# Bluetooth® A2DP API

## Application Examples

- bluetooth/bluedroid/classic_bt/a2dp_sink demonstrates how to implement an audio sink device using the Advanced Audio Distribution Profile (A2DP) to receive audio streams. This example also shows how to use AVRCP for media information notifications and I2S for audio stream output.

- bluetooth/bluedroid/classic_bt/a2dp_source demonstrates how to use A2DP APIs to transmit audio streams.

- bluetooth/bluedroid/coex/a2dp_gatts_coex demonstrates how to use the ESP-IDF A2DP-GATTS_COEX demo to create a GATT service and A2DP profile.

## API Reference

### Header File

- components/bt/host/bluedroid/api/include/api/esp_a2dp_api.h

- This header file can be included with:

  >     #include "esp_a2dp_api.h"

- This header file is a part of the API provided by the `bt` component. To declare that your component depends on `bt`, add the following to your CMakeLists.txt:

  >     REQUIRES bt

  > or

  >     PRIV_REQUIRES bt

### Functions

esp_a2d_audio_buff_t *esp_a2d_audio_buff_alloc(uint16_t size)

  Allocate a audio buffer to store and send audio data, can be used in both sink and source.

  Parameters:

    size -- [in] buffer size to allocate

  Returns:

    allocated audio buffer, if Bluedroid is not enabled, no memory, or size is zeros, will return NULL

void esp_a2d_audio_buff_free(esp_a2d_audio_buff_t *audio_buf)

  Free a audio buffer allocated by esp_a2d_audio_buff_alloc.

  Parameters:

    audio_buf -- [in] audio buffer to free

esp_err_t esp_a2d_register_callback(esp_a2d_cb_t callback)

  Register application callback function to A2DP module. This function should be called only after esp_bluedroid_enable() completes successfully, used by both A2DP source and sink.

  Parameters:

    callback -- [in] A2DP event callback function

  Returns:

    - ESP_OK: success

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: if callback is a NULL function pointer

esp_err_t esp_a2d_sink_register_audio_data_callback(esp_a2d_sink_audio_data_cb_t callback)

  Register A2DP sink audio data output function, the output format is undecoded audio data frame in esp_a2d_audio_buff_t, user shall call esp_a2d_audio_buff_free to free the buff when the data is consumed.

  Parameters:

    callback -- [in] A2DP sink audio data callback function

  Returns:

    - ESP_OK: success

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_sink_init(void)

  Initialize the bluetooth A2DP sink module. This function should be called after esp_bluedroid_enable() completes successfully, and ESP_A2D_PROF_STATE_EVT with ESP_A2D_INIT_SUCCESS will reported to the APP layer. Note: A2DP can work independently. If you want to use AVRC together, you should initiate AVRC first. This function should be called after esp_bluedroid_enable() completes successfully.

  Returns:

    - ESP_OK: if the initialization request is sent successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_sink_register_stream_endpoint(uint8_t seid, const esp_a2d_mcc_t *mcc)

  Register a a2dp sink Stream Endpoint (SEP) with specific codec capability, shall register SEP after a2dp sink initializing and before a2dp connection establishing. Register the same SEP index repeatedly will overwrite the old one.

  Parameters:

    - seid -- [in] local SEP identifier, start from 0, less than ESP_A2D_MAX_SEPS

    - mcc -- [in] codec capability, currently only supports SBC

  Returns:

    - ESP_OK: success

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_ERR_INVALID_ARG: invalid parameter

    - ESP_FAIL: others

esp_err_t esp_a2d_sink_deinit(void)

  De-initialize for A2DP sink module. This function should be called only after esp_bluedroid_enable() completes successfully, and ESP_A2D_PROF_STATE_EVT with ESP_A2D_DEINIT_SUCCESS will reported to APP layer.

  Returns:

    - ESP_OK: if the deinitialization request is sent successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_sink_connect(esp_bd_addr_t remote_bda)

  Connect to remote bluetooth A2DP source device. This API must be called after esp_a2d_sink_init() and before esp_a2d_sink_deinit().

  Parameters:

    remote_bda -- [in] remote bluetooth device address

  Returns:

    - ESP_OK: connect request is sent to lower layer successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_sink_disconnect(esp_bd_addr_t remote_bda)

  Disconnect from the remote A2DP source device. This API must be called after esp_a2d_sink_init() and before esp_a2d_sink_deinit().

  Parameters:

    remote_bda -- [in] remote bluetooth device address

  Returns:

    - ESP_OK: disconnect request is sent to lower layer successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_sink_set_delay_value(uint16_t delay_value)

  Set delay reporting value. The delay value of sink is caused by buffering (including protocol stack and application layer), decoding and rendering. The default delay value is 120ms, if the set value is less than 120ms, the setting will fail. This API must be called after esp_a2d_sink_init() and before esp_a2d_sink_deinit().

  Parameters:

    delay_value -- [in] reporting value is in 1/10 millisecond

  Returns:

    - ESP_OK: delay value is sent to lower layer successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_sink_get_delay_value(void)

  Get delay reporting value. This API must be called after esp_a2d_sink_init() and before esp_a2d_sink_deinit().

  Returns:

    - ESP_OK: if the request is sent successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_media_ctrl(esp_a2d_media_ctrl_t ctrl)

  Media control commands. This API can be used for both A2DP sink and source and must be called after esp_a2d_sink_init() and before esp_a2d_sink_deinit().

  Parameters:

    ctrl -- [in] control commands for A2DP data channel

  Returns:

    - ESP_OK: control command is sent to lower layer successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_get_profile_status(esp_a2d_profile_status_t *profile_status)

  This function is used to get the status of A2DP.

  Parameters:

    profile_status -- [out] - A2DP status

  Returns:

    - ESP_OK: success

    - other: failed

esp_err_t esp_a2d_source_init(void)

  Initialize the bluetooth A2DP source module. A2DP can work independently. If you want to use AVRC together, you should initiate AVRC first. This function should be called after esp_bluedroid_enable() completes successfully, and ESP_A2D_PROF_STATE_EVT with ESP_A2D_INIT_SUCCESS will reported to the APP layer. Note: A2DP can work independently. If you want to use AVRC together, you should initiate AVRC first.

  Returns:

    - ESP_OK: if the initialization request is sent to lower layer successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_source_register_stream_endpoint(uint8_t seid, const esp_a2d_mcc_t *mcc)

  Register a a2dp source Stream Endpoint (SEP) with specific codec capability, shall register SEP after a2dp source initializing and before a2dp connection establishing. Register the same SEP index repeatedly will overwrite the old one.

  Parameters:

    - seid -- [in] local SEP identifier, start from 0, less than ESP_A2D_MAX_SEPS

    - mcc -- [in] codec capability, currently, only SBC supported

  Returns:

    - ESP_OK: success

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_ERR_INVALID_ARG: invalid parameter

    - ESP_FAIL: others

esp_err_t esp_a2d_source_deinit(void)

  De-initialize for A2DP source module. This function should be called only after esp_bluedroid_enable() completes successfully, and ESP_A2D_PROF_STATE_EVT with ESP_A2D_DEINIT_SUCCESS will reported to APP layer.

  Returns:

    - ESP_OK: success

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_source_audio_data_send(esp_a2d_conn_hdl_t conn_hdl, esp_a2d_audio_buff_t *audio_buf)

  Send a audio buff with encoded audio data to sink, the audio data len shall not bigger than audio connection mtu (retrieved from ESP_A2D_CONNECTION_STATE_EVT). if the return value is ESP_OK, then the audio buff is consumed, otherwise, audio buff can be reused by user.

  Parameters:

    - conn_hdl -- [in] connection handle

    - audio_buf -- [in] encoded audio data

  Returns:

    - ESP_OK: success

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_ERR_INVALID_ARG: invalid parameter

    - ESP_ERR_INVALID_SIZE: data len bigger than mtu

    - ESP_FAIL: buffer queue is full, try again later

esp_err_t esp_a2d_source_connect(esp_bd_addr_t remote_bda)

  Connect to remote A2DP sink device. This API must be called after esp_a2d_source_init() and before esp_a2d_source_deinit().

  Parameters:

    remote_bda -- [in] remote bluetooth device address

  Returns:

    - ESP_OK: connect request is sent to lower layer successfully

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

esp_err_t esp_a2d_source_disconnect(esp_bd_addr_t remote_bda)

  Disconnect from the remote A2DP sink device. This API must be called after esp_a2d_source_init() and before esp_a2d_source_deinit().

  Parameters:

    remote_bda -- [in] remote bluetooth device address

  Returns:

    - ESP_OK: disconnect request is sent to lower layer

    - ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled

    - ESP_FAIL: others

### Unions

union esp_a2d_cb_param_t
  #include <esp_a2dp_api.h>

  A2DP state callback parameters.

  Public Members

  struct esp_a2d_cb_param_t::a2d_conn_stat_param conn_stat

    A2DP connection status

  struct esp_a2d_cb_param_t::a2d_audio_stat_param audio_stat

    audio stream playing state

  struct esp_a2d_cb_param_t::a2d_audio_cfg_param audio_cfg

    media codec configuration information

  struct esp_a2d_cb_param_t::media_ctrl_stat_param media_ctrl_stat

    status in acknowledgement to media control commands

  struct esp_a2d_cb_param_t::a2d_prof_stat_param a2d_prof_stat

    status to indicate a2d prof init or deinit

  struct esp_a2d_cb_param_t::a2d_sep_reg_stat_param a2d_sep_reg_stat

    status to indicate a2d sep register success or not

  struct esp_a2d_cb_param_t::a2d_psc_cfg_param a2d_psc_cfg_stat

    status to indicate protocol service capabilities configured

  struct esp_a2d_cb_param_t::a2d_set_stat_param a2d_set_delay_value_stat

    A2DP sink set delay report value status

  struct esp_a2d_cb_param_t::a2d_get_stat_param a2d_get_delay_value_stat

    A2DP sink get delay report value status

  struct esp_a2d_cb_param_t::a2d_report_delay_stat_param a2d_report_delay_value_stat

    A2DP source received sink report value status

  struct a2d_audio_cfg_param
    #include <esp_a2dp_api.h>

    ESP_A2D_AUDIO_CFG_EVT.

    Public Members

    esp_bd_addr_t remote_bda

      remote bluetooth device address

    esp_a2d_conn_hdl_t conn_hdl

      connection handle

    esp_a2d_mcc_t mcc

      A2DP media codec capability information

  struct a2d_audio_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_AUDIO_STATE_EVT.

    Public Members

    esp_a2d_audio_state_t state

      one of the values from esp_a2d_audio_state_t

    esp_bd_addr_t remote_bda

      remote bluetooth device address

    esp_a2d_conn_hdl_t conn_hdl

      connection handle

  struct a2d_conn_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_CONNECTION_STATE_EVT.

    Public Members

    esp_a2d_connection_state_t state

      one of values from esp_a2d_connection_state_t

    esp_bd_addr_t remote_bda

      remote bluetooth device address

    esp_a2d_conn_hdl_t conn_hdl

      connection handle

    uint16_t audio_mtu

      MTU of audio connection

    esp_a2d_disc_rsn_t disc_rsn

      reason of disconnection for "DISCONNECTED"

  struct a2d_get_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_SNK_GET_DELAY_VALUE_EVT.

    Public Members

    uint16_t delay_value

      delay report value

  struct a2d_prof_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_PROF_STATE_EVT.

    Public Members

    esp_a2d_init_state_t init_state

      a2dp profile state param

  struct a2d_psc_cfg_param
    #include <esp_a2dp_api.h>

    ESP_A2D_SNK_PSC_CFG_EVT.

    Public Members

    esp_a2d_psc_t psc_mask

      protocol service capabilities configured

  struct a2d_report_delay_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_REPORT_SNK_DELAY_VALUE_EVT.

    Public Members

    uint16_t delay_value

      delay report value

  struct a2d_sep_reg_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_SEP_REG_STATE_EVT.

    Public Members

    uint8_t seid

      the stream endpoint to register

    esp_a2d_sep_reg_state_t reg_state

      stream endpoint register state

  struct a2d_set_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_SNK_SET_DELAY_VALUE_EVT.

    Public Members

    esp_a2d_set_delay_value_state_t set_state

      a2dp profile state param

    uint16_t delay_value

      delay report value

  struct media_ctrl_stat_param
    #include <esp_a2dp_api.h>

    ESP_A2D_MEDIA_CTRL_ACK_EVT.

    Public Members

    esp_a2d_media_ctrl_t cmd

      media control commands to acknowledge

    esp_a2d_media_ctrl_ack_t status

      acknowledgement to media control commands

### Structures

struct esp_a2d_cie_sbc_t

  A2DP SBC media codec capabilities information struct.

  Public Members

  uint8_t ch_mode

    Channel mode

  uint8_t samp_freq

    Sampling frequency

  uint8_t alloc_mthd

    Allocation method

  uint8_t num_subbands

    Number of subbands

  uint8_t block_len

    Block length

  uint8_t min_bitpool

    Minimum bitpool

  uint8_t max_bitpool

    Maximum bitpool

struct esp_a2d_cie_m12_t

  A2DP MPEG-1, 2 media codec capabilities information struct (Not supported yet)

  Public Members

  uint8_t ch_mode

    Channel mode

  uint8_t crc

    CRC protection

  uint8_t layer

    Layers of MPEG-1,2 Audio

  uint8_t samp_freq

    Sampling frequency

  uint8_t mpf

    Media payload format

  uint8_t rfu

    Reserved

  uint8_t bri1

    Bit rate index part 1

  uint8_t vbr

    Support of VBR

  uint8_t bri2

    Bit rate index part 2

struct esp_a2d_cie_m24_t

  A2DP MPEG-2, 4 media codec capabilities information struct (Not supported yet)

  Public Members

  uint8_t drc

    Support of MPEG-D DRC

  uint8_t obj_type

    Object type

  uint8_t samp_freq1

    Sampling frequency part 1

  uint8_t ch

    Channels

  uint8_t samp_freq2

    Sampling frequency part 2

  uint8_t br1

    Bit rate part 1

  uint8_t vbr

    Support of VBR

  uint8_t br2

    Bit rate part 2

  uint8_t br3

    Bit rate part 3

struct esp_a2d_cie_atrac_t

  A2DP ATRAC media codec capabilities information struct (Not supported yet)

  Public Members

  uint8_t rfu1

    Reserved

  uint8_t ch_mode

    Channel mode

  uint8_t version

    Version

  uint8_t bri1

    Bit rate index part 1

  uint8_t vbr

    Support of VBR

  uint8_t samp_freq

    Sampling frequency

  uint8_t rfu2

    Reserved

  uint8_t bri2

    Bit rate index part 2

  uint8_t bri3

    Bit rate index part 3

  uint16_t max_sul

    Maximum SUL

  uint8_t rfu3

    Reserved

struct esp_a2d_mcc_t

  A2DP media codec capabilities union.

  Public Members

  esp_a2d_mct_t type

    A2DP media codec type

  esp_a2d_cie_sbc_t sbc_info

    SBC codec capabilities

  esp_a2d_cie_m12_t m12_info

    MPEG-1,2 audio codec capabilities

  esp_a2d_cie_m24_t m24_info

    MPEG-2, 4 AAC audio codec capabilities

  esp_a2d_cie_atrac_t atrac_info

    ATRAC family codec capabilities

  union esp_a2d_mcc_t cie

    A2DP codec information element

struct esp_a2d_profile_status_t

  A2DP profile status parameters.

  Public Members

  bool a2d_snk_inited

    A2DP sink initialization

  bool a2d_src_inited

    A2DP source initialization

  uint8_t conn_num

    Number of connections

struct esp_a2d_audio_buff_t

  A2DP audio buffer.

  Public Members

  uint16_t buff_size

    audio buff size

  uint16_t number_frame

    number of encoded frame in this buff

  uint32_t timestamp

    timestamp of the first frame

  uint16_t data_len

    audio data len

  uint8_t *data

    pointer to audio data start

### Macros

ESP_A2D_MAX_SEPS

  Maximum number of Stream Endpoint that supported

ESP_A2D_MCT_SBC

  Media codec types supported by A2DP.

  SBC

ESP_A2D_MCT_M12

  MPEG-1, 2 Audio

ESP_A2D_MCT_M24

  MPEG-2, 4 AAC

ESP_A2D_MCT_ATRAC

  ATRAC family

ESP_A2D_MCT_NON_A2DP

  NON-A2DP

ESP_A2D_PSC_DELAY_RPT

  Protocol service capabilities. This value is a mask.

  Delay Report

ESP_A2D_SBC_CIE_SF_16K

  A2DP SBC sampling frequency bit mask in CIE.

  SBC sampling frequency 16kHz

ESP_A2D_SBC_CIE_SF_32K

  SBC sampling frequency 32kHz

ESP_A2D_SBC_CIE_SF_44K

  SBC sampling frequency 44.1kHz

ESP_A2D_SBC_CIE_SF_48K

  SBC sampling frequency 48kHz

ESP_A2D_SBC_CIE_CH_MODE_MONO

  A2DP SBC channel mode bit mask in CIE.

  SBC channel mode Mono

ESP_A2D_SBC_CIE_CH_MODE_DUAL_CHANNEL

  SBC channel mode Dual Channel

ESP_A2D_SBC_CIE_CH_MODE_STEREO

  SBC channel mode Stereo

ESP_A2D_SBC_CIE_CH_MODE_JOINT_STEREO

  SBC channel mode Stereo

ESP_A2D_SBC_CIE_BLOCK_LEN_4

  A2DP SBC block length bit mask in CIE.

  SBC block length 4

ESP_A2D_SBC_CIE_BLOCK_LEN_8

  SBC block length 8

ESP_A2D_SBC_CIE_BLOCK_LEN_12

  SBC block length 12

ESP_A2D_SBC_CIE_BLOCK_LEN_16

  SBC block length 16

ESP_A2D_SBC_CIE_NUM_SUBBANDS_4

  A2DP SBC number of subbands bit mask in CIE.

  SBC number of subbands 4

ESP_A2D_SBC_CIE_NUM_SUBBANDS_8

  SBC number of subbands 8

ESP_A2D_SBC_CIE_ALLOC_MTHD_SRN

  A2DP SBC allocation method bit mask in CIE.

  SBC allocation method SNR

ESP_A2D_SBC_CIE_ALLOC_MTHD_LOUDNESS

  SBC allocation method Loudness

ESP_A2D_CIE_LEN_SBC

ESP_A2D_CIE_LEN_M12

ESP_A2D_CIE_LEN_M24

ESP_A2D_CIE_LEN_ATRAC

### Type Definitions

typedef uint16_t esp_a2d_conn_hdl_t

  Connection handle, associate with specific device that connected

typedef uint8_t esp_a2d_mct_t

typedef uint16_t esp_a2d_psc_t

typedef void (*esp_a2d_cb_t)(esp_a2d_cb_event_t event, esp_a2d_cb_param_t *param)

  A2DP profile callback function type.

  Param event:

    : Event type

  Param param:

    : Pointer to callback parameter

typedef void (*esp_a2d_sink_audio_data_cb_t)(esp_a2d_conn_hdl_t conn_hdl, esp_a2d_audio_buff_t *audio_buf)

  A2DP sink data callback function.

  Param conn_hdl:

    [in] connection handle

  Param audio_buf:

    [in] pointer to the data received from A2DP source device, should be freed by calling esp_a2d_audio_buff_free

### Enumerations

enum esp_a2d_connection_state_t

  Bluetooth A2DP connection states.

  Values:

  enumerator ESP_A2D_CONNECTION_STATE_DISCONNECTED

    connection released

  enumerator ESP_A2D_CONNECTION_STATE_CONNECTING

    connecting remote device

  enumerator ESP_A2D_CONNECTION_STATE_CONNECTED

    connection established

  enumerator ESP_A2D_CONNECTION_STATE_DISCONNECTING

    disconnecting remote device

enum esp_a2d_disc_rsn_t

  Bluetooth A2DP disconnection reason.

  Values:

  enumerator ESP_A2D_DISC_RSN_NORMAL

    Finished disconnection that is initiated by local or remote device

  enumerator ESP_A2D_DISC_RSN_ABNORMAL

    Abnormal disconnection caused by signal loss

enum esp_a2d_audio_state_t

  Bluetooth A2DP datapath states.

  Values:

  enumerator ESP_A2D_AUDIO_STATE_SUSPEND

    audio stream datapath suspended by remote device

  enumerator ESP_A2D_AUDIO_STATE_STARTED

    audio stream datapath started

enum esp_a2d_media_ctrl_ack_t

  A2DP media control command acknowledgement code.

  Values:

  enumerator ESP_A2D_MEDIA_CTRL_ACK_SUCCESS

    media control command is acknowledged with success

  enumerator ESP_A2D_MEDIA_CTRL_ACK_FAILURE

    media control command is acknowledged with failure

  enumerator ESP_A2D_MEDIA_CTRL_ACK_BUSY

    media control command is rejected, as previous command is not yet acknowledged

enum esp_a2d_media_ctrl_t

  A2DP media control commands.

  Values:

  enumerator ESP_A2D_MEDIA_CTRL_NONE

    Not for application use, use inside stack only.

  enumerator ESP_A2D_MEDIA_CTRL_CHECK_SRC_RDY

    check whether AVDTP is connected, only used in A2DP source

  enumerator ESP_A2D_MEDIA_CTRL_START

    command to set up media transmission channel

  enumerator ESP_A2D_MEDIA_CTRL_SUSPEND

    command to suspend media transmission

enum esp_a2d_init_state_t

  Bluetooth A2DP Initiation states.

  Values:

  enumerator ESP_A2D_DEINIT_SUCCESS

    A2DP profile deinit successful event

  enumerator ESP_A2D_INIT_SUCCESS

    A2DP profile deinit successful event

enum esp_a2d_sep_reg_state_t

  Bluetooth A2DP SEP register states.

  Values:

  enumerator ESP_A2D_SEP_REG_SUCCESS

    A2DP stream endpoint register success

  enumerator ESP_A2D_SEP_REG_FAIL

    A2DP stream endpoint register generic fail

  enumerator ESP_A2D_SEP_REG_UNSUPPORTED

    A2DP stream endpoint register fail, unsupported codec type or param

  enumerator ESP_A2D_SEP_REG_INVALID_STATE

    A2DP stream endpoint register fail, invalid state

enum esp_a2d_set_delay_value_state_t

  Bluetooth A2DP set delay report value states.

  Values:

  enumerator ESP_A2D_SET_SUCCESS

    A2DP profile set delay report value successful

  enumerator ESP_A2D_SET_INVALID_PARAMS

    A2DP profile set delay report value is invalid parameter

enum esp_a2d_cb_event_t

  A2DP callback events.

  Values:

  enumerator ESP_A2D_CONNECTION_STATE_EVT

    connection state changed event

  enumerator ESP_A2D_AUDIO_STATE_EVT

    audio stream transmission state changed event

  enumerator ESP_A2D_AUDIO_CFG_EVT

    audio codec is configured

  enumerator ESP_A2D_MEDIA_CTRL_ACK_EVT

    acknowledge event in response to media control commands

  enumerator ESP_A2D_PROF_STATE_EVT

    indicate a2dp init&deinit complete

  enumerator ESP_A2D_SEP_REG_STATE_EVT

    indicate a2dp steam endpoint register status

  enumerator ESP_A2D_SNK_PSC_CFG_EVT

    protocol service capabilities configured，only used for A2DP SINK

  enumerator ESP_A2D_SNK_SET_DELAY_VALUE_EVT

    indicate a2dp sink set delay report value complete, only used for A2DP SINK

  enumerator ESP_A2D_SNK_GET_DELAY_VALUE_EVT

    indicate a2dp sink get delay report value complete, only used for A2DP SINK

  enumerator ESP_A2D_REPORT_SNK_DELAY_VALUE_EVT

    report delay value, only used for A2DP SRC

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