Audio endpoint

Streams encoded audio frames from the watch to the phone. More...

Data Structures
struct	DataTransferMsg
	Audio data message. More...
struct	StopTransferMsg
	Stop transfer message. More...

Macros
#define	AUDIO_ENDPOINT_SESSION_INVALID_ID   (0)
	Invalid session identifier.

Typedefs
typedef uint16_t	AudioEndpointSessionId
	Identifies a transfer session.
typedef void(*	AudioEndpointStopTransferCallback) (AudioEndpointSessionId session_id)
	Called when the phone asks to stop a transfer.

Enumerations
enum	MsgId { MsgIdDataTransfer = 0x02 , MsgIdStopTransfer = 0x03 }
	Audio endpoint message types. More...

Functions
AudioEndpointSessionId	audio_endpoint_setup_transfer (AudioEndpointStopTransferCallback stop_transfer)
	Create a session for transferring audio from the watch to the phone.
void	audio_endpoint_add_frame (AudioEndpointSessionId session_id, uint8_t *frame, uint8_t frame_size)
	Send a frame of encoded audio.
void	audio_endpoint_stop_transfer (AudioEndpointSessionId session_id)
	End a transfer and send a stop transfer message to the phone.
void	audio_endpoint_cancel_transfer (AudioEndpointSessionId session_id)
	End a transfer without notifying the phone.

Detailed Description

Streams encoded audio frames from the watch to the phone.

Only one transfer session can be active at a time. While a session is active, the Bluetooth connection is kept in its low latency mode. Frames that do not fit in the send buffer are dropped.

AudioEndpointSessionId id = audio_endpoint_setup_transfer(stop_cb);
if (id != AUDIO_ENDPOINT_SESSION_INVALID_ID) {
  audio_endpoint_add_frame(id, frame, frame_size);
  audio_endpoint_stop_transfer(id);
}

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Data Structure Documentation

DataTransferMsg

struct DataTransferMsg

Audio data message.

Data Fields
uint8_t	frame_count	Number of frames that follow.
uint8_t	frames[]	Frames, each a length byte followed by that many bytes of encoded audio.
MsgId	msg_id	MsgIdDataTransfer.
AudioEndpointSessionId	session_id	Transfer session.

StopTransferMsg

struct StopTransferMsg

Stop transfer message.

Data Fields
MsgId	msg_id	MsgIdStopTransfer.
AudioEndpointSessionId	session_id	Transfer session.

Macro Definition Documentation

AUDIO_ENDPOINT_SESSION_INVALID_ID

#define AUDIO_ENDPOINT_SESSION_INVALID_ID   (0)

Invalid session identifier.

Typedef Documentation

AudioEndpointSessionId

typedef uint16_t AudioEndpointSessionId

Identifies a transfer session.

AudioEndpointStopTransferCallback

typedef void(* AudioEndpointStopTransferCallback) (AudioEndpointSessionId session_id)

Called when the phone asks to stop a transfer.

Parameters

session_id

Session being stopped.

Enumeration Type Documentation

MsgId

enum MsgId

Audio endpoint message types.

Enumerator
MsgIdDataTransfer	Audio frames, watch to phone.
MsgIdStopTransfer	End of transfer, in either direction.

Function Documentation

audio_endpoint_add_frame()

void audio_endpoint_add_frame	(	AudioEndpointSessionId	session_id,
		uint8_t *	frame,
		uint8_t	frame_size
	)

Send a frame of encoded audio.

Ignored if session_id is not the active session. Never blocks; the frame is dropped if the send buffer is full.

Parameters

session_id	Session returned by audio_endpoint_setup_transfer().
frame	Encoded audio data.
frame_size	Size of frame in bytes.

audio_endpoint_cancel_transfer()

void audio_endpoint_cancel_transfer

(

AudioEndpointSessionId

session_id

)

End a transfer without notifying the phone.

The stop callback is not called.

Parameters

session_id

Session returned by audio_endpoint_setup_transfer().

audio_endpoint_setup_transfer()

AudioEndpointSessionId audio_endpoint_setup_transfer

(

AudioEndpointStopTransferCallback

stop_transfer

)

Create a session for transferring audio from the watch to the phone.

Parameters

stop_transfer

Called when the phone sends a stop transfer message.

Returns

Session identifier, or AUDIO_ENDPOINT_SESSION_INVALID_ID if a session is already active.

audio_endpoint_stop_transfer()

void audio_endpoint_stop_transfer

(

AudioEndpointSessionId

session_id

)

End a transfer and send a stop transfer message to the phone.

The stop callback is not called.

Parameters

session_id

Session returned by audio_endpoint_setup_transfer().