Method and apparatus for adjusting audio volume in wired / wireless multi-channel audio speaker environment

Abstract

A method performed by a source, according to one embodiment of the present specification, comprises the steps of: connecting to speakers related to a surround sound system; and transmitting, to each speaker, information related to a volume control procedure. On the basis that the volume control procedure is related to source gain adjustment, volume control of each speaker is locked, on the basis of the information, to a common maximum SPL output, and volumes of all audio data are adjusted in a PCM domain of the source prior to audio encoding and transmission.

Description

Method and device for controlling audio volume in a wired / wireless multi-channel audio speaker environment

[0001] This disclosure relates to a method and device for controlling audio volume in a wired / wireless multi-channel audio speaker environment.

[0002] With the growing demand for immersive content consumption environments, interest in multichannel audio systems that deliver three-dimensional playback in user-centric spaces is growing. However, conventional Bluetooth-based audio systems are primarily limited to two-channel stereo output (left and right), posing structural limitations in implementing spatial audio (surround sound) using multiple wireless speakers. In particular, despite the popularization of portable Bluetooth speakers, the technology for integrating them with home TVs or set-top boxes to create a stable, low-latency multichannel audio environment remains inadequate.

[0003] Meanwhile, in a multi-channel audio speaker environment, volume synchronization between speakers can sometimes be out of sync. For example, if the SPL (Sound Pressure Level) value for each speaker is different, the volume value will vary with each volume adjustment step, and even if the volume is changed in the same step, the volume synchronization between the speakers will be out of sync. For example, if the SPL value for each speaker is known from the source, and the volume is changed in the same step, the volume synchronization between the speakers will be out of sync.

[0004] The purpose of this specification is to provide a method for solving the above-described problems.

[0005] The technical problems to be achieved in this specification are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which this specification pertains from the description below.

[0006] According to one embodiment of the present disclosure for solving the above-described problem, a method performed by a source comprises the steps of connecting speakers associated with a surround sound system and transmitting information related to a volume control procedure to each speaker. Based on the information that the volume control procedure is related to source gain adjustment, the volume control of each speaker is locked to a common maximum Sound Pressure Level (SPL, output), and the volume of all audio data in the Pulse Code Modulation (PCM) domain of the source is adjusted before audio encoding and transmission. Accordingly, volume synchronization between speakers can be effectively achieved in a multi-channel audio speaker environment.

[0007] According to embodiments of the present disclosure, the volume is controlled at the source based on the common maximum SPL output. Therefore, the volume of speakers can be effectively synchronized in a multi-channel audio environment even if the SPL values ​​of each speaker are not known.

[0008] According to embodiments of the present disclosure, audio data (e.g., Broadcast Isochronous Stream, BIS) is transmitted to each speaker along with volume control data based on the volume control procedure related to speaker gain adjustment. Therefore, if the source knows the SPL value of each speaker, individual volume adjustments for each speaker can be made to synchronize the volume at the listener's position.

[0009] The accompanying drawings are intended to aid understanding of the present specification and may provide embodiments of the present specification along with detailed descriptions. However, the technical features of the present specification are not limited to specific drawings, and the features disclosed in each drawing may be combined with each other to form new embodiments. Reference numerals in each drawing may indicate structural elements.

[0010] Figure 1 is a schematic diagram showing an example of a wireless communication system using the Bluetooth low energy technology proposed in this specification.

[0011] FIG. 2 shows an example of an internal block diagram of a device capable of implementing the methods proposed in this specification.

[0012] Figure 3 shows an example of a Bluetooth communication architecture to which the methods proposed in this specification can be applied.

[0013] Figure 4 shows an example of the structure of the GATT (Generic Attribute Profile) of Bluetooth low energy.

[0014] FIG. 5 is a flowchart illustrating an example of a connection procedure method in Bluetooth low energy technology to which various embodiments of the present specification can be applied.

[0015] FIG. 6 illustrates an example of a system structure in which multi-channel audio signals are transmitted between a BLE-based TV transmitting device and multiple BLE audio receiving speakers.

[0016] FIG. 7 illustrates an example of a compensation procedure for synchronizing image processing delay and audio processing delay in a Bluetooth low-latency audio system proposed in this specification.

[0017] FIG. 8 illustrates an example of a test stream-based calibration procedure for measuring and adjusting the sound pressure level of each speaker based on a user position in a BLE-based audio system proposed in this specification.

[0018] FIG. 9 illustrates an example of an inter-speaker synchronization correction structure for correcting sound synchronization error due to a difference in distance between a TV speaker and a rear speaker in a multi-channel audio system proposed in this specification.

[0019] FIG. 10 illustrates an example of a speaker-to-speaker synchronization structure for compensating for sound synchronization errors due to distance differences between rear speakers in a multi-channel audio system proposed in this specification.

[0020] FIG. 11 illustrates an example of an overall system configuration for multi-channel audio transmission between a BLE-based TV and multiple audio receiving devices proposed in this specification and a profile structure based on Surround Sound Audio Profile (SSAP).

[0021] FIG. 12 is a diagram illustrating a link related to initial volume setting in a multi-channel audio environment proposed in this specification.

[0022] FIG. 13 is a diagram illustrating channels related to volume control during playback in a multi-channel audio environment proposed in this specification.

[0023] FIG. 14 is a diagram illustrating an initial volume setting related to source gain control according to one embodiment of the present specification.

[0024] FIG. 15 is a diagram illustrating volume control during playback in connection with source gain control according to one embodiment of the present specification.

[0025] FIG. 16 is a diagram illustrating a state in which the volume of speakers is controlled based on source gain control according to one embodiment of the present specification.

[0026] FIG. 17 is a diagram illustrating an initial volume setting related to speaker gain control according to another embodiment of the present specification.

[0027] FIG. 18 is a diagram illustrating volume control during playback in connection with speaker gain control according to another embodiment of the present specification.

[0028] FIG. 19 is a diagram illustrating a state in which the volume of speakers is controlled based on speaker gain control according to another embodiment of the present specification.

[0029] FIG. 20 is a diagram illustrating volume control of four speakers within a Broadcast Isochronous Group (BIG) based on speaker gain control according to another embodiment of the present specification.

[0030] FIG. 21 is a diagram illustrating an operation of adjusting the volume of speakers using periodic BLE broadcast and response according to another embodiment of the present specification.

[0031] FIG. 22 is a flowchart illustrating a method performed by a source according to one embodiment of the present specification.

[0032] FIG. 23 is a flowchart illustrating a method performed by a speaker according to another embodiment of the present specification.

[0033] In various embodiments of this specification, “A or B” can mean “only A,” “only B,” or “both A and B.” In other words, in various embodiments of this specification, “A or B” can be interpreted as “A and / or B.” For example, in various embodiments of this specification, “A, B or C” can mean “only A,” “only B,” “only C,” or “any combination of A, B and C.”

[0034] In various embodiments of this specification, a slash ( / ) or a comma may mean "and / or." For example, "A / B" may mean "A and / or B." Accordingly, "A / B" may mean "only A," "only B," or "both A and B." For example, "A, B, C" may mean "A, B, or C."

[0035] In various embodiments of the present specification, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Furthermore, in various embodiments of the present specification, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted as equivalent to “at least one of A and B.”

[0036] Additionally, in various embodiments of the present specification, “at least one of A, B and C” can mean “only A,” “only B,” “only C,” or “any combination of A, B and C.” Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C.”

[0037] Figure 1 is a schematic diagram showing an example of a wireless communication system using the Bluetooth low energy technology proposed in this specification.

[0038] A wireless communication system (100) includes at least one server device (Server Device, 120) and at least one client device (Client Device, 110).

[0039] The server device and client device perform Bluetooth communication using Bluetooth Low Energy (BLE, hereinafter referred to as 'BLE' for convenience) technology.

[0040] First, BLE technology has a relatively small duty cycle compared to Bluetooth BR / EDR (Basic Rate / Enhanced Data Rate) technology, allows for low-cost production, and significantly reduces power consumption through low-speed data transmission rates, enabling operation for more than a year using a coin cell battery.

[0041] Additionally, BLE technology simplifies the connection process between devices and is designed to have a smaller packet size compared to Bluetooth BR / EDR technology.

[0042] In BLE technology, (1) the number of RF channels is 40, (2) the data transmission speed supports 1 Mbps, (3) the topology is a scatternet structure, (4) the latency is 3 ms, (5) the maximum current is 15 mA or less, (6) the output power is 10 mW (10 dBm) or less, and (7) it is mainly used in applications such as mobile phones, watches, sports, healthcare, sensors, and device control.

[0043] The server device (120) can operate as a client device in a relationship with other devices, and the client device can operate as a server device in a relationship with other devices. That is, in a BLE communication system, any one device can operate as a server device or a client device, and, if necessary, can operate as a server device and a client device simultaneously.

[0044] The above server device (120) may be expressed as a data service device, a client device, a slave device, a server, a conductor, a host device, a gateway, a sensing device, a monitoring device, a first device, a second device, etc.

[0045] The above client device (110) can be expressed as a server device (master device), a master, a client, a member, a sensor device, a sink device, a collector, a third device, a fourth device, etc.

[0046] The server device and the client device are the main components of the wireless communication system, and the wireless communication system may include other components in addition to the server device and the client device.

[0047] The above server device refers to a device that receives data from a client device and performs direct communication with the client device, thereby providing data to the client device through a response when receiving a data request from the client device.

[0048] Additionally, the server device sends a notification message and an indication message to the client device to provide data information to the client device. Additionally, when the server device transmits an indication message to the client device, it receives a confirmation message corresponding to the indication message from the client.

[0049] In addition, the server device can provide data information to a user through an output unit (Display Unit) or receive a request input from a user through an input unit (User Input Interface) in the process of transmitting and receiving notifications, instructions, and confirmation messages to and from a client device.

[0050] Additionally, the server device can read data from a memory unit or write new data to the memory unit during the process of transmitting and receiving messages with the client device.

[0051] Additionally, one server device can be connected to multiple client devices, and can easily reconnect (or connect) to the client devices by utilizing bonding information.

[0052] The above client device (120) refers to a device that requests data information and data transmission from a server device.

[0053] The client device receives data from the server device through a notification message, an instruction message, etc., and when receiving an instruction message from the server device, sends a confirmation message in response to the instruction message.

[0054] Likewise, the client device can provide information to the user through an output unit or receive input from the user through an input unit during the process of transmitting and receiving messages with the server device.

[0055] Additionally, the client device can read data from memory or write new data to the memory during the process of transmitting and receiving messages with the server device.

[0056] Hardware components such as the output section, input section, and memory of the above server device and client device will be examined in detail in Fig. 2.

[0057] Additionally, the wireless communication system can establish a Personal Area Network (PAN) via Bluetooth technology. For example, the wireless communication system can establish a private piconet between devices, enabling the quick and secure exchange of files, documents, and other information.

[0058] FIG. 2 shows an example of an internal block diagram of a device capable of implementing the methods proposed in this specification.

[0059] As illustrated in FIG. 2, the server device (110) includes an input unit (User Input Interface, 112), a power supply unit (Power Supply Unit, 113), a control unit (Control Unit, 114), a memory unit (Memory Unit, 115), a network interface (Network Interface, 116) including a Bluetooth interface, storage (Storage, 117), an output unit (Display Unit, 118), and a multimedia module (Multi Media Module, 119).

[0060] The input unit (User Input Interface, 112), power supply unit (Power Supply Unit, 113), control unit (Control Unit, 114), memory (Memory Unit, 115), network interface (Network Interface, 116) including Bluetooth interface, storage (Storage, 117), output unit (Display Unit, 118), and multimedia module (Multi media Module, 119) are functionally interconnected to perform the method proposed in this specification.

[0061] In addition, as illustrated in FIG. 2, the client devices (#1 and #2) (120) include an input unit (User Input Interface, 122), a power supply unit (Power Supply Unit, 123), a control unit (Control Unit, 124), a memory unit (Memory Unit, 125), a network interface (Network Interface, 126) including a Bluetooth interface, storage (Storage, 127), an output unit (Display Unit, 128), and a multimedia module (Multi media Module, 129).

[0062] The above input unit (User Input Interface, 122), power supply unit (Power Supply Unit, 123), control unit (Control Unit, 124), memory (Memory Unit, 125), network interface (Network Interface, 126) including Bluetooth interface, storage (Storage, 127), output unit (Display Unit, 128), and multimedia module (Multi media Module, 129) are functionally interconnected to perform the method proposed in this specification.

[0063] The above network interface (116, 126) refers to a unit (or module) capable of transmitting request / response, command, notification, instruction / confirmation messages, etc. or data between devices using Bluetooth technology.

[0064] The above memory (115, 125) is a unit implemented in various types of devices, and refers to a unit in which various types of data are stored. In addition, the storage (117, 127) refers to a unit that performs a function similar to memory.

[0065] The above control unit (114, 124) refers to a module that controls the overall operation of the server device (110) or client device (120), and controls to request transmission of a message to a network interface or to process a received message.

[0066] The above control unit (114, 124) may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device.

[0067] The above memory (115, 125) may include a ROM (read-only memory), a RAM (random access memory), a flash memory, a memory card, a storage medium, and / or other storage devices.

[0068] The above memory (115, 125) may be internal or external to the processor (114, 124) and may be connected to the processor (114, 124) by various well-known means.

[0069] The above output unit (118, 128) refers to a module for providing device status information and message exchange information to the user through a screen.

[0070] The above power supply unit (power supply unit, 113, 123) refers to a module that receives external power and internal power under the control of the control unit and supplies the power required for the operation of each component.

[0071] As discussed above, BLE technology has a small duty cycle and can significantly reduce power consumption through low data rates.

[0072] Figure 3 shows an example of a Bluetooth communication architecture to which the methods proposed in this specification can be applied.

[0073] Specifically, FIG. 3 shows an example of the architecture of Bluetooth LE (Low Energy).

[0074] As illustrated in FIG. 3, the BLE architecture includes a controller stack (Controller stackACK) operable to handle timing-critical wireless device interfaces and a host stack (Host stackACK) operable to handle high level data.

[0075] The above Controller stack may be referred to as a Controller, but to avoid confusion with the processor, which is an internal component of the device mentioned in FIG. 2 above, it will be referred to as a Controller stackACK hereinafter.

[0076] First, the controller stack may be implemented using a communication module that may include a Bluetooth radio, and a processor module that may include a processing device, such as a microprocessor.

[0077] The host stack can be implemented as part of an OS running on a processor module, or as an instantiation of a package on top of the OS.

[0078] In some cases, the controller stack and the host stack may operate or execute on the same processing device within a processor module.

[0079] The host stack includes GAP (Generic Access Profile, 310), GATT-based Profiles (320), GATT (Generic Attribute Profile, 330), ATT (Attribute Protocol, 340), SM (Security Manager, 350), and L2CAP (Logical Link Control and Adaptation Protocol, 360). However, the host stack is not limited to this and may include various protocols and profiles.

[0080] The host stack multiplexes various protocols, profiles, etc. provided above Bluetooth using L2CAP.

[0081] First, L2CAP (Logical Link Control and Adaptation Protocol,360) provides a single bidirectional channel for transmitting data to a specific protocol or profile.

[0082] L2CAP may be capable of multiplexing data between upper layer protocols, segmenting and reassembling packages, and managing multicast data transmission.

[0083] BLE uses three fixed channels (one for signaling CH, one for Security Manager, and one for Attribute protocol).

[0084] On the other hand, BR / EDR (Basic Rate / Enhanced Data Rate) uses dynamic channels and supports protocol service multiplexer, retransmission, streaming mode, etc.

[0085] SM (Security Manager, 350) is a protocol for authenticating devices and providing key distribution.

[0086] ATT (Attribute Protocol, 340) defines the rules for accessing data from other devices in a server-client architecture. ATT has six message types: Request, Response, Command, Notification, Indication, and Confirmation.

[0087] That is, ① Request and Response messages: The Request message is a message for requesting specific information from a client device to a server device, and the Response message is a response message to the Request message, and refers to a message transmitted from the server device to the client device.

[0088] ② Command message: A message sent from a client device to a server device to instruct a specific action command. The server device does not send a response to the Command message to the client device.

[0089] ③ Notification message: A message sent from a server device to a client device for notification of events, etc.; the client device does not send a confirmation message for the Notification message to the server device.

[0090] ④ Indication and Confirm messages: Messages sent from the server device to the client device for notification of events, etc. Unlike the Notification message, the client device sends a confirmation message for the Indication message to the server device.

[0091] GAP (Generic Access Profile) is a new layer implemented for BLE technology, which is used to control role selection for communication between BLE devices and how multi-profile operation occurs.

[0092] Additionally, GAP is primarily used in device discovery, connection creation, and security procedures, defines how to provide information to users, and defines the types of attributes as follows:

[0093] ① Service: Defines the basic operation of the device through a combination of data-related behaviors.

[0094] ② Include: Defines the relationship between services

[0095] ③ Characteristics: Data values ​​used in the service

[0096] ④ Behavior: Computer-readable format defined as UUID (Universal Unique Identifier, value type)

[0097] GATT-based Profiles are profiles that depend on GATT and are primarily applied to BLE devices. GATT-based Profiles include Battery, Time, FindMe, Proximity, Time, and Object Delivery Service. The specifics of GATT-based Profiles are as follows.

[0098] Battery: How to exchange battery information

[0099] Time: A method for exchanging time information

[0100] FindMe: Distance-based alarm service

[0101] Proximity: How to Exchange Battery Information

[0102] Time: A method for exchanging time information

[0103] GATT can function as a protocol that describes how ATT is used when composing services. For example, GATT can be used to specify how ATT attributes are grouped into services, and can be used to describe the features associated with services.

[0104] Therefore, GATT and ATT can use features to describe the state and services of a device, how features relate to each other, and how they are used.

[0105] The controller stack includes a physical layer (390), a link layer (380), and a host controller interface (370).

[0106] The physical layer (wireless transmission / reception module, 390) is a layer that transmits and receives 2.4 GHz wireless signals and uses GFSK (Gaussian Frequency Shift Keying) modulation and a frequency hopping technique consisting of 40 RF channels.

[0107] The link layer (380) transmits or receives Bluetooth packets.

[0108] Additionally, the link layer performs advertising and scanning functions using three advertising channels, then creates a connection between devices, and provides the ability to send and receive data packets of up to 42 bytes through 37 data channels.

[0109] HCI (Host Controller Interface) provides an interface between the Host stack and the Controller stack, allowing the Host stack to provide commands and data to the Controller stack, and allowing the Controller stack to provide events and data to the Host stack.

[0110] Below, we will briefly look at the procedures of Bluetooth Low Energy (BLE) technology.

[0111] BLE procedures can be divided into device filtering procedures, advertising procedures, scanning procedures, discovering procedures, and connecting procedures.

[0112] Device Filtering Procedure

[0113] Device filtering procedures are a way to reduce the number of devices that respond to requests, instructions, notifications, etc. in the controller stack.

[0114] When a request is received from any device, since it is unnecessary to respond to it, the controller stack can control the power consumption of the BLE controller stack by reducing the number of requests transmitted.

[0115] An advertising device or scanning device may perform the above device filtering procedure to limit the devices that receive advertising packets, scan requests, or connection requests.

[0116] Here, an advertising device refers to a device that transmits an advertising event, i.e., performs an advertisement, and is also expressed as an advertiser.

[0117] A scanning device is a device that performs scanning and transmits scan requests.

[0118] In BLE, when a scanning device receives some advertising packets from an advertising device, the scanning device must send a scan request to the advertising device.

[0119] However, if a device filtering procedure is used to make sending scan requests unnecessary, the scanning device may ignore advertising packets transmitted from the advertising device.

[0120] Device filtering procedures may also be used during the connection request process. If device filtering is used during the connection request process, the connection request is ignored, eliminating the need to send a response to the connection request.

[0121] Advertising Procedure

[0122] An advertising device performs an advertising procedure to perform a non-directional broadcast to devices within the area.

[0123] Here, non-directional broadcast refers to broadcast in all directions rather than broadcasting in a specific direction.

[0124] In contrast, a directional broadcast refers to a broadcast in a specific direction. A non-directional broadcast occurs without a connection procedure between an advertising device and a device in a listening (or listening) state (hereinafter referred to as a listening device).

[0125] The advertising process is used to establish a Bluetooth connection with a nearby initiating device.

[0126] Alternatively, the advertising procedure may be used to provide periodic broadcasts of user data to scanning devices listening on the advertising channel.

[0127] In the advertising process, all advertisements (or advertising events) are broadcast through the advertising physical channel.

[0128] Advertising devices can receive scan requests from listening devices that are listening to obtain additional user data from the advertising device. The advertising device transmits a response to the scan request to the device that sent the scan request over the same advertising physical channel as the advertising physical channel that received the scan request.

[0129] Broadcast user data sent as part of advertising packets is dynamic data, whereas scan response data is typically static data.

[0130] An advertising device can receive a connection request from an initiating device on an advertising (broadcast) physical channel. If the advertising device uses a connectable advertising event and the initiating device is not filtered by the device filtering procedure, the advertising device stops advertising and enters connected mode. The advertising device can resume advertising after entering connected mode.

[0131] Scanning Procedure

[0132] A device performing scanning, i.e., a scanning device, performs a scanning procedure to listen for non-directional broadcasts of user data from advertising devices using an advertising physical channel.

[0133] The scanning device transmits a scan request to the advertising device via the advertising physical channel to request additional data from the advertising device. The advertising device transmits a scan response, which is a response to the scan request, including the additional data requested from the scanning device via the advertising physical channel.

[0134] The above scanning procedure can be used while connecting with other BLE devices in a BLE piconet.

[0135] If the scanning device is in initiator mode, which means that it can receive a broadcasted advertising event and initiate a connection request, the scanning device can initiate a Bluetooth connection with the advertising device by sending a connection request to the advertising device over the advertising physical channel.

[0136] When a scanning device sends a connection request to an advertising device, the scanning device stops initiator mode scanning for further broadcasts and enters connection mode.

[0137] Discovery Procedure

[0138] Devices capable of Bluetooth communication (hereinafter referred to as “Bluetooth devices”) perform advertising and scanning procedures to discover nearby devices or to be discovered by other devices within a given area.

[0139] The discovery process is performed asymmetrically. A Bluetooth device attempting to discover other devices in its vicinity is called a discovering device and listens for devices advertising scannable advertising events. A Bluetooth device discovered and available to other devices is called a discoverable device and actively broadcasts advertising events over the advertising (broadcast) physical channel to make it scannable.

[0140] Both the discovering device and the discoverable device may already be connected to other Bluetooth devices in the piconet.

[0141] Connecting Procedure

[0142] The connection procedure is asymmetric, requiring one Bluetooth device to perform an advertising procedure while another Bluetooth device performs a scanning procedure.

[0143] That is, the advertising process can be targeted, resulting in only one device responding to the advertisement. After receiving an accessible advertising event from the advertising device, a connection can be initiated by sending a connection request to the advertising device via the advertising (broadcast) physical channel.

[0144] Next, we will briefly look at the operating states in BLE technology, namely Advertising State, Scanning State, Initiating State, and Connection State.

[0145] Advertising State

[0146] The Link Layer (LL) enters the advertising state at the direction of the host (stack). When the Link Layer is in the advertising state, it transmits advertising Packet Data Units (PDUs) in advertising events.

[0147] Each advertising event consists of at least one advertising PDU, which are transmitted via the advertising channel indices used. An advertising event may terminate when each advertising PDU has been transmitted via the advertising channel indices used, or may terminate earlier if the advertising device needs to free up space for other functions.

[0148] Scanning State

[0149] The link layer enters the scanning state at the direction of the host (stack). In the scanning state, the link layer listens for advertising channel indices.

[0150] There are two types of scanning states: passive scanning and active scanning, and each scanning type is determined by the host.

[0151] No separate time or advertising channel index is defined for performing scanning.

[0152] During the scanning state, the link layer listens for advertising channel indices for the duration of the scanWindow. The scanInterval is defined as the interval between the start points of two consecutive scan windows.

[0153] The link layer must listen for the completion of all scan intervals in the scan window, as directed by the host, provided there are no scheduling conflicts. In each scan window, the link layer must scan a different advertising channel index. The link layer uses all available advertising channel indices.

[0154] In passive scanning, the link layer only receives packets and does not transmit any packets.

[0155] When actively scanning, the link layer listens to the advertising device for advertising PDUs and depending on the advertising PDU type, may request additional information about the advertising device.

[0156] Initiating State

[0157] The link layer enters the initiated state at the direction of the host (stack).

[0158] When the link layer is in the initiating state, the link layer listens for advertising channel indices.

[0159] During the initiation state, the link layer listens for advertising channel indices during the scan window period.

[0160] connection state

[0161] The link layer enters a connected state when the device performing the connection request, i.e., the initiating device, sends a CONNECT_REQ PDU to the advertising device, or when the advertising device receives a CONNECT_REQ PDU from the initiating device.

[0162] Once a connection enters the connected state, it is considered established. However, the connection need not be considered established at the time it enters the connected state. The only difference between a newly created connection and an established connection is the link-layer connection supervision timeout value.

[0163] When two devices are connected, they act in different roles.

[0164] The link layer that performs the master role is called the master, and the link layer that performs the slave role is called the slave. The master controls the timing of connection events, and connection events indicate the point in time when the master and slave are synchronized.

[0165] Below, we will briefly examine the packets defined in the Bluetooth interface. BLE devices use the packets defined below.

[0166] Packet Format

[0167] The Link Layer has only one packet format, which is used for both advertising channel packets and data channel packets.

[0168] Each packet consists of four fields: Preamble, Access Address, PDU, and CRC.

[0169] When a packet is transmitted on an advertising physical channel, the PDU will be an advertising channel PDU, and when a packet is transmitted on a data physical channel, the PDU will be a data channel PDU.

[0170] Advertising Channel PDU

[0171] Advertising channel PDUs (Packet Data Units) have a 16-bit header and payloads of various sizes.

[0172] The PDU type field of the advertising channel PDU included in the header indicates the PDU type as defined in Table 1 below.

[0173]

[0174] Advertising PDU

[0175] The advertising channel PDU types below are called advertising PDUs and are used in specific events.

[0176] ADV_IND: Connectable non-directional advertising event

[0177] ADV_DIRECT_IND: Connectable directional advertising event

[0178] ADV_NONCONN_IND: Non-directional ad event that is not reachable

[0179] ADV_SCAN_IND: Scannable non-directional ad event

[0180] The above PDUs are transmitted by the link layer in the advertising state and received by the link layer in the scanning state or initiating state.

[0181] Scanning PDU

[0182] The advertising channel PDU type below is called a scanning PDU and is used in the conditions described below.

[0183] SCAN_REQ: Sent by the link layer in scanning state and received by the link layer in advertising state.

[0184] SCAN_RSP: Sent by the link layer in advertising state and received by the link layer in scanning state.

[0185] Initiating PDU

[0186] The advertising channel PDU type below is called an initiation PDU.

[0187] CONNECT_REQ: Sent by the link layer in the initiating state and received by the link layer in the advertising state.

[0188] Data Channel PDU

[0189] A data channel PDU has a 16-bit header, a payload of variable size, and may include a Message Integrity Check (MIC) field.

[0190] The procedures, states, packet formats, etc. in BLE technology discussed above can be applied to perform the methods proposed in this specification.

[0191] Figure 4 shows an example of the structure of the GATT (Generic Attribute Profile) of Bluetooth low energy.

[0192] Referring to Figure 4, a structure for exchanging profile data of Bluetooth low energy can be examined.

[0193] Specifically, GATT (Generic Attribute Profile) defines how to exchange data using services and characteristics between Bluetooth LE devices.

[0194] Typically, a peripheral device (e.g., a sensor device) acts as a GATT server and has definitions for services and characteristics.

[0195] To read or write data, a GATT client sends a data request to a GATT server, and all operations (transactions) are initiated by the GATT client and receive responses from the GATT server.

[0196] The GATT-based operation structure used in Bluetooth LE is based on profiles, services, and characteristics, and can form a vertical structure as shown in Fig. 5.

[0197] The above profile consists of one or more services, and the services may consist of one or more characteristics or other services.

[0198] The above service serves to logically divide data into units and may include one or more characteristics or other services. Each service has a 16-bit or 128-bit identifier called a Universal Unique Identifier (UUID).

[0199] The above characteristic is the lowest unit in the GATT-based operation structure. The characteristic contains only one piece of data and, similar to the above service, has a 16-bit or 128-bit UUID.

[0200] The above characteristics are defined by the values ​​of various pieces of information, and each piece of information requires one attribute. Multiple consecutive attributes can be used for the above characteristics.

[0201] The above attribute consists of four components and has the following meanings:

[0202] - handle: address of the property

[0203] - Type: Type of property

[0204] - Value: The value of the property

[0205] - Permission: Access rights to properties

[0206] FIG. 5 is a flowchart showing an example of a connection procedure method in Bluetooth low energy technology to which the present invention can be applied.

[0207] The server transmits advertising messages to the client through three advertising channels (S5010).

[0208] A server may be called an Advertiser before connection, and a Master after connection. An example of such a server may be a sensor (e.g., a temperature sensor).

[0209] Additionally, a client may be referred to as a "Scanner" before connection and as a "Slave" after connection. An example of a client may be a smartphone.

[0210] As previously discussed, Bluetooth communicates across 40 channels over the 2.4 GHz band. Of these 40 channels, three are advertising channels, used to exchange various advertising packets and other packets used to establish a connection.

[0211] The remaining 37 channels are used for data exchange after connection as data channels.

[0212] After receiving the advertisement message, the client may send a Scan Request message to the server to obtain additional data (e.g., server device name, etc.) from the server.

[0213] In this case, the server transmits a Scan Response message containing additional data in response to a Scan Request message to the client.

[0214] Here, the Scan Request message and the Scan Response message are the end of an advertising packet, and the advertising packet can only contain user data of 31 bytes or less.

[0215] Therefore, if there is data whose size is larger than 3 bytes but the overhead is too high to send the data by establishing a connection, the data is sent in two parts using a scan request message / scan response message.

[0216] Next, the client sends a connection request message to the server to establish a Bluetooth connection with the server (S5020).

[0217] Through this, a Link Layer (LL) connection is established between the server and the client.

[0218] Afterwards, the server and client perform security establishment procedures.

[0219] The secure establishment procedure may be interpreted as or performed incorporating Secure Simple Pairing.

[0220] That is, the security establishment procedure can be carried out through Phase 1 to Phase 3.

[0221] Specifically, a pairing procedure (phase 1) is performed between the server and the client (S5030).

[0222] The pairing procedure involves the client sending a pairing request message to the server, and the server sending a pairing response message to the client.

[0223] The pairing process involves exchanging authentication requirements, input / output capabilities, and key size information between devices. This information is used to determine which key generation method to use in Phase 2.

[0224] Next, as phase 2, legacy pairing or secure connections are performed between the server and the client (S5040).

[0225] In Phase 2, a 128-bit temporary key and a short term key (STK) are generated to perform legacy pairing.

[0226] - Temporary Key: Key created to generate STK

[0227] - Short Term Key (STK): Key value used to create an encrypted connection between devices.

[0228] If a secure connection is performed in Phase 2, a 128-bit Long Term Key (LTK) is generated.

[0229] - Long Term Key (LTK): A key value used not only for encrypted connections between devices but also for future connections.

[0230] Next, as phase 3, a key distribution procedure is performed between the server and the client (S5050).

[0231] This establishes a secure connection between the server and client, forming an encrypted link to enable data transmission and reception.

[0232] Isochronous Channel General

[0233] For audio signals, you can see that audio streaming data or audio data occurs periodically at Idle Event Interval intervals.

[0234] Audio data occurs periodically (or at specific time intervals) depending on its characteristics. Here, a specific time period during which audio data occurs periodically can be expressed as an Idle Event Interval. Each audio data is transmitted during each Idle Event Interval. Furthermore, each audio data can be transmitted throughout the entire Idle Event Interval or a portion of the Idle Event Interval. When transmitting audio streaming data that occurs periodically or regularly using the BLE mechanism, advertising and scanning procedures, communication procedures, and disconnection procedures must be performed each time the generated audio data is transmitted or received. However, audio data is generally generated periodically, and regardless of the amount of data, a latency guarantee for audio data transmission is essential.

[0235] However, there is a problem that latency occurs in audio data transmission when advertising and scanning procedures, communication procedures, and disconnection procedures must be performed every time new audio data is transmitted.

[0236] Audio data transmission through hearing aids (HA) or headsets can achieve higher energy efficiency by utilizing BLE technology rather than Bluetooth BR / EDR technology because the amount of data generated is relatively small. However, as previously discussed, the Data Channel Process of BLE technology requires advertising and connection for each data transmission, which results in a large overhead in data transmission. In particular, the Latency Guarantee, which is absolutely necessary for audio data transmission, cannot be guaranteed.

[0237] In addition, since the Data Channel Process of BLE technology aims to increase energy efficiency by transmitting data that occurs sporadically only when necessary and inducing deep sleep of the BLE device in other time domains, it may be difficult to apply the Data Channel Process of BLE technology to the transmission of audio data that occurs periodically.

[0238] Definition of Isochronous Channels and Related Mechanisms

[0239] A new channel, the Isochronous Channel, is defined to transmit periodically occurring data using BLE technology.

[0240] An isochronous channel is a channel used to transmit isochronous data between devices that use isochronous streams (e.g., Conductor-Member).

[0241] Isochronous data refers to data that is transmitted periodically or regularly at specific time intervals.

[0242] That is, an isochronous channel may refer to a channel through which periodically occurring data, such as audio data or voice data, is transmitted and received in BLE technology. In addition, the isochronous channel may refer to a channel through which data generated based on a user input of a game user's controller device is transmitted and received in a gaming scenario. The isochronous channel may be used to transmit and receive data with a single member, a set of one or more coordinated members, or multiple members. In addition, the isochronous channel corresponds to a flushing channel that may be used to transmit and receive important data in an isochronous stream, such as audio streaming, or in another time domain.

[0243] Composition of various embodiments of this specification

[0244] Problems with prior art

[0245] In a multi-channel audio speaker environment, if the SPL values ​​for each speaker are different, the volume value will vary with each volume adjustment step, so even if the volume is changed in the same step, the volume between each speaker will not be synchronized. If the SPL values ​​for each speaker are known from the source device, changing the volume in the same step will cause the volume between each speaker to be out of sync.

[0246] Summary of various embodiments of this specification

[0247] This specification provides a method for fixing the volume of a speaker and adjusting the loudness of a sound from a transmitter in a multi-channel audio environment.

[0248] This specification provides a method for adjusting Broadcast Channel Volume using periodic Broadcast and Response.

[0249] This specification provides a method for adjusting the volume value for each speaker when the SPL value for each speaker is known in a multi-channel audio environment.

[0250] This specification provides a method for controlling the volume of each wireless speaker using a BLE Broadcast channel.

[0251] Effects of various embodiments of this specification

[0252] Various embodiments of this specification allow for volume synchronization of speakers even when the SPL values ​​of each speaker are unknown. If the SPL values ​​of each speaker are known, individual volume adjustments for each speaker can be made to synchronize the volume at the listener's position.

[0253] FIG. 6 illustrates an example of a system structure in which multi-channel audio signals are transmitted between a BLE-based TV transmitting device and multiple BLE audio receiving speakers.

[0254] Figure 6 illustrates an example system architecture that utilizes BLE (Bluetooth Low Energy) technology to wirelessly transmit multi-channel audio signals between a TV transmitter and multiple audio receiver speakers. The system of Figure 6 configures the TV as an audio transmitter (Initiator) and each speaker as an audio receiver (Acceptor), enabling a multi-channel audio environment without wired connections. It utilizes BLE's ISO channel, making it suitable for audio data transmission where time synchronization is critical.

[0255] The TV LE Audio Tx Device includes a video display, an audio decoder / encoder, a controller, and a BLE Tx interface. The audio decoder / encoder converts surround audio formats such as Dolby or DTS into PCM and encodes it into the LC3 codec suitable for BLE transmission. It also supports mono unicast transmission. The TV wirelessly transmits the processed audio signal to external speakers via the BLE Tx interface. Configuration information can be communicated bidirectionally, while the actual audio stream is transmitted unidirectionally.

[0256] The Speaker LE Audio Rx Device consists of a BLE Tx / Rx interface, an audio decoder, an LC3 decoder, a controller, and a speaker driver. Each speaker receives BLE audio data wirelessly transmitted from the TV through the BLE Tx / Rx interface. The received data is restored to the original audio signal through the LC3 decoder and audio decoder, and this signal is output as sound through the speaker driver. Speakers with Tx / Rx interfaces can be used for exchanging setting information with the TV or receiving control signals.

[0257] The system in Figure 6 operates by processing multichannel audio signals, such as 5.1 channels, from a TV and assigning and transmitting them to wireless speakers, either individually or in groups. Each speaker receives and plays audio data for its assigned channel, allowing users to experience a wireless surround sound system without the need for complex audio cable connections. This offers the advantage of increased installation flexibility and a cleaner user experience.

[0258] FIG. 7 illustrates an example of a compensation procedure for synchronizing image processing delay and audio processing delay in a Bluetooth low-latency audio system proposed in this specification.

[0259] Video and audio signals each have their own unique delays as they pass through various stages of decoding, processing, and output. This delay difference can cause misalignment between video and audio, making it essential to synchronize the two for a natural audiovisual experience.

[0260] The video processing path involves compressed data being decoded, then undergoing image enhancement and display output. This process can include various processes such as frame doubling, anti-aliasing, and TCON (Timing Controller), which, as shown in the diagram, can result in a relatively large delay of approximately 100 ms or more. This is the result of a combination of the physical delay required to display the image on screen and the processing delay.

[0261] The audio processing path involves decoding compressed audio data, then going through the Bluetooth encoding / transmission / decoding process, and possibly applying additional audio enhancements. This includes various audio-related processes such as buffering, pop filtering, woofer boost, and active noise cancellation. These processes introduce delays into the audio signal, and the diagram shows this audio processing delay at approximately 30ms or more. This delay is relatively short compared to video delay.

[0262] There is a significant difference between video processing delay and audio processing delay. The compensation procedure presented in Figure 7 aims to overcome this delay difference and synchronize video and audio. It utilizes information such as the Presentation Time Stamp (PTS) to determine the original timing of the video and audio data, intentionally delaying the output of the audio signal with a shorter delay or making other timing adjustments to ensure that the video and audio are output nearly simultaneously.

[0263] FIG. 8 illustrates an example of a test stream-based calibration procedure for measuring and adjusting the sound pressure level of each speaker based on a user position in a BLE-based audio system proposed in this specification.

[0264] Figure 8 illustrates an example of a test stream-based calibration procedure for measuring and adjusting the sound pressure level (SPL) from each speaker relative to the user's listening position (sweet spot) in a Bluetooth low-latency audio system. This process aims to optimize balanced sound from each speaker in a multi-speaker audio system at the user's primary seating position. This procedure utilizes a measurement device, such as a smartphone, to achieve this goal.

[0265] The calibration process begins with playing a test audio stream to each speaker. As shown in the figure, the user's smartphone or control device individually sends a command to play the test stream to each speaker. Each speaker then plays its own corresponding test sound via a unicast connection. This test stream may be a signal with a specific frequency range or characteristics designed for loudness measurement.

[0266] While the test stream plays through each speaker, the user measures the sound pressure level (SPL) arriving at each speaker using a sound pressure measurement device, such as a smartphone, at their primary listening position (the "Sweet Spot"). The figure shows the user sitting in the center, holding the smartphone, and measuring the SPL values ​​coming from each speaker. The measured SPL values ​​for each speaker position may vary depending on factors such as the distance from the speaker, the speaker's performance, and the surrounding environment (e.g., SPL=60, SPL=80, SPL=30).

[0267] Based on the measured sound pressure level of each speaker, the system adjusts the final audio output. By adjusting the volume or gain of each speaker to compensate for differences in measured SPL values, the system ensures that all speakers sound at the intended relative loudness when the user is listening in the "Sweet Spot." This process compensates for volume differences caused by individual speaker locations or characteristics, and optimizes the overall sound field of the multichannel audio system to the user's location, providing a more immersive sound experience.

[0268] FIG. 9 illustrates an example of an inter-speaker synchronization correction structure for correcting sound synchronization error due to a difference in distance between a TV speaker and a rear speaker in a multi-channel audio system proposed in this specification.

[0269] FIG. 10 illustrates an example of a speaker-to-speaker synchronization structure for compensating for sound synchronization errors due to distance differences between rear speakers in a multi-channel audio system proposed in this specification.

[0270] Figures 9 and 10 illustrate various examples of inter-speaker synchronization structures for compensating for acoustic synchronization errors caused by distance differences between multiple speakers and the user's listening position in a multichannel audio system. Since sound propagates through the air at a finite speed, if each speaker is located at a different distance from the listener, the time it takes for the sound to reach the listening position also varies. This difference in sound arrival times can distort the accurate spatial perception and sound image localization of multichannel sound.

[0271] Figure 9 illustrates the effect of the distance difference between the TV speakers (which typically serve as front speakers) and the rear speakers on audio synchronization. Figure 9 shows that the rear speakers are located further away from the listener than the TV speakers (e.g., 3 meters), causing sound from the rear speakers to arrive at the listening position later than sound from the TV speakers. Even though the system transmits audio signals simultaneously, the listener experiences a temporal mismatch due to the physical distance difference.

[0272] Figure 10 illustrates the effect of distance differences between rear speakers on synchronization. The left and right rear speakers may not be positioned exactly the same distance from the listener, and the figure assumes one rear speaker is slightly further away than the other (e.g., a distance difference of 3 meters). Even these slight distance differences between speakers can cause sound arrival times to vary, and especially in sophisticated surround sound environments, these errors can lead to distortion of the sound image.

[0273] To compensate for this audio synchronization error caused by distance differences, the system measures the distance between each speaker and the listening position or calculates the difference in sound arrival times based on a preset value. The system then performs compensation by intentionally delaying the audio signal output from speakers closer to the listening position by the calculated difference. In other words, by adjusting the timing of sound from all speakers to arrive at the listening position, the system ensures that even in multichannel systems with speakers in different locations, users experience a precise and consistent soundstage as designed.

[0274] FIG. 11 illustrates an example of an overall system configuration for multi-channel audio transmission between a BLE-based TV and multiple audio receiving devices proposed in this specification and a profile structure based on Surround Sound Audio Profile (SSAP).

[0275] Fig. 11 shows an example of the overall system configuration for multi-channel audio transmission between a BLE-based TV and multiple audio receiving devices proposed in this specification and a profile structure based on the Surround Sound Audio Profile (SSAP). The system of Fig. 11 is structured such that a TV, which is a source device, acts as an LE Audio transmitting device (Tx), and multiple speakers act as LE Audio receiving devices (Rx), and transmits multi-channel audio wirelessly via BLE. The figure shows in detail the relationship between each component and profile / service, from the application / host software to the physical layer.

[0276] On the TV transmitter side, the audio signal is processed by the multi-channel audio processor, then converted into a format suitable for BLE transmission through the multi-CH LC3 encoding process. The encoded audio data is transmitted to the LE ISO CH (Isochronous Channel) layer via the I2S interface, where LE Isochronous Channels are configured to broadcast multi-channel audio streams in a synchronized form. Finally, it is wirelessly transmitted to the speakers through the BLE Tx PHY / MAC layer, demonstrating that the data transmission rate can range from 2 Mbps to a maximum of 8 Mbps.

[0277] On the speaker receiving device side, LE ISO CH broadcast data transmitted through BLE Tx / Rx PHY / MAC layers is received. The received data passes through the LE ISO CH layer and is restored to the original multi-channel audio signal through the Multi-CH LC3 audio decoding process. The decoded audio signal is output as sound through the speaker driver. Each speaker receives and plays the audio data of the channel it is responsible for, thereby implementing multi-channel sound. On the speaker side, there are upper layers such as LE Audio Profiles, Sync, and SSAP, which are responsible for interaction and control with the TV.

[0278] In the system of Fig. 11, the Surround Sound Audio Profile (SSAP) and the BLE Audio profiles that form its basis play a crucial role. The Broadcast Audio Profile (BAP) defines the basic functions of audio broadcasting, the Published Audio Capabilities (PAC) provide audio-related capability information including codecs and speaker capabilities, and the Audio Stream Control (ASC) manages audio stream control, QoS, positioning, delay, etc. SSAP can be viewed as a higher-level profile structure that utilizes these sub-profiles to define and control speaker configuration, role assignment, synchronization, etc. required for specific multi-channel audio scenarios such as surround sound.

[0279] Table 2 below illustrates Surround Sound Audio Profile (SSAP) Functions that can be applied to the embodiments proposed in this specification.

[0280]

[0281] Table 3 below illustrates operations related to speaker synchronization that can be applied to embodiments proposed in this specification.

[0282]

[0283] Table 4 below illustrates operations for volume synchronization that can be applied to embodiments proposed in this specification.

[0284]

[0285] FIG. 12 is a diagram illustrating a link related to initial volume setting in a multi-channel audio environment proposed in this specification.

[0286] Referring to FIG. 12, a TV or a sound bar can act as a source. The TV can be connected to the sound bar using a High-Definition Multimedia Interface (HDMI) cable or an optical cable. The source (e.g., a sound bar) can be connected to speakers associated with a surround sound system (e.g., BLE audio speakers, woofers, etc.).

[0287] The channels (CH1, CH2, Ch3, Ch4) associated with the above speakers may include i) a Front Left (FL) channel, ii) a Front Right (FR) channel, iii) a Rear Left (RL) channel, and iv) a Rear Right (RR) channel.

[0288] In a multi-channel audio environment, an initial volume configuration can be transmitted from the source to each speaker based on a Low Energy Asynchronous Connection-Less (LE ACL) link. For example, the source can set the volume of connected speakers (e.g., BLE connected sink speakers) via a Volume Control Profile (VCP). In one embodiment, a volume setting for locking the volume control of each speaker to a defined / determined output (e.g., a common maximum value or a middle value) can be transmitted based on the LE ACL link. This will be described in detail later.

[0289] FIG. 13 is a diagram illustrating channels related to volume control during playback in a multi-channel audio environment proposed in this specification.

[0290] A source (e.g., a sound bar or a TV) can set / control the volume of each channel audio (each CH audio) of a sink speaker based on ISO CH. Referring to FIG. 13, a source (e.g., a sound bar or a TV) can transmit audio data (e.g., LC3 encoded audio data) to each speaker based on LE ISO (Low Energy Isochronous) channels. In one embodiment, before the audio data / packets are encoded / transmitted by the source, the volume of each audio PCM (Pulse Code Modulation) data is adjusted at the source (source device gain control). In one embodiment, audio data (e.g., BIS (Broadcast Isochronous Stream)) can be transmitted together with volume control data for each speaker (speaker device gain control).

[0291] Below, a method for fixing the volume of a speaker and adjusting the size of the sound from a transmitter (Source device Gain Control) in a multi-channel audio environment is described with reference to FIGS. 14 and 15.

[0292] FIG. 14 is a diagram illustrating an initial volume setting related to source gain control according to one embodiment of the present specification.

[0293] Referring to FIGS. 12 and 14, the source transmits volume settings for four speakers based on LE ACL links (ACL 1 to ACL 4). Based on the volume settings, calibration can be performed to lock a common maximum volume. Specifically, based on the volume settings, the volume control of each speaker is locked to a maximum output value (e.g., common maximum SPL output). The volume settings can be based on the characteristics of Table 5 below (e.g., Type of Volume Control, Max SPL Output Volume Setting, Volume Status).

[0294] Table 5 below illustrates sink characteristics for volume control and calibration that can be applied to embodiments proposed in this specification.

[0295]

[0296] FIG. 15 is a diagram illustrating volume control during playback in connection with source gain control according to one embodiment of the present specification.

[0297] Referring to FIGS. 13 and 15, the source transmits audio data (e.g., LC3 encoded audio data) (BIS1 to BIS4) for each of four speakers (FL, FR, RL, RR) within an ISO interval. The audio data may be transmitted based on LE ISO CH.

[0298] Referring to the example in Fig. 15, the volume associated with each speaker can be adjusted as follows.

[0299] Before the audio data (BIS1) for the first speaker (CH1: FL) is encoded, the source adjusts the volume of the audio PCM data to 60.

[0300] Before the audio data (BIS2) for the second speaker (CH2: FR) is encoded, the source adjusts the volume of the audio PCM data to 63.

[0301] Before the audio data (BIS3) for the third speaker (Ch3: RL) is encoded, the source adjusts the volume of the audio PCM data to 55.

[0302] Before the audio data (BIS4) for the fourth speaker (Ch4: RR) is encoded, the source adjusts the volume of the audio PCM data to 52.

[0303] FIG. 16 is a diagram illustrating a state in which the volume of speakers is controlled based on source gain control according to one embodiment of the present specification.

[0304] Below, a method for adjusting the volume value for each speaker (Speaker device Gain Control) when the SPL value for each speaker is known in a multi-channel audio environment is described with reference to FIGS. 17 and 18.

[0305] FIG. 17 is a diagram illustrating an initial volume setting related to speaker gain control according to another embodiment of the present specification.

[0306] Referring to FIGS. 12 and 17, the source transmits volume settings for four speakers based on LE ACL links (ACL 1 to ACL 4). Based on the volume settings, calibration can be performed to lock a common middle volume. Specifically, based on the volume settings, the volume control of each speaker is locked to a middle output value (e.g., common middle output) (Vol=50(Middle)). The volume settings can be based on the characteristics of Table 5 (e.g., Type of Volume Control, Middle Output Volume, Volume Status).

[0307] FIG. 18 is a diagram illustrating volume control during playback in connection with speaker gain control according to another embodiment of the present specification.

[0308] Referring to FIGS. 13 and 18, the source transmits audio data (e.g., LC3 encoded audio data) (BIS1 to BIS4) along with volume control data for each of four speakers (FL, FR, RL, RR) within an ISO interval. The audio data and the volume control data may be transmitted based on LE ISO CH.

[0309] Referring to the example of Fig. 18, the volume control data can be determined as follows. The source can determine the volume control data for each speaker as 0, 0, -5, -8 based on the SPL characteristic (e.g., SPL value) of each speaker (FL, FR, RL RR).

[0310] FIG. 19 is a diagram illustrating a state in which the volume of speakers is controlled based on speaker gain control according to another embodiment of the present specification.

[0311] FIG. 20 is a diagram illustrating volume control of four speakers within a Broadcast Isochronous Group (BIG) based on speaker gain control according to another embodiment of the present specification.

[0312] Referring to Figure 20, ISO / ACL-based operations are performed for each time interval.

[0313] Within an ISO interval, the source transmits audio data (BIS1 to BIS4) for each speaker along with volume control data for each sub-interval. The last section within the ISO interval is where ACL-based operations are performed. For example, the following operations can be performed during 400us within the section: the source (Central, C) transmits a configuration / command to speaker N (Peripheral, P) (C -> P), and the speaker N can transmit a request / response / data (e.g., User input Volume Change Request) to the source (P -> C).

[0314] Below, a method for adjusting the volume of multiple speakers using periodic BLE Broadcasts and Responses is examined with reference to FIG. 21.

[0315] By applying Periodic Advertising with Response (PAwR) or ISO CH, the volume status of multiple speakers can be identified and changes can be requested / responded to based on user input.

[0316] For example, sinks (speaker cells) can transmit volume status (e.g. Packet Error Rate, Channel Status (Good / Poor)) responses within the periodic Broadcast interval of a control device (e.g. Source). For example, when necessary, a control device (Broadcaster) can perform an LE ACL connection request (AUX_ CONNECT_REQ) to a specific device (sink, speaker). At this time, the Broadcast and Response cycle interval can be adjusted depending on the number of devices and settings.

[0317] FIG. 21 is a diagram illustrating an operation of adjusting the volume of speakers using periodic BLE broadcast and response according to another embodiment of the present specification.

[0318] Specifically, Fig. 21 shows an example of a channel status response of speakers when the broadcast interval is narrow and the response interval is wide.

[0319] The source (TV or Sound Bar) transmits the channel-specific volume status (Vol Status=50) for each of the four speakers based on the Broadcast Slots at every periodic advertising subevent interval (e.g. PAwR Subevent#0, PAwR Subevent#1, ..).

[0320] Each speaker (Speaker 1-4) transmits a response to the source based on the sink response slots. The spacing of each slot can be defined as the periodic advertising response slot spacing. The response of Speaker 1 indicates a volume change (+3). The responses of Speakers 2 and 3 indicate a volume status (50). The response of Speaker 4 indicates a volume change (-5).

[0321] The embodiments described below are specifically described with reference to FIG. 22 in terms of the operation of a source (e.g., a TV device). The methods described below are distinguished for convenience of explanation, and it is understood that some components of one method may be substituted for some components of another method, or may be applied in combination with each other, as long as they are not mutually exclusive.

[0322] FIG. 22 is a flowchart illustrating a method performed by a source according to one embodiment of the present specification.

[0323] According to various embodiments of the present specification, a method is provided that is performed by a source such as a TV that supports a short-range communication system such as Bluetooth.

[0324] The source includes a first processor corresponding to a host stack; a second processor corresponding to a first controller stack; a memory; and a transceiver. The host stack and the controller stack are connected via a Host Controller Interface (HCI).

[0325] In the S2210, a source connects to speakers associated with the surround sound system. For example, the source can scan the advertisements of speakers and then connect to each speaker. Each speaker's advertisement indicates its availability and support for the Surround Sound Audio Profile (SSAP).

[0326] In S2220, the source transmits information related to a volume control procedure to each speaker. For example, the information may be based on an initial volume setting or volume control data. For example, the information may be related to source gain adjustment or speaker gain adjustment.

[0327] In one embodiment, the volume control procedure is based on the information related to the source gain adjustment: the volume control of each speaker is locked to a common maximum Sound Pressure Level (SPL, ouput) based on the information, and the volume of all audio data (e.g., all audio channels / streams) in the Pulse Code Modulation (PCM) domain of the source is adjusted prior to audio encoding and transmission. This embodiment may be based on FIGS. 14 and 15.

[0328] In one embodiment, the information related to the source gain adjustment may include a volume setting based on a Volume Control Profile (VCP).

[0329] In one embodiment, the information related to the source gain adjustment may be transmitted based on a Low Energy Asynchronous Connection-Less (LE ACL) link.

[0330] In one embodiment, an audio signal for each of the speakers may be transmitted based on a Low Energy Isochronous (LE ISO) channel.

[0331] In one embodiment, the audio signal may be based on a Broadcast Isochronous Stream (BIS).

[0332] In one embodiment, the BIS for each of the speakers may be transmitted within an ISO sub interval.

[0333] In one embodiment, the volume control procedure is based on speaker gain adjustment: the information may be transmitted together with an audio signal based on broadcast streaming, and the local gain of each speaker may be adjusted based on the information. This embodiment may be based on FIG. 18. For example, the audio signal may be based on BIS1 to BIS4 of FIG. 18, and the information may be based on volume control data of FIG. 18.

[0334] In one embodiment, the information related to the speaker gain adjustment may include a volume setting of each of the speakers. The volume setting may be determined based on an SPL characteristic of each of the speakers.

[0335] In one embodiment, the channels associated with the speakers may include at least one of i) a Front Left (FL) channel, ii) a Front Right (FR) channel, iii) a Rear Left (RL) channel, and / or iv) a Rear Right (RR) channel.

[0336] In one embodiment, the method may further include the step of transmitting the volume status of each channel of the source to each speaker within a periodic broadcast interval, and the step of receiving a response from each of the speakers within a periodic response interval. For example, the response may include information related to i) the volume status of each speaker and / or ii) volume adjustment of each speaker. This embodiment may be based on FIG. 21.

[0337] According to various embodiments of the present disclosure, a control device for controlling a source is provided. The control device includes at least one processor and at least one memory operably connected to the at least one processor. The at least one memory may be configured to store instructions for performing the operating method of the source according to FIG. 22 based on execution by the at least one processor.

[0338] According to various embodiments of the present disclosure, one or more non-transitory computer-readable media (CRM) storing one or more instructions are provided. The one or more instructions, when executed by one or more processors, perform operations, and the operations may include the method of operating a source according to FIG. 22.

[0339] The embodiments described below are specifically described with reference to FIG. 23 in terms of speaker operation. The methods described below are distinguished for convenience of explanation, and it is understood that some components of one method may be substituted for or combined with some components of another method, as long as they are not mutually exclusive.

[0340] FIG. 23 is a flowchart illustrating a method performed by a speaker according to another embodiment of the present specification.

[0341] According to various embodiments of the present specification, a method is provided that is performed by a speaker supporting a short-range communication system such as Bluetooth.

[0342] The speaker includes a third processor corresponding to a host stack; a fourth processor corresponding to a third controller stack; memory; and a transceiver. The host stack and the controller stack are connected via a Host Controller Interface (HCI).

[0343] In the S2310, the speaker connects to a source associated with the surround sound system. For example, the speaker transmits an advertisement indicating availability and support for the Surround Sound Audio Profile (SSAP). The speaker can connect to the source that scanned the advertisement.

[0344] In S2320, the speaker receives information related to the volume control procedure from the source.

[0345] In one embodiment, the volume control procedure is based on a source gain adjustment: based on the information, the volume control of the speaker is locked to a common maximum Sound Pressure Level (SPL) output, and the volume of all audio data in the Pulse Code Modulation (PCM) domain of the source is adjusted prior to audio encoding and transmission by the source. This embodiment may be based on FIGS. 14 and 15.

[0346] In one embodiment, the information related to the source gain adjustment may include a volume setting based on a Volume Control Profile (VCP).

[0347] In one embodiment, the information related to the source gain adjustment may be received based on a Low Energy Asynchronous Connection-Less (LE ACL) link.

[0348] In one embodiment, an audio signal for the speaker may be transmitted from a source based on a Low Energy Isochronous (LE ISO) channel.

[0349] In one embodiment, the audio signal may be based on a Broadcast Isochronous Stream (BIS).

[0350] In one embodiment, the BIS for the speaker may be transmitted within an ISO sub interval.

[0351] In one embodiment, the volume control procedure is based on speaker gain adjustment: the information may be received together with an audio signal based on broadcast streaming, and the local gain of the speaker may be adjusted based on the information. This embodiment may be based on FIG. 18. For example, the audio signal may be based on one of BIS1 to BIS4 of FIG. 18, and the information may be based on volume control data of FIG. 18.

[0352] In one embodiment, the information related to the speaker gain adjustment may include a volume setting of the speaker. The volume setting may be determined by the source based on an SPL characteristic of the speaker.

[0353] In one embodiment, the channel associated with the speaker may be i) a Front Left (FL) channel, ii) a Front Right (FR) channel, iii) a Rear Left (RL) channel, or iv) a Rear Right (RR) channel.

[0354] In one embodiment, the method may further include the step of receiving a channel-specific volume status from the source within a periodic broadcast interval and the step of transmitting a response to the source within a periodic response interval. As an example, the response may include information related to i) a volume status of the speaker and / or ii) volume adjustment of the speaker. This embodiment may be based on FIG. 21.

[0355] According to various embodiments of the present disclosure, a speaker is provided. The speaker includes a third processor corresponding to a host stack; a fourth processor corresponding to a third controller stack; a memory; a transceiver; and a speaker device. The host stack and the controller stack are connected via a Host Controller Interface (HCI). The memory may be configured to store instructions for performing a method of operating a speaker according to FIG. 23 based on instructions executed by the third processor and the fourth processor.

[0356] According to various embodiments of the present disclosure, a control device for controlling a speaker is provided. The control device includes at least one processor and at least one memory operably connected to the at least one processor. The at least one memory may be configured to store instructions for performing a method for operating a speaker according to FIG. 23 based on instructions executed by the at least one processor.

[0357] According to various embodiments of the present disclosure, one or more non-transitory computer-readable media (CRM) storing one or more instructions are provided. The one or more instructions, when executed by one or more processors, perform operations, and the operations may include a method of operating a speaker according to FIG. 23.

[0358] The claims described in the various embodiments of this specification may be combined in various ways. For example, the technical features of the method claims of the various embodiments of this specification may be combined and implemented as a device, and the technical features of the device claims of the various embodiments of this specification may be combined and implemented as a method. Furthermore, the technical features of the method claims of the various embodiments of this specification may be combined with the technical features of the device claims of the various embodiments of this specification may be combined and implemented as a device, and the technical features of the method claims of the various embodiments of this specification may be combined with the technical features of the device claims of the various embodiments of this specification may be combined and implemented as a method.

Claims

1. In a method performed by a source, Steps for connecting speakers related to a surround sound system; and A step of transmitting information related to a volume control procedure to each speaker; Based on the above volume control procedure being related to source gain adjustment: Based on the above information, the volume control of each speaker is locked to the common maximum Sound Pressure Level (SPL, ouput). A method characterized in that the volume of all audio data in the Pulse Code Modulation (PCM) domain of the source is adjusted prior to audio encoding and transmission.

2. In paragraph 1, A method characterized in that the information related to the source gain adjustment includes a volume setting based on a volume control profile (VCP).

3. In paragraph 1, A method characterized in that the information related to the source gain adjustment is transmitted based on a Low Energy Asynchronous Connection-Less (LE ACL) link.

4. In paragraph 1, A method characterized in that an audio signal for each of the above speakers is transmitted based on an LE ISO (Low Energy Isochronous) channel.

5. In paragraph 4, A method characterized in that the above audio signal is based on a BIS (Broadcast Isochronous Stream).

6. In paragraph 5, A method characterized in that the BIS for each of the above speakers is transmitted within an ISO sub interval.

7. In paragraph 1, Based on the above volume control procedure being related to speaker gain adjustment: The above information is transmitted together with an audio signal based on broadcast streaming, A method characterized in that the local gain of each speaker is adjusted based on the above information.

8. In paragraph 7, The information related to the speaker gain adjustment includes the volume setting of each of the speakers, A method characterized in that the above volume setting is determined based on the SPL characteristic of each of the speakers.

9. In paragraph 1, A method characterized in that the channels associated with the above speakers include at least one of i) a Front Left (FL) channel, ii) a Front Right (FR) channel, iii) a Rear Left (RL) channel, and / or iv) a Rear Right (RR) channel.

10. In paragraph 1, A step of transmitting the volume status of each channel of the source to each speaker within a periodic broadcast interval; and Further comprising the step of receiving a response from each of the speakers within a periodic response interval, A method characterized in that the above response includes information related to i) the volume status of each speaker and / or ii) volume adjustment of each speaker.

11. In terms of source, A first processor corresponding to a host stack; a second processor corresponding to a first controller stack; a memory; and a transceiver, The above host stack and the above controller stack are connected through HCI (Host Controller Interface), A source characterized in that the memory stores instructions that cause the source to perform all steps according to the method of any one of claims 1 to 10 based on being executed by the first processor and the second processor.

12. In a method performed by a speaker (source), A step of connecting a source related to a surround sound system; and A step of receiving information related to a volume control procedure from the above source; Based on the above volume control procedure being related to source gain adjustment: Based on the above information, the volume control of the speaker is locked to the common maximum Sound Pressure Level (SPL, ouput), A method characterized in that the volume of all audio data in the pulse code modulation (PCM) domain of the source is adjusted prior to audio encoding and transmission by the source.

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