Patent Publication Number: US-2015077635-A1

Title: Method for outputting multiple multimedia tracks along multiple processing paths from a portable electronic device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates audio processing, and in particular, to a portable electronic device and a method for outputting multiple multimedia tracks along multiple processing paths. 
     2. Description of the Related Art 
     With advances in technologies, portable electronic devices such as smartphones and tablet PCs have become widely used. However, due to limited resources, multimedia tracks (e.g. audio signals and/or image signals) of applications running on a conventional portable electronic device are usually processed by the same processing thread. As a result, when the content of the conventional portable electronic device is mirrored to an external device, it is very inconvenient for the user since the audio signals of all the applications will be mirrored to the external device without being controlled separately and independently. 
     BRIEF SUMMARY OF THE INVENTION 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     In an exemplary embodiment, a method for outputting multiple multimedia tracks along multiple processing paths from a portable electronic device is provided. The method has the steps of: running at least two applications on the portable electronic device; accessing at least two multimedia tracks corresponding to the at least two applications; processing the at least two multimedia tracks along at least two processing paths; transferring the at least two multimedia tracks to at least two output terminals; and playing the at least two multimedia track by the at least two output terminals; wherein at least one of the at least two output terminals is external to the portable electronic device. 
     In another exemplary embodiment, a method for outputting multiple multimedia tracks along multiple processing paths from a portable electronic device is provided. The method has the steps of: running a first application on the portable electronic device; processing a first multimedia track corresponding to the first application along a first processing path; outputting the first multimedia track to a first multimedia output terminal; launching a second application during running of the first application on the portable electronic device; receiving a first user input for selecting a second multimedia output terminal corresponding to the second application; processing a second multimedia track corresponding to the second application along a second processing path according to the first user input; and outputting the second multimedia track to the second multimedia output terminal, wherein one of the first multimedia output terminal and the second multimedia output terminal is internal to the portable electronic device, and the other is external to the portable electronic device. 
     In yet another exemplary embodiment, an apparatus for outputting multiple multimedia tracks along multiple processing paths is provided. The method has the following steps of: a processing unit, configured to run a first application and a second application in parallel, and to process a first multimedia track corresponding to the first application and a second multimedia track corresponding to the second application along a first processing path and a second processing path respectively; at least one multimedia codec unit, configured to encode and decode the first multimedia track and the second multimedia track; at least one internal multimedia output terminal, configured to receive and play the first multimedia track from the first processing path; and a transmission interface unit, configured to transmit the second multimedia track from the second processing path to a first external multimedia output terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a schematic diagram illustrating a portable electronic device  100  according to an embodiment of the invention; 
         FIG. 2  is a diagram illustrating audiovisual content control of application in a conventional portable electronic device; 
         FIG. 3  is a diagram illustrating audiovisual content control of application in a portable electronic device according to an embodiment of the invention; 
         FIG. 4A-4C  are diagrams illustrating the operations for selecting an output terminal of an application in a user interface according to an embodiment of the invention; 
         FIG. 5  is a diagram illustrating audiovisual content control of application in a portable electronic device according to another embodiment of the invention; 
         FIG. 6  is a flow chart illustrating the method for outputting multiple multimedia tracks along multiple processing paths from a portable electronic device according to an embodiment of the invention; and 
         FIG. 7  is a flow chart illustrating the method for outputting multiple multimedia tracks along multiple processing paths from a portable electronic device according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       FIG. 1  is a schematic diagram illustrating a portable electronic device  100  according to an embodiment of the invention. The portable electronic device  100  may comprise a processing unit  110 , a memory unit  120 , a display screen  140 , a transmission interface unit  170 , a multimedia interface unit  180 , and a codec unit  190 . In an exemplary embodiment, the portable electronic device  100  may be a portable device such as a mobile phone, tablet, digital camera/camcorder, game console or any suitable device. The processing unit  110  may be data processing units, image processing units, application processing units and/or central processing units, and is capable of executing one or more types of computer readable medium stored in the memory unit  120 . Additionally, the portable electronic device  100  may further comprise RF circuitry  160 . In the embodiments, the display screen  140  may be a touch-sensitive screen. 
     The RF circuitry  160  may be coupled to one or more antennas  165  and may allow communications with one or more additional devices, computers and/or servers via a wireless network. The portable electronic device  100  may support various communications protocols, such as the code division multiple access (CDMA), Global System for Mobile Communications (GSM), Enhanced Data GSM Environment (EDGE), High-Speed Downlink Packet Access (HSDPA), Wi-Fi (such as IEEE 802.11a/b/g/n), Bluetooth, and Wi-MAX communication protocol, and a protocol for emails, instant messaging (IM), and/or a short message services (SMS), but the invention is not limited thereto. 
     When the display screen  140  is implemented as a touch-sensitive screen, it may detect contact and any movement or break thereof by using any of a plurality of touch sensitivity technologies now known or to be later developed, including, but not limited to, capacitive, resistive, infrared, and surface acoustic wave touch sensitivity technologies, as well as other proximity sensor arrays or other elements for determining one or more points of contact with the touch-sensitive screen. However, the touch-sensitive screen may also display the visual output of the portable electronic device  100 . In some other embodiments, the portable electronic device  100  may include circuitry (not shown in  FIG. 1 ) for supporting a location-determining capability, such as that provided by a Global Positioning System (GPS). 
     The memory unit  120  may comprise one or more types of computer readable medium. The memory unit  120  may be high-speed random access memory (e.g. SRAM or DRAM) and/or non-volatile memory, such as flash memory (for example an embedded multi-media card). The memory unit  120  may store program codes of an operating system  122 , such as LINUX, UNIX, OS X, Android, iOS or WINDOWS operating system, or an embedded operating system therein such as VxWorks. The operating system  122  may execute procedures for handling basic system services and for performing hardware dependent tasks. The memory unit  120  may also store the communication programs  124  for executing communication procedures. The communication procedures may be used for communicating with one or more additional devices, one or more computers and/or one or more servers. The memory unit  120  may comprise display programs  125 , contact/motion programs  126  to determine one or more points of contact and/or their movement, and a graphics processing programs  128 . The graphics processing programs  128  may support widgets, i.e., modules or applications with embedded graphics. The widgets may be implemented using JavaScript, HTML, Adobe Flash, or other suitable computer programming languages and technologies. 
     The memory unit  120  may also comprise one or more application programs  130 . For example, application programs stored in the memory unit  120  may be telephone applications, email applications, text messaging or instant messaging applications, memo pad applications, address books or contact lists, calendars, picture taking and management applications, and music playback and management applications. The application programs  130  may comprise a web browser (not shown in  FIG. 1 ) for rendering pages written in the Hypertext Markup Language (HTML), Wireless Markup Language (WML), or other languages suitable for composing web pages or other online content. The memory unit  120  may further comprise keyboard input programs (or a set of instructions)  131 . The keyboard input programs  131  operate one or more soft keyboards. 
     The memory unit  120  may also comprise a codec program  132  for processing audiovisual data generated by the applications  130 . For example, the portable electronic device  100  may further comprise a codec unit  190 , which may be an application-specific integrated circuit (ASIC) or a DSP, configured to perform encoding/decoding (codec) processes on audiovisual data. The audiovisual data generated by the applications  130  can be processed by hardware (e.g. codec unit  190 ) or software (e.g. codec program  132  executed by the processing unit  110 ). Furthermore, the audio/video processing can be performed by hardware and software concurrently. 
     It should be noted that each of the above identified programs and applications corresponds to a set of instructions for performing one or more of the functions described above. These programs (i.e., sets of instructions) need not be implemented as separate software programs, procedures or modules. The various programs and sub-programs may be rearranged and/or combined. Various functions of the portable electronic device  100  may be implemented in software and/or in hardware, including one or more signal processing and/or application-specific integrated circuits. 
     The transmission interface unit  170  is configured to transmit audio/video signals generated by the applications  130  to at least one external multimedia terminal (e.g. TV, Bluetooth headset, and etc.) in a wireless network protocol, such as Wifi, Bluetooth, LAN, etc. In addition, transmission of audio/video signals can be implemented by Miracast, DLNA, WiDi, and/or other known standards, and the processing unit  110  may encode the output audio/video signals according to the selected transmission protocol/standard. 
     The multimedia interface unit  180  may comprise various physical interfaces configured to transmit audio/video signals generated by the applications  130  to local multimedia terminals (e.g. display, speakers, and etc.) which are connected to the portable electronic device  100  via the multimedia interface unit  180 . 
       FIG. 2  is a diagram illustrating audiovisual content control of application in a conventional portable electronic device. As illustrated in  FIG. 2 , an audio processing thread  250  and an image processing thread  260  are executed by the processing unit  210  of the conventional portable electronic device  200 . The audio processing thread  250  is configured to perform audio processing of all applications (e.g. applications  2301 ,  2302  and  2303 ) running on the conventional portable electronic device  200  with the support of an audio codec unit  240  to generate output audio signals. Similarly, the image processing thread  260  is configured to perform image processing of all applications running on the conventional portable electronic device  200  with the support of a video codec unit  230  to generate output video signals. Accordingly, the audio tracks of all the applications running on the conventional portable electronic device  200  are processed by the same audio processing thread  250  as well as the images of all the applications running on the portable electronic device  200  being processed by the same image processing thread  260 . 
     Specifically, the conventional portable electronic device  200  may support the “Mirror” mode, which indicates that all the output audio/video/image signals of the portable electronic device  200  are transmitted to another external device, such as a TV  290  or Bluetooth headset  292 . In other words, there is only one processing path for the audio/video/image signals of the applications running on the portable electronic device  200 . However, in the “Mirror” mode, the external device can only display exactly the same content with the conventional portable electronic device  200 . Accordingly, the audio/image signals of all the applications running on the conventional portable electronic device  200  cannot be controlled separately and independently. 
       FIG. 3  is a diagram illustrating multimedia content control of application in a portable electronic device according to an embodiment of the invention. As illustrated in  FIG. 3 , thread  310  and thread  320 , which are executed by the processing unit  110 , are responsible for processing multimedia tracks generated by the applications  130 . The thread  310  and thread  320  may be audio processing threads or image processing threads. In practical implementation, audio signals and video signals are processed separately. However, for a brief description, the thread  310  and thread  320  can be regarded as multimedia processing threads capable of executing codec firmware/codes for processing audio signals, image signals and video signals simultaneously. 
     In the embodiment of  FIG. 3 , the processing unit  110  is capable to run multiple threads  310  and  320  concurrently at the same time. Each of the threads  310  and  320  corresponds to one of available multimedia output terminals. Available multimedia terminals may comprise local multimedia output terminals and external multimedia output terminals detected by and connected to the portable electronic device  100 . The thread  310  corresponds to a local multimedia output terminal, which may be the speaker  150  for audio playing and display unit  140  for image/video displaying. Since a local multimedia output terminal is always present and used by user, the thread  310  may be executed by the processing unit  110  permanently. The thread  320  corresponds to an external multimedia output terminal, such as TV  380  in  FIG. 3 , and it can be created only when the TV  380  is detected by and/or connected to the portable electronic device  100 . In another embodiment of the invention, the thread  320  can be created when the TV  380  is selected for outputting multimedia tracks of an application even though it has been detected and connected. When an application is running, the multimedia track corresponding to the application is directed to and processed by one of the threads  310  or  320  according to the multimedia output terminal used for outputting the multimedia track. In order to specify which multimedia output terminal is used for outputting the multimedia track of the application, an identifier is attached to the multimedia track. The identifier comprises information about the application and the thread corresponding to the multimedia output terminal. By attaching the identifier, it can be determined whether the multimedia track should be directed to and processed by the thread  310  or the thread  320 . For example, the multimedia track  351  of the application  131  is attached with an identifier comprising information specifying the application  1301  and the thread  310 . Upon receiving the multimedia track  351 , the processing unit  110  would send the multimedia track  351  to the thread  310  accordingly since the identifier indicates that it should be processed by the thread  310 . Similarly, the multimedia track  353  is attached with another identifier comprising information about the application  1303  and the thread  320 . The multimedia output terminal for outputting multimedia tracks of applications may be selected by user via a user interface, which may be provided on the display unit  140 . For example, the local multimedia terminals such as the display unit  140  and the speaker  150  may be set as the default multimedia output terminals. However, the user may choose to output the multimedia track  253  of the application  1303  to the TV  380  via the user interface. In response to the user selection, the identifier attached to the multimedia track  353  would comprise information specifying the thread  320  corresponding to the TV  320  rather than the thread  310 . 
     In an embodiment, the multimedia track (e.g. multimedia track  351 ) generated by the application  1301  is directed to the thread  310 , which performs processes for outputting multimedia tracks to local multimedia output terminals (e.g. touch screen, speaker, and ear jack), via the first processing path  350 . In addition, the multimedia track (e.g. track multimedia  353 ) generated by the application  1303  is directed to the thread  320 , which performs processes for outputting multimedia tracks to external multimedia output terminals (e.g. TV  380 , or speakers, Bluetooth headset, etc.), via the second processing path  360 . Further, the transmission interface unit  170  may receive the output multimedia tracks from the thread  320  and transmit the multimedia tracks to the external multimedia output terminal in a wireless protocol, such as Wifi, Bluetooth, LAN, etc. The transmission of the output multimedia tracks can be implemented by Miracast, DLNA, Widi and/or other known standards, and the output multimedia tracks are encoded by the codec unit  190  based on the selected transmission protocol. 
     Also note that, multimedia tracks for more than one application may be received and processed by each of the thread  310  and thread  320 . In the embodiment of  FIG. 3 , the thread  310  receives the multimedia track  351  of the application  1301  and multimedia track  352  of application  1302 , and processes them to generate an output multimedia track to the multimedia interface unit  180 . Put it in simple, multimedia tracks  351  and  352  can be mixed by thread  310  to produce the output multimedia track. In the case for audio tracks, a mixed audio track comprising audio tracks of applications  1301  and  1302  is played by the speaker  150 , and in the case for image tracks, a mixed image track comprising images of application  1301  and  1302  is displayed on the display unit  140 . 
     In the embodiment of  FIG. 3 , thread  310  is responsible for processing the multimedia tracks  351  and  352  to be outputted to local multimedia output terminals, such as the speaker  150  and the display unit  140 . Meanwhile, the thread  320  is responsible for processing the multimedia track  353 , which is outputted to an external multimedia output terminal, such as the TV  380 . The threads  310  and  320  may be run concurrently in parallel by the processing unit  110  for producing multimedia outputted to both local and external multimedia output terminals at the same time. Please note that in other embodiments of the invention, there may be more than two threads running by the processing unit  110  in the case that more than one external multimedia output terminal is connected to the portable electronic device  100 . For example, in the case that there are two external TVs connected to the portable electronic device  100 , two additional threads may be run by the processing unit  110  in addition to the thread  310 . Each of the additional thread corresponds to one of the external TVs and is responsible for processing multimedia tracks to be outputted to the corresponding external TV. 
       FIG. 4A-4C  are diagrams illustrating the operations for selecting an output terminal of an application via a user interface according to an embodiment of the invention. When an application is launched and running, the multimedia track of the application can be outputted to a designated multimedia terminal by selecting one of the output modes via the user interface of the application. For example, as illustrated in  FIG. 4A , when the “Mirror” mode is selected, the processing unit  110  may duplicate all the multimedia tracks of the application  410  on the portable electronic device  100  to a TV  380 . In another embodiment of the invention, the image contents of the application  410  are displayed on both the display unit  140  and the TV  380 , but the audio tracks of the multimedia track of the application  410  are only played by the TV  380 . When the “Extend” mode is selected, the processing unit  110  may output image contents to the TV  380 , and the portable electronic device  100  can be used as a controller (e.g. a control pad). One exemplary scenario in the “Extend” mode is that the TV is used to display game images, and the portable electronic device  100  is used as a control pad to control contents in the game. When a “Multi” mode is selected, the processing unit  110  may output the content of the application  410  externally to the TV  380 . Meanwhile, another application  420  can be executed and displayed on the display unit  140  of the portable electronic device  100  simultaneously as shown in  FIG. 4C . In other words, the application  410  may be regarded as a background task while the application  420  is executed as a primary application, which is currently displayed on the display unit  140  of the portable electronic device  100 . It should be noted that the application  410  and the application  420  can be running concurrently in parallel. 
     As illustrated in  FIG. 4B , when the user selects the “Multi” mode, the portable electronic device  100  may display a user interface to provide options of available multimedia output terminals, such as “Phone”, “TV-1”, and “TV-2”. When the option “Phone” is selected, it may indicate that the audio and video contents of the application  420  will be directed to the local speaker  150  and the display unit  140  of the portable electronic device  100  respectively. Regarding the options “TV-1” and “TV-2”, it may indicate that TV-1 and TV-2 are external terminals which have been previously paired with and registered to the portable electronic device  100 . In addition, the portable electronic device  100  may constantly detect whether any previously paired multimedia terminal can be used for multimedia transmission exists. Furthermore, the portable electronic device  100  may detect whether an unknown multimedia terminal (i.e. not previously paired or registered) appears and can be connected to. In the embodiment, the option “TV-1” is selected for the application  410  and the audio/visual content of the application  410  is transmitted to the TV-1, as illustrated in  FIG. 4B . Afterwards, the application  420  can be run and the audio/visual content of the second application  420  can be displayed locally in the portable electronic device  100  while the content of the application  410  is displayed on the TV-1 concurrently, as illustrated in  FIG. 4C . It should be noted that the audio/visual data of the first application and the second application are both processed by the portable electronic device  100 . 
       FIG. 5  is a diagram illustrating audio/visual content control of application in a portable electronic device according to another embodiment of the invention. As illustrated in  FIG. 5 ,  3  applications  1501 ,  1502  and  1503  are running in the portable electronic device  100  concurrently. In addition, three threads  1511 ,  1512 , and  1513  are executed by the processing unit  110  of the portable electronic device  100 . Specifically, the multimedia track  1521  corresponding to the application  1501  is directed to the thread  1511  via the first processing path  1531 , and the thread  1511  may process the multimedia track  1521  and further transmit the processed multimedia track  1521  to the local display unit  140  and the speaker  150  through the multimedia interface unit  180 . The multimedia track  1522  corresponding to the application  1502  is directed to the thread  1512  via the second processing path  1532 , and the thread  1512  may process the multimedia track  1522  and further transmit the processed multimedia track  1522  to the TV  510  via the transmission interface unit  170 . In addition, the multimedia track  1523  corresponding to the application  1503  is directed to the thread  1513  via the third processing path  1533 , and the thread  1513  may process the multimedia track  1523  and further transmit the processed multimedia track  1523  to the TV  512  via the transmission interface unit  170 . For example, the hardware codec unit  190  may perform audio/image/video encoding/decoding of the multimedia track  1521 , and the software codec program  132  executed by the processing unit  110  may perform audio/image/video encoding/decoding of the multimedia tracks  1522  and  1523 . In other embodiments of the invention, the multimedia tracks  1521 ˜ 1523  may be encoded and/or decoded solely by the hardware codec unit  190  or the software codec program  132  depending on the system requirements or performance. In yet another embodiment of the invention, the multimedia tracks  1521 ˜ 1523  may be processed by the hardware codec unit  190  or the software codec program  132  according to the coding formats supported by the codec unit  190  and the codec program  132 . It should be noted that the coordination of hardware/software codec is known to those skilled in the art, and the details will be omitted here. 
     Similar to the embodiment of  FIG. 3 , the treads  1511 ˜ 1513  may be run concurrently in parallel by the processing unit  110  so as to provide multimedia outputs to the local and external multimedia terminals at the same time. Each of the threads  1511 ˜ 1513  corresponds to one of the multimedia terminals. That is, the portable electronic device  100  is capable of running the applications  1501 ˜ 1503  and providing contents of the applications to different multimedia terminals at the same time. As described in the embodiments of  FIG. 4A˜4C , the user is able to configure which multimedia output terminal to be used to provide output from a designated application via the user interface. Also in other embodiments of the invention, in the case that two or more applications are designated to the same multimedia terminal, the thread corresponding to the multimedia terminal would process multimedia tracks of the applications. Also, the multimedia tracks  1521 ˜ 1523  are attached with identifiers comprising information about corresponding applications and threads so that the multimedia tracks  1521 ˜ 1523  can be directed to corresponding threads  1511 ˜ 1523  correctly. 
       FIG. 6  is a flow chart illustrating the method for outputting multiple multimedia tracks along multiple processing paths from a portable electronic device according to an embodiment of the invention. In step S 610 , at least two applications are running on the portable electronic device  100 . In step S 620 , the processing unit  110  may access at least two multimedia tracks corresponding to the at least two applications. The multimedia tracks may be accessed from internal memory or external memory, for example from the internet. In step S 630 , the at least two multimedia tracks are processed along at least two processing paths. It is noted that the processing unit  110  also creates multimedia threads in the first processing paths, and the multimedia tracks are encoded/decoded by a hardware codec unit (e.g. codec unit  190 ) and/or software codec program (e.g. codec program  132 ). The processing unit  110  may also attach identifiers to the multimedia tracks for specifying which processing paths they should be directed to. The identifiers comprise information about corresponding applications and multimedia threads, so that the processing unit  110  may direct the multimedia tracks to the corresponding processing paths correctly based on the identifiers. 
     In step S 640 , the processing unit  110  may further transfer the multimedia tracks to at least two output terminals. The output terminals may be local terminals and/or external terminals. In the embodiment of the invention, at least one of the output terminals is external to the portable device  100 . In step S 650 , the at least two multimedia tracks can be played by the at least two output terminals. It should be noted that one of the output terminal may be an external output terminal and the other output terminal may be an internal output terminal. Additionally, the processing unit  110  may keep detecting the presence of the at least two output terminals (particularly the external output terminals), and create corresponding processing paths in response to the detected presence of the output terminals. In other words, when there is no external output terminal connected to the portable electronic device  100 , the processing unit  110  may not create the processing thread and the processing path associated with the external output terminal. It should be noted that the transmission of the multimedia track to the external output terminal is implemented by one of the following wireless transmission protocols: Wifi (e.g. Wifi Direct or Miracast), Bluetooth, LAN, and/or other suitable protocols. And the multimedia track to be transferred to the external output terminal can be encoded according to the wireless transmission protocol. Please also note that the portable electronic device  100  may provide a user interface to the user. Use may send user input via the user interface for selecting an output terminal to be used for outputting audio/visual content of an application. According to the user input, the processing unit  110  configures the applications so that the multimedia tracks of the applications can be sent to corresponding threads for processing. 
       FIG. 7  is a flow chart illustrating the method for outputting multiple multimedia tracks along multiple processing paths from a portable electronic device according to another embodiment of the invention. In step S 710 , a first application is running on the portable electronic device. In step S 720 , the processing unit  110  may process a first multimedia track corresponding to the first application along a first processing path. In step S 730 , the processing unit  110  may further output the processed first multimedia track to a first multimedia output terminal. In step S 740 , a second application is launched during the running of the first application on the portable electronic device  100 . It should be noted that the scenario of  FIG. 7  indicates that a new application is launched and run with the existing processing path of a running application. In step S 750 , a first use input is received via a user interface (e.g. a touch event on the user interface displayed on the display unit  140 ). The first user input may be used to select a second multimedia output terminal corresponding to the second application. Afterwards, in step S 760 , the processing unit  110  may process a second multimedia track corresponding to the second application along a second processing path according to the first user input. In step S 770 , the processing unit  110  may output the second multimedia track to the second multimedia output terminal. It should be noted that one of the first multimedia output terminal and the second multimedia output terminal is internal to the portable electronic device  100 , and the other one of the first multimedia output terminal and the second multimedia output terminal is external to the portable electronic device  100 . In other words, when the existing processing path is associated with an internal output terminal, the newly created processing path can be directed to an external output terminal. Conversely, when the existing processing path is associated with an external output terminal, the newly created processing path can be directed to an internal output terminal. Additionally, the processing unit  110  may further switch the first multimedia track or the second multimedia track to be processed in another processing path (e.g. the second processing path and the first processing path, respectively) in response to user input (e.g. a touch event on the user interface displayed on the display unit  140 ). 
     Specifically, the processing unit  110  may modify the first identifier of the first application to correspond to another processing path associated with a specific output terminal, and then the processing unit  110  may switch the first multimedia track corresponding to the first application to the specific output terminal according to the modified first identifier. Similarly, the processing unit  110  may modify the second identifier of the second application to correspond to another processing path associated with a specific output terminal, and then the processing unit  110  may switch the second multimedia track corresponding to the second application to the specific output terminal according to the modified second identifier. It should be noted that the specific output terminal can be selected from the existing internal/external output terminal or an additional external output terminal. When the selected specific output terminal is exactly the additional external output terminal, the processing unit  110  may create a third processing path (in addition to the first/second processing paths) to process switching of the first/second multimedia tracks. Also similarly to the embodiment of  FIG. 6 , in the case that the multimedia track is to e outputted to an external output terminal, the multimedia track can be encode by suitable transmission protocol. 
     The methods, or certain aspects or portions thereof, may take the form of a program code embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable (e.g., computer-readable) storage medium, or computer program products without limitation in external shape or form thereof, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine thereby becomes an apparatus for practicing the methods. The methods may also be embodied in the form of a program code transmitted over some transmission medium, such as an electrical wire or a cable, or through fiber optics, or via any other form of transmission, wherein, when the program code is received and loaded into and executed by a machine such as a computer, the machine becomes an apparatus for practicing the disclosed methods. When implemented on a general-purpose processing unit, the program code combines with the processing unit to provide a unique apparatus that operates analogously to application-specific logic circuits. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.