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 retransmission audio packet sent by sound source equipment; determining an audio packet forwarding direction identified by the current forwarding state flag; if the retransmission audio packet is forwarded to the second playing device, in response to the detection failure of the Bluetooth synchronous code corresponding to the retransmission audio packet or the reception of the audio packet, sending a second historical audio packet to the second playing device based on the second audio packet set in the current sub-event time window; and if the retransmission audio packet is forwarded to the first playing device, in response to the detection failure of the Bluetooth synchronous code corresponding to the retransmission audio packet or the reception of the audio packet, trying to receive a first historical audio packet sent by the second playing device based on the first audio packet set in the current sub-event time window. The audio packet receiving capability of the playing device is enhanced, the transmission frequency between the devices is reduced, and the power consumption is saved.

Description

Technical Field

[0001] This disclosure relates to the field of communication and interaction technology, specifically to an audio transmission method, a playback device, a true wireless playback device, and an audio transmission system. Background Technology

[0002] For applications involving audio playback via true wireless playback devices, the true wireless playback device can receive audio packets sent by the audio source device through LE link layer data packets based on the Bluetooth connection between the two devices, and then play the audio.

[0003] In related technologies, audio packets sent by the audio source device via LE link layer data packets will only be sent via the next LE link layer data packet after receiving an acknowledgment (ACK) from the true wireless playback device or reaching the maximum retransmission limit.

[0004] However, if the Bluetooth connection quality between the audio source device and the true wireless playback device is poor, the audio source device will retransmit audio packets more often, affecting the audio playback quality. Moreover, because the audio source device retransmits more often, it will also increase the number of communications between the devices, increasing the power consumption of the true wireless playback device, shortening the usage time of the true wireless playback device, and affecting the user experience. Summary of the Invention

[0005] To overcome the problems existing in related technologies, an exemplary embodiment of this disclosure provides an audio transmission method applied to a first playback device in a true wireless playback device. The first playback device is connected to a second playback device in the true wireless playback device via Bluetooth and receives audio packets from an audio source device in any of the following ways: receiving audio packets in a time stream such as establishing a connection with the audio source device, receiving audio packets in a time stream such as establishing a broadcast with the audio source device, receiving audio packets in a time stream such as listening to the connection established between the second playback device and the audio source device, and receiving audio packets in a time stream such as listening to the broadcast established between the second playback device and the audio source device. The method includes: receiving retransmitted audio packets sent by the audio source device, wherein the retransmitted audio packets are audio packets repeatedly sent within a time window for a corresponding sub-event; determining the forwarding direction of the audio packets identified by the current forwarding status flag; if the audio packets... If the forwarding direction is to the second playback device, then in response to the failure to detect the Bluetooth synchronization code corresponding to the retransmitted audio packet or the retransmitted audio packet being correctly received, within the current sub-event time window, at least one second historical audio packet from the second audio packet set is sent to the second playback device based on the second audio packet set, wherein 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; if the audio packet forwarding direction is to the first playback device, then in response to the failure to detect the Bluetooth synchronization code corresponding to the retransmitted audio packet or the retransmitted audio packet being correctly received, within the current sub-event time window, an attempt is made 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, wherein 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.

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

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

[0008] In some embodiments, the method further includes: sending an audio packet forwarding direction to a second playback device; or sending a second cumulative number to a second playback device so that the second playback device determines the audio packet forwarding direction.

[0009] In some embodiments, determining the audio packet forwarding direction identified by the current forwarding status flag includes: sending a second cumulative number to a 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, within the current sub-event time window, sending at least one second historical audio packet from the second audio packet set to the second playback device based on the second audio packet set includes: after a first moment when a retransmitted audio packet is received, sending the second historical audio packet to the second playback device based on the second audio packet set, wherein the frequency at which the first playback device sends the second historical audio packet is different from the frequency at which the audio source device sends the retransmitted audio packet; within the current sub-event time window, attempting 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 includes: after a second moment when a retransmitted audio packet 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 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 retransmitted audio packet.

[0011] In some embodiments, both the first and second moments are later than the end time of the period occupied by the Bluetooth synchronization code.

[0012] In some embodiments, the method further includes: receiving a second forwarding success notification sent by a second playback device, wherein the second forwarding success notification is sent by the second playback device in response to successfully receiving a 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 includes: in response to successfully receiving a first historical audio packet, sending a first forwarding success notification to a second playback device to cause the second playback device to update the first audio packet set.

[0014] In some embodiments, the method further includes: in response to the retransmitted audio packet being correctly received, sending an audio packet reception success signal to the second playback device; determining a second reception status of the retransmitted audio packet received by the second playback device, and if the second reception status indicates that the second playback device has not successfully received the packet, then sending the retransmitted audio packet as a Bluetooth packet to update the second audio packet set.

[0015] In some embodiments, the method further includes: in response to a retransmitted audio packet not being received correctly, 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 retransmitted audio packet to the first audio packet set.

[0016] Secondly, this disclosure also provides a playback device, including: a Bluetooth module, configured to establish a Bluetooth connection with another playback device in a true wireless playback device, and to receive audio packets from an audio source device in any of the following ways: receiving audio packets via a connection established with the audio source device, receiving audio packets via a broadcast established with the audio source device, receiving audio packets via a listening connection established between another playback device and the audio source device, receiving audio packets via a listening connection established between another playback device and the audio source device; receiving retransmitted audio packets sent by the audio source device, wherein when the audio packet forwarding direction is to another playback device, in response to the failure of Bluetooth synchronization code detection for the retransmitted audio packet or the retransmitted audio packet being correctly received, within the current sub-event time window, based on the second audio... The first audio packet set is used to send at least one second historical audio packet from the second audio packet set to another playback device. Alternatively, when the audio packet forwarding direction is to forward to the playback device, in response to the failure of Bluetooth synchronization code detection for the retransmitted audio packet or the retransmitted audio packet being correctly received, within the current sub-event time window, an attempt is made to receive at least one first historical audio packet from the first audio packet set sent by another playback device based on the first audio packet set. Here, the retransmitted audio packet is used to transmit audio packets that need to be retransmitted, the second audio packet set is the sequence of second historical audio packets that the other playback device failed to receive from the audio source device, and the first audio packet set is the sequence of first historical audio packets that the playback device failed to receive from the audio source device. The processing module is used to determine the audio packet forwarding direction indicated by the current forwarding status flag.

[0017] Thirdly, this disclosure also provides a true wireless playback device, comprising: two playback devices, wherein at least one playback device is used to perform the audio transmission method provided in any of the above aspects.

[0018] Fourthly, this disclosure also provides an audio transmission system, comprising: an audio source device for sending LE link layer data packets, the LE link layer data packets being used to transmit audio packets; and a true wireless playback device provided in any of the above aspects, connected to the audio source device via Bluetooth, for receiving audio packets.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure.

[0020] The technical solutions provided by the embodiments of this disclosure can include the following beneficial effects: According to the audio transmission method provided by this disclosure, in the application scenario where the audio source device sends retransmitted audio packets, when the first playback device determines that the reception has failed or has already successfully received the retransmitted audio packet, it can stop the communication interaction with the audio source device, and determine the audio packet transmission and reception relationship between the first playback device and the second playback device based on the audio packet forwarding direction indicated by the current forwarding status flag. Then, by utilizing the idle time within the current sub-event time window of receiving the audio source device, the audio packets within the device are forwarded 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 of 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. Attached Figure Description

[0021] This disclosure can be better understood by describing exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram of the architecture of an audio transmission system according to an exemplary embodiment disclosed in a publication; Figure 2 This is a flowchart illustrating an audio transmission method according to an exemplary embodiment of a published document; Figure 3 This is a schematic diagram of the structure of a physical frame according to an exemplary embodiment disclosed in a book; Figure 4 This is a flowchart illustrating another audio transmission method according to an exemplary embodiment of a published document; Figure 5 This is an interactive timing diagram illustrating an audio transmission according to an exemplary embodiment disclosed in a book. Figure 6 This is a schematic diagram of the structure of a playback device according to an exemplary embodiment disclosed in a publication; Figure 7 This is a schematic diagram of the structure of an audio transmission system according to an exemplary embodiment disclosed in a book. Detailed Implementation

[0022] The following describes specific embodiments of this disclosure. It should be noted that, in order to provide a concise description, this specification cannot exhaustively describe all features of the actual embodiments. It should be understood that, in the actual implementation of any embodiment, just as in any engineering or design project, various specific decisions are often made to achieve the developer's specific goals and to meet system-related or business-related constraints, and this can change from one embodiment to another. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this disclosure, changes in design, manufacturing, or production based on the technical content disclosed in this disclosure are merely conventional technical means and should not be construed as insufficient content of this disclosure.

[0023] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms “a” or “one,” etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” etc., mean that the element or object preceding “comprising” or “including” encompasses the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected,” “linked,” etc., are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0024] For applications involving audio playback via true wireless playback devices, the two playback devices in a true wireless playback device can receive audio packets sent by the audio source device through LE link layer data packets based on the Bluetooth connection between the two devices, and then play the audio.

[0025] For example, taking true wireless stereo (TWS) earbuds as a true wireless playback device, the Bluetooth connection between the earbuds and the audio source device can be as follows: Figure 1As shown. The true wireless earbuds include earbud 1 and earbud 2. The true wireless earbuds can receive audio signals from the audio source device based on Low Energy Bluetooth (LE) audio technology (a new audio function defined in Bluetooth protocol version 5.2). LE audio technology can include Low Energy Audio technology or Bluetooth Low Energy Audio technology. A Connected Isochronous Group (CIG) or a Broadcast Isochronous Group (BIG) can be pre-established between the true wireless earbuds and the audio source device. A Connected Isochronous Group (CIG) is a logical group composed of one or more Connected Isochronous Streams (CIS), which coordinates the CIS within the group to ensure precise data synchronization between multiple connection points. A Broadcast Isochronous Group (BIG) is a logical group composed of one or more Broadcast Isochronous Streams (BIS), where all BIS share the same timing parameters (such as interval and delay), ensuring synchronous data transmission between multiple receiving devices.

[0026] In related technologies, the process of receiving audio packets through an audio source device via true wireless earbuds can include the following: The first method: The audio source device establishes a CIG connection, the earphone 1 establishes a CIS connection 1 with the audio source device, the earphone 2 establishes a CIS connection 2 with the audio source device, the earphone 1 receives audio packets through the CIS connection 1, and the earphone 2 receives audio packets through the CIS connection 2. The second method involves the audio source device establishing a BIG, and earphones 1 and 2 synchronizing and joining the BIG, receiving BIS index 1, and receiving the corresponding audio packets. In other words, earphones 1 and 2 receive audio packets via BIS index 1. Of course, the audio source device sends audio packets via BIS index 1 so that the earphones can receive them. The third method: The audio source device establishes a CIG connection, and either earphone A of earphone 1 or earphone 2 establishes a CIS connection 1 with the audio source device and receives audio; the other earphone B listens to the CIS connection 1 and receives audio packets. The fourth method involves the audio source device establishing a BIG, synchronizing with either earphone C in earphone 1 and earphone 2, adding it to the BIG, receiving BIS index 1, and receiving its corresponding audio packets; the other earphone listens to the BIS index 1 added by earphone C and receives its corresponding audio packets; of course, the audio source device sends audio packets through BIS index 1 so that the earphones can receive them.

[0027] In a pre-defined CIS or BIS, the audio packet is retransmitted more than once. In LE audio, whether implemented via CIG / CIS or BIG / BIS, the same audio packet can be retransmitted multiple times to improve the ability of playback devices such as headphones to receive audio packets. The retransmission count is typically 2, 3, 4, 5, etc. In CIS / BIS, multiple retransmissions of audio packets can be achieved through multiple CIS / BIS sub-event time windows. N1 retransmissions of audio packets can be accomplished by N1 CIS / BIS sub-events. Therefore, the NSE (Number of Subevents) in CIS / BIS is greater than or equal to the number of audio packet retransmissions.

[0028] In multiple retransmissions of the same audio packet, the audio packet corresponding to the first CIS / BIS sub-event can be called the initial audio packet; the audio packets corresponding to subsequent retransmissions of the same CIS / BIS sub-event can be called retransmission audio packets. These audio packets are all sent from the audio source device to the playback device. An audio packet can refer to a data packet, specifically a Protocol Data Unit (ISO PDU).

[0029] In some embodiments, for playback device 1 in a true wireless playback device to listen for CIS or BIS sub-events of playback device 2, playback device 1 and playback device 2 are interconnected via Bluetooth connection 2. Through Bluetooth connection 2, playback device 1 transmits CIS or BIS sub-event related parameters to playback device 2, so that playback device 2 can listen for and receive CIS or BIS sub-events from the audio source device. The CIS or BIS sub-event related parameters include the Bluetooth address of the audio source device and Bluetooth frequency hopping information. BIS sub-event related parameters also include periodic broadcast (PA) synchronization parameters, BIGInfo, etc. CIS sub-event related parameters also include CIG / CIS identifiers, Published Audio Capabilities Service (PACS), QoS parameters, etc. Based on the CIS or BIS sub-event related parameters, playback device 2 listens for and receives CIS or BIS sub-events from the audio source device.

[0030] However, if the Bluetooth connection quality between the audio source device and the true wireless playback device is poor, the audio source device will resend audio packets more often due to not receiving confirmation signals, affecting the audio playback quality. Moreover, because the audio source device resends more often, it will also increase the number of communications between the devices, increasing the power consumption of the true wireless playback device, shortening the usage time of the true wireless playback device, and affecting the user experience.

[0031] In view of this, the present 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 connects to a second playback device in the true wireless playback device via Bluetooth and can receive audio packets from an audio source device via Bluetooth Low Energy. Specifically, it can receive audio packets from the audio source device in any of the following ways: A. The audio source device establishes a CIG connection. The first playback device receives audio packets by establishing a CIS (connected isochronous stream) connection with the audio source device. The second playback device also establishes a CIS connection with the audio source device.

[0032] B. The audio source device establishes a BIG. The first and second playback devices synchronize and join the BIG, receive the BIS index, and receive the corresponding audio packets. The first playback device receives audio packets by establishing a BIS (Broadcast Isochronous Stream) with the audio source device.

[0033] C. The audio source device establishes a CIG (Connection Information Group). The first playback device receives audio packets by listening to the CIS (Connection Information Group System) established between the second playback device and the audio source device. Similarly, the first playback device can establish a CIS with the audio source device, and the second playback device can obtain audio packets by listening to the CIS established by the first playback device.

[0034] D. The audio source device establishes a BIG (Broadcast Isochronous Stream). The first playback device obtains audio packets by listening to the connection established between the second playback device and the audio source device and receiving the BIS (Broadcast Isochronous Stream) index. Similarly, the first playback device can also establish a BIS with the audio source device, and the second playback device obtains audio packets by listening to the connection established by the first playback device and receiving the BIS (Broadcast Isochronous Stream) index.

[0035] The first playback device can be any of the true wireless playback devices. The audio source device can be a smartphone, tablet, laptop, or various smart devices. 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.

[0036] like Figure 2 As shown, the audio transmission method provided in this disclosure may include the following steps: Step S210: Receive the retransmitted audio packet sent by the audio source device.

[0037] A retransmitted audio packet is an audio packet repeatedly sent within the time window of a corresponding sub-event. In this application, the retransmitted audio packet refers to the retransmission of CIS or BIS, which involves repeatedly sending the same ISO PDU (same payload / same fragment / same data packet). That is, the audio packet to be retransmitted has already been sent by the audio source device to two playback devices, but at least one of the first and second playback devices failed to receive it successfully, or it is unknown whether the audio source was successfully received. Therefore, it needs to be retransmitted again through this retransmitted audio packet. The retransmitted audio packet is sent more than once during the entire audio transmission process. For example, the retransmitted audio packet may be resent to the true wireless playback device for the 2nd, 3rd, or 4th time.

[0038] If the connection between the audio source device and the true wireless playback device is CIG, the first audio playback device can receive the retransmitted audio packet based on CIS; if the connection between the audio source device and the true wireless playback device is BIG, the first audio playback device can receive the retransmitted audio packet based on BIS. The specific reception method can be determined according to the connection mode between the audio source device and the true wireless playback device.

[0039] Step S220: Determine the forwarding direction of the audio packet indicated by the current forwarding status flag.

[0040] The physical frame structure of LE link layer packets can be as follows: Figure 3 As shown. The LE link layer data packet includes four fields, arranged from least significant bit to most significant bit: Preamble 301, Access Address 302, Link Layer Header 303, and Payload 304. The CRC (Cyclic Redundancy Check) field at the end of the frame is not shown. In this disclosure, the audio packet refers to the audio data corresponding to Payload 304 in the Bluetooth physical frame, and the Bluetooth synchronization code refers to the combination of Preamble 301 and Access Address 302.

[0041] In response to a received retransmitted audio packet, the first audio playback device checks each field of the physical frame structure of the retransmitted audio packet to determine if it can successfully receive it. If the Bluetooth synchronization code detection result for the retransmitted audio packet is successful, subsequent detection continues, parsing the data information of the repeatedly sent audio packet from the packet header to correctly receive the retransmitted audio packet. However, if the Bluetooth synchronization code detection result fails, the first audio playback device will not be able to continue detecting the retransmitted audio packet, will determine it as an invalid frame, and will therefore be unable to obtain the audio packet to be retransmitted. The Bluetooth synchronization code detection serves several purposes: determining whether there is an LE link layer data packet carrying a specified access code or synchronization code on the air interface, locating the frame start position, and correcting symbol timing and frequency offset, providing the basic conditions for receiving subsequent LE link layer data packets. This detection can also be used to determine whether the current LE link layer data packet belongs to a predetermined CIS / BIS sub-event sent by the audio source device. A synchronization code detection failure indicates both the failure to receive the corresponding retransmitted audio packet and the failure to receive the corresponding CIS / BIS sub-event. The failure may be due to the absence of an LE link layer data packet carrying the specified synchronization code on the air interface, or the LE link layer data packet corresponding to the specified synchronization code having a weak signal strength, a low signal-to-noise ratio, or being severely affected by airborne radio frequency interference.

[0042] Because the audio source device has a certain length of time within the current sub-event time window, there is a period of idle time before the next sub-event time window if it is determined that the retransmission of the audio packet has failed (such as Bluetooth synchronization code detection failure).

[0043] Alternatively, in response to a received retransmitted audio packet, the first audio playback device can detect that the retransmitted audio packet has been correctly received and then stop receiving the retransmitted audio packet, thus creating a period of idle time within the current sub-event time window.

[0044] Therefore, in this disclosure, the audio packet forwarding direction 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, idle time within the corresponding sub-event time window can be utilized to achieve intra-device (between the first and second playback devices) audio packet forwarding, supplementing any missing audio packets in 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 in 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 S230, if the audio packet forwarding direction is to the second playback device, then in response to the failure of Bluetooth synchronization code detection for the retransmitted audio packet or the retransmitted audio packet being correctly received, within the current sub-event time window, at least one second historical audio packet from 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: the first playback device acts as the sender, and the second playback device acts as the receiver. Therefore, within the current sub-event time window, the first playback device can temporarily interrupt its communication with the audio source device, thus fully utilizing this idle time to send second historical audio packets to the second playback device based on the second audio packet set. This allows the device to supplement missing historical audio packets as much as possible through its internal audio packet forwarding mechanism, enhancing its ability to receive audio packets and ensuring the audio playback quality of the second playback device. 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's history. During a single transmission, one or more audio packets stored in the second audio packet set can be sent according to their order of inclusion, or all audio packets in the second audio packet set can be sent together.

[0047] In step S240, if the audio packet forwarding direction is to the first playback device, then in response to the failure of Bluetooth synchronization code detection for the retransmitted audio packet or the retransmitted audio packet being correctly received, within the current sub-event time window, an attempt is made 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.

[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: the first playback device acts as the receiver, and the second playback device acts as the sender. Therefore, within the current sub-event time window, the first playback device can temporarily interrupt its communication with the audio source device, thus fully utilizing this idle time to attempt to receive the first historical audio packets sent by the second playback device based on the first audio packet set. This allows the device to supplement any missing audio packets in its history as much as possible through the audio packet forwarding method, 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 packets are the audio packets that were previously missing from 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, in the application scenario where the audio source device sends a retransmitted audio packet, if the first playback device determines that the reception has failed or has already successfully received the retransmitted audio packet, it can stop 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, it utilizes the idle time within the current sub-event time window to forward 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, improved Bluetooth protocol, or other wireless transmission protocols, and proprietary wireless transmission protocols. For example, the payload of the forwarded audio packet may use a higher modulation order than the existing LE link layer data packets, such as QAM16 or QAM64; the physical frame of the forwarded historical audio packet may also use a higher symbol rate, such as 2M symbols / s, 3M symbols / s, or 4M symbols / s. In this way, the existing Bluetooth module can be fully reused, the transmission rate of the forwarded audio packet can be improved, thereby improving the transmission reliability of the forwarded historical audio packet and shortening its transmission time, so that the transmission of the forwarded audio packet can be completed within the idle time of the sub-event time window where the retransmitted audio packet is located.

[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 audio packet, the first playback device will interact with the second playback device to check the reception status of the audio packets received from the audio device. Therefore, the two playback devices can determine whether the other party 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 method.

[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 understand the audio forwarding method, the first playback device 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 the transmission efficiency of audio packets.

[0066] In some embodiments, the audio packet forwarding direction may also include "none," indicating that no in-device audio packet forwarding is required. That is, when neither the first playback device nor the second playback device has any missing historical audio packets, both the first audio packet set and the second audio packet set are empty sets. In this case, the current forwarding status flag can be determined to indicate that forwarding is not required, and the audio packet forwarding direction is "none." This allows control to prevent either playback device from performing any possible forwarding operations during idle periods, thereby reducing power consumption and minimizing the occupation of airborne wireless resources.

[0067] In some embodiments, step S230 may include: after the first moment when the retransmitted audio packet is received, sending at least one second historical audio packet from the second audio packet set to the second playback device based on the second audio packet set. The current sub-event time window in which the retransmitted audio packet is received has a certain duration. To avoid affecting the normal reception of the retransmitted audio packet by the second playback device, when the audio forwarding direction is determined to be forwarding to the second audio device, the system controls the sending of the second historical audio packet to the second playback device after the first moment when the retransmitted audio packet is received, based on the second audio packet set. This allows the second playback device to attempt to receive the second historical audio packet within the current sub-event time window, thereby enhancing the audio packet reception capability of the second playback device and ensuring the integrity of the received audio packets. 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 at which the first playback device sends the second historical audio packet is different from the frequency at which the audio source device sends the retransmitted audio packet, thus helping to prevent the retransmitted audio packet sent by the audio source device from interfering with the internal audio packet forwarding of the device.

[0068] 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 retransmitted audio packet 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 the audio packet reception and improving the audio packet reception success rate.

[0069] 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.

[0070] In some embodiments, step S240 may include: after a second moment when a retransmitted audio packet is received, attempting 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. 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 retransmitted audio packet, thereby helping to avoid interference from the retransmitted audio packet sent by the audio source device with the internal audio packet forwarding of the device.

[0071] 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 retransmitted audio packet at the second moment, 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 receiving capability, ensure the integrity of audio packet reception, and improve the success rate of audio packet reception.

[0072] 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 retransmitted audio packet is received, so that the first playback device may attempt to receive the first historical audio packet within the current sub-event time window, thereby enhancing the audio packet receiving capability of the first playback device and ensuring the integrity of the audio packet reception.

[0073] 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.

[0074] In some embodiments, both the first and second moments are later than the end time of the period occupied by the Bluetooth synchronization code. This ensures that the audio packet forwarding process within the device will not affect the normal reception of retransmitted audio packets sent by the audio source device by the first and second playback devices, ensuring that frame transmission between devices and audio packet forwarding within the device can proceed in an orderly manner, avoiding air interface conflicts. For example, the Bluetooth synchronization code includes a preamble and an access code. In LE 1M mode, the preamble occupies 8μs and the access code occupies 32μs. Therefore, when configuring the first and second moments, they can be configured to be later than 40μs and before receiving the next sub-event time window, ensuring that at least one historical audio packet can be completely transmitted. Alternatively, in LE 2M mode, the preamble occupies 8μs and the access code occupies 16μs. Therefore, when configuring the first and second moments, they can be configured to be later than 24μs and before receiving the next sub-event time window, ensuring that at least one historical audio packet can be completely transmitted.

[0075] In other embodiments, the first, second, third, and fourth moments are all later than the end time of the period occupied by the Bluetooth synchronization code, so that both the first and second playback devices can receive the retransmitted audio packets normally. This allows for audio packet forwarding within the device without affecting the correct reception of the retransmitted audio packets, thereby improving the success rate of the playback device receiving audio packets.

[0076] 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.

[0077] In some embodiments, such as Figure 4 As shown, the audio transmission method may further include the following steps: Step S250: Receive the second forwarding success notification sent by the second playback device.

[0078] 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.

[0079] Step S260: Update the second audio packet set based on the second forwarding success notification.

[0080] 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.

[0081] In other embodiments, such as Figure 4 As shown, the audio transmission method may further include the following steps: In step S270, 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.

[0082] 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.

[0083] In some embodiments, the audio transmission method may further include: Step S280: In response to the successful detection of the Bluetooth synchronization code corresponding to the retransmitted audio packet and the fact that the retransmitted audio packet has not been correctly received, obtain the retransmitted audio packet.

[0084] If the retransmitted audio packet was not successfully received before the first playback device was identified, and the detection result of the Bluetooth synchronization code detection was successful, it indicates that the retransmitted audio packet is a valid frame. The first playback device can correctly receive the retransmitted audio packet and thus receive the retransmitted audio packet to ensure the complete reception of the audio packet.

[0085] 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 retransmitted audio packet has been successfully received. When the second playback device is the master device, the first playback device can send a reception success signal to the second playback device, causing the second playback device to send a first acknowledgment signal to the audio source device.

[0086] In some embodiments, the audio transmission method may further include the following steps: in response to the correct reception of a retransmitted audio packet, the first playback device sends an audio packet reception success signal to the second playback device; determining a second reception status of the retransmitted audio packet received by the second playback device, and if the second reception status indicates that the second playback device has not successfully received the packet, then the retransmitted audio packet is added as an update to the second audio packet set. By determining the second reception status of the first audio packet received by the second playback device, it can be determined whether the second playback device has successfully received the retransmitted audio packet. In the case of unsuccessful reception, the audio packet can be used as a second historical audio packet and updated to the second audio packet set.

[0087] In some embodiments, the audio transmission method may further include the following steps: Step c1: Receive the first audio packet sent by the audio source device, also known as the initial audio packet; Step c2: In response to the successful reception of the first audio packet, a signal indicating successful audio packet reception is sent to the second playback device. Step c3: Determine the second reception status of the second playback device receiving the first audio packet. If the second reception status indicates that the second playback device has not successfully received the first audio packet, then use the first audio packet as the second historical audio packet and update the second audio packet set. Step c4: 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.

[0088] The first audio packet refers to the first audio packet transmitted via the LE link layer data packet for the same audio packet. Therefore, the LE link layer data packet used to transmit the first audio packet can be called the first Bluetooth packet. For the first Bluetooth packet, if the first playback device can correctly receive it, it sends an audio packet reception success signal to the second playback device to inform it that it has successfully received the first audio packet transmitted via the first Bluetooth packet. Subsequently, regardless of whether the second playback device can successfully receive the first audio packet, it does not need to update the first audio packet set.

[0089] 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.

[0090] 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.

[0091] Once the first playback device successfully receives the initial 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. This prevents the audio source device from needing to retransmit the same audio packet, thus 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, thereby effectively extending the usage time.

[0092] According to the audio transmission method provided in this disclosure, for the first Bluetooth packet, as long as the first playback device can successfully receive it, a second confirmation signal can be sent to the audio source device. Subsequently, the historical audio packets can be supplemented only through Bluetooth transmission 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.

[0093] Furthermore, by not performing Bluetooth packet transmission within the device during the initial Bluetooth packet transmission process, the increased power consumption of the playback device caused by the additional audio packet forwarding between the two playback devices can be greatly reduced.

[0094] In some embodiments, the audio transmission method may further include: in response to the first audio packet not being received correctly, sending an audio packet negative acknowledgment signal to the second playback device or not interacting with the second playback device, so that the second playback device uses the first audio packet as the first historical audio packet and updates the first audio packet set, so that the first audio packet missing by the first playback device can be synchronized with the first audio packet set stored in the second playback device, thereby helping to ensure the consistency of missing records between the two playback devices and avoiding duplicate or missed transmissions.

[0095] In some embodiments, the first playback device and the second playback device each have a Bluetooth module, and each playback device has only one Bluetooth module. Therefore, a time-division multiplexing method is used for connection based on different connection objects to reduce hardware costs. For example, the first playback device includes a first Bluetooth module, which connects to the audio source device and the second playback device via Bluetooth. The Bluetooth links between the first playback device and the audio source device and between the first playback device and the second playback device operate alternately in time-division duplex mode, meaning that only one connection object is maintained within the same time slice.

[0096] In some optional application scenarios, taking true wireless playback devices as true wireless earbuds as an example, combined with Figure 1 The 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. Each earbud has a Bluetooth module. The Bluetooth connection between either earbud and the audio source device, as well as the Bluetooth connection with the other earbud, is achieved through time-division multiplexing of the internal Bluetooth module. Missing packet information can be transmitted between earbuds 1 and 2 via a forwarded connection between them, or via another private wireless connection between them.

[0097] 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.

[0098] like Figure 5 As shown, within the predetermined sub-event time window (the time interval between the start time of the LE link layer data packet containing the retransmitted audio packet and the start time of the next sub-event time window), the audio source device sends out the retransmitted audio packet. Figure 5The TX0 of the audio source device and the headphone 1 detect the received retransmitted audio packets. Figure 5 (RX0 of earphone 1). If earphone 1 fails to detect the Bluetooth synchronization code corresponding to the retransmitted audio packet or the retransmitted audio packet has been correctly received, and the audio packet forwarding direction is to earphone 2, then after the first moment T1 when the retransmitted audio packet is received, the second historical audio packet is forwarded to earphone 2. Figure 5 The Relay_TX0 of earphone 1). If earphone 2 fails to detect the Bluetooth synchronization code corresponding to the retransmitted audio packet, and the audio packet forwarding direction is to earphone 2, then after time T3 when the retransmitted audio packet is received, the second historical audio packet forwarded from earphone 1 will be received ( Figure 5 (Relay_RX0 of the second earphone). Figure 5 The text only shows the process of earphone 1 forwarding the second historical audio packet to earphone 2, and earphone 2's RX0 is used for the received retransmitted audio packet.

[0099] Similarly, if earphone 2 fails to detect the Bluetooth synchronization code corresponding to the retransmitted audio packet or the retransmitted audio packet has been correctly received, and the audio packet is forwarded to earphone 1, then after time T4 (the fourth time after the retransmitted audio packet is received), it forwards the first historical audio packet to earphone 1. If earphone 1 fails to detect the Bluetooth synchronization code for the retransmitted audio packet, and the audio packet is forwarded to earphone 1, then after time T2 (the second time after the retransmitted audio packet is received), it receives the forwarded first historical audio packet from earphone 2.

[0100] Based on the same inventive concept, this disclosure also provides a playback device. For example... Figure 6 As shown, the playback device 400 may include: Bluetooth module 410 is used to establish a first Bluetooth connection with an audio source device, establish a Bluetooth connection with another playback device in a true wireless playback device, and receive audio packets from the audio source device in any of the following ways: receiving audio packets via a connection establishment time stream, receiving audio packets via a broadcast establishment time stream, receiving audio packets via a connection established between another playback device and the audio source device, or receiving audio packets via a broadcast establishment time stream; receiving retransmitted audio packets sent by the audio source device, when the audio packet forwarding direction is to another playback device, responding to the failure of Bluetooth synchronization code detection for the retransmitted audio packet or the retransmitted audio packet being correctly received, within the current sub-event time window. Within the mouth, based on the second audio packet set, at least one second historical audio packet in the second audio packet set is sent to another playback device; or, when the audio packet forwarding direction is forwarding to the playback device, in response to the failure of Bluetooth synchronization code detection for retransmitted audio packets or the retransmitted audio packets being correctly received, within the current sub-event time window, an attempt is made 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, wherein the retransmitted audio packet is an audio packet repeatedly sent within the time window of the corresponding sub-event, the second audio packet set is a sequence of second historical audio packets that the other playback device failed to receive from the audio source device, and the first audio packet set is a sequence of first historical audio packets that the playback device failed to receive from the audio source device; Processing module 420 is used to determine the forwarding direction of the audio packet identified by the current forwarding status flag.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] Based on the same inventive concept, this disclosure also provides an audio transmission system. For example... Figure 7 As shown, the audio transmission system 500 may include: Audio source device 510 is used to send LE link layer data packets, 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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 Bluetooth connection, and receiving an audio packet from a sound source device in any one of the following ways: receiving the audio packet through a connection isochronous stream established with the sound source device, receiving the audio packet through a broadcast isochronous stream established with the sound source device, receiving the audio packet by listening to a connection isochronous stream established between the second playback device and the sound source device, and receiving the audio packet by listening to a broadcast isochronous stream established between the second playback device and the sound source device. The audio transmission method comprises: receiving a retransmitted audio packet sent by the audio source device, wherein the retransmitted audio packet is an audio packet repeatedly sent within a time window of a corresponding sub-event; 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 a Bluetooth synchronization code detection failure corresponding to the retransmitted audio packet or the retransmitted audio packet having been correctly received, within a current sub-event time window, at least one second historical audio packet in a second audio packet set is sent 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 a Bluetooth synchronization code detection failure corresponding to the retransmitted audio packet or the retransmitted audio packet having been correctly received, within a current sub-event time window, an attempt is made 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; 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 forward to the second playback device.

4. The audio transmission method of 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, within a current sub-event time window, 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 comprises: after a first time point at which the retransmission audio packet is received, sending, to the second playback device, a second historical audio packet based on the second audio packet set, wherein a frequency point at which the first playback device sends the second historical audio packet is different from a frequency point at which the sound source device sends the retransmission audio packet; the attempting to receive, within the current sub-event time window, 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 comprises: after a second time point at which the retransmission audio packet is received, attempting to receive a first historical audio packet sent by the second playback device based on the 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 retransmission audio packet.

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 the period occupied by the Bluetooth synchronization code.

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 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 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 correct reception of the retransmission audio packet, sending an audio packet reception success signal to the second playback device; determining a second reception condition of the second playback device receiving the retransmission audio packet, and in a case where the second reception condition indicates that the second playback device fails to successfully receive, updating the retransmission audio packet to the second audio packet set.

11. The audio transmission method of claim 10, wherein, The method further comprises: in response to incorrect reception of the retransmission audio packet, 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, to enable the second playback device to update the retransmission audio packet to the first audio packet set.

12. A playback device, comprising: The Bluetooth module is configured to establish a Bluetooth connection with another playback device in the truly wireless playback system, and receive an audio packet from the audio source device in any of the following ways: receiving the audio packet through a connection isochronous stream established with the audio source device, receiving the audio packet through a broadcast isochronous stream established with the audio source device, receiving the audio packet by listening to a connection isochronous stream established between the another playback device and the audio source device, receiving the audio packet by listening to a broadcast isochronous stream established between the another playback device and the audio source device; receiving a retransmission audio packet sent by the audio source device, and when the audio packet forwarding direction is to forward to the another playback device, in response to a Bluetooth synchronization code corresponding to the retransmission audio packet failing to be detected or the retransmission audio packet being correctly received, sending, within a current sub-event time window, 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, or when the audio packet forwarding direction is to forward to the playback device, in response to the Bluetooth synchronization code corresponding to the retransmission audio packet failing to be detected or the retransmission audio packet being correctly received, attempting to receive, within the current sub-event time window, at least one first historical audio packet in a first audio packet set sent by the another playback device based on the first audio packet set, wherein the retransmission audio packet is an audio packet repeatedly sent within a time window of a corresponding sub-event, the second audio packet set is a second historical audio packet sequence that the another playback device fails to successfully receive from the audio 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 audio source device. The processing module is configured to determine an audio packet forwarding direction identified by a current forwarding state flag.

13. 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 of any of claims 1-11.

14. An audio transmission system, comprising: an audio source device configured to send LE link layer data packets, the LE link layer data packets being used to transmit audio packets ； the truly wireless playback device of claim 13, which is in a Bluetooth connection with the audio source device and is configured to receive the audio packets.

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