Audio transmission method, playing device, true wireless playing device and system

Abstract

The invention relates to the technical field of communication interaction, in particular to an audio transmission method, playing equipment, true wireless playing equipment and a system. The audio transmission method comprises the following steps: receiving a Bluetooth downlink frame sent by sound source equipment; verifying the Bluetooth downlink frame through a plurality of detection stages in sequence; determining an audio packet forwarding direction; if the Bluetooth downlink frame is forwarded to the second playing device, in response to the situation that the access code detection fails and the like, stopping detecting the Bluetooth downlink frame, and sending at least one second historical audio packet in a second audio packet set to the second playing device based on the second audio packet set before receiving a next Bluetooth downlink frame sent by the sound source device; and if the first audio packet set is forwarded to the first playing device, in response to the situation that the access code detection fails and the like, stopping detecting the Bluetooth downlink frame, and before receiving the next Bluetooth downlink frame sent by the sound source device, trying to receive a first historical audio packet sent by the second playing device based on the first audio packet set. The capability of receiving the audio packet is enhanced, and the power consumption is saved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of communication interaction, and in particular, to an audio transmission method, a playback device, a true wireless playback device, and an audio transmission system. BACKGROUND

[0002] For the application scenario of audio playback through the true wireless playback device, the true wireless playback device can receive an audio packet sent by the sound source device through a Bluetooth downlink frame based on a Bluetooth connection between the true wireless playback device and the sound source device, and then perform audio playback.

[0003] In the related art, the audio packet sent by the sound source device through the Bluetooth downlink frame needs to receive an acknowledgment signal (ACK) fed back by the true wireless playback device before the next audio packet is sent through the next Bluetooth downlink frame. If the sound source device receives a negative acknowledgment signal (NACK) or does not receive feedback, the sound source device will resend the audio packet through the next Bluetooth downlink frame until the acknowledgment signal fed back is received.

[0004] However, if the Bluetooth connection quality between the sound source device and the true wireless playback device is poor, the sound source device will resend the audio packet a large number of times, affecting the audio playback quality. Moreover, because the sound source device resends the audio packet a large number of times, the number of communications between the devices also increases, increasing the power consumption of the true wireless playback device, shortening the use time of the true wireless playback device, and affecting the user experience. SUMMARY

[0005] To overcome the problems in the related art, the exemplary embodiments of the present disclosure provide an audio transmission method applied to a first playback device in a true wireless playback device, the first playback device being connected with a second playback device in the true wireless playback device through a second Bluetooth connection, and receiving an audio packet through a first Bluetooth connection established with an audio source device or through listening to the first Bluetooth connection established by the second playback device and the audio source device; the method comprises: receiving a Bluetooth downlink frame sent by the audio source device, wherein the Bluetooth downlink frame is used to transmit the audio packet; sequentially verifying the Bluetooth downlink frame through a plurality of detection stages, wherein the plurality of detection stages comprise: an access code detection stage, a packet header detection stage; determining an audio packet forwarding direction identified by a current forwarding state flag; if the audio packet forwarding direction is to forward to the second playback device, in response to the Bluetooth downlink frame access code detection failure, and / or packet header detection failure, and / or packet header field analysis determining that the Bluetooth downlink frame has no payload, stopping continuing to detect the Bluetooth downlink frame, and before receiving the next Bluetooth downlink frame sent by the audio source device, sending at least one second historical audio packet in a second audio packet set to the second playback device based on the second audio packet set, wherein the second audio packet set is a second historical audio packet sequence that the second playback device has not successfully received from the audio source device; if the audio packet forwarding direction is to forward to the first playback device, in response to the Bluetooth downlink frame access code detection failure, and / or packet header detection failure, and / or packet header field analysis determining that the Bluetooth downlink frame has no payload, stopping continuing to detect the Bluetooth downlink frame, and before receiving the next Bluetooth downlink frame sent by the audio source device, attempting to receive at least one first historical audio packet in a first audio packet set sent by the second playback device based on the first audio packet set, wherein the first audio packet set is a first historical audio packet sequence that the first playback device has not successfully received from the audio source device.

[0006] In some embodiments, determining the audio packet forwarding direction identified by the current forwarding state flag comprises: receiving a first cumulative number sent by the second playback device, wherein the first cumulative number is the number of first historical audio packets in the first audio packet set; if the first cumulative number is greater than a second cumulative number, determining that the audio packet forwarding direction is to forward to the first playback device, wherein the second cumulative number is the number of second historical audio packets in the second audio packet set; if the first cumulative number is less than or equal to the second cumulative number, determining that the audio packet forwarding direction is to forward to the second playback device.

[0007] In some embodiments, determining the audio packet forwarding direction identified by the current forwarding state flag comprises: in response to the first cumulative number being greater than or equal to the number threshold, determining that the audio packet forwarding direction is to the first playback device; and in response to the second cumulative number being greater than or equal to the number threshold, determining that the audio packet forwarding direction is to the second playback device.

[0008] In some embodiments, the method further comprises: sending the audio packet forwarding direction to the second playback device; or sending the second cumulative number to the second playback device to enable the second playback device to determine the audio packet forwarding direction.

[0009] In some embodiments, determining the audio packet forwarding direction identified by the current forwarding state flag comprises: sending the second cumulative number to the second playback device to enable the second playback device to determine the audio packet forwarding direction; and receiving the audio packet forwarding direction sent by the second playback device.

[0010] In some embodiments, before receiving the next Bluetooth downlink frame sent by the sound source device, sending at least one second historical audio packet in the second audio packet set to the second playback device based on the second audio packet set comprises: after a first time at which the Bluetooth downlink frame is received, sending the second historical audio packet to the second playback device based on the second audio packet set, wherein the frequency point at which the second playback device sends the second historical audio packet is different from the frequency point at which the sound source device sends the Bluetooth downlink frame; and before receiving the next Bluetooth downlink frame sent by the sound source device, attempting to receive at least one first historical audio packet in a first audio packet set sent by the second playback device based on the first audio packet set comprises: after a second time at which the Bluetooth downlink frame is received, attempting to receive the first historical audio packet sent by the second playback device based on the first audio packet set, wherein the frequency point at which the second playback device sends the first historical audio packet is different from the frequency point at which the sound source device sends the Bluetooth downlink frame.

[0011] In some embodiments, the first time and the second time are both later than the end time of the period occupied by the access code detection stage; or the first time and the second time are both later than the end time of the period occupied by the access code detection stage and the packet header detection stage.

[0012] In some embodiments, the method further comprises: receiving a second forwarding success notification sent by the second playback device, wherein the second forwarding success notification is sent by the second playback device in response to successfully receiving the second historical audio packet; and updating the second audio packet set based on the second forwarding success notification.

[0013] In some embodiments, the method further comprises: in response to successfully receiving the first historical audio package, sending a first forwarding success notification to the second playback device, so that the second playback device updates the first audio package set.

[0014] In some embodiments, the method further comprises: in response to all the detection stages detecting normal, obtaining the audio package.

[0015] In some embodiments, the method further comprises: sending a first confirmation signal to the sound source device; or, sending a receiving success signal to the second playback device, so that the second playback device sends the first confirmation signal to the sound source device.

[0016] In some embodiments, the method further comprises: in response to the audio package being correctly received, sending an audio package receiving success signal to the second playback device; determining a second receiving condition of the second playback device receiving the audio package, and in the second receiving condition representing that the second playback device fails to receive, updating the audio package to a second audio package set; sending a second confirmation signal to the sound source device, or sending the second confirmation signal to the sound source device through the second playback device, so that the sound source device transmits a next audio package through a next Bluetooth downlink frame.

[0017] In some embodiments, the method further comprises: in response to the audio package not being correctly received, sending an audio package negative acknowledgement signal to the second playback device or not sending an audio package receiving success signal to the second playback device, so that the second playback device updates the audio package to the first audio package set.

[0018] In a second aspect, the present disclosure provides a playback device, comprising: a Bluetooth module, configured to establish a first Bluetooth connection with a sound source device or to establish a second Bluetooth connection with another playback device in a truly wireless playback system by listening to a first Bluetooth connection established by the other playback device with the sound source device, receive a Bluetooth downlink frame sent by the sound source device, and when the audio packet forwarding direction is to forward to the other playback device, send at least one second historical audio packet in a second audio packet set to the other playback device before receiving a next Bluetooth downlink frame sent by the sound source device, or when the audio packet forwarding direction is to forward to the playback device, attempt to receive at least one first historical audio packet in a first audio packet set sent by the other playback device based on the first audio packet set before receiving the next Bluetooth downlink frame sent by the sound source device, wherein the Bluetooth downlink frame is used to transmit an audio packet, the second audio packet set is a second historical audio packet sequence that the other playback device fails to successfully receive from the sound source device, and the first audio packet set is a first historical audio packet sequence that the playback device fails to successfully receive from the sound source device; and a processing module, configured to sequentially pass the Bluetooth downlink frame through a plurality of detection stages for verification, stop continuing to detect the Bluetooth downlink frame, and determine an audio packet forwarding direction indicated by a current forwarding state flag in response to a Bluetooth access code detection failure, and / or a packet header detection failure, and / or a packet header field analysis determining that the Bluetooth downlink frame has no payload, wherein the plurality of detection stages comprise an access code detection stage and a packet header detection stage.

[0019] In a third aspect, the present disclosure provides a truly wireless playback device, comprising: two playback devices, wherein at least one playback device is configured to perform the audio transmission method provided in any one of the above aspects.

[0020] In a fourth aspect, the present disclosure provides an audio transmission system, comprising: a sound source device, configured to send a Bluetooth downlink frame used to transmit an audio packet; and a truly wireless playback device provided in any one of the above aspects, connected to the sound source device via Bluetooth, and configured to receive the audio packet.

[0021] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and are not limiting to the present disclosure.

[0022] The technical scheme provided by the embodiment of the present disclosure can have the following beneficial effects: according to the audio transmission method provided by the present disclosure, when the first playback device detects that the Bluetooth downlink frame is abnormal, the communication interaction between the first playback device and the audio source device can be temporarily interrupted, the audio packet transmission direction identified by the current forwarding state flag is determined, the audio packet transmission relationship between the first playback device and the second playback device is determined, and then the audio packet forwarding in the device is performed according to the audio packet transmission relationship in the idle time before receiving the next Bluetooth downlink frame sent by the audio source device, so as to complete the audio packets missing in the first playback device or the second playback device as much as possible, thereby helping to enhance the ability of the playback device to receive audio packets, guaranteeing the audio playback quality, thereby effectively reducing the transmission times between devices, saving the power consumption of the first playback device and the audio source device for audio transmission, effectively prolonging the use time of the first playback device, and improving the user experience. BRIEF DESCRIPTION OF DRAWINGS

[0023] The present disclosure can be better understood by describing exemplary embodiments thereof with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of an architecture of an audio transmission system according to an exemplary embodiment of the present disclosure; Figure 2 is a schematic diagram of an interaction timing of an audio transmission according to an exemplary embodiment of the present disclosure; Figure 3 is a flowchart of an audio transmission method according to an exemplary embodiment of the present disclosure; Figure 4 is a schematic diagram of a physical frame structure according to an exemplary embodiment of the present disclosure; Figure 5 is a schematic diagram of another physical frame structure according to an exemplary embodiment of the present disclosure; Figure 6 is a flowchart of another audio transmission method according to an exemplary embodiment of the present disclosure; Figure 7 is a schematic diagram of an interaction timing of another audio transmission according to an exemplary embodiment of the present disclosure; Figure 8 is a schematic diagram of a structure of a playback device according to an exemplary embodiment of the present disclosure; Figure 9 is a schematic diagram of an architecture of another audio transmission system according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] In the following detailed description of specific embodiments of the present disclosure, it is to be understood that the description is not meant to be as exhaustive as all of the features of an actual implementation can not be described for the sake of brevity. It should be realized that in the course of performing a typical engineering or design project, numerous implementation-specific decisions are made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which can vary from one implementation to another. Moreover, it should be appreciated that, while the development process can be complex and long, the end result can be a device, system, or method that is devised to achieve the developer's specific goals. Further, it should be understood that, while the application is described in connection with certain embodiments, it is not intended to be limited to the particular forms and examples disclosed. Instead, these descriptions are intended to cover all modifications and alternatives falling within the scope of the application.

[0025] Unless otherwise defined, technical terms or scientific terms used in the present disclosure shall have the ordinary meanings as understood by one of ordinary skill in the art to which the present disclosure pertains. The terms "first", "second", and similar terms are used herein to distinguish one element from another, but do not imply an order or sequence unless otherwise defined. The terms "one" and "a" and similar terms mean "at least one" and "one or more" unless otherwise defined. The terms "include" and "comprise" and similar terms are inclusive and open-ended and specify the presence of stated elements or integers or the presence of other elements or integers not expressly stated but inherent to such process, method, article, or apparatus. The terms "connected" and "coupled" and similar terms are not limited to direct or physical connections or couplings, but also include indirect or remote connections or couplings.

[0026] For the application scenario of audio playing through the true wireless playing device, two playing devices in the true wireless playing device can receive the audio packets sent by the audio source device through the Bluetooth downlink frame based on the Bluetooth connection between the audio source device and the two playing devices, and then perform audio playing. When the audio source device interacts with the two playing devices, it only needs to sense one of the playing devices and establish a Bluetooth connection with it, such as a classic Bluetooth connection or a low-power Bluetooth connection. The audio source device can be a smart phone, a pad, a notebook computer, various smart terminals, etc.

[0027] For example, taking the true wireless playing device as a true wireless earphone (TWS) as an example, the Bluetooth connection relationship between the true wireless earphone and the audio source device can be as shown in FIG. 1. Figure 1The true wireless earphone includes earphone 1 and earphone 2. Earphone 1 is configured to establish Bluetooth connection 1 with the audio source device, so as to communicate with the audio source device through Bluetooth. Earphone 1 and earphone 2 are connected with each other through Bluetooth connection 2. Via Bluetooth connection 2, earphone 1 can transmit the relevant parameters of Bluetooth connection 1 to earphone 2, so that earphone 2 listens to and receives the Bluetooth signal from the audio source device. The audio packets sent by the audio source device to earphone 1 and earphone 2 are carried in the Bluetooth downlink frame, that is, in the Bluetooth downlink frame belonging to Bluetooth connection 1 and the listening connection. Among them, the relevant information of Bluetooth connection 1 can include at least one of the clock of the Bluetooth piconet, the Bluetooth address of the audio source device, and the frequency hopping sequence of Bluetooth connection 1.

[0028] In terms of timing, Bluetooth connection 1 is composed of Bluetooth downlink frames and Bluetooth uplink frames alternately. Among them, the Bluetooth downlink frame is the Bluetooth frame synchronously sent by the audio source device to earphone 1 and earphone 2, and the Bluetooth uplink frame is the Bluetooth frame in which one of earphone 1 and earphone 2 feeds back the audio packet receiving situation to the audio source device, which can contain response information such as an acknowledgement signal or a negative acknowledgement signal. The interaction process can be as shown in the figure. Figure 2 Among them, Figure 2 Taking earphone 2 as the earphone that feeds back the audio packet receiving situation to the audio source device. In actual application, earphone 1 can also be the earphone that feeds back the audio packet receiving situation to the audio source device, which is not limited herein.

[0029] If earphone 1 correctly receives the Bluetooth downlink frame from the audio source device, it sends a receiving success signal representing the correct reception of earphone 1 to earphone 2 in the remaining time of the Bluetooth downlink frame time slot; if earphone 2 correctly receives the Bluetooth downlink frame from the audio source device or receives the receiving success signal from earphone 1, it sends an acknowledgement signal to the audio source device in the Bluetooth uplink frame. If the audio source device receives the acknowledgement signal, it can then send the next audio packet through the next Bluetooth downlink frame or a subsequent next Bluetooth downlink frame. If the audio source device does not receive the acknowledgement signal or receives a negative acknowledgement signal, it retransmits the audio packet through the next Bluetooth downlink frame until the feedback acknowledgement signal is received. Among them, for the audio packet transmitted by the audio source device through the Bluetooth downlink frame for the first time, the Bluetooth downlink frame can be referred to as the first frame, and for the audio packet transmitted by the audio source device repeatedly, the Bluetooth downlink frame can be referred to as the retransmission frame, and the retransmission number of the retransmission frame is greater than 1.

[0030] However, if the Bluetooth connection quality between the audio source device and the true wireless playback device is poor, it will cause the audio source device to retransmit the audio packet many times due to not receiving the acknowledgement signal, affecting the audio playback quality. Moreover, because the audio source device retransmits many times, it will also increase the number of communications between devices, increase the power consumption of the true wireless playback device, shorten the use time of the true wireless playback device, and affect the user's use experience.

[0031] Therefore, this disclosure provides an audio transmission method. This audio transmission method is applied to a first playback device in a true wireless playback device. The true wireless playback device may include, but is not limited to, true wireless earphones, true wireless stereo speakers, and other multi-device collaborative electronic devices consisting of at least two playback devices. The first playback device is connected to an audio source device via a first Bluetooth connection and to a second playback device in the true wireless playback device via a second Bluetooth connection. The first playback device can be any playback device in the true wireless playback device. The audio source device may be a smartphone, tablet, laptop, various smart terminals, etc. The connection relationship between the first playback device, the second playback device, and the audio source device can be as follows: Figure 1 As shown. In this embodiment of the disclosure, the first playback device and the second playback device can send an acknowledgment (ACK) signal to the audio source device if either playback device correctly receives the audio packet from the audio source device. In some embodiments, the first playback device can receive the audio packet by establishing a first Bluetooth connection with the audio source device. If the first playback device correctly receives the audio packet from the audio source device, it sends an acknowledgment signal to the audio source device; or, if the first playback device receives a reception success signal sent by the second playback device if it correctly receives the audio packet from the audio source device, the first playback device will send an acknowledgment signal to the audio source device even if it has not successfully received the audio packet. In other embodiments, the first playback device can also receive the audio packet by listening to the first Bluetooth connection established between the second playback device and the audio source device. In this embodiment, if the first playback device correctly receives the audio packet from the audio source device, it sends a reception success signal to the second playback device. Even if the second playback device has not successfully received the audio packet, it will still send an acknowledgment signal to the audio source device; correspondingly, the second playback device will also send an acknowledgment signal to the audio source device after correctly receiving the audio packet from the audio source device. The present invention enables more efficient acquisition of audio packets from audio source devices, reduces the frequency of retransmission of Bluetooth frames by audio source devices, improves transmission efficiency, and allows each playback device to acquire complete audio data through audio transmission between the first playback device and the second playback device.

[0032] like Figure 3 As shown, the audio transmission method provided in this disclosure may include the following steps: Step S210: Receive the Bluetooth downlink frame sent by the audio source device.

[0033] For scenarios involving audio playback via true wireless playback devices, the audio source device provides audio packets to the true wireless playback device, enabling it to play audio. Bluetooth downlink frames are used to transmit these audio packets.

[0034] Step S220: The Bluetooth downlink frames are verified through multiple detection stages in sequence.

[0035] To determine whether a received Bluetooth downlink frame is valid, it undergoes multiple detection stages for verification, with the determination based on the detection results. These stages include an access code detection stage and a header detection stage. The execution order of each detection stage corresponds to the arrangement order of the Bluetooth downlink frame fields and also corresponds one-to-one with multiple fields in the physical frame structure of the Bluetooth downlink frame.

[0036] The physical frame structure may differ for different Bluetooth data transfer rates. For example, Bluetooth data transfer rates can include a basic rate and an enhanced rate. For the basic rate, the physical frame structure of a Bluetooth downlink frame can be as follows: Figure 4 As shown. A Bluetooth physical frame includes three fields, arranged from least significant bit to most significant bit: Access Code 301, Header 302, and Payload 303. Access Code 301 is the identifier for the piconet, used for timing synchronization, offset compensation, paging, and querying; Header 302 contains information for Bluetooth link control; and Payload 303 carries valid information. For enhanced rates, the physical frame structure of a Bluetooth downlink frame can be as follows: Figure 5 As shown. A Bluetooth physical frame includes six fields, arranged from least significant bit to most significant bit: access code 304, header 305, guard interval 306, synchronization 307, enhanced rate payload 308, and trailer 309. Among these, access code 304, header 305, and enhanced rate payload 308 are... Figure 4 The access code 301, header 302, and payload 303 are similar and will not be described in detail here. Guard interval 306 indicates the interval between header 305 and synchronization 307; synchronization 307 contains a synchronization sequence, usually the synchronization sequence used by differential phase shift keying modulation; header 309 uses different settings for different modulation methods.

[0037] Specifically, the access code detection stage detects the access code in the audio downlink frame, the packet header detection stage detects the packet header in the audio downlink frame, and the packet header field parsing stage detects the control information carried in the packet header to determine whether a valid payload exists.

[0038] When verifying Bluetooth downlink frames, each detection stage can be performed sequentially according to the physical frame structure of the Bluetooth downlink frame. If the detection result of the current detection stage indicates success, the process proceeds to the next detection stage. For example, if the detection result of the access code detection stage of the Bluetooth downlink frame is successful, the header detection stage can be executed to determine the result. If the header detection result is normal, the header field parsing stage continues to determine if the payload exists. If the payload exists, the audio packet sent by the audio source device can be obtained through the payload. If the detection result of the current detection stage indicates failure, i.e., an anomaly, it can be assumed that the audio packet cannot be received correctly, and further detection can be stopped.

[0039] In some embodiments, the access code detection phase is mainly used to determine whether there is a Bluetooth downlink frame with a specified access code in the air interface, and to locate the frame start, correct symbol timing and frequency offsets, etc., for the reception of subsequent Bluetooth downlink frames. Access code detection failure means that the Bluetooth frame reception has failed. This could be due to the absence of a Bluetooth frame with the specified access code in the air interface, or the signal of the Bluetooth frame with the specified access code being too weak, having a poor signal-to-noise ratio, or being severely affected by airborne radio frequency interference.

[0040] The header detection phase primarily involves inspecting the header of the Bluetooth downlink frame. The header has a logical length of 18 bits; the air interface encoding can employ Forward Error Correction (FEC) with a coding rate of 1 / 3, consisting of repeated bits (each bit repeated 3 times, totaling 54 bits) to improve error resilience. The specific detection process may include counting the number of distinct 3-bit groups (up to 18 groups) within each group that are repeated 3 times (i.e., 3 bits that are neither "0 0 0" nor "1 1 1"). A large number of distinct bit groups indicates a low signal-to-noise ratio or significant interference in the header, resulting in erroneous bits in multiple groups. However, even with erroneous bits, the Bluetooth header verification is likely to succeed because each bit is repeated 3 times. If the header is successfully received, the parsing result of the corresponding field is considered successful. If the header is not successfully received, the parsing result of the corresponding field is considered unsuccessful. However, if the Bluetooth packet header reception fails, it could be due to a Header Error Check failure.

[0041] The header field parsing stage involves checking the internal control information of the header. Even if the Bluetooth header is successfully received (i.e., the header verification is successful), if the number of dissimilar bit groups is greater than or equal to a predetermined value, it indicates a low signal-to-noise ratio or significant interference in the received Bluetooth frame. In this case, even if the subsequent payload (including audio packet information) of the Bluetooth frame is received, it is difficult to receive it correctly, or the probability of correct reception is very low. Therefore, it can be assumed that the Bluetooth downlink frame does not contain a payload.

[0042] Step S230: Determine the forwarding direction of the audio packet indicated by the current forwarding status flag.

[0043] In response to an anomaly detected in the current detection phase of a Bluetooth downlink frame, indicating that the first playback device cannot correctly receive the Bluetooth downlink frame, the Bluetooth downlink frame may be invalid, and thus the detection of Bluetooth downlink frames can be stopped to avoid wasting resources. Therefore, there will be an idle period until the next Bluetooth downlink frame is received.

[0044] Therefore, to fully utilize this idle time, the forwarding direction of the audio packets identified by the current forwarding status flag is determined to ascertain the audio packet transmission and reception relationship between the first and second playback devices. Subsequently, this idle time can be used to achieve intra-device (between the first and second playback devices) audio packet forwarding, supplementing any missing audio packets from the history of either the first or second playback device, improving the audio packet reception success rate, ensuring audio playback quality, thereby reducing the number of transmissions between devices (between the audio source device and the true wireless playback device), saving power consumption during audio transmission with the audio source device, and extending usage time. Furthermore, transmitting historical audio packets during idle time ensures that the intra-device audio packet forwarding process does not affect various Bluetooth transmissions between the audio source device and the two playback devices during other time periods, guaranteeing the overall reliability and stability of audio packet data transmission. In this embodiment, the audio packet forwarding direction can initially be set to either forwarding to the second playback device or forwarding to the first playback device. Since it can be dynamically adjusted according to actual conditions during implementation, it can be set to either direction initially.

[0045] In step S240, if the audio packet forwarding direction is to the second playback device, then in response to the failure of Bluetooth downlink frame access code detection, and / or packet header detection failure, and / or packet header field parsing determining that the Bluetooth downlink frame has no payload, the detection of Bluetooth downlink frames is stopped, and before receiving the next Bluetooth downlink frame sent by the audio source device, at least one second historical audio packet in the second audio packet set is sent to the second playback device based on the second audio packet set.

[0046] If the audio packet forwarding direction is towards the second playback device, then the audio packet forwarding and receiving relationship within the devices is as follows: the first playback device acts as the sender, and the second playback device acts as the receiver. Therefore, before receiving the next Bluetooth downlink frame sent by the audio source device, the first playback device can temporarily interrupt its communication with the audio source device. It can then fully utilize this idle time to send at least one second historical audio packet from the second audio packet set to the second playback device. This allows the device to supplement any missing historical audio packets as much as possible through internal audio packet forwarding, enhancing its ability to receive audio packets and ensuring the audio playback quality. The second audio packet set is the sequence of second historical audio packets that the second playback device failed to receive from the audio source device, and the second historical audio packets are the audio packets that were previously missing from the second playback device. During a single transmission, the device can send one or more audio packets that were stored in the second audio packet set earliest, or it can send all audio packets in the second audio packet set together.

[0047] In step S250, if the audio packet forwarding direction is to the first playback device, then in response to the failure of Bluetooth downlink frame access code detection, and / or packet header detection failure, and / or packet header field parsing determining that the Bluetooth downlink frame has no payload, stop continuing to detect Bluetooth downlink frames, and before receiving the next Bluetooth downlink frame sent by the audio source device, attempt to receive the first historical audio packet sent by the second playback device based on the first audio packet set.

[0048] If the audio packet forwarding direction is towards the first playback device, then the audio packet forwarding and receiving relationship within the devices is as follows: the first playback device acts as the receiver, and the second playback device acts as the sender. Therefore, before receiving the next Bluetooth downlink frame sent by the audio source device, the first playback device can temporarily interrupt its communication with the audio source device. This allows it to fully utilize this idle time to attempt to receive at least one first historical audio packet from the first audio packet set sent by the second playback device based on the first audio packet set. This allows it to supplement any missing audio packets in the first playback device's history through internal audio packet forwarding, enhancing its ability to receive audio packets and ensuring the audio playback quality of the first playback device. Here, the first audio packet set is the sequence of first historical audio packets that the first playback device failed to receive from the audio source device, and the first historical audio packet is any missing audio packet in the first playback device's history. During a single transmission, one or more audio packets stored in the first audio packet set can be sent according to their order of inclusion in the first audio packet set, or all audio packets in the first audio packet set can be sent together.

[0049] According to the audio transmission method provided in this disclosure, when a first playback device detects an abnormal Bluetooth downlink frame, it can temporarily interrupt the communication interaction with the audio source device. Based on the audio packet forwarding direction indicated by the current forwarding status flag, it determines the audio packet transmission and reception relationship between the first playback device and the second playback device. Then, using the idle time before receiving the next Bluetooth downlink frame sent by the audio source device, it forwards audio packets within the device according to the audio packet transmission and reception relationship, so as to make up for the audio packets that were missing in the history of the first playback device or the second playback device as much as possible. This helps to enhance the playback device's ability to receive audio packets, ensure audio playback quality, effectively reduce the number of transmissions between devices, save power consumption during audio transmission between the first playback device and the audio source device, effectively extend the usage time of the first playback device, and improve the user experience.

[0050] In some embodiments, the protocol used for audio packet forwarding within the device may include, but is not limited to: Bluetooth protocol, Bluetooth HDT (High Data Throughput) protocol, modified Bluetooth protocol, or other wireless transmission protocols, and proprietary wireless transmission protocols. For example, the payload of the forwarded audio packet may use a modulation order higher than that of the Bluetooth downlink frame, such as QAM16 or QAM64; the physical frame of the forwarded historical audio packet may use a higher symbol rate, such as 2M symbols / s, 3M symbols / s, or 4M symbols / s. This allows for full reuse of existing Bluetooth modules, increases the transmission rate of forwarded audio packets, improves the reliability of forwarded historical audio packet transmission, and reduces the time spent on forwarding audio packets. This enables the transmission of forwarded audio packets to be completed within the idle time after the Bluetooth downlink frame is received or before the next Bluetooth downlink frame is sent by the receiving audio source device.

[0051] The following will explain in detail the process of determining the forwarding direction of the audio packet indicated by the current forwarding status flag.

[0052] In some embodiments, the process of determining the audio packet forwarding direction may include the following steps: Step a1: Receive the first cumulative count sent by the second playback device; Step a2: If the first cumulative number is greater than the second cumulative number, then the audio packet forwarding direction is determined to be forwarded to the first playback device; Step a3: If the first cumulative quantity is less than or equal to the second cumulative quantity, then the audio packet forwarding direction is determined to be forwarded to the second playback device.

[0053] The first cumulative quantity is the number of the first historical audio packets in the first audio packet set, and the second cumulative quantity is the number of the second historical audio packets in the second audio packet set.

[0054] Specifically, when a playback device is missing too many historical audio packets, it will affect the audio playback quality, causing issues such as interruptions, stuttering, and noise. Furthermore, during actual synchronous audio transmission, for the same Bluetooth downlink frame, the first playback device will interact with the second playback device to monitor the reception of the transmitted audio packets. Therefore, the two playback devices can determine whether the other is missing a particular audio packet based on the reception status of the other's audio packets. If it is determined that the other party is missing an audio packet, it will be included as a missing historical audio packet and added to the corresponding audio packet set for targeted transmission later through the device's internal audio packet forwarding mechanism.

[0055] To ensure the effectiveness of audio transmission, the forwarding direction of the audio packet is indicated by the current forwarding status flag, so that the first playback device and the second playback device transmit audio packets in a unidirectional manner. This helps to enhance transmission stability, reduce the probability of air interface collisions, reduce transmission latency, and improve the transmission efficiency of audio packets.

[0056] Since the missing audio packets in the first playback device are statistically analyzed by the second playback device, to determine the audio packet forwarding direction, the first cumulative count sent by the second playback device is received to clarify the missing audio packets in the first playback device. Furthermore, the first playback device also continuously analyzes the missing audio packets in the second playback device's history, thus directly determining the second cumulative count of the second historical audio packets. A larger cumulative count indicates that the corresponding playback device is more likely to experience audio playback quality issues. Therefore, to ensure the performance of the playback devices, the first and second cumulative counts are compared to identify the playback devices more prone to audio playback quality problems. If the first cumulative count is greater than the second cumulative count, it indicates that the first playback device is more likely to experience audio playback quality problems than the second playback device. Therefore, the audio packet forwarding direction is determined to be forwarded to the first playback device. This in-device audio packet forwarding method aims to supplement the missing first historical audio packets of the first playback device as much as possible, ensuring the integrity of the first playback device's audio packet reception, improving the first playback device's audio packet reception capability, and guaranteeing the audio playback quality of the first playback device. If the first cumulative number is less than or equal to the second cumulative number, it indicates that the second playback device is more prone to audio playback quality problems than the first playback device. Therefore, the audio packet forwarding direction is determined to be forwarded to the second playback device. In order to supplement the second historical audio packets missing by the second playback device as much as possible through the audio packet forwarding method within the device, so as to ensure the integrity of the audio packet reception of the second playback device, improve the audio packet reception capability of the second playback device, and ensure the audio playback quality of the second playback device.

[0057] In other embodiments, the process of determining the audio packet forwarding direction may further include the following steps: Step a4: In response to the first cumulative number being greater than or equal to the number threshold, the forwarding direction of the audio packet is determined to be forwarding to the first playback device; Step a5: In response to the second cumulative quantity being greater than or equal to the quantity threshold, the audio packet forwarding direction is determined to be forwarded to the second playback device.

[0058] Specifically, when too many audio packets are missing, it will affect the smoothness of audio playback. Therefore, to ensure audio playback quality, a maximum number of audio packets that can be missing is predefined, i.e., a quantity threshold. For example, this quantity threshold can be 30, meaning that the maximum number of audio packets that can be missing is 30. The quantity threshold can be dynamically adjusted based on communication parameters such as Bluetooth channel quality and audio sampling rate, and is not limited here.

[0059] In response to the first cumulative number being greater than or equal to the number threshold, which represents the number of historical audio packets missing by the first playback device, the audio packet forwarding direction is determined to be forwarded to the first playback device, so as to make up for the missing first historical audio packets as much as possible through the second playback device and ensure audio playback quality.

[0060] In response to the second cumulative quantity being greater than or equal to the quantity threshold, which represents the number of historical audio packets missing by the second playback device, the audio packet forwarding direction is determined to be forwarded to the second playback device, so as to make up for the missing second historical audio packets as much as possible through the first playback device and ensure audio playback quality.

[0061] In some examples, the audio transmission method provided in this disclosure can also send the audio packet forwarding direction to a second playback device. The first playback device is the entity responsible for determining the audio packet forwarding direction. To enable the second playback device to clearly understand the audio packet forwarding direction within its device, the determined audio packet forwarding direction is sent to the second playback device, allowing the two playback devices to synchronize the audio packet forwarding direction, ensuring the unidirectionality of audio packet forwarding, and thus contributing to the effectiveness and stability of audio packet data transmission.

[0062] In other examples, the audio transmission method provided in this disclosure may also send a second cumulative quantity to a second playback device so that the second playback device determines the direction of audio packet forwarding.

[0063] In one scenario, both the first and second playback devices are entities responsible for determining the audio packet forwarding direction. Therefore, to enable the second playback device to clearly define the audio packet forwarding direction within its device, a second cumulative quantity is sent to the second playback device. This allows the second playback device to determine the audio packet forwarding direction by executing steps a1-a5 above. Consequently, when forwarding audio packets within the device, both playback devices can transmit in the same direction, ensuring the unidirectionality of audio packet forwarding. This helps guarantee the orderliness and stability of audio transmission and improves the transmission efficiency of audio packets.

[0064] In some other embodiments, the process of determining the audio packet forwarding direction may include the following steps: Step b1: Send the second cumulative quantity to the second playback device so that the second playback device can determine the audio packet forwarding direction; Step b2: Receive the audio packet forwarding direction sent by the second playback device.

[0065] Specifically, when the first playback device is not the entity responsible for determining the audio packet forwarding direction, but the second playback device is, the first playback device itself lacks the capability to determine the audio packet forwarding direction. Therefore, to enable the first playback device to clearly define the audio forwarding direction, it sends a second cumulative quantity to the second playback device. This allows the second playback device to determine the audio packet forwarding direction by executing steps a1-a5 and simultaneously inform the first playback device. This enables the first playback device to forward audio packets within its device based on the forwarding direction, ensuring the unidirectionality of audio packet forwarding. This, in turn, helps guarantee the orderliness and stability of audio transmission and improves audio packet transmission efficiency.

[0066] In some embodiments, step S230 may include: sending a second historical audio packet to a second playback device based on a second audio packet set after the first moment when the Bluetooth downlink frame is received. There is a certain duration between the receipt of the Bluetooth downlink frame and the receipt of the next Bluetooth downlink frame. To avoid affecting the normal reception of Bluetooth downlink frames by the second playback device, when the audio forwarding direction is determined to be forwarding to the second audio device, the second historical audio packet is sent to the second playback device based on the second audio packet set after the first moment when the Bluetooth downlink frame is received. This attempts to allow the second playback device to receive the second historical audio packet before it receives the next Bluetooth downlink frame, thereby enhancing the audio packet reception capability of the second playback device and ensuring the integrity of the audio packet reception. The first moment can be understood as the starting moment that triggers the sending of the second historical audio packet to the second playback device. The frequency point at which the first playback device sends the second historical audio packet is different from the frequency point at which the audio source device sends the Bluetooth downlink frame, thus helping to avoid interference from the Bluetooth downlink frame sent by the audio source device with the internal audio packet forwarding of the device.

[0067] In some examples, when sending the second historical audio packet to the second playback device, the second historical audio packet can be sent one by one according to the second audio packet set, and the next second historical audio packet can be sent only after it is confirmed that the second historical audio packet has been successfully received, so as to ensure the transmission quality of the second historical audio packet.

[0068] In other examples, when sending the second historical audio packets to the second playback device, they can be sent in batches according to the second audio packet set, so that the second playback device can receive as many second historical audio packets as possible during the idle time. This allows the second playback device to quickly supplement the missing second historical audio packets in a short period of time, thereby helping to improve the efficiency of audio packet forwarding within the device and improving the reception efficiency of the second playback device in receiving the second historical audio packets.

[0069] In other embodiments, if the second playback device determines that the audio forwarding direction is to the second audio device, after the third moment when the Bluetooth downlink frame is received, it may attempt to receive the second historical audio packet sent by the first playback device based on the second audio packet set, so as to make up for the second historical audio packet it is missing as much as possible, enhance its own audio packet receiving capability, thereby ensuring the integrity of audio packet reception and improving the success rate of audio packet reception.

[0070] The third time point can start at the same time as the first time point, which helps avoid missing the reception of second historical audio packets and improves the success rate of audio packet forwarding within the device. The third time point can also be later than the first time point, ensuring that the second audio device can directly receive the second historical audio packets transmitted by the first playback device, thus reducing reception latency and improving the second audio device's audio packet reception capability. Alternatively, the third time point can be earlier than the first time point, allowing for timely reception of the second historical audio packets sent by the first audio device, thereby increasing the number of second historical audio packets transmitted in a single transmission and improving completion efficiency. The time order between the third and first times points can be configured as needed and is not limited here.

[0071] In some embodiments, step S240 may include: after a second moment when a Bluetooth downlink frame is received, attempting to receive a first historical audio packet sent by the second playback device based on a first audio packet set. The second moment can be understood as the start moment that triggers the reception of the first historical audio packet sent by the second playback device. The frequency at which the second playback device sends the first historical audio packet is different from the frequency at which the audio source device sends the Bluetooth downlink frame, thereby helping to avoid interference from the Bluetooth downlink frame sent by the audio source device with the internal audio packet forwarding of the device.

[0072] Since the first playback device can determine that the second playback device will need to send the first historical audio packet to it by determining the audio forwarding direction, in order to avoid missing reception, after receiving the second moment of the Bluetooth downlink frame, it attempts to receive the first historical audio packet sent by the second playback device based on the first audio packet set, so as to make up for the missing first historical audio packet as much as possible, enhance its own audio packet reception capability, ensure the integrity of audio packet reception, and improve the success rate of audio packet reception.

[0073] In other embodiments, the second playback device may send a first historical audio packet to the first playback device based on the first audio packet set after the fourth moment when the Bluetooth downlink frame is received, in order to attempt to allow the first playback device to receive the first historical audio packet before the first playback device receives the next Bluetooth downlink frame, thereby enhancing the audio packet receiving capability of the first playback device and ensuring the integrity of the audio packet reception.

[0074] In some examples, when sending the first historical audio packet to the first playback device, the first historical audio packet can be sent one by one according to the first audio packet set, and the next first historical audio packet can be sent only after it is confirmed that the first historical audio packet has been successfully received, so as to ensure the transmission quality of the first historical audio packet.

[0075] In other examples, when sending the first historical audio packets to the first playback device, they can be sent in batches according to the first audio packet set, so that the first playback device can receive as many first historical audio packets as possible during the idle time. This allows the first playback device to quickly supplement the missing first historical audio packets in a short time, thereby helping to improve the efficiency of audio packet forwarding within the device and improve the reception efficiency of the first playback device in receiving the second historical audio packets.

[0076] The fourth time point can start at the same time as the second time point, which helps avoid missing the reception of the first historical audio packet and improves the success rate of audio packet forwarding within the device. The fourth time point can also be later than the second time point, ensuring that the first audio device can directly receive the first historical audio packet transmitted by the second playback device, if it is allowed to receive the first historical audio packet sent by the second playback device, thus reducing the reception latency of the first audio packet and improving the first audio device's audio packet reception capability. The fourth time point can also be earlier than the second time point, allowing for timely reception of the first historical audio packet sent by the second audio device, thus increasing the number of first historical audio packets transmitted in a single transmission and improving completion efficiency. The time order between the fourth and second times point can be configured according to requirements and is not limited here.

[0077] In some embodiments, both the first and second moments are later than the end of the access code detection phase, thereby ensuring that the audio packet forwarding process within the device does not affect the normal reception of Bluetooth downlink frames sent by the audio source device by the first and second playback devices. This ensures that frame transmission between devices and audio packet forwarding within the device can proceed in an orderly manner, avoiding air interface conflicts. For example, if the access code detection phase in the Bluetooth downlink frame occupies 72μs, the first and second moments can be configured to be later than 72μs and before receiving the next Bluetooth downlink frame, ensuring that at least one historical audio packet can be completely transmitted.

[0078] In other embodiments, both the first and second moments are later than the end of the time periods occupied by the access code detection phase and the header detection phase, which helps to reduce invalid forwarding and ensure the success rate of audio packet forwarding within the device. For example, if the time periods occupied by the access code detection phase and the header detection phase in a Bluetooth downlink frame are 72μs and 54μs respectively, then when configuring the first and second moments, they can be configured to be later than 126μs and before receiving the next Bluetooth downlink frame, ensuring that at least one historical audio packet can be completely transmitted.

[0079] In other embodiments, the first, second, third, and fourth moments are all later than the end of the time period occupied by the Bluetooth synchronization code, or they are all later than the end of the time period occupied by the access code detection phase and the packet header detection phase, so that both the first and second playback devices can receive Bluetooth downlink frames normally, thereby enabling audio packet forwarding within the device without affecting the correct reception of audio packets, and improving the success rate of the playback device receiving audio packets.

[0080] In some other embodiments, the first, second, third, and fourth moments can all be earlier than the end time of the access code detection phase plus a fixed time period, such as 80μs. This time period can be used for frequency switching, preparation for sending historical audio packets, etc.

[0081] In some embodiments, the Bluetooth downlink frame includes at least one time slot to regulate the communication timing between the audio source device and the true wireless playback device, avoid channel conflicts, and improve transmission efficiency. The number of time slots can be determined based on the Bluetooth protocol version (such as Bluetooth Classic BR / EDR or Bluetooth Low Energy BLE) and frame type; for example, it can include one, three, or five time slots. The time slot length can be determined based on a Time Division Multiple Access (TDMA) mechanism, dividing the time of the Bluetooth communication channel between the true wireless playback device and the audio source device; for example, the duration of one time slot can be 625µs. Because the duration of a single time slot is sufficient for the playback device to complete the detection of Bluetooth downlink frames, in order to improve forwarding efficiency and simplify forwarding control, the first, second, third, and fourth times can all be configured after the start time of the specified time slot. This not only ensures that the playback device receives audio packets through Bluetooth downlink frames, but also allows for audio packet forwarding within the remaining time of the specified time slot. This effectively improves the utilization rate of the time slot, thereby greatly enhancing the ability of the two playback devices to receive audio packets. This results in smooth audio signals, such as music, sent from the source device to the two playback devices, without interruption or stuttering. It also effectively reduces the number of times the two playback devices receive retransmitted audio packets from the source device, thus reducing the power consumption of the two playback devices.

[0082] In some embodiments, such as Figure 6 As shown, the audio transmission method may further include the following steps: Step S260: Receive the second forwarding success notification sent by the second playback device.

[0083] The second forwarding success notification is sent by the second playback device in response to successfully receiving the second historical audio packet. That is, after successfully receiving the second historical audio packet, the second playback device can send a second forwarding success notification to the first playback device to inform it that the second historical audio packet has been successfully received and is no longer the missing audio packet for the second playback device.

[0084] Step S270: Update the second audio packet set based on the second forwarding success notification.

[0085] Upon receiving the second successful forwarding notification, the successfully received second historical audio packets are removed from the second audio packet set to prevent subsequent duplicate transmissions and ensure the success rate of audio packet reception on the second playback device, thereby obtaining an updated second audio packet set. By updating the second audio packet set in real time, missing historical audio packets from the second earphone can be synchronized with the second audio packet set stored on the first playback device, ensuring consistency of missing records between the two playback devices and avoiding duplicate or missed transmissions.

[0086] In other embodiments, such as Figure 6 As shown, the audio transmission method may further include the following steps: In step S280, in response to successfully receiving the first historical audio packet, a first forwarding success notification is sent to the second playback device so that the second playback device updates the first audio packet set.

[0087] Upon successful reception of the first historical audio packet, indicating that the first playback device is no longer missing the first historical audio packet, a first forwarding success notification is sent to the second playback device. This allows the second playback device to remove the successfully received first historical audio packet from the first audio packet set based on the received notification, preventing subsequent duplicate transmissions and ensuring the first playback device's audio packet reception success rate, thus obtaining an updated first audio packet set. By updating the first audio packet set in real time, the missing historical audio packets from the first earphone can be synchronized with the first audio packet set stored in the second playback device, ensuring consistency of missing records between the two playback devices and preventing duplicate or missed transmissions.

[0088] In some embodiments, the audio transmission method may further include: in response to multiple detection stages all being detected as normal, acquiring an audio packet to ensure complete reception of the audio packet.

[0089] In other embodiments, during actual device-to-device interaction, when the audio source device transmits audio to the true wireless playback device, it interacts directly with the master device within the true wireless playback device. The master device can determine whether the audio packet has been correctly received. Therefore, when the first playback device is the master device, it can send a first acknowledgment signal to the audio source device to inform it that the audio packet has been successfully received. Then, when the audio source device sends the next Bluetooth downlink frame, it can transmit the next audio packet through the next Bluetooth downlink frame, ensuring the continuity of audio packet transmission. When the second playback device is the master device, the first playback device can send a successful reception signal to the second playback device, causing the second playback device to send a first acknowledgment signal to the audio source device. Then, when the audio source device sends the next Bluetooth downlink frame, it can transmit the next audio packet through the next Bluetooth downlink frame, ensuring the continuity of audio packet transmission.

[0090] In some embodiments, the audio transmission method may further include the following steps: Step c1: In response to the audio packet being correctly received, send an audio packet reception success signal to the second playback device; Step c2: Determine the second reception status of the audio packet received by the second playback device. If the second reception status indicates that the second playback device has failed to receive the audio packet, then update the audio packet to the second audio packet set. Step c3: Send a second confirmation signal to the audio source device, or send a second confirmation signal to the audio source device through the second playback device, so that the audio source device can transmit the next audio packet through the next Bluetooth downlink frame.

[0091] Specifically, if the first playback device can receive the audio packet correctly, it sends an audio packet reception success signal to the second playback device to inform the second playback device that it can successfully receive the first audio packet sent through the first Bluetooth frame. Therefore, regardless of whether the second playback device can successfully receive the first audio packet in the future, it does not need to update the first audio packet set.

[0092] By determining the second reception status of the initial audio packet received by the second playback device, it can be determined whether the second playback device successfully received the initial audio packet. This second reception status can be initiated by the second playback device or determined by the failure to receive feedback within a pre-agreed time interval. The second reception status indicates whether the second playback device successfully received the initial audio packet or not. However, if no feedback is received within the pre-agreed time interval, it can be directly determined that the second playback device failed to receive the initial audio packet.

[0093] If the second reception condition indicates that the second playback device has failed to receive the audio packet, the first audio packet can be used as the second historical audio packet and added to the second audio packet set for updating. Then, the first audio device can follow the updated second audio packet set so that the missing first audio packet of the second playback device can be synchronized with the second audio packet set stored in the first playback device. This can ensure the consistency of missing records between the two playback devices and avoid duplicate or missed transmissions.

[0094] Once the first playback device successfully receives the first audio packet, it can send a second confirmation signal to the audio source device, or the second playback device can send a second confirmation signal to the audio source device, so that the audio source device can transmit the next audio packet through the next Bluetooth downlink frame. This eliminates the need to retransmit the first audio packet, thereby greatly reducing the number of times the audio source device retransmits the audio packet and saving power consumption caused by inter-device transmission in true wireless playback devices, thus effectively extending the usage time.

[0095] According to the audio transmission method provided in this disclosure, for the first Bluetooth frame, as long as the first playback device can successfully receive it, it can send a second confirmation signal to the audio source device so that the audio source device can transmit the next audio packet through the next Bluetooth downlink frame. Subsequently, the historical audio packets can be supplemented by transmitting the Bluetooth downlink frames within the device. In the case of unlimited air resources but limited resources, the number of times the audio source device retransmits audio packets can be greatly reduced, saving the power consumption of the true wireless playback device caused by inter-device transmission, thereby effectively extending the usage time.

[0096] In some embodiments, the audio transmission method may further include: in response to an audio packet not being correctly received, sending an audio packet negative acknowledgment signal to a second playback device or not sending an audio packet reception success signal to the second playback device, so that the second playback device updates the audio packet to the first audio packet set. This enables the second playback device to update the missing audio packet in the first audio packet set stored in the second playback device based on the negative acknowledgment signal or the absence of a reception success signal, thereby helping to ensure the consistency of missing records between the two playback devices and avoiding duplicate or missed transmissions.

[0097] In some optional application scenarios, taking true wireless playback devices as true wireless earbuds as an example, combined with Figure 1The connection shown illustrates the audio transmission process between the audio source device and the two earbuds (earbud 1 and earbud 2) in the true wireless earbuds, as follows. Each earbud has a Bluetooth module. The first Bluetooth connection between either earbud and the audio source device, and the second Bluetooth connection with the other earbud, are both achieved through time-division multiplexing of their internal Bluetooth modules. Missing packet information can be transmitted between earbuds 1 and 2 via the second Bluetooth connection, or via other private wireless connections between them.

[0098] When earphone 2 successfully forwards the first historical audio packet to earphone 1, the first historical audio packet is removed from the first audio packet set stored in earphone 2. When earphone 1 successfully forwards the second historical audio packet to earphone 2, the second historical audio packet is removed from the second audio packet set stored in earphone 1.

[0099] like Figure 7 As shown, the audio source device sends a retransmitted Bluetooth frame ( Figure 7 The TX0 of the mid-range audio source device). Earphone 2 detects received retransmitted Bluetooth frames ( Figure 7 (RX0 of earphone 2) When earphone 2 fails to detect the Bluetooth access code, fails to receive the Bluetooth packet header, or earphone B detects in the packet header that the Bluetooth downlink frame does not contain a payload and the audio packet forwarding direction is to earphone 1, then after the first time T1 after the start time of the specified time slot of the Bluetooth downlink frame, the historical audio packet missing by earphone 1 is forwarded to earphone 1. Figure 7 Relay_TX0 of the middle earphone 2).

[0100] If the Bluetooth access code detection of earphone 1 fails, or the Bluetooth packet header reception fails, or if earphone A detects in the packet header that the Bluetooth downlink frame does not contain a payload and the audio packet forwarding direction is to earphone 1, then after the third time T3 after the start time of the Bluetooth downlink frame slot, the historical audio packet missing from earphone 1 is received from earphone 2. Figure 7 (Relay_RX0 of headphone 1).

[0101] In some embodiments, if earphone 1 correctly receives the forwarded historical audio packets, it sends a forwarding success notification to earphone 2; if it fails to receive the forwarded historical audio packets, it sends a forwarding failure notification to earphone 2 or does not send any feedback. This allows earphone 2 to clearly understand the reception status of the forwarded historical audio packets by earphone 1, facilitating timely updates to the corresponding audio packet set of earphone 1, ensuring consistency of missing records between the two earphones, and avoiding duplicate or missed transmissions. Figure 7 The diagram only shows the timing sequence of earphone 2 forwarding historical audio packets to earphone 1. The timing sequence of earphone 1 forwarding historical audio packets to earphone 2 is similar to that of earphone 2 forwarding historical audio packets to earphone 1, and will not be described again here.

[0102] In other embodiments, if at least one of earphones 2 and 1 successfully receives an audio packet transmitted via Bluetooth downlink frames, a first acknowledgment signal is sent to the audio source device via the main earphone. The main earphone can be either earphone 2 or earphone 1.

[0103] Based on the same inventive concept, this disclosure also provides a playback device. For example... Figure 8 As shown, the playback device 400 may include: Bluetooth module 410 is used to establish a first Bluetooth connection with an audio source device or to establish a second Bluetooth connection with another playback device by listening to the first Bluetooth connection established between another playback device and the audio source device in a true wireless playback device, and to receive Bluetooth downlink frames sent by the audio source device. When the audio packet forwarding direction is to forward to another playback device, before receiving the next Bluetooth downlink frame sent by the audio source device, it sends at least one second historical audio packet in the second audio packet set to another playback device based on the second audio packet set. Alternatively, when the audio packet forwarding direction is to forward to the playback device, before receiving the next Bluetooth downlink frame sent by the audio source device, it attempts to receive at least one first historical audio packet in the first audio packet set sent by another playback device based on the first audio packet set. The Bluetooth downlink frame is used to transmit audio packets, the second audio packet set is the sequence of second historical audio packets that the other playback device has not successfully received from the audio source device, and the first audio packet set is the sequence of first historical audio packets that the playback device has not successfully received from the audio source device. The processing module 420 is used to verify the Bluetooth downlink frame through multiple detection stages in sequence. In response to the failure of Bluetooth downlink frame access code detection, and / or packet header detection failure, and / or packet header field parsing determining that the Bluetooth downlink frame has no payload, the module stops further detection of the Bluetooth downlink frame and determines the forwarding direction of the audio packet identified by the current forwarding status flag. The multiple detection stages include: access code detection stage and packet header detection stage.

[0104] In some embodiments, the playback device has only one Bluetooth module, which can be a standard Bluetooth module connected to the audio source device, thus adapting to various audio source devices; the Bluetooth module (such as Bluetooth HDT, an improved Bluetooth protocol) or wireless module that forwards audio packets between the two playback devices, at least partially reusing the standard Bluetooth module. Only one Bluetooth module operates at a time, which helps reduce the cost of the playback device.

[0105] Regarding the playback device in the above embodiments, the specific methods by which each module performs its operations have been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0106] Based on the same inventive concept, this disclosure also provides a true wireless playback device. This true wireless playback device may include two playback devices, wherein at least one playback device is used to execute any of the audio transmission methods provided in this disclosure, thereby effectively improving the success rate of audio packet reception, ensuring audio playback quality, and, based on the internal audio packet forwarding of the true wireless playback device, significantly reducing the number of communication operations between devices, thus helping to reduce the power consumption of the true wireless playback device and extend its usage time.

[0107] Based on the same inventive concept, this disclosure also provides an audio transmission system. For example... Figure 9 As shown, the audio transmission system 500 may include: Audio source device 510 is used to send Bluetooth downlink frames, which are used to transmit audio packets. The true wireless playback device 520 is connected to the audio source device 510 via Bluetooth for receiving audio packets. The true wireless playback device 520 can be any type of true wireless playback device provided in this disclosure.

[0108] This disclosure uses specific terms to describe embodiments of the present disclosure. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the present disclosure. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the present disclosure can be appropriately combined.

[0109] In the context of this disclosure, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0110] Similarly, it should be noted that, in order to simplify the description of this disclosure and thus aid in the understanding of one or more embodiments, the foregoing description of embodiments of this disclosure may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of this disclosure requires more features than the features claimed. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0111] The basic concepts have been described above. It is obvious that the above disclosure is merely illustrative and does not constitute a limitation of this disclosure. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this disclosure by those skilled in the art. Such modifications, improvements, and corrections are suggested in this disclosure and therefore remain within the spirit and scope of the embodiments of this disclosure.

Claims

1. An audio transmission method applied to a first playback device in a true wireless playback system, the first playback device being connected with a second playback device in the true wireless playback system through a second Bluetooth connection, and receiving an audio packet through a first Bluetooth connection established with an audio source device or through listening to a first Bluetooth connection established by the second playback device with the audio source device; the audio transmission method comprising: receiving a Bluetooth downlink frame sent by the audio source device, wherein the Bluetooth downlink frame is used to transmit an audio packet; sequentially verifying the Bluetooth downlink frame through a plurality of detection stages, wherein the plurality of detection stages comprise an access code detection stage and a packet header detection stage; determining an audio packet forwarding direction identified by a current forwarding state flag; if the audio packet forwarding direction is to forward to the second playback device, in response to the Bluetooth downlink frame access code detection failure, and / or packet header detection failure, and / or packet header field analysis determining that the Bluetooth downlink frame has no payload, stopping to continue detecting the Bluetooth downlink frame, and before receiving a next Bluetooth downlink frame sent by the audio source device, sending at least one second historical audio packet in a second audio packet set to the second playback device based on the second audio packet set, wherein the second audio packet set is a second historical audio packet sequence that the second playback device has not successfully received from the audio source device; if the audio packet forwarding direction is to forward to the first playback device, in response to the Bluetooth downlink frame access code detection failure, and / or packet header detection failure, and / or packet header field analysis determining that the Bluetooth downlink frame has no payload, stopping to continue detecting the Bluetooth downlink frame, and before receiving the next Bluetooth downlink frame sent by the audio source device, attempting to receive at least one first historical audio packet in a first audio packet set sent by the second playback device based on the first audio packet set, wherein the first audio packet set is a first historical audio packet sequence that the first playback device has not successfully received from the audio source device.

2. The audio transmission method of claim 1, wherein, The determination of the audio packet forwarding direction identified by the current forwarding state flag comprises: receiving a first cumulative number sent by the second playback device, wherein the first cumulative number is a number of the first historical audio packets in the first audio packet set; if the first cumulative number is greater than a second cumulative number, determining that the audio packet forwarding direction is to forward to the first playback device, wherein the second cumulative number is a number of the second historical audio packets in the second audio packet set; if the first cumulative number is less than or equal to the second cumulative number, determining that the audio packet forwarding direction is to forward to the second playback device.

3. The audio transmission method of claim 1, wherein, The determination of the audio packet forwarding direction identified by the current forwarding state flag comprises: in response to the first cumulative number being greater than or equal to a number threshold, determining that the audio packet forwarding direction is to forward to the first playback device, wherein the first cumulative number is a number of the first historical audio packets in the first audio packet set; In response to the second cumulative number being greater than or equal to the number threshold, it is determined that the audio packet forwarding direction is to forward to the second playback device, wherein the second cumulative number is a number of the second historical audio packets in the second audio packet set.

4. The audio transmission method according to claim 2 or 3, wherein, The method further comprises: sending the audio packet forwarding direction to the second playback device; or, sending the second cumulative number to the second playback device to enable the second playback device to determine the audio packet forwarding direction.

5. The audio transmission method of claim 1, wherein, The determination of the audio packet forwarding direction identified by the current forwarding state flag comprises: sending the second cumulative number to the second playback device to enable the second playback device to determine the audio packet forwarding direction; receiving the audio packet forwarding direction sent by the second playback device.

6. The audio transmission method of claim 1, wherein, the sending of the at least one second historical audio packet in the second audio packet set to the second playback device based on the second audio packet set before the receiving of the next Bluetooth downlink frame sent by the sound source device comprises: after a first time point at which the Bluetooth downlink frame is received, sending a second historical audio packet to the second playback device based on a second audio packet set, wherein a frequency point at which the second playback device sends the second historical audio packet is different from a frequency point at which the sound source device sends the Bluetooth downlink frame; the attempting to receive the at least one first historical audio packet in the first audio packet set sent by the second playback device based on the first audio packet set before the receiving of the next Bluetooth downlink frame sent by the sound source device comprises: after a second time point at which the Bluetooth downlink frame is received, attempting to receive a first historical audio packet sent by the second playback device based on a first audio packet set, wherein a frequency point at which the second playback device sends the first historical audio packet is different from a frequency point at which the sound source device sends the Bluetooth downlink frame.

7. The audio transmission method of claim 6, wherein, the first time point and the second time point are both later than a termination time point of a time period occupied by the access code detection stage; or the first time point and the second time point are both later than a termination time point of a time period occupied by the access code detection stage and the packet header detection stage.

8. The audio transmission method of claim 1, wherein, The method further comprises: receiving a second forwarding success notification sent by the second playback device, wherein the second forwarding success notification is sent by the second playback device in response to a successful reception of the second historical audio packet; updating the second audio packet set based on the second forwarding success notification.

9. The audio transmission method of claim 1, wherein, The method further comprises: in response to a successful reception of the first historical audio packet, sending a first forwarding success notification to the second playback device to enable the second playback device to update the first audio packet set.

10. The audio transmission method of claim 1, wherein, The method further comprises: in response to all of the plurality of detection stages detecting normally, obtaining the audio packet.

11. The audio transmission method of claim 10, wherein, The method further comprises: sending a first confirmation signal to the sound source device; or, sending a reception success signal to the second playback device to enable the second playback device to send the first confirmation signal to the sound source device.

12. The audio transmission method of claim 10, wherein, The method further comprises: sending an audio packet reception success signal to the second playback device in response to the audio packet being correctly received; determining a second reception condition of the second playback device receiving the audio packet, and updating the audio packet to the second audio packet set if the second reception condition represents that the second playback device fails to successfully receive; sending a second confirmation signal to the sound source device, or sending the second confirmation signal to the sound source device through the second playback device, so that the sound source device transmits a next audio packet through a next Bluetooth downlink frame.

13. The audio transmission method of claim 12, wherein, The method further comprises: sending an audio packet negative acknowledgement signal to the second playback device or not sending the audio packet reception success signal to the second playback device in response to the audio packet not being correctly received, so that the second playback device updates the audio packet to the first audio packet set.

14. A playback device, comprising: a Bluetooth module, configured to establish a first Bluetooth connection with a sound source device or establish a second Bluetooth connection with another playback device in a truly wireless playback device through a first Bluetooth connection established by the another playback device with the sound source device, receive a Bluetooth downlink frame transmitted by the sound source device, and send at least one second historical audio packet in a second audio packet set to the another playback device based on the second audio packet set before receiving a next Bluetooth downlink frame transmitted by the sound source device when a forwarding direction of an audio packet is to the another playback device, or attempt to receive at least one first historical audio packet in a first audio packet set transmitted by the another playback device based on the first audio packet set before receiving the next Bluetooth downlink frame transmitted by the sound source device when the forwarding direction of the audio packet is to the playback device, wherein the Bluetooth downlink frame is used to transmit an audio packet, the second audio packet set is a sequence of second historical audio packets that are unsuccessfully received by the another playback device from the sound source device, and the first audio packet set is a sequence of first historical audio packets that are unsuccessfully received by the playback device from the sound source device; a processing module, configured to verify the Bluetooth downlink frame by sequentially passing through a plurality of detection stages, stop continuing to detect the Bluetooth downlink frame in response to a failure in access code detection, and / or a failure in packet header detection, and / or a determination that the Bluetooth downlink frame has no payload based on packet header field analysis, and determine a forwarding direction of the audio packet identified by a current forwarding state flag, wherein the plurality of detection stages include an access code detection stage and a packet header detection stage.

15. A truly wireless playback device, comprising: two playback devices, wherein at least one of the playback devices is configured to perform the audio transmission method in any one of claims 1-13.

16. An audio transmission system, comprising: a sound source device, configured to transmit a Bluetooth downlink frame used to transmit an audio packet; the truly wireless playback device in claim 15, in Bluetooth connection with the sound source device, configured to receive the audio packet.

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