Audio system control method and audio system

Abstract

An audio system control method includes: (a) establishing an OOB wireless communication channel between a first audio playback device and a second audio playback device; (b) when the first audio playback device is ready to play audio data, calculating a first time difference between a current time point and a first expected playback time point; (c) if the current time point is before the first expected playback time point, transmitting a preparation notification to the second audio playback device through the OOB wireless communication channel; (d) if the second audio playback device has received the preparation notification and is ready to play audio data, transmitting a start playback notification to the first audio playback device through the OOB wireless communication channel; and (e) after the first audio playback device receives the start playback notification, the first audio playback device and the second audio playback device begin playing audio data.

Description

[Technical Field]

[0001] The present invention relates to an audio system control method and an audio system, and particularly to an audio system control method and an audio system that can reduce audio playback delay. [Previous Technology]

[0002] With the advancement of technology, Bluetooth headphones have become increasingly popular. However, if different Bluetooth headphones in a pair have different performance levels, the higher-performance headphone will reduce its audio playback speed in order to synchronize with the lower-performance headphone while adhering to the Bluetooth protocol. This results in a significant delay when playing audio in the entire pair of Bluetooth headphones.

[0003] For example, BLE Audio introduces the concepts of SDU (Service Data Unit) synchronization reference and presentation delay to synchronize the playback time points of different headphones in the BLE Audio network. However, this algorithm will work with the weakest device, which may waste the performance of headphones with better hardware in the network. At the same time, this algorithm configures the headphone parameters when the BLE Audio network is established and does not support the function of dynamically adjusting the headphone parameters.

[0004] Therefore, a new audio system control method and audio system are needed to improve this problem. [Summary of the Invention]

[0005] One objective of this invention is to provide an audio system control method that allows different audio playback devices to synchronize in a less restricted manner.

[0006] Another object of the present invention is to provide an audio system that allows different audio playback devices to synchronize in a less restricted manner.

[0007] One embodiment of the present invention discloses an audio system control method used in an audio system including a first audio playback device and a second audio playback device, comprising: (a) establishing an OOB (out-of-band) wireless communication channel between the first audio playback device and the second audio playback device; (b) when the first audio playback device receives audio data output from an audio source device and is ready to play the audio data, calculating a first time difference between a current time point and a first expected playback time point; (c) if the current time point is before the first expected playback time point, the first audio playback device transmits a preparation notification representing that the first audio playback device is in a ready state to the second audio playback device through the OOB wireless communication channel; (d) If the second audio playback device has received the preparation notification and received the audio data output by the audio source device and is ready to play the audio data, then it transmits a start playback notification to the first audio playback device through the OOB wireless communication channel to notify the first audio playback device that it can start playing; and (e) after the first audio playback device receives the start playback notification, the first audio playback device and the second audio playback device start playing the audio data.

[0008] Another embodiment of the present invention discloses an audio system control method used in an audio system comprising a plurality of audio playback devices, comprising: (a) establishing a wireless communication channel between the audio source device and the audio playback devices respectively; (b) when the audio playback devices receive first audio data output by an audio source device and are ready to play the first audio data, the audio playback devices respectively transmit a ready notification that the audio playback devices are in a ready state to the audio source device through the wireless communication channel; and (c) when the audio source device confirms that all the audio playback devices are in the ready state, it generates a control command to the audio playback devices to cause the audio playback devices to start playing the first audio data.

[0009] Another embodiment of the present invention discloses an audio system, including a first audio playback device and a second audio playback device. The first audio playback device establishes an OOB wireless communication channel with the second audio playback device. When the first audio playback device receives audio data output from an audio source device and is ready to play the audio data, it calculates a first time difference between a current time point and a first expected playback time point. If the current time point is before the first expected playback time point, the first audio playback device transmits a preparation notification, indicating that it is in a ready state, to the second audio playback device through the OOB wireless communication channel. If the second audio playback device has received the preparation notification and has received the audio data output from the audio source device and is ready to play the audio data, it transmits a start playback notification to the first audio playback device through the OOB wireless communication channel to notify the first audio playback device that playback can begin. After receiving the start playback notification, both the first and second audio playback devices begin playing the audio data.

[0010] According to the foregoing embodiments, the synchronization of different Bluetooth headsets can be made not limited by the presentation delay in the Bluetooth specification, which can improve the problem in the prior art that the performance of all Bluetooth headsets is limited by Bluetooth headsets with lower performance.

Implementation Method

[0012] The present invention will now be described with reference to several embodiments. It should be noted that the elements in each embodiment may be implemented using hardware (e.g., a device or circuit) or firmware (e.g., at least one program written in a microprocessor). Furthermore, the terms "first," "second," and similar descriptions in the following description are used only to define different elements, parameters, data, signals, or steps, and are not intended to limit their order. For example, the first device and the second device may be devices with the same structure but different from each other.

[0013] Figure 1 illustrates a schematic diagram of an audio system control method according to an embodiment of the present invention. As shown in Figure 1, the audio system includes a first audio playback device EP_1 and a second audio playback device EP_2. The first audio playback device EP_1 and the second audio playback device EP_2 can receive audio data from an audio source device M. In one embodiment, the audio source device M is a mobile device (e.g., a mobile phone), and the first audio playback device EP_1 and the second audio playback device EP_2 are Bluetooth headsets. In one embodiment, the audio source device and the audio playback device in the present invention use the Bluetooth protocol BLE Audio. However, it should be noted that the audio source device and the audio playback device in the present invention can be replaced by other electronic devices and are not limited to mobile devices and wireless headsets and can follow other protocols.

[0014] In the embodiment shown in Figure 1, an OOB (Out Of Band) wireless communication channel CH_O is established between the first audio playback device EP_1 and the second audio playback device EP_2. In one embodiment, the OOB wireless communication channel CH_O is a channel using non-Bluetooth technology, such as the 5G OOB channel in Wi-Fi technology. The advantage of using 5G technology is that moisture does not strongly shield or interfere with 5G. Because the main component of the human body is water, human interference is relatively large for wireless headphones; using 5G OOB can avoid human interference.

[0015] Wireless communication channels CH_1 and CH_2 will also be established between the first audio playback device EP_1, the second audio playback device EP_2, and the audio source device M, respectively. Since the first audio playback device EP_1 and the second audio playback device EP_2 are Bluetooth headphones, the wireless communication channels CH_1 and CH_2 are wireless communication channels conforming to the Bluetooth protocol. That is to say, in one embodiment, the wireless communication channels CH_1 and CH_2 can use wireless communication channels following a first protocol, while the OOB wireless communication channel CH_O can use wireless communication channels following a second protocol. The first protocol and the second protocol are different.

[0016] After establishing the OOB wireless communication channel CH_O, when the first audio playback device EP_1 receives the audio data output by the audio source device M and is ready to play the audio data, it calculates a first time difference between a current time point and a first expected playback time point. If the current time point is before the first expected playback time point (that is, before the time when audio needs to be played), the first audio playback device EP_1 transmits a preparation notification indicating that the first audio playback device EP_1 is in a ready state to the second audio playback device EP_2 through the OOB wireless communication channel CH_O. In one embodiment, the first audio playback device EP_1 calculates the first expected playback time point based on the current time point and a presentation delay specified in the Basic Audio Profile in the Bluetooth protocol. In this case, the first expected playback time point can also be called the render point.

[0017] Figure 2 illustrates a presentation delay. As shown in Figure 2, in the Bluetooth protocol, the timing of the first audio playback device EP_1 and the second audio playback device EP_2 receiving audio data is synchronized, for example, receiving audio data at an audio synchronization reference point. The audio data can be in the form of SDU. Since the first audio playback device EP_1 and the second audio playback device EP_2 decode and process the audio data (e.g., resampling or equalization) after receiving the audio data, a delay is required between the presentation point and the audio synchronization reference point. In the basic audio specification, a presentation delay is determined based on the performance of the first audio playback device EP_1 and the second audio playback device EP_2, allowing the first audio playback device EP_1 and the second audio playback device EP_2 to process the audio data and synchronize the presentation points. As mentioned earlier, the rendering latency must be matched with the performance of all audio playback devices. Therefore, if at least one of the audio playback devices has lower performance, the overall rendering latency will be set to be longer, which will limit the performance of the more powerful audio playback devices.

[0018] Please return to Figure 1. If the second audio playback device EP_2 has received a preparation notification indicating that the first audio playback device EP_1 is in a ready state, and has received the audio data output by the audio source device M and is ready to play the audio data, then it transmits a start playback notification through the OOB wireless communication channel CH_O to notify the first audio playback device EP_1 that it can start playing. After receiving the start playback notification, both the first audio playback device EP_1 and the second audio playback device EP_2 begin playing the audio data. This process can be called synchronization of the audio playback devices.

[0019] In one embodiment, if the first audio playback device EP_1 detects that the first time difference is less than a critical difference while waiting for notification from other audio playback devices to start playing, then the first audio playback device EP_1 starts playing audio data. If the critical difference is zero, it means that the current time point has reached the first expected playback time point, and then the first audio playback device EP_1 no longer waits for the second audio playback device EP_2 and starts playing audio data. In another embodiment, after the first audio playback device EP_1 and the second audio playback device EP_2 start playing audio data, the first audio playback device EP_1 or the second audio playback device EP_2 continuously calculates an actual playback time point and a second expected playback time point of the audio data, and if the number of times the actual playback time point lags behind the second expected playback time point is greater than a critical number, then the aforementioned synchronization step is performed again to adjust the time point at which the first audio playback device EP_1 and the second audio playback device EP_2 start playing audio data. In one embodiment, the second expected playback time point is also calculated based on the presentation delay specified in the basic audio specification.

[0020] The embodiment in Figure 1 is illustrated using two audio playback devices; however, the concept of the present invention can also be applied to two or more audio playback devices. Figure 3 illustrates a schematic diagram of an audio system control method according to another embodiment of the present invention. As shown in Figure 3, the audio system further includes at least one third audio playback device EP_a, EP_b…EP_x in addition to the first audio playback device EP_1 and the second audio playback device EP_2. The audio playback devices can communicate with each other through the aforementioned OOB wireless communication channel CH_O. Therefore, in the embodiment of Figure 3, each audio playback device EP_1 can transmit a readiness notification to the other audio devices through the OOB wireless communication channel CH_O (this action can also be called broadcasting). In one embodiment, the second audio playback device is the last among all the audio playback devices in the audio system to enter the readiness state. That is, in the embodiment of Figure 3, the audio playback device that enters the readiness state last notifies the other audio playback devices to start playing audio data, while the other audio playback devices do not notify the other audio playback devices to start playing audio data.

[0021] Figures 4A and 4B illustrate detailed flowcharts of the operation of the audio system shown in Figures 1 and 2 according to an embodiment of the present invention. Please refer to Figures 4A and 4B together to understand the content of the present invention. However, please note that Figures 4A and 4B are illustrated using 5G networks and Bluetooth devices as examples, but are not intended to limit the scope of the present invention.

[0022] Figures 4A and 4B include the following steps.

[0023] Step 401

[0024] The audio playback device begins to operate.

[0025] Step 403

[0026] Confirm whether there are other audio playback devices that can use the setting mechanism of the present invention. For example, confirm whether there are other audio playback devices that include an IC (Integrated Circuit) designed to execute the present invention.

[0027] If not, an OOB wireless communication channel cannot be established between audio playback devices, so proceed to step 407.

[0028] If yes, proceed to step 405.

[0029] Step 405

[0030] Establish a 5G OOB channel between audio playback devices.

[0031] Step 407

[0032] Calculate the performance points based on the presentation delay.

[0033] Step 409

[0034] Audio data received?

[0035] If yes, proceed to the next step 411; otherwise, stay at step 409 to continue confirming whether audio data has been received.

[0036] As mentioned above, the audio data may be in SDU format.

[0037] Step 411

[0038] Decode audio data.

[0039] Step 413

[0040] Processing audio data.

[0041] For example, it could be resampled or equalized audio data.

[0042] Step 415

[0043] Has the time for the performance point arrived?

[0044] If yes, proceed to the next step 417; otherwise, proceed to step 429.

[0045] Step 417

[0046] Does a 5G OOB channel exist?

[0047] If yes, otherwise return to step 415; if yes, go to step 419.

[0048] Step 419

[0049] Are other audio playback devices already in standby mode?

[0050] If yes, proceed to step 421; otherwise, proceed to step 429.

[0051] Step 421

[0052] Various audio playback devices successively transmit confirmation notifications through the 5G OOB channel.

[0053] Step 423

[0054] Continuously monitor 5G OOB channels and performance points.

[0055] Step 424

[0056] Notify other audio devices to start playing audio data.

[0057] Step 425

[0058] Has the time for performance reached its point?

[0059] If yes, otherwise return to step 423; if yes, go to step 427.

[0060] Step 427

[0061] An audio playback device has entered playback mode?

[0062] If yes, proceed to step 429; otherwise, proceed to step 423.

[0063] Step 429

[0064] Each audio playback device is in playback mode.

[0065] Step 431

[0066] Each audio playback device is in playback mode.

[0067] Steps 431 to 439 are steps to resynchronize the audio playback device after it enters playback mode. Steps 431 and 429 can be considered as the same step.

[0068] Step 433

[0069] The actual playback time lags behind the performance time (one example of the aforementioned second expected playback time)?

[0070] If yes, otherwise return to step 433; if yes, proceed to step 435.

[0071] Step 435

[0072] The cumulative number of times the team fell behind.

[0073] Step 437

[0074] The number of times lagging behind is greater than a critical number?

[0075] If yes, proceed to step 439; otherwise, return to step 435.

[0076] Step 439

[0077] Restart the synchronization process and return to step 409.

[0078] According to the foregoing embodiments, a simplified audio system control method can be obtained. Figure 5 illustrates an audio system control method according to an embodiment of the present invention, which is used in an audio system (e.g., the audio system shown in Figure 1) including a first audio playback device and a second audio playback device. The flowchart shown in Figure 5 includes the following steps:

[0079] Step 501

[0080] An OOB wireless communication channel (e.g., OOB wireless communication channel CH_O) is established between the first audio playback device and the second audio playback device. This step can be performed by the first audio playback device.

[0081] Step 503

[0082] When the first audio playback device receives audio data output by an audio source device and is ready to play the audio data, it calculates a first time difference between a current time point and a first expected playback time point.

[0083] Step 505

[0084] If the current time is before the first expected playback time, the first audio playback device will transmit a ready notification, indicating that the first audio playback device is in a ready state, to the second audio playback device through the OOB wireless communication channel.

[0085] Step 507

[0086] If the second audio playback device has received the preparation notification and received the audio data output by the audio source device and is ready to play the audio data, it transmits a start playback notification to the first audio playback device through the OOB wireless communication channel to notify the first audio playback device that it can start playing.

[0087] Step 509

[0088] After receiving the start playback notification, the first audio playback device and the second audio playback device begin playing audio data.

[0089] In one embodiment, after the first audio playback device and the second audio playback device start playing audio data, the first audio playback device or the second audio playback device continuously calculates an actual playback time point and a second expected playback time point of the audio data, and if the number of times the actual playback time point lags behind the second expected playback time point is greater than a critical number, then steps 503 to 509 are executed again.

[0090] In one embodiment, the audio system further includes at least one third audio playback device (e.g., the third audio playback devices EP_a, EP_b, etc. in the embodiment of Figure 3) in addition to the first and second audio playback devices. In this case, step 507 further transmits a preparation notification to the third audio playback device, wherein the second audio playback device is the last among all the audio playback devices in the audio system to enter the preparation state.

[0091] In the foregoing embodiments, an OOB wireless communication channel is established between the audio playback devices. However, synchronization of the audio playback devices can also be performed even when there is no OOB wireless communication channel between them. Figure 6 illustrates a schematic diagram of an audio system control method according to another embodiment of the present invention. As shown in Figure 6, the audio system includes a first audio playback device EP_1 and a second audio playback device EP_2. The first audio playback device EP_1 and the second audio playback device EP_2 can receive audio data from an audio source device M. In one embodiment, the audio source device M is a mobile device (e.g., a mobile phone), and the first audio playback device EP_1 and the second audio playback device EP_2 are Bluetooth headsets.

[0092] In the embodiment shown in Figure 6, the first audio playback device EP_1 and the second audio playback device EP_2 do not establish an OOB wireless communication channel CH_O as shown in Figure 1. Instead, wireless communication channels CH_1 and CH_2 are established between the first audio playback device EP_1, the second audio playback device EP_2, and the audio source device M, respectively. In one embodiment, wireless communication channels CH_1 and CH_2 are 5G OOB channels. If the first audio playback device EP_1 and the second audio playback device EP_2 are Bluetooth devices, then wireless communication channels CH_1 and CH_2 can also be wireless communication channels conforming to the Bluetooth protocol. In the embodiment shown in Figure 6, the playback actions of the first audio playback device EP_1 and the second audio playback device EP_2 are controlled by the audio source device M. In detail, when the first audio playback device EP_1 and the second audio playback device EP_2 receive the first audio data output by the audio source device M and are ready to play the first audio data, the first audio playback device EP_1 and the second audio playback device EP_2 respectively transmit a ready notification to the audio source device M through wireless communication channels CH_1 and CH_2. When the audio source device M confirms that all audio playback devices are in the ready state, it generates a control command to the audio playback devices to start playing the first audio data.

[0093] After the first audio playback device EP_1 and the second audio playback device EP_2 start playing the audio data, the audio source device M will collect a plurality of actual playback times of the first audio playback device EP_1 and the second audio playback device EP_2 actually playing the second audio data, and calculate the time difference of the plurality of actual playback times. If the largest of the time differences is greater than a critical difference, then the synchronization of the audio playback devices will be performed again.

[0094] Figure 7 illustrates a detailed flowchart of the operation of the audio system shown in Figure 6 according to an embodiment of the present invention. However, please note that Figure 7 is illustrated using 5G networks and Bluetooth devices as examples, but is not intended to limit the scope of the present invention.

[0095] Figure 7 includes the following steps.

[0096] Step 701

[0097] The sound source device begins to operate.

[0098] Step 703

[0099] Confirm whether there are other audio playback devices that can use the setting mechanism of the present invention. For example, confirm whether there are other audio playback devices that include an IC designed to execute the present invention.

[0100] If not, the mechanism of the present invention cannot be used between the audio source device and the audio playback device, and therefore execution can be stopped.

[0101] If yes, proceed to step 705.

[0102] Step 705

[0103] Establish a 5G OOB channel between the audio source device and the audio playback device.

[0104] Step 707

[0105] All audio playback devices have received a readiness notification?

[0106] If yes, proceed to step 709; otherwise, stay at step 707 and continue waiting.

[0107] Step 709

[0108] The audio source device generates a control command to the audio playback device through the 5G OOB channel, causing the audio playback device to start playing audio data.

[0109] Step 711

[0110] The audio source device collects multiple actual playback times of the second audio data actually played by the audio playback device.

[0111] Step 713

[0112] Determine if the largest of the time differences is greater than a critical difference.

[0113] If yes, proceed to step 715; otherwise, return to step 711.

[0114] Step 715

[0115] Perform synchronization of the audio playback device again.

[0116] Based on the embodiments in Figures 6 and 7, a summary flowchart of one of the audio system control methods provided by the present invention can be obtained. Figure 8 illustrates a summary flowchart of the operation of the audio system shown in Figure 6 according to an embodiment of the present invention, which is used in an audio system comprising a plurality of audio playback devices (e.g., the audio system shown in Figure 6). The flowchart shown in Figure 8 includes the following steps:

[0117] Step 801

[0118] Establish a wireless communication channel (e.g., wireless communication channels CH_1 and CH_2) between the audio source device and the audio playback device.

[0119] Step 803

[0120] When the audio playback device receives the first audio data output by an audio source device and is ready to play the first audio data, the audio playback device transmits a ready notification that the audio playback device is in a ready state to the audio source device through a wireless communication channel.

[0121] Step 805

[0122] When the audio source device confirms that all audio playback devices are in the ready state, it generates a control command to the audio playback device to cause the audio playback device to start playing the first audio data.

[0123] In one embodiment, after the audio playback device starts playing audio data, it collects the actual playback time of the second audio data and calculates the time difference between the actual playback times. If the largest of the time differences is greater than a critical difference, then steps 803 and 805 are executed again, that is, the synchronization of the audio playback device is performed again. According to the foregoing embodiment, the synchronization of different Bluetooth headphones can be made not limited by the presentation delay in the Bluetooth specification, which can improve the problem in the prior art that the performance of all Bluetooth headphones is limited by the Bluetooth headphones with lower performance. The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention. [Simplified Explanation of the Diagram]

[0011] Figure 1 illustrates a schematic diagram of an audio system control method according to an embodiment of the present invention. Figure 2 illustrates a schematic diagram of presentation delay. Figure 3 illustrates a schematic diagram of an audio system control method according to another embodiment of the present invention. Figures 4A and 4B illustrate detailed flowcharts of the operation of the audio system shown in Figures 1 and 2 according to an embodiment of the present invention. Figure 5 illustrates an audio system control method according to an embodiment of the present invention. Figure 6 illustrates a schematic diagram of an audio system control method according to another embodiment of the present invention. Figure 7 illustrates a detailed flowchart of the operation of the audio system shown in Figure 6 according to an embodiment of the present invention. Figure 8 illustrates an audio system control method according to another embodiment of the present invention.

Claims

1. An audio system control method, used in an audio system including a first audio playback device and a second audio playback device, comprising: step (a) establishing an OOB (out-of-band) wireless communication channel between the first audio playback device and the second audio playback device; step (b) when the first audio playback device receives audio data output from an audio source device and is ready to play the audio data, calculating a first time difference between a current time point and a first expected playback time point; step (c) if the current time point is before the first expected playback time point, the first audio playback device transmits a ready notification representing that the first audio playback device is in a ready state to the second audio playback device through the OOB wireless communication channel; step (d) If the second audio playback device has received the preparation notification and received the audio data output by the audio source device and is ready to play the audio data, it transmits a start playback notification to the first audio playback device through the OOB wireless communication channel to notify the first audio playback device that it can start playing; and (e) after the first audio playback device receives the start playback notification, the first audio playback device and the second audio playback device start playing the audio data; wherein after the first audio playback device and the second audio playback device start playing the audio data, the first audio playback device or the second audio playback device continuously calculates an actual playback time point and a second expected playback time point of the audio data, and if the number of times the actual playback time point lags behind the second expected playback time point is greater than a critical number, then step (b), step (c), step (d), and step (e) are executed again.

2. The audio system control method as described in claim 1, wherein the OOB wireless communication channel is a 5G OOB channel.

3. The audio system control method as claimed in claim 1, wherein the first audio playback device and the second audio playback device are Bluetooth devices, and step (b) calculates the first expected playback time based on the current time and a presentation delay specified in the Basic Audio Profile.

4. The audio system control method as claimed in claim 1, wherein the audio system further includes at least one third audio playback device in addition to the first audio playback device and the second audio playback device, and step (c) further transmits the preparation notification to the third audio playback device, wherein the second audio playback device is the last among all the audio playback devices in the audio system to enter the preparation state.

5. The audio system control method as claimed in claim 1, wherein if the first audio playback device detects that the first time difference is less than a critical difference while waiting for the start playback notification, the first audio playback device starts playing the audio data.

6. An audio system control method, used in an audio system comprising a plurality of audio playback devices, comprising: step (a) establishing a wireless communication channel between an audio source device and the audio playback devices respectively; step (b) when the audio playback devices receive first audio data output by the audio source device and are ready to play the first audio data, the audio playback devices respectively transmit a ready notification that they are in a ready state to the audio source device through the wireless communication channel; and step (c) when the audio source device confirms that all the audio playback devices are in the ready state, it generates a control command to the audio playback devices to cause the audio playback devices to start playing the first audio data; wherein after the audio playback devices start playing the audio data, the actual playback time of the second audio data played by the audio playback devices is collected, and the time difference of the actual playback time is calculated; if the largest of the time differences is greater than a critical difference, then step (b) and step (c) are executed again.

7. The audio system control method as described in claim 6, wherein the wireless communication channel is a 5G OOB (out of band) channel.

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