android 蓝牙hfp server实现简介

最新推荐文章于 2024-11-16 19:46:54 发布

原创最新推荐文章于 2024-11-16 19:46:54 发布 · 1.9k 阅读

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本文介绍了如何在蓝牙HFP（Hands-Free Profile）1.6版本中实现语音识别功能，包括配置文件设置、底层实现原理及Java层回调机制，并详细说明了通过发送AT+BVRA命令激活语音识别的过程。

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首先确认配置文件是否开启hfp profile功能。根据设备的角色（hfp client / hfp server）来配置hfp profile.
profile 配置文件路径：
alps/packages/apps/Bluetooth/res/values/config.xml
alps/device/${customer}/${ProjectName}/overlay/packages/apps/Bluetooth/res/values/config.xml

e.g. 设备的角色定义为hfp server,需做如下配置：
<bool name="profile_supported_hs_hfp">true</bool>

<bool name="profile_supported_hfpclient">false</bool>

接下来介绍hfp server的实现，以通过蓝牙耳机激活语音识别为例。hfp1.6 版本已经支持了语音识别的实现。

//HF通过发送AT+BVRA命令给AG来发起激活语音识别应用。语音识别应用安装在AG中。

除了audio的路由、语音识别的激活控制等功能需要用到蓝牙功能，其余都依赖于语音识别应用的实现。

//AG 中的bt stack收到hf发过来的cmd AT+BVRA,调用回调函数处理

external/bluetooth/bluedroid/btif/src/btif_hf.c

static void btif_hf_upstreams_evt(UINT16 event, char* p_param){

.....

case BTA_AG_AT_BVRA_EVT:
HAL_CBACK(bt_hf_callbacks, vr_cmd_cb,
(p_data->val.num == 1) ? BTHF_VR_STATE_STARTED :
BTHF_VR_STATE_STOPPED, &btif_hf_cb[idx].connected_bda);
break;

}

//java层的hfp service在初始化的时候，注册回调

packages/apps/Bluetooth/jni/com_android_bluetooth_hfp.cpp

static bthf_callbacks_t sBluetoothHfpCallbacks = {
sizeof(sBluetoothHfpCallbacks),
connection_state_callback,
audio_state_callback,
voice_recognition_callback,
answer_call_callback,
hangup_call_callback,
volume_control_callback,
dial_call_callback,
dtmf_cmd_callback,
noice_reduction_callback,
wbs_callback,
at_chld_callback,
at_cnum_callback,
at_cind_callback,
at_cops_callback,
at_clcc_callback,
unknown_at_callback,
key_pressed_callback
};

packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetStateMachine.java

private HeadsetStateMachine(HeadsetService context) {

......

initializeNative(max_hf_connections);

}

packages/apps/Bluetooth/jni/com_android_bluetooth_hfp.cpp

initializeNative（）{

......

if ( (status = sBluetoothHfpInterface->init(&sBluetoothHfpCallbacks,
max_hf_clients)) != BT_STATUS_SUCCESS) {
ALOGE("Failed to initialize Bluetooth HFP, status: %d", status);
sBluetoothHfpInterface = NULL;
return;
}

}

external/bluetooth/bluedroid/btif/src/btif_hf.c

static bt_status_t init( bthf_callbacks_t* callbacks, int max_hf_clients){

......

bt_hf_callbacks = callbacks;

}

//回调函数（ e.g. voice_recognition_callback）首先通过JNI 调用到java中的函数(onVrStateChanged)

static void voice_recognition_callback(bthf_vr_state_t state, bt_bdaddr_t* bd_addr) {
......
sCallbackEnv->SetByteArrayRegion(addr, 0, sizeof(bt_bdaddr_t), (jbyte *) bd_addr);
sCallbackEnv->CallVoidMethod(mCallbacksObj, method_onVrStateChanged, (jint) state, addr);
checkAndClearExceptionFromCallback(sCallbackEnv, __FUNCTION__);
sCallbackEnv->DeleteLocalRef(addr);
}

packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetStateMachine.java

private void onVrStateChanged(int state, byte[] address) {
StackEvent event = new StackEvent(EVENT_TYPE_VR_STATE_CHANGED);
event.valueInt = state;
event.device = getDevice(address);
sendMessage(STACK_EVENT, event);
}

//java中通过发送intent携带action的方式启动语音识别的app

private void processVrEvent(int state, BluetoothDevice device) {

.....

mService.startActivity(sVoiceCommandIntent);

}

HeadsetStateMachine（）{

......

if (sVoiceCommandIntent == null) {
sVoiceCommandIntent = new Intent(Intent.ACTION_VOICE_COMMAND);
sVoiceCommandIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
}

}