Abstract:
The present invention relates to a video display apparatus and an operating method therefor. The operating method for a video display apparatus according to one embodiment of the present invention comprises: receiving video information on an incoming video from outside or on a broadcast video; detecting conversion information between a 2D video and a 3D video within 3D video information, when the received video information is 3D video information; performing a 2D signal processing or a 3D signal processing on either the incoming video from outside or the broadcast video, according to the conversion information. In this way, it becomes easier to find out whether an incoming video from an external device is a 2D video or a 3D video.

Description:
This application is the National Phase of PCT/KR2010/002583 filed on Apr. 23, 2010, which claims priority under 35 U.S.C. 119(e) of U.S. Provisional application No. 61/172,225 filed on Apr. 24, 2009, all of which are hereby expressly incorporated by reference into the present application. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a video display apparatus and a method of operating the same and, more specifically, to a video display apparatus or a video display method, which are capable of easily checking whether a video received from an external device is a 2D video or a 3D video. 
     BACKGROUND ART 
     A video display apparatus is an apparatus equipped with a function of displaying a video which can be watched by a user. A user can watch broadcasting through a video display apparatus. The video display apparatus displays broadcasting selected by a user, from broadcast signals transmitted by a broadcasting station, in a display. There is a tendency that broadcasting is now being switched from analog broadcasting to digital broadcasting worldwide. 
     Digital broadcasting refers to broadcasting that transmits digital videos and audio signals. Digital broadcasting has less data loss because it is resistant to external noise, has advantageous error correction, and provides a vivid screen, as compared with analog broadcasting. Furthermore, digital broadcasting, unlike analog broadcasting, enables bi-directional service. 
     Furthermore, there are various researches recently being carried out on a stereoscopic image. Stereoscopic image technology gradually becomes general and commercialized not only in computer graphics, but also in other various environments and techniques. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     An object of the present invention is to provide a video display apparatus and a method of operating the same, which are capable of easily checking whether an image or a broadcast video received from an external device is a 2D video or a 3D video. 
     Furthermore, another object of the present invention is to provide a video display apparatus and a method of operating the same, in which a user can easily check conversion between a 3D video and a 2D video at the time of the conversion. 
     Technical Solution 
     To achieve the objects, a method of operating a video display apparatus according to an embodiment of the present invention comprising the steps of receiving video information about a received external video or a received broadcast video, detecting conversion information between a 2D video and a 3D video within 3D video information, if the received video information is the 3D video information, and performing 2D signal processing or 3D signal processing on the received external video or the received broadcast video based on the conversion information. 
     Furthermore, to achieve the objects, a video display apparatus according to an embodiment of the present invention comprises an external device interface unit for transmitting and receiving data to or from an external device, a control unit for detecting conversion information between a 2D video and a 3D video from among pieces of video information about a received broadcast video or an external video received from the external device and for performing 2D signal processing or 3D signal processing on the received external video or the received broadcast video based on the conversion information, and a display for displaying a video subjected to the 2D signal processing or the 3D signal processing. 
     Advantageous Effects 
     According to an embodiment of the present invention, if video information about an external input image or a broadcast video is received and the received video information is 3D video information, whether the image or the broadcast video received from an external device is a 2D video or a 3D video can be easily checked by detecting conversion information between the 2D video and the 3D video within the 3D video information. 
     Furthermore, an object indicating conversion between a 3D video and a 2D video is displayed at the time of the conversion, so that a user can easily check the conversion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an internal block diagram of a video display apparatus according to an embodiment of the present invention; 
         FIG. 2  is an internal block diagram of a control unit of  FIG. 1 ; 
         FIG. 3  is an internal block diagram of a video decoder of  FIG. 2 ; 
         FIG. 4  is a diagram showing various formats of a 3D video; 
         FIG. 5  is a diagram showing the operation of a shutter glasses according to a frame sequential format of  FIG. 4 ; 
         FIG. 6  is a diagram illustrating that an image is formed by a left-eye image and a right-eye image; 
         FIG. 7  is a diagram illustrating the depth of a 3D video according to the interval between a left-eye image and a right-eye image; 
         FIG. 8  is a flowchart illustrating a method of operating the video display apparatus according to an embodiment of the present invention; and 
         FIGS. 9 to 14  are diagrams to which reference is made to describe various examples of the method of operating the video display apparatus shown in  FIG. 8 . 
     
    
    
     BEST MODE FOR IMPLEMENTING THE INVENTION 
     The present invention is described in more detail with reference to the drawings. 
     The suffixes of constituent elements used in the following description, such as “module” and “unit,” are assigned by simply taking only the easiness of writing this specification into consideration, but are not particularly given importance and roles. Accordingly, the “module” and “unit” may be mixed in use. 
       FIG. 1  is an internal block diagram of a video display apparatus according to an embodiment of the present invention. 
     Referring to  FIG. 1 , the video display apparatus  100  according to the embodiment of the present invention may include a tuber  110 , a demodulation unit  120 , an external device interface unit  130 , a network interface unit  135 , a storage unit  140 , a user input interface unit  150 , a control unit  170 , a display  180 , an audio output unit  185 , and an additional 3D display  195 . 
     The tuber  110  selects Radio Frequency (RF) broadcast signals corresponding to a channel, selected by a user, or to all previously stored channels, from among RF broadcast signals received through an antenna. Furthermore, the tuber converts the selected RF broadcast signals into intermediate frequency signals or a baseband video, or audio signals. 
     For example, if the selected RF broadcast signal is a digital broadcast signal, the tuber converts the selected RF broadcast signal into a digital IF signal DIF. If the selected RF broadcast signal is an analog broadcast signal, the tuner converts the selected RF broadcast signal into an analog baseband video or an audio signal CVBS/SIF. That is, the tuber  110  may process a digital broadcast signal or an analog broadcast signal. The analog baseband video or the audio signal CVBS/SIF outputted from the tuber  110  may be directly inputted to the control unit  170 . 
     Furthermore, the tuber  110  may receive an RF broadcast signal of a single carrier according to the Advanced Television System Committee (ATSC) method or an RF broadcast signal of plural carriers according to the Digital Video Broadcasting (DVB) method. 
     Meanwhile, in the present invention, the tuber  110  may sequentially select the RF broadcast signals of all the broadcast channels stored by a channel memory function, from among the RF broadcast signals received through the antenna, and may convert the selected RF broadcast signals into intermediate frequency signals or a baseband video, or audio signals. 
     The demodulation unit  120  receives the digital IF signal DIF converted by the tuber  110  and performs a demodulation operation. 
     For example, if the digital IF signal outputted from the tuber  110  is an ATSC method, the demodulation unit  120  performs 8-Vestigal Side Band (8-VSB) demodulation. Furthermore, the demodulation unit  120  may perform channel decoding. To this end, the demodulation unit  120  may include a Trellis decoder, an de-interleaver, a Reed Solomon decoder, etc. and perform Trellis decoding, de-interleaving, and Reed Solomon decoding. 
     For example, if the digital IF signal outputted from the tuber  110  is a DVB method, the demodulation unit  120  performs Coded Orthogonal Frequency Division Modulation (COFDMA) demodulation. Furthermore, the demodulation unit  120  may perform channel decoding. To this end, the demodulation unit  120  may include a convolution decoder, a de-interleaver, a Reed-Solomon decoder, etc. and perform convolution decoding, de-interleaving, and Reed Solomon decoding. 
     The demodulation unit  120  may output a stream signal TS after performing demodulation and channel decoding. Here, the stream signal may be a multiplexed signal of a video signal, an audio signal or a data signal. For example, the stream signal may be an MPEG-2 Transport Stream (TS) in which a video signal according to the MPEG-2 standard, an audio signal according to Dolby AC-3 standard, etc. are multiplexed. More particularly, the MPEG-2 TS may include a header of 4 bytes and a payload of 184 bytes. 
     Meanwhile, the demodulation unit  120  may be separately provided according to the ATSC method and the DVB method. That is, an ATSC demodulation unit and a DVB demodulation unit may be separately provided. 
     The stream signal outputted from the demodulation unit  120  may be inputted to the control unit  170 . The control unit  170  performs demultiplexing, video/audio signal processing, etc., outputs a video to the display  180 , and outputs audio to the audio output unit  185 . 
     The external device interface unit  130  may transmit data to or receive data from an external device  190  connected thereto. To this end, the external device interface unit  130  may include an A/V input/output unit (not shown) or a wireless communication unit (not shown). 
     The external device interface unit  130  may be coupled to the external device  190 , such as a Digital Versatile Disk (DVD), blue-ray, a game player, a camera, a camcorder, and a computer (notebook), in a wired/wireless manner. The external device interface unit  130  transfers a video, audio, or data signals, externally received through the external device  190  connected thereto, to the control unit  170  of the video display apparatus  100 . Furthermore, the external device interface unit  130  may output a video, audio or data signals, processed by the control unit  170 , to an external device connected thereto. To this end, the external device interface unit  130  may include an A/V input/output unit (not shown) or a wireless communication unit (not shown). 
     The A/V input/output unit may include a USB terminal, a Composite Video Banking Sync (CVBS) terminal, a component terminal, an S-video terminal (analog), a Digital Visual Interface (DVI) terminal, a High Definition Multimedia Interface (HDMI) terminal, an RGB terminal, a D-SUB terminal, etc. so that the video and audio signals of the external device can be inputted to the video display apparatus  100 . 
     The wireless communication unit may perform near field wireless communication with another electronic device. The video display apparatus  100  may be coupled to another electronic device over a network according to communication standards, such as bluetooth, Radio Frequency Identification (RFID), Infrared Data Association (IrDA) communication, Ultra Wideband (UWB), zigbee, and Digital Living Network Alliance (DLNA). 
     The external device interface unit  130  may also be coupled to various settop boxes through at least one of the above various terminals, and it may perform input/output operations with the settop boxes. 
     Meanwhile, the external device interface unit  130  may transmit data to and receive data from the additional 3D display  195 . 
     The network interface unit  135  provides an interface for connecting the video display apparatus  100  to wired/wireless networks including an Internet network. The network interface unit  135  may include an Ethernet terminal for a connection with the wired network and may employ a Wireless LAN (WLAN, Wi-Fi), Wireless broadband (Wibro), World Interoperability for Microwave Access (Wimax), and a High Speed Downlink Packet Access (HSPDA) communication standard for a connection with the wireless network. 
     The network interface unit  135  may receive content or data, provided by the Internet, a content provider, or a network operator, over a network. That is, the network interface unit  135  may receive content, such as movies, advertising, games, VOD, and broadcast signals provided by the Internet and the content provider over a network, and relevant information. Furthermore, the network interface unit  135  may receive update information and update files for firmware which are provided by the network operator. Furthermore, the network interface unit  135  may transmit data to the Internet, the content provider, or the network operator. 
     The network interface unit  135  may also be coupled to, for example, Internet Protocol (IP) TV and configured to receive videos, audio, or data signals processed by a settop box for IPTV and transfer them to the control unit  170  so that bi-directional communication is possible. The network interface unit  135  may transfer signals, processed by the control unit  170 , to the settop box for IPTV. 
     Meanwhile, the above IPTV may mean ADSL-TV, VDSL-TV, FTTH-TV, etc. according to a type of a transfer network or may mean TV over DSL, Video over DSL, TV overIP (TVIP), Broadband TV (BTV), etc. Furthermore, the IPTV may mean Internet TV that can access the Internet or full-browsing TV. 
     The storage unit  140  may store a program for processing and controlling signals within the control unit  170  and may store videos subjected to signal processing, audio, or data signals. 
     The storage unit  140  may also perform a function of temporarily storing videos, audio, or data signals which are inputted to the external device interface unit  130 . Furthermore, the storage unit  140  may store information about a specific broadcast channel through the channel memory function, such as a channel map. 
     The storage unit  140  may include at least one type of storage media, such as a flash memory type, a hard disk type, a multimedia card micro type, card type memory (for example, SD or XD memory), RAM, and ROM (EEPROM, etc.). The video display apparatus  100  may play a file (a moving image file, a static image file, a music file, a document file, etc.) stored in the storage unit  140  and provide it to a user. 
     An embodiment in which the storage unit  140  is provided separately from the control unit  170  is shown in  FIG. 1 , but the scope of the present invention is not limited thereto. The storage unit  140  may be included in the control unit  170 . 
     The user input interface unit  150  transfers a signal, inputted by a user, to the control unit  170  or transfers a signal from the control unit  170  to a user. 
     For example, the user input interface unit  150  may receive user input signals, such as power on/off, channel selection, and screen setting, from a remote control apparatus  200  and transmit signals from the control unit  170  to the remote control apparatus  200  according to various communication methods, such as a Radio Frequency (RF) communication method and an IR communication method. 
     For example, the user input interface unit  150  may also transfer user input signals, inputted through local keys (not shown), such as a power key, a channel key, a volume key, and a setting key, to the control unit  170 . 
     For example, the user input interface unit  150  may also transfer user input signals, received from a sensing unit (not shown) for sensing a user&#39;s gesture, to the control unit  170  or may transmit signals from the control unit  170  to the sensing unit (not shown). Here, the sensing unit (not shown) may include a touch sensor, an audio sensor, a position sensor, an operation sensor, etc. 
     The control unit  170  may generate and output signals for video or audio output by demultiplexing received streams or processing demultiplexed signals through the tuber  110 , the demodulation unit  120 , or the external device interface unit  130 . 
     A video signal subjected to video processing in the control unit  170  may be inputted to the display  180  and displayed as a video corresponding to the video signal. Furthermore, the video signal subjected to video processing in the control unit  170  may be inputted to an external output device via the external device interface unit  130 . 
     An audio signal processed by the control unit  170  may be outputted to the audio output unit  185  in the form of sound. Furthermore, the audio signal processed by the control unit  170  may be inputted to an external output device via the external device interface unit  130 . 
     Although not shown in  FIG. 1 , the control unit  170  may include a demultiplexing unit, a video processing unit, etc., which is described later with reference to  FIG. 2 . 
     In addition, the control unit  170  may control the overall operation of the video display apparatus  100 . For example, the control unit  170  may control the tuber  110  so that RF broadcasting, corresponding to a channel selected by a user or to a previously stored channel, can be tuned. 
     The control unit  170  may also control the video display apparatus  100  in response to a user command, received through the user input interface unit  150 , or according to an internal program. 
     For example, the control unit  170  controls the tuber  110  so that the signal of a channel selected in response to a specific channel selection command received through the user input interface unit  150  is inputted. The control unit  170  also processes a video, audio, or data signals corresponding to the selected channel. The control unit  170  enables channel information, selected by a user, to be outputted through the display  180  or the audio output unit  185  along with a processed video or audio signals. 
     For another example, the control unit  170  enables a video signal or an audio signal, received from the external device  190  (for example, a camera or a camcorder) through the external device interface unit  130 , to be outputted through the display  180  or the audio output unit  185 , in response to an external device video play command received through the user input interface unit  150 . 
     Meanwhile, the control unit  170  may control the display  180  so that an image is displayed. For example, the control unit  170  may perform control so that broadcast video received through the tuber  110 , an external input video received through the external device interface unit  130 , a video received through the network interface unit  135 , or a video stored in the storage unit  140  is displayed in the display  180 . 
     Here, the video displayed in the display  180  may be a static image or a moving image and may be a 2D video or a 3D video. 
     Meanwhile, the control unit  170  generates a specific object, from among videos displayed in the display  180 , in the form of a 3D object and displays the specific object. For example, the object may be at least one of a connected web screen (newspaper, a magazine, etc.), an Electronic Program Guide (EPG), various menus, widgets, icons, static images, moving images, and text. 
     The 3D object may be processed to have a different depth from an image displayed in the display  180 . Preferably, the 3D object may be processed so that the 3D object looks like being projected as compared with the image displayed in the display  180 . 
     Meanwhile, the control unit  170  recognizes the position of a user on the bias of an image captured by a photographing unit (not shown). For example, the control unit  170  may check the distance (z-axis coordinates) between a user and the video display apparatus  100 . In addition, the control unit  170  may check x-axis coordinates and y-axis coordinates within the video display apparatus  100 , corresponding to a user position. 
     Meanwhile, although not shown, a channel browsing processing unit for generating a thumbnail video, corresponding to channel signals or external input signals, may be further included. The channel browsing processing unit may receive stream signals TS outputted from the demodulation unit  120 , stream signals outputted from the external device interface unit  130 , etc., extract images form the received stream signals, and generate a thumbnail video based on the extracted images. The generated thumbnail video may be inputted to the control unit  170  without change or may be coded and inputted to the control unit  170 . Furthermore, the generated thumbnail video may be coded in a stream form and then inputted to the control unit  170 . The control unit  170  may display a thumbnail list, including a plurality of the thumbnail videos, in the display  180  by using the received thumbnail videos. Here, the thumbnail list may be displayed according to an easy view method of displaying the thumbnail list in some regions in the state where a specific video has been displayed in the display  180  or may be displayed according to the whole view method of displaying the thumbnail list in most of the regions of the display  180 . 
     The display  180  generates a driving signal by converting a video signal, a data signal, an OSD signal, and a control signal processed by the control unit  170  or a video signal, a data signal, and a control signal received from the external device interface unit  130 . 
     The display  180  may be a PDP, an LCD, an OLED, a flexible display, or the like. In particular, according to an embodiment of the present invention, it is preferred that the display  180  be a three-dimensional (3D) display. 
     In order to watch a 3D video, the display  180  may be divided into an additional display method and an independent display method. 
     In the independent display method, the display  180  may independently implement a 3D video without an additional display (for example, glasses). Various methods, such as a lenticular method and parallax barriers, may be applied to the independent display method. 
     Meanwhile, in the additional display method, a 3D video is implemented by using an additional display other than the display  180 . Various method, such as a head mount, a display (HMD) type, and a glasses type, may be applied to the additional display method. Furthermore, the glasses type may be divided into a passive method, such as a polarization glasses type, and an active method, such as a shutter glasses type. Meanwhile, the head mount display type may also be divided into a passive method and an active method. 
     In an embodiment of the present invention, it is assumed that the additional 3D display  195  is provided in order to watch a 3D video. The additional 3D display  195  enables the additional display of the passive method or the additional display of the active method. It is hereinafter assumed that the additional 3D display  195  is the shutter glasses of the active method. 
     Meanwhile, the display  180  may be formed of a touch screen and used as an input device in addition to an output device. 
     The audio output unit  185  receives a signal (for example, a stereo signal, a 3.1 channel signal, or 5.1 a channel signal) subjected to audio processing in the control unit  170  and outputs the signal in the form of audio. The audio output unit  185  may be implemented using a speaker of various forms. 
     Meanwhile, the sensing unit (not shown), including at least one of a touch sensor, an audio sensor, a position sensor, and an operation sensor as described above in order to detect a user&#39;s gesture, may be further included in the video display apparatus  100 . A signal detected by the sensing unit (not shown) is transmitted to the control unit  170  via the user input interface unit  150 . 
     The control unit  170  may detect a user&#39;s gesture by detecting a video photographed by the photographing unit (not shown) or a signal detected by the sensing unit (not shown) or by combining the video and the signal. 
     The remote control apparatus  200  transmits a user input to the user input interface unit  150 . To this end, the remote control apparatus  200  may employ a method, such as bluetooth, RF communication, IR communication, UWB, and zigbee. Furthermore, the remote control apparatus  200  may receive videos, audio, or data signals outputted from the user input interface unit  150  and display them or output them in the form of audio. 
     The video display apparatus  100  may be a digital broadcast receiver as a fixed type, which is capable of receiving at least one of digital broadcasting of the ATSC method (7-VSB method), digital broadcasting of the DVB-T method (COFDM method), and digital broadcasting of the ISDB-T method (BST-OFDM method). Furthermore, the video display apparatus  100  may be a digital broadcast receiver as a movable type, which is capable of receiving at least one of digital broadcasting of the terrestrial DMB method, digital broadcasting of the satellite DMB method, digital broadcasting of the ATSC-M/H method, digital broadcasting of the DVB-H method (COFDM method), and digital broadcasting of the media forward link only method. Furthermore, the video display apparatus  100  may be a digital broadcast receiver for a cable, satellite communication, or IPTV. 
     Meanwhile, the video display apparatus described in this specification may include a TV receiver, a handheld phone, a smart phone, a notebook computer, a terminal for digital broadcasting, a Personal Digital Assistants (PDA), a Portable Multimedia Player (PMP), etc. 
     Meanwhile, the block diagram of the video display apparatus  100  shown in  FIG. 1  is a block diagram for an embodiment of the present invention. The constituent elements of the block diagram may be integrated, added, or omitted according to a specification of the video display apparatus  100  that is actually implemented. That is, 2 or more constituent elements of the video display apparatus  100  may be integrated into one element, or one constituent element of the video display apparatus  100  may be divided into 2 or more elements, if necessary. Furthermore, functions performed in each block are for illustrating an embodiment of the present invention, and a detailed operation or apparatus does not limit the scope of the present invention. 
       FIG. 2  is an internal block diagram of the control unit of  FIG. 1 ,  FIG. 3  is an internal block diagram of a video decoder of  FIG. 2 ,  FIG. 4  is a diagram showing various formats of a 3D video, and  FIG. 5  is a diagram showing the operation of a shutter glasses according to a frame sequential format of  FIG. 4 . 
     Referring to the drawings, the control unit  170  according to an embodiment of the present invention may include a demultiplexing unit  210 , a video processing unit  220 , an OSD generation unit  240 , a mixer  245 , a frame rate conversion unit  250 , and a formatter  260 . The control unit  170  may further include an audio processing unit (not shown) and a data processing unit (not shown). 
     The demultiplexing unit  210  demultiplexes received streams. For example, when MPEG-2 TSs are received, the demultiplexing unit  210  may separate the MPEG-2 TSs into a video, audio, and data signals by demultiplexing the MPEG-2 TSs. A stream signal inputted to the demultiplexing unit  210  may be a stream signal outputted from the tuber  110 , the demodulation unit  120 , or the external device interface unit  130 . 
     The video processing unit  220  may perform video processing on the demultiplexed video signal. To this end, the video processing unit  220  may include a video decoder  225  and a scaler  235 . 
     The video decoder  225  decodes the demultiplexed video signal, and the scaler  235  performs scaling so that the resolution of the decoded video signal can be outputted through the display  180 . 
     The video decoder  225  may include a decoder of various standards. 
       FIG. 3  illustrates a 3D video decoder  310  for decoding a 3D video signal within the video decoder  220 . 
     A demultiplexed video signal inputted to the 3D video decoder  310  may be, for example, a video signal coded according to the Multi-view Video Coding (MVC) standard, a video signal coded according to the dual AVC standard, or a signal in which a coded left-eye image signal and a coded right-eye image signal are mixed. 
     If the received signal is a signal in which a coded left-eye image signal and a coded right-eye image signal are mixed as described above, a 2D video decoder may be used without change. For example, if the demultiplexed video signal is a video signal coded according to the MPEG-2 standard or a video signal coded according to the AVC standard, the video signal may be decoded by an MPEG-2 decoder or an AVC decoder. 
     Meanwhile, the 3D video decoder  310  includes a basic view decoder  320  and an extended view decoder  330 . 
     For example, if an extended view video, from a coded 3D video signal inputted to the 3D video decoder  310 , has been coded according to the MVC standard, a relevant basic view video must be decoded in order to decode the extended view video. To this end, a basic view video decoded by the basic view decoder  320  is transferred to the extended view decoder  330 . 
     Accordingly, the decoded 3D video signal outputted from the 3D video decoder  310  has specific delay until the decoding of the extended view decoder  330  is completed. Consequently, the decoded basic view video and the decoded extended view video are mixed and outputted. 
     For example, if an extended view video, from a coded 3D video signal inputted to the 3D video decoder  310 , has been coded according to AVC, the extended view video and the basic view video can be decoded in parallel, unlike in the above MVC case. 
     Accordingly, the basic view decoder  320  and the extended view decoder  330  perform decoding operations independently. Meanwhile, the decoded basic view video and the decoded extended view video are mixed and outputted. 
     Meanwhile, the video signal decoded by the video processing unit  220  may include only a 2D video signal, a mixture of a 2D video signal and a 3D video signal, and only a 3D video signal. 
     For example, an external video signal received from the external device  190  or a broadcast video signal of a broadcast signal received from the tuber  110  may include only a 2D video signal, a mixture of a 2D video signal and a 3D video signal, and only a 3D video signal. Accordingly, the video signal is subsequently processed by the control unit  170 , in particular, the video processing unit  220 , so that a 2D video signal, a mixed signal of a 2D video signal and a 3D video signal, and a 3D video signal can be outputted. 
     In an embodiment of the invention, in particular, whether an external video signal received from the external device  190  or a broadcast video signal received from the tuber  110  is a 2D video signal or a 3D video signal can be easily checked. This is described later with reference to  FIG. 8  and subsequent drawings. 
     Meanwhile, the video signal decided by the video processing unit  220  may be a 3D video signal of various formats. For example, the video signal decided by the video processing unit  220  may be a 3D video signal consisting of a color image and a depth image, a 3D video signal consisting of a video signal having a plurality of view points. The video signal having a plurality of view points may include, for example, a left-eye image signal and a right-eye image signal. 
     Here, the formats of the 3D video signal, as shown in  FIG. 4 , may include a side-by-side format ( FIG. 4   a ) in which a left-eye image signal L and a right-eye image signal R are disposed left and right, a frame sequential format ( FIG. 4   b ) in which a left-eye image signal L and a right-eye image signal R are disposed in a time-dividing way, a top/down format ( FIG. 4   c ) in which a left-eye image signal L and a right-eye image signal R are disposed at the top and bottom, an interlaced format ( FIG. 4   d ) in which a left-eye image signal L and a right-eye image signal R are mixed for every line, a checker box format ( FIG. 4   e ) in which a left-eye image signal L and a right-eye image signal R are mixed for every box, and so on. 
     The OSD generation unit  240  generates an OSD signal directly or in response to a user input. For example, the OSD generation unit  240  may generate a signal for displaying various pieces of information on a screen of the display  180  in the form of graphics or text on the basis of a user input signal. The generated OSD signal may include various data, such as the user interface screen, various menu screens, widgets, and icons of the video display apparatus  100 . The generated OSD signal may further include a 2D object or a 3D object. 
     The mixer  245  may mix the OSD signal generated by the OSD generation unit  240  and a decoded video signal subjected to video processing in the video processing unit  220 . Here, each of the OSD signal and the decoded video signal may include at least one of a 2D signal and a 3D signal. The mixed video signal is provided to the frame rate conversion unit  250 . 
     The frame rate conversion unit (FRC)  250  converts the frame rate of an received video. For example, the frame rate conversion unit  250  converts a frame rate of 60 Hz into a frame rate of 120 Hz or 240 Hz. If the frame rate of 60 Hz is converted into the frame rate of 120 Hz, the first identical frame may be inserted between the first frame and a second frame, or a third frame predicted from the first frame and the second frame may be inserted between the first frame and the second frame. If the frame rate of 60 Hz is converted into the frame rate of 240 Hz, three identical frames may be further inserted, or three predicted frames may be inserted. 
     Meanwhile, the frame rate conversion unit  250  may output a received frame rate without additionally converting the frame rate. If a 2D video signal is received, the frame rate may be preferably outputted without change. Meanwhile, if a 3D video signal is received, the frame rate may be varied as described above. 
     The formatter  260  may receive the signal mixed by the mixer  245  (that is, the OSD signal and the decoded video signal) and separate a 2D video signal and a 3D video signal from the mixed signal. 
     Meanwhile, in this specification, the 3D video signal is meant to include a 3D object. Examples of the object may include a Picture In Picture (PIP) video (a static image or a moving image), an EPG indicating broadcast program information, various menus, widgets, icons, text, things, persons, backgrounds, and web screens (newspaper, magazines, etc.) within a video, and so on. 
     Meanwhile, the formatter  260  may change a format of a 3D video signal. For example, the formatter  260  may change a format of a 3D video signal into any one of the various formats illustrated in  FIG. 4 . In particular, in an embodiment of the present invention, it is assumed that a format of a 3D video signal is changed into the frame sequential format, from among the formats shown in  FIG. 4 . That is, a left-eye image signal L and a right-eye image signal R are sequentially arranged alternately. Accordingly, it is preferred that the additional 3D display  195  of  FIG. 1  be a shutter glasses. 
       FIG. 5  illustrates an operation relationship between the shutter glasses  195  and the frame sequential format.  FIG. 5(   a ) illustrates that, when a left-eye image L is displayed in the display  180 , the left eye glasses of the shutter glasses  195  is opened and the right eye glasses thereof is closed.  FIG. 5(   b ) illustrates that the left eye glasses of the shutter glasses  195  is closed and the right eye glasses thereof is opened. 
     Meanwhile, the formatter  260  may switch a 2D video signal to a 3D video signal. For example, the formatter  260  may detect an edge or a selectable object within a 2D video signal, separate an object or a selectable object according to the detected edge, and generate the object or the selectable object as a 3D video signal according to a 3D video generation algorithm. Here, the generated 3D video signal, as described above, may be separated into a left-eye image signal L and a right-eye image signal R. 
     Meanwhile, an audio processing unit (not shown) within the control unit  170  may perform audio processing on a demultiplexed audio signal. To this end, the audio processing unit (not shown) may include various decoders. 
     For example, if the demultiplexed audio signal is a coded audio signal, the audio processing unit (not shown) may decode the coded audio signal. More particularly, if the demultiplexed audio signal is a coded audio signal according to the MPEG-2 standard, an MPEG-2 decoder may decode the coded audio signal. Furthermore, if the demultiplexed audio signal is a coded audio signal of the MPEG 4 Bit Sliced Arithmetic Coding (BSAC) standard according to a terrestrial Digital Multimedia Broadcasting (DMB) method, an MPEG 4 decoder may decode the coded audio signal. Furthermore, if the demultiplexed audio signal is a coded audio signal of the Advanced Audio Codec (AAC) standard of MPEG 2 according to the satellite DMB method or DVB-H method, an AAC decoder may decode the coded audio signal. Furthermore, if the demultiplexed audio signal is a coded audio signal of the Dolby AC-3 standard, an AC-3 decoder may decode the coded audio signal. 
     The audio processing unit (not shown) within the control unit  170  may process base, treble, volume control, and so on. 
     The data processing unit (not shown) within the control unit  170  may perform data processing on the demultiplexed data signal. For example, if the demultiplexed data signal is a coded data signal, the data processing unit may decode the coded data signal. The coded data signal may be Electronic Program Guide (EPG) information, including pieces of broadcast information, such as the start time, the end time, etc. of a broadcast program which is being broadcasted in each channel. For example, the EPG information may include ATSC-Program and System Information Protocol (ATSC-PSIP) information in case of the ATSC method and may include DVB-Service Information (DVB-SI) information in case of the DVB method. The ATSC-PSIP information or the DVB-SI information may be information included in the above stream (that is, the header (2 byte) of an MPEG-2 TS). 
     Meanwhile, an example where the signals from the OSD generation unit  240  and the video processing unit  220  are mixed by the mixer  245  and then subjected to 3D processing in the formatter  260  is illustrated in  FIG. 2 , but not limited thereto. The mixer may be placed behind the formatter. That is, the output of the video processing unit  220  may be subjected to 3D processing in the formatter  260 , and the OSD generation unit  240  may generate an OSD signal, perform 3D processing, and mix the 3D signal processed by the mixer  245 . 
     Meanwhile, the block diagram of the control unit  170  shown in  FIG. 2  is a block diagram for an embodiment of the present invention. The constituent elements of the block diagram may be integrated, added, or omitted according to the specification of the control unit  170  that is implemented. 
     In particular, the frame rate conversion unit  250  and the formatter  260  may not be included in the control unit  170 , but may be separately provided. 
       FIG. 6  is a diagram illustrating that an image is formed by a left-eye image and a right-eye image, and  FIG. 7  is a diagram illustrating the depth of a 3D video according to the interval between a left-eye image and a right-eye image. 
     Referring to  FIG. 6 , a plurality of videos or a plurality of objects  615 ,  625 ,  635 , and  645  is illustrated. 
     First, the first object  615  is illustrated to include a first left-eye image  611 ,L based on a first left-eye image signal and a first right-eye image  613 ,R based on a first right-eye image signal, and an interval of the first left-eye image  611 ,L and the first right-eye image  613 ,R is illustrated to be d 1  on the display  180 . Here, a user recognizes that an image looks like being formed at a point where a product, connecting a left eye  601  and the first left-eye image  611 , and a product, connecting a right eye  603  and the first right-eye image  613 ,L, cross each other. Accordingly, the user recognizes that the first object  615  is placed behind the display  180 . 
     Next, the second object  625  is illustrated to include a second left-eye image  621 ,L and a second right-eye image  623 ,R, and an interval of the second left-eye image  621 ,L and the second right-eye image  623 ,R is illustrated to be 0 because the second left-eye image  621 ,L and the second right-eye image  623 ,R are overlapped with each other and displayed in the display  180 . Accordingly, a user recognizes that the second object  625  is placed on the display  180 . 
     Next, each of the third object  635  and the fourth object  645  is illustrated to include a third left-eye image  631 ,L and a second right-eye image  633 ,R and a fourth left-eye image  641 ,L and a fourth right-eye image  643 ,R, and intervals thereof are d 3  and d 4 , respectively. 
     According to the above method, a user recognizes that the third object  635  and the fourth object  645  are placed at respective positions where images are formed. In the drawing, a user recognizes that the third object  635  and the fourth object  645  are placed ahead of the display  180 . 
     Here, the fourth object  645  is recognized ahead of the third object  635 , that is, more protruded than the third object  635 . This is because the interval d 4  of the fourth left-eye image  641 ,L and the fourth right-eye image  643 ,R is greater than the interval d 3  of the third left-eye image  631 ,L and the third right-eye image  633 ,R. 
     Meanwhile, in an embodiment of the present invention, the distance between the display  180  and the objects  615 ,  625 ,  635 , and  645  recognized by a user is represented by a depth. Accordingly, a depth when the distance is recognized by a user as if it looks like being placed behind the display  180  is assumed to have a negative value (−), and a depth when the distance is recognized by a user as if it looks like being placed ahead of the display  180  is assumed to have a positive value (−). That is, the degree of depth is increased as the degree of protrusion in a user direction is increased. 
     From  FIG. 7 , it can be seen that, if the interval a between a left-eye image  701  and a right-eye image  702  shown in  FIG. 7(   a ) is smaller than an interval b between a left-eye image  701  and a right-eye image  702  shown in  FIG. 7(   b ), a depth a′ of a 3D object in  FIG. 7(   a ) is smaller than a depth b′ of a 3D object in  FIG. 7(   b ). 
     If a 3D video is illustrated as a left-eye image and a right-eye image as described above, a position where an image is recognized to be formed is changed from a viewpoint of a user according to an interval between the left-eye image and the right-eye image. Accordingly, a depth of a 3D video or a 3D object, consisting of a left-eye image and a right-eye image, may be controlled by controlling a display interval of the left-eye image and the right-eye image. 
       FIG. 8  is a flowchart illustrating a method of operating the video display apparatus according to an embodiment of the present invention, and  FIGS. 9 to 14  are diagrams to which reference is made to describe various examples of the method of operating the video display apparatus shown in  FIG. 8 . 
     Referring to  FIG. 8 , first, video information about a received external video or a received broadcast video is received (S 810 ). 
     The received external video may be an external input video from the external device  190  or a video received from a content provider over a network. Furthermore, the broadcast video may be a broadcast video from a broadcast signal received from the tuber  110 . 
     The video information may be broadcast information about a digital broadcast video (for example, the above ATSC-PSIP information or DVB-SI information) and may be video information about an external input video (for example, HDMI SI (system information) information). It is hereinafter assumed that the video information is an external input video received from the external device  190 . 
     The external input video received from the external device  190  is inputted to the control unit  170  via the external device interface unit  130  and then subjected to signal processing. Here, it is important to check whether the external input video is a 2D video or a 3D video rapidly and simply because a decoder used upon decoding in the video processing unit  220  (in particular, the video decoder  225 ) within the control unit  170  is changed according to whether the external input video is the 2D video or the 3D video. 
     The external device interface unit  130  may receive not only the external input video from the external device  190 , but also video information about the external input video. 
     The video information about the external input video may be, for example, transmission-related information (for example, a Display Data Channel (DDD)) between the external device  190  and the external device interface unit  130  within the video display apparatus  100 , information indicating whether the external input video is a 2D video or a 3D video or the like. 
     Here, the transmission-related information may include information about the specification of the video display apparatus  100  (sink device) and about the representation ability of the video display apparatus  100  (sink device). For example, the transmission-related information may include information about whether the video display apparatus  100  can display a 3D video and about what is a 3D video format if the 3D video can be displayed. An external device may receive the transmission-related information from the video display apparatus  100 . 
     Meanwhile, the transmission-related information of the video display apparatus  100  may be checked based on Extended Display Identification Data (EDID) within the video display apparatus  100 . That is, the information about the specification, ability, etc. of the video display apparatus  100  may be checked through the EDID. 
     Meanwhile, the information indicating whether the external input video is a 2D video or a 3D video may be included in the header of a packet which is received by the external device interface unit  130 , as shown in  FIG. 11 . 
       FIG. 11  illustrates HB 0  1 byte (8 bits) and HB 1  of 1 byte within a packet header. For example, if a value of HB 0  within the packet header has a binary number ‘1011’ (that is, a value of ‘11’ in a decimal value) as shown, the value of HB 1  may be defined to indicate 3D video information. Meanwhile, if the value of HB 0  within the packet header is not the value of ‘11’, the value of HB 1  may be checked not to be 3D video information. 
     Meanwhile, the 3D video information HB 1  may include information NO — 3DM_Packet indicating whether 3D metadata exists within the packet, application validity information Valid_IN_Next indicating whether the 3D metadata is validly applicable in a next video frame or whether a received external video or a broadcast video is converted in the next video frame, target group information Current_GR# to which the received external video or the broadcast video belongs, and application group information Affected_GR# to which the 3D metadata is applied. 
     Here, the information NO — 3DM_Packet indicating whether 3D metadata exists is represented by 1 bit. If the information NO — 3DM_Packet has a value ‘1’, it means that the 3D metadata does not exist in the packet. If the information NO — 3DM_Packet has a value ‘0’, it means that the 3D metadata exists in the packet. 
     Here, the 3D metadata may be placed in the header and payload of a packet, as described later with reference to  FIG. 13 . 
     Furthermore, the 3D metadata may include 3D format information illustrated in  FIG. 4 , a 3D coding method such as MVC or AVC, group information to which a corresponding packet is applied, etc. 
     Meanwhile, if the NO — 3DM_Packet has the value of ‘1’, it means that 3D metadata does not exist within the packet, but 2D data including the title of a video, etc. within a packet may be included. 
     Meanwhile, the NO — 3DM_Packet may be selectively included in the packet header, but it is preferred that the NO — 3DM_Packet be included as in the drawing before being converted into a 3D input or in case of a 3D mode. Accordingly, the NO — 3DM_Packet may also be used as a flag for checking a 2D video input and a 3D video input. 
     Next, the application validity information Valid_IN_Next is represented by 1 bit. The application validity information of ‘1’ may indicate that 3D metadata is validly applicable in a next video frame, and the application validity information of ‘0’ may indicate that 3D metadata is invalidly applicable in a next video frame. 
     That is, the application validity information may mean whether the application group information GR# included in metadata, in particular, 3D metadata is identical with the group information GR# of a next video frame. Accordingly, if they are identical with each other, the application validity information may have ‘1’, and if they are not identical with each other, the application validity information may have ‘0’. 
     Furthermore, if the application group information Affected_GR# and the target group information Current_GR# are not identical with each other in the state where the application validity information Valid_IN_Next is ‘1’, it means that conversion is generated in a next video frame. If they are identical with each other, it may mean that conversion is generated in a corresponding video frame. 
     Next, the application group information Affected_GR# is represented by 3 bits, and it indicates a group index to which 3D metadata is applied. 
     Next, the target group information Current_GR# is represented by 3 bits, and it indicates a group index of a target video frame now being received. 
     Next, if the received video information is 3D video information (S 820 ), conversion information between a 2D video and a 3D video within the 3D video information is detected (S 830 ). 
     The conversion information is information indicating that the received external video or the broadcast video is converted from a 2D video to a 3D video or from a 3D video to a 2D video. For example, the conversion information is chiefly applied when an external video or a broadcast video received from the external device  190  is a mixture of a 2D video and a 3D video. 
     The conversion information may have one piece of information, but, in an embodiment of the present invention, may be calculated by a combination of a plurality of pieces of information. 
     The conversion information may include the information NO — 3DM_Packet indicating whether 3D metadata exists in the 3D video information HB 1  as described above. The conversion information may further include the application validity information Valid_IN_Next and the application group information Affected_GR#. 
     Consequently, as shown in  FIG. 10 , the detection of the conversion information may be performed by detecting the information NO — 3DM_Packet indicating whether 3D metadata exists, the application validity information Valid_IN_Next, and the application group information Affected_GR# as described above. 
     Next, the received external video or the received broadcast video is subjected to 2D signal processing or 3D signal processing based on the conversion information (S 840 ). 
       FIG. 12  shows an example of external input videos, and  FIG. 13  illustrates values of 3D video information HB 1  including conversion information according to  FIG. 12 . 
       FIGS. 12 and 13  sequentially illustrate a 2D video  1310 , a 2D video  1320 , a 3D video  1330 , . . . , a 3D video  1350 , and a 2D video  1360 . 
     The target group information Current_GR# is determined according to whether the received external video or the broadcast video is a 2D video or a 3D video. Accordingly, the 2D video  1310  and the 2D video  1320  are made to have GR# 0  of a binary number ‘000’, the 3D video  1330 , . . . , the 3D video  1350  are made to have GR# 1  of a binary number ‘001’, and the 2D video  1360  is made to have GR# 2  of a binary number ‘010’. 
     Meanwhile,  FIG. 13(   c ) illustrates that a packet includes a header and a payload. Each packet, in particular, the payload is illustrated to include 3D metadata having group information to which the packet is applied. Meanwhile, the payload may further include 2D metadata in addition to 3D metadata. 
     Meanwhile, the received external video or the received broadcast video is received in synchronism with a vertical synchronization signal Vsync. When the received external video or the received broadcast video is received, video information about the external video or the broadcast video is received separated from the external video or the broadcast video. Here, the video information may include a header and a payload in the form of a packet. 
     In the drawing, pieces of video information ( 1 ) to ( 6 ) about each of six external videos or six broadcast videos are combined in six vertical synchronization frequencies. 
     In the pieces of video information ( 1 ), ( 4 ), ( 5 ), and ( 6 ) of the pieces of video information ( 1 ) to ( 6 ), the group information (=GR#) to which 3D metadata within a payload is applied may have any value because the information NO — 3DM_Packet indicating whether 3D metadata exist has a value of ‘1’. Accordingly, each bit is illustrated to be ‘d’ as in the drawing. 
     Meanwhile, in case of ( 2 ) and ( 3 ), the information NO — 3DM_Packet indicating whether 3D metadata exists has a value of ‘0’. 
     From among them, in case of ( 2 ), 3D metadata exists in the packet, the group information 3DM_GR# to which the packet of 3D metadata is applied is a binary number ‘001’ (=GR# 1 ), the application group information Affected_GR# is a binary number ‘001’ (=GR# 1 ), and the target group information Current_GR# is a binary number ‘000’=GR# 0 , Since the group information (=GR# 1 ) to which 3D metadata is applied is identical with the group information (=GR# 1 ) of a next video frame, the application validity information Valid_IN_Next has a value of ‘1’. Meanwhile, since the group information (=GR# 1 ) to which 3D metadata is applied corresponds to a 3D video as the external video  1320  later, the information NO — 3DM_Packet indicating whether 3D metadata exists may have a value of ‘0’. 
     Meanwhile, in ( 2 ), video conversion is performed in a next frame because the application group information (=GR# 1 ) is different from the target group information=GR#0 in the state where the application validity information Valid_IN_Next is ‘1’. That is, video is converted into the 3D video  1330  in a next video frame in the state where the received external video  1310  is a 2D video. 
     Meanwhile, in ( 3 ), video conversion is performed with constant delay in the state where the application validity information Valid_IN_Next is ‘1’ because the application group information (=GR# 1 ) is identical with the target group information (=GR# 1 ). 
     Meanwhile, in ( 4 ), the group information 3DM_GR# to which a relevant packet of 3D metadata is applied may have any value. However, for example, if the group information has a binary number ‘010’ (=GR# 2 ), the application group information Affected_GR# is a binary number ‘010’ (=GR# 2 ), the target group information Current_GR# is a binary number ‘001’ (=GR# 1 ), the received external video  1340  is a 3D video, and the application validity information Valid_IN_Next has a value of ‘0’ because video conversion is not generated in a next video frame. That is, since the group information (=GR# 2 ) to which 3D metadata is applied is different from the group information (=GR# 0 ) of the next video frame, the application validity information Valid_IN_Next has ‘0’. Meanwhile, since the group information (=GR# 2 ) to which 3D metadata is applied does not correspond to a 3D video as the next external video  1320 , the information NO — 3DM_Packet indicating whether 3D metadata exists may have a value of ‘1’. 
     From among them, in ( 3 ), it can be seen that a 2D video is converted into a 3D video. 
     Meanwhile, if the Valid_IN_Next=‘1’, the target group information Current_GR#, and the application group information Affected_GR# are not identical in the state where the application validity information Valid_IN_Next is validly applicable in a next video frame (( 2 ) and ( 5 )), a ready bit for conversion in a next video frame is set. Accordingly, conversion is performed in the next video frame. 
     In other words, if the Valid_IN_Next=‘1’, the target group information Current_GR#, and the application group information Affected_GR# are not identical in the state where the application validity information Valid_IN_Next indicates that it is validly applicable in a next video frame ( 2 ), conversion between a 2D video and a 3D video is performed with constant delay in a next frame ( 3 ). Accordingly, 2D video being processed in the control unit  170  is converted into 3D video processing, or 3D video being processed in the control unit  170  is converted into 2D video processing. 
     As described above, if the conversion information, including the application validity information Valid_IN_Next, the target group information Current_GR#, and the application group information Affected_GR#, is used, conversion between 2D and 3D in an external video received from the external device  190  or a broadcast video received from tuber  110  can be checked simply and easily. 
     Meanwhile, if the application validity information Valid_IN_Next indicates that it is invalidly applicable in a next video frame (Valid_IN_Next=‘0’) ( 4 ), signal processing is performed without additionally converting a received external video or a received broadcast video. That is, the control unit  170  continues to perform 3D video processing. 
     Meanwhile,  FIGS. 9 , and  10  are flowcharts illustrating the above-described operations. 
       FIG. 9  sequentially illustrates signal processing between the remote control apparatus  200 , the external device  190 , the external device interface unit  130 , the control unit  170 , and the display  180 . 
     First, the permitted capacity or capability of the external device interface unit  130  is checked between the external device  190  and the external device interface unit  130  connected to each other (S 905 ), and information about the external device interface unit  130  is transmitted to the external device  190  (S 910 ). 
     Accordingly, the external device interface unit  130  activates a 3D interrupt (S 915 ). 
     Meanwhile, when a user plays content within the external device  190  through the remote control apparatus  200  (S 920 ), the external device  190  hands a video of played content and video information to the external device interface unit  130  (S 925 ). Next, the external device interface unit  130  informs the control unit  170  that the corresponding video is a 2D video, if the corresponding video is checked to be the 2D video based on the received video and the received video information (S 930 ). Accordingly, the control unit  170  performs 2D signal processing (decodes) on the received video and provides the resulting video to the display  180  (S 935 ). 
     Meanwhile, the external device  190  continues to hand a video of played content and relevant video information to the external device interface unit  130  (S 940 ). Next, if the corresponding video is checked to be a 3D video based on the received video and the video information, the external device interface unit  130  informs the control unit  170  that the corresponding video is the 3D video (S 945 ). Accordingly, the control unit  170  performs 3D signal processing (decodes) on the received video through conversion of signal processing and provides the resulting video to the display  180  (S 950 ). 
     The external device  190  continues to hand a video of played content and relevant video information to the external device interface unit  130  (S 955 ). If the corresponding video is checked to be a 2D video based on the received video and the video information, the external device interface unit  130  informs the control unit  170  that the corresponding video is the 2D video (S 960 ). Accordingly, the control unit  170  performs 2D signal processing (decodes) on the received video through conversion of signal processing and provides the resulting video to the display  180  (S 965 ). 
     Furthermore, if there is a content play stop or power-off signal received from the remote control apparatus  200  (S 970 ), the external device  190  informs the external device interface unit  130  that the external device  190  has been unplugged (S 975 ), the external device interface unit  130  informs the control unit  170  that the external device  190  has been unplugged (S 980 ), and the control unit  170  transfers, to the display, that the external device  190  has been unplugged (S 985 ). 
       FIG. 10  illustrates signal processing according to the reception of 3D video information between the external device interface unit  130  and the control unit  170  within the video display apparatus  100 . That is, this drawing illustrates signal processing on the packet header of  FIG. 11 . 
     First, as in the step (S 915 ), the external device interface unit  130  activates a 3D interrupt (S 1110 ). Accordingly, the external device interface unit  130  is prepared to receive a video and information about the video which are received from the external device  190 . 
     Next, the external device interface unit  130  receives 3D metadata (S 1020 ). If a value of HB 0  of a packet header shown in  FIG. 11  is ‘11’ as described above, the external device interface unit  130  receives 3D video information HB 1  within the packet header as 3D metadata. 
     It is then determined whether the information NO — 3DM_Packet indicating whether 3D metadata exists in the header has a value of ‘1’ (S 1025 ). 
     If the information NO — 3DM_Packet has the value of ‘1’, it is determined that the 3D metadata does not exist, and thus data processing on 3D metadata is not performed. For example, an external input video may be considered as a 2D video and conversion to a 2D mode may be immediately performed (S 1030 ). Accordingly the control unit  170  performs 2D signal processing on the received video. 
     Meanwhile, if the information NO — 3DM_Packet have a value of ‘0’, the 3D metadata is determined to exist, and thus steps subsequent to step S 1035  are performed. 
     It is then determined whether the application validity information Valid_IN_Next within the header has a value of ‘1’ (S 1035 ). 
     If the application validity information Valid_IN_Next has the value of ‘1’ (that is, it indicates that an application is valid in a next video frame), it is determined whether the target group information Current_GR# and the application group information Affected_GR# within the 3D metadata are identical with each other (S 1040 ). 
     If the target group information Current_GR# and the application group information Affected_GR# within the 3D metadata are not identical with each other in the state where the application validity information Valid_IN_Next has the value of ‘1’, a ready bit is set because conversion between 2D and 3D is performed after a next frame (S 1050 ). Accordingly, the control unit  170  is prepared to perform a conversion operation. 
     Meanwhile, if the target group information Current_GR# and the application group information Affected_GR# within the 3D metadata are identical with each other in the state where the application validity information Valid_IN_Next has the value of ‘1’, conversion between 2D and 3D is performed with constant delay (S 1045 ). Accordingly, the control unit  170  performs 3D signal processing on a received video, being subjected to 2D signal processing, or 2D signal processing on the received video, being subjected to 3D signal processing, by performing the conversion operation. 
     Meanwhile, if the application validity information Valid_IN_Next has a value of ‘0’, the control unit  170  stores 3D metadata without an additional conversion operation and maintains a current state (S 1050 ). That is, the control unit  170  maintains a current state without a change of signal processing. Meanwhile, the stored 3D metadata may be used to compare the stored 3D metadata with another 3D metadata when a subsequent frame is received. 
     Meanwhile, the step S 1020  may continue to be performed subsequently to the steps S 1045 , S 1050 , and S 1055 . That is, 3D metadata within a packet subsequently received is received. Next, the operations subsequent to the step S 1020  may be repeated. 
     Meanwhile, at the time of the conversion, an object indicating the conversion is displayed in the display (S 850 ). 
       FIG. 14  illustrates that, when a 2D video  1410  is displayed in the display  180  ( FIG. 14  ( a )) and externally received content is converted into 3D, an object  1415  indicating the conversion is displayed in the display  180  ( FIG. 14  ( b )), a screen  1420  where a 3D format suitable for 3D watching can be selected at the time of the conversion is displayed in the display  180  ( FIG. 14  ( c )), and a 3D video  1430  including an object  1435  that looks like being protruded is displayed in the display  180  ( FIG. 14  ( c )). 
     In case of conversion from 2D to 3D and from 3D to 2D as described above, an object indicating the conversion is displayed in the display, so that a user can easily check the conversion. In particular, if the additional 3D display  195  is used, a point of time at which the additional 3D display  195  is worn or taken off can be accurately known. 
     Furthermore, as shown in  FIG. 14(   c ), an object  1421  indicating the top/down format, an object  1423  indicating the side-by-side format, and an object  1425  indicating the checker box are illustrated. In addition, objects for various formats may be further displayed as shown in  FIG. 4 . Accordingly, a user may select a 3D format most suitable for 3D watching and watch a 3D video by selecting the format. 
     The video display apparatus and the method of operating the same according to the present invention are not limited and applied to the constructions and methods of the embodiments described as above, but all or some of the embodiments may be selectively combined and configured so that the embodiments may be modified in various ways. 
     Meanwhile, the method of operating the video display apparatus according to the present invention may be implemented in a recording medium, readable by a processor included in the video display apparatus, in the form of processor-readable codes. The processor-readable recording medium may include all kinds of recording devices in which processor-readable data is stored. The processor-readable recording medium may include, for example, ROM, RAM, CD-ROM, magnetic tapes, floppy disks, and optical data storages and may also include carrier wave forms, such as transmission over the Internet. Furthermore, codes, distributed into computer systems connected over a network and readable by the processor, may be stored and executed in the processor-readable recording medium in a distributed manner. 
     Furthermore, although the preferred embodiments of the present invention have been shown and described, the present invention is not limited to the above specific embodiments, and a person having ordinary skill in the art to which the invention belongs may modify the embodiments in various ways without departing from the gist of the present invention which is written in the claims. The modified embodiments should not be interpreted individually from the technical spirit or prospect of the present invention.