Patent Publication Number: US-2023137317-A1

Title: Audio playback device capable of cooperating with plural audio generating devices without conducting bluetooth pairing procedure and related bluetooth audio system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Application Ser. No. 63/273,156, filed on Oct. 29, 2021; the entirety of which is incorporated herein by reference for all purposes. 
    
    
     BACKGROUND 
     The disclosure generally relates to Bluetooth technologies and, more particularly, to an audio playback device capable of cooperating with plural audio generating devices without conducting Bluetooth pairing procedure with the audio generating devices, and related Bluetooth audio systems. 
     A speaker and plural separate microphone devices can form a Bluetooth audio system (e.g., a Bluetooth conference system, a Bluetooth video conference system, a Bluetooth karaoke system, a Bluetooth smart speaker system, etc.) by realizing the wireless transmission of audio signals between the speaker and the microphone devices with Bluetooth communication technology. However, there are many limitations in the use of traditional Bluetooth audio systems. For example, before using the traditional Bluetooth audio system, the user has to first perform a Bluetooth pairing procedure on the speaker and all the microphone devices one by one, so that the microphone devices can transmit audio signals to the speaker by using the Bluetooth transmission mechanism. 
     As is well known in the art, the user usually has to spend a lot of time to complete the manual Bluetooth pairing procedure between different devices. Additionally, the greater the number of microphone devices in the Bluetooth audio system, the longer the Bluetooth pairing procedure will take. Therefore, if the audio transmission mechanism adopted by the Bluetooth audio system cannot be changed, the operational convenience and application prospect of the Bluetooth audio system will inevitably be limited. 
     SUMMARY 
     An example embodiment of a Bluetooth audio system is disclosed, comprising: an audio playback device comprising: an audio processing circuit arranged to operably control an audio playback circuit; a control circuit coupled with the audio processing circuit and arranged to operably generate one or more Bluetooth audio transmission parameters corresponding to an audio broadcasting timing indicator; and a Bluetooth communication circuit coupled with the control circuit and arranged to operably transmit the one or more Bluetooth audio transmission parameters; a first audio generating device comprising: a first sound capturing circuit arranged to operably capture surrounding sounds to generate a corresponding first audio signal; a first audio conversion circuit coupled with the first sound capturing circuit and arranged to operably generate corresponding one or more first audio packets according to the first audio signal; and a first Bluetooth transmission circuit coupled with the first audio conversion circuit and arranged to operably receive the one or more Bluetooth audio transmission parameters when the first audio generating device without conducting Bluetooth pairing with the audio playback device, and arranged to operably broadcast the one or more first audio packets through a BIS logical transport; and a second audio generating device comprising: a second sound capturing circuit arranged to operably capture surrounding sounds to generate a corresponding second audio signal; a second audio conversion circuit coupled with the second sound capturing circuit and arranged to operably generate corresponding one or more second audio packets according to the second audio signal; and a second Bluetooth transmission circuit coupled with the second audio conversion circuit and arranged to operably receive the one or more Bluetooth audio transmission parameters when the second audio generating device without conducting Bluetooth pairing with the audio playback device, and arranged to operably broadcast the one or more second audio packets through a BIS logical transport; wherein the Bluetooth communication circuit is further arranged to operably receive the one or more first audio packets broadcasted by the first audio generating device, and to operably receive the one or more second audio packets broadcasted by the second audio generating device; wherein the audio processing circuit is further arranged to operably generate a corresponding sound signal according to contents of the one or more first audio packets and the one or more second audio packets, and to operably control the audio playback circuit to playback the sound signal. 
     Another example embodiment of an audio playback device of a Bluetooth audio system is disclosed. The Bluetooth audio system comprising a first audio generating device and a second audio generating device. The audio playback device comprises: an audio processing circuit arranged to operably control an audio playback circuit; a control circuit coupled with the audio processing circuit and arranged to operably generate one or more Bluetooth audio transmission parameters corresponding to an audio broadcasting timing indicator; and a Bluetooth communication circuit coupled with the control circuit and arranged to operably transmit the one or more Bluetooth audio transmission parameters; wherein the first audio generating device captures surrounding sounds to generate a corresponding first audio signal, generates corresponding one or more first audio packets according to the first audio signal, and receives the one or more Bluetooth audio transmission parameters when the first audio generating device without conducting Bluetooth pairing with the audio playback device, and broadcasts the one or more first audio packets through a BIS logical transport; wherein the second audio generating device captures surrounding sounds to generate a corresponding second audio signal, generates corresponding one or more second audio packets according to the second audio signal, and receives the one or more Bluetooth audio transmission parameters when the second audio generating device without conducting Bluetooth pairing with the audio playback device, and broadcasts the one or more second audio packets through a BIS logical transport; wherein the Bluetooth communication circuit is further arranged to operably receive the one or more first audio packets broadcasted by the first audio generating device, and to operably receive the one or more second audio packets broadcasted by the second audio generating device; wherein the audio processing circuit is further arranged to operably generate a corresponding sound signal according to contents of the one or more first audio packets and the one or more second audio packets, and to operably control the audio playback circuit to playback the sound signal. 
     Both the foregoing general description and the following detailed description are examples and explanatory only, and are not restrictive of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a simplified functional block diagram of a Bluetooth audio system according to one embodiment of the present disclosure. 
         FIG.  2    shows a simplified flowchart of a method for generating and playbacking Bluetooth audio signals according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference is made in detail to embodiments of the invention, which are illustrated in the accompanying drawings. The same reference numbers may be used throughout the drawings to refer to the same or like parts, components, or operations. 
       FIG.  1    shows a simplified functional block diagram of a Bluetooth audio system  100  according to one embodiment of the present disclosure. The Bluetooth audio system  100  comprises an audio playback device  110  and a plurality of audio generating devices. For the convenience of description, four exemplary audio generating devices are shown in the embodiment if  FIG.  1   , which respectively are a first audio generating device  120 , a second audio generating device  130 , a third audio generating device  140 , and a fourth audio generating device  150 . 
     The first audio generating device  120 , the second audio generating device  130 , the third audio generating device  140 , and the fourth audio generating device  150  are respectively utilized to capture surrounding sounds to generate corresponding audio packets, and may adopt Bluetooth LE Audio technology (hereinafter referred to as BLE Audio technology) specified by the Bluetooth Core Specification Version 5.2 or newer versions to broadcast the generated audio packets. 
     The audio playback device  110  supports the BLE technology specified by the Bluetooth Core Specification Version 5.2 or newer versions, and may receive the audio packets broadcasted by the first audio generating device  120 , the second audio generating device  130 , the third audio generating device  140 , and the fourth audio generating device  150 . In addition, the audio playback device  110  may generate and playback corresponding sounds based on the received audio packets. 
     As shown in  FIG.  1     , the audio playback device  110  comprises a Bluetooth communication circuit  111 , an audio processing circuit  113 , an audio playback circuit  115 , and a control circuit  117 . The first audio generating device  120  comprises a first Bluetooth transmission circuit  121 , a first sound capturing circuit  123 , and a first audio conversion circuit  125 . The second audio generating device  130  comprises a second Bluetooth transmission circuit  131 , a second sound capturing circuit  133 , and a second audio conversion circuit  135 . 
     In the audio playback device  110 , the Bluetooth communication circuit  111  is arranged to operably receive and transmit various Bluetooth packets. The audio processing circuit  113  is coupled with the Bluetooth communication circuit  111  and the audio playback circuit  115 , and arranged to operably generate audio contents to be playbacked by the audio playback circuit  115 . The control circuit  117  is coupled with the Bluetooth communication circuit  111 , the audio processing circuit  113 , and the audio playback circuit  115 , and is arranged to operably control the operations of the Bluetooth communication circuit  111 , the audio processing circuit  113 , and the audio playback circuit  115 . 
     In practice, the Bluetooth communication circuit  111  may be realized with appropriate Bluetooth transmission circuits supporting the Bluetooth communication protocol of the Bluetooth Core Specification Version 5.2 or a newer version. The audio processing circuit  113  may be realized with digital computing circuits, microprocessors, Application Specific Integrated Circuits (ASICs), or digital-to-analog converters (DACs) capable of conducting various encoding/decoding processing and/or data format conversion on the audio data. The audio playback circuit  115  may be realized with various appropriate circuits capable of receiving and playbacking the audio data, such as various mono speakers or multi-channel speakers. The control circuit  117  may be realized with various packet processing circuits, digital computing circuits, microprocessors, or ASICs having appropriate computing ability and capable of parsing and generating Bluetooth packets. 
     In some embodiments, the aforementioned Bluetooth communication circuit  111  may be realized with appropriate Bluetooth transmission circuits that also support the Bluetooth communication protocol of earlier Bluetooth versions (e.g., Bluetooth 2.0, Bluetooth 3.0, Bluetooth 4.0, Bluetooth 4.2, or the like). In this situation, the aforementioned control circuit  117  should be designed to be able to parse and generate Bluetooth packets defined by the Bluetooth communication protocol of earlier Bluetooth versions. 
     Different functional blocks of the aforementioned audio playback device  110  may be realized with separate circuits or may be integrated into a single Bluetooth controller IC or a single device. In some embodiments, for example, the aforementioned audio processing circuit  113  may be integrated into the aforementioned control circuit  117 . In other words, the audio processing circuit  113  and the control circuit  117  may be realized with separate circuits or may be realized with a same circuit. In addition, if necessary, the Bluetooth communication circuit  111  may be coupled with additional antenna devices (not shown in the figures). 
     In practical applications, all functional blocks of the audio playback device  110  may be integrated together to be various appropriate devices or systems that support the Bluetooth communication protocol of the Bluetooth Core Specification Version 5.2 or a newer version, and capable of receiving audio data broadcasted by other devices using the BLE Audio technology, such as a Bluetooth speaker, a Bluetooth smart speaker, an audio playback device, a desktop computer, a notebook computer, a tablet computer, a mobile communication device (e.g., a smart phone), a wearable device, or the like. 
     In the first audio generating device  120 , the first Bluetooth transmission circuit  121  is arranged to operably receive and parse various Bluetooth packets, and to operably generate and transmit various Bluetooth packets. The first sound capturing circuit  123  is arranged to operably capture surrounding sounds to generate corresponding audio signals. The first audio conversion circuit  125  is coupled with the first Bluetooth transmission circuit  121  and the first sound capturing circuit  123 , and arranged to operably process the audio signals generated by the first sound capturing circuit  123  (e.g., encoding the audio signals and/or conducting format conversion) to generate corresponding audio packets. In addition, the first audio conversion circuit  125  is further arranged to operably utilize the first Bluetooth transmission circuit  121  to broadcast the generated audio packets. 
     In the second audio generating device  130 , the second Bluetooth transmission circuit  131  is arranged to operably receive and parse various Bluetooth packets, and to operably generate and transmit various Bluetooth packets. The second sound capturing circuit  133  is arranged to operably capture surrounding sounds to generate corresponding audio signals. The second audio conversion circuit  135  is coupled with the second Bluetooth transmission circuit  131  and the second sound capturing circuit  133 , and arranged to operably process the audio signals generated by the second sound capturing circuit  133  (e.g., encoding the audio signals and/or conducting format conversion) to generate corresponding audio packets. In addition, the second audio conversion circuit  135  is further arranged to operably utilize the second Bluetooth transmission circuit  131  to broadcast the generated audio packets. 
     In practice, each of the aforementioned first Bluetooth transmission circuit  121  and second Bluetooth transmission circuit  131  may be realized with appropriate Bluetooth transmission circuits supporting the Bluetooth communication protocol of the Bluetooth Core Specification Version 5.2 or a newer version, and capable of parsing and generating Bluetooth packets. Each of the aforementioned first sound capturing circuit  123  and the second sound capturing circuit  133  may be realized with various appropriate circuits capable of capturing and converting surrounding sounds into corresponding audio signals, such as various types of microphones. Each of the aforementioned first audio conversion circuit  125  and the second audio conversion circuit  135  may be realized with a digital computing circuit, a microprocessor, an Application Specific Integrated Circuit (ASIC), or a digital-to-analog converter (DAC) capable of conducting various encoding processing and/or data format conversion on audio signals. 
     In some embodiments, each of the aforementioned first Bluetooth transmission circuit  121  and second Bluetooth transmission circuit  131  may be realized with appropriate Bluetooth transmission circuits that also support the Bluetooth communication protocol of earlier Bluetooth versions (e.g., Bluetooth 2.0, Bluetooth 3.0, Bluetooth 4.0, Bluetooth 4.2, or the like). In this situation, each of the first Bluetooth transmission circuit  121  and the second Bluetooth transmission circuit  131  should be designed to be able to parse and generate Bluetooth packets defined by the Bluetooth communication protocol of earlier Bluetooth versions. 
     Furthermore, different functional blocks of the aforementioned first Bluetooth transmission circuit  121  may be realized with separate circuits or may be integrated into a single Bluetooth controller IC or a single device (e.g., a Bluetooth earphone, a Bluetooth speaker, a desktop computer, a notebook computer, a tablet computer, a mobile communication device, a wearable Bluetooth device, etc.). In addition, if necessary, the first Bluetooth transmission circuit  121  may be coupled with additional antenna devices (not shown in the figures). Similarly, different functional blocks of the aforementioned second Bluetooth transmission circuit  131  may be realized with separate circuits or may be integrated into a single Bluetooth controller IC or a single device (e.g., a Bluetooth earphone, a Bluetooth speaker, a desktop computer, a notebook computer, a tablet computer, a mobile communication device, a wearable Bluetooth device, etc.). In addition, if necessary, the second Bluetooth transmission circuit  131  may be coupled with additional antenna devices (not shown in the figures). 
     In some embodiments, the aforementioned first audio conversion circuit  125  and second audio conversion circuit  135  may be respectively integrated into the aforementioned first Bluetooth transmission circuit  121  and second Bluetooth transmission circuit  131 . 
     In other words, the aforementioned first audio conversion circuit  125  and first Bluetooth transmission circuit  121  may be realized with separate circuits or may be realized with a same circuit. Similarly, the aforementioned second audio conversion circuit  135  and second Bluetooth transmission circuit  131  may be realized with separate circuits or may be realized with a same circuit. 
     The main circuit structure and implementation of other audio generating devices in the Bluetooth audio system  100  (e.g., the third audio generating device  140  and the fourth audio generating device  150 ) are similar to the aforementioned first audio generating device  120  or second audio generating device  130 , but different additional circuit components may be configured in different audio generating devices, and the circuit structure of all audio generating devices are not limited to be exactly identical. 
     It can be appreciated from the foregoing descriptions that the structure of the Bluetooth audio system  100  can be utilized to implement various audio systems that support the Bluetooth communication protocol of the Bluetooth core specification version 5.2 or a newer version, and capable of playbacking sounds captured by different audio generating devices, such as a multi-user Bluetooth conference system, a multi-user Bluetooth video conference system, a multi-user Bluetooth karaoke system, a multi-person teaching system, a Bluetooth smart speaker system, a multi-user real-time voice communication system, a vehicular audio system, or the like. 
     As described previously, there are many limitations in the use of traditional Bluetooth audio systems. For example, before using the traditional Bluetooth audio system, the user has to first perform a Bluetooth pairing procedure on the speaker and all the microphone devices one by one, so that the microphone devices can transmit audio signals to the speaker by using the Bluetooth transmission mechanism. As one can imagine, it will take a lot of time for the user to complete the manual Bluetooth pairing procedure between all the microphone devices and the speaker. Furthermore, the greater the number of microphone devices in the Bluetooth audio system, the more time the user will spend in the Bluetooth pairing procedure. 
     In order to solve the aforementioned shortcomings in the use of the traditional Bluetooth audio system, the disclosed Bluetooth audio system  100  will adopt a different approach to realize the audio transmission mechanism between individual audio generating device and the audio playback device  110 . 
     The operations of the Bluetooth audio system  100  will be further described below by reference to  FIG.  2   .  FIG.  2    shows a simplified flowchart of a method for generating and playbacking Bluetooth audio signals according to another embodiment of the present disclosure. 
     In the flowchart of  FIG.  2   , operations within a column under the name of a specific device are operations to be performed by the specific device. For example, operations within a column under the label “audio playback device” are operations to be performed by the audio playback device  110 ; operations within a column under the label “first audio generating device” are operations to be performed by the first audio generating device  120 ; operations within a column under the label “second audio generating device” are operations to be performed by the second audio generating device  130 . 
     A user may utilize the audio playback device  110  to playback the sounds captured by some audio generating devices in the Bluetooth audio system  100 , so as to utilize the Bluetooth audio system  100  to realize various specific applications, such as a multi-user Bluetooth conference system, a multi-user Bluetooth video conference system, a multi-user Bluetooth karaoke system, a multi-person teaching system, a Bluetooth smart speaker system, a multi-user real-time voice communication system, a vehicular audio system, or the like. For ease of understanding, the method of  FIG.  2    will be elaborated below by taking a scenario where the audio playback device  110  is utilized to playback the sounds captured by the first audio generating device  120  and the second audio generating device  130  as an example. 
     When the user wants to use the audio playback device  110  to playback the sounds captured by the first audio generating device  120  and the second audio generating device  130  in real time, the first audio generating device  120  and the second audio generating device  130  may perform the operation  202  of  FIG.  2    according to a specific manipulation conducted by the user (e.g., pressing a power-on switch, pressing a specific function key, issuing a specific voice command, or issuing a specific command in various suitable ways). 
     In the operation  202 , the first Bluetooth transmission circuit  121  of the first audio generating device  120  and the second Bluetooth transmission circuit  131  of the second audio generating device  130  may enter a predetermined receiving mode. 
     The aforementioned predetermined receiving mode refers to various operation modes capable of receiving various Bluetooth advertising packets, various Broadcast Isochronous Stream (BIS) protocol data units (PDUs) (hereinafter referred to as BIS PDUs), and/or various Broadcast Isochronous Group (BIG) protocol data units (hereinafter referred to as BIG PDUs). 
     For example, the aforementioned predetermined receiving mode may be a LE Extended Passive Scan mode, a LE Extended Active Scan mode, a LE Extended Initiator mode, or a Periodic Scanning mode capable of receiving various Bluetooth advertising packets. 
     For another example, the aforementioned predetermined receiving mode may be an operation mode capable of receiving various PDUs through a Broadcast Isochronous Stream (BIS) logical transport (hereinafter referred to as BIS logical transport) and/or receiving various PDUs through a Broadcast Isochronous Group logical transport (hereinafter referred to as BIG logical transport), such as a Periodic Synchronization mode, a BIG Synchronization mode, or the like. Alternatively, the aforementioned predetermined receiving mode may be a combination of the aforementioned various operation modes. 
     On the other hand, the audio playback device  110  may enter a predetermined transmitting mode according to a specific manipulation of the user (e.g., pressing a specific button, issuing a specific voice command, or issuing a specific command in various suitable ways). The aforementioned predetermined transmitting mode refers to various operation modes capable of transmitting various Bluetooth advertising packets, various BIS PDUs, and/or various BIG PDUs. 
     For example, the aforementioned predetermined transmitting mode may be an Advertising mode, a Scannable mode, a Connectable mode, a Non-connectable mode, a Non-Scannable mode, a Periodic Advertising mode, a LE Extended Advertising mode, or a LE Periodic Advertising mode. For another example, the aforementioned predetermined transmitting mode may be a Broadcast Isochronous Broadcasting mode or a Broadcast Isochronous Synchronization mode capable of transmitting various BIS PDUs through the BIS logical transport and/or transmitting various BIG PDUs through the BIG logical transport. Alternatively, the aforementioned predetermined transmitting mode may be a combination of the aforementioned various operation modes. 
     In the operation  204 , the control circuit  117  may generate an audio broadcasting timing indicator corresponding to respective audio generating devices according to an internal clock CLK_INT of the audio playback device  110  and a quantity of audio generating devices to be cooperated with the audio playback device  110 . In operations, the control circuit  117  may divide each reception period of the Bluetooth communication circuit  111  into a corresponding quantity of time segments according to the quantity of audio generating devices to be cooperated with the audio playback device  110 , and then generate an audio broadcasting timing indicator that can be used to indicate the corresponding timing relationship between individual audio generating device and individual time segment. 
     In practice, the quantity of audio generating devices to be cooperated with the audio playback device  110  may be pre-recorded in a non-volatile memory or firmware inside the audio playback device  110  by the manufacturer or the vender of the audio playback device  110 . Alternatively, the quantity of audio generating devices to be cooperated with the audio playback device  110  may be inputted to the audio playback device  110  by the user through a suitable input interface (not shown in the figures) before using the audio playback device  110 , so that the control circuit  117  can obtain the quantity of audio generating devices to be cooperated with the audio playback device  110 . 
     In this embodiment, for example, the audio generating device to be cooperated with the audio playback device  110  are the first audio generating device  120  and the second audio generating device  130 . Accordingly, the control circuit  117  may divide each reception period of the Bluetooth communication circuit  111  into an even number of time segments, and assign these time segments to the first audio generating device  120  and the second audio generating device  130  respectively. Then, the control circuit  117  may express the timing relationship between the first audio generating device  120  and the second audio generating device  130  and respective time segments in various suitable data formats as an audio broadcasting timing indicator, so that the audio broadcasting timing indicator can be utilized to indicate which time segments correspond to the first audio generating device  120  and which time segments correspond to the second audio generating device  130 . In practice, the control circuit  117  may use a specific count value corresponding to a specific edge of the internal clock CLK_INT to indicate the start time point of a certain time segment, so that different time segments correspond to different count values respectively. 
     For example, the control circuit  117  may divide each reception period of the Bluetooth communication circuit  111  into four time segments, six time segments, eight time segments, ten time segments, or other even number of time segments. The control circuit  117  may assign odd-numbered time segments among the time segments to the first audio generating device  120 , and assign even-numbered time segments among the time segments to the second audio generating device  130 . The control circuit  117  may express the corresponding relationship between the first audio generating device  120  and the odd-numbered time segments (e.g., the mapping relationship between the first audio generating device  120  and a certain set of count values) and the corresponding relationship between the first audio generating device  120  and the even-numbered time segments (e.g., the mapping relationship between the first audio generating device  120  and another set of count values) in various suitable data formats to be an audio broadcasting timing indicator. 
     If the quantity of audio generating devices to be cooperated with the audio playback device  110  is four, then the control circuit  117  may divide each reception period of the Bluetooth communication circuit  111  into N time segments, and assign the N time segments to the four audio generating devices, wherein N is 4 or a multiple of 4. Then, the control circuit  117  may express the corresponding relationship between the four audio generating devices and respective time segments (e.g., the mapping relationship between individual audio generating device and related count values) in various suitable data formats to be an audio broadcasting timing indicator. As a result, the audio broadcasting timing indicator can be used to indicate the corresponding relationship between respective time segments and respective audio generating devices. 
     From another aspect, the aforementioned audio broadcasting timing indicator not only can be used to indicate which time segments correspond to which audio generation device, but also can be used to indicate the timing relationship among the operations of different audio generating devices (or the operating order of different audio generating devices). 
     In the operation  206 , the control circuit  117  may generate one or more Bluetooth audio transmission parameters corresponding to the aforementioned audio broadcasting timing indicator. For example, the control circuit  117  may utilize various appropriate data format to represent a predetermined indication data, a BIS interval calculated based on the quantity of audio generating devices to be cooperated with the audio playback device  110 , and the broadcasting timing corresponding to respective audio generating devices (e.g., the corresponding relationship between the identification data of respective audio generating devices and specific count values), so as to generate one or more Bluetooth audio transmission parameters corresponding to the aforementioned audio broadcasting timing indicator. 
     The aforementioned predetermined indication data may be a hardware identification data corresponding to the audio playback device  110 , a manufacturer identification data corresponding to the manufacturer of the audio playback device  110 , an operating mode indication data corresponding to a specific operating mode, and/or a function identification data corresponding to a specific function supported by the audio playback device  110 . 
     In some embodiments, the control circuit  117  may further allocate corresponding bandwidths for different audio generating devices respectively, and incorporate the bandwidths allocated to respective audio generating devices into the aforementioned one or more Bluetooth audio transmission parameters. 
     It can be appreciated from the descriptions of the operation  204  and the operation  206 , the broadcasting timing of respective audio generating devices to be cooperated with the audio playback device  110 , and the broadcast sequence among different audio generating devices are determined by the audio playback device  110  rather than by the individual audio generating devices. 
     In the operation  208 , the control circuit  117  may insert the aforementioned one or more Bluetooth audio transmission parameters into one or more predetermined data items. In operations, the control circuit  117  may insert the aforementioned one or more Bluetooth audio transmission parameters into a single or multiple specific fields of a single predetermined data item, or may separately insert the one or more Bluetooth audio transmission parameters into the specific fields of multiple predetermined data items. 
     For example, in some embodiments where the aforementioned predetermined data items are various Bluetooth advertising packets, the control circuit  117  may insert the aforementioned one or more Bluetooth audio transmission parameters into a single or multiple specific fields of a single Bluetooth advertising packet. Alternatively, the control circuit  117  may insert the aforementioned one or more Bluetooth audio transmission parameters into specific fields of multiple Bluetooth advertising packets. 
     For another example, in some embodiments where the aforementioned predetermined data items are various BIS PDUs or BIG PDUs, the control circuit  117  may insert the aforementioned one or more Bluetooth audio transmission parameters into a single or multiple specific fields of a single BIS PDU or a single or multiple specific fields of a single BIG PDU, or may alternatively insert the aforementioned one or more Bluetooth audio transmission parameters into specific fields of multiple BIS PDUs or multiple BIG PDUs. In practice, the aforementioned specific fields may be Event Counter fields, Sub-Event Counter fields, Payload Counter fields, or the like in the BIS PDUs or the BIG PDUs. 
     In the operation  210 , the control circuit  117  may transmit the aforementioned one or more predetermined data items through the Bluetooth communication circuit  111  under the predetermined transmitting mode, so that the first audio generating device  120 , the second audio generating device  130 , and other Bluetooth devices (e.g., the aforementioned third audio generating device  140  and fourth audio generating device  150 ) within the Bluetooth signal transmission range of the audio playback device  110  can receive the aforementioned one or more predetermined data items. 
     For example, in some embodiments where the aforementioned predetermined transmitting mode is the Scannable mode, the Connectable mode, the Non-connectable mode, or the Non-Scannable mode, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be one or more auxiliary advertising indication (AUX_ADV_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more extended advertising indication (ADV_EXT_IND) packets and one or more auxiliary advertising indication (AUX_ADV_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more advertising decision indication (ADV_DECISION_IND) packets, and one or more auxiliary advertising indication (AUX_ADV_IND) packets. 
     In this situation, if the aforementioned predetermined receiving mode is the LE Extended Passive Scan mode, the LE Extended Active Scan mode, or the LE Extended Initiator mode, then the first Bluetooth transmission circuit  121  and the second Bluetooth transmission circuit  131  may perform the operation  212  to receive the one or more predetermined data items transmitted from the audio playback device  110 . 
     For another example, in some embodiments where the aforementioned predetermined transmitting mode is the Non-connectable mode or the Non-Scannable mode, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be one or more auxiliary chain indication (AUX_CHAIN_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more extended advertising indication (ADV_EXT_IND) packets, one or more auxiliary advertising indication (AUX_ADV_IND) packets, and one or more auxiliary chain indication (AUX_CHAIN_IND) packets. 
     In this situation, if the aforementioned predetermined receiving mode is the LE Extended Passive Scan mode, then the first Bluetooth transmission circuit  121  and the second Bluetooth transmission circuit  131  may perform the operation  212  to receive the one or more predetermined data items transmitted from the audio playback device  110 . 
     For yet another example, in some embodiments where the aforementioned predetermined transmitting mode is the Scannable mode, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be one or more auxiliary scan response (AUX_SCAN_RSP) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more extended advertising indication (ADV_EXT_IND) packets, one or more auxiliary advertising indication (AUX_ADV_IND) packets, and one or more auxiliary scan response (AUX_SCAN_RSP) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more auxiliary scan response (AUX_SCAN_RSP) packets and one or more auxiliary chain indication (AUX_CHAIN_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more extended advertising indication (ADV_EXT_IND) packets, one or more auxiliary advertising indication (AUX_ADV_IND) packets, one or more auxiliary scan response (AUX_SCAN_RSP) packets, and one or more auxiliary chain indication (AUX_CHAIN_IND) packets. 
     In this situation, if the aforementioned predetermined receiving mode is the LE Extended Active Scan mode, then the first Bluetooth transmission circuit  121  and the second Bluetooth transmission circuit  131  may perform the operation  212  to receive the one or more predetermined data items transmitted from the audio playback device  110 . 
     For yet another example, in some embodiments where the aforementioned predetermined transmitting mode is the Non-connectable mode, the Non-Scannable mode, the Periodic Advertising mode, the LE Extended Advertising mode, or the LE Periodic Advertising mode, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be one or more auxiliary synchronous indication (AUX_SYNC_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more extended advertising indication (ADV_EXT_IND) packets, one or more auxiliary advertising indication (AUX_ADV_IND) packets, and one or more auxiliary synchronous indication (AUX_SYNC_IND) packets. 
     In this situation, if the aforementioned predetermined receiving mode is the Periodic Scanning mode, then the first Bluetooth transmission circuit  121  and the second Bluetooth transmission circuit  131  may perform the operation  212  to receive the one or more predetermined data items transmitted from the audio playback device  110 . 
     For yet another example, in some embodiments where the aforementioned predetermined transmitting mode is an advertising mode specified by the Bluetooth communication protocol of the Bluetooth Version 4.0, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be one or more advertising indication (ADV_IND) packets, one or more non-connectable advertising indication (ADV_NONCONN_IND) packets, or one or more discoverable advertisement indication (ADV_DISCOVER_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more advertising indication (ADV_IND) packets and one or more non-connectable advertising indication (ADV_NONCONN_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by one or more advertising indication (ADV_IND) packets and one or more discoverable advertisement indication (ADV_DISCOVER_IND) packets. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of packets formed by of one or more advertising indication (ADV_IND) packets, one or more non-connectable advertising indication (ADV_NONCONN_IND) packets, and one or more discoverable advertisement indication (ADV_DISCOVER_IND) packets. 
     In this situation, if the aforementioned predetermined receiving mode is a mode capable of receiving the aforementioned predetermined data items, then the first Bluetooth transmission circuit  121  and the second Bluetooth transmission circuit  131  may perform the operation  212  to receive the one or more predetermined data items transmitted from the audio playback device  110 . 
     For yet another example, in some embodiments where the aforementioned predetermined transmitting mode is the Broadcast Isochronous Broadcasting mode or the Broadcast Isochronous Synchronization mode, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be one or more BIS PDUs. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be one or more BIG PDUs. Alternatively, the one or more predetermined data items indicated in the aforementioned operation  208  and operation  210  may be a group of PDUs formed by one or more BIS PDUs and one or more BIG PDUs. 
     In this situation, if the aforementioned predetermined receiving mode is an operation mode capable of receiving various PDUs through the BIS logical transports and/or capable of receiving various PDUs through the BIG logical transports, then the first Bluetooth transmission circuit  121  and the second Bluetooth transmission circuit  131  may perform the operation  212  to receive the one or more predetermined data items transmitted from the audio playback device  110 . 
     It can be appreciated from the foregoing elaborations of the aforementioned operation  208 , operation  210 , and operation  212  that the first audio generating device  120  and the second audio generating device  130  can adopt the aforementioned various mechanisms to receive the Bluetooth audio transmission parameters sent by the audio playback device  110  without conducting the Bluetooth pairing procedure with the audio playback device  110 . 
     Afterwards, the first audio generating device  120  may perform the operation  214 , the operation  216 , the operation  218 , and the operation  220 , and the second audio generating device  130  may perform the operation  222 , the operation  224 , the operation  226 , and the operation  228 . 
     In the operation  214 , the first Bluetooth transmission circuit  121  may parse the received one or more predetermined data items to extract one or more Bluetooth audio transmission parameters. As can be appreciated from the foregoing descriptions, the Bluetooth audio transmission parameters extracted by the first Bluetooth transmission circuit  121  would comprise a predetermined indication data, a BIS interval, and the broadcasting timing corresponding to the first audio generating device  120  (e.g., the corresponding relationship between the identification data of the first audio generating device  120  and specific count values). In some embodiments, the Bluetooth audio transmission parameters extracted by the first Bluetooth transmission circuit  121  may further comprise the bandwidth allocated to the first audio generating device  120 . 
     In operations, the first Bluetooth transmission circuit  121  is able to recognize that the audio playback device  110  is the device to be cooperated with the first audio generating device  120  according to the predetermined indication data. In some embodiments, the first Bluetooth transmission circuit  121  will proceed to the operation  216  only in the situation that the extracted Bluetooth audio transmission parameters comprises the aforementioned predetermined indication data. 
     In the operation  216 , the first Bluetooth transmission circuit  121  may acquire an audio broadcasting timing data (hereinafter referred to as a first audio broadcasting timing data for the convenience of distinction) corresponding to the first audio generating device  120  according to the extracted one or more Bluetooth audio transmission parameters. For example, the first Bluetooth transmission circuit  121  may acquire a specific count value generated by the audio playback device  110  based on the broadcasting timing corresponding to the first audio generating device  120  (e.g., the corresponding relationship between the identification data of the first audio generating device  120  and the specific count value). The first Bluetooth transmission circuit  121  may convert the specific count value into a first count value related to a working clock of the first Bluetooth transmission circuit  121  to be the first audio broadcasting timing data corresponding to the first audio generating device  120 . 
     In the operation  218 , the first sound capturing circuit  123  may capture surrounding sounds to generate a corresponding first audio signal. For example, the first sound capturing circuit  123  may capture the voice of a first user located near the first audio generating device  120  to generate the corresponding first audio signal. 
     In the operation  220 , the first audio conversion circuit  125  may generate one or more corresponding Bluetooth LE audio packets according to the first audio signal. For convenience of distinction, the Bluetooth LE audio packets generated by the first audio conversion circuit  125  are hereinafter referred to as first audio packets. In operations, the first audio conversion circuit  125  may utilize the Low Complexity Communication Codec (LC3) to encode the first audio signal, and insert the encoded audio data into one or more first audio packets. In practice, the first audio conversion circuit  125  may utilize other appropriate encoding approaches to encode the first audio signal. 
     In practice, the aforementioned operation  218  or operation  220  may be performed before the operation  214  or the operation  216 , or may be performed at the same time as the aforementioned operation  214  or operation  216 . 
     In the operation  222 , the second Bluetooth transmission circuit  131  may parse the received one or more predetermined data items to extract one or more Bluetooth audio transmission parameters. As can be appreciated from the foregoing descriptions, the Bluetooth audio transmission parameters extracted by the second Bluetooth transmission circuit  131  would comprise a predetermined indication data, a BIS interval, and the broadcasting timing corresponding to the second audio generating device  130  (e.g., the corresponding relationship between the identification data of the second audio generating device  130  and specific count values). In some embodiments, the Bluetooth audio transmission parameters extracted by the second Bluetooth transmission circuit  131  may further comprise the bandwidth allocated to the second audio generating device  130 . 
     In operations, the second Bluetooth transmission circuit  131  is able to recognize that the audio playback device  110  is the device to be cooperated with the second audio generating device  130  according to the predetermined indication data. In some embodiments, the second Bluetooth transmission circuit  131  will proceed to the operation  224  only in the situation that the extracted Bluetooth audio transmission parameters comprises the aforementioned predetermined indication data. 
     In the operation  224 , the second Bluetooth transmission circuit  131  may acquire an audio broadcasting timing data (hereinafter referred to as a second audio broadcasting timing data for the convenience of distinction) corresponding to the second audio generating device  130  according to the extracted one or more Bluetooth audio transmission parameters. For example, the second Bluetooth transmission circuit  131  may acquire a specific count value generated by the audio playback device  110  based on the broadcasting timing corresponding to the second audio generating device  130  (e.g., the corresponding relationship between the identification data of the second audio generating device  130  and the specific count value). The second Bluetooth transmission circuit  131  may convert the specific count value into a second count value related to a working clock of the second Bluetooth transmission circuit  131  to be the second audio broadcasting timing data corresponding to the second audio generating device  130 . 
     In the operation  226 , the second sound capturing circuit  133  may capture surrounding sounds to generate a corresponding second audio signal. For example, the second sound capturing circuit  133  may capture the voice of a second user located near the second audio generating device  130  to generate the corresponding second audio signal. 
     In the operation  228 , the second audio conversion circuit  135  may generate one or more corresponding Bluetooth LE audio packets according to the second audio signal. For convenience of distinction, the Bluetooth LE audio packets generated by the second audio conversion circuit  135  are hereinafter referred to as second audio packets. In operations, the second audio conversion circuit  135  may utilize the Low Complexity Communication Codec (LC3) to encode the second audio signal, and insert the encoded audio data into the one or more second audio packets. In practice, the second audio conversion circuit  135  may utilize other appropriate encoding approaches to encode the second audio signal. 
     In practice, the aforementioned operation  226  or operation  228  may be performed before the operation  222  or the operation  224 , or may be performed at the same time as the aforementioned operation  222  or operation  224 . 
     In the operation  230 , the first audio generating device  120  and the second audio generating device  130  may respectively broadcast the generated audio packets through the BIS logical transport in turn at the time points corresponding to their own audio broadcasting timing data. 
     In operations, the first Bluetooth transmission circuit  121  may begin broadcast of the one or more first audio packets generated by the first audio conversion circuit  125  through a first BIS logical transport according to the aforementioned parameters (such as the BIS interval and/or bandwidth) at a time point corresponding to the first audio broadcasting timing data (i.e., a first time point corresponding to the first count value related to a working clock of the first Bluetooth transmission circuit  121 ). Similarly, the second Bluetooth transmission circuit  131  may begin broadcast of the one or more second audio packets generated by the second audio conversion circuit  135  through a second BIS logical transport according to the aforementioned parameters (such as the BIS interval and/or bandwidth) at a time point corresponding to the second audio broadcasting timing data (i.e., a second time point corresponding to the second count value related to a working clock of the second Bluetooth transmission circuit  131 ). 
     In practice, the aforementioned second BIS logical transport may be the same as the aforementioned first BIS logical transport, or may be different from the aforementioned first BIS logical transport. 
     The first audio generating device  120  and the second audio generating device  130  respectively broadcast their generated audio packets through the BIS logical transports, but the time point at which the first audio generating device  120  begins broadcast of the first audio packets (i.e., the aforementioned first time point) is different from the time point at which the second audio generating device  130  begins broadcast of the second audio packets (i.e., the aforementioned second time point). 
     As shown in  FIG.  2   , the first audio generating device  120  may repeat the operation  218 , the operation  220 , and the operation  230 , so as to continuously capture the surrounding sounds, and generate and broadcast corresponding first audio packets. Similarly, the second audio generating device  130  may repeat the operation  226 , the operation  228 , and the operation  230 , so as to continuously capture the surrounding sounds, and generate and broadcast corresponding second audio packets. 
     On the other hand, the audio playback device  110  may perform the operation  232  of  FIG.  2    to receive the audio packets broadcasted from respective audio generating devices. In this embodiment, for example, the Bluetooth communication circuit  111  receives the first audio packets broadcasted from the first audio generating device  120  through the first BIS logical transport, and receives the second audio packets broadcasted from the second audio generating device  130  through the second BIS logical transport. 
     Please note that the time point at which the first audio generating device  120  begins the broadcast of the first audio packets is different from the time point at which the second audio generating device  130  begins the broadcast of the second audio packets. Therefore, the time point at which the Bluetooth communication circuit  111  receives the first audio packets is different from the time point at which the Bluetooth communication circuit  111  receives the second audio packets. 
     It can be appreciated from the foregoing elaborations of the operation  230  and the operation  232  that the audio playback device  110  can adopt the aforementioned mechanisms to receive the audio packets broadcasted by the first audio generating device  120  and the second audio generating device  130  without conducting the Bluetooth pairing procedure with both the first audio generating device  120  and the second audio generating device  130 . 
     Then, the audio playback device  110  performs the operation  234  to generate and playback corresponding sounds based on received audio packets. In the operation  234 , the control circuit  117  may parse the first audio packets received by the Bluetooth communication circuit  111  to acquire the corresponding first audio data, and may parse the second audio packets received by the Bluetooth communication circuit  111  to acquire the corresponding second audio data. In addition, the audio processing circuit  113  may process the first audio data and the second audio data (e.g., decoding the audio data and/or conducting format conversion) to generate a corresponding sound signal, and may control the audio playback circuit  115  to playback the sound signal generated by the audio processing circuit  113 . 
     In other words, the audio processing circuit  113  may generate a corresponding sound signal based on the contents of the one or more first audio packets broadcasted from the first audio generating device  120  and the contents of the one or more second audio packets broadcasted from the second audio generating device  130 , and may control the audio playback circuit  115  to playback the aforementioned sound signal. 
     It can be appreciated from the forgoing elaborations of  FIG.  2   , the first audio generating device  120  and the second audio generating device  130  of the Bluetooth audio system  100  share the sound playing function of the same audio playback device  110  in a manner similar to time-sharing, but the broadcasting timing and broadcast sequence of the first audio generating device  120  and the second audio generating device  130  are determined by the audio playback device  110  rather than by the first audio generating device  120  or the second audio generating device  130 . 
     Additionally, the first audio generating device  120  and the second audio generating device  130  are enabled to adopt the aforementioned various mechanisms to receive the Bluetooth audio transmission parameters transmitted from the audio playback device  110 , without conducting the Bluetooth pairing procedure with the audio playback device  110 . 
     On the other hand, the audio playback device  110  is enabled to adopt the aforementioned mechanisms to receive the audio packets broadcasted by the first audio generating device  120  and the second audio generating device  130 , without conducting the Bluetooth pairing procedure with the first audio generating device  120  and the second audio generating device  130 . 
     Other audio generating devices in the Bluetooth audio system  100  (e.g., the aforementioned third audio generating device  140  and fourth audio generating device  150 ) may receive the Bluetooth audio transmission parameters transmitted from the audio playback device  110  according to the aforementioned approach adopted by the aforementioned first audio generating device  120  and second audio generating device  130 . Similarly, the audio playback device  110  may receive the audio packets broadcasted by other audio generating devices (e.g., the aforementioned third audio generating device  140  and fourth audio generating device  150 ) according to the aforementioned approach. As a result, the user of the first audio generating device  120 , the user of the second audio generating device  130 , the user of the third audio generating device  140 , and the user of the fourth audio generating device  150  can respectively emit sounds to their corresponding audio generating devices, so that the first audio generating device  120 , the second audio generating device  130 , the third audio generating device  140 , and the fourth audio generating device  150  respectively generate and broadcast corresponding audio packets. On the other hand, the audio playback device  110  may receive the audio packets broadcasted by the first audio generating device  120 , the second audio generating device  130 , the third audio generating device  140 , and the fourth audio generating device  150 , and playback corresponding sounds. 
     In other words, by adopting the method of the foregoing  FIG.  2   , the Bluetooth audio system  100  can be utilized to realize various applications, such as multi-user real-time voice communications, multi-person teaching courses, multi-person instant chorus, or the like. 
     Additionally, since the user of the Bluetooth audio system  100  does not need to spend time in manually performing the Bluetooth pairing procedure between the audio playback device  110  and respective audio generating devices, it is apparent that the structure and operating approach of the disclosed Bluetooth audio system  100  can effectively improve the usage convenience and application flexibility of the Bluetooth audio system  100  in comparison with the manipulating approach of the traditional Bluetooth audio systems. 
     Furthermore, respective audio generating devices in the Bluetooth audio system  100  (e.g., the aforementioned first audio generating device  120 , second audio generating device  130 , third audio generating device  140 , and fourth audio generating device  150 ) may adopt the BLE Audio technology to broadcast the audio packets, and respective audio generating devices may utilize the Low Complexity Communication Codec (LC3) to encode the audio signals. Therefore, in comparison with the traditional Bluetooth system, the aforementioned audio transmission approach adopted by the Bluetooth audio system  100  not only reduces the power consumption of the audio playback device  110  and individual audio generating devices to thereby extend the serving time of the audio playback device  110  and individual audio generating devices, but also effectively improves the overall audio quality of the audio playback device  110 . 
     Please note that the structure of the disclosed Bluetooth audio system  100  is merely an exemplary embodiment, rather than a restriction to the practical implementations of the present disclosure. For example, the number of the audio generating devices in the Bluetooth audio system  100  can be increased or decreased according to practical application requirements, and is not restricted to the number shown in the foregoing embodiment. 
     Certain terms are used throughout the description and the claims to refer to particular components. One skilled in the art appreciates that a component may be referred to as different names. This disclosure does not intend to distinguish between components that differ in name but not in function. In the description and in the claims, the term “comprise” is used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to.” The term “couple” is intended to encompass any indirect or direct connection. Accordingly, if this disclosure mentioned that a first device is coupled with a second device, it means that the first device may be directly or indirectly connected to the second device through electrical connections, wireless communications, optical communications, or other signal connections with/without other intermediate devices or connection means. 
     The term “and/or” may comprise any and all combinations of one or more of the associated listed items. In addition, the singular forms “a,” “an,” and “the” herein are intended to comprise the plural forms as well, unless the context clearly indicates otherwise. 
     Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention indicated by the following claims.