Abstract:
Disclosed is a digital broadcast receiving apparatus and a method thereof. The digital broadcast receiving apparatus includes a memory unit for storing packet IDs corresponding to broadcasting channels, a program changing unit for reading the packet ID corresponding the next broadcasting channel from the memory unit, a transport channel processing unit for deinterleaving a transport channel corresponding to the read packet ID, and a buffering unit including a first buffer for buffering transport channel data output from the transport channel processing unit and a second buffer for outputting data of another transport channel of which a buffering is completed.

Description:
PRIORITY  
       [0001]     This application claims priority to an application entitled “Digital Multimedia Broadcast Receiving Apparatus and Method Thereof” filed in the Korean Industrial Property Office on Aug. 27, 2004 and assigned Serial No. 2004-67859, the contents of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a digital multimedia broadcasting channel selection apparatus and a method thereof.  
         [0004]     2. Description of the Related Art  
         [0005]     With the development of digital broadcasting technology and mobile communication technology, digital broadcasting services that enable users to view digital multimedia broadcasts even while the user is in motion is an increasing matter of concern. Digital multimedia broadcasting (hereinafter referred to as a “DMB”) is a broadcasting service that makes it possible for a user to view diverse multimedia broadcasts through multiple channels or a personal portable receiver, or a receiver for vehicles having a non-directional receiving antenna, even while the user is in motion. Particularly, a satellite DMB adopted in Korea uses CDM (Code Division Multiplexing) technology that is similar to the CDMA mobile technology of the Standard Rec. BO.1130-4: System-E of ITU (International Telecommunication Union).  
         [0006]     The DMB system receives five channels in order to provide one broadcasting service to a specified terminal. These five channels will be explained in detail with reference to  FIG. 1 .  
         [0007]      FIG. 1  is a diagram illustrating the channels provided through a broadcasting service in a DMB system.  
         [0008]     As illustrated in  FIG. 1 , in the DMB system, the broadcasting service is provided through a plurality of CDM transport channels. The CDM transport channels may be a channel ‘ 0 ’  100  for transmitting pilot information, a channel ‘ 1 ’  102  for transmitting an EPG (Electronic Program Guide) information, a channel ‘ 2 ’  104  for transmitting CAS (Conditional Access System) information, and M transport channels for transmitting a broadcast traffic. For example, an AV (Audio/Video) broadcasting channel signal is transmitted through a channel ‘ 3 ’  106  of a broadcast ‘A- 1 ’, a channel ‘ 4 ’  108  of a broadcast ‘A- 2 ’ and a channel ‘N’  110  of a broadcast ‘A-M’. The video broadcasting channel of the AV broadcasting channel is composed of two CDM channels, and the audio broadcasting channel thereof is composed of one CDM channel.  
         [0009]     In the DMB system, the receiving apparatus needs to change a PID (Packet Identification) corresponding to a broadcasting channel subject to selection and open a CDM channel that interworks with the PID when it selects the AV broadcasting channel. The receiving apparatus fills buffers of a deinterleaver for the changed broadcasting channel, and then displays the changed broadcasting channel. It takes time to fill and empty the deinterleaver buffers whenever the broadcasting channel is changed. Specifically, it takes about 3 to 4 seconds in addition to the time required for filling the buffers for storing an AV stream, so that a user needs to wait for a long time whenever the broadcasting channel is changed.  
         [0010]     An automatic channel selection method is an important function for seeking convenience in use, and has been used in a terminal that receives analog FM/AM audio broadcasts. The automatic channel selection method provides the corresponding channel service to the user as it changes the broadcasting channels.  
       SUMMARY OF THE INVENTION  
       [0011]     As described above, if the automatic channel selection method is applied to the DMB receiving apparatus, a time for filling the deinterleaver buffers is required whenever the CDM channel is changed, and this time is added to a time for filling the buffers for storing the AV stream, so that the user is required to wait whenever the channel is selected.  
         [0012]     Accordingly, the present invention has been designed to solve at least the above problems occurring in the prior art, and provides a digital multimedia broadcasting channel selection apparatus and a method thereof that can automatically select channels in a digital broadcast receiving apparatus.  
         [0013]     The present invention also provides a digital multimedia broadcasting channel selection apparatus and a method thereof that can reduce the waiting time required for channel selection during an automatic channel selection operation in a digital broadcast receiving apparatus.  
         [0014]     In one embodiment of the present invention, there is provided a digital broadcast receiving apparatus which includes a memory unit for storing packet IDs corresponding to broadcasting channels, a program changing unit for reading from the memory unit the packet ID corresponding the next broadcasting channel, a transport channel processing unit for deinterleaving a transport channel corresponding to the read packet ID, and a buffering unit including a first buffer for buffering transport channel data output from the transport channel processing unit and a second-buffer for outputting data of a second transport channel. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0016]      FIG. 1  is a diagram illustrating channels provided through a broadcasting service in a DMB system;  
         [0017]      FIG. 2  is a block diagram illustrating the construction of a satellite DMB broadcast receiving apparatus according to an embodiment of the present invention;  
         [0018]      FIG. 3  is a diagram illustrating an output state of an AV broadcasting channel during a channel selection in a DMB receiving apparatus according to an embodiment of the present invention; and  
         [0019]      FIG. 4  is a flowchart illustrating a control operation of a DMB receiving apparatus according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Preferred embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings. In the following description of the present invention, only the elements necessary for understanding the operation of the present invention will be explained, and a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.  
         [0021]     The present invention provides a method for minimizing the waiting time for a channel selection during the viewing of broadcasting channel information if a next broadcasting channel during an automatic channel selection operation. In order to apply the automatic channel selection to a DMB broadcasting, PID values corresponding to respective broadcasting channels are automatically changed, in succession or in a specified order, through a UI (User Interface).  
         [0022]     In order to apply the present invention to a video channel, at least four CDM channels for an AV stream should be open. However, if an audio channel is selected, only two open CDM channels will suffice for the audio channel signal. The principle of an automatic audio channel selection according to the embodiment of the present invention will be explained.  
         [0023]      FIG. 2  is a block diagram illustrating the construction of a DMB broadcast receiving apparatus according to an embodiment of the present invention.  
         [0024]     Referring to  FIG. 2 , the DMB broadcast receiving apparatus  200  according to an embodiment of the present invention includes a CDM selection unit  210  for selecting a CDM channel corresponding to a PID (Packet Identification), a CDM channel processing unit  220  for deinterleaving a specified CDM channel according to a CDM selection signal from the CDM selection unit  210 , a buffering unit  230  for buffering respective deinterleaved CDM transport channels, a merging unit  240  for generating a broadcasting channel stream by merging data from the buffered CDM channels, and a TS (Transport Stream) demultiplexer  250  for demultiplexing the input broadcasting channel stream. The DMB broadcast receiving apparatus  200  further includes a codec  270  for converting a digital signal into an audio signal or a video signal.  
         [0025]     Additionally, the DMB broadcast receiving apparatus  200  includes a PID change unit  260  for outputting PID values corresponding to the selected broadcasting channels of an automatic channel selection as requested by a user or by a specified condition.  
         [0026]     The number of CDM channels that can be decoded by the DMB receiving apparatus is less than the total number of CDM channels provided in the DMB system. For example, in the case of the present satellite DMB system, data is transmitted through 29 CDM transport channels, and the DMB receiving apparatus is constructed to process 5 CDM transport channels. Accordingly, the DMB receiving apparatus essentially receives a channel for transmitting pilot information, a channel for transmitting EPG (Electronic Program Guide) information and a channel for transmitting a CAS (Conditional Access System) information. In addition, the DMB receiving apparatus receives two CDM transport channels for transmitting an actual AV stream. A satellite DMB receiving apparatus may be constructed to process five or more CDM transport channels and the present invention can be applied to such a DMB receiving apparatus.  
         [0027]     Referring to  FIG. 2 , if an automatic channel selection is requested by a user or by a specified condition, the PID change unit  260  provides the PID values corresponding to the CDM transport channels to the CDM selection unit  210 . The PID change unit  260  may be connected to a user interface that can receive a user&#39;s selection of a specified broadcasting channel. Also, the PID change unit  260  may be connected to a specified memory (not illustrated) that stores the broadcasting channels to be automatically selected and the corresponding PIDs. In this case, the PID change unit  260  outputs the PID values at predetermined intervals to match a buffering time of the buffering unit  230 .  
         [0028]     The CDM selection unit  210  receives the PID corresponding to the next broadcasting channel from the PID change unit  260 , and instructs the CDM channel processing unit  220  to receive the corresponding CDM channel. The CDM channel processing unit  220  obtains the CDM transport channel corresponding to the PID from among the CDM transport channels broadcast from the DMB system and deinterleaves the obtained CDM transport channel. Then, the CDM channel processing unit  220  outputs the deinterleaved transport channel data to the buffering unit  230 . The buffering unit  230  includes a plurality of buffers  231  to  239  and stores the transport channel data output from the CDM channel processing unit  220 . The plurality of buffers  231  to  239  provide the buffered transport channel data to the merging unit  240 . The merging unit  240  generates a broadcasting channel stream to be output to the user from the transport channel data and outputs the generated broadcasting channel stream to the TS demultiplexer  250 . The TS demultiplexer  250  divides the broadcasting channel stream by broadcasting channels and provides the divided broadcasting channel stream to the codec  270 . The codec  270  converts the broadcasting channel data provided from the TS demultiplexer  250  into an audio signal or video signal.  
         [0029]     The output state of the AV broadcasting channel during the automatic channel selection operation of the DMB broadcast receiving apparatus  200  will be explained with reference to  FIG. 3 .  
         [0030]      FIG. 3  is a diagram illustrating the output state of the AV broadcasting channel during the channel selection operation of the DMB receiving apparatus according to an embodiment of the present invention.  
         [0031]     Referring to  FIG. 3 , the DMB receiving apparatus  200  according to the present invention buffers a stream ‘A’ and a stream ‘B’, for example, in a period prior to a period  70  according to a set order during the automatic channel selection operation. Then, the DMB receiving apparatus  200  outputs the stream ‘A’ to the user according to the order of the automatic channel selection in the period  70 . After the lapse of a set time, the DMB receiving apparatus  200  outputs the buffered stream ‘B’ to the user in a period  71 . At this time, the DMB receiving apparatus  200  receives the CDM channel of the next broadcasting channel, and buffers a stream ‘C’ corresponding to the next broadcasting channel. Similarly, the DMB receiving apparatus  200  buffers a stream ‘D’ corresponding to the next broadcasting channel by receiving the CDM channel of the next broadcasting channel as it outputs the buffered stream ‘C’ to the user in a period  72 . In the embodiment of the present invention as described above, the streams ‘A’, ‘B’, ‘C’ and ‘D’ are output according to the type AV broadcasting channel. That is, in the case of the video channel, the respective streams are output through two CDM channels and in the case of the audio channel, the respective streams are output through one CDM channel.  
         [0032]     The DMB receiving apparatus  200  according to the present invention stores information about the CDM channels. Accordingly, the DMB receiving apparatus  200  minimizes the waiting time for the channel selection that the user feels by receiving the CDM channels of the broadcasting channels in a set order during the automatic channel selection operation.  
         [0033]     The operation of the DMB receiving apparatus  200  will be explained with reference to  FIG. 4 .  
         [0034]      FIG. 4  is a flowchart illustrating the control operation of the DMB receiving apparatus according to an embodiment of the present invention.  
         [0035]     Referring to  FIG. 4 , the DMB receiving apparatus determines whether or not the automatic channel selection is requested by the user or by a specified condition at step  310 . The specified condition may be a condition that the time for the automatic channel selection set by the user in advance arrives. If the automatic channel selection is requested, the DMB receiving apparatus  200  buffers the initial broadcasting stream by confirming the PID value corresponding to the set broadcasting channel to be selected in succession and receiving the corresponding CDM channels at step  320 . Then, the DMB receiving apparatus  200  outputs the broadcasting stream buffered for a predetermined amount of time at step  330 . Simultaneously, the DMB receiving apparatus  200  buffers the corresponding broadcasting stream by obtaining the PID value corresponding to the set broadcasting channel to be output in succession to the broadcasting stream presently output at step  340 .  
         [0036]     Then, the DMB receiving apparatus  200  determines if the presently output broadcasting stream is selected by the user at step  350 . If the presently output broadcasting stream is selected by the user, the DMB receiving apparatus  200  proceeds to step  370  to stop the automatic channel selection operation.  
         [0037]     If the presently output broadcasting stream is not selected by the user, the DMB receiving apparatus  200  proceeds to step  360 , and outputs the next broadcast buffered for the set amount of time. Then, the DMB receiving apparatus  200  judges whether the automatic channel selection function is terminated by the user at step  380 .  
         [0038]     If the automatic channel selection function is not terminated by the user, the DMB receiving apparatus  200  returns to the step  340 , and buffers the corresponding broadcasting stream by obtaining the PID value of the next broadcasting channel to be outputted and receiving the corresponding CDM channel.  
         [0039]     As described above, the DMB receiving apparatus according to the present invention can minimize the waiting time for the channel selection by receiving CDM channels of the broadcasting channels in the set order and buffering the next broadcasting stream during the automatic channel selection.  
         [0040]     While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled 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 appended claims.