[ English | 简体中文 ]

Bluetooth A2DP API

The openvela Bluetooth A2DP (Advanced Audio Distribution Profile) interface supports audio stream sending (Source) and receiving (Sink).

Header files: #include "bt_a2dp.h", #include "bt_a2dp_sink.h", #include "bt_a2dp_source.h"

openvela Implementation Notes

• Dual-role support: Source (audio sender) and Sink (audio receiver)
• Codecs: Supports SBC and AAC
• Transport modes: Supports hardware offloading and non-offloading modes

Connection State Machine

The state transitions during A2DP connection establishment, audio streaming, and disconnection are shown below:

State definitions:

• Idle: No A2DP connection is established.
• Opening: An A2DP connection is being established (after the local side initiates A2DP connect).
• Opened: The A2DP signaling connection has been established and the audio stream is ready.
• Started: The audio stream has started and audio data is being transmitted.
• Closing: The A2DP connection is being torn down until the peer confirms A2DP disconnected.

Synchronous Interfaces

bt_a2dp_sink_unregister_callbacks

bool bt_a2dp_sink_unregister_callbacks(bt_instance_t* ins, void* cookie);

Unregister callback functions and stop receiving state change notifications.

Parameters:

• ins Bluetooth client instance.
• cookie User context.

Returns:

Returns true on success, false on failure.

bt_a2dp_sink_is_connected

bool bt_a2dp_sink_is_connected(bt_instance_t* ins, bt_address_t* addr);

Check whether the A2DP Sink is connected to the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the peer device.

Returns:

Returns true if connected, false otherwise.

bt_a2dp_sink_is_playing

bool bt_a2dp_sink_is_playing(bt_instance_t* ins, bt_address_t* addr);

Check whether audio is currently playing.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the peer device.

Returns:

Returns true if playing, false otherwise.

bt_a2dp_sink_get_connection_state

profile_connection_state_t bt_a2dp_sink_get_connection_state(bt_instance_t* ins, bt_address_t* addr);

Get the A2DP Sink connection state with the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the remote device.

Returns:

Returns the current connection state.

bt_a2dp_sink_connect

bt_status_t bt_a2dp_sink_connect(bt_instance_t* ins, bt_address_t* addr);

Initiate an A2DP Sink connection to the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the peer device.

Returns:

Returns BT_STATUS_SUCCESS on success, or an error code on failure.

bt_a2dp_sink_disconnect

bt_status_t bt_a2dp_sink_disconnect(bt_instance_t* ins, bt_address_t* addr);

Disconnect the A2DP Sink connection from the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the peer device.

Returns:

Returns BT_STATUS_SUCCESS on success, or an error code on failure.

bt_a2dp_source_unregister_callbacks

bool bt_a2dp_source_unregister_callbacks(bt_instance_t* ins, void* cookie);

Unregister callback functions and stop receiving state change notifications.

Parameters:

• ins Bluetooth client instance.
• cookie User context.

Returns:

Returns true on success, false on failure.

bt_a2dp_source_is_connected

bool bt_a2dp_source_is_connected(bt_instance_t* ins, bt_address_t* addr);

Check whether the A2DP Source is connected to the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the peer device.

Returns:

Returns true if connected, false otherwise.

bt_a2dp_source_is_playing

bool bt_a2dp_source_is_playing(bt_instance_t* ins, bt_address_t* addr);

Check whether audio is currently playing.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the peer device.

Returns:

Returns true if playing, false otherwise.

bt_a2dp_source_get_connection_state

profile_connection_state_t bt_a2dp_source_get_connection_state(bt_instance_t* ins, bt_address_t* addr);

Get the A2DP Source connection state with the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the remote device.

Returns:

Returns the current connection state.

bt_a2dp_source_connect

bt_status_t bt_a2dp_source_connect(bt_instance_t* ins, bt_address_t* addr);

Initiate an A2DP Source connection to the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the peer device.

Returns:

Returns BT_STATUS_SUCCESS on success, or an error code on failure.

bt_a2dp_source_disconnect

bt_status_t bt_a2dp_source_disconnect(bt_instance_t* ins, bt_address_t* addr);

Disconnect the A2DP Source connection from the remote device.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the remote device.

Returns:

Returns BT_STATUS_SUCCESS on success, or an error code on failure.

bt_a2dp_source_set_silence_device

bt_status_t bt_a2dp_source_set_silence_device(bt_instance_t* ins, bt_address_t* addr, bool silence);

Set the device to silence mode.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the remote device.
• silence Whether to enable silence mode (true for silent).

Returns:

Returns BT_STATUS_SUCCESS on success, or an error code on failure.

bt_a2dp_source_set_active_device

bt_status_t bt_a2dp_source_set_active_device(bt_instance_t* ins, bt_address_t* addr);

Set the active device for A2DP Source.

Parameters:

• ins Bluetooth client instance.
• addr Bluetooth address of the remote device.

Returns:

Returns BT_STATUS_SUCCESS on success, or an error code on failure.