 
     When the currently extracted video frame is an IDR frame (step S 1123 ; Yes), the control unit  11  acquires an elapse time from the beginning of the playback of the top video frame to the playback of the IDR frame (step S 1124 ). At this time, the control unit  11  acquires the elapse time by subtracting the playback timing (TS unit) TR 1  of the video image R 1  at the top of the TV signal SG from the playback timing (PTS unit) the IDR frame has. The elapse time acquired in step S 1124  is the offset time until the time of the playback of the currently extracted video image when the playback timing of the top video image in the TV signal SG is set as a reference time  0 . 
     The control unit  11  determines whether the caption play back timing TM 1  of the caption line M 1  stored first in the caption management data  122  is greater than the elapse time acquired in step S 1124  (step S 1125 ). This determination process is performed to discriminate the possibility that the currently extracted IDR frame is a frame in which the caption line M 1  is referred to by the corresponding to video image R 1 . 
     When the display time of the caption line M 1  is greater than the elapse time from the beginning of the playback of the top video image till the playback timing of the currently extracted IDR frame (step S 1125 ; Yes), the currently extracted IDR frame is played back before the caption line M 1  and the video frame corresponding to the caption line M 1  may refer to the currently extracted IDR frame. Therefore, the control unit  11  saves the position of data of the video frame extracted in step S 1124  (e.g., address stored in the storage unit  12 ) (step S 1126 ). Then, the process returns to step S 1122 , and the control unit  11  further seeks video frames to extract information thereon. 
     The control unit  11  then subtracts the playback timing TR 1  of the topmost video image R 1  in the TV signal SG from the playback timing of the video frame extracted next, thereby acquiring the elapse time of the video frame extracted next. When the elapse time is smaller than the caption playback time TM 1  of the caption line M 1  too (step S 1125 ; Yes), the video frame is played back after the IDR frame extracted directly before and is played back before the caption line M 1 . Therefore, the control unit  11  stores the position of the data of the currently extracted video frame instead of the position of data on the video frame extracted directly before (step S 1126 ). 
     When the display time T 1  of the caption line M 1  is smaller than the elapse time from the beginning of the playback of the top video image till the playback timing of the currently extracted IDR frame (step S 1125 ; No), the currently extracted IDR frame is that of IDR frames to be played back earlier than the video image R 1  corresponding to the caption line M 1  whose playback timing is the closest to the playback timing of the video image R 1 . Accordingly, the control unit  11  stores the location saved in step S 1126  in the storage unit  12  as the location of the IDR frame which is referred to by the video image R 1  to be displayed on the video area RA 1  (step S 1127 ). 
     Then, the control unit  11  adds “1” to the acquired video image counter C to show that one video frame has been acquired (step S 1128 ). When the “acquired number” reaches the “number of video images to be acquired” set equal to the number of video images to be displayed on the video area as a result of adding 1 to the acquired video image counter C, no further extraction of a video image from the content-recorded data  121  is required thereafter. To make the determination, the control unit  11  determines whether the acquired video image counter C has reached the number of video images to be acquired (step S 1129 ). When the value of the acquired video image counter C has not reached the number of video images to be acquired (step S 1129 ; No), the process returns to step S 1122  and the control unit  11  further seeks video frames. 
     When the value of the acquired video image counter C has reached the “number of video images to be acquired” (3 in the 3-strip display mode) (step S 1129 ; Yes), the control unit  11  reads each video frame based on the positional information of the video data. The individual video frames to be read out are equivalent to the video images R 1  to R 3  displayed on the screen D 1  shown in  FIG. 15 . 
     Subsequently, the control unit  11  displays the video image R 1  read from the content-recorded data  121  on the video area RA 1  on the display panel  5  via the display unit  14 . The control unit  11  displays the video image R 2  having the next playback timing TR 2  to that of the video image R 1  in the content-recorded data  121  on the video area RA 2 , and displays the video image R 3  having the next playback timing TR 3  to that of the video image R 2  on the video area RA 3  (step S 11210 ). At this time, the control unit  11  performs the process of separating the video area RA to set the individual video areas RA 1  to RA 3  to display the video images R 1  to R 3  respectively by the above-described scheme. 
     The control unit  11  displays caption lines with playback timings TMn corresponding to the playback timings of video images to be displayed in the video areas in the caption areas MA 1 , MA 2 , MA 3 . In the example of the screen D 1  shown in  FIG. 15 , the caption lines M 1  to M 3  are displayed on the caption areas MA 1  to MA 3 . Through the foregoing process, it is possible to display a plurality of caption lines on the respective caption areas and video images corresponding to the individual caption lines on the video areas. 
     Next, a description will be given of an embodiment where each of individual caption lines and each of video images currently displayed are replaced with another caption line and another video image before being displayed on the respective caption area and video area, thus improving the usability. In the “3-strip display mode” explained above, if caption lines and video images currently displayed are fed strip by strip (one caption line) or are fed up or down strip by strip (1-strip scroll), the user can grasp the content occasionally, thus improving the usability. 
     In a case of scrolling the caption line and video image currently displayed on the respective caption area and video area strip by strip, a caption line Mn having the earlier or later playback timing TMn and a video image Rn corresponding to the caption line Mn should be displayed on the respective caption area and video area in place of the currently displayed caption line and video image. 
     As a specific example, a screen to be scrolled downward by one strip is a screen D 21  shown in  FIG. 17A . To display a screen D 22  shown in  FIG. 17B  in place of the screen D 21 , caption lines M 2  to M 4  having the next playback timings should be displayed on the caption areas MA 1  to MA 3  on the screen D 21  in place of the currently displayed caption lines M 1  to M 3 . Further, video images R 2  to R 4  corresponding to the caption lines M 2  to M 4  should be displayed on the video areas RA 1  to RA 3  in place of the currently displayed video images R 1  to R 3 . 
     Referring now to  FIG. 18 , the operation of scrolling caption lines displayed on the individual caption areas strip by strip will be explained. Suppose that caption lines to be displayed on the screens D 21  and D 22  are stored in the caption management data  122  shown in  FIG. 4  (the number of caption lines being N), and video images currently displayed on the caption area MA 1  are caption lines Mn (n: positive integer from 1 to N) positioned at the topmost position to the n-th position in the caption management data  122 . 
     When the user depresses the cursor key  3  downward (step S 131 ; Yes), the control unit  11  compares (N-n) with 2 to determines whether the caption line currently displayed on the caption area MA 3  is not the caption line MN (caption line having the last playback timing) stored last in the caption management data  122  (step S 132 ). When (N-n) is greater than 2 (step S 132 ; &gt;), the caption line currently displayed on the caption area MA 3  is not the caption line MN (caption line having the last playback timing) stored last in the caption management data  122 , the control unit  11  displays caption lines next to the currently displayed caption lines on the caption areas MA 1  to MA 3  in place of the currently displayed caption lines (step S 133 ). In a specific example, the caption lines M 1  to M 3  displayed on the screen D 21  in  FIG. 17A  are replaced with the caption lines M 2  to M 4  on the screen D 22  in  FIG. 17B . 
     The control unit  11  reads video images corresponding to respective caption lines newly displayed in step S 133  from the content-recorded data  121  and displays them on the respective video areas RA 1  to RA 3  (step S 134 ). In a specific example, the video images R 1  to R 3  displayed on the screen D 21  are replaced with the video images R 2  to R 4  on the screen D 22 . This completes the process of scrolling the display downward by one screen. 
     When (N-n) is 2 (step S 132 ; =), the caption line currently displayed on the caption area MA 3  is the caption line stored last in the caption management data  122 . In this case, the control unit  11  terminates the process, and keeps displaying the captions currently displayed on the caption areas MA 1  to MA 3  even when the user depresses the cursor key  3  downward. 
     When the user depresses the cursor key  3  upward (step S 135 ; Yes), upward scroll display is executed to display previous captions and video images strip by strip. 
     At this time, the control unit  11  compares (n−1) with 0 in order to discriminate whether the caption line Mn displayed on the topmost caption area MA 1  is the caption line M 1  the top caption line M 1  in the caption management data  122 . 
     When (n−1) is greater than 0 (step S 136 ; &gt;), the caption line Mn displayed on the caption area MA 1  is not the top caption line M 1 . At this time, the control unit  11  displays caption lines given with display times preceding by one to the currently displayed caption lines on the caption areas MA 1  to MA 3  (step S 137 ). Further, the control unit  11  reads video images corresponding to the caption lines newly displayed in step S 137  from the content-recorded data  121 , and displays the video images on the video areas RA 1  to RA 3 . 
     Specifically, in a case where when the screen D 22  shown in  FIG. 17B  is displayed, when the user depresses the cursor key  3  upward, the process of step S 137  allows the caption lines M 1  to M 3  to be displayed on the caption areas MA 1  to MA 3  in place of the currently displayed caption lines M 2  to M 4 . Further, the process of step S 138  allows the video images R 1  to R 3  corresponding to the playback timings of the caption lines M 1  to M 3  are displayed on the video areas RA 1  to RA 3  in place of the currently displayed video images R 2  to R 4 . Accordingly, the screen D 21  shown in  FIG. 17A  is displayed. 
     When (n−1) is 0 in step S 136  (step S 136 ; =), the caption line currently displayed on the caption area MA 1  is the top caption line M 1  in the caption management data  122 . At this time, the control unit  11  keeps displaying the caption lines M 1  to M 3  currently displayed on the caption areas MA 1  to MA 3  even when the user depresses the cursor key  3  upward. The foregoing operation can allow caption lines and video images corresponding to the caption lines to be scrolled by one strip when the user depresses the cursor key  3  upward or downward. 
     The contents of the foregoing processing of the flow of the one-strip scroll is partly changed and individual caption lines currently displayed are all replaced with caption lines located preceding or succeeding by the number of displayed video images (3 in the 3-strip display mode)” starting from each caption line. At this time, the screen can be scrolled as if pages of a book were turned (this operation will be hereinafter called “page flipping”). 
     Hereinafter, the operation of displaying individual caption lines and video images given with playback timings later by the “number of displayed video images” in place of the currently displayed caption lines and video images is called “page feeding”. The operation of displaying individual caption lines and video images given with playback timings earlier by the “number of displayed video images” in place of the currently displayed caption lines and video images is called “page back”. The process in which the cell phone  1  executes “page flipping” will be described in the case of the “3-strip display mode” as an example. 
     As shown in  FIG. 20 , the control unit  11  determines whether the cursor key  3  is depressed rightward to discriminate if “page feeding” has been instructed by the user (step S 141 ). When there is such an instruction (step S 141 ; Yes), the control unit  11  determines whether any one of the caption lines from the last one to the third one from the last is currently displayed on each of the caption areas MA 1  to MA 3  to discriminate “page feeding” is enabled or disabled (step S 142 ). When such a caption line is not currently displayed (step S 142 ; No), the control unit  11  displays caption lines given with the playback timings later by 3 than the currently displayed caption lines on the caption areas MA 1  to MA 3  in place of the currently displayed caption lines (step S 143 ). The control unit  11  also displays video images corresponding to the caption lines displayed on the caption areas MA 1  to MA 3  on the video areas RA 1  to RA 3 , respectively (step S 144 ). 
     Transition of the screen on the display panel  5  when “page feeding” is carried out will be explained specifically. Suppose that a screen to be subjected to “page feeding” is a screen D 31  shown in  FIG. 19A . The video images R 1 , R 2 , R 3  are displayed on the video areas RA 1 , RA 2 , RA 3  while the caption lines M 1 , M 2 , M 3  are displayed on the caption areas MA 1 , MA 2 , MA 3 . 
     When the user depresses the cursor key  3  rightward, the control unit  11  displays caption lines M 4  to M 6  given with playback timings set later than the caption lines M 1  to M 3  by the “number of displayed video images (3)” on the caption areas MA 1  to MA 3 , and displays the video images R 4  to R 6  on the video areas RA 1  to RA 3 . Thereafter, every time the user depresses the cursor key  3  rightward, pages for the caption lines and the video images corresponding thereto are fed. 
     In case of returning page, the control unit  11  determines whether the user has depressed the cursor key  3  leftward in step S 145  shown in  FIG. 20 . When such depression has occurred (step S 145 ; Yes), the control unit  11  determines whether the caption line Mn displayed on the topmost caption area MA 1  is the caption line M 1  given with the top display time in the caption management data  122  (step S 146 ). 
     When the caption line Mn is not the top caption line M 1  (step S 146 ; No), page back is possible. At this time, the control unit  11  reads individual caption lines given with playback timings set earlier than the currently displayed caption lines by the “number of displayed video images (3)” from the caption management data  122 , and displays the caption lines on the caption areas MA 1  to MA 3  (step S 147 ). Further, the video images corresponding to the individual caption lines displayed on the caption areas MA 1  to MA 3  are displayed on the video areas RA 1  to RA 3 , respectively, so that page is fed backward (step S 148 ). 
     The foregoing operation enables “page flipping (page feeding or page back). The screen changeover method in “page flipping” is not limited to the rightward or leftward depression of the cursor key  3 , but may be the operation of a soft key or the like displayed on the soft-key area FA by operating the operational section  13 . 
     An embodiment for improving the user&#39;s convenience regarding “display of caption line” will be described next. When the number of characters contained in a caption line in a content is greater than the number of characters displayable on the caption area, the foregoing embodiment ranges a problem that even when the caption line is displayed on the caption area, the caption line breaks in midway and is not fully displayed. 
     To overcome the problem, for example, the caption area should be enlarged to make the number of the characters displayable on each caption area larger than the number of the characters than the number of the characters contained in a caption line in a content. The following will describe the operation of enlarging the caption area to display a caption line containing a greater number of characters than the number of characters displayable on each caption area (hereinafter “long caption line”) when the number of characters to be displayed on each caption area is greater than the number of characters displayable on the caption area (hereinafter “number of displayable characters”). 
     As shown in  FIG. 23 , when the user selects an arbitrary caption line with the cursor key  3 , the control unit  11  acquires the number of characters in the selected caption line (step S 151 ), and determines whether the number of characters is greater than the “number of displayable characters” (step S 152 ). When the acquired number of characters of the caption line is equal to or less than the “number of displayable characters” and the caption line can be displayed on the currently secured caption area (step S 152 ; No), the process is terminated. 
     When the acquired number of characters of the caption line is a “long caption line” and the number of characters contained therein is larger than the “number of displayable characters” (step S 152 ; Yes), the content of the caption line cannot be fully displayed on the currently secured caption area. To show that the “long caption line” has a continuous part, the control unit  11  acquires the “number of displayable characters” from the top of the “long caption line”, displays the characters on the caption area, and displays a mark prompting to display hidden characters in the “long caption line” on the caption area (step S 153 ). 
     A specific example of the screen displayed at step S 153  when the caption line selected by the user is a “long caption line” will be explained. If the screen displayed when the user has selected the “long caption line” is a screen D 41  shown in  FIG. 21 , the caption line M 2  displayed on the caption area MA 2  is a “long caption line M 2 ” containing a larger number of characters than the displayable number of characters, and cannot therefore be fully displayed on the current caption area MA 2 . 
     At this time, the control unit  11  displays the “number of displayable characters” from the top of the “long caption line M 2 ” on the caption area MA 2 . In addition, the control unit  11  displays a mark (“←”) for prompting the user to display hidden characters in the “long caption line M 2 ”. 
     Then, the control unit  11  stands by until the user&#39;s operation of the operational section  13  is detected. When such an operation is detected, the control unit  11  determines whether the operation instructs to display all the characters in the “long caption line” (step S 154 ). The instruction to display all the characters may be executed as a display settle key (not shown) is depressed. When the user&#39;s operation is not an instruction to display all the characters (step S 154 ; No), the process is terminated. When the operation instructs to display all the characters (step S 154 ; Yes), the control unit  11  computes the size of the caption area needed to display the selected “long caption line” (step S 155 ). 
     The process of step S 155  will be explained specifically. Suppose that the user has operated the cursor key  3  to have selected the caption area MA 2  on the screen D 41  shown in  FIG. 21 . At this time when the user consecutively operates the operational section  13  to instruct to display all the characters of the “long caption line”, the control unit  11  acquires the number of characters ( 20 ) in a caption line (“Good afternoon. Cheer up today.”) stored in the caption management data  122 . Further, the control unit  11  multiplies a value equal to or slightly greater than the acquired number of characters by the size of pixels of font data of each character (the number of vertical characters×the number of horizontal characters) to acquire the size of the caption area that can display the entire number of characters of the “long caption line”. 
     Then, the control unit  11  secure the caption area for displaying a “long caption line” on the display area according to the acquired size (step S 156 ). The control unit  11  then displays the entire “long caption line” on the caption area (step S 157 ). This is the end of the process of enlarging and displaying the caption area. 
     An example of the screen which is allowed by the process of step S 157  to show the entire “long caption line” on the caption area with the size tended by the process of step S 156  will be described. In the example of a screen D 42  shown in  FIG. 22A , the control unit  11  avoids overlapping of the caption area MA 2  with the caption areas MA 1  and MA 3 , and extends only the horizontal size of the caption area MA 2  while keeping the vertical size of the caption area MA 2  constant to secure the required area, so that the user can see all the caption lines M 1  to M 3 . 
     In the example of a screen D 43  shown in  FIG. 22B , the control unit  11  avoids overlapping of the caption area MA 2  with the video area R 2 , and extends only the vertical size of the caption area MA 2  while keeping the horizontal size of the caption area MA 2  constant to secure the required area, so that the user can see the entire caption line M 2  and each of the video images R 1  to R 3 . At this time, a caption line is not displayed on the caption areas MA 1 , MA 3  other than the caption area showing the “long caption line”. When the state where the screen D 42  shown in  FIG. 22A  and screen D 43  shown in  FIG. 22B  is returned to the state where the screen D 41  before size extension shown in  FIG. 21 , the termination of the display of the entire “long caption line” should be instructed by depression of the settle key or the operation of the operational section  13  or the like. 
     Application Example 2-1 
     Next, an application example for improving the user&#39;s convenience regarding “display of video image” at the time of playing back a content will be described. 
     First, a description will be given of an embodiment which allows the user to grasp the relation between previous and succeeding contents more easily by increasing the number of video images to be simultaneously displayed on video areas with the same size. 
     In general, there are video images with the ratio of the horizontal size to the vertical size (aspect ratio) of 4:3 (hereinafter “normal video image”) and video images with the aspect ratio of 16:9 (hereinafter “lateral video image”) as the types of video images to be TV broadcast. 
     As a specific example, normal video images are normal video images R 1 , R 2 , R 3  shown in  FIG. 24A , while lateral video images are lateral video images Y 1 , Y 2 , Y 3 , Y 4  shown in  FIG. 24B . The size of each of the normal video images R 1  to R 3  is 240 vertical pixels×320 horizontal pixels, and the size of each of the lateral video images Y 1  to Y 4  is 180 vertical pixels×320 horizontal pixels. Suppose that a video area having the vertical size of 720 pixels and the horizontal size set equal to the horizontal size (320 pixels) of the normal video images R 1  to R 3  and the lateral video images Y 1  to Y 4  is secured. The three normal video images R 1  to R 3  can be displayed in series vertically on the secured video area as seen on a screen D 51  shown in  FIG. 24A . Further, the four lateral video images Y 1  to Y 4  can be displayed in series vertically on the secured video area as seen on a screen D 52  shown in  FIG. 24B . 
     That is, when a video area having a vertical size which has both the vertical size of normal video images and the vertical size of lateral video images as common divisors is secured, a larger number of lateral video images than normal video images can be displayed simultaneously, so that the user can view a larger number of video images. The same is applied to the horizontal size of video areas. 
     A description will now be given of the process of displaying a screen in the “3-strip display mode” when video images read from the content-recorded data  121  are normal video images, and displaying a screen in the “4-strip display mode” when video images read from the content-recorded data  121  are lateral video images. It is premised that the control unit  11  has secured a video area having a vertical size of 720 pixels and a horizontal size of 320 pixels on the display area of the display panel  5  when the process is invoked. 
     As shown in  FIG. 25 , when the user operates the operational section  13  to instruct initiation of an application for viewing a captioned video image or selection of the multiple video-display mode, the control unit  11  starts the screen setting process. After the process has started, the control unit  11  acquires the sizes of video images read from the content-recorded data  121  based on the vertical and horizontal pixels or the like (step S 161 ). 
     After the acquisition, the control unit  11  acquires the aspect ratio of the sizes of the video images read from the content-recorded data  121 , determines that the video images are lateral video images when the aspect ratio is 16:9 (step S 162 ; Yes) and sets the “number of displayed video images” to 4 (step S 163 ). 
     Then, the control unit  11  divides the vertical size (720 pixels) of the secured video area on the display area by the “number of displayed video images” set in step S 163  to divide the secured video area into four video areas RA 1  to RA 4  each having 180 vertical pixels and 320 horizontal pixels aligned in series vertically (step S 165 ). 
     The control unit  11  divides the caption area according to the separated video areas (step S 166 ). The control unit  11  displays the lateral video images Y 1  to Y 4  on the respective video areas separated in step S 165 , and displays caption lines corresponding to the video areas on the respective caption areas separated in step S 166 . At this time, the screen D 52  shown in  FIG. 24B  is displayed on the display panel  5 . 
     When the aspect ratio of the sizes of the video images is 4:3, the control unit  11  determines that the video images are normal video images (step S 162 ; No) and sets the “number of displayed video images” to 3 (step S 164 ). Then, the control unit  11  divides the vertical size of the video area by 3 to divide the secured video area into three video areas RA 1  to RA 3  each having 240 vertical pixels and 320 horizontal pixels aligned in series vertically (step S 165 ). The control unit  11  also divides the caption area according to the separated video areas (step S 166 ). The control unit  11  displays the normal video images R 1  to R 3  on the respective video areas separated in step S 165 , and displays caption lines corresponding to the video areas on the respective caption areas separated in step S 166 . At this time, the screen D 51  shown in  FIG. 24A  is displayed on the display panel  5 . 
     Through the foregoing process, individual video images are displayed according to the type (lateral video image or normal video image) of the video images in the content, and a larger number of video images than those normal video images can be displayed when the video images are lateral video images. In this embodiment, i) 1-strip scroll, ii) page flipping, and iii) display of a longer caption line than is allowed by the number of displayable characters can be applied. 
     The foregoing description of the embodiment has been given of the case of the display mode of displaying a plurality of video images in series vertically. However, the cell phone  1  according to the embodiment can change the display positions of the caption areas and the video areas, and display caption lines and video images in various layouts. 
     The following will describe a modification of the embodiment where four caption lines and individual video images respectively corresponding to the caption lines are arranged in a lattice pattern. It is to be noted that the operational state of displaying caption lines and video images corresponding thereto both arranged in a lattice pattern is called “lateral display mode” while the operational state of displaying caption lines and video images corresponding thereto both aligned in series vertically a lattice pattern is called “longitudinal display mode”. 
     Like a display screen D 6  shown in  FIG. 26 , the screen that is displayed in the “lateral display mode” has individual lateral video images Y 1  to Y 4  arranged in a lattice pattern on the display area of the display panel  5  with the lengthwise direction of the display area matching with the lengthwise direction of each of the lateral video images Y 1  to Y 4 . The screen that is displayed in the “longitudinal display mode” is the screen D 1  shown in  FIG. 15 . The user can change over the view mode between the “longitudinal display mode” and the “lateral display mode” by operating the operational section  13 . 
     The following will describe the process of setting the screens that are compatible with the “longitudinal display mode” and the “lateral display mode”. As shown in  FIG. 27 , the control unit  11  acquires the display direction of a video image in a content with respect to the lengthwise direction of the display area (hereinafter called “lateral direction”) (step S 171 ). At this time, the control unit  11  acquires the display direction of a video image based on information on the resolution included in the video signal of the TV signal SG. The information on the resolution is, for example, “320 pixels×180 pixels×16 bits” in case of the video virtual plane of a lateral video image in one-segment broadcasting. 
     Subsequently, the control unit  11  determines whether the acquired display direction of a video image matches with the lateral direction of the display area (step S 172 ). When the display direction of a video image matches with the lateral direction of the display area (step S 172 ; Yes), the control unit  11  sets the number of video images to be acquired (number of video images to be acquired) from the content-recorded data  121  to 4 (step S 173 ). After the setting, the control unit  11  executes the process of setting the display screen in the “lateral display mode”. 
     The control unit  11  secures an area to be allocated as a caption area and a video area onto the display area to ensure the lattice arrangement of the individual video areas and caption areas in setting the lateral arrangement of the video areas (step S 174 ) and setting the arrangement of the caption areas to match with the arrangement of the video areas (step S 175 ). After securing the display area, the control unit  11  separates the display area at the longitudinal center position and the lateral center position into four areas arranged in a lattice pattern. 
     The present invention arranges the individual video images in each separated area in the display direction determined in step S 171 , and sets each arranged area to a video area (step S 174 ). Specifically, for example, the video areas after the setting are the four video areas RA 1  to RA 4  on the screen D 6  shown in  FIG. 26 . 
     The control unit  11  sets the remaining areas after subtracting the individual video areas set in step S 175  from the separated areas to the individual caption areas (step S 175 ). Specifically, for example, the caption areas after the setting are the four caption areas MA 1  to MA 4  on the screen D 6  shown in  FIG. 26 . Then, the control unit  11  displays, on the respectively caption areas, individual caption lines corresponding to the playback timings of individual video images displayed on the respective video areas. 
     When the display direction of a video image matches with the longitudinal direction of the display area (step S 172 ; No), the control unit  11  sets the “number of video images to be acquired” to 3 (step S 176 ), and executes the process of setting the screen for the “longitudinal display mode”. At this time, the control unit  11  uniformly separates the longitudinal directional size of the screen D 6  into three so that individual video areas and individual caption areas are arranged in series vertically on the display panel  5 . The contents of the processes of subsequent steps S 177  and S 178  are substantially identical to those of steps S 174  and S 175 . 
     Through the foregoing processes, the screens that are compatible with the “longitudinal display mode” and the “lateral display mode” can be set. The screen setting process can automatically set the screens in “longitudinal display mode” and “lateral display mode” according to the display direction of video images of a content, when activated before the flow shown in  FIG. 16  as the user operates the operational section  13  to instruct initiation of an application for viewing a captioned video image or selection of the multiple video-display mode. In this embodiment, 1-screen scroll, page flipping, and enlargement of caption areas in the “long caption line” display mode can be applied. 
     A description will now be given of an embodiment of improving the user&#39;s convenience when “video images of different contents” are displayed on the display panel  5 . When video images of a plurality of contents are displayed on the display panel  5  at the same time, the user has a difficulty in determining whether individual video images are contained in the same content or different contents. 
     To determine whether individual video images are contained in the same content or contained in different contents when a plurality of video images are displayed on the display panel  5 , titles should be given to the individual contents to discriminate whether a plurality of video images are contained in the same content or not. 
     The fundamental configuration of the cell phone  1  for achieving the operation in a titled display mode is the same as the configuration shown in  FIG. 2 , except that the storage unit  12  shown in  FIG. 2  stores caption management data  122  and content-recorded data  121  each of which corresponds to a plurality of contents. 
     The storage unit  12  stores contents list data  124 . The contents list data  124  includes items, such as “title TL”, “recording date TT”, and “genre TJ” as exemplified in  FIG. 28 , which are associated with the each content. 
     The “title TL” is an item indicating a title given to each content. The “recording date TT” is an item indicating a period from the date and time on which recording of each content has started and the date and time on which the recording has ended. The “genre TJ” is an item indicating a field in which each content is categorized according to the content, such as news, sports or drama. Information to be stored in the genre TJ can be acquired from, for example, EIT (Event Information Table) or the like in one-segment broadcasting. 
     The user can select a content given with a “title TL” by operating the operational section  13 . The control unit  11  reads the title TL of the content selected by the user from the contents list data  124 , and displays the title TL on the display panel  5  via the display unit  14 . A specific example of the screen on which the title TL read from the contents list data  124  is displayed (hereinafter “titled screen”) on a screen D 71  shown in  FIG. 29A . 
     In case of displaying a titled screen D 71 , a title area TA for displaying a title TL 1  of a content selected from the contents list data  124  and currently played back is provided at the lower left portion of the display area on the display panel  5 , and the title TL 1  (“story of moon”) is displayed in the title area TA. The content with the title TL 1  has the latest recording date TT in the contents list data  124  shown in  FIG. 28 . 
     The video areas RA 1  to RA 3  arranged in series in the vertical direction are provided in the center portion of the display area, and video images R 11  to R 13  corresponding to the title TL 1  currently displayed in the title area TA are displayed. Further, caption lines M 11  to M 13  having playback timings corresponding to the video images R 11  to R 13  are displayed on the caption areas MA 1  to MA 3 . 
     When a video image is displayed in a predetermined area defined by a rectangle, it is likely that displaying the video image near the center portion of the predetermined area provides a better visibility for a user. In this respect, the control unit  11  sets the video areas RA 1  to RA 3  where a plurality of video images of the content currently played back are displayed in such a way that the video areas RA 1  to RA 3  are vertically arranged in series in the vicinity of the lateral center position of the display area. 
     A video area RA 4  for displaying a video image in a content with the latest recording date TT in the contents list data  124  shown in  FIG. 28  is provided in the left center of the display area. It is to be noted that because the latest content (content with the title TL 1 ) is currently played back in the example of  FIG. 29A , a video image R 22  of a content (title TL 2  (“bird walk”)) with the next latest recording date TT is displayed in the video area RA 4 . 
     A video area RA 5  for displaying a content with the oldest recording date TT in the contents list data  124  is provided in the right center of the display area, and a video image R 32  of a content with a title TL (“drive in car”) is displayed in the video area RA 5 . A video image to be displayed in the video area RA 4 , RA 5  is optional, and may be the first IDR frame of the content, a video image corresponding to a top caption line in the caption management data  122 , or the like. 
     With the screen D 71  displayed on the display area, the user can select another content instead of the currently displayed content by depressing the cursor key  3  leftward or rightward. At this time, the control unit  11  displays a video image in the content selected by the user and displays the title TL given to the content in the title area TA. A description will now be given of the process of switching the display of the title TL in the case as an example where the control unit  11  changes over the screen to be displayed on the display panel  5  from the screen D 71  shown in  FIG. 29A  to a screen D 72  shown in  FIG. 29B  in response to the user&#39;s depression of the cursor key  3 . 
     As shown in  FIG. 30 , the control unit  11  stops playing back the content in the contents list data  124  whose title TL is currently displayed in the title area TA in response to the user&#39;s leftward depression of the cursor key (step S 181 ; Yes). Accordingly, the display of the individual video images in the respective video areas RA 1  to RA 3  provided vertically in series in the center portion of the display area is terminated (step S 182 ). Subsequently, the control unit  11  starts playing back a content containing the video image R 42  currently displayed in the video area RA 4  provided in the left center of the display area (step S 183 ). 
     As playback of a content starts, the control unit  11  reads the title TL 2  of the content whose playback has started from the contents list data  124 , and displays the title TL 2  in the title area TA (step S 184 ). 
     The control unit  11  displays caption lines M 21  to M 23  of the content with the title TL 2  whose playback has started in the respective caption areas MA 1  to MA 3  (step S 185 ), and displays the video images R 21  to R 23  corresponding to the playback timings of the caption lines M 21  to M 23  in the respective video areas RA 1  to RA 3  located in the center of the display panel  5  (step S 186 ). As a result, the titled screen D 72  shown in  FIG. 29B  is displayed. 
     With the titled screen D 72  displayed on the display panel  5 , when the user depresses the cursor key  3  rightward (step S 187 ; Yes), the control unit  11  terminates the playback of the content currently played back with the title TL 2  or the playback of the content currently displayed in the video areas RA 1  to RA 3  (step S 188 ). Then, the control unit  11  starts playing back the content whose video image R 32  is displayed on the video area RA 5  provided in the right center of the display area (step S 189 ), and executes substantially the same processes as the processes of steps S 184  to S 186  explained above (step S 1810  to S 1812 ) to display the titled screen D 71  shown in  FIG. 29A . This is the end of the process of displaying a titled screen. 
     An embodiment for improving the user&#39;s convenience regarding “display of video image” will be described next. In the foregoing embodiment, areas of the same sizes are allocated as video areas to display respective video images at a time. 
     With video areas of the same sizes being secured to display a plurality of video images, even if the video images include a video image to which the user directs his/her attention (e.g., video image of a scene which is currently played back), this video image is displayed in the same size as the other video images. To overcome the shortcoming, the video area, where the video image to which the user pays his/her attention is displayed, may be enlarged to magnify the video image to be displayed. 
     The following will be described the operation of the control unit  11  to enlarge and display a video image in a content selected by the user&#39;s operation and currently displayed. The operational state where a video image currently played back is enlarged and displayed is called “video zoom-up display mode”. 
     In the video zoom-up display mode, as shown in  FIG. 32 , when the user selects a video image displayed in the center of the screen D 71  shown in  FIG. 29A  by operating the operational section  13 , the control unit  11  enlarges the video area RA 2  to newly secure a large video area RA 6  as seen from a screen D 8  shown in  FIG. 31  and arranges the video area RA 6  in the center portion of the display area (step S 191 ). The reason why the enlarged video area RA 6  is arranged in the center position of the screen D 8  in the video zoom-up display mode is that the location near the center portion improves the visibility for the user on the display area defined by a rectangle. Subsequently, the control unit  11  enlarges the video image of the scene of the content selected by the user and currently played back, and displays the video image on the display panel  5  via the display unit  14  (step S 192 ). 
     Next, the control unit  11  determines whether there is any caption line in the caption lines displayed on the caption areas MA 1  to MA 3  to which the next display time is given (step S 193 ). When there is no such caption line (step S 193 ; No), the control unit  11  terminates the video zoom-up display process. When there is such a caption line (step S 193 ; Yes), on the other hand, the control unit  11  reads each caption line to which the next display time is given (step S 194 ), and detects a video image corresponding to the display time of each caption line (step S 195 ). The scheme of detecting such a video image is substantially the same as the foregoing scheme described referring to  FIG. 16 . 
     When reading caption lines and detection of a video image are completed, the control unit  11  starts the timer (not shown) to measure the time, and detects that a predetermined time has elapsed (step S 196 ). The time is measured by the timer to detect that the playback timing TMn of the caption line Mn stored in the caption management data  122  is reached. 
     When detecting elapse of the predetermined time (step S 196 ; Yes), the control unit  11  displays caption lines in the caption areas MA 1  to MA 3  (step S 197 ), and displays individual video images corresponding to the playback timing TMn of the respective caption lines displayed in step S 197  in the enlarged video area RA 6  (step S 198 ). That is, video images in the content with the title TL 1  are sequentially displayed on the video area RA 6  according to the playback timings of the caption lines. 
     Thereafter, the control unit  11  repeats executing the foregoing process until the last caption line MN relating to the content in the caption management data  122  is reached (step S 193 ; No). This completes the process of playing back and displaying caption lines included in the content while playing back and displaying video images in the content on the enlarged video area. 
     According to the embodiment, as described above, a plurality of caption lines with display times can be played back and displayed on the display panel  5 , and video images associated with the display times given to the individual caption lines can be played back and displayed. Accordingly, the user can view a caption line of the present playback scene of a captioned video image and caption lines and video images which are to be played back before and after the captioned video image, thus making it easier for the user to grasp the contents of the captioned video image. 
     According to the operation of the user, the cell phone  1  of the embodiment changes the display of caption lines currently displayed on the display panel  5  and video images corresponding to the respective caption lines with the display of those caption lines and video images corresponding thereto which precede or follow the currently displayed caption lines and video images by one, thereby achieving “1-strip scroll” of captioned video images. This can allow the user to view a video image ahead of the playback timing given to a currently displayed video image or view a video image which is to be played back after the currently displayed video image. 
     According to the embodiment, according to the user&#39;s operation, a currently displayed caption line and a video image corresponding to each caption line are changed over with a caption line and a video image corresponding thereto which are to be played back before or after by a predetermined timing in the caption management data  122 , and displayed accordingly, thus achieving “page flipping” of captioned video images. This can allow the user to check the contents of multiple video images at the same time and find caption lines or video images of captioned video images or video images quicker than is achieved by the “1-strip scroll”. 
     According to the embodiment, when a caption line containing more characters than are displayable in the caption area is assigned to the caption area, the control unit  11  increases the size of the caption area and displays all the characters contained in the caption line in response to the user&#39;s operation. This permits the user to read the entire caption line even if the caption line contains a larger number of characters than are displayable in the currently secured caption area, thus improving the user&#39;s convenience. 
     According to the embodiment, when the size of a caption area is increased, the size-increased caption area is arranged so that it does not overlie other caption areas or video areas. Accordingly, the user can read the entire caption line whose characters could not be fully displayed before the enlargement, without missing the display of a caption line preceding or following the caption line which contains a larger number of characters than are displayable in the caption area, and a video image corresponding to each caption line. 
     According to the embodiment, the number of video images to be displayed on a video area to show individual video images is changed according to the type of video images in a content (“lateral video image” or “normal video image”). Particularly, when video images to be displayed are “lateral video images”, a larger number of video images can be displayed than the number of “normal video images” that are displayed on the screen at the same time. This can allow the user to obtain a greater amount of information when video images in a content to be viewed is “lateral video images” as compared with the case of viewing a content containing “normal video images”. 
     According to the invention, even when video images of different contents are displayed simultaneously, the title of a content whose video image is currently selected by the user is displayed in the title area TA. This allows the user to distinguish video images in the currently selected content from those of other contents and check video images of other contents. 
     According to the embodiment, a content, selected by the user from video images currently displayed on the display panel  5  simultaneously, is played back and displayed as a captioned video image. Accordingly, the user can easily grasp what is inside the content containing the selected video image with the help of captioned display, and distinguish the currently played content from other contents. 
     According to the embodiment, the video image of the current playback scene of the content currently in reproduction is displayed in the video area located in the center portion of the display area. Because the visibility of video images is improved at this time, the video area where the video image of the currently played scene is displayed is set larger than other video areas. This improves the visibility of video images and makes it easier for the user to recognize that a content containing the enlarged video image is selected. 
     Modifications of the embodiment will be described below. In case of displaying a “long caption line” entirely, caption lines are not displayed on the caption areas MA 1  and MA 3  other than the caption area displaying the “long caption line” in the example of the screen D 43  shown in  FIG. 22B , which is not restrictive, and caption lines may be displayed on the caption areas MA 1 , MA 2 . 
     In the case where “video images of multiple contents” are simultaneously displayed, only the title of the content currently in reproduction is displayed in the title area TA on the titled screen D 71  shown in  FIG. 29A , which is not restrictive, and the titles of other contents currently displayed may also be displayed in the title area TA. 
     Not only the title of a content currently in reproduction but also a list indicating a title TL of a content stored in the contents list data  124  preceding or succeeding the currently played content by a predetermined number may be displayed in the title area TA on the titled screen D 71 . 
     A predetermined time which is measured by the timer may be set arbitrarily by the user or may be set larger by the control unit  11  as the number of characters contained in a caption line to be displayed becomes greater. 
     In the “video zoom-up display mode”, the user may be allowed to terminate the zoom-up display currently selected on the screen D 8  in  FIG. 31  and return to the display of the screen D 71  in  FIG. 29A . 
     Third Embodiment 
     The operation of a cell phone  1  according to a third embodiment of the invention will be described below. 
     During reproduction of a captioned video image, the cell phone  1  of the embodiment simultaneously displays the captioned video image and a caption list showing a plurality of caption lines. Further, when the elapse of a prescribed “caption changeover time” is detected by a timer, a caption line to be played and displayed is replaced with a caption line to be displayed in the caption list. 
     The replacement of the caption line is automatically executed without involving the operation by the user, and the caption line that has been displayed in the caption list before replacement is scrolled (hereinafter “auto scroll”). The user can instruct the initiation and termination of the auto scroll by operating the operational section  13 . 
     During execution of the auto scroll, a caption line currently in reproduction is displayed in the center of the caption list. In the example of the screen D 1  shown in  FIG. 33 , a currently reproduced caption line (caption line “Good morning” displayed in the caption area MA) is arranged in the center of the list area LA for displaying the caption list. The reason why the currently reproduced caption line is arranged in the center of the list area LA is that better visibility is provided near the center of the list area LA. 
     During playback of a content, according to a caption playback timing TMn stored in the caption management data  122 , the cell phone  1  plays back the caption line corresponding to the caption playback timing TMn. The caption management data  122  is generated by the process in  FIG. 6 . 
     Next, the operation of the auto scroll which is one feature of the embodiment will be described. When the user instructs the initiation of the auto scroll, the control unit  11  initiates the process shown in  FIG. 34 , and sets “ON” an auto scroll flag indicating whether or not to execute auto scroll (step S 221 ). Further, the control unit  11  causes the display unit  14  to display the caption list on the display panel  5 . In the example of  FIG. 33 , the screen D 1  where the caption list is shown in the list area LA is displayed. 
     In this state, the user can select a caption line to start being played from caption lines in the caption list. When the user selects a caption line, the process goes to step S 222  to extract a video image having the playback timing (PTS unit) corresponding to the caption playback timing TMn. 
     The control unit  11  extracts information on a video frame from a video PES (step S 222 ), and returns the process to step S 222  when the video frame is not an IDR frame (step S 223 ; No). 
     When the video frame is an IDR frame (step S 223 ; Yes), on the other hand, the control unit  11  acquires an elapse time from the beginning of the playback of the top video frame to the playback of the IDR frame (step S 224 ). The elapse time is a difference obtained by subtracting the playback timing (PTS unit) of the top video image in the content-recorded data  121  from the playback timing (PTS unit) of the IDR frame. 
     Subsequently, the control unit  11  determines whether the extracted IDR frame may correspond to the caption line Mn currently in reproduction. For this purpose, the control unit  11  determines whether the caption playback timing TMn of the caption line Mn is greater than the currently acquired elapse time (step S 225 ). 
     When the caption playback timing TMn is greater than the currently acquired elapse time (step S 225 ; Yes), the extracted IDR frame is played back before the caption line Mn and can correspond to the caption line Mn. At this time, the control unit  11  saves the position of the data of the IDR frame (step S 226 ), and returns the process to step S 222 . The position of data to be saved in step S 226  is, for example, the display time of the IDR frame, the number of the video PES to store the IDR frame, an address in the storage unit  12  where the IDR frame is stored, or the like. 
     When the caption playback timing TMn is smaller than the currently acquired elapse time (step S 225 ; No), the previously extracted IDR frame is played back directly before the currently played caption line Mn. The control unit  11  therefore reads a video frame from the video position stored in step S 226  and displays the video frame on the display panel  5  (step S 227 ). 
     The control unit  11  displays a caption line corresponding to the displayed video image in the caption area MA (step S 228 ). Further, the control unit  11  displays the caption list in the list area (step S 229 ). At this time, the caption line currently played is arranged near the center of the list area LA. 
     The control unit  11  determines whether there is an instruction from the user to terminate the auto scroll. Accordingly, the control unit  11  determines whether the auto scroll flag is “ON”, and terminates the process when the flag is “OFF” (step S 2210 ; No). 
     When the auto scroll flag is “ON” (step S 2210 ; Yes), on the other hand, the control unit  11  activates the timer (not shown) to detect the elapsing of a “caption changeover time” stored in the storage unit  12 . 
     Upon detection of the elapsing of the “caption changeover time” (step S 2211 ; Yes), to play back a caption line to be played next, the control unit  11  acquires the caption line and a caption display time associated therewith (step S 2212 ). Then, the process returns to step S 222 . This is the end of the process of automatically scrolling each caption line every time a predetermined “caption changeover time” elapses. 
     Application Example 3-1 
     In the third embodiment, each caption line displayed in the caption list is changed every time the caption changeover time, which is set to the same value regardless of the number of characters in the caption line, elapses. When a caption line contains a large number of characters, therefore, it is likely that before the user finishes reading the caption line, a next caption line is displayed. When the number of characters is small, there is a standby time to the display of a next caption line after the user finishes reading the caption line. 
     To avoid this problem, the “caption changeover time” should be changed according to the number of characters in a caption line. The following will describe a cell phone  1  according to an application example 3-1 which executes such an auto scroll. 
     The fundamental configuration of the cell phone  1  according to the application example 3-1 is the same as the configuration shown in  FIG. 2 , except that the storage unit  12  stores caption management data  122   a  in place of the caption management data  122  shown in  FIG. 4 . The caption management data  122   a  associates the caption playback timing TMn, the caption line Mn and the number of characters KZn in the caption line with one another. 
     The process of generating the caption management data  122   a  is basically the same as the one exemplified in  FIG. 6 . In the application example 3-1, as shown in  FIG. 36A , the control unit  11  executes substantially the same process as that of step S 17  shown in  FIG. 6  (step S 17   a ), then counts the number of characters contained in the caption line (step S 17   b ), and stores the number in the caption management data  122   a.    
     The auto scroll process in the application example 3-1 is basically the same as the one exemplified in  FIG. 34 , except that the control unit  11  executes a process illustrated in  FIG. 36B  instead of the process of step S 2210  shown in  FIG. 34 . That is, when determining that the auto scroll flag is “ON” (step V 11 ; Yes), the control unit  11  acquires the number of characters KZn in the caption line Mn currently in reproduction from the caption management data  122   a  (step V 12 ). 
     Subsequently, based on the acquired number of characters KZn, the control unit  11  acquires the “caption changeover time” according to the number of characters KZn (step V 13 ). For example, the control unit  11  acquires the “caption changeover time” by multiplying the number of characters KZn by a prescribed display time t per character. When the display time t is 0.2 second, for example, the “caption changeover time” corresponding to a caption line containing 10 characters is 2 seconds and the “caption changeover time” for a caption line containing 20 characters is 4 seconds. 
     Then, the process returns to the process in  FIG. 34 , and upon detection of the elapse of the “caption changeover time” with the timer (step S 2211 ; Yes), the control unit  11  acquires a next caption line (step S 2212 ), and displays the caption line by the scroll process. 
     Application Example 3-2 
     In the third embodiment, when the number of characters KZn in the caption line Mn is small, the user may not read the caption line depending on the value of the display time t per character. When the display time t is 0.2 second, for example, a next caption line is displayed after the “caption changeover time” (0.2 second) elapses after the display of a caption line whose character number KZn is “1”. 
     To overcome the problem, even in a case of displaying a caption line with fewer characters, the caption changeover time corresponding to the caption line should be set longer. 
     Accordingly, caption lines are grouped according to the number of characters in each caption line, and a “caption changeover time” suitable for reach a caption line corresponding to each group should be set group by group. For example, when the number of characters KZn is 1 to 10, the caption changeover time is set to 2 seconds, and when the number of characters KZn is 11 to 20, the caption changeover time is set to 3 seconds. The following will describe a cell phone  1  according to the application example 3-2 which executes such an auto scroll. 
     The fundamental configuration of the cell phone  1  according to the application example 3-2 is the same as the configuration shown in  FIG. 2 , except that the storage unit  12  shown in  FIG. 2  prestores display changeover time information  123  which associates a category KB provided according to the number of characters in a caption line, and a “caption changeover time TS” corresponding to the category KB with each other, as shown in  FIG. 37A . 
     The auto scroll process in the application example 3-2 is basically the same as the one exemplified in  FIG. 34 , except that the control unit  11  in the application example 3-2 executes processes of steps V 21  to V 23  shown in  FIG. 37B  in place of step S 2210  shown in  FIG. 34 . 
     That is, in the application example 3-2, substantially the same process as steps S 221  to S 229  shown in  FIG. 34  is executed to display a captioned video image and a caption list. 
     Subsequently, when determining that the auto scroll flag is “ON” (step V 21 ; Yes), the control unit  11  acquires the number of characters in the caption line (step V 22 ). Further, referring to the display changeover time information  123 , the control unit  11  reads the “caption changeover time TS” associated with the group to which the number of characters belongs (step V 23 ). 
     Then, the process returns to the process in  FIG. 34 , and the control unit  11  acquires a next caption line (step S 2212 ) after the “caption changeover time” elapses (step S 2211 ; Yes), then performs the auto scroll. This is the end of the process of automatically scrolling caption lines according to the “caption changeover time” corresponding to each group provided according to the number of characters in a caption line. 
     In general, the time to read a caption line differs user by user. From the viewpoint of improving the user&#39;s convenience, it is desirable that each user can edit the “caption changeover time” set in each of the foregoing third embodiment and the application examples 3-1 and 3-2. An editing function of the cell phone  1  will be described below. 
     According to the third embodiment and the application examples 3-1 and 3-2, during auto scroll, a screen D 21  showing a captioned video image together with a caption list is displayed as exemplified in  FIG. 38A . In this state, when the user depresses a soft key E 1  (“sub menu”) using the operational section  13 , the control unit  11  displays a sub menu screen. In the example of  FIG. 38B , a sub menu screen is the screen D 22 . 
     When the user selects “1. set auto scroll time” in available selections in the sub menu and presses a “Select” key, a screen for setting the time for auto scroll corresponding to the third embodiment and the application examples 3-1 and 3-2 is displayed. The following will describe the operation of setting the “caption changeover time” in the third embodiment and the application examples 3-1 and 3-2 using each time setting screen. 
     In the setting of the “caption changeover time” according to the third embodiment, the user directly changes the value of the “caption changeover time” to a value desired by the user. In the example of  FIG. 38C , the user changes the value to be set for the “caption changeover time” (value shown in text box E 2 ) using the cursor key  3  or the like to select the desired value (e.g., 3 seconds). 
     When the user depresses a “Set” key while the desired value is displayed, the control unit  11  stores the value as the “caption changeover time” in the storage unit  12 . The value to be set for the “caption changeover time” may be directly input by the user. 
     In the setting of the “caption changeover time” according to the application example 3-1, the “caption changeover time” of each caption line is acquired from the product of the display time t per character and the number of characters KZn in each caption line. The display time t per character is the only parameter the user can edit to change the “caption changeover time”. 
     For this purpose, a screen D 24  which allows the value to be set for the display time t (value in text box E 3 ) to be edited is displayed as exemplified in  FIG. 38D . The value to be set for the display time t may be directly input by the user or may be selected by the user changing a preset value with the cursor key  3 . 
     As shown in  FIG. 38E , a total caption playback time needed to play back all the caption lines in a content (shown in a text box E 4 ), an expected time of completion to view the content to the end (shown in a text box E 5 ), etc. may be displayed at the same time. This provides some guide point to decide the display time per character, thus improving the convenience. 
     To achieve the purpose, the total number of characters in the entire caption lines included in a captioned video image (hereinafter “number of entire-captions characters KZt”) is acquired beforehand. The control unit  11  adds up the numbers of characters KZ 1  to KZN in the caption management data  122   a  shown in  FIG. 35 , and stores the resultant number of entire-captions characters KZt in the storage unit  12 . 
     In the example shown in  FIG. 38E , when the user input “0.3 second” as the value for the display time t per character, the display time t (0.3 second)×the number of entire-captions characters KZt is displayed in the text box E 4 . Further, the expected time of completion obtained by adding the time shown in the text box E 4  to the present time is displayed in the text box E 5 . 
     The total caption playback time (value in the text box E 4 ) may be set editable by the user. In that case, the display time per character when auto scroll is carried out according to the value edited by the user is displayed in the text box E 3 . The display time is acquired by dividing the total caption playback time, edited by the user, by the number of entire-captions characters KZt. The text box E 5  shows a time obtained by adding the total caption playback time edited by the user to the present time. 
     The expected time of completion may be set editable by the user. In that case, the total caption playback time obtained from the difference between the value (expected time of completion) edited by the user and the present time is displayed in the text box E 4 , and the display time t per character then is displayed in the text box E 3 . 
     In the setting of the “caption changeover time” according to the application example 3-2, the “caption changeover time TS” corresponding to each group provided according to the number of characters in a caption line is editable. The value to be set for the “caption changeover time TS” may be directly input by the user or selected from present values. 
     In the example of  FIG. 38F , when the user depresses the “Set” key during display of a desired value, the value is set as the “caption changeover time” in the display changeover time information  123  shown in  FIG. 37A . At this time, the “caption changeover time” corresponding to a caption line which contains 1 to 10 characters is set to 3 seconds, and the “caption changeover time” corresponding to a caption line which contains 11 to 20 characters is set to 6 seconds. 
     Application Example 3-3 
     In the third embodiment and the application examples 3-1 and 3-2, the user cannot grasp when the display of the caption line the user is currently reading is changed to the display of a next caption line. In this case, it is difficult for the user to adjust the speed of reading a caption line according to the timing of switching the display of the caption line. 
     To avoid the problem, the time remaining to the switching of the display of a caption line from the current point of time should be displayed. The following will describe a cell phone  1  according to an application example 3-3 which displays such a remaining time. 
     In the application example 3-3, the time remaining until a current caption line is changed to a next caption line is acquired. For example, the remaining time is the difference between the “caption changeover time” and the time measured by the timer. During execution of auto scroll, the remaining time is displayed on the display panel  5 . 
     The mode for showing the remaining time is optional. When the remaining time is shown by text, for example, the remaining time may be given by a message informing the user of the remaining time (e.g., “2 seconds to the next caption line”) or the like. 
     When the remaining time is shown by an icon, the remaining time may be given by an icon representing an analog clock. In this case, when the remaining time indicated by the icon becomes zero, the caption display may be switched to a next caption line. 
     Further, the color of a caption line which is being played back may be changed according to the passing of the time measured by the timer. For example, a caption line may be displayed in blue at the beginning of the playback of the caption line, and may be displayed in red before it is changed over to a next caption line. 
     When the display of a caption line is switched, the control unit  11  may inform the user of that event by outputting an alarm or by vibration. This allows the user to recognize that the caption line has been changed, thus improving the user&#39;s convenience. 
     Application Example 3-4 
     In the embodiment, with regard to a video image being displayed, the user cannot know the timing of playing back a video image during recording of a content. 
     An application example 3-4 is designed to display the display time of a video image currently in reproduction in the total playback time in the content-recorded data  121  (hereinafter “total playback time TT”), thereby improving the user&#39;s convenience. 
     The auto scroll process of the application example 3-4 is basically the same as the one shown in  FIG. 34 , except that in the application example 3-4, the control unit  11  executes the process of step S 229  in  FIG. 34 , and then executes processes of steps V 31  to V 34  shown in  FIG. 40  before executing the process of step S 2210 . 
     Specifically, after displaying a captioned video image and a caption list (steps S 221  to S 229  in  FIG. 34 ), the control unit  11  acquires the total playback time TT relating to the content-recorded data  121  which is currently displayed (step V 31 ). The total playback time TT can be acquired by, for example, associating the total playback time TT with the content-recorded data  121  as an attribute of a file storing a recorded content, beforehand. 
     Subsequently, the elapse time of the video image currently displayed, which is stored in step S 226  in  FIG. 34  (step V 32 ), the elapse time is divided by the total playback time TT to acquire a ratio of the elapse time to the total playback time (hereinafter “progress rate”) (step V 33 ). Further, an image indicating the progress rate is displayed on the display panel  5  (step V 34 ). 
     The mode for showing the progress rate is optional, and may be shown by an image or by text. As one example of image-based display, a total bar B 1  (e.g., horizontal bar) representing the total playback time and a ratio bar B 2  indicating the progress rate are displayed one above the other. For example, when the size of the total bar B 1  is set to 200 pixels, the size of the ratio bar B 2  is 200 pixels×10%=20 pixels when the progress rate is 10%. 
     In the example of  FIG. 39A , as a top caption line (caption display time “00:00:00”) and a video image corresponding to the caption line are being displayed, the progress rate RT is 0. At this time, only the total bar B 1  is displayed. 
     In the example of  FIG. 39B , a second caption line from the top in the caption management data  122  shown in  FIG. 4  is being displayed. At this time, the ratio bar B 2  indicating the progress rate which is determined based on the display time of the video image (00:00:09) is displayed above (on) the total bar B 1 . 
     In the example of the display method in  FIG. 39B , the user can grasp the progress rate at a present time, but cannot obtain information on the time represented by the unit of hour, minute and second or the like. 
     To avoid the problem, as exemplified in  FIG. 39C , the total playback time TT corresponding to the total bar B 1 , the display time of a video image currently in reproduction which corresponds to the ratio bar B 2 , etc. may be displayed. This allows the use to obtain information on the time needed to play back the remaining portion of the currently viewed content, and the playback time of the content viewing of which has been completed currently, thus further improving the convenience. 
     As exemplified in  FIG. 39D , the progress rate of each caption line may be displayed at a corresponding position in the total bar B 1  with an image PI indicating the presence of each caption line. Accordingly, the user can grasp that a caption line is displayed when the end of the ratio bar B 2  reaches the image PI according to the execution of auto scroll. 
     In addition, a caption-less part in a recorded program can be grasped at a glance. When a recorded program is a drama, for example, there are no captions in scenes during the opening theme, or ending theme or during commercial. When there is a user who wants to view just the opening, however, it is apparent that a caption-less part near the top of the program is the opening part, so that the user can view the opening by playing back the program without fast forwarding that part. 
     In the modification shown in  FIG. 39D , the progress rate RTn is acquired for each caption line Mn, and caption management data  122   b  having each progress rate associated with each caption line is stored in the storage unit  12 . In the example of the caption management data  122   b  shown in  FIG. 41 , because the caption playback time t 1  of the top caption line M 1  is 00:00:00, the progress rate RT 1  is “0”. The progress rate may be acquired beforehand before playing back a content or may be acquired during playback of a content and temporarily stored in the storage unit  12 . 
     When auto scroll is executed in the modification, each progress rate RTn is acquired from the caption management data  122   b  and the image PI is displayed at a position on the total bar B 1  which corresponds to each progress rate in step V 34  shown in  FIG. 40 . It is desirable that the image PI should be displayed in a color different from the color of each bar so that it can be distinguished even if the total bar B 1  and the ratio bar B 2  are displayed overlying each other. 
     Application Example 3-5 
     In the embodiment, when the user selects a top caption line in the content-recorded data  121  from the caption list, playback starts from the top caption line and a video image having a playback timing associated with the caption line. 
     Even when a content contains a video frame which is played back before an IDR frame corresponding to the top caption line is played back, such a video frame is not reproduced. When the top caption line is displayed three minutes after the playback of the content has started, video images are not played back until then. 
     The problem can be overcome by associating a pseudo caption line (hereinafter “temporary caption line”) with the playback timing of the top video frame and playing back the content starting from the temporary caption line. The following will describe a cell phone  1  according to an application example 3-5 which executes such an operation. 
     The fundamental configuration of the cell phone  1  according to the application example 3-5 is the same as the configuration shown in  FIG. 2 , except that the storage unit  12  stores caption management data  122   c  shown in  FIG. 42  instead of the caption management data  122  shown in  FIG. 4 . A caption line in the caption management data  122   c  additionally includes a temporary caption line which is not included in the content-recorded data  121 , in addition to the caption lines Mn extracted from the content-recorded data  121 . 
     In  FIG. 42 , “(top of program)” is newly added and a caption line indicating the content is a temporary caption line KM. A caption display time TMn is set to “00:00:00” so that this temporary caption line KM is associated with the top IDR frame in the content-recorded data  121 . The storage of the temporary caption line in the caption management data  122   c  should be carried out at the time as a caption line Mn is extracted from the caption PES. 
     Further, the temporary caption line may be added during execution of an application for playing back a content when caption management data  122  shown in  FIG. 4  is mapped in the work memory to display the caption line Mn. 
     A process for displaying a top video image in a content without changing the content of the caption management data  122  will be described below. When the user instructs execution of an application for viewing a content, as shown in  FIG. 44 , the control unit  11  determines whether the top caption line corresponds to the top video frame (step V 41 ). 
     At this time, the control unit  11  refers to the caption management data  122  to determine whether the caption display time of the top caption line is “00:00:00”, and when it is “00:00:00” (step V 41 ; Yes), the process goes to step V 45 . The normal video display process in step V 45  is substantially the same as processes in steps S 222  to S 229  shown in  FIG. 34 . 
     When the caption display time of the top caption line is not “00:00:00” (step V 41 ; No), the IDR frame at the top of the content-recorded data  121  is displayed (step V 42 ). Further, the temporary caption line KM corresponding to the IDR frame is displayed in the caption area MA (step V 43 ), and a caption list where the temporary caption line KM currently displayed is positioned in the center is displayed in the list area LA (step V 44 ). The processes of steps V 42  to V 44  causes a screen D 42  exemplified in  FIG. 43B  to be displayed. 
     In the application example 3-5, as shown in  FIG. 45 , when the user instructs to display a caption line preceding the caption line currently displayed by one in place of the currently displayed caption line, it is determined whether the currently displayed caption line is the top one. This instruction can be given as the user depresses the cursor key  3  upward or so. 
     When the currently displayed caption line is not the top caption line (step V 51 ; No), the process goes to step V 55 . The process of step V 55  is substantially the same as the processes of steps S 222  to S 229  shown in  FIG. 34 . 
     When the currently displayed caption line is the top caption line (step V 51 ; Yes), on the other hand, the processes of steps V 52  to V 54  are performed. The processes of steps V 52  to V 54  are substantially the same as the processes of steps V 42  to V 44  shown in  FIG. 44 . 
     The association of a temporary caption line with a video image is not limited to a case where the top caption line is not associated with the top video image. The association is likewise applicable to a case where the last caption line in a content is not associated with the last video image. When the last caption line in a content is not associated with the last video image, the last video image is not displayed, so that the screen D 43  exemplified in  FIG. 43C  is displayed. When a temporary caption line is associated with the last video image and is displayed, a screen D 44  exemplified in  FIG. 43D  is displayed. 
     According to the third embodiment, as explained above, every time a predetermined “caption changeover time” elapses, a next caption line is played back instead of the caption line currently in reproduction, and the caption list is automatically scrolled. Accordingly, the user does not need to display a caption line by operating the cursor key  3  or the like, thus improving the user&#39;s convenience. 
     According to the application example 3-1, the caption list is automatically scrolled according to the “caption changeover time” which is obtained by multiplying the “display time t per character” by the number of characters KZn in a caption line. Accordingly, as the number of characters in a caption line becomes greater, the time for displaying the caption line becomes longer, thus improving the user&#39;s convenience. 
     According to the application example 3-2, a caption line is grouped according to the number of characters, and the caption list is automatically scrolled according to the “caption changeover time” corresponding to the grouping. Even when there is a small number of characters in a caption line currently displayed, the caption line is displayed according to the same “caption changeover time” as set for a caption line which contains the largest number of characters in the group, making the time for the user to read the caption line. 
     According to the embodiments of the present invention, the “caption changeover time” can be edited by the user. Accordingly, the user can change the display of a caption line according to the user&#39;s preference. 
     In the application example 3-3, the time remaining until the caption display is changed to the display of a next caption line is displayed on the display panel  5 . This can allow the user to adjust the speed of reading a caption line according to the timing of changing from the display of the caption line currently displayed to the display of a next caption line. 
     According to the application example 3-4, during playback of a content, the degree of completion of playback of the content up to the current point to the total playback time of the content-recorded data  121  is given to the user. With the displayed information, therefore, user can determine whether or not to continue viewing a content. 
     Further, the total playback time, the display time of a video image currently displayed, etc. are displayed. This can allow the user to grasp the time needed to complete the playback of an unplayed part of the content currently viewed, the viewing time from the beginning of the playback of the content to the present time, and so forth. 
     According to the application example 3-5, when the top caption line in a content is not associated with the top video image, a temporary caption line KM is associated with the playback timing of the top video image. Then, playback of caption lines is started from the temporary caption line KM. This permits the user to view the top video image, thus leading to an improvement on the user&#39;s convenience. 
     The ON/OFF of the display of a caption list may be set editable by the user. In this case, auto scroll should be started when a caption line is selected from the caption list after the display of the caption list is enabled from the disabled state. 
     According to the application example 3-5, the content of the temporary caption line is not limited to a sequence of characters of “(top of program)”, and may be another sequence of characters or blank. A video image to be associated with a temporary caption line is not limited to the top video image in a content, and may be any video image as long as it is played before a video image corresponding to the caption display time of the top caption line. For example, the temporary caption line may be the IDR frame of the top of a program or a P frame near the IDR frame. 
     The conception of the present invention is not limited to a dedicated computer system, and may be adaptable to any portable electronic device having a contents recording/reproducing function, such as a PDA, electronic camera, electronic wrist watch, portable TV or car navigation system. That is, a computer program which permits a computer to function and operate as the cell phone  1  may be created, distributed, lent, or installed in a computer so that the computer may be used as the cell phone  1 , or transferred or lent to someone or some entity. 
     Various embodiments and changes may be made thereunto without departing from the broad spirit and scope of the invention. The above-described embodiments are intended to illustrate the present invention, not to limit the scope of the present invention. The scope of the present invention is shown by the attached claims rather than the embodiments. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention.