Patent Publication Number: US-2010119216-A1

Title: Broadcast data recording and reproducing method and apparatus for mobile terminal

Description:
CLAIM OF PRIORITY 
     This application claims the benefit of the earlier filing date, pursuant to 35 USC 119, to that patent application entitled “BROADCAST DATA RECORDING AND REPRODUCING METHOD AND APPARATUS FOR MOBILE TERMINAL” filed in the Korean Intellectual Property Office on Nov. 12, 2008 and assigned Serial No. 10-2008-0112400, the contents of which are  10  incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mobile terminal and, in particular, to a broadcast data recording and reproducing method and apparatus for a mobile terminal that is capable of improving digital broadcast playback performance of the mobile terminal by decoding broadcast data using previously stored Packet Identifiers (PID&#39;s). 
     2. Description of the Related Art 
     Digital broadcast playback is one of the most popular functions of the latest generation mobile terminals. A broadcast-enabled mobile terminal has a capability to demodulate and decode a digitally encoded and modulated broadcast signal in a specific digital broadcast format. 
     There are several mobile digital broadcast formats including Digital Multimedia Broadcasting (DMB), Digital Video Broadcasting-Handheld (DVB-H), Integrated Service Digital Broadcasting-Terrestrial (ISDB-T) and MediaFlO. In the mobile digital broadcast systems, the broadcast data are broadcasted in the form of a packet stream. In order for the mobile terminal to receive and play the broadcast data, the mobile terminal has to extract the packet identifier (PID) from a Program Map Table (PMT) acquired from the broadcast data. That is, the mobile terminal acquires the video packet identifier, audio packet identifier, and data packet identifier and decodes the Packetized Elementary Streams (PES&#39;s) based on the identifiers. However, when playing back the recorded broadcast data, the mobile terminal cannot decode the broadcast data received with the packets before acquiring the PMT normally, since there is no PID&#39;s of those packets. 
     Accordingly, the packets received before acquiring the PMT from the broadcast data are useless and, thus, occupies the memory space of the mobile terminal unnecessarily especially when recoding the broadcast data. 
     SUMMARY OF THE INVENTION 
     In order to overcome the problem of the prior art, the present invention provides a broadcast data recording and reproducing method and apparatus for a broadcast-enabled mobile terminal that is capable of avoiding waste of memory space by storing the broadcast data with the PID&#39;s referred from the PMT. 
     Also, the present invention provides a broadcast data recording and reproducing method and apparatus for a broadcast-enabled mobile terminal that is capable of reducing playback start delay of recorded broadcast data by storing time information together with the chanced PID&#39;s, when the PID&#39;s are changed while recording the broadcast data. 
     In accordance with an exemplary embodiment of the present invention, a method for playing recorded broadcast data in a mobile terminal includes detecting a playback instruction for playing recorded broadcast data; determining whether a resume marker exists in the recorded broadcast data; obtaining, when a resume marker exists, a resume time for determining a playback start time of the recorded broadcast data; extracting a system time of the recorded broadcast data corresponding to the obtained resume time; acquiring a plurality of packet identifiers corresponding to the system time; and decoding the recorded broadcast data indicated by the acquired packet identifier. 
     In accordance with another exemplary embodiment of the present invention, a broadcast data recording method for a mobile terminal includes playing broadcast data received in real time; acquiring Program Map Tables (PMT&#39;s) from the broadcast data; extracting packet identifiers from the PMT&#39;s; starting the recording of the broadcast data in response to a recording instruction input by a user; and storing the packet identifiers and system times at which the packet identifiers are extracted. 
     In accordance with another exemplary embodiment of the present invention, a broadcast data recording and reproducing apparatus for a mobile terminal includes a storage unit which stores packet identifiers extracted from broadcast data and system times; and a control unit which obtains, when a resume marker exists, a resume time pointed to by the resume marker in response to a recorded broadcast data playback instruction, extracts a plurality of packet identifiers stored in correspondence with the resume time, and plays the recorded broadcast data using the packet identifiers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above features and advantages of the present invention will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic block diagram illustrating a configuration of a mobile terminal according to an exemplary embodiment of the present invention; 
         FIG. 2  is a flowchart illustrating a method for recording and reproducing broadcast data according to an exemplary embodiment of the present invention; 
         FIG. 3  is a flowchart illustrating a broadcast data recording procedure of a broadcast data playback method for a mobile terminal according to an exemplary embodiment of the present invention; 
         FIGS. 4   a  to  4   c  represent tables illustrating exemplary packet identifier information for used in the broadcast data recording method according to an exemplary embodiment of the present invention; 
         FIG. 5  is a flowchart illustrating a recorded broadcast data playback procedure of a broadcast data playback method for a mobile terminal according to an exemplary embodiment of the present invention; and 
         FIG. 6  is a conceptual diagram illustrating the recorded broadcast data playback timing in the broadcast data playback method of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Exemplary embodiments of the present invention are described with reference to the accompanying drawings in detail. For the purposes of clarity and simplicity, detailed descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present invention. Further, note that the same reference numbers are used throughout the drawings to refer to the same or like parts. 
     In an exemplary embodiment of the present invention, the term “system time” denotes a time recorded when the broadcast data recording is initially started or the PMT is changed during the recording. Here, the system time can be used for determining the playback restart time of the recorded broadcast data when a resume marker is used. The resume marker is a time point at which the recorded broadcast data playback is paused. 
     In an exemplary embodiment of the present invention, the term “resume time” denotes a time point at which the recorded broadcast data playback is paused. The resume time is acquired by extracting the system time using the conditional expression of equation  1 , which is described in detail later. The resume time can be expressed by means of the resume marker. 
     In an exemplary embodiment of the present invention, the mobile terminal can be one of a Personal Digital Assistant (PDA), a Smartphone, a dedicated digital broadcast receiver, and a mobile phone including Code Division Multiple Access (CDMA) terminal, Wideband CDMA (WCDMA) terminal, Global System for Mobile communications (GSM) terminal, Universal Mobile Telecommunication System (UMTS) terminal, and their equivalent devices that support recording and reproducing digital broadcast data. 
       FIG. 1  is a schematic block diagram illustrating a configuration of a mobile terminal according to an embodiment of the present invention. 
     As shown in  FIG. 1 , the mobile terminal according to the embodiment of the present invention includes a control unit  100 , an input unit  110 , a display unit  120 , a storage unit  130 , an audio processing unit  140 , a broadcast reception unit  150 , and a Radio Frequency (RF) unit  160 . 
     The input unit  110  is provided with a plurality of alphanumeric keys for receiving alphabetic and numeric information and a plurality of function keys for setting and executing the functions of the mobile terminal. The function keys can be implemented in the form of navigation keys, side keys, and shortcut keys. The input unit  110  generates key data in response to keystrokes and sends the key data to the control unit  100 . Particularly in an exemplary embodiment of the present invention, the input unit  110  is configured to generate and send a key command for recording broadcast data while the mobile terminal playing the broadcast data. In more detail, the input unit  110  generates a key command for recording the broadcast data in real time, a key command for selecting a program, and a key command for playing the recorded broadcast data. These key commands are sent to the control unit  100 . 
     The display unit  120  displays various screen images generated in association with the operations of the mobile terminal. For instance, the display unit  120  provides a visual interface to create a broadcast data playback screen image, an idle mode screen image, and various menu screen images. The display unit  120  can be implemented with a Liquid Crystal Display (LCD). In this case, the display unit  120  can be an LCD controller, a video data memory, and a plurality of LCD devices. In case when the LCD supports touchscreen functionality, the display unit  120  can act as a part of the input unit  110 . Particularly in an exemplary embodiment of the present invention, the display unit  120  can be configured to display the broadcast data decoded from the broadcast signal received by means of the broadcast reception unit  150 . The display unit  12  can display the video data of the recorded broadcast data with the resume marker function under the control of the control unit  100 . The display unit  120  also can provide a control interface for controlling the recording of the broadcast data. 
     The storage unit  130  stores application programs associated with the digital broadcast playback function according to an exemplary embodiment of the present invention. The storage unit  130  also provides a buffer for buffering the broadcast signals. The storage unit  130  can include a program region and a data region. 
     The program region stores an operating system (OS) for booting up the mobile terminal and application programs including a broadcast data reception application, a broadcast data recording application, a PID backup application for storing the PID&#39;s extracted from the PMT while recording the broadcast data, a system time recording application for recording the system time point at which the PMT is changed, and a resume marker application for checking the resume marker while playing the recorded broadcast data. The program region also loads the application programs in response to the user request under the control of the control unit  100 . 
     The data region stores the application data generated while the application programs are running in the mobile terminal. Particularly in an exemplary embodiment of the present invention, the data region stores the broadcast signal and broadcast data received by means of the broadcast reception unit  150 . The data region also stores the data associated with one or more supplementary functions of the mobile terminal such as phonebook data, audio data, other user data and metadata of the data. The data region also stores the PID&#39;s extracted while recording the broadcast data. The PID&#39;s includes video PID&#39;s, audio PID&#39;s, and data PID&#39;s and stores them in the form of a table. The data region also stores the time points at which the broadcast data recording is initialized and the PMT is changed during the broadcast data recording. 
     The audio processing unit  140  includes a speaker (SPK) for outputting the audio data received by means of the broadcast reception unit  150  and a microphone (MIC) for inputting audio signal including voice and other sound. Particularly in an exemplary embodiment of the present invention, the audio processing unit  140  can be configured to output an alert sound for alerting the start of the broadcast data recording. The audio processing unit  140  also can process the audio data extracted from the recorded broadcast data. 
     The broadcast reception unit  150  receives the broadcast data corresponding to a program selected by the user under the control of the control unit  100 . Particularly in an exemplary embodiment of the present invention, the broadcast reception unit  150  is provided with a receiver module (not shown) for receiving the broadcast signals transmitted by a broadcast station. In operation, the broadcast reception module  150  receives the broadcast signals transmitted by the broadcast station and sends the received broadcast signal to the control unit  100 . The receiver module is a device configured to process the broadcast signal format of the broadcast station. For instance, when the broadcast station transmits the broadcast signal in a DMB format, the broadcast reception unit  150  is preferably implemented with a DMB receiver module for receiving the broadcast signals normally. In case that the broadcast station transmits the broadcast signals in DVB-H format, the broadcast reception unit  150  should be implemented with a DVB-H receiver module for receiving the broadcast signals normally. In the DMB and DVB-H systems, the broadcast data are transmitted in the form of packet streams and each packet is composed of a header and a payload. The packet header includes PID that is used for packet synchronization and channel identification. 
     The RF unit  160  is responsible for establishing a radio communication channel with a base station for voice and data such that the mobile terminal communicates with another terminal attached to the base station or other network. The RF unit  160  can be configured to be maintained in an activate state while the mobile terminal receives the broadcast signal and such that, when an incoming call or message is detected, the control unit  100  processes the incoming call or message prior to the broadcast signal. The RF unit  160  can be composed of an RF transmitter for up-converting and amplifying the frequency of the transmission signal and an RF receiver for low-noise amplifying and down-converting the frequency of the received signal. 
     The control unit  100  controls general operations of the mobile terminal and signaling among the internal function blocks of the mobile terminal. Particularly in an exemplary embodiment of the present invention, the control unit  100  extracts Program Specific Information (PSI) from the broadcast signal received by means of the broadcast reception unit  150 . Here, the PSI includes a Program Association Table (PAT). The PAT includes the PMT information. The PMT information includes PID information. 
     The control unit  100  executes a broadcast data reception application in response to a user instruction input through the input unit  110  and displays the video data of the broadcast data received by means of the broadcast reception unit  150  on the display unit  120 . If a broadcast playback instruction is input through the input unit  110 , the control unit  100  acquires the PMT from the received broadcast data and extracts the packet data identifier information associated with the program from the PMT. The packet data identifier information includes at least one of a video packet identifier, an audio packet identifier, and a data packet identifier. 
     When a broadcast data recording instruction is input during the video data playback, the control unit  100  starts recording the broadcast data. During the broadcast data recording, the control unit  100  performs backup on the packet identifier information extracted from the PMT. The packet identifier information can be extracted from the PMT acquired while playing the broadcast data. At this time, the control unit  100  checks the current system time and stores the information on current system time within the storage unit  130  together with the packet identifier information extracted from the PMT. 
     The control unit  100  compares the PMT&#39;s acquired from the broadcast data that are received and recorded and monitors to detect a change of the PMT. If a PMT change is detected, the control unit  100  extracts the PID&#39;s of the changed PMT and checks the current system time. The system time can be a local time of the mobile terminal and represents a time point at which the broadcast data recording starts or a PMT change is detected or when the resume marker function is used in playback of the recorded broadcast data. The resume marker function is used for extracting the system time corresponding to the resume time of the playback of the recorded broadcast data and decoding the recorded broadcast data from the resume time with reference to the packet identifier information. 
     The control unit  100  can control the processing such the recorded broadcast data can be paused and then played from the paused time point. If a user instruction for playing the recorded broadcast data is detected, the control unit  100  determines whether a resume marker is set. When the resume marker function is initialized, the control unit  100  retrieves the packet identifier information corresponding to the initial system time from the back recorded broadcast data for playing the recorded broadcast data from the start point. When a resume marker is set, the control unit  100  retrieves the packet identifier information of the system time corresponding to the value satisfying a conditional expression for playing the recorded broadcast data from the time marked with the resume marker. 
     In an exemplary embodiment of the present invention, the conditional expression for the resume time can be expressed as shown in equation (1). 
       ((Time  N− 1)−Time 1≦resume time&lt;(Time  N )−Time 1),   (1) 
     where N is a number of PMT backup times during the broadcast data recording,
         Time N is the system time for N th  PMT backup,   Time N−1 is the system time for (N−1) th  PMT backup, and   Time  1  is a system time at which the broadcast recording starts.       

     For instance, the control unit  100  can set the resume time for starting the resume marker function to 7000 ms, the system time for (N−1) th  PMT backup to 105789 ms, the system time for N th  PMT backup to 109865 ms, and the system time for the start of recording the broadcast data to 100000 ms. Here, the control unit  100  can start playing the recorded broadcast data corresponding to the packet identifier information at the (N−1) th  PMT backup prior to the resume time. 
       FIG. 2  is a flowchart illustrating a method for recording and reproducing broadcast data according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , the control unit  100  plays the broadcast data received by means of the broadcast reception unit  150  in response to a user instruction ( 201 ). The broadcast data received through the broadcast reception unit  150  includes the Program Association Table (PAT). The PAT includes the Program Map Table (PMT) information. The PMT information includes packet identifiers (PID&#39;s). 
     While playing the broadcast data, the control unit  100  monitors the input unit for the detection of a user instruction. If a broadcast data recording instruction is detected, the control unit  100  starts recording the broadcast data ( 203 ). At this time, the control unit  100  stores the packet identifier information included in the PMT of the broadcast data that are currently playing together with the current system time. The control unit  100  extracts the video PID, audio PID, and data PID from the packet identifier information of the PMT and stores the PID&#39;s in the form of a table together with the system time. 
     If a recorded broadcast data playback instruction is detected, the control unit  100  analyzes the recorded broadcast data recorded ( 205 ). At this time, the control unit  100  can check the resume time for executing the resume marker function. Next, the control unit  100  determines the playback start time of the recorded broadcast data and the system time corresponding to the resume time. 
     If the system time for playing the recorded broadcast data is available, the control unit  100  acquires the packet identifier information corresponding to the system time and starts decoding to play the recorded broadcast data corresponding to the packet identifier information (S 207 ). 
       FIG. 3  is a flowchart illustrating a broadcast data recording procedure of a mobile terminal according to an exemplary embodiment of the present invention, and  FIGS. 4   a  to  4   c  are tables illustrating exemplary packet identifier information used in the broadcast data recording method according to an exemplary embodiment of the present invention. 
     Referring to  FIGS. 3 and 4   a  to  4   c , the control unit  100  displays the video data of the broadcast data received by means of the broadcast reception unit  150  in response to a broadcast data playback instruction input by the user ( 301 ). 
     While playing the broadcast data, the control unit  100  checks the PMT included in the broadcast data and extracts the packet identifier information from the PMT ( 302 ). 
     Next, the control unit  100  monitors the input unit for detecting a user instruction and, if a user instruction is input, determines whether the user instruction is a broadcast data recording instruction ( 303 ). 
     If a broadcast data recording instruction is detected, the control unit  100  starts recording the broadcast data that are currently playing ( 305 ). At this time, the broadcast data recording instruction is input by the user pushing a function key assigned for the broadcast data recording. When no broadcast data recording instruction is input, the control unit  100  keeps playing the broadcast data received through the broadcast reception unit  150  in real time. 
     Once the broadcast data recording starts, the control unit  100  stores the packet identifier information including the video PID, the audio PID, and the data PID in the storage unit  130  together with the system time in the form of a table ( 307 ). Here, the system time is the mobile terminal&#39;s local time at which the broadcast data recording starts. For instance, the control unit  100  stores the packet identifier information extracted from the PMT acquired from the broadcast data in the form of a table as shown in  FIG. 4   a . In an exemplary packet identifier information table of  FIG. 4   a , the packet data identifier information includes a video PID “0xAAAA”, an audio PID “0xBBBB”, and a data PID “0xCCCC”. 
     After storing the extracted packet identifier information and the system time, the control unit  100  compares the PMT extracted from the currently received broadcast data and the PMT extracted from the previously received broadcast data repeatedly and determines whether the PMT has changed ( 309 ). 
     When the change of the PMT is detected, the control unit  100  extracts the packet identifier information from the changed PMT and stores the extracted packet identifier information and the system time at which the PMT change is detected in the storage unit  130  at step  311 . For instance, the control unit  100  stores the packet identifier information extracted from the changed PMT acquired from the broadcast data in the form of a table as shown in  FIG. 4   b . In an exemplary packet identifier information table of  FIG. 4   b , the packet identifier information extracted from the change PMT includes a video PID “0xDDDD”, an audio PID “0xEEEE”, and a data PID “0xFFFF”. When the broadcast data recording starts, the control unit  100  stores the system time T 1  (Time  1 ) indicating the time point at which the broadcast data recording starts together with the packet identifier information acquired from the PMT as shown in  FIG. 4   c.    
     If the PMT is changed while recording the broadcast data, the control unit  100  extracts the packet identifier information from the changed PMT and stores the extracted packet identifier information together with the system T 2 (Time  2 ) at which the PMT is changed. The control unit  100  can repeat the PMT change inspection until the broadcast data recording is terminated. The control unit  100  extracts the packet identifier information from the changed PMT and stores the extracted packet identifier information together with the system time Tn (Time N) at which the PMT is changed finally. 
     Whenever the packet identifier information and the system time are stored, the control unit  100  determines whether a broadcast data recording termination instruction is input ( 313 ). 
     If no broadcast data recording termination instruction is detected, the process goes to step  309 . 
     Otherwise, if a broadcast data recording termination instruction is detected at step  313 , the control unit  100  stops recording the broadcast data ( 315 ). 
       FIG. 5  is a flowchart illustrating a recorded broadcast data playback procedure of a broadcast data playback method for a mobile terminal according to an exemplary embodiment of the present invention, and  FIG. 6  is a conceptual diagram illustrating the recorded broadcast data playback timing in the broadcast data playback method of  FIG. 5 . 
     Referring to  FIGS. 5 and 6 , the control unit  100  detects a recorded broadcast data playback instruction input by the user ( 501 ). If a recorded broadcast data playback instruction is detected, the control unit  100  determines whether a resume marker is set with the recorded broadcast data ( 503 ). 
     If a resume marker is not set with the recorded broadcast, the control unit  100  selects the initial packet identifier information acquired when the broadcast data playback started ( 507 ). At this time, the control unit  100  recognizes that the recorded broadcast data playback is requested to start from the initial recording start time. Otherwise, if a resume marker is set with the recorded broadcast data, the control unit  100  checks the resume time at which the resume marker is pointing ( 505 ). Here, the resume time is a time point at which the recorded broadcast data playback was paused. At this time, the control unit  100  can check the system time with reference to the resume time for acquiring the playback elapsed time of the recorded broadcast data. 
     Next, the control unit  100  determines whether the resume time satisfies the conditional expression ( 509 ). At this time, the control unit  100  may check the packet identifier information appropriate for the recorded broadcast data depending on the system time. 
     In an exemplary embodiment of the present invention the conditional expression can be expressed as equation (1). 
       ((Time  N -1)−Time 1≦resume time&lt;(Time  N )−Time 1),   (1)         where N is a number of PMT backup times during the broadcast data recording,
           Time N is the system time for N th  PMT backup,   Time N−1 is the system time for (N−1) th  PMT backup, and   Time  1  is a system time at which the broadcast recording starts.   
               
     The control unit  100  determines the system time corresponding to the resume time according to the conditional expression. If the resume time does not satisfy the conditional expression, the control unit  100  increments the value N, which denotes the number of system PMT back times, by 1 ( 511 ) and repeats the determination process. In this manner, the control unit  100  can find a system time which is prior to the resume time. If the resume time satisfies the conditional expression at step  509 , the control unit  100  selects the packet identifier information corresponding to the system time ( 513 ). For instance, when a resume marker is set with the recorded broadcast data, the control unit  100  checks the resume time A for executing the resume marker function as shown in  FIG. 6 . The control unit  100  applies the resume time to the conditional expression to acquire the system time satisfying the conditional expression. In this case, the control unit  100  acquires the packet identifier information stored in correspondence with the system time T 2  at which the PMT is first changed while recording the broadcast data. Once the packet identifier information is selected, the control unit  100  starts playback of the recorded broadcast data using the acquired packet identifier. In case when no resume marker is detected from the recorded broadcast data, the control unit  100  checks the system time Ti at which the broadcast data recording started. 
     Once the packet identifier information is determined at step  513  or  507 , the control unit  100  starts playback of the broadcast data using the packet identifier information ( 515 ). 
     The above-described methods according to the present invention can be realized in hardware or as software or computer code that can be stored in a recording medium such as a CD ROM, an RAM, a floppy disk, a hard disk, or a magneto-optical disk or downloaded over a network, so that the methods described herein can be executed by such software using a general purpose computer, or a special processor or in programmable or dedicated hardware, such as an ASIC or FPGA. As would be understood in the art, the computer, the processor or the programmable hardware include memory components, e.g., RAM, ROM, Flash, etc. that may store or receive software or computer code that when accessed and executed by the computer, processor or hardware implement the processing methods described herein. 
     Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims. 
     As described above, the broadcast recording and reproducing method and apparatus for the mobile terminal according to the present invention is advantageous to record the broadcast data in which the PMT is acquired at a relatively long interval and minimize the data loss occurring before acquiring the PMT.