A2dp sink 初始化流程源码分析
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。
