Switching between Multiple Earphone Architectures

Abstract

This disclosure proposes a method (50) for switching from a first Bluetooth® audio source (20) to a second Bluetooth® audio source (21) in a manner suitable for a user experience, e.g., to reduce latency. The method is performed by an audio rendering system (10) including a primary wireless speaker (11) and a secondary wireless speaker (12). The audio rendering system receives a first audio stream from the first audio source by using a first audio topology including a first set of wireless links. Upon receiving a request to switch to the second audio stream using a second audio topology (51), a second set of wireless links is established (52) and then begins receiving the second audio stream (53) while maintaining a connection between the audio rendering system and the first audio source via a wireless link (54) from the first set of wireless links. The wireless speaker may be a wireless earphone, a bookshelf speaker, a floor speaker, an outdoor speaker, a subwoofer, or a headset speaker.

Description

Technical Field

[0001] The present disclosure relates to a method for switching between a first audio source and a second audio source by an audio rendering system including a primary wireless speaker and at least one secondary wireless speaker when the first audio source uses a first audio topology and the second audio source uses a second audio topology different from the first audio topology.

Background Art

[0002] Most current Bluetooth® audio rendering systems use a single approved Bluetooth® audio stream with an associated audio source. In fact, the Bluetooth® protocol, particularly the Advanced Audio Distribution Profile (A2DP), which defines how to transmit an audio stream over a Bluetooth® link, was defined to support only single point-to-point communication between an audio source and an audio rendering system.

[0003] Even a pure wireless earphone, which is a system including two independent Bluetooth® rendering units in the shape of separate earpieces, has only a single approved Bluetooth® audio stream with an audio source such as a smartphone because of such a limitation of the Bluetooth® protocol.

[0004] To maintain compliance with the standard, two audio topologies have been developed to enable both Bluetooth® earpieces to receive audio data.

[0005] The first audio topology is referred to as a transfer audio topology and includes a first approved Bluetooth audio stream with a first Bluetooth earpiece, and the first Bluetooth earpiece relays audio data to a second Bluetooth earpiece using a second approved Bluetooth audio stream.

[0006] The second audio topology is referred to as a snooping audio topology and also includes a first approved Bluetooth audio stream with the first Bluetooth earpiece, and the first earpiece provides information to the second earpiece such that the second earpiece can intercept / snoop on the audio stream transmitted on the wireless link between the audio source and the first earpiece. However, the second earpiece does not directly authenticate the audio source (generally, the second earpiece authenticates the first earpiece, and then the first earpiece authenticates the audio source).

[0007] None of these audio topologies are optimal. The transfer audio topology requires the first earpiece to retransmit the audio data, and the snooping audio topology requires both earpieces to receive the same stereo audio stream (while only playing one of the two audio channels of the stereo audio stream). Since these require additional bandwidth usage, stability is reduced and power consumption increases.

[0008] Also, the number of audio rendering systems receiving an audio stream from a single audio source is limited by these audio topologies.

[0009] Therefore, new audio topologies have been developed to improve the performance of existing audio topologies and support new use cases. These new audio topologies include the following.

[0010] · A dual-stream audio topology that enables both earpieces to obtain a monoral audio stream from the same audio source, thereby reducing power consumption.

[0011] · A broadcast audio topology that provides the ability to obtain the same audio stream from a single audio source to an unlimited number of wireless earphones.

[0012] These audio topologies are currently outside the scope of the Bluetooth® standard and are only available on audio sources that implement these new capabilities as proprietary enhancements.

[0013] Therefore, the audio topology is selected by exchanging the respective audio topology capabilities during the connection setup process between the audio source and the wireless earphones. However, its configuration is always static. This means that it will not change until all audio sources are disconnected from the wireless earphones. Switching between two audio sources is done by disconnecting the first audio source and connecting to the second audio source, but this takes a much longer time and degrades the quality of the user experience.

[0014] The new specification for audio via Bluetooth (registered trademark) Low Energy (BLE) aims to introduce these new audio topologies into the Bluetooth (registered trademark) standard. However, existing Bluetooth (registered trademark) audio rendering systems cannot implement the above standard because they require hardware changes, so the same problem still remains.

[0015] Therefore, a solution is needed to facilitate switching from a first audio source to a second audio source in a manner suitable for the user experience, for example, reducing the waiting time. Introducing new audio topologies into the BLE standard increases the number of use cases where switching between different audio topologies may be required, so the above solution is needed.

Summary of the Invention

[0016] Summary This disclosure aims to propose a solution that overcomes all or some of the above limitations.

[0017] In particular, this disclosure aims to propose a solution for switching from a first audio source to a second audio source in a manner suitable for the user experience.

[0018] Also, this disclosure aims to propose a solution that, in at least some embodiments, enables efficient switching while limiting the power consumption of the audio rendering system.

[0019] For this purpose, according to a first aspect, the present disclosure relates to a method for switching between a first audio source and a second audio source by an audio rendering system comprising a primary wireless speaker and at least one secondary wireless speaker, the audio rendering system receiving a first audio stream from the first audio source by using a first audio topology. The first audio topology corresponds to a first set of wireless links established between the primary wireless speaker, the secondary wireless speaker, and the first audio source. The method · includes receiving a request to switch to receiving a second audio stream from the second audio source by using a second audio topology, the second audio topology corresponding to a second set of wireless links between the primary wireless speaker, the secondary wireless speaker, and the second audio source, the second audio topology being different from the first audio topology, and the method further · includes establishing the second set of wireless links of the second audio topology; and · includes starting to receive the second audio stream; and · includes maintaining the audio rendering system and the first audio source connected by a wireless link of the first set of wireless links while receiving the second audio stream.

[0020] The primary wireless speaker or the secondary wireless speaker can be a wireless earphone, a bookshelf speaker, a floor speaker, an outdoor speaker, a subwoofer, a headset speaker.

[0021] Accordingly, in accordance with the present disclosure, when switching from a first audio source that requires the use of a second audio topology different from the first audio topology used by the first audio source to a second audio source, an audio rendering system (e.g., wireless earphones or a speaker) maintains at least one of a first set of wireless links of the wireless link of the first audio topology while receiving a second audio stream from the second audio source.

[0022] At least one wireless link to be maintained is a wireless link between the first audio source and one of the primary wireless speaker and the secondary wireless speaker such that the first audio source and the audio rendering system remain connected while the audio rendering system receives and plays back the second audio stream from the second audio source.

[0023] In the present disclosure, a wireless link between two entities means that the respective data link layers of the above entities are configured and ready to exchange protocol data units using the wireless physical layer. The data link layer is the protocol layer immediately above the physical layer, and the wireless link can use either the connection mode or the non-connection mode to exchange protocol data units between the above entities.

[0024] In the present disclosure, maintaining a wireless link relates to the case of the connection mode, and means that at least signaling data is repeatedly exchanged via the wireless link to prevent any termination of the wireless link. Accordingly, the first audio topology is assumed to include at least one wireless link maintained in the connection mode between the first audio source and the audio rendering system when switching from the first audio source to the second audio source. [[ID=?]]

[0025] Thanks to at least one wireless link being maintained between the audio rendering system and the first audio source, the first audio source is not disconnected from the audio rendering system. Therefore, it is not necessary to pre-stop the reception of the first audio stream in response to the start of reception of the second audio stream. Thus, it is possible to switch to the reproduction of the second audio stream immediately after or even before stopping the reproduction of the first audio stream, resulting in an improved user experience.

[0026] Also, thanks to at least one wireless link being maintained between the audio rendering system and the first audio source during the reception of the second audio stream, it becomes possible to quickly process a switch-back request (i.e., a request to switch the second audio source back to the first audio source), thereby shortening the switch waiting time and improving the user experience.

[0027] By repeatedly exchanging signaling data via the wireless link, for example, as long as the audio rendering system and the first audio source are within range and / or over a predefined period (e.g., until a predefined timer expires), at least one wireless link can be continuously maintained between the first audio source and the audio rendering system. This may also depend on, for example, each type of audio stream. For example, if the first audio stream corresponds to music streaming and the second audio stream corresponds to a phone call, the wireless link can be maintained throughout the duration of the phone call. This is because when a phone call (the second audio stream) triggered either automatically or manually by a user of the voice rendering system ends, a re-switching request is likely to be received. Further, if the first audio stream corresponds to a phone call and the second audio stream corresponds to music streaming, it is possible to maintain the wireless link between the audio rendering system and the first audio source over a predefined period or the like.

[0028] In certain embodiments, the method for switching may further include one or more of the following features considered alone or in any technically possible combination.

[0029] In certain embodiments, when receiving the second audio stream, only one wireless link of the first set of wireless links is maintained between the primary wireless speaker and the first audio source, and none of the other wireless links of the first set of wireless links are maintained and can actually be actively terminated.

[0030] In such a case, by maintaining a single wireless link, bandwidth usage is reduced, so power consumption and stability are optimized.

[0031] In certain embodiments, when receiving the second audio stream and the audio rendering system has pre-received a third audio stream from a third audio source by using a third audio topology that includes a third set of wireless links, only one wireless link of the third set of wireless links is maintained between the secondary wireless speaker and the third audio source, and none of the other wireless links of the third set of wireless links are maintained.

[0032] Thus, while the audio rendering system is receiving an audio stream from another audio source (the second audio source), if it remains connected to two audio sources (the first audio source and the third audio source), it may be advantageous to use separate wireless speakers (from among the first wireless speaker and the second wireless speaker) to maintain wireless links with the first audio source and the third audio source, respectively, for the purpose of balancing load and power consumption.

[0033] In certain embodiments, when receiving the second audio stream, all of the wireless links of the first set of wireless links of the first audio topology are maintained.

[0034] In such a case, while receiving the second audio stream, the entire first audio topology can be maintained, so power consumption and stability are not optimized, but any re-switching requests will likely be processed very quickly.

[0035] In certain embodiments, the method for switching is · including the step of obtaining a second audio configuration for the primary wireless speaker and the secondary wireless speaker to be used in the second audio topology, the second audio configuration being different from the first audio configuration used in the first audio topology, the method further comprising · including the step of configuring the primary wireless speaker and the secondary wireless speaker with the second audio configuration before starting to receive the second audio stream.

[0036] For example, the first audio configuration and the second audio configuration include · role parameters, · synchronization parameters, · audio encoding parameters, and · channel mapping parameters, including at least one of them.

[0037] In a particular embodiment, the method for switching includes · receiving a request to switch back to receiving the first audio stream from the first audio source, · if not all of the wireless links in the first set of wireless links of the wireless link were maintained, establishing all of the wireless links in the first set of wireless links of the first audio topology, · starting to receive the first audio stream, · while receiving the first audio stream, maintaining the audio rendering system and the second audio source connected by the wireless links in the second set of wireless links.

[0038] As described above, while receiving the first audio stream, it is possible to maintain one or more of the second set of wireless links. It is also possible to maintain all of the wireless links in the second set of wireless links while receiving the first audio stream.

[0039] In certain embodiments, after receiving the switch-back request, the first audio topology is retrieved from data stored in the memory of the audio rendering system or received from the first audio source via a wireless link maintained between the audio rendering system and the first audio source.

[0040] In certain embodiments, the first audio topology is · a transfer audio topology, · a snooping audio topology, and · a dual-stream audio topology, and is one of them, and the second audio topology is · a transfer audio topology, · a snooping audio topology, · a dual-stream audio topology, and · a broadcast audio topology, and is another one of them.

[0041] In certain embodiments, the dual-stream audio topology uses two BLE-connected isochronous stream (CIS) logical transports between the first audio source or the second audio source and their respective primary wireless speaker and secondary wireless speaker.

[0042] In certain embodiments, the broadcast audio topology uses one BLE broadcast isochronous stream (BIS) logical transport between the first audio source or the second audio source and the primary wireless speaker and the secondary wireless speaker.

[0043] In certain embodiments, the method for switching is such that the first audio topology is a transfer audio topology, the second audio topology is a dual stream audio topology, and the first set of wireless links is the wireless link between the secondary wireless speaker and the primary wireless speaker and the wireless link between the first audio source and the primary wireless speaker, · a step of terminating the wireless link between the secondary wireless speaker and the primary wireless speaker; · including a step of changing the role parameters of the primary wireless speaker from master to slave.

[0044] According to a second aspect, the present disclosure relates to a computer program product including instructions that, when executed by an audio rendering system including a primary wireless speaker and at least one secondary wireless speaker, configure the audio rendering system to perform a switching method according to any one of the embodiments of the present invention, and each of the primary wireless speaker and the at least one secondary wireless speaker includes a processing circuit, a wireless communication unit, and an audio rendering unit.

[0045] According to a third aspect, the present disclosure relates to an audio rendering system including a primary wireless speaker and at least one secondary wireless speaker, each of the primary wireless speaker and the secondary wireless speaker comprising a processing circuit, a wireless communication unit, and an audio rendering unit, and the audio rendering system being configured to execute a switching method according to any one of the embodiments of the present invention.

[0046] In certain embodiments, the audio rendering system may further include one or more of the following features, considered individually or in any technically possible combination.

[0047] In certain embodiments, the audio rendering system corresponds to wireless earphones.

[0048] In certain embodiments, the wireless communication unit is a Bluetooth® communication unit, preferably a BLE communication unit.

[0049] Brief Description of the Drawings The present invention can be better understood by reading the following description given as a non-limiting example and will be described with reference to the drawings.

Brief Description of the Drawings

[0050] [Fig. 1] It is a schematic diagram showing various audio topologies between an audio rendering system and an audio source. [Fig. 2] It is a schematic diagram showing an exemplary embodiment of an audio rendering system. [Fig. 3] It is a diagram showing main steps of an exemplary embodiment of a method for switching between various audio sources. [Fig. 4] It is a diagram showing main steps of another exemplary embodiment of a method for switching between various audio sources. [Fig. 5] It is a schematic diagram showing a switching scenario. [Fig. 6] It is a schematic diagram showing a switching scenario. [Fig. 7] It is a diagram showing an exemplary embodiment of the switching from a transfer audio topology to a dual - stream audio topology by an audio rendering system. **DETAILED DESCRIPTION OF THE INVENTION**

[0051] In these figures, the same reference numerals in the figures indicate the same or similar elements. For clarity, the elements shown are not to scale unless otherwise explicitly specified.

[0052] Description of Embodiments In the present disclosure, the audio source can be any device capable of transmitting an audio stream via one or more wireless links. The audio source can be, for example, a smartphone, a laptop, a voice assistant, a tablet, etc.

[0053] The audio rendering system 10 can be any device capable of receiving an audio stream via a wireless link and making the received audio stream content perceptible to the user by playing it back. Also, the audio rendering system 10 includes a primary wireless speaker 11 and at least one secondary wireless speaker 12. Each of these speakers is "wireless" in the sense that the audio data to be played back by each wireless speaker is received via a wireless link. Each of the primary wireless speaker 11 and the secondary wireless speaker 12 can be, for example, a wireless loudspeaker, a wireless earphone or a bone - conduction earpiece, a wireless sub - woofer, etc.

[0054] The present disclosure relates to a method 50 for switching between a first audio source 20 and a second audio source 21 by an audio rendering system 10 when the first audio source 20 and the second audio source 21 use different audio topologies. Each audio topology corresponds to a set of at least one wireless link established between a primary wireless speaker 11, a secondary wireless speaker 12, and the audio sources 20, 21.

[0055] For example, the audio rendering system 10 corresponds to wireless earphones, but the present disclosure is not limited thereto and is applicable to any type of audio rendering system 10 including a primary wireless speaker 11 and at least one secondary wireless speaker 12.

[0056] FIG. 1 schematically shows non-limiting examples of various audio topologies that can be used in the present disclosure.

[0057] Part a) of FIG. 1 shows a first audio topology referred to as a "transfer audio topology". In the transfer audio topology, the set of wireless links includes two wireless links. The first wireless link is established between the audio source 20 and the primary wireless speaker 11. The second wireless link is established between the primary wireless speaker 11 and the secondary wireless speaker 12, enabling the primary wireless speaker 11 to transfer audio data (e.g., a specific audio channel of a stereo audio stream) to be reproduced by the secondary wireless speaker 12 to the secondary wireless speaker 12. In the transfer audio topology, no wireless link is established between the audio source 20 and the secondary wireless speaker 12.

[0058] Part b) of FIG. 1 shows a second audio topology referred to as the "eavesdropping audio topology". In the eavesdropping audio topology, the set of wireless links includes two wireless links. The first wireless link is established between the audio source 20 and the primary wireless speaker 11. The second wireless link is established between the primary wireless speaker 11 and the secondary wireless speaker 12, enabling the primary wireless speaker 11 to provide information regarding the first wireless link to the secondary wireless speaker 12, thereby allowing the secondary wireless speaker 12 to intercept / eavesdrop on the audio stream content transmitted over the first wireless link (represented by the dashed line) without actually being connected to the audio source 20.

[0059] Part c) of FIG. 1 shows a third audio topology referred to as the "dual - stream audio topology". In the dual - stream audio topology, the set of wireless links includes two wireless links. The first wireless link is established between the audio source 20 and the primary wireless speaker 11. The second wireless link is established between the audio source 20 and the secondary wireless speaker 12. Each of the primary wireless speaker 11 and the secondary wireless speaker 12 receives its own audio data (e.g., a particular audio channel of a stereo audio stream) via a separate point - to - point wireless link with the audio source 20.

[0060] Part d) of FIG. 1 shows a fourth audio topology, referred to as a "broadcast audio topology". In the broadcast audio topology, the set of wireless links generally comprises a single wireless link that uses the disconnected mode. Thus, in the broadcast audio topology, the audio source 20 and the audio rendering system 10 are not necessarily connected at the data link layer level. From the perspective of the audio source 20, only a single data link layer configuration is used to transmit protocol data units to both the primary wireless speaker 11 and the secondary wireless speaker 12 via different respective wireless paths. Each of the primary wireless speaker 11 and the secondary wireless speaker 12 receives the entire audio stream via a separate wireless path from the audio source 20. Compared to the dual-stream audio topology, there is only one transmission by the audio source 20 that can be received by a plurality of receivers (not only the primary wireless speaker 11 and the secondary wireless speaker 12) via separate wireless paths of the point-to-multipoint architecture.

[0061] FIG. 2 schematically shows the main components of an exemplary embodiment of the audio rendering system 10.

[0062] As shown in FIG. 2, the audio rendering system 10 comprises a primary wireless speaker 11 and at least one secondary wireless speaker 12. For example, each of the primary wireless speaker 11 and the secondary wireless speaker 12 can be a wireless loudspeaker, a wireless earpiece, a wireless subwoofer, etc.

[0063] Each of the primary wireless speaker 11 and the secondary wireless speaker 12 also comprises a wireless communication unit 110, 120, a processing circuit 111, 121, and an audio rendering unit 112, 122.

[0064] Each of the wireless communication units 110 and 120 is used to establish a wireless link with an audio source and corresponds to a high-frequency circuit including components (such as an antenna, an amplifier, a local oscillator, a mixer, analog and / or digital filters, etc.) that are considered to be known to those skilled in the art. The wireless communication units 110 and 120 implement at least one wireless communication protocol. For example, the wireless communication units 110 and 120 may include at least one of the following.

[0065] · A Bluetooth (registered trademark) communication unit, · An Ultra Wide-Band (UWB) communication unit, · A Wi-Fi (registered trademark) communication unit, · A ZigBee (registered trademark) communication unit, etc.

[0066] For example, each of the processing circuits 111 and 121 includes one or more processors and storage means (such as a magnetic hard disk, a solid state disk, an optical disk, an electronic memory, etc.). The storage means stores a computer program product in the form of a set of program code instructions to be executed to perform all or part of the steps of the method 50 for switching between the first audio source 20 and the second audio source 21. Alternatively, or in combination with these, the processing circuits 111 and 121 may include one or more programmable logic circuits (such as FPGA, PLD, etc.) and / or one or more application specific integrated circuits (ASIC) and / or a set of individual electronic components that are adapted to perform all or part of the above steps of the switching method 50.

[0067] Each audio rendering unit 112 and 122 can be any suitable device adapted to make the audio stream audible to the user. For this reason, each audio rendering unit 112 and 122 may be, for example, any type of electroacoustic transducer.

[0068] The processing circuits 111, 121, the wireless communication units 110, 120, and the audio rendering units 112, 122 of the audio rendering system 10 form a set of means configured by software (a specific computer program product) and / or by hardware (processors, FPGAs, PLDs, ASICs, individual electronic components, high-frequency circuits, electroacoustic transducers, etc.) to implement the steps of the switching method 50 described below.

[0069] In the following description, the wireless communication units 110, 120 of the audio rendering system 10 are regarded as, without limitation, Bluetooth (registered trademark) communication units. Accordingly, the wireless link with the audio source established by the audio rendering system 10 and the wireless link established between the primary wireless speaker 11 and the secondary wireless speaker 12 are regarded as Bluetooth (registered trademark) links.

[0070] In the present disclosure, an audio stream corresponds to application-level data representing an audio signal, and can be, for example, a bitstream generated from an audio streaming application, a locally stored music file read by an application, an output of an audio server, etc. The audio stream content corresponds to useful data (opposed to metadata) representing the audio data actually reproduced by the audio rendering system 10. The audio stream content can include one or more audio channels (for example, monoral music or stereo music, etc.).

[0071] The Bluetooth (registered trademark) audio stream refers to the Bluetooth (registered trademark) term and specifies the logical communication for streaming application-level audio stream content between an audio source and an audio rendering system 10. The Bluetooth (registered trademark) audio stream uses Bluetooth (registered trademark) packets on a single Bluetooth (registered trademark) logical link (multiple Bluetooth (registered trademark) audio streams can use the same logical link).

[0072] For example, a dual-stream audio topology may use two Bluetooth (registered trademark) audio streams using a BLE connection-oriented isochronous stream (CIS) logical transport between the audio source and each of the primary wireless speaker 11 and the secondary wireless speaker 12. As an example, a broadcast audio topology may use one Bluetooth (registered trademark) audio stream using one BLE broadcast isochronous stream (BIS) logical transport between the audio source and the primary wireless speaker 11 and the secondary wireless speaker 12.

[0073] Also, as described above, the audio rendering system 10 is said to be "connected" by a wireless link to the audio source when each data link layer is configured and ready to exchange protocol data units using the connection mode.

[0074] Also, when audio stream content is wirelessly transmitted from an audio source to the audio rendering system 10 and the audio rendering system 10 processes the received wireless signal to extract the audio stream content transmitted by the audio source, the audio stream is referred to as "active". When none of the audio stream content is wirelessly transmitted, or when the audio stream content is wirelessly transmitted but not extracted by the audio rendering system 10 from the received wireless signal, the audio stream is referred to as "inactive".

[0075] FIG. 3 schematically shows the main steps of an exemplary embodiment of a method 50 for switching between a first audio source 20 and a second audio source 21. The above steps are executed by the audio rendering system 10.

[0076] As shown by FIG. 3, the switching method 50 includes a step 51 of receiving a request to switch to receiving a second audio stream from a second audio source 21 by using a second audio topology including a second set of wireless links between the primary wireless speaker 11, the secondary wireless speaker 12, and the second audio source 21.

[0077] The second audio topology is different from the first audio topology and can be determined based on various parameters.

[0078] For example, the second audio topology, in some embodiments, may be determined based on the audio source capabilities of the second audio source 21. In that case, when establishing the first wireless link between the audio rendering system 10 and the second audio source 21, the second audio source 21 may provide a list of supported audio topologies. This list may be stored in the memory of the audio rendering system 10 for later use. When a request to switch to the second audio source 21 is received, this list may be retrieved and the second audio topology may be selected from among the supported audio topologies. According to another example, the second audio source 21 may explicitly request to use a particular audio topology as the second audio topology.

[0079] According to yet another example, the second audio topology, in some embodiments, may be determined based on the audio stream capabilities. In practice, the second audio stream may require using a particular audio topology as the second audio topology. In that case, when a request to switch to the second audio source 21 is received, the audio rendering system 10 may determine to select this particular audio topology as the second audio topology because the second audio stream requires using this particular audio topology.

[0080] Based on the above description, it is understood that the second audio topology may be determined when, for example, a first wireless link is established between the second audio source 21 and the audio rendering system 10 (by reading the audio source capabilities of the second audio source 21), or when a new audio stream is detected to be available (e.g., in a new audio stream indication broadcast message or unicast request).

[0081] Also, it is emphasized that the switching request may be triggered by the second audio source 21 or the first audio source 20, for example, based on the respective priorities of the audio streams available from various audio sources connected to the audio rendering system 10, may be manually triggered by the user, or may be automatically triggered by the audio rendering system 10.

[0082] When the audio rendering system 10 receives a switching request, the switching method 50 includes a step 52 of establishing all the wireless links in the second set of wireless links of the second audio topology so as to be able to receive the second audio stream by using the second audio topology.

[0083] Note that in some cases, the switch from the first audio topology to the second audio topology may require not only establishing a new set of wireless links, but also changing the audio configuration of the primary wireless speaker 11 and the secondary wireless speaker 12. The audio configurations of the primary wireless speaker 11 and the secondary wireless speaker 12 correspond to the values of the parameters that affect the behavior of the audio rendering system 10 on the established wireless link. For example, the first audio configuration and the second audio configuration (each associated with the first audio topology and the second audio topology respectively) include at least one of the following parameters.

[0084] · Role parameter, · Synchronization parameter, · Audio encoding parameter, · Channel mapping parameter, etc.

[0085] The role parameter indicates whether the primary wireless speaker 11 or the secondary wireless speaker 12 operates as a "master" or as a "slave" on each wireless link established by the audio rendering system 10. For example, in a transfer audio topology, the primary wireless speaker 11 involved in both wireless links of a set of wireless links may function as a "master" on both of the above wireless links. Further, the secondary wireless speaker 12 may function as a "slave" on the single wireless link it is involved in. In a dual-stream audio topology, both the primary wireless speaker 11 and the secondary wireless speaker 12 may function as "slaves" on a wireless link with an audio source or the like.

[0086] The synchronization parameter indicates how the audio data reproduced by the primary wireless speaker 11 and the secondary wireless speaker 12 are synchronized in terms of time. For example, in a transfer audio topology, the primary wireless speaker 11 first evaluates a streaming clock value and then converts it into a value of a local clock synchronized between the primary wireless speaker 11 and the secondary wireless speaker 12, and may use this to stamp a time stamp on the audio data transferred to the secondary wireless speaker 12. In a dual-stream audio topology, since the Bluetooth (registered trademark) clock can be directly used to stamp a time stamp on the audio data by the audio source, conversion to a local clock value is unnecessary.

[0087] Audio encoding parameters indicate which type of audio codec is used. For example, a dual-stream audio topology may use a higher bitrate audio codec. This is because, for example, each of the primary wireless speaker 11 and the secondary wireless speaker 12 receives only one of the two audio channels of the stereo audio stream. Further, a transfer audio topology may use a lower bitrate audio codec. The type of audio codec used may also depend on the capabilities of the audio source.

[0088] Channel mapping parameters indicate how audio channels are mapped. For example, in a transfer audio topology, the primary wireless speaker 11 receives both audio channels of the stereo audio stream, plays only its own audio channel, and transfers the other audio channel to the secondary wireless speaker 12. In a dual-stream audio topology, each of the primary wireless speaker 11 and the secondary wireless speaker 12 receives only the monoral audio stream corresponding to its own audio channel of the stereo audio stream. In a broadcast audio topology, each of the primary wireless speaker 11 and the secondary wireless speaker 12 receives the stereo audio stream but plays only its own audio channel of the stereo audio stream.

[0089] Of course, other parameters may be included in the audio configuration in combination with or instead of the above parameters.

[0090] Therefore, switching from the first audio source 20 to the second audio source 21 may also require switching from the first audio configuration to the second audio configuration. The switching method 50 may, if necessary, · Obtaining a second audio configuration for the primary wireless speaker 11 and the second wireless speaker 12 to be used in the second audio topology; · Configuring the primary wireless speaker 11 and the secondary wireless speaker 12 in the second audio configuration before starting to receive the second audio stream; It may include any additional optional steps.

[0091] When the second audio topology becomes operational, the switching method 50 includes a step 53 of starting to receive the second audio stream for playing the second audio stream by the audio rendering system 10.

[0092] While the audio rendering system 10 is receiving the second audio stream from the second audio source 21, the switching method 50 includes a step 54 of maintaining at least one of the first set of wireless links so that the audio rendering system 10 and the first audio source 20 remain connected.

[0093] In some embodiments, only a single wireless link between the first audio source and one of the primary wireless speaker 11 and the secondary wireless speaker 12 can be maintained. In other embodiments, it is possible to maintain two or more wireless links, including maintaining all of the first set of wireless links so that the first audio topology coexists with the second audio topology. It is also possible to vary the number of maintained wireless links over time. For example, initially, all of the first set of wireless links are maintained for a predetermined period, and then some of the wireless links are terminated until only one of the first set of wireless links is maintained between the first audio source 20 and the audio rendering system 10, etc.

[0094] Thanks to the first audio topology being at least partially maintained, the first audio stream can be maintained active for longer than in the case of prior art solutions, thereby improving the user experience. Also, any re-switching requests to switch back to receiving the audio stream from the first audio source will be received and processed more quickly than in the case of prior art solutions.

[0095] FIG. 4 schematically shows the main steps of an exemplary embodiment of the switching method 50. As shown in FIG. 4, the switching method 50 includes all of the steps shown in FIG. 3.

[0096] At some point after starting to receive the second audio stream from the second audio source 21, the switching method 50 includes a step 55 of receiving, by the audio rendering system 10, a request to switch back to receiving the first audio stream from the first audio source 20. As described above for the switching request (step 51), the re-switching request may be triggered by the second audio source 21 or the first audio source 20, for example, based on the respective priorities of the available audio streams from the various audio sources connected to the audio rendering system 10, may be manually triggered by the user, or may be automatically triggered by the audio rendering system 10.

[0097] As described above, at least one wireless link of the first set of wireless links of the first audio topology is maintained. If all wireless links of the first set of wireless links are maintained, there is no need to re-establish the wireless links of the first audio topology. If not all wireless links of the first set of wireless links are maintained, the switching method 50 includes step 56 of establishing all wireless links of the first set of wireless links of the first audio topology. During this step, the wireless links that are not maintained in the first set of wireless links are re-established.

[0098] Note that the first audio topology defined by the first set of wireless links may be stored in the memory of the audio rendering system 10. Thus, when a switch-back request is received, the first audio topology is quickly determined by being retrieved within the memory. Alternatively, the first audio topology may also be received from the first audio source 20 via a wireless link maintained between the audio rendering system 10 and the first audio source 20. In practice, thanks to the wireless link being maintained at the first audio source 20, this information can also be retrieved quickly.

[0099] As described above, in order to enable the first audio topology to operate, it may also be necessary to change the audio configurations of the primary wireless speaker 11 and the secondary wireless speaker 12. Preferably, the first audio configuration used with the first audio source 20 prior to switching to the second audio source 21 is stored in the memory of the audio rendering system 10. In that case, the first audio configuration can be retrieved from the memory to configure the primary wireless speaker 11 and the secondary wireless speaker 12 more quickly. Alternatively, the first audio configuration may also be received from the first audio source 20 via a wireless link maintained between the audio rendering system 10 and the first audio source 20.

[0100] When the first audio topology becomes operable, the switching method 50 includes a step 57 of starting to receive the first audio stream from the first audio source 20 (i.e., the first audio stream becomes active).

[0101] Preferably, the switching method 50 includes an optional step 58 of maintaining the audio rendering system 10 and the second audio source 21 connected by at least one wireless link of the second set of wireless links while receiving the first audio stream. All that has been described above regarding maintaining at least one wireless link of the first set of wireless links also applies here. In particular, it is possible to maintain all the wireless links of the second set of wireless links of the second audio topology to facilitate a return switch to the second audio source 21 if necessary.

[0102] The present disclosure relates to any switch from a first audio topology to a second audio topology different from the first audio topology. However, the following use cases are particularly relevant.

[0103] · The first audio topology is a transfer audio topology, and the second audio topology is a dual - stream audio topology or a broadcast audio topology.

[0104] · The first audio topology is a snooping audio topology, and the second audio topology is a dual - stream audio topology or a broadcast audio topology.

[0105] Figure 5 schematically shows the switching from a transfer audio topology to a dual - stream audio topology.

[0106] In part a) of Figure 5, the audio rendering system 10 (wireless earphones) receives a first audio stream from a first audio source 20 (laptop) using a transfer audio topology. When using the transfer audio topology, the first audio source 20 is connected to the primary wireless speaker 11 by a first wireless link, and the primary wireless speaker 11 is connected to the secondary wireless speaker 12 by a second wireless link.

[0107] In part b) of Figure 5, the audio rendering system 10 switches to receive a second audio stream from a second audio source 21 (smartphone) using a dual - stream audio topology. When using the dual - stream audio topology, the first audio source 20 is connected to the primary wireless speaker 11 by a first wireless link and to the secondary wireless speaker 12 by a second wireless link. As shown in part b) of Figure 5, while the audio rendering system 10 is receiving the second audio stream, the wireless links of the transfer audio topology (represented by dotted lines) are maintained.

[0108] Figure 6 schematically shows the switching from a dual-stream audio topology to a broadcast audio topology.

[0109] In part a) of Figure 6, an audio rendering system 10 (wireless earphone) receives a first audio stream from a first audio source 20 (smartphone) using a dual-stream audio topology. When using a dual-stream audio topology, the first audio source 20 is connected to a primary wireless speaker 11 by a first wireless link and to a secondary wireless speaker 12 by a second wireless link.

[0110] In part b) of Figure 6, the audio rendering system 10 switches to receive a second audio stream from a second audio source 21 (such as a fire alarm) using a broadcast audio topology. As shown in part b) of Figure 6, while the audio rendering system 10 is receiving the second audio stream, the wireless links of the dual-stream audio topology (represented by dotted lines) are maintained.

[0111] Figure 7 represents an exemplary embodiment showing how a switching method 50 can be implemented in the case of switching from a transfer audio topology at a first audio source (laptop) to a dual-stream audio topology at a second audio source 21 (smartphone).

[0112] First, the first audio stream from the first audio source 20 is active, and thus, the first audio stream content is transmitted by the first audio source 20 and received by the audio rendering system 10 (wireless earphone) (see S70). Next, the second audio source 21 establishes a wireless link with the primary wireless speaker 11 (see S71), and a switching request indicating that the audio rendering system 10 should switch to the second audio source 21 is received (see S72). In the illustrated example, based on the received switching request, the audio rendering system 10 requests the first audio source 20 to stop transmitting the first audio stream so that the first audio stream becomes inactive (see S73). Next, the audio rendering system 10 determines the second audio topology, for example, based on the audio source capabilities of the second audio source 21 pre-stored by the audio rendering system 10 and / or received from the second audio source 21, or based on the audio stream capabilities of the second audio stream, etc. (see S74). Next, the audio rendering system 10 terminates the wireless link of the transfer audio topology between the secondary wireless speaker 12 and the primary wireless speaker 11 (see S75). Also, the audio rendering system 10 and the first audio source 20 change the role of the primary wireless speaker 11 on the wireless link of the transfer audio topology between the first audio source 20 and the primary wireless speaker 11. The role of the primary wireless speaker 11 is changed from "master" to "slave", and the wireless link of the transfer audio topology between the first audio source 20 and the primary wireless speaker 11 is maintained (see S76). Next, the audio rendering system 10 establishes the wireless link of the set of wireless links of the dual-stream audio topology with the second audio source 21.Since the primary wireless speaker 11 is already connected to the second audio source 21 by a wireless link, only the wireless link between the second audio source 21 and the secondary wireless speaker 12 is established (see S77). Next, the audio rendering system 10 configures the primary wireless speaker 11 and the secondary wireless speaker 12 in an audio configuration to be used in a dual-stream audio topology (see S78). Finally, with the first audio source 20 and the primary wireless speaker 11 remaining connected by the wireless link of the transfer audio topology, a second audio stream is activated such that second audio stream content is transmitted by the second audio source 21 and processed by the audio rendering system 10 (see S79).

[0113] Note that the order of operations represented in FIG. 7 is exemplary, and other orders are possible. For example, in FIG. 7, the first audio stream is deactivated immediately after the switch request is received. However, the first audio stream may be deactivated later, and may be deactivated after the second audio stream is activated (especially when the first audio topology is fully maintained and coexists with the second audio topology).

[0114] Note that in some embodiments, it is possible to have at most one active audio stream. In that case, in a certain “break before make” approach, the first audio stream needs to be deactivated before the second audio stream is activated. Thus, the audio rendering system 10 stops receiving the first audio stream before starting to receive the second audio stream. Such an approach is advantageous in that it can reduce the power consumption and processing of the audio rendering system 10.

[0115] In the present disclosure, it should be noted that stopping the reception of an audio stream means that the audio rendering system stops extracting the audio stream content from the wireless signal received from the audio source. This may imply that, in the case of a wireless link using the connection mode, signaling is exchanged between the audio source and the audio rendering system 10 to ensure that the audio source stops transmitting the audio stream content to the audio rendering system 10. For example, the audio rendering system 10 may send an audio / video distribution transport protocol (AVDTP) pause request to the audio source, and in response, the audio source may pause the Bluetooth (registered trademark) audio stream of the (application level) audio stream content so that the reception of the audio stream content is stopped. Considering the broadcast audio topology, the transmission of the audio stream content by the audio source is not stopped, but the audio rendering system 10 only needs to stop processing the wireless signal to extract the audio stream content broadcast by the audio source.

[0116] Also, starting to receive an audio stream means that the audio rendering system starts extracting the audio stream content from the radio signal received from the audio source. Naturally, this may imply that, in the case of a wireless link using a connection mode, signaling is exchanged between the audio source and the audio rendering system 10 to ensure that the audio source starts transmitting the audio stream content to the audio rendering system 10. For example, the audio rendering system 10 may start receiving the audio stream content by transmitting an AVDTP start request to the audio source (in response to which, a Bluetooth (registered trademark) audio stream is started and the transmission of the application-level audio stream content is started), and by starting to extract the audio stream content from the received radio signal. Considering the broadcast audio topology, since the transmission of the audio stream content by the audio source remains continuous, the audio rendering system 10 only needs to start processing the radio signal to extract the audio stream content broadcast by the audio source.

[0117] In other embodiments, it is possible to activate at least temporarily two or more audio streams simultaneously. In that case, only one audio stream content can be played at that time. Therefore, the audio rendering system 10 stops playing the first audio stream content before starting to play the second audio stream content by the audio rendering units 112, 122. The first audio stream content further received and extracted by the audio rendering system 10 is discarded, for example, without being played by the audio rendering units 112, 122. However, in other embodiments, it is also possible to play the first audio stream content and the second audio stream content simultaneously at least temporarily, for example, by ducking the first audio stream content with the second audio stream content.

[0118] It is emphasized that the present invention is not limited to the above-described exemplary embodiments. Modifications of the above-described exemplary embodiments are also within the scope of the present invention.

[0119] For example, these exemplary embodiments have been described with reference to the case where the wireless link is a Bluetooth® link. However, in other embodiments, it is also possible to use other wireless communication protocols. In some embodiments, the audio rendering system 10 can support even multiple wireless communication protocols and can use various wireless communication protocols to wirelessly connect to various devices.

Claims

1. A method (50) for switching between a first audio source (20) and a second audio source (21) by an audio rendering system (10) comprising a primary wireless speaker (11) and at least one secondary wireless speaker (12), wherein the audio rendering system (10) receives a first audio stream from the first audio source (20) by using a first audio topology, the first audio topology corresponding to a first set of wireless links established between the primary wireless speaker (11), the secondary wireless speaker (12), and the first audio source (20), the method (50) comprising: - Receiving (51) a request to switch to receiving a second audio stream from the second audio source (21) by using a second audio topology, the second audio topology corresponding to a second set of wireless links between the primary wireless speaker (11), the secondary wireless speaker (12), and the second audio source (21), the second audio topology being different from the first audio topology, the method (50) further comprising: - Establishing (52) the second set of wireless links of the second audio topology; - Starting (53) reception of the second audio stream; - While receiving the second audio stream, maintaining (54) the audio rendering system (10) and the first audio source (20) connected by a wireless link of the first set of wireless links, The method (50) wherein when receiving the second audio stream, only one wireless link of the first set of wireless links is maintained between the primary wireless speaker (11) and the first audio source (20), and none of the other wireless links of the first set of wireless links are maintained.

2. When receiving the second audio stream, and when the audio rendering system (10) has previously received a third audio stream from a third audio source by using a third audio topology corresponding to a third set of wireless links, only one wireless link of the third set of wireless links is maintained between the secondary wireless speaker (12) and the third audio source, and none of the other wireless links of the third set of wireless links are maintained. The method (50) according to claim 1.

3. When receiving the second audio stream, all of the wireless links of the first set of wireless links of the first audio topology are maintained. The method (50) according to claim 1.

4. A method (50) for switching between a first audio source (20) and a second audio source (21) by an audio rendering system (10) comprising a primary wireless speaker (11) and at least one secondary wireless speaker (12), wherein the audio rendering system (10) receives a first audio stream from the first audio source (20) by using a first audio topology, and the first audio topology corresponds to a first set of wireless links established between the primary wireless speaker (11), the secondary wireless speaker (12), and the first audio source (20), and the method (50) comprises - a step (51) of receiving a request for switching to receive a second audio stream from the second audio source (21) by using a second audio topology, the second audio topology corresponding to a second set of wireless links between the primary wireless speaker (11), the secondary wireless speaker (12), and the second audio source (21), the second audio topology being different from the first audio topology, and the method (50) further comprises - a step (52) of establishing the second set of wireless links of the second audio topology; - starting the reception of said second audio stream (53); - maintaining (54) the audio rendering system (10) and the first audio source (20) connected by a wireless link of the first set of wireless links while receiving the second audio stream; obtaining a second audio configuration of the primary wireless speaker (11) and the secondary wireless speaker (12) to be used in the second audio topology, the second audio configuration being different from the first audio configuration used in the first audio topology; and A method (50) comprising configuring the primary wireless speaker (11) and the secondary wireless speaker (12) in the second audio configuration before starting to receive the second audio stream.

5. The first audio configuration and the second audio configuration are: Role parameters, - synchronization parameters, audio coding parameters, - channel mapping parameters, The method (50) of claim 4, comprising at least one of:

6. A method (50) for switching between a first audio source (20) and a second audio source (21) by an audio rendering system (10) comprising a primary wireless speaker (11) and at least one secondary wireless speaker (12), wherein the audio rendering system (10) receives a first audio stream from the first audio source (20) by using a first audio topology, the first audio topology corresponding to a first set of wireless links established between the primary wireless speaker (11), the secondary wireless speaker (12), and the first audio source (20), the method (50) comprising: receiving (51) a request to switch to receiving a second audio stream from the second audio source (21) by using a second audio topology, the second audio topology corresponding to a second set of wireless links between the primary wireless speaker (11), the secondary wireless speaker (12), and the second audio source (21), the second audio topology being different from the first audio topology, the method (50) further comprising: - establishing (52) a second set of said wireless links of said second audio topology; - starting the reception of said second audio stream (53); - maintaining (54) the audio rendering system (10) and the first audio source (20) connected by a wireless link of the first set of wireless links while receiving the second audio stream; receiving (55) a request to switch back to receiving the first audio stream from the first audio source (20); - if not all wireless links of the first set of wireless links have been maintained, establishing (56) all wireless links of the first set of wireless links of the first audio topology; - starting the reception of said first audio stream (57); - maintaining (58) the audio rendering system (10) and the second audio source (21) connected by a wireless link from the second set of wireless links while receiving the first audio stream.

7. 7. The method of claim 6, wherein after receiving a switch back request, the first audio topology is retrieved from data stored in a memory of the audio rendering system or is received from the first audio source via the wireless link maintained between the audio rendering system and the first audio source.

8. A method (50) for switching between a first audio source (20) and a second audio source (21) by an audio rendering system (10) comprising a primary wireless speaker (11) and at least one secondary wireless speaker (12), wherein the audio rendering system (10) receives a first audio stream from the first audio source (20) by using a first audio topology, the first audio topology corresponding to a first set of wireless links established between the primary wireless speaker (11), the secondary wireless speaker (12), and the first audio source (20), the method (50) comprising: receiving (51) a request to switch to receiving a second audio stream from the second audio source (21) by using a second audio topology, the second audio topology corresponding to a second set of wireless links between the primary wireless speaker (11), the secondary wireless speaker (12), and the second audio source (21), the second audio topology being different from the first audio topology, the method (50) further comprising: - establishing (52) a second set of said wireless links of said second audio topology; - starting the reception of said second audio stream (53); maintaining (54) the audio rendering system (10) and the first audio source (20) connected by a wireless link of the first set of wireless links while receiving the second audio stream; The first audio topology comprises: - forward audio topology, - eavesdropping audio topology, and - Dual-stream audio topology, and the second audio topology is one of: - the transport audio topology; - the eavesdropping audio topology, the dual-stream audio topology; and Broadcast audio topology, is another one of The first audio topology is the transfer audio topology, the second audio topology is the dual - stream audio topology, and when the first set of wireless links is a wireless link between the secondary wireless speaker (12) and the primary wireless speaker (11) and a wireless link between the first audio source (20) and the primary wireless speaker (11), - ending the wireless link between the secondary wireless speaker (12) and the primary wireless speaker (11); - changing the role parameter of the primary wireless speaker (11) from master to slave, the method (50).

9. - The dual - stream audio topology uses two Bluetooth (R) low - energy connection - type isochronous stream logical transports between the first audio source or the second audio source (20, 21) and the respective primary wireless speaker and the secondary wireless speaker, and / or, - The broadcast audio topology uses one Bluetooth (R) low - energy broadcast isochronous stream logical transport between the first audio source or the second audio source (20, 21) and the primary wireless speaker and the secondary wireless speaker (11, 12), the method (50) according to claim 8.

10. A computer program product comprising instructions which, when executed by an audio rendering system (10) comprising a primary wireless speaker (11) and at least one secondary wireless speaker (12), configure the audio rendering system (10) to perform the method according to any one of claims 1 - 9, wherein each of the primary wireless speaker (11) and the at least one secondary wireless speaker (12) comprises a processing circuit (111, 121), a wireless communication unit (110, 120), and an audio rendering unit (112, 122), the program.

11. An audio rendering system (10) including a primary wireless speaker (11) and at least one secondary wireless speaker (12), wherein each of the primary wireless speaker and the secondary wireless speaker (11, 12) comprises a processing circuit (111, 121), a wireless communication unit (110, 120), and an audio rendering unit (112, 122), and the audio rendering system (10) is configured to execute the method according to any one of claims 1 to 9.

12. The audio rendering system (10) according to claim 11, wherein the audio rendering system (10) corresponds to wireless earphones.

13. The audio rendering system (10) according to claim 11 or 12, wherein the wireless communication unit (110, 120) is a Bluetooth (registered trademark) communication unit.

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