Patent Publication Number: US-2020304917-A1

Title: Method and electronic device for transmitting audio data to multiple external devices

Description:
PRIORITY 
     This application is a Continuation Application of U.S. patent application Ser. No. 15/870,286, filed in the U.S. Patent and Trademark Office on Jan. 12, 2018, and claims priority under 35 U.S.C. § 119(a) to a Korean Patent Application filed in the Korean Intellectual Property Office on Mar. 24, 2017 and assigned Ser. No. 10-2017-0037889, the contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     Embodiments of the present disclosure relate to methods and electronic devices for transmitting audio data to multiple external devices. 
     2. Discussion of the Related Art 
     Recent wide-spread use of electronic devices supportive of short-range wireless communication, such as, for example, Bluetooth communication, is leading to a growing use of media streaming services among the electronic devices via short-range wireless communication. For example, an electronic device supportive of Bluetooth communication may transmit audio data to an external electronic device (e.g., a headset, a speaker, earphones, or a smartphone) connected via Bluetooth communication using the advanced audio distribution profile (A2DP), and the external electronic device may receive and output the audio data. The external electronic device may control playback-related functions (e.g., play, pause, skip, volume control, and/or mute) of the playing audio data. 
     An electronic device supporting short-range wireless communication, such as, for example, Bluetooth communication, may be connected to multiple external devices via Bluetooth communication. When the multiple external devices use different codecs to process audio data received from the electronic device via Bluetooth communication, a problem may arise as the electronic device transmits audio data to the multiple external devices for audio streaming. 
     Bluetooth communication is performed within a limited frequency band, and the amount of data transmitted is limited. Thus, if the electronic device transmits audio data to each external device, the amount of data transmitted increases, resulting in possible quality deterioration (e.g., sound drops) of audio output from the external devices. 
     SUMMARY 
     According to aspects of the present disclosure, an electronic device and a method are provided for transmitting audio data to multiple external devices through Bluetooth communication. 
     Accordingly, an aspect of the present disclosure provides an electronic device including a wireless communication circuit, a touchscreen display, and at least one processor, wherein the at least one processor is configured to establish a first short-range wireless channel with a first external device using the wireless communication circuit, establish a second short-range wireless channel with a second external device using the wireless communication circuit, wherein a first audio output from the first external device and a second audio output from the second external device are substantially identical, display, on the touchscreen display, at least one graphical object indicating that the first external device and the second external device are connected to the electronic device, wherein the at least one graphical object represents a type of the first external device and the second external device, the type including an earphone, identify a user input for adjusting a volume output from at least one of the first external device and the second external device, while the at least one graphical object is displayed on the touchscreen display, in response to determining that the user input for adjusting the volume is for commonly adjusting a first volume output from the first external device and a second volume output from the second external device, commonly adjust the first volume and the second volume, and in response to determining that the user input for adjusting the volume is for adjusting the first volume, adjust the first volume while the second volume is maintained. 
     Another aspect of the present disclosure provides an electronic device including a wireless communication circuit, a touchscreen display, and at least one processor configured to establish a first short-range wireless channel with a first external device using the wireless communication circuit, establish a second short-range wireless channel with a second external device using the wireless communication circuit, display, on the touchscreen display, a user interface screen for setting a dual audio function for transmitting audio data to a plurality of external devices, the user interface screen including a first graphical object corresponding to a type of the first external device and a second graphical object corresponding to a type of the second external device, and during an execution of the dual audio function in which audio data is transmitted to the first external device and the second external device, receive a first user input for adjusting a volume commonly for the first external device and the second external device, and receive a second user input for adjusting a volume for one of the first external device and the second external device while a volume for another of the first external device and the second external device is maintained. 
     Another aspect of the present disclosure provides an electronic device including a display, a wireless communication circuit configured to support wireless communication, a processor electrically connected with the display and the wireless communication circuit, and a memory electrically connected with the processor, and storing a plurality of applications, a plurality of codecs for processing audio data, and instructions, which when executed, enable the processor to: establish a first wireless channel with a first external device using the wireless communication circuit, establish a second wireless channel with a second external device using the wireless communication circuit, select a codec commonly supported by both the first external device and the second external device from among the plurality of codecs, process the audio data using the selected codec, transmit the processed audio data to the first external device via the first wireless channel and to the second external device via the second wireless channel using the wireless communication circuit, and display at least a first user interface representing a first application of the plurality of applications, wherein, upon a selection of the first user interface, the first application enables control of a function of the processed audio data for each of the first external device and the second external device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of the present disclosure will be more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram illustrating a network environment including an electronic device, according to an embodiment of the present disclosure; 
         FIG. 2  is a block diagram illustrating a program module, according to an embodiment of the present disclosure; 
         FIG. 3  is a block diagram illustrating an electronic device, according to an embodiment of the present disclosure; 
         FIG. 4  is a flowchart illustrating a method for transmitting audio data by an electronic device, according to an embodiment of the present disclosure; 
         FIG. 5  is a flowchart illustrating a method for selecting a codec to process audio data by an electronic device, according to an embodiment of the present disclosure; 
         FIG. 6  is a flowchart illustrating a method for operating an electronic device after deactivating an operation mode for transmitting audio data to multiple external devices, according to an embodiment of the present disclosure; 
         FIG. 7  is a diagram illustrating a method for transmitting audio data to multiple external devices by an electronic device, according to an embodiment of the present disclosure; 
         FIG. 8A  is a diagram illustrating a screen for setting an operation mode to transmit audio data to multiple external devices, which is displayed on an electronic device, according to an embodiment of the present disclosure; 
         FIG. 8B  is a diagram illustrating a home screen in a state where an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure; 
         FIG. 8C  is a diagram illustrating a standby screen and a lock screen in a state where an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure; 
         FIG. 8D  is a diagram illustrating a status bar that is expanded depending on whether an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure; 
         FIG. 8E  is a diagram illustrating a volume control screen in a state where an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure; 
         FIG. 9  is a diagram illustrating a method for setting an operation mode for transmitting audio data to multiple external devices, according to an embodiment of the present disclosure; 
         FIGS. 10A and 10B  are diagrams illustrating a method for setting an operation mode for transmitting audio data to multiple external devices on an electronic device, according to an embodiment of the present disclosure; 
         FIG. 11  is a flowchart illustrating a method for reducing the transmission speed of audio data transmitted to multiple external devices by an electronic device, according to an embodiment of the present disclosure; 
         FIG. 12  is a flowchart illustrating a method for reducing the transmission speed of audio data transmitted to one of multiple external devices by an electronic device, according to an embodiment of the present disclosure; 
         FIG. 13  is a flowchart illustrating a method for increasing the transmission speed of audio data transmitted to multiple external devices by an electronic device, according to an embodiment of the present disclosure; 
         FIG. 14  is a flowchart illustrating a method for increasing the transmission speed of audio data transmitted to one of multiple external devices by an electronic device, according to an embodiment of the present disclosure; 
         FIG. 15  is a flowchart illustrating a method for establishing a wireless channel with an external device by an electronic device, according to an embodiment of the present disclosure; and 
         FIG. 16  is a flowchart illustrating a method for transmitting audio data to multiple external devices by an electronic device, according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described in detail with reference to the accompanying drawings. Similar components are designated by similar reference numerals although they are illustrated in different drawings. Detailed descriptions of constructions or processes known in the art may be omitted to avoid obscuring the subject matter of the present disclosure. 
     The present disclosure is not limited to the embodiments and the terminology used herein, and all changes and/or equivalents or replacements thereto also belong to the scope of the present disclosure. It is to be understood that the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. As used herein, the terms “A or B” and “at least one of A and/or B” may include all possible combinations of A and B. As used herein, the terms “first” and “second” may modify various components regardless of importance and/or order and are used to distinguish a component from another without limiting the components. When an element (e.g., a first element) is referred to as being (operatively or communicatively) “coupled with/to” or “connected with/to” another element (e.g., a second element), it can be coupled or connected with/to the other element directly or via a third element. 
     As used herein, the terms “configured to (or designated)” may be interchangeably used with other terms, such as “suitable for”, “capable of”, “modified to”, “made to”, “adapted to”, “able to”, or “designed to” in hardware or software in the context. Rather, the term “configured to” may mean that a device can perform an operation together with another device or part. For example, the term “processor configured (or designated) to perform A, B, and C” may mean a generic-purpose processor (e.g., a central processing unit (CPU) or application processor (AP)) that may perform the operations by executing one or more software programs stored in a memory device or a dedicated processor (e.g., an embedded processor) for performing the operations. 
     Examples of the electronic device, according to embodiments of the present disclosure, may include at least one of a smartphone, a tablet personal computer (PC), a mobile phone, a video phone, an e-book reader, a desktop PC, a laptop computer, a netbook computer, a workstation, a server, a personal digital assistant (PDA), a portable multimedia player (PMP), a MP3 player, a medical device, a camera, or a wearable device. The wearable device may include at least one of an accessory-type device (e.g., a watch, a ring, a bracelet, an anklet, a necklace, glasses, contact lenses, or a head-mounted device (HIVID)), a fabric- or clothes-integrated device (e.g., electronic clothes), a body attaching-type device (e.g., a skin pad or tattoo), or a body implantable device. In some embodiments, examples of the smart home appliance may include at least one of a television, a digital video disk (DVD) player, an audio player, a refrigerator, an air conditioner, a cleaner, an oven, a microwave oven, a washer, a drier, an air cleaner, a set-top box, a home automation control panel, a security control panel, a TV box, a gaming console, an electronic dictionary, an electronic key, a camcorder, or an electronic picture frame. 
     According to an embodiment of the present disclosure, the electronic device may include at least one of various medical devices (e.g., diverse portable medical measuring devices (a blood sugar measuring device, a heartbeat measuring device, or a body temperature measuring device), a magnetic resource angiography (MRA) device, a magnetic resource imaging (MRI) device, a computed tomography (CT) device, an imaging device, or an ultrasonic device), a navigation device, a global navigation satellite system (GNSS) receiver, an event data recorder (EDR), a flight data recorder (FDR), an automotive infotainment device, an sailing electronic device (e.g., a sailing navigation device or a gyro compass), avionics, security devices, vehicular head units, industrial or home robots, drones, automatic teller machines (ATMs), point of sales (POS) devices, or Internet of things (IoT) devices (e.g., a light bulb, various sensors, a sprinkler, a fire alarm, a thermostat, a street light, a toaster, fitness equipment, a hot water tank, a heater, or a boiler). 
     According to various embodiments of the disclosure, examples of the electronic device may at least one of part of a piece of furniture, building/structure or vehicle, an electronic board, an electronic signature receiving device, a projector, or various measurement devices (e.g., devices for measuring water, electricity, gas, or electromagnetic waves). The electronic device may be flexible or may be a combination of the above-enumerated electronic devices. The electronic device is not limited to the above-listed embodiments. As used herein, the term “user” may denote a human or another device (e.g., an artificial intelligence electronic device) using the electronic device. 
     Referring to  FIG. 1 , according to an embodiment of the present disclosure, an electronic device  101  is included in a network environment  100 . The electronic device  101  includes a bus  110 , a processor  120 , a memory  130 , an input/output interface  150 , a display  160 , and a communication interface  170 . In some embodiments, the electronic device  101  may exclude at least one of the components or may add one or more other components. The bus  110  may include a circuit for connecting the components  110  to  170  with one another and transferring communications (e.g., control messages or data) between the components. The processor  120  may include one or more of a CPU, an AP, or a communication processor (CP). The processor  120  may control at least one of the other components of the electronic device  101 , and/or perform an operation or data processing relating to communication. 
     The memory  130  may include a volatile and/or non-volatile memory. For example, the memory  130  may store instructions or data related to at least one other component of the electronic device  101 . According to an embodiment of the present disclosure, the memory  130  may store software and/or a program  140 . The program  140  includes a kernel  141 , middleware  143 , an application programming interface (API)  145 , and/or an application program (or application)  147 . At least a portion of the kernel  141 , middleware  143 , or API  145  may be denoted an operating system (OS). For example, the kernel  141  may control or manage system resources (e.g., the bus  110 , the processor  120 , or the memory  130 ) used to perform operations or functions implemented in other programs (e.g., the middleware  143 , the API  145 , or the application  147 ). The kernel  141  may provide an interface that allows the middleware  143 , the API  145 , or the application  147  to access the individual components of the electronic device  101  to control or manage the system resources. 
     The middleware  143  may function as a relay to allow the API  145  or the application  147  to communicate data with the kernel  141 , for example. Further, the middleware  143  may process one or more task requests received from the application  147  in order of priority. For example, the middleware  143  may assign a priority of using system resources (e.g., the bus  110 , the processor  120 , or the memory  130 ) of the electronic device  101  to at least one of the applications  147  and process one or more task requests. The API  145  is an interface allowing the application  147  to control functions provided from the kernel  141  or the middleware  143 . For example, the API  133  may include at least one interface or function (e.g., a command) for filing control, window control, image processing or text control. For example, the input/output interface  150  may transfer instructions or data input from the user or other external device to other component(s) of the electronic device  101  or may output instructions or data received from other component(s) of the electronic device  101  to the user or other external devices. 
     The display  160  may include, for example, a liquid crystal display (LCD), a light emitting diode (LED) display, an organic light emitting diode (OLED) display, a microelectromechanical systems (MEMS) display, or an electronic paper display. The display  160  may display, for example, various contents (e.g., text, images, videos, icons, or symbols) to the user. The display  160  may include a touchscreen and may receive, for example, a touch, gesture, proximity or hovering input using an electronic pen or a body portion of the user. For example, the communication interface  170  may set up communication between the electronic device  101  and an external device (e.g., a first external device  102 , a second external device  104 , or a server  106 ). For example, the communication interface  170  may be connected with the network  162  through wireless or wired communication to communicate with the external device (e.g., the second external device  104  or the server  106 ). 
     The wireless communication may include cellular communication, which uses at least one of, for example, long term evolution (LTE), long term evolution-advanced (LTE-A), code division multiple access (CDMA), wideband code division multiple access (WCDMA), universal mobile telecommunication system (UMTS), wireless broadband (WiBro), and global system for mobile communication (GSM). According to an embodiment of the present disclosure, the wireless communication may include at least one of, for example, wireless-fidelity (Wi-Fi), light-fidelity (Li-Fi), bluetooth, bluetooth low power (BLE), zigbee, near-field communication (NFC), magnetic secure transmission (MST), radio frequency (RF), and body area network (BAN), as denoted by reference numeral  164  of  FIG. 1 . According to an embodiment of the present disclosure, the wireless communication may include global navigation satellite system (GNSS). The GNSS may be, for example, global positioning system (GPS), global navigation satellite system (Glonass), Beidou navigation satellite system (Beidou) or Galileo, or the European global satellite-based navigation system. Hereinafter, the terms “GPS” and “GNSS” may be interchangeably used. The wired connection may include at least one of, for example, universal serial bus (USB), high definition multimedia interface (HDMI), recommended standard (RS)-232, power line communication (PLC), and plain old telephone service (POTS). The network  162  may include at least one of telecommunication networks, for example, a computer network (e.g., local area network (LAN) or wide area network (WAN)), Internet, or a telephone network. 
     The first and second external devices  102  and  104  each may be a device of the same or a different type as/from the electronic device  101 . According to an embodiment of the present disclosure, all or some of operations executed on the electronic device  101  may be executed on another or multiple other electronic devices  102  and  104 , and/or the server  106 . According to an embodiment of the present disclosure, when the electronic device  101  should perform some function or service automatically or at a request, the electronic device  101 , instead of executing the function or service on its own, may request another device to perform at least some functions associated therewith. The other electronic device may execute the requested functions or additional functions and transfer a result of the execution to the electronic device  101 . The electronic device  101  may provide a requested function or service by processing the received result as it is or additionally. To that end, a cloud computing, distributed computing, or client-server computing technique may be used, for example. 
     According to an embodiment of the present disclosure, the components (e.g., the bus  110 , the processor  120 , the memory  130 , the input/output interface  150 , and/or the communication interface  170 ) of the electronic device  101  may be placed in the housing of the electronic device  101 , and at least some components (e.g., the display  160 ) may be provided on the housing. The components of the electronic device  101  may electrically be connected together. 
     According to an embodiment of the present disclosure, the memory  130  may store a plurality of codecs for processing audio data. The plurality of codecs may be used to process the audio data to stream the audio data to other electronic devices connected via bluetooth communication using the advanced audio distribution profile (A2DP). For example, the plurality of codecs may include a low complexity subband coding (SBC) codec, an MPEC-1 audio layer-3 (MP3) codec, an advanced audio coding (AAC) codec, an adaptive transform acoustic coding (ATRAC) codec, an aptX codec, or a scalable codec. 
     According to an embodiment of the present disclosure, the memory  130  may include instructions enabling the processor  120  to operate. For example, the memory  130  may include instructions enabling the processor  120  to control other components of the electronic device  101  and to interwork with other external devices  102  and  104  or the server  106 . The processor  120  may control other components of the electronic device  101  and interwork with the other external devices  102  and  104  or the server  106  based on the instructions stored in the memory  130 . Hereinafter, operations of the electronic device  101  are described based on each component of the electronic device  101 . The instructions enabling the components to operate may be stored in the memory  130 . 
     According to an embodiment of the present disclosure, the processor  120  may establish a first wireless channel and a second wireless channel with the first external device  102  and the second external device  104  using the communication interface  170 . For example, the first and second external devices  102  and  104  may be electronic devices supporting Bluetooth, for example, a headset and a speaker which are capable of playing audio. For example, the processor  120  may establish bluetooth connections with the first and second external devices  102  and  104  and establish the first and second wireless channels for transmitting audio data. 
     According to an embodiment of the present disclosure, the processor  120  may select one codec supported by the first and second external devices  102  and  104  from among the plurality of codecs stored in the memory  130 . The processor  120  may select one codec supported by the first and second external devices  102  and  104  while maintaining connections with the first and second external devices  102  and  104 . For example, the processor  120  may select one codec that both the first and second external devices  102  and  104  support among the plurality of codecs (e.g., an SBC codec, an MP3 codec, an AAC codec, an ATRAC codec, an aptX codec, or a scalable codec). 
     For example, in the operation of establishing the first and second wireless channels, the processor  120  may receive information about at least one codec that is supported by each of the first and second external devices  102  and  104  from the first and second external devices  102  and  104 . The processor  120  may identify at least one codec that both the first and second external devices  102  and  104  support of the plurality of codecs based on the received information. 
     For example, where only one of the plurality of codecs is supported by the first and second external devices  102  and  104 , the processor  120  may use the codec in processing (e.g., encoding) audio data for transmission to the first and second external devices  102  and  104 . 
     As another example, where multiple codecs of the plurality of codecs are supported by the first and second external devices  102  and  104 , the processor  120  may select one of the plurality of codecs that the first and second external devices  102  and  104  support based on the priorities of the plurality of codecs stored in the memory  130 . The processor  120  may use the selected codec in processing (e.g., encoding) audio data for transmission to the first and second external devices  102  and  104 . 
     For example, the priorities of the plurality of codecs may be designated based on at least one of the compression rate, degree of loss in sound quality due to compression, whether it is possible to vary the bit rate for transmitting audio data by controlling the compression rate, or perceptual evaluation audio quality (PEAQ). 
     According to an embodiment of the present disclosure, the processor  120  may process (e.g., encode) audio data using the selected one of the plurality of codecs. For example, the processor  120  may encode the audio data using the selected codec. 
     According to an embodiment of the present disclosure, the processor  120  may transmit the processed audio data through the first and second wireless channels to the first and second external devices  102  and  104  using the communication interface  170 . The first and second external devices  102  and  104  may receive the processed audio data, process (e.g., decode), and play the processed audio data with the same codec as the selected one. 
     As another example, one of the first and second external devices  102  and  104  may control functions related to the playback of audio data of the electronic device  101 . For example, the first and second external devices  102  and  104  may control the audio data playback-related functions of the electronic device  101 , such as, for example, starting or pausing the playback of audio data. 
     According to an embodiment of the present disclosure, the processor  120  may monitor the environment of the wireless channel. For example, the processor  120  may monitor the environment of the wireless channel with the data retransmission rate through the wireless channel. The following description focuses primarily on monitoring wireless channel environments with the data retransmission rate through the wireless channel. However, embodiments of the present disclosure are not limited thereto. Other methods are also available to monitor wireless channel environments. For example, the processor  120  may monitor the wireless channel environment through, for example, the presence or absence of data in the buffer for storing data to be transmitted through the wireless channel or flow control information received through the wireless channel. 
     According to an embodiment of the present disclosure, the processor  120  may control at least one of a first bit rate for transmitting the processed audio data through the first wireless channel or a second bit rate for transmitting the processed audio data through the second wireless channel based on the results of the monitoring. For example, the processor  120  may control the first bit rate based on at least one of a bit rate range designated for the selected codec or the second bit rate. The processor  120  may control the second bit rate based on at least one of a bit rate range designated for the selected codec or the first bit rate. 
     For example, the processor  120  may control at least one of the first bit rate or the second bit rate, controlling at least one of the transmission speed of the processed audio data through the first wireless channel or the transmission speed of the processed audio data through the second wireless channel. 
     For example, the processor  120  may compare a designated threshold with a first retransmission rate of the processed audio data through the first wireless channel or a second retransmission rate of the processed audio data through the second wireless channel. When the first retransmission rate or the second retransmission rate is not less than the designated threshold, the processor  120  may determine that the first or second wireless channel is in a poor condition, reducing the first bit rate and the second bit rate. The processor  120  may reduce both the first bit rate and the second bit rate, not only when the first retransmission rate and the second retransmission rate are not less than the designated threshold, but also when the first retransmission rate or the second retransmission rate is not less than the designated threshold 
     As another example, the processor  120  may reduce the first bit rate when the first retransmission rate is not less than the designated threshold. The processor  120  may reduce the first bit rate based on a designated bit rate range in the selected codec. The processor  120  may reduce the first bit rate within the designated bit rate range. The processor  120  may consider the second bit rate to determine the degree of reduction in the first bit rate. 
     As another example, the processor  120  may reduce the second bit rate when the second retransmission rate is not less than the designated threshold. The processor  120  may reduce the second bit rate based on a designated bit rate range in the selected codec. The processor  120  may reduce the second bit rate within the designated bit rate range. The processor  120  may consider the first bit rate to determine the degree of reduction in the second bit rate. 
     According to an embodiment of the present disclosure, the processor  120  may activate an operation mode for transmitting audio data to the first and second external devices  102  and  104  according to an input from a user. When the operation mode is activated, the processor  120  may display, through the display  160 , a graphical object to represent the activation of the operation mode. The processor  120  may display the graphical object in various forms depending on screens displayed through the display  160 . 
     For example, upon receipt of a user input to activate the operation mode, the processor  120  may select one codec, which the first and second external devices  102  and  104  support, from among the plurality of codecs. Before the operation mode is activated, the processor  120  may transmit audio data to only one of the first and second external devices  102  and  104  although it is connected with the first and second external devices  102  and  104 . 
     As another example, the processor  120  is connected with only the first external device  102 , and as it is connected to the second external device  104  in the activated state of the operation mode, the processor  120  may select one codec that the first and second external devices support  102  and  104 . 
     According to an embodiment of the present disclosure, the processor  120  may deactivate the operation mode, which is active according to a user input. When the operation mode is deactivated, the processor  120  may perform control so that the graphical object is not displayed through the display  160 . 
     For example, when the operation mode is deactivated, the processor  120  may transmit audio data to only one of the first and second external devices  102  and  104 . The processor  120  may select one to which to transmit audio data between the first and second external devices  102  and  104 . The processor  120  may select the device to which to transmit audio data according to a user input or order of connection to the first and second external devices  102  and  104 . For example, the external device selected by the user, the external device connected before the operation mode is activated, or the external device after the operation mode is activated, may be selected. 
     For example, the processor  120  may process (e.g., encode) audio data using a codec supported by the selected external device among the plurality of codecs. The codec supported by the selected external device may be a codec that has been used to transmit audio data to the selected external device before the operation mode is activated or a codec with a higher priority among the codecs supported by the selected external device. The codec supported by the selected external device may be the same or different from the codec that has been used to transmit audio data while the operation mode is active. 
     For example, the processor  120  may transmit the processed audio data to the selected electronic device. The processor  120  may restrict transmission of the processed audio data to the external device not selected among the first and second external devices  102  and  104 . 
       FIG. 2  is a block diagram illustrating an electronic device  201  according to an embodiment of the present disclosure. The electronic device  201  includes one or more processors (e.g., APs)  210 , a communication module  220 , a subscriber identification module (SIM)  224 , a memory  230 , a sensor module  240 , an input device  250 , a display  260 , an interface  270 , an audio module  280 , a camera module  291 , a power management module  295 , a battery  296 , an indicator  297 , and a motor  298 . The processor  210  may control multiple hardware and software components connected to the processor  210  by running, for example, an OS or APs, and the processor  210  may process and compute various data. The processor  210  may be implemented in, for example, a system on chip (SoC). The processor  210  may further include a graphic processing unit (GPU) and/or an image signal processor. The processor  210  may include at least some of the components shown in  FIG. 2  (e.g., a cellular module  221 ). The processor  210  may load a command or data received from at least one of other components (e.g., a non-volatile memory) on a volatile memory, process the command or data, and store resultant data in the non-volatile memory. 
     The communication module  220  may have the same or a similar configuration as the communication interface  170 . The communication module  220  includes the cellular module  221 , a wireless fidelity (Wi-Fi) module  223 , a bluetooth (BT) module  225 , a GNSS module  227 , a NFC module  228 , and a RF module  229 . The cellular module  221  may provide voice call, video call, text, or Internet services through a communication network. According to an embodiment of the present disclosure, the cellular module  221  may perform identification or authentication on the electronic device  201  in the communication network using a SIM  224  (e.g., a SIM card). The cellular module  221  may perform at least some of the functions provided by the processor  210 . The cellular module  221  may include a CP. At least some (e.g., two or more) of the cellular module  221 , the Wi-Fi module  223 , the Bluetooth module  225 , the GNSS module  227 , or the NFC module  228  may be included in a single integrated circuit (IC) or an IC package. The RF module  229  may communicate data, such as, for example, communication signals (e.g., RF signals). The RF module  229  may include, for example, a transceiver, a power amp module (PAM), a frequency filter, a low noise amplifier (LNA), or an antenna. At least one of the cellular module  221 , the Wi-Fi module  223 , the bluetooth module  225 , the GNSS module  227 , or the NFC module  228  may communicate RF signals through a separate RF module. The SIM  224  may include, for example, a card including a SIM, or an embedded SIM, and may contain unique identification information (e.g., an integrated circuit card identifier (ICCID)) or subscriber information (e.g., an international mobile subscriber identity (IMSI)). 
     The memory  230  includes an internal memory  232  and/or an external memory  234 . The internal memory  232  may include at least one of, for example, a volatile memory (e.g., a dynamic RAM (DRAM), a static RAM (SRAM), a synchronous dynamic RAM (SDRAM), etc.) or a non-volatile memory (e.g., a one-time programmable ROM (OTPROM), a programmable ROM (PROM), an erasable and programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a mask ROM, a flash ROM, a flash memory (e.g., a NAND flash, or a NOR flash), a hard drive, or solid-state drive (SSD)). The external memory  234  may include a flash drive, such as, for example, a compact flash (CF) memory, a secure digital (SD) memory, a micro-SD memory, a min-SD memory, an extreme digital (xD) memory, a multi-media card (MMC), or a memory stick. The external memory  234  may be functionally or physically connected with the electronic device  201  via various interfaces. 
     The sensor module  240  may measure a physical quantity or detect a motion state of the electronic device  201 , and the sensor module  240  may convert the measured or detected information into an electrical signal. The sensor module  240  includes at least one of a gesture sensor  240 A, a gyro sensor  240 B, an atmospheric pressure sensor  240 C, a magnetic sensor  240 D, an acceleration sensor  240 E, a grip sensor  240 F, a proximity sensor  240 G, a color sensor  240 H (e.g., a red-green-blue (RGB) sensor), a bio sensor  240 I, a temperature/humidity sensor  240 J, an illumination sensor  240 K, and an ultra violet (UV) sensor  240 M. Additionally or alternatively, the sensing module  240  may include an e-nose sensor, an electromyography (EMG) sensor, an electroencephalogram (EEG) sensor, an electrocardiogram (ECG) sensor, an infrared (IR) sensor, an iris sensor, or a finger print sensor. The sensor module  240  may further include a control circuit for controlling one or more of the sensors included in the sensing module. According to an embodiment of the present disclosure, the electronic device  201  may further include a processor configured to control the sensor module  240  as part of the processor  210  or separately from the processor  210 , and the electronic device  201  may control the sensor module  240  while the processor  210  is in a sleep mode. 
     The input unit  250  includes at least one of a touch panel  252 , a (digital) pen sensor  254 , a key  256 , and an ultrasonic input device  258 . The touch panel  252  may use at least one of capacitive, resistive, infrared, or ultrasonic methods. The touch panel  252  may further include a control circuit. The touch panel  252  may further include a tactile layer and may provide a user with a tactile reaction. The (digital) pen sensor  254  may include, e.g., a part of a touch panel or a separate sheet for recognition. The key  256  may include e.g., a physical button, an optical key, or a key pad. The ultrasonic input device  258  may sense an ultrasonic wave generated from an input tool through a microphone  288  to identify data corresponding to the sensed ultrasonic wave. 
     The display  260  includes at least one of a panel  262 , a hologram device  264 , a projector  266 , and a control circuit for controlling the same. The panel  262  may be implemented to be flexible, transparent, or wearable. The panel  262 , together with the touch panel  252 , may be configured in one or more modules. According to an embodiment of the present disclosure, the panel  262  may include a pressure sensor (or force sensor) that may measure the strength of a pressure by the user&#39;s touch. The pressure sensor may be implemented in a single body with the touch panel  252  or may be implemented in one or more sensors separate from the touch panel  252 . The hologram device  264  may make three dimensional (  3  D) images (holograms) in the air by using light interference. The projector  266  may display an image by projecting light onto a screen. The screen may be, for example, located inside or outside of the electronic device  201 . 
     The interface  270  includes at least one of a high definition multimedia interface (HDMI)  272 , a USB  274 , an optical interface  276 , or a D-subminiature (D-sub)  278 . The interface  270  may be included in the communication interface  170  shown in  FIG. 1 . Additionally or alternatively, the interface  270  may include a mobile high-definition link (MHL) interface, a secure digital (SD) card/multimedia card (MMC) interface, or Infrared Data Association (IrDA) standard interface. 
     The audio module  280  may convert a sound signal into an electrical signal and vice versa. At least a part of the audio module  280  may be included in the input/output interface  145  of  FIG. 1 . The audio module  280  may process sound information input or output through a speaker  282 , a receiver  284 , an earphone  286 , or the microphone  288 . 
     The camera module  291  is a device for capturing still images and videos, and may include, according to an embodiment of the present disclosure, one or more image sensors (e.g., front and back sensors), a lens, an image signal processor (ISP), or a flash, such as an LED or xenon lamp. 
     The power manager module  295  may manage power of the electronic device  201 , for example. According to an embodiment of the present disclosure, the power manager module  295  may include a power management Integrated circuit (PMIC), a charger IC, or a battery gauge. The PMIC may have a wired and/or wireless recharging scheme. The wireless charging scheme may include e.g., a magnetic resonance scheme, a magnetic induction scheme, or an electromagnetic wave based scheme, and an additional circuit, such as a coil loop, a resonance circuit, a rectifier, or the like may be added for wireless charging. 
     The battery gauge may measure an amount of remaining power of the battery  296 , a voltage, a current, or a temperature while the battery  296  is being charged. The battery  296  may include, e.g., a rechargeable battery or a solar battery. 
     The indicator  297  may indicate a particular state of the electronic device  201  or a part (e.g., the processor  210 ) of the electronic device, including, for example, a booting state, a message state, or recharging state. 
     The motor  298  may convert an electric signal to a mechanical vibration and may generate a vibrational or haptic effect. 
     The electronic device  201  may include a mobile TV supporting device (e.g., a GPU) that may process media data as per, e.g., digital multimedia broadcasting (DMB), digital video broadcasting (DVB), or mediaFlo™ standards. 
     Each of the aforementioned components of the electronic device may include one or more parts, and a name of the part may vary with a type of the electronic device. According to various embodiments, the electronic device  201  may exclude some noted elements or include additional elements, or some of the elements may be combined into a single entity that may perform the same function as by the elements before combined. 
       FIG. 3  is a block diagram illustrating a program module, according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, a program module  310  may include an OS) controlling resources related to the electronic device  101  and/or various applications  147  driven on the operating system. Referring to  FIG. 3 , the program module  310  includes a kernel  320 , middleware  330 , an API  360 , and/or an application  370 . At least a part of the program module  310  may be preloaded on the electronic device or may be downloaded from an external device. 
     The kernel  320  may include, for example, a system resource manager  321  and/or a device driver  323 . The system resource manager  321  may perform control, allocation, or recovery of system resources. According to an embodiment of the present disclosure, the system resource manager  321  may include a process managing unit, a memory managing unit, or a file system managing unit. The device driver  323  may include, for example, a display driver, a camera driver, a bluetooth driver, a shared memory driver, a USB driver, a keypad driver, a Wi-Fi driver, an audio driver, or an inter-process communication (IPC) driver. The middleware  330  may provide various functions to the application  370  through the API  360  so that the application  370  may use limited system resources in the electronic device or provide functions jointly required by applications  370 . The middleware  330  includes at least one of a runtime library  335 , an application manager  341 , a window manager  342 , a multimedia manager  343 , a resource manager  344 , a power manager  345 , a database manager  346 , a package manager  347 , a connectivity manager  348 , a notification manager  349 , a location manager  350 , a graphic manager  351 , or a security manager  352 . 
     The runtime library  335  may include a library module used by a compiler in order to add a new function through a programming language while the application  370  is being executed. The runtime library  335  may perform input/output management, memory management, or arithmetic function processing. The application manager  341  may manage the life cycle of the applications  370 . The window manager  342  may manage GUI resources used on the screen. The multimedia manager  343  may grasp formats necessary to play media files and use a codec appropriate for a format to perform encoding or decoding on media files. The resource manager  344  may manage the source code or memory space of the application  370 . The power manager  345  may manage the capacity, temperature, or power of the battery, and determine and provide power information necessary for the operation of the electronic device using a corresponding piece of information of such. According to an embodiment of the present disclosure, the power manager  345  may interwork with a basic input/output system (BIOS). The database manager  346  may generate, search, or vary a database to be used in the applications  370 . The package manager  347  may manage installation or update of an application that is distributed in the form of a package file. 
     The connectivity manager  348  may manage wireless connectivity. The notification manager  349  may provide an event, such as, for example, an arrival message, an appointment, or a proximity alert, to the user. The location manager  350  may manage locational information on the electronic device. The graphic manager  351  may manage graphic effects to be offered to the user and their related user interface. The security manager  352  may provide system security or user authentication, for example. According to an embodiment of the present disclosure, the middleware  330  may include a telephony manager for managing the voice or video call function of the electronic device or a middleware module able to form a combination of the functions of the above-described elements. The middleware  330  may provide a module specified according to the type of the operating system. The middleware  330  may dynamically omit some existing components or add new components. 
     The API  360  may be a set of API programming functions and may have different configurations depending on operating systems. For example, in the case of Android or iOS, one API set may be provided per platform, and in the case of Tizen, two or more API sets may be offered per platform. 
     The application  370  provides, for example, a home  371 , a dialer  372 , an SMS/MMS  373 , an instant message (IM)  374 , a browser  375 , a camera  376 , an alarm  377 , a contact  378 , a voice dial  379 , an email  380 , a calendar  381 , a media player  382 , an album  383 , or a clock  384 , a heath-care (e.g., measuring the degree of workout or blood sugar), or provision of environmental information (e.g., provision of air pressure, moisture, or temperature information). According to an embodiment of the present disclosure, the application  370  may include an information exchanging application supporting information exchange between the electronic device and an external device. Examples of the information exchange application may include, but is not limited to, a notification relay application for transferring specific information to the external device, or a device management application for managing the external device. For example, the notification relay application may transfer notification information generated by another application of the electronic device to the external device, or receive notification information from the external device and provide the received notification information to the user. For example, the device management application may install, delete, or update a function (e.g., turn-on/turn-off the external device (or some elements) or adjusting the brightness (or resolution) of the display) of the external device communicating with the electronic device or an application operating on the external device. The application  370  may include an application (e.g., a health-care application of a mobile medical device) designated according to an attribute of the external device. The application  370  may include an application received from the external device. At least a portion of the program module  310  may be implemented (e.g., executed) in software, firmware, hardware (e.g., the processor  210 ), or a combination of at least two or more thereof and may include a module, program, routine, command set, or process for performing one or more functions. 
       FIG. 4  is a flowchart illustrating a method for transmitting audio data by an electronic device, according to an embodiment of the present disclosure. 
     In operation  410 , a processor  120  of the electronic device  101  establishes a first wireless channel with a first external device using a wireless communication circuit (e.g., the communication interface  170 ). For example, in the operation of establishing the first wireless channel with the first external device, the processor may receive information about a codec (e.g., an aptX codec or SBC codec) supported by the first external device using the wireless communication circuit. 
     In operation  420 , the processor establishes a second wireless channel with a second external device using the wireless communication circuit. For example, in the operation of establishing the second wireless channel with the second external device, the processor may receive information about a codec (e.g., a scalable codec or SBC codec) supported by the second external device using the wireless communication circuit. 
     In operation  430 , the processor selects one codec supported by the first and second external devices from among a plurality of codecs stored in a memory  130  of the electronic device  101 . For example, the processor may display, on a display  160 , a screen for activating an operation mode (e.g., a dual audio mode) to transmit audio data to the first and second external devices. The screen may be displayed according to a user input or as the second wireless channel with the second external device is established. According to the receipt of an input to activate the operation mode while the screen is displayed, the processor may activate the operation mode and select one codec that the first and second external devices support. 
     As another example, the processor is connected with only the first external device, and as it is connected to the second external device in the activated state of the operation mode, the processor may select one codec that the first and second external devices support. 
     For example, the processor may identify at least one codec supported by the first and second external devices among the plurality of codecs based on the information about the codec supported by the first and second external devices, which is received from the first and second external devices, and the processor may select a codec for processing (e.g., encoding) audio data. For example, the processor may select the SBC codec supported by the first and second external devices as a codec for processing audio data in the operation mode based on the received information. 
     In operation  440 , the processor processes (e.g., encodes) audio data using the selected codec. For example, the processor may process the audio data using the selected SBC codec. 
     In operation  450 , the processor transmits the processed audio data to the first and second external devices through the first and second wireless channels using the wireless communication circuit. For example, the first and second external devices may receive the processed audio data, process (e.g., decode), and play the processed audio data with the same codec (e.g., an SBC codec). 
       FIG. 5  is a flowchart illustrating a method for selecting a codec to process (e.g., encode) audio data by an electronic device, according to an embodiment of the present disclosure. 
     In operation  510 , a processor  120  of the electronic device  101  may identify at least one codec commonly supported by a first external device and a second external device among at least one codec that each of the first and second external devices supports based on information about the at least one codec that is received from the first and second external devices. 
     In operation  520 , the processor determines whether a plurality of codecs are commonly supported by the first and second external devices. When a plurality of codecs are supported, the processor needs to select one for processing audio data among the plurality of codecs that the first and second external devices support. Thus, the processor needs to determine whether a plurality of codecs are commonly supported by the first and second external devices. 
     When a plurality of codecs are commonly supported by the first and second external devices, in operation  530 , the processor selects one of the plurality of codecs commonly supported by the first and second external devices based on the priorities of the plurality of codecs stored in a memory  130  of the electronic device  101 . 
     For example, the priorities of the plurality of codecs may be designated based on at least one of the compression rate, degree of loss in sound quality due to compression, whether it is possible to vary the bit rate for transmitting audio data by controlling the compression rate, or PEAQ. 
     For example, when the memory stores a scalable codec, an AAC codec, and an SBC codec, the respective priorities of the scalable codec, AAC codec, and SBC codec may be designated as shown in Table 1 below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 priority 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1 
                 Scalable codec 
               
               
                 2 
                 AAC codec 
               
               
                 3 
                 SBC codec 
               
               
                   
               
            
           
         
       
     
     However, this is merely for description purposes, and embodiments of the present disclosure are not limited thereto. For example, the priorities of the plurality of codecs may differ from those shown in Table  1  depending on criteria for designating priority. 
     For example, where the scalable codec and the SBC codec are identified as commonly supported by the first and second external devices, and their respective priorities are designated as shown in Table 1, the processor may select the scalable codec. 
     In operation  540 , the processor processes (e.g., encodes) audio data using the codec selected based on priority among the plurality of codecs. For example, the processor may encode the audio data using the selected scalable codec. 
     When two or more codecs commonly supported by the first and second external devices are not identified in operation  520 , the processor processes (e.g., encodes) audio data using the one identified codec, in operation  550 . For example, when only the SBC codec is commonly supported by the first and second external devices, the processor may encode audio data using the SBC codec. 
       FIG. 6  is a flowchart illustrating a method for operating an electronic device after deactivating an operation mode for transmitting audio data to multiple external devices, according to an embodiment of the present disclosure. 
     In operation  610 , a processor  120  of the electronic device  101  deactivates an operation mode (e.g., a dual audio mode) for transmission of audio data to first and second external devices according to a user input. 
     In operation  620 , when the operation mode is deactivated, the processor selects one of the first and second external devices to which to transmit audio data. When the operation mode is deactivated, the processor may transmit audio data to only one external device. According to an embodiment of the present disclosure, the processor may select the external device to which to transmit audio data according to a user input, order of connection to the first and second external devices, or ambient environment. For example, the external device selected by the user, the external device connected before the operation mode is activated, or the external device after the operation mode is activated may be selected. 
     For example, when each of the first and second external devices is connected before the operation mode is activated, the processor may select the external device connected later of the first and second external devices as the external device to which to transmit audio data, according to order of connection. As another example, the processor may select the external device connected first of the first and second external devices as the external device to which to transmit audio data, according to order of connection to the first and second external devices. 
     For example, when the first external device is connected before the operation mode is activated, while the second external device is connected after the operation mode is activated, the processor may select the second external device connected after the operation mode is activated as the external device to which to transmit audio data, according to order of connection. As another example, the processor may select the first external device connected before the operation mode is activated as the external device to which to transmit audio data according to order of connection. 
     For example, when the first and second external devices are connected after the operation mode is activated, the processor may select the external device connected later of the first and second external devices as the external device to which to transmit audio data, according to order of connection. As another example, the processor may select the external device connected first of the first and second external devices as the external device to which to transmit audio data, according to order of connection. 
     As another example, when the operation mode is deactivated, the processor may select one of the first and second external devices to which to transmit audio data according to the ambient environment. For example, when a designated number of people or more are determined to be positioned around the electronic device  101  by at least one sensor of the sensor module  240 , a camera of the camera module  291 , or a microphone  288  of the electronic device  101 , the processor may select an external device (e.g., a speaker) playing audio data for a number of people to listen to the audio as the external device to which to transmit audio data. As another example, when a designated number of people or more are determined to be positioned around the electronic device  101  by at least one sensor of the sensor module  240  or a communication interface  170 , the processor may select an external device (e.g., a speaker) playing audio data for a number of people to listen to the audio as the external device to which to transmit audio data. 
     In operation  630 , the processor determines whether a first codec used to transmit audio data while the operation mode is active is the same as a second codec to be used to transmit audio data to a selected electronic device. After an external device to which to transmit audio data is selected, the processor may select the second codec to be used to transmit audio data to the selected external device among codecs supported by the selected external device. 
     For example, the second codec may be selected as the codec that has been used to transmit audio data to the selected external device before the operation mode (e.g., a dual audio mode) is activated, among the codecs that the selected external device supports. For example, when the selected external device supports an AAC codec, a scalable codec, and an SBC codec, the AAC codec is used as the first codec, and the scalable codec is used before the operation mode is activated, the processor may select the scalable codec as the second codec. As another example, the processor may select, as the second codec, the other codec, i.e., the SBC codec, than the scalable codec which has been used before the operation mode is activated and the first codec among the codecs that the selected external device supports. 
     As another example, when the selected external device is connected after the operation mode (e.g., a dual audio mode) is activated, the second codec may be selected as one with a higher priority among the codecs that the selected external device supports. For example, when the selected external device is connected after the operation mode is activated, the processor may select the scalable codec as the second codec based on the priorities shown in Table 1. 
     According to an embodiment of the present disclosure, the processor may determine whether the first codec is the same as the second codec to determine whether changing codecs is needed to transmit audio data to the selected external device. 
     When the first codec is the same as the second codec, the processor processes (e.g., encodes) audio data with the first codec, in operation  640 . For example, when the first codec is the same as the second codec, the processor may keep processing audio data with the first codec without changing codecs for processing (e.g., encoding) audio data. For example, when the first codec is the AAC codec, and the AAC codec is selected as the second codec among the codecs the selected external device supports, the processor may continue to use the AAC codec to process audio data without changing codecs for processing audio data. 
     When the first codec differs from the second codec, the processor changes codecs for processing (e.g., encoding) audio data, in operation  650 . For example, when the first codec is different from the second codec, the processor may change the codec for processing audio data from the first codec to the second codec. For example, where the first codec is the AAC codec, and the scalable codec or SBC codec is selected as the second codec among the codecs the selected external device supports, the processor may change the codec for processing audio data from the AAC codec to the scalable codec or SBC codec. 
     Bluetooth communication is conducted within a limited frequency band, and is thus subject to a limitation in the amount of data transmitted. For example, the amount of data transmitted from the electronic device to only one electronic device that the electronic device connects to may be larger than the amount data transmitted from the electronic device to each of multiple external devices that the electronic device connects to. Thus, where data is transmitted to only one device, the processor may use a codec that causes less quality deterioration to present better sound quality although the data volume transmitted is increased due to the reduced compression rate. 
     For example, since audio data is transmitted to only one external device before the operation mode is activated, a low quality-loss codec may be used as the second codec despite an increase in the data volume transmitted due to the reduced compression rate. Since audio data is transmitted to multiple external devices while the operation mode is active, a codec that has a higher compression rate than the second codec with the result of relatively more quality loss may be used as the first codec. Thus, where the first codec is different from the second codec, the processor may change the codec for transmitting audio data from the first codec to the second codec. 
     For example, changing codecs for processing audio data may be done using an interval when the playback of audio data pauses to prevent sound drops. For example, the processor may perform the codec change during an interval when the playback of audio data pauses, such as, for example, when the playback of audio data pauses as a switch occurs in the audio playback list, when the playback of audio data pauses as an application (e.g., a call application, video application, or broadcast application) runs, or when the user pauses the playback of audio data. 
     In operation  660 , the processor processes (e.g., encodes) audio data with the changed second codec. For example, where the codec for processing audio data is changed to the scalable codec, the processor may encode audio data using the scalable codec. 
     As another example, even when the first codec differs from the second codec, the processor may keep using the first codec to process audio data without changing codecs according to the user&#39;s choice. 
       FIG. 7  is a diagram illustrating a method for transmitting audio data to multiple external devices by an electronic device, according to an embodiment of the present disclosure. 
     Referring to  FIG. 7 , for example, a first external device may support an aptX codec and an SBC codec, a second external device may support a scalable codec and the SBC codec, and the electronic device  101  may support the aptX codec, the scalable codec, and the SBC codec. For example, the respective priorities of the aptX codec, the scalable codec, and the SBC codec may be shown in Table 2 below. 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 priority 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1 
                 Scalable codec 
               
               
                 2 
                 aptX codec 
               
               
                 3 
                 SBC codec 
               
               
                   
               
            
           
         
       
     
     However, this is merely for description purposes, and embodiments of the present disclosure are not limited thereto. For example, the priorities of the plurality of codecs may differ from those shown in Table 2 depending on criteria for designating priority. 
     Referring to  FIG. 7 , for example, the function (e.g., dual audio) of transmitting audio data to multiple external devices may be inactive during the time interval from t 0  to t 2  and after t 3 , and the function of transmitting audio data to multiple external devices may be active only during the time interval from t 2  to t 3 . 
     As another example, referring to  FIG. 7 , while the electronic device  101  is active during the time interval between t 0  and t 5 , the electronic device  101  may be connected with only the first external device during the time interval between t 0  and t 1 , with only the second external device during the time interval between t 1  and t 2 , with both the first external device and the second external device during the time interval between t 2  and t 3 . After t 3 , the electronic device  101  may be disconnected from the first external device, remaining connected with only the second external device. 
     For example, during the time interval between t 0  and t 1 , the electronic device  101  may be configured to transmit audio data to the first external device, and a processor  120  of the electronic device  101  may process (e.g., encode) audio data using the aptX codec which is selected based on the priorities between the aptX codec and the SBC codec the first external device supports, and the processor may transmit the processed audio data to the first external device using a wireless communication circuit (e.g., the communication interface  170 ). The first external device may process (e.g., decode) the received audio data using the selected aptX codec. 
     During the time interval between ti and t  2 , the electronic device  101  may be configured to transmit audio data to the second external device, and the processor may process (e.g., encode) audio data using the scalable codec which is selected based on the priorities between the scalable codec and the SBC codec the second external device supports, and the processor may transmit the processed audio data to the second external device using the wireless communication circuit. The second external device may process (e.g., decode) the received audio data using the selected scalable codec. 
     As such, during the time interval between t 0  and t 2  when the electronic device is connected with only one of the first and second external devices, or when the function of transmitting audio data to the first and second external devices is inactive, the processor may transmit audio data to only one of the first and second external devices using the wireless communication circuit. 
     For example, where the function is activated or the electronic device is connected with both the first and second external devices in the active state of the function at t 2 , the processor may select the SBC codec that is a codec commonly supported by the first and second external devices among the aptX codec, the scalable codec, and the SBC codec. During the time interval between t 2  and t 3 , when the electronic device is connected with both the first and second external devices in the activated state of the function or the function is activated, the processor may process (e.g., encode) audio data using the SBC codec and transmit the processed audio data to the first and second external devices using the wireless communication circuit. The first and second external devices may process (e.g., decode) the received audio data using the selected SBC codec. 
     For example, when the function is deactivated at t 3 , the processor may select the second external device between the first and second external devices. As the second external device is selected, the processor may restrict the transmission of the processed audio data to the first external device while transmitting audio data to only the second external device selected. 
     As another example, even when the function is not deactivated, the processor may transmit audio data to only the second external device when the first external device powers off, or when sensing a disconnection from the first external device. 
     The processor may process audio data using the SBC codec that had been used during the time interval between t 3  to t 4  and transmit the processed audio data to the second external device using the wireless communication circuit. 
     Since the scalable codec used during the time interval between t 1  and t 2  differs from the SBC codec used during the time interval between t 3  and t 4 , the processor may change codecs for processing audio data. For example, the processor may negotiate with the second external device to change codecs. To change codecs, the processor may provide information about the changed codec to the second external device, and the second external device may accept the codec change based on the information about the changed codec. 
     During the time interval between t 4  and t 5 , the processor may pause the transmission of audio data to change codecs for processing audio data. For example, to prevent sound drops, the processor may change the codec for processing audio data from the SBC codec to the scalable codec during the time interval between t 4  and t 5  when the playback of audio data pauses. For example, the processor may perform the codec change during an interval when the playback of audio data pauses, such as, for example, when the playback of audio data pauses as a switch occurs in the audio playback list, when the playback of audio data pauses as an application (e.g., a call application, a video application, or a broadcast application) runs, or when the user pauses the playback of audio data. 
     After t 5 , the processor may process audio data using the scalable codec and transmit the processed audio data to the second external device using the wireless communication circuit. 
       FIG. 8A  is a diagram illustrating a screen for setting an operation mode to transmit audio data to multiple external devices, which is displayed on an electronic device, according to an embodiment of the present disclosure. 
     According to an embodiment of the present disclosure, a processor  120  of the electronic device  101  may display, through a display  160 , a screen for setting an operation mode (e.g., a dual audio mode) for transmitting audio data to multiple external devices, as shown in  FIG. 8A . For example, a description of the operation mode or a method for using the operation mode may be provided through the screen. For example, the processor may activate or deactivate the operation mode according to a user input that is received while the screen is displayed. 
     According to an embodiment of the present disclosure, the processor may activate or deactivate the operation mode according to a user input that is received even when the screen is displayed. For example, although not shown, the operation mode may be activated or deactivated based on the user&#39;s gesture or an input to an indicator (or status bar), quick panel, or icon displayed on at least part of the display. 
       FIG. 8B  is a diagram illustrating a home screen in a state where an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure. 
     According to an embodiment of the present disclosure, a processor  120  of the electronic device  101  may display a graphical object  810  on a status bar at an upper end to represent the activated state of an operation mode (e.g., a dual audio mode) to transmit audio data to multiple external devices while a home screen is displayed as shown in (a) of  FIG. 8B . The user may easily notice the activated state of the operation mode through the graphical object  810  displayed on the status bar. According to an embodiment of the present disclosure, the graphical object  810  may be displayed differently based on the type of the external device (e.g., a speaker, earphone, headset, or smartphone). According to an embodiment of the present disclosure, the processor may release the connection with one electronic device based on a user input (e.g., a touch or pressed touch) to the graphical object  810 . 
     According to an embodiment of the present disclosure, as shown in (b) of  FIG. 8B , the processor may display a graphical object  811  on the status bar at the upper end to represent that the operation mode is in the active state while the home screen is in display. The user may easily notice the activated state of the operation mode through the graphical object  811  displayed on the status bar. According to an embodiment of the present disclosure, the processor may release the connection with one electronic device based on a user input to the graphical object  811 . According to an embodiment of the present disclosure, the graphical object  811  may be displayed in various forms to represent the activation of the operation mode. 
     According to an embodiment of the present disclosure, although not shown, where the operation mode is activated, and the electronic device is connected with the plurality of external devices, the processor may display a plurality of graphical objects on the status bar to represent that the electronic device is connected with each of the plurality of external devices via bluetooth communication. 
       FIG. 8C  is a diagram illustrating a standby screen and a lock screen in a state where an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure. 
     According to an embodiment of the present disclosure, a processor  120  of the electronic device  101  may display a graphical object  820  to represent the activated state of an operation mode (e.g., a dual audio mode) to transmit audio data to multiple external devices while a standby screen is displayed as shown in (a) of  FIG. 8C . The user may easily notice the activated state of the operation mode through the graphical object  820  displayed on the standby screen even without releasing the standby screen. As another example, the graphical object  820  may always be displayed on the standby screen as is information to display the date, time, and battery status, or a graphical object to indicate receipt of messages. 
     According to an embodiment of the present disclosure, the processor may release the connection with one electronic device based on a user input (e.g., a touch or pressed touch) to the graphical object  820 . 
     According to an embodiment of the present disclosure, as shown in (b) of  FIG. 8C , the processor may display a graphical object  821  to represent that the operation mode is in the active state while the lock screen is in display. The user may easily notice the activated state of the operation mode through the graphical object  821  displayed on the lock screen even without releasing the lock screen. 
     According to an embodiment of the present disclosure, the processor may release the connection with one electronic device based on a user input to the graphical object  821 . 
       FIG. 8D  is a diagram illustrating a status bar that is expanded depending on whether an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure. 
     According to an embodiment of the present disclosure, a processor  120  may display an expanded status bar according to a user input in the state that an operation mode (e.g., a dual audio mode) for transmitting audio data to a plurality of external devices is not active, as shown in (a) of  FIG. 8D . The processor may display the plurality of external devices wirelessly connected with the electronic device  101  through the status bar. The processor may display an external device (e.g., a speaker) that plays audio data among the plurality of connected external devices to come to the user&#39;s notice through the expanded status bar. 
     As another example, the processor may display a menu  830  for selecting a device to play audio data among the plurality of connected external devices and the electronic device  101  through the expanded status bar. The processor may change devices to play audio data according to a user input. For example, when a headset is selected as the device to play audio data according to a user input while audio data is played through a speaker wirelessly connected with the electronic device  101 , the processor may transmit the audio data to the headset. As another example, when the electronic device  101  is selected as the device to play audio data according to a user input, the processor may play audio data through the speaker of the electronic device  101 . 
     According to an embodiment of the present disclosure, the processor may display the expanded status bar according to a user input while the operation mode is active, as shown in (b) of  FIG. 8D . The processor may display external devices wirelessly connected with the electronic device  101  through the expanded status bar. The processor may display a plurality of external devices to play audio data as the operation mode is activated among the plurality of external devices wirelessly connected in such a manner that the user may notice through the expanded status bar. 
     As another example, when the operation mode is activated, the processor may display a menu  840  for selecting a device to play audio data among the plurality of connected external devices and the electronic device  101  through the expanded status bar. The processor may change devices to play audio data according to a user input. 
     As another example, the processor may display a menu  841  for displaying a screen (e.g., the screen shown in  FIG. 8A ) to set the operation mode and a message  842  to indicate that the operation mode has been activated through the expanded status bar. For example, the processor may display the screen (e.g., the screen shown in  FIG. 8A ) for setting the operation mode or deactivate the operation mode based on a user input (e.g., a touch or pressed touch) to the menu  841 . 
       FIG. 8E  is a diagram illustrating a volume control screen in a state where an operation mode for transmitting audio data to multiple external devices is activated, which is displayed on an electronic device, according to an embodiment of the present disclosure. 
     According to an embodiment of the present disclosure, a processor  120  of the electronic device  101  may display a screen for adjusting the volume of audio data transmitted to a plurality of external devices according to a user input for adjusting sound volume while an operation mode for transmitting audio data to the plurality of external devices is active, as shown in  FIG. 8E . The processor may simultaneously adjust the sound volume of audio data transmitted to each of the plurality of external devices according to a user input. As another example, the processor may adjust the sound volume of only the audio data transmitted to one of the plurality of external devices according to a user input. 
       FIG. 9  is a diagram illustrating a method for setting an operation mode for transmitting audio data from an electronic device to multiple external devices, according to an embodiment of the present disclosure. 
     Referring to (a) of  FIG. 9 , a processor  120  of the electronic device  101  may display, on a screen for bluetooth connection, a menu including an item for entry into an operation mode configuration screen for transmitting audio data to a plurality of external devices, as shown in  FIG. 8A . 
     For example, upon receipt of a user input  910  for selecting the item from the menu, the processor may display the operation mode configuration screen as shown in (b) of  FIG. 9 . 
     According to an embodiment of the present disclosure, the processor may determine whether the plurality of external devices support a media volume synchronization function to determine whether the media volume synchronization function is to be used in the operation mode. 
     For example, when the media volume synchronization function is used in the operation mode, the processor may fix the volume of the electronic device  101  to the maximum so that the audio data played at the maximum volume fixed may be transmitted to the plurality of external devices. The external devices supporting the media volume synchronization function may control the volume of the playing audio data using the media volume synchronization function. However, the other external devices not supporting the media volume synchronization function cannot control the volume of audio data, so that the volume of the playing audio may be too high. 
     For example, when at least one of the plurality of external devices fails to support the media volume synchronization function, the processor may abstain from using the media volume synchronization function in the operation mode. In this case, the processor may display a popup window  920  for deactivating the media volume synchronization function to activate the operation mode in the activated state of the media volume synchronization function as shown in (c) of  FIG. 9 . Upon receipt of a user input  921  to deactivate the media volume synchronization function through the popup window  920 , the processor may deactivate the media volume synchronization function and activate the operation mode. 
     As another example, when all of the plurality of external devices support the media volume synchronization function, the processor may use the media volume synchronization function even in the operation mode. In this case, the processor may abstain from displaying the popup window  920  for deactivating the media volume synchronization function to activate the operation mode even in the activated state of the media volume synchronization function as shown in (c) of  FIG. 9 . The processor may simultaneously activate the operation mode and the media volume synchronization function. 
     As another example, even when all of the plurality of external devices support the media volume synchronization function, the processor may abstain from using the media volume synchronization function according to the settings of the electronic device  101  or the plurality of external devices. In this case, the processor may display the popup window  920  to activate the operation mode. 
       FIGS. 10A and 10B  are diagrams illustrating a method for setting an operation mode for transmitting audio data to multiple external devices on an electronic device, according to an embodiment of the present disclosure. 
     According to an embodiment of the present disclosure, as shown in (a) of  FIG. 10A , a processor  120  of the electronic device  101  may display a screen for bluetooth connection. While being in connection with only a first external device  1001 , the processor may receive a user input  1010  for connection with a second external device  1002 . For example, when the electronic device is connected with the first external device  1001  using a bluetooth profile (e.g., an A2DP) for transmission of audio data, the processor may display text (e.g., “connected for media audio”) to indicate that audio data can be transmitted to the first external device  1001 , as shown in (a) of  FIG. 10A . 
     As shown in (b) of  FIG. 10A , according to a user input  1010 , the processor may connect with the second external device  1002  and represent through the screen for bluetooth connection that the electronic device is being connected with the first external device  1001  and the second external device  1002 . For example, where the electronic device is connected with the second external device  1002  using a bluetooth profile (e.g., an A2DP) for transmission of audio data, the processor may display text (e.g., “connected for media audio”) to indicate that audio data can be transmitted to the second external device  1002 , as shown in (b) of  FIG. 10A . 
     Upon sensing connection with the first external device  1001  and the second external device  1002  while the operation mode is not activated, the processor may display a popup window  1020  for entry into an operation mode (e.g., a dual audio mode) configuration screen for transmitting audio data to the plurality of external devices. The popup window  1020  may be displayed only when the processor first senses connection with the plurality of external devices regardless of the bootup of the electronic device  101  or after the electronic device  101  boots up, or whenever it senses connection with the plurality of external devices. 
     For example, the processor may receive a user input  1021  for entry into the screen for setting the operation mode through the popup window  1020 . As another example, the processor, despite not displaying the popup window  1020 , may receive a user input for entry into the operation mode configuration screen and display the operation mode configuration screen according to the user input. 
     As another example, the processor may receive a user input  1022  for abstaining from activating the operation mode through the popup window  1020 . In this case, the processor may transmit audio data to one of the first external device  1001  or the second external device  1002 . For example, the processor may transmit audio data to the second external device  1002 , which is connected later, of the first external device  1001  or the second external device  1002 . 
     The processor may display a screen for setting the operation mode according to a user input  1020 , as shown in (c) of  FIG. 10A . The processor may receive a user input  1030  to activate the operation mode while the screen is being displayed. 
     For example, the processor may activate the operation mode according to the user input  1030  and represent that the operation mode is in the activated state through the screen for setting the operation mode as shown in (d) of  FIG. 10A . As the operation mode is activated, the processor may select a codec commonly supported by the first external device  1001  and the second external device  1002  to transmit audio data to the first external device  1001  and the second external device  1002 . 
     According to an embodiment of the present disclosure, a processor  120  of the electronic device  101  may display a screen for setting an operation mode (e.g., a dual audio mode) for transmitting audio data to multiple external devices, as shown in (a) of  FIG. 10B . For example, the processor may activate the operation mode through the screen even when the electronic device is connected with only one electronic device, e.g., the first external device  1001 . 
     The processor may display a screen for bluetooth connection in the activated state of the operation mode. As shown in (b) of  FIG. 10B , the processor may represent the state of being connected with only the first external device  1001  through the screen for bluetooth connection. For example, where the electronic device is connected with the first external device  1001  using a bluetooth profile (e.g., an A2DP) for transmission of audio data, the processor may display text (e.g., “connected for media audio”) to indicate that audio data can be transmitted to the first external device  1001 , as shown in (b) of  FIG. 10B . 
     For example, while being in connection with only the first external device  100 , the processor may receive a user input  1030  for connection with the second external device  1002 . 
     As shown in (c) of  FIG. 10B , according to a user input  1030 , the processor may connect with the second external device  1002  and represent through the screen for bluetooth connection that the electronic device is being connected with the first external device  1001  and the second external device  1002 . For example, where the electronic device is connected with the second external device  1002  using a bluetooth profile (e.g., an A2DP) for transmission of audio data, the processor may display text (e.g., “connected for media audio”) to indicate that audio data can be transmitted to the second external device  1002 , as shown in (c) of  FIG. 10B . 
     For example, as a connection with the second external device  1002  is made in the activated state of the operation mode, the processor may select a codec commonly supported by the first external device  1001  and the second external device  1002  to transmit audio data to the first external device  1001  and the second external device  1002 . 
     According to an embodiment of the present disclosure, the operation mode setting operation described above in connection with  FIGS. 10A and 10B  may also be performed by another electronic device (e.g., a smartwatch) wirelessly connected with the electronic device  101 . For example, the processor may perform the operation mode setting operation according to a control signal for setting the operation mode that is received from the other electronic device. 
       FIG. 11  is a flowchart illustrating a method for reducing the transmission speed of audio data transmitted to multiple external devices by an electronic device, according to an embodiment of the present disclosure. 
     In operation  1110 , a processor  120  of the electronic device  101  monitors retransmission rates of data transmitted to the first external device and the second external device through wireless channels. For example, the processor may monitor a first retransmission rate of audio data processed using a selected codec transmitted through a first wireless channel established with the first external device and a second retransmission rate of audio data processed using the selected codec transmitted through a second wireless channel established with the second external device. 
     In operation  1120 , the processor determines whether the first retransmission rate or the second retransmission rate is greater than or equal to a designated threshold. When the first retransmission rate or the second retransmission rate is greater than or equal to the designated threshold, the processor may determine that the first or second wireless channel is in a poor environment. 
     When the first retransmission rate and the second retransmission rate are less than the designated threshold, the process returns to operation  1110  to monitor retransmission rates of processed audio data transmitted through first and second wireless channels. 
     When the first retransmission rate or the second retransmission rate is greater than or equal to the designated threshold, the processor decreases a first bit rate for transmitting the processed audio data through the first wireless channel and a second bit rate for transmitting the processed audio data through the second wireless channel, in operation  1130 . For example, the processor may reduce the first bit rate and the second bit rate by increasing the compression rate of the selected codec so that the amount of data transmitted is decreased or changing to a codec with a higher compression rate among codecs commonly supported by the first external device and the second external device in processing the audio data. 
     For example, the processor may reduce both the first bit rate and the second bit rate, not only when both the first retransmission rate and the second retransmission rate are greater than or equal to the designated threshold, but also when either the first retransmission rate or the second retransmission rate are greater than or equal to the designated threshold. 
     For example, the processor may reduce the first bit rate and the second bit rate to the same level. Even where either the first retransmission rate or the second retransmission rate is not less than the designated threshold, the processor may reduce both the first bit rate and the second bit rate to the same level. 
     As another example, the processor may differentially reduce the first bit rate and the second bit rate based on the first retransmission rate and the second retransmission rate. For example, when only the first retransmission rate is greater than or equal to the designated threshold, the processor may reduce the first bit rate to a first bit rate value while reducing the second bit rate to a second bit rate value that is higher than the first bit rate value. The processor may differentially reduce the first bit rate and the second bit rate depending on the environment of the first wireless channel and the second wireless channel, such as, for example, the first retransmission rate and the second retransmission rate. 
     In operation  1140 , after reducing the first bit rate and the second bit rate, the processor monitors the retransmission rate of data transmitted to the first and second external devices through the wireless channels. For example, when the wireless channel environment is determined to be good by monitoring the retransmission rate of data transmitted to the first and second external devices, the processor may increase the first and second bit rates that have been reduced. 
       FIG. 12  is a flowchart illustrating a method for reducing the transmission speed of audio data transmitted to one of multiple external devices by an electronic device, according to an embodiment of the present disclosure. 
     In operation  1210 , a processor  120  of the electronic device  101  monitors the retransmission rate of data through a wireless channel. For example, the processor may monitor a first retransmission rate of audio data processed using a selected codec transmitted through a first wireless channel established with the first external device and a second retransmission rate of audio data processed using the selected codec transmitted through a second wireless channel established with the second external device. The processor may determine whether to reduce a first bit rate for transmitting the processed audio data through the first wireless channel or a second bit rate for transmitting the processed audio data through the second wireless channel according to the first retransmission rate or second retransmission rate monitored. 
     In operation  1220 , the processor determines whether the first retransmission rate is greater than or equal to a designated threshold. When the first retransmission rate is greater than or equal to the designated threshold, the processor may determine that the first wireless channel is in a poor environment. 
     When the first retransmission rate is less than the designated threshold, the process returns to operation  1210  to monitor retransmission rates of processed audio data. When the first retransmission rate is greater than or equal to the designated threshold, the processor reduces the first bit rate, in operation  1230 . For example, the processor may reduce the first bit rate by increasing the compression rate of the selected codec in processing audio data to be transmitted to the first external device. 
     For example, the processor may reduce the first bit rate based on a designated bit rate range in the selected codec. The processor may reduce the first bit rate within the designated bit rate range in the selected codec. 
     For example, the processor may reduce the first bit rate while fixing the second bit rate. As another example, the processor may increase the second bit rate by the degree to which the first bit rate has been reduced. Sine bluetooth communication is performed within a limited frequency band so that the amount of data transmitted is limited, the sum of the first bit rate and the second bit rate may be below a designated bit rate (about 500 kbps). Accordingly, the processor may increase the second bit rate as the first bit rate decreases. 
     In operation  1240 , the processor determines whether the second retransmission rate is greater than or equal to the designated threshold. When the second retransmission rate is greater than or equal to the designated threshold, the processor may determine that the second wireless channel is in a poor environment. 
     When the second retransmission rate is less than the designated threshold, the process returns to operation  1210  to monitor retransmission rates of processed audio data. When the second retransmission rate is greater than or equal to the designated threshold, the processor reduces the second bit rate, in operation  1250 . For example, the processor may reduce the second bit rate by increasing the compression rate of the selected codec in processing audio data to be transmitted to the second external device. 
     For example, the processor may reduce the second bit rate based on a designated bit rate range in the selected codec. The processor may reduce the second bit rate within the designated bit rate range in the selected codec. 
     For example, the processor may reduce only the second bit rate while fixing the first bit rate. As another example, the processor may increase the first bit rate by the degree to which the second bit rate has been reduced. 
     In operation  1260 , after reducing the first bit rate or the second bit rate, the processor may monitor the retransmission rate of data transmitted to the first and second external devices through the wireless channels. For example, when the first or second wireless channel environment is determined to be good by monitoring the retransmission rate of data transmitted to the first and second external devices, the processor may increase the first or second bit rate that has been reduced. 
       FIG. 13  is a flowchart illustrating a method for increasing the transmission speed of audio data transmitted to multiple external devices by an electronic device, according to an embodiment of the present disclosure. 
     In operation  1310 , a processor  120  of the electronic device  101  monitors a first retransmission rate of audio data processed using a selected codec transmitted through a first wireless channel established with the first external device and a second retransmission rate of audio data processed using the selected codec transmitted through a second wireless channel established with the second external device. 
     In operation  1320 , the processor determines whether the first retransmission rate and the second retransmission rate are less than a designated threshold. When the first retransmission rate and the second retransmission rate are less than the designated threshold, the processor may determine that the first and second wireless channels are in a good environment. 
     When the first retransmission rate and the second retransmission rate are not less than the designated threshold, the process returns to operation  1310  to monitor retransmission rates of processed audio data. When the first retransmission rate and the second retransmission rate are less than the designated threshold, the processor increases the first bit rate and the second bit rate, in operation  1330 . For example, the processor may increase the first and second bit rates within the designated bit rate range in the selected codec. As another example, the processor may increase the first bit rate and the second bit rate so that the sum of the increasing first bit rate and second bit rate are below a designated bit rate (about 500 kbps). 
     For example, the processor may increase the first bit rate and the second bit rate by decreasing the compression rate of the selected codec or changing to a codec with a lower compression rate among codecs commonly supported by the first external device and the second external device in processing the audio data. 
     For example, where only one of the first retransmission rate and the second retransmission rate is less than the designated threshold, the processor may abstain from increasing the first bit rate and the second bit rate. Bluetooth communication is performed within a limited frequency band. Thus, the retransmission rate remaining high in one channel of the frequency band may influence communication through the other channels. Hence, where only one of the first retransmission rate and the second retransmission rate is less than the designated threshold, the processor may abstain from increasing both the first bit rate and the second bit rate. 
     In operation  1340 , after increasing the first bit rate and the second bit rate, the processor monitors the retransmission rate of data transmitted to the first and second external devices through the wireless channels. For example, when the wireless channel environment is determined to have worsened by monitoring the retransmission rate of data transmitted to the first and second external devices, the processor may decrease the first and second bit rates that have been increased. 
       FIG. 14  is a flowchart illustrating a method for increasing the transmission speed of audio data transmitted to one of multiple external devices by an electronic device, according to an embodiment of the present disclosure. 
     In operation  1410 , a processor  120  of the electronic device  101  may monitor a first retransmission rate of audio data processed using a selected codec transmitted through a first wireless channel established with the first external device and a second retransmission rate of audio data processed using the selected codec transmitted through a second wireless channel established with the second external device. 
     In operation  1420 , the processor determines whether the first retransmission rate is less than a designated threshold. Where the first retransmission rate is less than the designated threshold, the processor may determine that the first wireless channel is in a good environment. 
     When the first retransmission rate is not less than the designated threshold, the process returns to operation  1410  to monitor retransmission rates of processed audio data. When the first retransmission rate is less than the designated threshold, the processor increases the first bit rate, in operation  1430 . For example, the processor may increase the first bit rate by reducing the compression rate of the selected codec or changing to a codec with a lower compression rate among codecs commonly supported by the first external device and the second external device in processing the audio data to be transmitted to the first external device. 
     For example, the processor may increase the first bit rate within the designated bit rate range in the selected codec. The processor may increase the first bit rate so that the sum of the increasing first bit rate and second bit rate are below a designated bit rate (about  500  kbps). 
     As another example, the processor may determine how much it is to increase the first bit rate further considering the second retransmission rate. Bluetooth communication is performed within a limited frequency band. Thus, the retransmission rate remaining high in one channel of the frequency band may influence communication through the other channels. Hence, the processor may take the second retransmission rate into account to increase the first bit rate. 
     In operation  1440 , the processor determines whether the second retransmission rate is less than a designated threshold. Where the second retransmission rate is less than the designated threshold, the processor may determine that the second wireless channel is in a good environment. 
     When the second retransmission rate is not less than the designated threshold, the process returns to operation  1410  to monitor retransmission rates of processed audio data. When the second retransmission rate is less than the designated threshold, the processor may increase the second bit rate, in operation  1450 . For example, the processor may increase the second bit rate by reducing the compression rate of the selected codec or changing to a codec with a lower compression rate among codecs commonly supported by the first external device and the second external device in processing the audio data to be transmitted to the second external device. 
     For example, the processor may increase the second bit rate within the designated bit rate range in the selected codec. The processor may increase the second bit rate so that the sum of the increasing second bit rate and first bit rate are below a designated bit rate (about  500  kbps). 
     As another example, the processor may determine how much it is to increase the second bit rate further considering the first retransmission rate. Bluetooth communication is performed within a limited frequency band. Thus, the retransmission rate remaining high in one channel of the frequency band may influence communication through the other channels. Hence, the processor may take the first retransmission rate into account to increase the second bit rate. 
     In operation  1460 , after increasing the first bit rate or the second bit rate, the processor monitors the retransmission rate of data transmitted to the first and second external devices through the wireless channels. For example, when the first or second wireless channel environment is determined to have worsened by monitoring the retransmission rate of data transmitted to the first and second external devices, the processor may decrease the first or second bit rate that has been increased. 
       FIG. 15  is a flowchart illustrating a method for establishing a wireless channel with an external device by an electronic device, according to an embodiment of the present disclosure. 
     In operation  1510 , the electronic device  101  discovers at least one stream end point that an external device  1501  supports. For example, when the external device  1501  supports a plurality of codecs, a plurality of stream end points may be provided. For example, when the external device  1501  supports an SBC codec and an aptX codec, two stream end points may be provided. 
     In operation  1520 , the electronic device  101  receives codec information about the at least one stream end point discovered and identifies the codec information about the at least one stream end point. For example, the electronic device  101  may identify the codec information, such as the type and supporting range of codec, about the at least one stream end point based on the received codec information. The electronic device  101  may send a request for the codec to the external device  1501  and receive the codec information. Even when there is no request from the electronic device  101 , the external device  1501  may send out the codec information. 
     In operation  1530 , the electronic device  101  transmits information about a codec to be used to transmit audio data to the external device  1501  based on the identified codec information. For example, when a plurality of codecs are supported by the external device  1501 , the electronic device  101  may select a codec to be used to transmit audio data to the external device  1501  based on designated priorities and transmit the information about the codec to the first external device  1501 . 
     As another example, operations  1510  to  1530  may be performed by the external device  1501 . For example, the external device  1501  may discover at least one stream end point that the electronic device  101  supports. The external device  1501  may receive codec information about the at least one stream end point discovered and identify the codec information about the at least one stream end point. The external device  1501  may transmit information about a codec to be used for transmission of audio data to the electronic device  101  based on the identified codec information, and the electronic device  101  may select a codec to be used to transmit audio data according to the received information. 
     In operation  1540 , the electronic device  101  establishes a wireless channel for transmission of audio data with the external device  1501 . 
     In operation  1550 , the electronic device  101  transmits audio data processed (e.g., encoded) using the selected codec to the external device  1501  through the established wireless channel. The external device  1501  may process (e.g., decode) the processed audio data received with the same codec as the selected codec and play the audio data. 
     As set forth above, in the operation of establishing the wireless channel with the external device  1501 , the electronic device  101  may identify the information about at least one codec the external device  1501  supports. 
       FIG. 16  is a flowchart illustrating a method for transmitting audio data to multiple external devices by an electronic device, according to an embodiment of the present disclosure. 
     In operation  1611 , the electronic device  101  establishes a first wireless channel with a first external device  1601 . For example, as shown in  FIG. 15 , the electronic device  101  may establish the first wireless channel with the first external device  1601 . 
     In operation  1612 , the electronic device  101  establishes a second wireless channel with a second external device  1602 . For example, as shown in  FIG. 15 , the electronic device  101  may establish the second wireless channel with the second external device  1602 . 
     In operation  1613 , the electronic device  101  activates an operation mode for transmitting audio data to the first and second external devices  1601  and  1602  according to a user input. For example, the operation mode may be activated after the electronic device  101  connects to each of the first external device  1601  and the second external device  1602 , as shown, or although not shown, the operation mode may be activated after the electronic device  101  connects with only the first external device  1601 . When the operation mode is activated after the electronic device connects with only the first external device  1601 , operation  1612  may be performed after operation  1613 . 
     In operation  1614 , the electronic device  101  selects a codec that the first and second external devices  1601  and  1602  support among a plurality of codecs stored in the electronic device  101 . For example, as the operation mode is activated, the electronic device  101  may select a codec that the first and second external devices  1601  and  1602  support. As another example, the electronic device  101  connects with only the first external device  1601 , and as the electronic device  101  connects with the second external device  1602  in the activated state of the operation mode, the electronic device  101  may select a codec that the first and second external devices  1601  and  1602  support. 
     In operation  1615 , the electronic device  101  processes audio data using the selected codec, which is commonly supported by the first and second external devices  1601  and  1602 . 
     In operation  1616 , the electronic device  101  transmits the processed audio data through the first wireless channel to the first external device  1601 . In operation  1617 , the electronic device  101  transmits the processed audio data through the second wireless channel to the second external device  1602 . 
     In operations  1618  and  1619 , the first and second external devices  1601  and  1602  process (e.g., decode) the processed audio data with the same codec as the selected codec and play the audio data. 
     In operation  1620 , the electronic device  101  monitors the environment of the first and second wireless channels. For example, the electronic device  101  may monitor the retransmission rate of the processed audio data transmitted through the first and second wireless channels. 
     In operations  1621  and  1622 , the electronic device  101  controls the transmission speed (e.g., bit rate) of the processed audio data according to the results of monitoring. For example, the electronic device  101  may control the transmission speed by controlling the bit rate for transmitting the processed audio data through the first and second wireless channels. 
     In operation  1623 , the electronic device  101  deactivates the operation mode according to a user input. 
     In operation  1624 , the electronic device  101  selects one of the first and second external devices  1601  and  1602  to transmit audio data as the operation mode is deactivated. For example, the electronic device  101  may select the second external device  1602  as the device to transmit audio data according to order of connection with the electronic device  101  between the first and second external devices  1601  and  1602 . 
     In operation  1625 , as the second external device  1602  is selected, transmission of audio data to the first external device  1601  pauses, and the first external device  1601  stops playing audio data. 
     In operation  1626 , the electronic device  101  changes codecs for processing (e.g., encoding) audio data based on information about codecs that the selected second external device  1602  supports. For example, where a first codec used to transmit audio data while the operation mode is active differs from a second codec to be used to transmit audio data to the second external device  1602 , the electronic device  101  may change codecs for processing audio data. According to an embodiment of the present disclosure, the second codec may be a codec commonly supported by the electronic device  101  and the second external device  1602 , and the second codec may be determined based on a priority designated by the electronic device  101  or the second external device  1602 . 
     When the first codec is the same as the second codec, no codec change for processing audio data may be performed. 
     According to an embodiment of the present disclosure, the electronic device  101  may change codecs for processing audio data using an interval when the playback of audio data pauses to prevent sound drops. 
     In operation  1627 , the electronic device  101  processes (e.g., encodes) audio data using the changed codec. In operation  1628 , the electronic device  101  transmits the audio data processed using the changed codec to the second external device  1602 . In operation  1629 , the second external device  1602  processes (e.g., decodes) the processed audio data with the same codec as the changed codec and play the audio data. 
     According to an embodiment of the present disclosure, an electronic device may comprise a housing, a display provided on the housing, a wireless communication circuit disposed in the housing and configured to support bluetooth-based wireless communication, a processor disposed in the housing and electrically connected with the user interface and the wireless communication circuit, and a memory disposed in the housing, electrically connected with the processor, and storing a plurality of codecs for processing audio data. The memory may store instructions executed to enable the processor to establish a first wireless channel with a first external device using the wireless communication circuit, establish a second wireless channel with a second external device using the wireless communication circuit, select a codec supported by the first external device and the second external device from among the plurality of codecs, process the audio data using the selected codec, and transmit the processed audio data to the first external device and the second external device through the first wireless channel and the second wireless channel using the wireless communication circuit. 
     The instructions may enable the processor to receive information about at least one codec supported by each of the first external device and the second external device from the first external device and the second external device. 
     The instructions may enable the processor to select the one codec supported by the first external device and the second external device from among the plurality of codecs based on the information. 
     The instructions may enable the processor to select the one codec from among the plurality of codecs supported by the first external device and the second external device based on priorities of the plurality of codecs when two or more of the plurality of codecs are supported by the first external device and the second external device. 
     The priorities of the plurality of codecs may be designated based on at least one of a compression rate, a degree of loss in sound quality due to compression, whether a bit rate for transmitting audio data is variable by controlling the compression rate, or a perceptual evaluation audio quality (PEAQ) value. 
     The selected codec may include a low complexity subband coding (SBC) codec. 
     The instructions may enable the processor to monitor a retransmission rate of the processed audio data through each of the first wireless channel and the second wireless channel and control at least one of a first bit rate for transmitting the processed audio data through the first wireless channel or a second bit rate for transmitting the processed audio data through the second wireless channel based on a result of the monitoring. 
     The instructions may enable the processor to decrease the first bit rate and the second bit rate when a first retransmission rate monitored of the processed audio data through the first wireless channel or a second retransmission rate of the processed audio data through the second wireless channel is not less than a designated threshold. 
     The instructions may enable the processor to decrease the first bit rate when a first retransmission rate monitored of the processed audio data through the first wireless channel is not less than a designated threshold. 
     The instructions may enable the processor to decrease the first bit rate based on a bit rate range designated in the selected codec. 
     The instructions may enable the processor to select one codec selected by the first external device and the second external device from among the plurality of codecs upon receiving a first user input for activating an operation mode for transmitting the audio data to the first external device and the second external device. 
     The instructions may enable the processor to select one of the first external device and the second external device upon receiving a second user input for deactivating the operation mode, transmit the audio data processed using one codec supported by the selected external device among the plurality of codecs to the selected external device, and restrict transmission of the processed audio data to one not selected between the first external device and the second external device. 
     The one codec supported by the selected external device may be a codec used to transmit the audio data to the selected external device before the operation mode is activated among the plurality of codecs. 
     The instructions may enable the processor to, when an operation mode for transmitting the audio data to the first external device and the second external device is activated, display, through the display, a graphical object for representing the activation of the operation mode. 
     According to an embodiment of the present disclosure, there may be provided a non-transitory computer-readable recording medium retaining a program executed on a computer, wherein the program may comprise executable commands that, when executed by a processor (e.g., the processor  120 ), enable the processor to establish a first wireless channel with a first external device, establish a second wireless channel with a second external device, select a codec supported by the first external device and the second external device from among a plurality of codecs for processing audio data, process the audio data using the selected codec, and transmit the processed audio data to the first external device and the second external device through the first wireless channel and the second wireless channel. 
     Selecting the codec supported by the first external device and the second external device from among the plurality of codecs may include selecting the codec supported by the first external device and the second external device from among the plurality of codecs based on information about at least one codec supported by each of the first external device and the second external device received from the first external device and the second external device. 
     Selecting the codec supported by the first external device and the second external device from among the plurality of codecs may include selecting the codec supported by the first external device and the second external device from among the plurality of codecs based on priorities of the plurality of codecs when two or more of the plurality of codecs are supported by the first external device and the second external device. 
     The program may comprise commands executed to enable the processor to monitor a retransmission rate of the processed audio data through the first wireless channel and the second wireless channel and control at least one of a first bit rate for transmitting the processed audio data through the first wireless channel or a second bit rate for transmitting the processed audio data through the second wireless channel based on a result of the monitoring. 
     Controlling the at least one of the first bit rate or the second bit rate based on the result of the monitoring may include decreasing the first bit rate and the second bit rate when a first retransmission rate monitored of the processed audio data through the first wireless channel or a second retransmission rate of the processed audio data through the second wireless channel is not less than a designated threshold. 
     According to an embodiment of the present disclosure, an electronic device may comprise a housing, a wireless communication circuit disposed in the housing and configured to support bluetooth-based wireless communication, a processor disposed in the housing and electrically connected with the wireless communication circuit, and a memory disposed in the housing, electrically connected with the processor, and storing a plurality of codecs for processing audio data. The memory may store instructions executed to enable the processor to transmit the audio data processed using a codec selected from among the plurality of codecs through a first wireless channel and a second wireless channel to a first external device and a second external device, monitor a retransmission rate of the processed audio data through each of the first wireless channel and the second wireless channel, and control a bit rate of the audio data transmitted through each of the first wireless channel and the second wireless channel based on a result of the monitoring. 
     Each of the aforementioned components of the electronic device may include one or more parts, and a name of the part may vary with a type of the electronic device. The electronic device in accordance with various embodiments of the present disclosure may include at least one of the aforementioned components, omit some of them, or include other additional component(s). Some of the components may be combined into an entity, but the entity may perform the same functions as the components may do. 
     As used herein, the term “module” includes a unit configured in hardware, software, or firmware and may interchangeably be used with other terms, such as, for example, “logic”, “logic block”, “part”, or “circuit.” A module may be a single integral part or a minimum unit or part of performing one or more functions. A module may be implemented mechanically or electronically and may include, for example, an application-specific integrated circuit (ASIC) chip, field-programmable gate arrays (FPGAs), or programmable logic device, that has been known or to be developed in the future as performing some operations. 
     According to an embodiment of the present disclosure, at least a part of the device (e.g., modules or their functions) or method (e.g., operations) may be implemented as instructions stored in a computer-readable storage medium (e.g., the memory  130  of  FIG. 1 ), for example, in the form of a program module. The instructions, when executed by a processor (e.g., the processor  120  of  FIG. 1 ), may enable the processor to carry out a corresponding function. 
     The computer-readable medium may include, for example, a hard disk, a floppy disc, a magnetic medium (e.g., magnetic tape), an optical recording medium (e.g., compact disc-read only memory (CD-ROM), digital versatile disc (DVD), magnetic-optical medium (e.g., floptical disk), or an embedded memory. The instruction may include a code created by a compiler or a code executable by an interpreter. Modules or programming modules in accordance with various embodiments of the present disclosure may include at least one or more of the aforementioned components, omit some of them, or further include other additional components. Operations performed by modules, programming modules or other components in accordance with various embodiments of the present disclosure may be carried out sequentially, in parallel, repeatedly or heuristically, or at least some operations may be executed in a different order or omitted or other operations may be added. 
     According to an embodiment of the present disclosure, there may be provided a non-transitory computer-readable recording medium retaining a program executed on a computer, wherein the program may comprise executable commands that, when executed by a processor, enable the processor to establish a first wireless channel with a first external device, establish a second wireless channel with a second external device, select a codec supported by the first external device and the second external device from among a plurality of codecs for processing audio data, process the audio data using the selected codec, and transmit the processed audio data to the first external device and the second external device through the first wireless channel and the second wireless channel. 
     As is apparent from the foregoing description, according to various embodiments of the present disclosure, an electronic device may select a codec supported by multiple external devices connected via short-range wireless communication and transmit audio data processed using the selected codec to the multiple external devices. 
     According to various embodiments of the present disclosure, an electronic device may control the transmission speed of audio data transmitted to multiple external devices by monitoring a wireless channel environment established between the electronic device and each of the external devices. 
     While the disclosure has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims.