Patent Publication Number: US-8542621-B2

Title: Method of and apparatus for providing and receiving video service in digital audio broadcasting

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2005-0121253, filed on Dec. 10, 2005 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Apparatuses and methods consistent with the present invention relate to digital audio broadcasting (DAB), and more particularly, to providing and receiving a video service in DAB. 
     2. Description of the Related Art 
     Analog audio broadcasting has drawbacks in that the quality of a signal input to an analog audio receiver significantly deteriorates when the analog audio receiver is moving; power efficiency is poor since strong transmission power is required to hide noise; and spectrum efficiency is poor due to the use of different frequencies in neighboring regions to eliminate channel interference. To address these problems, research into digital audio broadcasting (DAB) as a substitute for existing analog radio broadcasting, such as amplitude modulation (AM) and frequency modulation (FM) radio broadcasting, has been conducted. The European Telecommunication Standardization Institute (ETSI) has established the ETSI EN 300 401 standard for DAB. 
     ETSI EN 300 401, also called EUREKA-147, describes the provision of audio service and various additional services having compact disc (CD)-level quality at a bandwidth of about 2 MHz using a high-quality audio compression technique according to Moving Picture Experts Group (MPEG)-1 audio layer II. A plurality of audio data services are transmitted using Unequal Error Protection (UEP) and a plurality of data services are transmitted using Equal Error Protection (EEP) so as to optimize rates of data transmission at limited bandwidth and in a channel environment. 
     Through DAB, high-quality multi-channel audio and various types of additional data can be transmitted. Examples of additional data include still images, moving images, and graphics data. By transmitting the additional data, it is possible to provide multimedia services such as travel and traffic information, a program linkage information service that provides news images combined with headline characters or weather forecast and traffic information combined with electronic maps, a program independent information service that provides web site broadcasting or a Global Positioning System (GPS) for DAB, and a moving image service. 
     Among those services, an audio service, a packet mode data service, and a stream mode data service are provided according to the DAB standard (ETSI EN 300 401), but a video service using the stream mode data service is not prescribed in the DAB standard. As a result, for transmission/reception of video data, the DAB standard needs to be amended. This is because, in this case, although a separate standard determining a transmission method of a broadcasting station and a reception method of a receiver should be agreed between the broadcasting station and the receiver, a receiver that does not adhere to the standard cannot be provided with the video service through a DAB stream mode. 
     When the video service is provided using the stream mode data service that is a main service channel, encoding parameters related to the video service and information regarding a method used to packetize video data are generally included in a video service stream. Thus, for the video service, the encoding parameters used to encode data related to the video service and the method used to packetize the video data should be capable of determination by decoding the main service channel of DAB. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of and apparatus for providing and receiving a video service, in which the video service can be provided through a stream mode in digital audio broadcasting (DAB). 
     According to an aspect of the present invention, there is provided a method of providing a video service in DAB. The method includes inserting a profile identifier (ID) that specifies an encoding method used to encode a provided video service stream and program type information that indicates a type of the provided video service stream into a fast information channel (FIC) that is different from a service data channel comprising the video service stream; and multiplexing the service data channel and the FIC into a transmission frame for transmission. 
     The transmission frame may be a DAB transmission frame and the video service stream may comprise a video data stream or an audio data stream, or both audio and video data streams. 
     The profile ID may comprise information that specifies a video coding method. 
     The FIC may comprise fast information blocks (FIBs) of a predetermined size and a data field of each of the FIBs comprises at least one fast information group (FIG). 
     The FIC may comprise FIBs of a predetermined size, a data field of each of the FIBs comprises at least one FIG and the profile ID and the program type information are included in a single FIG. 
     According to another aspect of the present invention, there is provided a method of receiving a video service in DAB. The method includes receiving a DAB transmission frame and analyzing an encoding method and a program type of a received encoded video service stream based on a profile ID and program type information included in a fast information channel FIC of the DAB transmission frame that is received; and decoding the encoded video service stream included in a service data channel that is different from the FIC according to the encoding method and the program type that are analyzed. 
     According to still another aspect of the present invention, there is provided an apparatus for processing a video service in DAB. The apparatus includes an analyzing unit that receives a DAB transmission frame and analyzes an encoding method and a program type of a received encoded video service stream based on a profile ID and program type information included in a FIC of the DAB transmission frame that is received; and a video service decoder driving unit driving a decoder that decodes the encoded video service stream included in a service data channel that is different from the FIC according to the encoding method and the program type that are analyzed. 
     According to yet another aspect of the present invention, there is provided a transmitter for providing a video service in DAB. The transmitter includes an encoder that encodes the video service as a provided video service stream in a service data channel according to an encoding method; and a FIC processing unit which generates a profile ID that specifies the encoding method used to encode the provided video service stream and program type information that specifies a type of the provided video service stream in an FIC, wherein the service data channel is different from the FIC and comprises the provided video service stream, which is encoded according to the encoding method that is specified by the profile ID, and wherein the transmitter transmits the service data channel that comprises the video service stream and the FIC that comprises the profile ID and the program type information in a transmission data frame. 
     According to yet another aspect of the present invention, there is provided a method of providing a video service in DAB. The method includes inserting information that specifies a main component of a provided video service stream into a predetermined channel that is different from a service data channel that comprises the video service stream; and multiplexing the service data channel and the predetermined channel into a transmission frame for transmission. 
     According to yet another aspect of the present invention, there is provided a method of receiving a video service in DAB. The method includes receiving a DAB transmission frame, and analyzing information that specifies a main component of a provided video service stream, included in a predetermined channel of the DAB transmission frame that is received, which is different from a service data channel; and selectively decoding streams included in the video service stream based on the encoding method and the program type that are analyzed. 
     According to yet another aspect of the present invention, there is provided an apparatus for processing a video service in DAB. The apparatus includes an analyzing unit that receives a DAB transmission frame and analyzes information that indicates a main component of a provided video service stream included in a predetermined channel of the DAB transmission frame that is received, which is different from a service data channel; and a video service decoder driving unit driving a decoder that selectively decodes streams included in the video service stream according to the encoding method and the program type that are analyzed. 
     According to yet another aspect of the present invention, there is provided a transmitter for providing a video service in DAB. The transmitter includes a FIC processing unit that generates information that specifies a main component of a provided video service stream in an FIC; and a service data channel processing unit that processes the provided video service stream in a service data channel, wherein the transmitter transmits the service data channel that comprises the video service stream and the FIC that comprises the profile ID and the program type information in a transmission data frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
         FIG. 1  is a block diagram of transmitter that provides a video service in a digital audio broadcasting (DAB) system according to an exemplary embodiment of the present invention; 
         FIG. 2  illustrates service components and sub-channels of a single DAB ensemble according to an exemplary embodiment of the present invention; 
         FIG. 3  illustrates a selection of content including a multi-structure and a fast information group (FIG) that stores configuration information regarding ensembles, services, and service components according to an exemplary embodiment of the present invention; 
         FIG. 4  illustrates the structure of a DAB transmission frame according to an exemplary embodiment of the present invention; 
         FIG. 5  is a detailed block diagram of a video service encoder for providing a video service according to an exemplary embodiment of the present invention; 
         FIG. 6  is a detailed block diagram of a video service encoder for providing a video service, in which video service data is configured with IP packets according to an exemplary embodiment of the present invention; 
         FIG. 7  illustrates the structure of an MPEG-2 transport stream (TS) packet generated by inserting synchronization data and error correction data according to an exemplary embodiment of the present invention; 
         FIG. 8  illustrates the structure of a fast information block (FIB) according to an exemplary embodiment of the present invention; 
         FIG. 9  illustrates the structure of a FIG type  0  according to an exemplary embodiment of the present invention; 
         FIG. 10  illustrates the structure of a FIG.  0 / 2  according to an exemplary embodiment of the present invention; 
         FIG. 11A  illustrates the detailed structure of a user application filed of a FIG.  0 / 13  according to an exemplary embodiment of the present invention; 
         FIG. 11B  illustrates the structure of a newly defined FIG for video service encoding parameters according to an exemplary embodiment of the present invention; 
         FIG. 12  illustrates a data structure including video service encoding parameter information and packetization information including profile information and other information according to an exemplary embodiment of the present invention; 
         FIG. 13  illustrates a frame structure according to an exemplary embodiment of the present invention; 
         FIG. 14  illustrates a program type code table used in an exemplary embodiment of the present invention; 
         FIG. 15  is a block diagram of a receiver that receives a video service in a DAB system according to an exemplary embodiment of the present invention; 
         FIG. 16  is a detailed block diagram of a video service control unit of  FIG. 5  according to an exemplary embodiment of the present invention; 
         FIGS. 17A and 17B  are flowcharts illustrating a method of providing a video service according to an exemplary embodiment of the present invention; 
         FIG. 18  is a flowchart illustrating a method of receiving a video service in a DAB receiver according to an exemplary embodiment of the present invention; 
         FIG. 19  illustrates a frame structure according to another exemplary embodiment of the present invention; and 
         FIG. 20  is a flowchart illustrating a method of receiving a video service in a DAB receiver according to another exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a block diagram of a transmitter in a digital audio broadcasting (DAB) system that provides a video service according to an exemplary embodiment of the present invention. 
     The DAB system transmits not only audio service data but also video service data and additional service data. Thus, the DAB system includes a video service encoder  110 , an audio service encoder  120 , and an additional data service encoder  130 . Audio service data to be broadcast, such as speech data or music, is input to the audio service encoder  120  to be encoded and channel-coded and the encoded data is then input to a main service channel (MSC) multiplexer  140 . Since the DAB system can provide a plurality of audio services, it may include a plurality of audio service encoders  120 . 
     Data such as character information and web information other than audio data is classified as packet mode data. The packet mode data is input to the additional data service encoder  130  to be encoded and channel-coded and is then input to the MSC multiplexer  140 . Since the DAB system can provide a plurality of packet mode data services, it may also include a plurality of additional data service encoders  130 . 
     In the DAB system, signals composing a video service include an audio signal, a video signal, and an additional data signal. Video service data including data of the video signal itself, such as a movie or a drama, additional data (e.g., subtitle data) related to the video signal, or packet mode data according to the DAB standard, such as character information, traffic information, still images, and web information, is classified as stream mode data, is input to the video service encoder  110  to be encoded into stream mode data and channel-coded, and is then input to the MSC multiplexer  140 . 
     The MSC multiplexer  140  multiplexes the audio service, the packet mode data service, and the stream mode data service and adds corresponding additional information and multiplexing information and then synchronization information to each of the audio service, the packet mode data service, and the stream mode data service, thereby generating and outputting a DAB transmission frame. The DAB transmission frame passes through an orthogonal frequency division multiplexing (OFDM) modulator  150  and an amplifier  160  and is transmitted via very high frequency (VHF)-band waves. A DAB receiver may be of a fixed, portable, or mobile type. 
       FIG. 2  illustrates service components and sub-channels of a single DAB ensemble according to an exemplary embodiment of the present invention. 
     An ensemble generally denotes a bitstream obtained by channel-coding several encoded audio streams and a plurality of pieces of data and by multiplexing the channel-coded data with system data. Services generally denote outputs such as a program service or a data service selected by a user. Service components generally denote elements of the services. The service components of a service are linked to one another based on multiplex configuration information (MCI). Each of the service components is transmitted via a sub-channel SubCh or a fast information data channel (FIDC). 
     Referring to  FIG. 2 , “DAB ENSEMBLE ONE” generally denotes an example of a DAB ensemble that includes three services entitled “alpha1 radio”, “beta radio”, and “alpha2 radio”. Each of the three services includes service components. For example, the “alpha1 radio” service includes service-components such as an audio service component, a traffic message channel (TMC) service component (i.e., ALPHA-TMC), and a service information (SI) service component (i.e., ALPHA-SI). These service components are transmitted via corresponding sub channels. For example, if the “alpha1 radio” service is a sports service, audio data broadcast on “alpha1 radio” is linked to the audio service component, related character information is linked to ALPHA-TMC, and information regarding the “alpha1 radio” is linked to ALPHA-SI. Here, SI denotes service information and TMC denotes a traffic message channel through which traffic information is supplied in real time. 
     The configurations of the services and their service components can be obtained from the MCI. In other words, the MCI specifies the service components of the respective services and thus allows a DAB receiver to analyze the service components. For example, when a user receives the ALPHA-TMC, the DAB receiver analyzes the MCI, recognizes that the ALPHA-TMC is transmitted via the fast information data channel (FIDC), reads information from the FIDC of a fast information channel (FIC), and provides “alpha1 radio” to the user. The FIDC is available for transmission of a small size of data to be transmitted within a predetermined time. 
     Since the service components are contained and transmitted in corresponding sub-channels, a sub-channel may be arbitrarily constructed by a service provider, and a pre-set sub-channel may be reconstructed when there is a change in the channel capacity or the services. If information regarding one of the sub-channels or one of the services is changed, new MCI is transmitted before transmission of the service so that the DAB receiver can properly receive the changed service. 
       FIG. 3  illustrates a selection of content including a multi-structure and a FIG that stores configuration information regarding ensembles, services, and service components according to an exemplary embodiment of the present invention. 
     A FIG is a bundle of data used by an application in a FIC. Referring to  FIG. 3 , one service includes several service components and can be provided with various applications included in and transmitted via sub-channels corresponding to a sub-channel ID or a service component ID. DAB describes the structure of such a service using the FIC. Accordingly, to receive a service selected by a user, information regarding a destination channel of the selected service and the channel size (i.e., sub-channel information) is obtained from the MCI carried over the FIC, and the selected service is provided to the user or displayed on a screen. FIGs constitute a fast information block (FIB) that is carried over the FIC regarding a service, and thus, an analysis of the FIG structure provides information regarding the service. 
       FIG. 4  illustrates a DAB transmission frame according to an exemplary embodiment of the present invention. 
     The DAB transmission frame includes a synchronization channel (SC)  410 , a FIC  420 , and an MSC  430 . 
     The SC  410  includes a null symbol that allows selection of a transmission mode, and a reference symbol required for OFDM symbol synchronization and carrier frequency synchronization. The FIC  420  is used to transmit information required by a DAB receiver to process data (e.g., information regarding service structure or the structure of multiplexed service data, or data that must be quickly transmitted). The FIC  420  contains MCI specifying the structures of sub-channels, and SI, which includes additional information regarding the services. Accordingly, the type of channel reveals the type of service data transmitted via the MSC  430  and the type of application that will use the service. The FIC  420  may further contain data that must be quickly transmitted within a predetermined time (e.g., FIDC data). For instance, short emergency messages can be transmitted via the FIC  420 . FIG structures constituting the FIC  420  will be described later with reference to  FIG. 8 . 
     Substantial content data provided by a service provider is transmitted through the MSC  430 . If the FIC  420  cannot accommodate all the data for an FIC, FIC data can be partially included in the MSC  430 . However, since time interleaving is applied to the MSC  430 , a time delay occurs during the decoding of data. For this reason, FIC data that needs to be quickly transmitted is preferably not included in the MSC  430 . Data can be transmitted in a stream mode or a packet mode. In the stream mode, data is transmitted at a fixed bit rate without an additional header in a given sub-channel. In the packet mode, data is transmitted together with a header, and thus, various service components can be multiplexed in a given sub-channel. Accordingly, analysis of a header of a packet is further required in the packet mode to extract the data from a combination of the data and the header. 
       FIG. 5  is a detailed block diagram of the video service encoder  110  for providing a video service according to an exemplary embodiment of the present invention. 
     A video signal is encoded by a video encoder  502 , an audio signal is encoded by an audio encoder  504 , and an additional data signal is encoded by an additional data encoder  506 . 
     Packet mode data such as character information, traffic information, still images, and web information transmitted according to a packet mode of DAB may be used as additional data in a packetized form according to a corresponding standard. When packet data transmitted as the packet mode data of the DAB is transmitted as additional data of the video service, error correction is performed by an error resiliency processing unit  530  included in the video service encoder  110  for channel error resilient transmission, thereby reducing transmission errors compared to conventional transmission according to the packet mode. 
     The video encoder  502  records information regarding an encoding method used to encode an input video signal. For example, if the input video signal is encoded using MPEG-4 video coding, then the size, MPEG-4 profile, and level of an input video are recorded in a header of an encoded video stream. Such information regarding video encoding is parameterized and output. The audio encoder  504  also records information regarding an encoding method used to encode an input audio signal. For example, if the input audio signal is encoded using MPEG-4 audio coding, then the sampling rate and the number of channels of an input audio are recorded in a header of an encoded audio stream. The information regarding audio encoding is also parameterized and output. 
     The additional data encoder  506  parameterizes and outputs information regarding the type of an input additional data signal that is packet mode data, such as character information, traffic information, still images, and web information or encoded general additional data. 
     The video service encoder  110  receives an encoded video stream, an encoded audio stream, and an encoded additional data stream to generate a video service stream, multiplexes the video service stream with other service data through the MSC multiplexer  140 , and transmits the multiplexed data in a stream mode. The video service encoder  110  includes a time synchronization information inserting unit  510 , a multiplexing unit  520 , and an error resiliency processing unit  530 . 
     The time synchronization information inserting unit  510  inserts time synchronization information to allow audio data of the encoded audio stream, video data of the encoded video stream, and the video data stream to be reproduced in synchronization with one another. In other words, since the video encoder  502 , the audio encoder  504 , and the additional data encoder  506  encode input data independent of each other, information regarding the output of encoded data in connection with the other input data is not included, which results in a need to additionally provide time synchronization information. For example, when a method defined in the MPEG-4 synchronization layer (SL) is used, time synchronization information is inserted into an MPEG-4 SL header to add the time synchronization information to each of the encoded video stream, the encoded audio stream, and the encoded additional data stream, respectively. The time synchronization information is also parameterized and output. 
     The multiplexing unit  520  multiplexes the encoded audio stream, the encoded video stream, and the encoded additional data stream, each of which includes the time synchronization information, into a single TS. The multiplexing unit  520  may perform multiplexing using various methods. For example, in the case of multiplexing using an MPEG-2 TS, the multiplexing unit  520  generates and multiplexes a 188-byte MPEG-2 TS packet. A program ID (PID) of data included in the MPEG-2 TS packet is recorded in the multiplexed TS. Such multiplexing information including the PID is also parameterized and output. 
     The multiplexed TS is input to the error resiliency processing unit  530  to handle a transmission error. The error resiliency processing unit  530  includes an error correction coding unit  532  and an interleaver  534 . 
     The error correction coding unit  532  adds error correction data to the end of payload data to be transmitted. The interleaver  534  rearranges the position of each byte of a TS to which the error correction data is added using convolutional interleaving. For example, when the multiplexed TS is an MPEG-2 TS, the size of a single MPEG-2 TS packet is 188 bytes and the error correction data is added to the end of 188 bytes. The error correction coding unit  532  may generate the error correction data using Reed-Solomon coding and the interleaver  534  may use convolutional interleaving. Information about an error correction coding method and an interleaving method is also parameterized and output. 
     Such an error-resilient TS processed by the error resiliency processing unit  530  is transmitted by the MSC multiplexer  140  over the MSC of DAB. 
     The parameterized information is called video service encoding parameters that are input to a video service control unit  550 . The video service control unit  550  transmits the video service encoding parameters to a FIC processing unit  560  for transmission over the FIC, and the FIC processing unit  560  codes the video service encoding parameters and transmits the coded video service encoding parameters over the FIC. Among the received video service encoding parameters, encoding information of the video signal and the audio signal is recorded as a profile in the FIC. The error correction coding method and the interleaving method used in the error resiliency processing unit  530  are recorded in a data service component type (DSCTy) field of a FIG.  0 / 2  and the time synchronization information inserting method and the multiplexing method are recorded in a user application field of a FIG.  0 / 13  for transmission via the FIC. A recording method used for the video service encoding parameters will be described in detail later. 
     The video service encoding parameters are video service related information used for the DAB receiver to receive and process the video service. The video service encoding parameters are required for initializing a decoder and a demultiplexer. In other words, it is necessary to previously recognize whether the stream mode data included in the MSC corresponds to the video service, recognize encoding methods used for each of the audio stream, the video stream, and the additional data stream of the video service, and recognize the error resiliency method. 
     In brief, the video service encoding parameters include not only information regarding encoding, synchronization, and packetization of the video stream of the video service but also information required for initialization of a video decoder of the DAB receiver. In addition, the video service encoding parameters include not only information regarding encoding, synchronization, and packetization of the audio stream of the video service but also information required for initialization of an audio decoder of the DAB receiver. In the stream mode used to provide the video service, the start and the end of data are not designated. As a result, among continuously input packets, the start of data should be recognized. In the case of an MPEG-2 TS, a start point can be recognized by searching for a sync pattern beginning with 0×47. In other cases, a predetermined pattern is designated as a sync pattern and the sync pattern is determined to indicate the start of data. The end of data can be recognized by adding a packet number of a corresponding packet or information regarding whether the corresponding packet is the last packet to the rear of the sync pattern. The video service encoding parameters also include information such as the PID, program attribute table (PAT), program map table (PMT) of each of the audio stream, the video stream, and the additional data stream of the video service for demultiplexing of the multiplexed TS. 
     Although video service data is generated and transmitted based on MPEG-2 TS packets in  FIG. 5 , it may also be provided using IP packets as in  FIG. 6 . 
       FIG. 6  is a detailed block diagram of the video service encoder  110  for providing a video service, in which video service data is configured with IP packets according to an exemplary embodiment of the present invention. 
     The configurations and functions of the video encoder  502 , the audio encoder  504 , and the additional data encoder  506  have been already described with reference to  FIG. 5 . 
     A real-time transport protocol (RTP) packetizer  610  packetizes each of the encoded video stream, the encoded audio stream, and the encoded additional data stream into RTP packets using an RFC among various RTP packetization methods; If RTP packetization is used, payload types of an audio RTP packet and a video RTP packet are recorded in an RTP header and the RTP header is output as a video service encoding parameter. The audio RTP packet, the video RTP packet, and an additional data RTP packet are input to a UDP packet configuring unit  620  and an IP packet configuring unit  630 . The UDP packet configuring unit  620  generates a UDP packet by adding a UDP header to the input RTP packet and the IP packet configuring unit  630  generates an IP packet by adding an IP header to the generated UDP packet. 
     The generated IP packet is input to the error resiliency processing unit  640  to handle transmission errors. Since the IP packet generally has a variable length, the packet length of the IP packet should be changed to have a fixed length like an MPEG-2 TS packet to allow the use of the error resiliency method applied to MPEG-2 TS packets. Thus, the IP packet is sliced to have the same form as the MPEG-2 TS packet. After 188 bytes are formed using synchronization data or payload data or the IP packet is multiplexed using conventional MPEG-2 TS multiplexing, the 188 bytes or the IP packet is input to the error resiliency processing unit  640  for addition of the error correction data. The error correction coding method and the interleaving method are output as the video service encoding parameters. 
     Such an error-resilient TS processed by the error resiliency processing unit  640  is transmitted by the MSC multiplexer  140  over the MSC of DAB. 
     The parameterized information is in the form of video service encoding parameters that are input to a video service control unit  650 . The video service control unit  650  transmits the video service encoding parameters to a FIC processing unit  660  for transmission over the FIC, and the FIC processing unit  660  codes the video service encoding parameters and transmits the coded video service encoding parameters over the FIC. Among the received video service encoding parameters, encoding information of the video signal and the audio signal is recorded as a profile in the FIC. The error correction coding method and the interleaving method used in the error resiliency processing unit  640  are recorded in a DSCTy field of a FIG.  0 / 2  and the packetization information used in the RTP packetizer  610  is recorded in a user application field of a FIG.  0 / 13  for transmission via the FIC. 
       FIG. 7  illustrates the structure of an MPEG-2 TS packet generated by inserting synchronization data and error correction data according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 7 , a 188-byte MPEG-2 TS packet is formed using synchronization data  710  and payload data  720  and error correction data  730  that is generated using an error correction encoding method, such as Reed-Solomon coding, is added to the MPEG-2 TS packet. 
       FIG. 8  illustrates the structure of a FIB according to an exemplary embodiment of the present invention. 
     The FIB, a plurality of which are included in a FIC, includes a FIB data field  810  and a CRC field  820 . The FIB data field  810  is composed of 30 bytes and includes FIGs. When the FIB data field  810  cannot be completely filled up with FIG data, an end marker  830  is inserted to inform the DAB receiver that there is no further FIG data and channel data  840  is padded, thereby forming a 256-bit FIB. The end marker  830  may be, for example, “ 111   11111 ”. In each of the FIGs, a FIG type field  850  indicating the type of data included in a FIG data field  870  and a length field  860  indicating the length of the FIG data field  870  are inserted in a FIG header and actual data is included in the FIG data field  870 . FIG type information or syntax information of the actual data varies with an application used or information to be informed. Hereinafter, formats of FIG types related to service processing according to exemplary embodiments of the present invention will be described. 
       FIG. 9  illustrates the structure of a FIG type  0  according to an exemplary embodiment of the present invention. 
     The FIG type  0  contains information regarding the structures of current and future multiplex configuration, multiplex re-configuration, time and data, and other basic service information. A FIG type  0  field  910  includes various kinds of information according to the extension of the FIG type  0 . 
       FIG. 10  illustrates the structure of a FIG type  0 , extension  2  (i.e., FIG.  0 / 2 ) according to an exemplary embodiment of the present invention.  FIG. 10  illustrates a detailed structure of the FIG type  0  field  910  of  FIG. 9 , for extension  2 . The FIG.  0 / 2  contains information regarding service components. A description of a service is contained in a service field k (k is an integer). 
     A transport mechanism identifier (TMId) field  1010  indicates that a service component is a stream mode data service when a TMId is  01 . A DSCTy field  1020  should be newly defined for a video service using the stream mode. In an exemplary embodiment of the present invention, the application of the error resiliency method is recorded in the DSCTy field  1020 . For example, if a Reed-Solomon error correction coding method RS ( 204 , 188 ) and a convolutional interleaving method (12×17) are used in the stream mode for the video service and a Reed-Solomon error correction coding method RS( 208 , 192 ) and a block interleaving method are used in the packet mode for the multimedia service, the following application is suitable for allowing the DAB receiver to distinguish such uses. 
     DSCTy: value nnnnnn: stream mode for video service (RS( 204 , 188 ), CI(12×17)) 
     DSCTy: value mmmmmm: packet mode for multimedia service (RS( 208 , 192 ), blocking interleaving) 
       FIG. 11A  illustrates a detailed structure of a user application field of a FIG type  0 , extension  13  (i.e., FIG.  0 / 13 ) according to an exemplary embodiment of the present invention. 
     The FIG.  0 / 13  records data required for a service decoder of the DAB receiver. Among fields of the FIG.  0 / 13 , a user application type field  1110  indicates a user application module to be used to decode data corresponding to a service ID (SId). In the case of a video service using the stream mode, the user application type field  1110  may be defined as the video service. 
     A user application data field  1120  includes information regarding the encoding method, the packetization method, and the multiplexing method used for the video service and information regarding a user program type for each packet mode defined in the DAB standard when packet mode data such as character information, traffic information, still images, and web information are used as additional data. The video service encoding parameters having a format as illustrated in  FIG. 12  are recorded in the user application data field  1120 . 
     The video service encoding parameters may be recorded by newly defining an extension of the FIG type  0 . In this case, the user application field is generated as illustrated in  FIG. 11B . 
       FIG. 11B  illustrates the structure of a newly defined FIG for the video service encoding parameters according to an exemplary embodiment of the present invention. 
     A 16-bit service ID (SId) is recorded in the first portion of the user application field and video service encoding parameters having a format as illustrated in  FIG. 12  are recorded after the service ID, thereby implementing a FIG for video service encoding parameters. 
       FIG. 12  illustrates a data structure including video service encoding parameter information and packetization information including profile information and other information according to an exemplary embodiment of the present invention. 
     The video service encoding parameter information and the packetization information includes a profile ID and packetization information for the video stream and the audio stream. Hereinafter, the profile ID will be described in detail. For example, when MPEG-4 Advanced Video Coding (AVC) is used for video encoding, MPEG-4 Bit Sliced Arithmetic Coding (BSAC) is used for audio encoding, and an MEPG-2 TS using an MPEG-4 sync layer (SL) is used for packetization and multiplexing, an index 0×00 of Table 1 recorded as a profile is recorded in a profile ID field, instead of recording each of packetization and multiplexing methods used for the video stream and the audio stream in the user application data field. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Profile 
                 Profile 
                   
                   
                   
               
               
                 ID 
                 description 
                 Video codec 
                 Audio codec 
                 Muxing/packet 
               
               
                   
               
             
            
               
                 0x00 
                 Video service 1 
                 MPEG-4 
                 MPEG-4 
                 MPEG-2 TS 
               
               
                   
                   
                 AVC 
                 BSAC 
                 with MPEG-4 
               
               
                   
                   
                   
                   
                 SL 
               
               
                 0x01 
                 Video service 2 
                 MPEG-4 
                 MPEG-4 
                 MPEG-2 TS 
               
               
                   
                   
                 AVC 
                 AAC 
                 with MPEG-4 
               
               
                   
                   
                   
                   
                 SL 
               
               
                 0x02 
                 Video service 3 
                 MPEG-4 
                 MPEG-4 
                 MPEG-2 TS 
               
               
                   
                   
                 AVC 
                 AAC 
                 with MPEG-2 
               
               
                   
                   
                   
                   
                 PES 
               
               
                 0x03 
                 Video service 4 
                 MPEG-4 Part 2 
                 MPEG-2 
                 MPEG-2 TS 
               
               
                   
                   
                   
                 AAC 
                 with MPEG-2 
               
               
                   
                   
                   
                   
                 PES 
               
               
                   
               
            
           
         
       
     
     The video service encoding parameter information may be included in a FIG.  0 / 8  and a FIG.  0 / 13  among FIGs, but the video service control unit of the DAB receiver processes the video service using the video service encoding parameter information. 
     The profile information and other information may be assigned to separate FIGs to record the video service encoding parameter information and the packetization information in at least two different FIGs. The profile information and other information may also be provided as essential information when an electronic program guide (EPG) is provided during broadcasting. Thus, by analyzing the video service encoding parameter information and the packetization information of the video service, it is possible to previously determine whether a provided service can be processed by the DAB receiver. 
     By recording the type of a video service, such as a news program or an educational program, together with the profile ID, in the user application data field, the DAB receiver can classify received video services according to their types and may provide information regarding the types of the video services to a user as additional information. For example, when the user wishes to watch a news program among the received video services, only programs corresponding to the news program among the received video services may be listed through information received via the FIC. 
       FIG. 13  illustrates a frame structure according to an exemplary embodiment of the present invention. As illustrated in  FIG. 13 , the type of a video service, e.g., the type of a provided program, is specified by a 5-bit field following a profile ID field. To this end, the 5-bit field as illustrated in  FIG. 13  or a predetermined-length field may be used. 
       FIG. 14  illustrates a program type code table used in an exemplary embodiment of the present invention. When the 5-bit field is used, values in a table of ETSI TS 101 756 used in a standard of the European Telecommunications Standards Institute (ETSI) may be used as illustrated in  FIG. 14 . As such, by using a conventional DAB program type table as a table for specifying programs of video/audio services, more efficient use of a memory of the DAB receiver is possible. A separate program type table for a video service may also be defined. 
       FIG. 15  is a block diagram of a receiver that receives a video service in a DAB system according to an exemplary embodiment of the present invention. 
     The receiver receives an OFDM modulated signal through a tuner  1510  and demodulates the OFDM modulated signal through an OFDM demodulator  1520 , thereby generating a DAB transmission frame. 
     A channel decoder  1530  includes a baseband decoder  1532  and an OFDM channel decoder  1534 . The channel decoder  1530  parses FIC data to generate a service list and shows the service list to the user. 
     The FIC data includes the video service encoding parameter information and the packetization information, and thus, an analysis of the FIC data can provide the type of a provided service and the encoding method and packetization method used for data of the provided service. 
     The FIC data also includes program type information that specifies the type of a provided video service. The channel decoder  1530  can recognize the type of a provided video service by analyzing the program type information of the FIC data. 
     A control unit  1580  transmits the type of a video service analyzed by the channel decoder  1530  to an additional data decoder  1570  to show the analyzed type to the user through a display unit (not shown) of the receiver. 
     If the user selects a service, an MSC demultiplexer  1540  extracts and outputs service data corresponding to the selected service. If the user selects a video service, an encoded video stream, an encoded audio stream, and an encoded additional data stream of the selected video service are transmitted to a video decoder  1550 , an audio decoder  1560 , and an additional data decoder  1570  for decoding. 
     The control unit  1580  controls functional components according to the video service encoding parameter information and the packetization information. 
       FIG. 16  is a detailed block diagram of the video service control unit  550  according to an exemplary embodiment of the present invention. 
     The video service control unit  550  includes a service information analyzing unit  1610 , a video service encoding information analyzing unit  1620 , and a video service decoder driving unit  1630 . 
     The service information analyzing unit  1610  analyzes the FIG.  0 / 2  of  FIG. 10  to show a provided service to the user and analyzes information regarding sub-channels and service components related to a video service selected by the user. 
     The video service encoding information analyzing unit  1620  analyzes the error resiliency method of the video service through the DSCTy of the FIG.  0 / 2  and the video service decoding method used for the video service through the user application type and user application data of the FIG  0 / 13 . The video service decoder driving unit  1630  drives the video service decoder including the error resiliency processing unit based on video service encoding information recognized through the analysis. 
       FIGS. 17A and 17B  are flowcharts illustrating a method of providing a video service with reference to video service encoding information and packet configuration information in a stream mode of DAB, according to an exemplary embodiment of the present invention. 
     Encoded audio data, video data, and additional data, which are related to a video service, are received from outside or audio data and video data encoded by an audio encoder and a video encoder included in a video service encoder are transmitted in operation S 1710 . Time synchronization information is inserted and a video service stream is multiplexed to smoothly provide the video service in operation SI  720 . Error correction data is added and convolutional interleaving is performed through an error-resiliency processing unit in operation S 1730 . After the error-resilient stream is channel-coded in operation S 1740 , the stream is multiplexed in operation S 1750 , recorded in an MSC in operation S 1760 . The stream is then recorded in a DAB transmission frame together with a FIC, which includes video service encoding parameters, for transmission in operation S 1765 . 
     Video service encoding parameter information and packet configuration information are received in operation S 1770 , recorded in a FIG field in operation S 1780 , and inserted into the FIC in operation S 1790 . In other words, information used for a DAB receiver to smoothly process a provided video service is inserted into the FIC, instead of the MSC that is a service data channel. The FIC is composed of FIBs, each of which includes several FIGs. In an exemplary embodiment of the present invention, fields are changed and newly defined in FIG.  0 / 8  and FIG.  0 / 13 . The video service encoding parameter information and the packet configuration information are included in the newly defined fields of FIG.  0 / 8  and FIG.  0 / 13 . The video service encoding parameter information is multiplexed with the MSC, thereby generating the DAB transmission frame in operation S 1795 . The structures of the FIG.  0 / 8  and the FIG.  0 / 13  have already been described above. 
     In operation S 1795 , program type information indicating the type of the provided video service, provided together with the program ID in the user application data field of the FIG, may also be multiplexed with the MSC, thereby generating the DAB transmission frame. 
       FIG. 18  is a flowchart illustrating a method of receiving a video service with reference to video service encoding information and packet configuration information in a DAB receiver according to an exemplary embodiment of the present invention. 
     A DAB transmission frame is received in operation S 1805  and information regarding sub-channels and service components related to a service selected by a user is analyzed in operation S 1810 . 
     The FIG.  0 / 8  and the FIG.  0 / 13  in the FIC that is different from the service data channel are analyzed in operation S 1815 . The video service encoding parameter information and the packet configuration information required for processing the selected video service are recognized in operation S 1820 . 
     Program type information indicating the type of the provided video service is analyzed and the analyzed program type information is provided to the user in operation SI  825 . 
     Driving of the video service decoder is initialized based on the analyzed information in operation SI  830 . 
     The received DAB transmission frame is demultiplexed in operation S 1835  and channel-decoding and error-resiliency decoding are performed on sub-channel data of the MSC in operation S 1840 . The video service stream is demultiplexed in operation S 1845 . Time synchronization information is extracted through depacketization and audio data and video data are decoded by the audio decoder and the video decoder in operation SI  850 . The decoded data is output as video service components according to the extracted time synchronization information in operation SI  855 . 
     Additional data including packet mode data, such as character information, traffic information, still images, and web information, is also decoded or depacketized by an initialized additional data decoder according to the video service encoding parameter information and the packetization information. 
     Hereinafter, another exemplary embodiment of the present invention will be described with reference to  FIGS. 19 and 20 .  FIG. 19  illustrates a frame structure according to an exemplary embodiment of the present invention.  FIG. 20  is a flowchart illustrating a method of receiving a video service in a DAB receiver according to an exemplary embodiment of the present invention. 
     A service having contents for audio data and video data in which the audio data is actually serviced as a main component and the video data is used as additional information may also be configured as a video service. Thus, additional broadcasting information indicating whether contents of a program of the video service use audio data or video data as the main component may be used to allow the user to selectively play the provided video service. 
     To this end, information indicating whether the main component of the video service is video data or audio data is included in a main contents information field following the profile ID in a user application data field as illustrated in  FIG. 19 . For example, the main contents information field having a value of 0 may indicate that a currently received video service is video broadcasting that uses video data as the main component. Conversely, the main contents information field having a value of 1 may indicate that the received video service is audio broadcasting that uses audio data as the main component. 
     Thus, even if a video service stream received by the DAB receiver includes an audio stream, a video stream, and a data stream, when broadcasting uses audio data as the main component, it is classified as audio data. Thus, only the broadcasting audio data may be decoded by an audio decoder specified by the profile ID and broadcasting video data may be selectively decoded according to a user&#39;s selection. In this way, the amount of computation for data decoding in the DAB receiver can be reduced. 
     Referring to  FIG. 20 , a DAB transmission frame is received in operation S 2005 , and information regarding sub-channels and service components related to a service selected by the user is analyzed in operation S 2010 . 
     The FIG.  0 / 8  and the FIG.  0 / 13  in the FIC that is different from the service data channel are analyzed in operation S 2015 . The video service encoding parameter information and the packet configuration information required for processing the selected video service are recognized in operation S 2020 . 
     Main contents information indicating the type of the provided video service is analyzed and the analyzed main contents information is provided to the user in operation S 2025 . 
     Driving of the video service decoder is initialized based on the analyzed information in operation S 2030 . 
     The received DAB transmission frame is demultiplexed in operation S 2035 . Channel-decoding and error-resiliency decoding are performed on sub-channel data of the MSC in operation S 2040 . The video service stream is demultiplexed in operation S 2045 . 
     In operation S 2050 , it is determined whether main contents information analyzed in operation S 2025  indicates audio data or video data. 
     When the main component of the provided video service is audio data, only audio data of the provided video service is decoded by an audio decoder specified by the profile ID in operation S 2060 . The decoded audio data is output as components of the video service according to the extracted time synchronization information in operation S 2065 . 
     When the main component of the provided video service is video data, audio data and video are decoded in operation S 2070 . Next, the decoded data is output as components of the video service according to the extracted time synchronization information in operation S 2075 . 
     When the main component of the provided video service are audio data, decoding may be performed on both audio data and video data according to user&#39;s selection and the decoded data may be output as components of the video service according to the extracted time synchronization information. 
     As described above, according to an exemplary embodiment of the present invention, by transmitting program type information together with profile ID information over a FIC, a user of a DAB receiver can easily search for and select a program of a desired type and can be provided with a desired service. 
     Since information specifying a main component of a video service is transmitted over a FIC, the decoding efficiency of the DAB receiver can be improved and the user can make a selection with respect to the provided video service within a wide selection range. 
     Meanwhile, the method of controlling a video service including video service encoding parameter information and packetization information according to an exemplary embodiment of the present invention can also be embodied as computer program on a computer-readable recording medium. Code and code segments of the computer program can be easily construed by computer programmers in the art. The program is stored in the computer-readable recording medium, and read and executed by a computer, thereby implementing the method of controlling the video service. Examples of the computer-readable recording medium include magnetic recording media, optical recording media, and carrier waves. 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.