A2dp sink的初始化流程和A2dp 的初始化流程,基本一样,这里做简单分析.这里分析的android的版本是Android O.
我们先从service的启动说起吧.
下面 是启动的时候的log:
D/BluetoothAdapterService( 2029): setProfileServiceState() - Starting service com.android.bluetooth.a2dpsink.A2dpSinkService
01-01 08:00:22.042 D/A2dpSinkService( 2029): Received start request. Starting profile... 01-01 08:00:22.045 D/A2dpSinkService( 2029): start() 01-01 08:00:22.054 I/BluetoothA2dpSinkServiceJni( 2029): classInitNative: succeeds
我们看看 A2dpSinkService.java的start函数的实现:
protected boolean start() {
if (DBG) {
Log.d(TAG, "start()");
}
// Start the media browser service.
Intent startIntent = new Intent(this, A2dpMediaBrowserService.class);
startService(startIntent);//启动service
mStateMachine = A2dpSinkStateMachine.make(this, this);//启动状态机
setA2dpSinkService(this);//设置sA2dpSinkService = this
return true;
}
这里比较重要的地方就是 sink 状态机的启动,我们进一步看看:
static A2dpSinkStateMachine make(A2dpSinkService svc, Context context) {
Log.d("A2dpSinkStateMachine", "make");
A2dpSinkStateMachine a2dpSm = new A2dpSinkStateMachine(svc, context);//新建状态机
a2dpSm.start();
return a2dpSm;
}
我们看看这个类的构造函数实现:
static {
classInitNative();
}
private A2dpSinkStateMachine(A2dpSinkService svc, Context context) {
super("A2dpSinkStateMachine");
mService = svc;
mContext = context;
mAdapter = BluetoothAdapter.getDefaultAdapter();
initNative();//初始化
mDisconnected = new Disconnected();
mPending = new Pending();
mConnected = new Connected();
addState(mDisconnected);
addState(mPending);
addState(mConnected);
setInitialState(mDisconnected);
PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
mIntentBroadcastHandler = new IntentBroadcastHandler();
}
上面 主要做了初始化,然后 新建三个状态,然后设置初始状态.这里主要分析一下初始化相关的流程： classInitNative()和initNative()
我们先看前者：
private native static void classInitNative();
这是本地实现的函数,在com_android_bluetooth_a2dp_sink.cpp中:
static void classInitNative(JNIEnv* env, jclass clazz) {
method_onConnectionStateChanged =
env->GetMethodID(clazz, "onConnectionStateChanged", "(I[B)V");
method_onAudioStateChanged =
env->GetMethodID(clazz, "onAudioStateChanged", "(I[B)V");
method_onAudioConfigChanged =
env->GetMethodID(clazz, "onAudioConfigChanged", "([BII)V");
ALOGI("%s: succeeds", __func__);
}
主要就是 从上层 索取了一些函数调用的"句柄",我们继续看initNative:
static void initNative(JNIEnv* env, jobject object) {
const bt_interface_t* btInf = getBluetoothInterface();
if (btInf == NULL) {
ALOGE("Bluetooth module is not loaded");
return;
}
if (sBluetoothA2dpInterface != NULL) {
ALOGW("Cleaning up A2DP Interface before initializing...");
sBluetoothA2dpInterface->cleanup();
sBluetoothA2dpInterface = NULL;
}
if (mCallbacksObj != NULL) {
ALOGW("Cleaning up A2DP callback object");
env->DeleteGlobalRef(mCallbacksObj);
mCallbacksObj = NULL;
}
sBluetoothA2dpInterface =
(btav_sink_interface_t*)btInf->get_profile_interface(
BT_PROFILE_ADVANCED_AUDIO_SINK_ID);
if (sBluetoothA2dpInterface == NULL) {
ALOGE("Failed to get Bluetooth A2DP Sink Interface");
return;
}
bt_status_t status = sBluetoothA2dpInterface->init(&sBluetoothA2dpCallbacks);
if (status != BT_STATUS_SUCCESS) {
ALOGE("Failed to initialize Bluetooth A2DP Sink, status: %d", status);
sBluetoothA2dpInterface = NULL;
return;
}
mCallbacksObj = env->NewGlobalRef(object);
}
上面的逻辑 就是先获取蓝牙的接口,再获取sink 的接口,然后对sink 接口进行初始化.我们主要看初始化的过程:
实现是在btif_av.cc中:
static const btav_sink_interface_t bt_av_sink_interface = {
sizeof(btav_sink_interface_t),
init_sink,
sink_connect_src,
disconnect,
cleanup_sink,
update_audio_focus_state,
update_audio_track_gain,
}
这里的init 对应的接口就是init_sink,我们继续看:
/*******************************************************************************
*
* Function init_sink
*
* Description Initializes the AV interface for sink mode
*
* Returns bt_status_t
*
******************************************************************************/
static bt_status_t init_sink(btav_sink_callbacks_t* callbacks) {
BTIF_TRACE_EVENT("%s()", __func__);
bt_status_t status = btif_av_init(BTA_A2DP_SINK_SERVICE_ID);
if (status == BT_STATUS_SUCCESS) bt_av_sink_callbacks = callbacks;
return status;
}
这里的核心是btif_av_init,这里和之前src的初始化很相似,由于Android版本的演化,这里的btif_av_init 接口已经有了参数,:
/*******************************************************************************
*
* Function btif_av_init
*
* Description Initializes btif AV if not already done
*
* Returns bt_status_t
*
******************************************************************************/
bt_status_t btif_av_init(int service_id) {
if (btif_av_cb.sm_handle == NULL) {
alarm_free(av_open_on_rc_timer);
av_open_on_rc_timer = alarm_new("btif_av.av_open_on_rc_timer");
switch (service_id) {
case BTA_A2DP_SOURCE_SERVICE_ID:
if (!btif_a2dp_source_startup())
return BT_STATUS_FAIL; // Already running
break;
case BTA_A2DP_SINK_SERVICE_ID:
if (!btif_a2dp_sink_startup())
return BT_STATUS_FAIL; // Already running
break;
}
/* Also initialize the AV state machine */
btif_av_cb.sm_handle = btif_sm_init(
(const btif_sm_handler_t*)btif_av_state_handlers, BTIF_AV_STATE_IDLE);//初始化 av 状态机
btif_enable_service(service_id);//enable 某个service
}
return BT_STATUS_SUCCESS;
}
从上面的代码结构可以看出,此接口是sink 和src 共享的.
上面的代码的执行任务分为3个部分：
- btif—a2dp-sink的线程启动btif_sm_init
- btif_sm_init
- btif_enable_service(sink)
我们发现根据传入的参数不同，如果是src，那么执行btif_a2dp_source_startup，如果是sink 执行：btif_a2dp_sink_startup，看了下两者的实现也是大致相同，都是先设置相应的状态，然后新建线程，然后绑定线程队列，然后调用thread_post 去执行 剩下的流程：
bool btif_a2dp_sink_startup(void) {
if (btif_a2dp_sink_state != BTIF_A2DP_SINK_STATE_OFF) {
APPL_TRACE_ERROR("%s: A2DP Sink media task already running", __func__);//先判断状态机的状态
return false;
}
memset(&btif_a2dp_sink_cb, 0, sizeof(btif_a2dp_sink_cb));
btif_a2dp_sink_state = BTIF_A2DP_SINK_STATE_STARTING_UP;//设置状态机
APPL_TRACE_EVENT("## A2DP SINK START MEDIA THREAD ##");
/* Start A2DP Sink media task */
btif_a2dp_sink_cb.worker_thread = thread_new("btif_a2dp_sink_worker_thread");
...
btif_a2dp_sink_cb.rx_focus_state = BTIF_A2DP_SINK_FOCUS_NOT_GRANTED;
btif_a2dp_sink_cb.audio_track = NULL;
btif_a2dp_sink_cb.rx_audio_queue = fixed_queue_new(SIZE_MAX);//新建audio 队列
btif_a2dp_sink_cb.cmd_msg_queue = fixed_queue_new(SIZE_MAX);//新建cmd msg队列
fixed_queue_register_dequeue(
btif_a2dp_sink_cb.cmd_msg_queue,
thread_get_reactor(btif_a2dp_sink_cb.worker_thread),
btif_a2dp_sink_command_ready, NULL);绑定命令队列以及命令处理函数
APPL_TRACE_EVENT("## A2DP SINK MEDIA THREAD STARTED ##");
/* Schedule the rest of the startup operations */
thread_post(btif_a2dp_sink_cb.worker_thread, btif_a2dp_sink_startup_delayed,
NULL);//接下来的流程放置到btif_a2dp_sink_worker_thread的work_queue里面去
return true;
}
我们看看 btif_a2dp_sink_startup_delayed 的实现：
static void btif_a2dp_sink_startup_delayed(UNUSED_ATTR void* context) {
raise_priority_a2dp(TASK_HIGH_MEDIA);
btif_a2dp_sink_state = BTIF_A2DP_SINK_STATE_RUNNING;//更新sink的状态
}
下面我们看看btif_sm_init的实现：
这里是新建了一个状态机，为后续的状态转换作准备：该函数将会传入以下的参数，我们发现是一个个的处理handler
static const btif_sm_handler_t btif_av_state_handlers[] = {
btif_av_state_idle_handler, btif_av_state_opening_handler,
btif_av_state_opened_handler, btif_av_state_started_handler,
btif_av_state_closing_handler};
/*****************************************************************************
*
* Function btif_sm_init
*
* Description Initializes the state machine with the state handlers
* The caller should ensure that the table and the corresponding
* states match. The location that 'p_handlers' points to shall
* be available until the btif_sm_shutdown API is invoked.
*
* Returns Returns a pointer to the initialized state machine handle.
*
*****************************************************************************/
btif_sm_handle_t btif_sm_init(const btif_sm_handler_t* p_handlers,
btif_sm_state_t initial_state) {
btif_sm_cb_t* p_cb = (btif_sm_cb_t*)osi_malloc(sizeof(btif_sm_cb_t));
p_cb->state = initial_state;//设置初始状态
p_cb->p_handlers = (btif_sm_handler_t*)p_handlers;//将这个handler赋值到pcb里面
/* Send BTIF_SM_ENTER_EVT to the initial state */
p_cb->p_handlers[initial_state](BTIF_SM_ENTER_EVT, NULL);
return (btif_sm_handle_t)p_cb;
}
最后会执行 进如idle 的状态机的流程:这里不作具体分析了
static bool btif_av_state_idle_handler(btif_sm_event_t event, void* p_data) {
BTIF_TRACE_DEBUG("%s event:%s flags %x", __func__,
dump_av_sm_event_name((btif_av_sm_event_t)event),
btif_av_cb.flags);
switch (event) {
case BTIF_SM_ENTER_EVT:
/* clear the peer_bda */
memset(&btif_av_cb.peer_bda, 0, sizeof(bt_bdaddr_t));
btif_av_cb.flags = 0;
btif_av_cb.edr = 0;
bta_av_co_init(btif_av_cb.codec_priorities);
btif_a2dp_on_idle();
break;
下面我们在看看btif_enable_service 的流程:
/*******************************************************************************
*
* Function btif_enable_service
*
* Description Enables the service 'service_ID' to the service_mask.
* Upon BT enable, BTIF core shall invoke the BTA APIs to
* enable the profiles
*
* Returns bt_status_t
*
******************************************************************************/
bt_status_t btif_enable_service(tBTA_SERVICE_ID service_id) {
tBTA_SERVICE_ID* p_id = &service_id;
/* If BT is enabled, we need to switch to BTIF context and trigger the
* enable for that profile
*
* Otherwise, we just set the flag. On BT_Enable, the DM will trigger
* enable for the profiles that have been enabled */
btif_enabled_services |= (1 << service_id);//设置标志位
BTIF_TRACE_DEBUG("%s: current services:0x%x", __func__,
btif_enabled_services);
if (btif_is_enabled()) {
btif_transfer_context(btif_dm_execute_service_request,
BTIF_DM_ENABLE_SERVICE, (char*)p_id,
sizeof(tBTA_SERVICE_ID), NULL);//开启该profile
}
return BT_STATUS_SUCCESS;
}
我们需要开始的profile 隐藏在p_id 参数中,那我们也可以看出,这里其他的profile 也应该是走的这个流程.
void btif_dm_execute_service_request(uint16_t event, char* p_param) {
bool b_enable = false;
bt_status_t status;
if (event == BTIF_DM_ENABLE_SERVICE) {
b_enable = true;
}
status =
btif_in_execute_service_request(*((tBTA_SERVICE_ID*)p_param), b_enable);
if (status == BT_STATUS_SUCCESS) {
bt_property_t property;
bt_uuid_t local_uuids[BT_MAX_NUM_UUIDS];//新建内存存放uuid
/* Now send the UUID_PROPERTY_CHANGED event to the upper layer */
BTIF_STORAGE_FILL_PROPERTY(&property, BT_PROPERTY_UUIDS,
sizeof(local_uuids), local_uuids);//
btif_storage_get_adapter_property(&property);//fill property value
HAL_CBACK(bt_hal_cbacks, adapter_properties_cb, BT_STATUS_SUCCESS, 1,
&property);//上报相关的property
}
return;
}
我们知道当 profile启动完成之后,那么 将通过HAL_CBACK 将已经启动的property 上报到JNI 以及以上.
那么我们现在看看btif_in_execute_service_request的实现:
bt_status_t btif_in_execute_service_request(tBTA_SERVICE_ID service_id,
bool b_enable) {
BTIF_TRACE_DEBUG("%s service_id: %d", __func__, service_id);
/* Check the service_ID and invoke the profile's BT state changed API */
switch (service_id) {
case BTA_HFP_SERVICE_ID:
case BTA_HSP_SERVICE_ID: {
btif_hf_execute_service(b_enable);
} break;
case BTA_A2DP_SOURCE_SERVICE_ID: {
btif_av_execute_service(b_enable);
} break;
case BTA_A2DP_SINK_SERVICE_ID: {
btif_av_sink_execute_service(b_enable);
} break;
...
/*******************************************************************************
*
* Function btif_av_sink_execute_service
*
* Description Initializes/Shuts down the service
*
* Returns BT_STATUS_SUCCESS on success, BT_STATUS_FAIL otherwise
*
******************************************************************************/
bt_status_t btif_av_sink_execute_service(bool b_enable) {
if (b_enable) {
/* Added BTA_AV_FEAT_NO_SCO_SSPD - this ensures that the BTA does not
* auto-suspend av streaming on AG events(SCO or Call). The suspend shall
* be initiated by the app/audioflinger layers */
BTA_AvEnable(BTA_SEC_AUTHENTICATE,
BTA_AV_FEAT_NO_SCO_SSPD | BTA_AV_FEAT_RCCT |
BTA_AV_FEAT_METADATA | BTA_AV_FEAT_VENDOR |
BTA_AV_FEAT_ADV_CTRL | BTA_AV_FEAT_RCTG |
BTA_AV_FEAT_BROWSE,
bte_av_callback);
BTA_AvRegister(BTA_AV_CHNL_AUDIO, BTIF_AVK_SERVICE_NAME, 0,
bte_av_sink_media_callback, UUID_SERVCLASS_AUDIO_SINK);
} else {
BTA_AvDeregister(btif_av_cb.bta_handle);
BTA_AvDisable();
}
return BT_STATUS_SUCCESS;
}
这里和src的初始化的流程非常的相似,也是分为两个步骤:
-
BTA_AvEnable(BTA_SEC_AUTHENTICATE,BTA_AV_FEAT_NO_SCO_SSPD | BTA_AV_FEAT_RCCT |BTA_AV_FEAT_METADATA | BTA_AV_FEAT_VENDOR |BTA_AV_FEAT_ADV_CTRL | BTA_AV_FEAT_RCTG |
BTA_AV_FEAT_BROWSE,bte_av_callback); -
BTA_AvRegister(BTA_AV_CHNL_AUDIO, BTIF_AVK_SERVICE_NAME, 0,bte_av_sink_media_callback, UUID_SERVCLASS_AUDIO_SINK);
我们先看BTA_AvEnable :
#define BTA_SEC_AUTHENTICATE (BTM_SEC_IN_AUTHENTICATE | BTM_SEC_OUT_AUTHENTICATE) /* Authentication required. */0x12
#define BTM_SEC_IN_AUTHENTICATE 0x0002 #define BTM_SEC_OUT_AUTHENTICATE 0x0010
BTA_AV_FEAT_NO_SCO_SSPD | BTA_AV_FEAT_RCCT | BTA_AV_FEAT_METADATA | BTA_AV_FEAT_VENDOR | BTA_AV_FEAT_ADV_CTRL | BTA_AV_FEAT_RCTG | BTA_AV_FEAT_BROWSE,//0x825B
看看其回调函数:
static void bte_av_callback(tBTA_AV_EVT event, tBTA_AV* p_data) {
btif_transfer_context(btif_av_handle_event, event, (char*)p_data,
sizeof(tBTA_AV), btif_av_event_deep_copy);//基本上是把event 传给状态机
}
现在看看BTA_AvEnable的实现
/*******************************************************************************
*
* Function BTA_AvEnable
*
* Description Enable the advanced audio/video service. When the enable
* operation is complete the callback function will be
* called with a BTA_AV_ENABLE_EVT. This function must
* be called before other function in the AV API are
* called.
*
* Returns void
*
******************************************************************************/
void BTA_AvEnable(tBTA_SEC sec_mask, tBTA_AV_FEAT features,
tBTA_AV_CBACK* p_cback) {
tBTA_AV_API_ENABLE* p_buf =
(tBTA_AV_API_ENABLE*)osi_malloc(sizeof(tBTA_AV_API_ENABLE));
/* register with BTA system manager */
bta_sys_register(BTA_ID_AV, &bta_av_reg);
p_buf->hdr.event = BTA_AV_API_ENABLE_EVT;
p_buf->p_cback = p_cback;//bte_av_callback
p_buf->features = features;//0x825B
p_buf->sec_mask = sec_mask;//0x0012
bta_sys_sendmsg(p_buf);
}
发送了BTA_AV_API_ENABLE_EVT 这个事件；
#define BTA_ID_AV 18 /* Advanced audio/video */
这个 event的 主ID 还是BTA_ID_AV，而并不是BTA_ID_AVK
/* register with BTA system manager */ bta_sys_register(BTA_ID_AV, &bta_av_reg);
我们看看
static const tBTA_SYS_REG bta_av_reg = {bta_av_hdl_event, BTA_AvDisable};
也就是0x18开头的event 都是由bta_av_hdl_event 来统一处理：
/*******************************************************************************
*
* Function bta_av_hdl_event
*
* Description Advanced audio/video main event handling function.
*
*
* Returns bool
*
******************************************************************************/
bool bta_av_hdl_event(BT_HDR* p_msg) {
if (p_msg->event > BTA_AV_LAST_EVT) {
return true; /* to free p_msg */
}
if (p_msg->event >= BTA_AV_FIRST_NSM_EVT) {
APPL_TRACE_VERBOSE("%s: AV nsm event=0x%x(%s)", __func__, p_msg->event,
bta_av_evt_code(p_msg->event));
/* non state machine events */
(*bta_av_nsm_act[p_msg->event - BTA_AV_FIRST_NSM_EVT])(
(tBTA_AV_DATA*)p_msg);
} else if (p_msg->event >= BTA_AV_FIRST_SM_EVT &&
p_msg->event <= BTA_AV_LAST_SM_EVT) {
APPL_TRACE_VERBOSE("%s: AV sm event=0x%x(%s)", __func__, p_msg->event,
bta_av_evt_code(p_msg->event));
/* state machine events */
bta_av_sm_execute(&bta_av_cb, p_msg->event, (tBTA_AV_DATA*)p_msg);
} else {
APPL_TRACE_VERBOSE("handle=0x%x", p_msg->layer_specific);
/* stream state machine events */
bta_av_ssm_execute(bta_av_hndl_to_scb(p_msg->layer_specific), p_msg->event,
(tBTA_AV_DATA*)p_msg);
}
return true;
}
从上面的代码实现，我们发现 其讲event 分为了3类，一类是不在状态机中处理的，一类是在状态机中处理，还有一类是在stream 的状态机中处理的，现在我们将这些event 分类一下：
一以下是所有的event：
enum {
/* these events are handled by the AV main state machine */
BTA_AV_API_DISABLE_EVT = BTA_SYS_EVT_START(BTA_ID_AV),
BTA_AV_API_REMOTE_CMD_EVT,
BTA_AV_API_VENDOR_CMD_EVT,
BTA_AV_API_VENDOR_RSP_EVT,
BTA_AV_API_META_RSP_EVT,
BTA_AV_API_RC_CLOSE_EVT,
BTA_AV_AVRC_OPEN_EVT,
BTA_AV_AVRC_MSG_EVT,
BTA_AV_AVRC_NONE_EVT,
/* these events are handled by the AV stream state machine */
BTA_AV_API_OPEN_EVT,
BTA_AV_API_CLOSE_EVT,
BTA_AV_AP_START_EVT, /* the following 2 events must be in the same order as
the *API_*EVT */
BTA_AV_AP_STOP_EVT,
BTA_AV_API_RECONFIG_EVT,
BTA_AV_API_PROTECT_REQ_EVT,
BTA_AV_API_PROTECT_RSP_EVT,
BTA_AV_API_RC_OPEN_EVT,
BTA_AV_SRC_DATA_READY_EVT,
BTA_AV_CI_SETCONFIG_OK_EVT,
BTA_AV_CI_SETCONFIG_FAIL_EVT,
BTA_AV_SDP_DISC_OK_EVT,
BTA_AV_SDP_DISC_FAIL_EVT,
BTA_AV_STR_DISC_OK_EVT,
BTA_AV_STR_DISC_FAIL_EVT,
BTA_AV_STR_GETCAP_OK_EVT,
BTA_AV_STR_GETCAP_FAIL_EVT,
BTA_AV_STR_OPEN_OK_EVT,
BTA_AV_STR_OPEN_FAIL_EVT,
BTA_AV_STR_START_OK_EVT,
BTA_AV_STR_START_FAIL_EVT,
BTA_AV_STR_CLOSE_EVT,
BTA_AV_STR_CONFIG_IND_EVT,
BTA_AV_STR_SECURITY_IND_EVT,
BTA_AV_STR_SECURITY_CFM_EVT,
BTA_AV_STR_WRITE_CFM_EVT,
BTA_AV_STR_SUSPEND_CFM_EVT,
BTA_AV_STR_RECONFIG_CFM_EVT,
BTA_AV_AVRC_TIMER_EVT,
BTA_AV_AVDT_CONNECT_EVT,
BTA_AV_AVDT_DISCONNECT_EVT,
BTA_AV_ROLE_CHANGE_EVT,
BTA_AV_AVDT_DELAY_RPT_EVT,
BTA_AV_ACP_CONNECT_EVT,
BTA_AV_API_OFFLOAD_START_EVT,
BTA_AV_API_OFFLOAD_START_RSP_EVT,
/* these events are handled outside of the state machine */
BTA_AV_API_ENABLE_EVT,
BTA_AV_API_REGISTER_EVT,
BTA_AV_API_DEREGISTER_EVT,
BTA_AV_API_DISCONNECT_EVT,
BTA_AV_CI_SRC_DATA_READY_EVT,
BTA_AV_SIG_CHG_EVT,
BTA_AV_SIGNALLING_TIMER_EVT,
BTA_AV_SDP_AVRC_DISC_EVT,
BTA_AV_AVRC_CLOSE_EVT,
BTA_AV_AVRC_BROWSE_OPEN_EVT,
BTA_AV_AVRC_BROWSE_CLOSE_EVT,
BTA_AV_CONN_CHG_EVT,
BTA_AV_DEREG_COMP_EVT,
#if (AVDT_REPORTING == TRUE)
BTA_AV_AVDT_RPT_CONN_EVT,
#endif
BTA_AV_API_START_EVT, /* the following 2 events must be in the same order as
the *AP_*EVT */
BTA_AV_API_STOP_EVT
}
我们发现，不在状态机中处理的event是：
/* these events are handled outside of the state machine */
BTA_AV_API_ENABLE_EVT,
BTA_AV_API_REGISTER_EVT,
BTA_AV_API_DEREGISTER_EVT,
BTA_AV_API_DISCONNECT_EVT,
BTA_AV_CI_SRC_DATA_READY_EVT,
BTA_AV_SIG_CHG_EVT,
BTA_AV_SIGNALLING_TIMER_EVT,
BTA_AV_SDP_AVRC_DISC_EVT,
BTA_AV_AVRC_CLOSE_EVT,
BTA_AV_AVRC_BROWSE_OPEN_EVT,
BTA_AV_AVRC_BROWSE_CLOSE_EVT,
BTA_AV_CONN_CHG_EVT,
BTA_AV_DEREG_COMP_EVT,
#if (AVDT_REPORTING == TRUE)
BTA_AV_AVDT_RPT_CONN_EVT,
#endif
BTA_AV_API_START_EVT, /* the following 2 events must be in the same order as
the *AP_*EVT */
BTA_AV_API_STOP_EVT
处理他的函数是：bta_av_nsm_act：
/* action functions */
const tBTA_AV_NSM_ACT bta_av_nsm_act[] = {
bta_av_api_enable, /* BTA_AV_API_ENABLE_EVT */
bta_av_api_register, /* BTA_AV_API_REGISTER_EVT */
bta_av_api_deregister, /* BTA_AV_API_DEREGISTER_EVT */
bta_av_api_disconnect, /* BTA_AV_API_DISCONNECT_EVT */
bta_av_ci_data, /* BTA_AV_CI_SRC_DATA_READY_EVT */
bta_av_sig_chg, /* BTA_AV_SIG_CHG_EVT */
bta_av_signalling_timer, /* BTA_AV_SIGNALLING_TIMER_EVT */
bta_av_rc_disc_done, /* BTA_AV_SDP_AVRC_DISC_EVT */
bta_av_rc_closed, /* BTA_AV_AVRC_CLOSE_EVT */
bta_av_rc_browse_opened, /* BTA_AV_AVRC_BROWSE_OPEN_EVT */
bta_av_rc_browse_closed, /* BTA_AV_AVRC_BROWSE_CLOSE_EVT */
bta_av_conn_chg, /* BTA_AV_CONN_CHG_EVT */
bta_av_dereg_comp, /* BTA_AV_DEREG_COMP_EVT */
#if (AVDT_REPORTING == TRUE)
bta_av_rpc_conn, /* BTA_AV_AVDT_RPT_CONN_EVT */
#endif
bta_av_api_to_ssm, /* BTA_AV_API_START_EVT */
bta_av_api_to_ssm, /* BTA_AV_API_STOP_EVT */
}
还有一类事件 是在AV的main 的状态机中处理的：
/* these events are handled by the AV main state machine */ BTA_AV_API_DISABLE_EVT = BTA_SYS_EVT_START(BTA_ID_AV), BTA_AV_API_REMOTE_CMD_EVT, BTA_AV_API_VENDOR_CMD_EVT, BTA_AV_API_VENDOR_RSP_EVT, BTA_AV_API_META_RSP_EVT, BTA_AV_API_RC_CLOSE_EVT, BTA_AV_AVRC_OPEN_EVT, BTA_AV_AVRC_MSG_EVT, BTA_AV_AVRC_NONE_EVT,
处理的函数组是：bta_av_sm_execute --->bta_av_action:
/* action functions */
const tBTA_AV_ACTION bta_av_action[] = {
bta_av_disable,
bta_av_rc_opened,
bta_av_rc_remote_cmd,
bta_av_rc_vendor_cmd,
bta_av_rc_vendor_rsp,
bta_av_rc_free_rsp,
bta_av_rc_free_browse_msg,
bta_av_rc_meta_rsp,
bta_av_rc_msg,
bta_av_rc_close,
};
最后一类是 建立 stream之后的event：
/* these events are handled by the AV stream state machine */
BTA_AV_API_OPEN_EVT,
BTA_AV_API_CLOSE_EVT,
BTA_AV_AP_START_EVT, /* the following 2 events must be in the same order as
the *API_*EVT */
BTA_AV_AP_STOP_EVT,
BTA_AV_API_RECONFIG_EVT,
BTA_AV_API_PROTECT_REQ_EVT,
BTA_AV_API_PROTECT_RSP_EVT,
BTA_AV_API_RC_OPEN_EVT,
BTA_AV_SRC_DATA_READY_EVT,
BTA_AV_CI_SETCONFIG_OK_EVT,
BTA_AV_CI_SETCONFIG_FAIL_EVT,
BTA_AV_SDP_DISC_OK_EVT,
BTA_AV_SDP_DISC_FAIL_EVT,
BTA_AV_STR_DISC_OK_EVT,
BTA_AV_STR_DISC_FAIL_EVT,
BTA_AV_STR_GETCAP_OK_EVT,
BTA_AV_STR_GETCAP_FAIL_EVT,
BTA_AV_STR_OPEN_OK_EVT,
BTA_AV_STR_OPEN_FAIL_EVT,
BTA_AV_STR_START_OK_EVT,
BTA_AV_STR_START_FAIL_EVT,
BTA_AV_STR_CLOSE_EVT,
BTA_AV_STR_CONFIG_IND_EVT,
BTA_AV_STR_SECURITY_IND_EVT,
BTA_AV_STR_SECURITY_CFM_EVT,
BTA_AV_STR_WRITE_CFM_EVT,
BTA_AV_STR_SUSPEND_CFM_EVT,
BTA_AV_STR_RECONFIG_CFM_EVT,
BTA_AV_AVRC_TIMER_EVT,
BTA_AV_AVDT_CONNECT_EVT,
BTA_AV_AVDT_DISCONNECT_EVT,
BTA_AV_ROLE_CHANGE_EVT,
BTA_AV_AVDT_DELAY_RPT_EVT,
BTA_AV_ACP_CONNECT_EVT,
BTA_AV_API_OFFLOAD_START_EVT,
BTA_AV_API_OFFLOAD_START_RSP_EVT,
处理的函数是bta_av_ssm_execute ，处理的action 是p_scb->p_act_tbl
我们继续看BTA_AV_API_ENABLE_EVT 的处理，根据上面的分类，处理的函数是bta_av_api_enable：
/*******************************************************************************
*
* Function bta_av_api_enable
*
* Description Handle an API enable event.
*
*
* Returns void
*
******************************************************************************/
static void bta_av_api_enable(tBTA_AV_DATA* p_data) {
/* initialize control block */
memset(&bta_av_cb, 0, sizeof(tBTA_AV_CB));
for (int i = 0; i < BTA_AV_NUM_RCB; i++)
bta_av_cb.rcb[i].handle = BTA_AV_RC_HANDLE_NONE;
bta_av_cb.rc_acp_handle = BTA_AV_RC_HANDLE_NONE;
/*
* TODO: The "disable" event handling is missing - there we need
* to alarm_free() the alarms below.
*/
bta_av_cb.link_signalling_timer = alarm_new("bta_av.link_signalling_timer");//这里只是新建了一个timer ，还没有启动
bta_av_cb.accept_signalling_timer =
alarm_new("bta_av.accept_signalling_timer");
/* store parameters */
bta_av_cb.p_cback = p_data->api_enable.p_cback;//bte_av_callback
bta_av_cb.features = p_data->api_enable.features;//0x825B
bta_av_cb.sec_mask = p_data->api_enable.sec_mask;//0x0012
tBTA_AV_ENABLE enable;
enable.features = bta_av_cb.features;//0x825B
/* Register for SCO change event */
if (!(bta_av_cb.features & BTA_AV_FEAT_NO_SCO_SSPD)) {
bta_sys_sco_register(bta_av_sco_chg_cback);
}
/* call callback with enable event */
(*bta_av_cb.p_cback)(BTA_AV_ENABLE_EVT, (tBTA_AV*)&enable);//callback:bte_av_callback
}
这里需要注意的是 上面只是新建了定时器，还么有 启动定时器，我们看看回调函数的实现：
static void bte_av_callback(tBTA_AV_EVT event, tBTA_AV* p_data) {
btif_transfer_context(btif_av_handle_event, event, (char*)p_data,
sizeof(tBTA_AV), btif_av_event_deep_copy);
}
static void btif_av_handle_event(uint16_t event, char* p_param) {
BTIF_TRACE_EVENT("%s event:%s", __func__,
dump_av_sm_event_name((btif_av_sm_event_t)event));
switch (event) {
case BTIF_AV_CLEANUP_REQ_EVT:
btif_a2dp_source_shutdown();
btif_a2dp_sink_shutdown();
break;
case BTA_AV_REGISTER_EVT:
if (btif_av_cb.sm_handle == NULL) {
btif_av_cb.bta_handle = ((tBTA_AV*)p_param)->registr.hndl;
BTIF_TRACE_DEBUG("%s: BTA AV Handle updated", __func__);
}
/* FALLTHROUGH */
default:
btif_sm_dispatch(btif_av_cb.sm_handle, event, (void*)p_param);
btif_av_event_free_data(event, p_param);
}
}
上面走到到了 btif_sm_dispatch 里面了：
/*****************************************************************************
*
* Function btif_sm_dispatch
*
* Description Dispatches the 'event' along with 'data' to the current state
* handler
*
* Returns BT_STATUS_SUCCESS on success
* BT_STATUS_UNHANDLED if event was not processed
* BT_STATUS_FAIL otherwise
*
*****************************************************************************/
bt_status_t btif_sm_dispatch(btif_sm_handle_t handle, btif_sm_event_t event,
void* data) {
bt_status_t status = BT_STATUS_SUCCESS;
btif_sm_cb_t* p_cb = (btif_sm_cb_t*)handle;
if (p_cb == NULL) {
BTIF_TRACE_ERROR("%s : Invalid handle", __func__);
return BT_STATUS_FAIL;
}
if (p_cb->p_handlers[p_cb->state](event, data) == false)
return BT_STATUS_UNHANDLED;
return status;
}
这里的state 还是idle 状态， 这里发现 对于这个BTA_AV_ENABLE_EVT 并么有处理，这里就不分析。（和src的分析的流程基本一致）
下面继续看看BTA_AvRegister(BTA_AV_CHNL_AUDIO, BTIF_AVK_SERVICE_NAME, 0,bte_av_sink_media_callback, UUID_SERVCLASS_AUDIO_SINK);的实现：
这里和之前的src的分析不同点在于（Android版本不同）这里的参数个数多了一个，这里会传入了一个参数，标志是src还是sink 进行的注册。
/*******************************************************************************
*
* Function BTA_AvRegister
*
* Description Register the audio or video service to stack. When the
* operation is complete the callback function will be
* called with a BTA_AV_REGISTER_EVT. This function must
* be called before AVDT stream is open.
*
*
* Returns void
*
******************************************************************************/
void BTA_AvRegister(tBTA_AV_CHNL chnl, const char* p_service_name,
uint8_t app_id, tBTA_AV_SINK_DATA_CBACK* p_sink_data_cback,
uint16_t service_uuid) {
tBTA_AV_API_REG* p_buf =
(tBTA_AV_API_REG*)osi_malloc(sizeof(tBTA_AV_API_REG));
p_buf->hdr.layer_specific = chnl;//BTA_AV_CHNL_AUDIO = 0x40
p_buf->hdr.event = BTA_AV_API_REGISTER_EVT;
if (p_service_name)
strlcpy(p_buf->p_service_name, p_service_name, BTA_SERVICE_NAME_LEN);
else
p_buf->p_service_name[0] = 0;
p_buf->app_id = app_id;//0
p_buf->p_app_sink_data_cback = p_sink_data_cback;//bte_av_sink_media_callback
p_buf->service_uuid = service_uuid;//UUID_SERVCLASS_AUDIO_SINK = 0x110B
bta_sys_sendmsg(p_buf);
}
我们继续看这个event 的处理，我们发现bta_av_api_register 这个函数也是 sink 和src 共用的，这也是和Android6.0的实现不同的地方。
其实可以仿照AndroidO的代码去修改AndroidM的代码，以此将sink 和src 分开。
/*******************************************************************************
*
* Function bta_av_api_register
*
* Description allocate stream control block,
* register the service to stack
* create SDP record
*
* Returns void
*
******************************************************************************/
static void bta_av_api_register(tBTA_AV_DATA* p_data) {
tBTA_AV_REGISTER registr;
tBTA_AV_SCB* p_scb; /* stream control block */
tAVDT_REG reg;
tAVDT_CS cs;
char* p_service_name;
tBTA_UTL_COD cod;
memset(&cs, 0, sizeof(tAVDT_CS));//初始化cs，该项最终拷贝到p_scb->cfg，并且AVDT_CreateStream 会使用到
registr.status = BTA_AV_FAIL_RESOURCES;//register 记录注册的信息，回调的时候会上报
registr.app_id = p_data->api_reg.app_id;//0
registr.chnl = (tBTA_AV_CHNL)p_data->hdr.layer_specific;//layer_specific = 0x40
uint16_t profile_initialized = p_data->api_reg.service_uuid;//sink
if (profile_initialized == UUID_SERVCLASS_AUDIO_SINK) {
p_bta_av_cfg = (tBTA_AV_CFG*)&bta_avk_cfg;
} else if (profile_initialized == UUID_SERVCLASS_AUDIO_SOURCE) {
p_bta_av_cfg = (tBTA_AV_CFG*)&bta_av_cfg;
}
do {
p_scb = bta_av_alloc_scb(registr.chnl);//分配了一个 stream control block ：bta_av_cb.p_scb[xx] = p_scb
registr.hndl = p_scb->hndl;//0x41 or 0x42 --- hndl = (tBTA_AV_HNDL)((xx + 1) | chnl);
p_scb->app_id = registr.app_id;
/* initialize the stream control block */
registr.status = BTA_AV_SUCCESS;
if ((bta_av_cb.reg_audio + bta_av_cb.reg_video) == 0) {
/* the first channel registered. register to AVDTP */
reg.ctrl_mtu = p_bta_av_cfg->sig_mtu;
reg.ret_tout = BTA_AV_RET_TOUT;
reg.sig_tout = BTA_AV_SIG_TOUT;
reg.idle_tout = BTA_AV_IDLE_TOUT;
reg.sec_mask = bta_av_cb.sec_mask;
bta_ar_reg_avdt(®, bta_av_conn_cback, BTA_ID_AV);//注册到AVDT
bta_sys_role_chg_register(&bta_av_sys_rs_cback);
/* create remote control TG service if required */
if (bta_av_cb.features & (BTA_AV_FEAT_RCTG)) {
/* register with no authorization; let AVDTP use authorization instead */
bta_ar_reg_avct(p_bta_av_cfg->avrc_mtu, p_bta_av_cfg->avrc_br_mtu,
(uint8_t)(bta_av_cb.sec_mask & (~BTA_SEC_AUTHORIZE)),
BTA_ID_AV);
/* For the Audio Sink role we support additional TG 1.3 to support
* absolute volume.
*/
uint16_t profile_version = AVRC_REV_1_0;
if (profile_initialized == UUID_SERVCLASS_AUDIO_SOURCE) {
...
} else if (profile_initialized == UUID_SERVCLASS_AUDIO_SINK) {
// Initialize AVRCP1.4 to provide Absolute Volume control.
profile_version = AVRC_REV_1_4;
}
bta_ar_reg_avrc(
UUID_SERVCLASS_AV_REM_CTRL_TARGET, "AV Remote Control Target", NULL,
p_bta_av_cfg->avrc_tg_cat, BTA_ID_AV,
(bta_av_cb.features & BTA_AV_FEAT_BROWSE), profile_version);
#endif
}
/* Set the Capturing service class bit */
if (profile_initialized == UUID_SERVCLASS_AUDIO_SOURCE)
cod.service = BTM_COD_SERVICE_CAPTURING;
else if (profile_initialized == UUID_SERVCLASS_AUDIO_SINK)
cod.service = BTM_COD_SERVICE_RENDERING;
utl_set_device_class(&cod, BTA_UTL_SET_COD_SERVICE_CLASS);
} /* if 1st channel */
/* get stream configuration and create stream */
cs.cfg.num_codec = 1;
cs.nsc_mask =
AVDT_NSC_RECONFIG |
((bta_av_cb.features & BTA_AV_FEAT_PROTECT) ? 0 : AVDT_NSC_SECURITY);
APPL_TRACE_DEBUG("nsc_mask: 0x%x", cs.nsc_mask);
if (p_data->api_reg.p_service_name[0] == 0) {
p_service_name = NULL;
} else {
p_service_name = p_data->api_reg.p_service_name;//用于后面创建SDP record
}
p_scb->suspend_sup = true;
p_scb->recfg_sup = true;
p_scb->skip_sdp = false;
cs.p_ctrl_cback = bta_av_dt_cback[p_scb->hdi];
if (registr.chnl == BTA_AV_CHNL_AUDIO) {//填充p_scb
/* set up the audio stream control block */
p_scb->p_act_tbl = (const tBTA_AV_ACT*)bta_av_a2dp_action;
p_scb->p_cos = &bta_av_a2dp_cos;
p_scb->media_type = AVDT_MEDIA_TYPE_AUDIO;
cs.cfg.psc_mask = AVDT_PSC_TRANS;
cs.media_type = AVDT_MEDIA_TYPE_AUDIO;
cs.mtu = p_bta_av_cfg->audio_mtu;
cs.flush_to = L2CAP_DEFAULT_FLUSH_TO;
btav_a2dp_codec_index_t codec_index_min =
BTAV_A2DP_CODEC_INDEX_SOURCE_MIN;
btav_a2dp_codec_index_t codec_index_max =
BTAV_A2DP_CODEC_INDEX_SOURCE_MAX;
if (profile_initialized == UUID_SERVCLASS_AUDIO_SOURCE) {
...
} else if (profile_initialized == UUID_SERVCLASS_AUDIO_SINK) {
cs.tsep = AVDT_TSEP_SNK;
cs.p_sink_data_cback = bta_av_sink_data_cback;
codec_index_min = BTAV_A2DP_CODEC_INDEX_SINK_MIN;
codec_index_max = BTAV_A2DP_CODEC_INDEX_SINK_MAX;
}
/* Initialize handles to zero */
for (int xx = 0; xx < BTAV_A2DP_CODEC_INDEX_MAX; xx++) {
p_scb->seps[xx].av_handle = 0;
}
/* keep the configuration in the stream control block */
memcpy(&p_scb->cfg, &cs.cfg, sizeof(tAVDT_CFG));
for (int i = codec_index_min; i < codec_index_max; i++) {
btav_a2dp_codec_index_t codec_index =
static_cast<btav_a2dp_codec_index_t>(i);
if (!(*bta_av_a2dp_cos.init)(codec_index, &cs.cfg)) {
continue;
}
if (AVDT_CreateStream(&p_scb->seps[codec_index].av_handle, &cs) !=
AVDT_SUCCESS) {
continue;
}
/* Save a copy of the codec */
memcpy(p_scb->seps[codec_index].codec_info, cs.cfg.codec_info,
AVDT_CODEC_SIZE);
p_scb->seps[codec_index].tsep = cs.tsep;
if (cs.tsep == AVDT_TSEP_SNK) {
p_scb->seps[codec_index].p_app_sink_data_cback =
p_data->api_reg.p_app_sink_data_cback;
} else {
/* In case of A2DP SOURCE we don't need a callback to
* handle media packets.
*/
p_scb->seps[codec_index].p_app_sink_data_cback = NULL;
}
}
if (!bta_av_cb.reg_audio) {
bta_av_cb.sdp_a2dp_handle = 0;
bta_av_cb.sdp_a2dp_snk_handle = 0;
if (profile_initialized == UUID_SERVCLASS_AUDIO_SOURCE) {
...
} else if (profile_initialized == UUID_SERVCLASS_AUDIO_SINK) {
#if (BTA_AV_SINK_INCLUDED == TRUE)
bta_av_cb.sdp_a2dp_snk_handle = SDP_CreateRecord();
A2DP_AddRecord(UUID_SERVCLASS_AUDIO_SINK, p_service_name, NULL,
A2DP_SUPF_PLAYER, bta_av_cb.sdp_a2dp_snk_handle);
bta_sys_add_uuid(UUID_SERVCLASS_AUDIO_SINK);
#endif
}
/* start listening when A2DP is registered */
if (bta_av_cb.features & BTA_AV_FEAT_RCTG)
bta_av_rc_create(&bta_av_cb, AVCT_ACP, 0, BTA_AV_NUM_LINKS + 1);
/* if the AV and AVK are both supported, it cannot support the CT role
*/
if (bta_av_cb.features & (BTA_AV_FEAT_RCCT)) {
/* create an SDP record as AVRC CT. We create 1.3 for SOURCE
* because we rely on feature bits being scanned by external
* devices more than the profile version itself.
*
* We create 1.4 for SINK since we support browsing.
*/
if (profile_initialized == UUID_SERVCLASS_AUDIO_SOURCE) {
...
} else if (profile_initialized == UUID_SERVCLASS_AUDIO_SINK) {
bta_ar_reg_avrc(UUID_SERVCLASS_AV_REMOTE_CONTROL, NULL, NULL,
p_bta_av_cfg->avrc_ct_cat, BTA_ID_AV,
(bta_av_cb.features & BTA_AV_FEAT_BROWSE),
AVRC_REV_1_6);
}
}
}
bta_av_cb.reg_audio |= BTA_AV_HNDL_TO_MSK(p_scb->hdi);
APPL_TRACE_DEBUG("reg_audio: 0x%x", bta_av_cb.reg_audio);
}
} while (0);
/* call callback with register event */
(*bta_av_cb.p_cback)(BTA_AV_REGISTER_EVT, (tBTA_AV*)®istr);
}
上面注册的内容和 a2dp 初始化的流程基本相同，不作具体分析。
关于a2dp sink的初始化的流程，就分析到这里了。
来源：https://www.cnblogs.com/libs-liu/p/9541160.html