本文主要是介绍android audio音量控制流程，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
Audio java部分代码流程(4.1.2 version)：
在frameworks/base/media/java/android/media中：IAudioService.aidl提供了所有对外的接口函数，如下：
- interface IAudioService {
- void adjustVolume(int direction, int flags);
- void adjustSuggestedStreamVolume(int direction, int suggestedStreamType, int flags);
- void adjustStreamVolume(int streamType, int direction, int flags);
- void setStreamVolume(int streamType, int index, int flags);
- void setStreamSolo(int streamType, boolean state, IBinder cb);
- void setStreamMute(int streamType, boolean state, IBinder cb);
- boolean isStreamMute(int streamType);
- int getStreamVolume(int streamType);
- int getStreamMaxVolume(int streamType);
- int getLastAudibleStreamVolume(int streamType);
- void setRingerMode(int ringerMode);
- .......................
- }
- public class AudioService extends IAudioService.Stub {
- ........
- }
- 492 try {
- 493 Slog.i(TAG, "Audio Service");
- 494 ServiceManager.addService(Context.AUDIO_SERVICE, new AudioService(context));
- 495 } catch (Throwable e) {
- 496 reportWtf("starting Audio Service", e);
- 497 }
而AudioManager.java则实现这些函数了对外应用的接口，比如：
- 496 public void adjustVolume(int direction, int flags) {
- 497 IAudioService service = getService(); //
- 498 try {
- 499 service.adjustVolume(direction, flags);
- 500 } catch (RemoteException e) {
- 501 Log.e(TAG, "Dead object in adjustVolume", e);
- 502 }
- 503 }
- 365 private static IAudioService getService()
- 366 {
- 367 if (sService != null) {
- 368 return sService;
- 369 }
- 370 IBinder b = ServiceManager.getService(Context.AUDIO_SERVICE);
- 371 sService = IAudioService.Stub.asInterface(b);
- 372 return sService;
- 373 }
- 281 registerService(AUDIO_SERVICE, new ServiceFetcher() {
- 282 public Object createService(ContextImpl ctx) {
- 283 return new AudioManager(ctx);
- 284 }});
- 10353 public class AudioManager {
- 10354 method public int abandonAudioFocus(android.media.AudioManager.OnAudioFocusChangeListener);
- 10355 method public void adjustStreamVolume(int, int, int);
- 10356 method public void adjustSuggestedStreamVolume(int, int, int);
- 10357 method public void adjustVolume(int, int);
- 10358 method public int getMode();
- 10359 method public java.lang.String getParameters(java.lang.String);
- 10360 method public int getRingerMode();
- 10361 method public deprecated int getRouting(int);
- 10362 method public int getStreamMaxVolume(int);
- 10363 method public int getStreamVolume(int);
- 10364 method public int getVibrateSetting(int);
- 10365 method public boolean isBluetoothA2dpOn();
然后看看比如setStreamVolume是如何从java调用到底层的：
1、应用调用比如mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0);
2、AudioManager.java调用public void setStreamVolume(int streamType, int index, int flags){};
3、AudioService.java调用public void setStreamVolume(int streamType, int index, int flags){},在该函数中调用
setStreamVolumeInt(mStreamVolumeAlias[streamType], 831 index, 832 device, 833 false, 834 true);
---------> 1002 sendMsg(mAudioHandler, 1003 MSG_PERSIST_VOLUME, 1004 SENDMSG_QUEUE, 1005 PERSIST_LAST_AUDIBLE, 1006 device, 1007 streamState, 1008 PERSIST_DELAY); 而mAudioHandler = new AudioHandler()，看看这个AudioHandler类:private class AudioHandler extends Handler {};-------->
所以调用该类重写的handleMessage方法--------->
- 2940 @Override
- 2941 public void handleMessage(Message msg) {
- 2942
- 2943 switch (msg.what) {
- 2944
- 2945 case MSG_SET_DEVICE_VOLUME:
- 2946 setDeviceVolume((VolumeStreamState) msg.obj, msg.arg1);
- 2947 break;
AudioSystem.setStreamVolumeIndex--------->
setStreamVolumeIndex的定义在AudioSystem.java中-------->public static native int setStreamVolumeIndex(int stream, int index, int device);
setStreamVolumeIndex的JNI实现在base/core/jni/android_media_AudioSystem.cpp中---------->
- 178 static int
- 179 android_media_AudioSystem_setStreamVolumeIndex(JNIEnv *env,
- 180 jobject thiz,
- 181 jint stream,
- 182 jint index,
- 183 jint device)
- 184 {
- 185 return check_AudioSystem_Command(
- 186 AudioSystem::setStreamVolumeIndex(static_cast <audio_stream_type_t>(stream),
- 187 index,
- 188 (audio_devices_t)device));
- 189 }
- 666 status_t AudioSystem::setStreamVolumeIndex(audio_stream_type_t stream,
- 667 int index,
- 668 audio_devices_t device)
- 669 {
- 670 const sp<IAudioPolicyService>& aps = AudioSystem::get_audio_policy_service();
- 671 if (aps == 0) return PERMISSION_DENIED;
- 672 return aps->setStreamVolumeIndex(stream, index, device);
- 673 }
- 514 const sp<IAudioPolicyService>& AudioSystem::get_audio_policy_service()
- 515 {
- 516 gLock.lock();
- 517 if (gAudioPolicyService == 0) {
- 518 sp<IServiceManager> sm = defaultServiceManager();//取得BpServiceManager，通过这个代理可以调用BnServiceManager::onTransact，最后和
- //ServiceManager通讯
- 519 sp<IBinder> binder;
- 520 do {
- 521 binder = sm->getService(String16("media.audio_policy"));//从ServiceManager获得远程AudioPolicyService的句柄
- 522 if (binder != 0)
- 523 break;
- 524 ALOGW("AudioPolicyService not published, waiting...");
- 525 usleep(500000); // 0.5 s
- 526 } while (true);
- 527 if (gAudioPolicyServiceClient == NULL) {
- 528 gAudioPolicyServiceClient = new AudioPolicyServiceClient();
- 529 }
- 530 binder->linkToDeath(gAudioPolicyServiceClient);
- 531 gAudioPolicyService = interface_cast<IAudioPolicyService>(binder);
- 532 gLock.unlock();
- 533 } else {
- 534 gLock.unlock();
- 535 }
- 536 return gAudioPolicyService;
- 537 }
- 42 inline sp<INTERFACE> interface_cast(const sp<IBinder>&obj)
- 43 {
- 44 return INTERFACE::asInterface(obj);
- 45 }
- DECLARE_META_INTERFACE(AudioPolicyService)展开后得到的，DECLARE_META_INTERFACE定义在IInterface.h中:
- 74 #define DECLARE_META_INTERFACE(INTERFACE) \
- 75 static const android::String16 descriptor; \
- 76 static android::sp<I##INTERFACE> asInterface( \
- 77 const android::sp<android::IBinder>& obj); \
- 78 virtual const android::String16& getInterfaceDescriptor() const; \
- 79 I##INTERFACE(); \
- 80 virtual ~I##INTERFACE();
- #define IMPLEMENT_META_INTERFACE(INTERFACE, NAME)
- ........................
- 89 android::sp<I##INTERFACE> I##INTERFACE::asInterface( \
- 90 const android::sp<android::IBinder>& obj) \
- 91 { \
- 92 android::sp<I##INTERFACE> intr; \
- 93 if (obj != NULL) { \
- 94 intr = static_cast<I##INTERFACE*>( \
- 95 obj->queryLocalInterface( \
- 96 I##INTERFACE::descriptor).get()); \
- 97 if (intr == NULL) { \
- 98 intr = new Bp##INTERFACE(obj); \
- 99 } \
- 100 } \
- 101 return intr; \
- 102 }
展开后最终是生成调用new BpAudioPolicyService(new BpBinder(handle)),这里的handle是一个句柄;这样我们最终得到了AudioPolicyService的代理BpAudioPolicyService，通过它就可以和
AudioPolicyService的本地接口BnAudioPolicyService通讯了
回到前面的AudioSystem.cpp，取得代理BpAudioPolicyService后调用aps->setStreamVolumeIndex，所以进入IAudioPolicyService.cpp：
class BpAudioPolicyService : public BpInterface<IAudioPolicyService>:
- 233 virtual status_t setStreamVolumeIndex(audio_stream_type_t stream,
- 234 int index,
- 235 audio_devices_t device)
- 236 {
- 237 Parcel data, reply;
- 238 data.writeInterfaceToken(IAudioPolicyService::getInterfaceDescriptor());
- 239 data.writeInt32(static_cast <uint32_t>(stream));
- 240 data.writeInt32(index);
- 241 data.writeInt32(static_cast <uint32_t>(device));
- 242 remote()->transact(SET_STREAM_VOLUME, data, &reply);
- 243 return static_cast <status_t> (reply.readInt32());
- 244 }
- inline IBinder* remote() { return mRemote; }
- IBinder* const mRemote;
存映射了空间),所以调用BpBinder.cpp的transact函数：
- 159 status_t BpBinder::transact(
- 160 uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
- 161 {
- 162 // Once a binder has died, it will never come back to life.
- 163 if (mAlive) {
- 164 status_t status = IPCThreadState::self()->transact(
- 165 mHandle, code, data, reply, flags);
- 166 if (status == DEAD_OBJECT) mAlive = 0;
- 167 return status;
- 168 }
- 169
- 170 return DEAD_OBJECT;
- 171 }
程，binder驱动将数据拷贝到service的内存共享空间，并告诉service这个内核空间相对用户空间的偏移，远程服务端就可以不用再次拷贝数据，直接从用户空间就可以读取数据了， 这样remote()->transact(SET_STREAM_VOLUME, data, &reply)就通过binder传递到BnAudioPolicyService中了，这样就调用IAudioPolicyService.cpp的
BnAudioPolicyService::onTransact函数来处理该请求(但由于继承关系最终是派发到Bn的派生类AudioPolicyService::onTransact来处理，不过我们后面也会发现派生类又调回Bn类
的onTransact去处理，很有意思啊)，我们看看BnAudioPolicyService是如何获得remote()->transact(SET_STREAM_VOLUME, data, &reply)的请求的，这样要从
AudioPolicyService是如何将自己的服务添加到servicemanager中的说起，在frameworks/av/media/mediaserver/main_mediaserver.cpp中：
- 34 int main(int argc, char** argv)
- 35 {
- 36 sp<ProcessState> proc(ProcessState::self());
- 37 sp<IServiceManager> sm = defaultServiceManager();
- 38 ALOGI("ServiceManager: %p", sm.get());
- 39 AudioFlinger::instantiate();
- 40 MediaPlayerService::instantiate();
- 41 CameraService::instantiate();
- 42 AudioPolicyService::instantiate();
- 43 ProcessState::self()->startThreadPool();
- 44 IPCThreadState::self()->joinThreadPool();
- 45 }
然后看:
frameworks/native/libs/binder/ProcessState.cpp：
- 74 sp<ProcessState> ProcessState::self()
- 75 {
- 76 Mutex::Autolock _l(gProcessMutex);
- 77 if (gProcess != NULL) {
- 78 return gProcess;
- 79 }
- 80 gProcess = new ProcessState;
- 81 return gProcess;
- 82 }
- 335 ProcessState::ProcessState()
- 336 : mDriverFD(open_driver())
- 337 , mVMStart(MAP_FAILED)
- 338 , mManagesContexts(false)
- 339 , mBinderContextCheckFunc(NULL)
- 340 , mBinderContextUserData(NULL)
- 341 , mThreadPoolStarted(false)
- 342 , mThreadPoolSeq(1)
- 343 {
- 344 if (mDriverFD >= 0) {
- 345 // XXX Ideally, there should be a specific define for whether we
- 346 // have mmap (or whether we could possibly have the kernel module
- 347 // availabla).
- 348 #if !defined(HAVE_WIN32_IPC)
- 349 // mmap the binder, providing a chunk of virtual address space to receive transactions.
- 350 mVMStart = mmap(0, BINDER_VM_SIZE, PROT_READ, MAP_PRIVATE | MAP_NORESERVE, mDriverFD, 0);
- .................................
- }
回到main_mediaserver.cpp，37行defaultServiceManager()，在frameworks/native/libs/binder/IServiceManager.cpp中：
- 34 sp<IServiceManager> defaultServiceManager()
- 35 {
- 36 if (gDefaultServiceManager != NULL) return gDefaultServiceManager;
- 37
- 38 {
- 39 AutoMutex _l(gDefaultServiceManagerLock);
- 40 if (gDefaultServiceManager == NULL) {
- 41 gDefaultServiceManager = interface_cast<IServiceManager>(
- 42 ProcessState::self()->getContextObject(NULL));
- 43 }
- 44 }
- 45
- 46 return gDefaultServiceManager;
- 47 }
参数，表示和ServiceManager通讯：
- 89 sp<IBinder> ProcessState::getContextObject(const sp<IBinder>& caller)
- 90 {
- 91 return getStrongProxyForHandle(0);
- 92 }
interface_cast<IServiceManager>(new BpBinder(0)),interface_cast在前面已经分析过，所以最后变成new BpServiceManager(new BpBinder(0))。
接着进入main_mediaserver.cpp42行AudioPolicyService::instantiate(),先看看frameworks/av/services/audioflinger/AudioPolicyService.h中的继承关系：
- 37 class AudioPolicyService :
- 38 public BinderService<AudioPolicyService>,
- 39 public BnAudioPolicyService,
- 40 // public AudioPolicyClientInterface,
- 41 public IBinder::DeathRecipient
- 33 template<typename SERVICE>
- 34 class BinderService
- 35 {
- 36 public:
- 37 static status_t publish(bool allowIsolated = false) {
- 38 sp<IServiceManager> sm(defaultServiceManager());
- 39 return sm->addService(String16(SERVICE::getServiceName()), new SERVICE(), allowIsolated);
- 40 }
- 41
- 42 static void publishAndJoinThreadPool(bool allowIsolated = false) {
- 43 sp<IServiceManager> sm(defaultServiceManager());
- 44 sm->addService(String16(SERVICE::getServiceName()), new SERVICE(), allowIsolated);
- 45 ProcessState::self()->startThreadPool();
- 46 IPCThreadState::self()->joinThreadPool();
- 47 }
- 48
- 49 static void instantiate() { publish(); }
- 50
- 51 static status_t shutdown() {
- 52 return NO_ERROR;
- 53 }
- 54 };
BpServiceManager(new BpBinder(0))->addService(String16("media.audio_policy", new AudioPolicyService(), false)，进入BpServiceManger::addService的实现，这个
函数实现在frameworks/native/libs/binder/IServiceManager.cpp：
- 154 virtual status_t addService(const String16& name, const sp<IBinder>&service, bool allowIsolated)
- 156 {
- 157 Parcel data, reply;
- 158 data.writeInterfaceToken(IServiceManager::getInterfaceDescriptor());
- 159 data.writeString16(name);
- 160 data.writeStrongBinder(service);
- 161 data.writeInt32(allowIsolated ? 1 : 0);
- 162 status_t err = remote()->transact(ADD_SERVICE_TRANSACTION, data, &reply);
- 163 return err == NO_ERROR ? reply.readExceptionCode() : err;
- 164 }
ProcessState::ProcessState打开的驱动，用这块共享内存和servicemanager打交道,在底层的内核空间binder驱动会根据传进来的mHandle值判断目标服务地址，这里的
mHandle为0，所以调整servermanager的buffer指向本地内存共享空间，接着往下看main_mediaserver.cpp的43行ProcessState::self()-
>startThreadPool()，
在frameworks/native/libs/binder/ProcessState.cpp中：
- 136 void ProcessState::startThreadPool()
- 137 {
- 138 AutoMutex _l(mLock);
- 139 if (!mThreadPoolStarted) {
- 140 mThreadPoolStarted = true;
- 141 spawnPooledThread(true);
- 142 }
- 143 }
- 286 void ProcessState::spawnPooledThread(bool isMain)
- 287 {
- 288 if (mThreadPoolStarted) {
- 289 int32_t s = android_atomic_add(1, &mThreadPoolSeq);
- 290 char buf[16];
- 291 snprintf(buf, sizeof(buf), "Binder_%X", s);
- 292 ALOGV("Spawning new pooled thread, name=%s\n", buf);
- 293 sp<Thread> t = new PoolThread(isMain);
- 294 t->run(buf);
- 295 }
- 296 }
- 56 class PoolThread : public Thread
- 57 {
- 58 public:
- 59 PoolThread(bool isMain)
- 60 : mIsMain(isMain)
- 61 {
- 62 }
- 63
- 64 protected:
- 65 virtual bool threadLoop()
- 66 {
- 67 IPCThreadState::self()->joinThreadPool(mIsMain);
- 68 return false;
- 69 }
- 70
- 71 const bool mIsMain;
- 72 };
进入IPCThreadState.cpp中，result = talkWithDriver()等待client请求，最终会调用 executeCommand(cmd)函数来处理请求，而在executeCommand函数
中，最终会调用BBinder::transact来真正处理Client的请求，接下来再看一下BBinder::transact的实现，frameworks/native/libs/binder/Binder.cpp中：
- 97 status_t BBinder::transact(
- 98 uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
- 99 {
- 100 data.setDataPosition(0);
- 101
- 102 status_t err = NO_ERROR;
- 103 switch (code) {
- 104 case PING_TRANSACTION:
- 105 reply->writeInt32(pingBinder());
- 106 break;
- 107 default:
- 108 err = onTransact(code, data, reply, flags);
- 109 break;
- 110 }
- 111
- 112 if (reply != NULL) {
- 113 reply->setDataPosition(0);
- 114 }
- 115
- 116 return err;
- 117 }
这样由于虚函数onTransact的继承关系，最终调用了AudioPolicyService的onTransact方法，AudioPolicyService.cpp中：
- 610 status_t AudioPolicyService::onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
- 612 {
- 613 return BnAudioPolicyService::onTransact(code, data, reply, flags);
- 614 }
到这里BpAudioPolicyService和BnAudioPolicyService的binder通讯关系就完成了，回到前面IAudioPolicyService.cpp中的242行
remote()->transact(SET_STREAM_VOLUME, data, &reply);这里传进来的是SET_STREAM_VOLUME，所以调用BnAudioPolicyService::onTransact：
- 512 case SET_STREAM_VOLUME:{
- 513 CHECK_INTERFACE(IAudioPolicyService, data, reply);
- 514 audio_stream_type_t stream =
- 515 static_cast <audio_stream_type_t>(data.readInt32());
- 516 int index = data.readInt32();
- 517 audio_devices_t device = static_cast <audio_devices_t>(data.readInt32());
- 518 reply->writeInt32(static_cast <uint32_t>(setStreamVolumeIndex(stream,
- 519 index,
- 520 device)));
- 521 return NO_ERROR;
- 522 } break;
- 380 status_t AudioPolicyService::setStreamVolumeIndex(audio_stream_type_t stream,
- 381 int index,
- 382 audio_devices_t device)
- 383 {
- 384 if (mpAudioPolicy == NULL) {
- 385 return NO_INIT;
- 386 }
- 387 if (!settingsAllowed()) {
- 388 return PERMISSION_DENIED;
- 389 }
- 390 if (uint32_t(stream) >= AUDIO_STREAM_CNT) {
- 391 return BAD_VALUE;
- 392 }
- 393
- 394 if (mpAudioPolicy->set_stream_volume_index_for_device) {
- 395 return mpAudioPolicy->set_stream_volume_index_for_device(mpAudioPolicy,
- 396 stream,
- 397 index,
- 398 device);
- 399 } else {
- 400 return mpAudioPolicy->set_stream_volume_index(mpAudioPolicy, stream, index);
- 401 }
- 402 }
- 58 AudioPolicyService::AudioPolicyService()
- 59 : BnAudioPolicyService() , mpAudioPolicyDev(NULL) , mpAudioPolicy(NULL)
- 60 {
- 61 char value[PROPERTY_VALUE_MAX];
- 62 const struct hw_module_t *module;
- 63 int forced_val;
- 64 int rc;
- 65
- 66 Mutex::Autolock _l(mLock);
- 67
- 68 // start tone playback thread
- 69 mTonePlaybackThread = new AudioCommandThread(String8(""));
- 70 // start audio commands thread
- 71 mAudioCommandThread = new AudioCommandThread(String8("ApmCommand"));
- 72
- 73 /* instantiate the audio policy manager */
- 74 rc = hw_get_module(AUDIO_POLICY_HARDWARE_MODULE_ID, &module);
- 75 if(rc)
- 76 return;
- 77
- 78 rc = audio_policy_dev_open(module, &mpAudioPolicyDev);
- 79 ALOGE_IF(rc, "couldn't open audio policy device (%s)", strerror(-rc));
- 80 if (rc)
- 81 return;
- 82
- 83 rc = mpAudioPolicyDev->create_audio_policy(mpAudioPolicyDev, &aps_ops, this,
- 84 &mpAudioPolicy);
- 85 ALOGE_IF(rc, "couldn't create audio policy (%s)", strerror(-rc));
- 86 if (rc)
- 87 return;
- 88
- 89 rc = mpAudioPolicy->init_check(mpAudioPolicy);
- 90 ALOGE_IF(rc, "couldn't init_check the audio policy (%s)", strerror(-rc));
- 91 if (rc)
- 92 return;
- .......................
- }
#define AUDIO_POLICY_HARDWARE_MODULE_ID "audio_policy"
根据hw_get_module的判断关系，看hardware/libhardware_legacy/audio/Android.mk可知，最终调用的是audio_policy.default.so，通过hw_get_module函数的
load(class_id, path, module)打开audio_policy.default.so并返回句柄，接着78行audio_policy_dev_open，在libhardware/include/hardware/audio_policy.h
- 424 static inline int audio_policy_dev_open(const hw_module_t* module,
- 425 struct audio_policy_device** device)
- 426 {
- 427 return module->methods->open(module, AUDIO_POLICY_INTERFACE,
- 428 (hw_device_t**)device);
- 429 }
- 406 static int legacy_ap_dev_open(const hw_module_t* module, const char* name, hw_device_t** device)
- 408 {
- 409 struct legacy_ap_device *dev;
- 411 if (strcmp(name, AUDIO_POLICY_INTERFACE) != 0)
- 412 return -EINVAL;
- 414 dev = (struct legacy_ap_device *)calloc(1, sizeof(*dev));
- 415 if (!dev)
- 416 return -ENOMEM;
- 418 dev->device.common.tag = HARDWARE_DEVICE_TAG;
- 419 dev->device.common.version = 0;
- 420 dev->device.common.module = const_cast<hw_module_t*>(module);
- 421 dev->device.common.close = legacy_ap_dev_close;
- 422 dev->device.create_audio_policy = create_legacy_ap;
- 423 dev->device.destroy_audio_policy = destroy_legacy_ap;
- 425 *device = &dev->device.common;
- 427 return 0;
- 428 }
- 40 struct legacy_ap_device {
- 41 struct audio_policy_device device;
- 42 };
- 410 struct audio_policy_device {
- 411 struct hw_device_t common;
- 412
- 413 int (*create_audio_policy)(const struct audio_policy_device *device,
- 414 struct audio_policy_service_ops *aps_ops,
- 415 void *service,
- 416 struct audio_policy **ap);
- 417
- 418 int (*destroy_audio_policy)(const struct audio_policy_device *device,
- 419 struct audio_policy *ap);
- 420 };
audio_policy_device结构体的地址。所以接着AudioPolicyService.cpp的83行调用的是audio_policy_device的create_audio_policy，它指向create_legacy_ap函数：
- 311 static int create_legacy_ap(const struct audio_policy_device *device,
- 312 struct audio_policy_service_ops *aps_ops,
- 313 void *service,
- 314 struct audio_policy **ap)
- 315 {
- 316 struct legacy_audio_policy *lap;
- 317 int ret;
- 318
- 319 if (!service || !aps_ops)
- 320 return -EINVAL;
- 321
- 322 lap = (struct legacy_audio_policy *)calloc(1, sizeof(*lap));
- 323 if (!lap)
- 324 return -ENOMEM;
- 325
- 326 lap->policy.set_device_connection_state = ap_set_device_connection_state;
- 327 lap->policy.get_device_connection_state = ap_get_device_connection_state;
- 328 lap->policy.set_phone_state = ap_set_phone_state;
- 329 lap->policy.set_ringer_mode = ap_set_ringer_mode;
- 330 lap->policy.set_force_use = ap_set_force_use;
- 331 lap->policy.get_force_use = ap_get_force_use;
- 332 lap->policy.set_can_mute_enforced_audible = ap_set_can_mute_enforced_audible;
- 334 lap->policy.init_check = ap_init_check;
- 335 lap->policy.get_output = ap_get_output;
- 336 lap->policy.start_output = ap_start_output;
- 337 lap->policy.stop_output = ap_stop_output;
- 338 lap->policy.release_output = ap_release_output;
- 339 lap->policy.get_input = ap_get_input;
- 340 lap->policy.start_input = ap_start_input;
- 341 lap->policy.stop_input = ap_stop_input;
- 342 lap->policy.release_input = ap_release_input;
- 343 lap->policy.init_stream_volume = ap_init_stream_volume;
- 344 lap->policy.set_stream_volume_index = ap_set_stream_volume_index;
- 345 lap->policy.get_stream_volume_index = ap_get_stream_volume_index;
- 346 lap->policy.set_stream_volume_index_for_device = ap_set_stream_volume_index_for_device;
- 347 lap->policy.get_stream_volume_index_for_device = ap_get_stream_volume_index_for_device;
- 348 lap->policy.get_strategy_for_stream = ap_get_strategy_for_stream;
- 349 lap->policy.get_devices_for_stream = ap_get_devices_for_stream;
- 350 lap->policy.get_output_for_effect = ap_get_output_for_effect;
- 351 lap->policy.register_effect = ap_register_effect;
- 352 lap->policy.unregister_effect = ap_unregister_effect;
- 353 lap->policy.set_effect_enabled = ap_set_effect_enabled;
- 354 lap->policy.is_stream_active = ap_is_stream_active;
- 355 lap->policy.dump = ap_dump;
- 356
- 357 lap->service = service;
- 358 lap->aps_ops = aps_ops;
- 359 lap->service_client =
- 360 new AudioPolicyCompatClient(aps_ops, service);
- 361 if (!lap->service_client) {
- 362 ret = -ENOMEM;
- 363 goto err_new_compat_client;
- 364 }
- 365
- 366 lap->apm = createAudioPolicyManager(lap->service_client);
- 367 if (!lap->apm) {
- 368 ret = -ENOMEM;
- 369 goto err_create_apm;
- 370 }
- 371
- 372 *ap = &lap->policy;
- 373 return 0;
- 374
- 375 err_create_apm:
- 376 delete lap->service_client;
- 377 err_new_compat_client:
- 378 free(lap);
- 379 *ap = NULL;
- 380 return ret;
- 381 }
- 232 static int ap_set_stream_volume_index_for_device(struct audio_policy *pol,
- 233 audio_stream_type_t stream,
- 234 int index,
- 235 audio_devices_t device)
- 236 {
- 237 struct legacy_audio_policy *lap = to_lap(pol);
- 238 return lap->apm->setStreamVolumeIndex((AudioSystem::stream_type)stream,
- 239 index,
- 240 device);
- 241 }
- 44 struct legacy_audio_policy {
- 45 struct audio_policy policy;//即为mpAudioPolicy
- 46
- 47 void *service;
- 48 struct audio_policy_service_ops *aps_ops;
- 49 AudioPolicyCompatClient *service_client;
- 50 AudioPolicyInterface *apm;
- 51 };
- 24 extern "C" AudioPolicyInterface* createAudioPolicyManager(AudioPolicyClientInterface *clientInterface)
- 25 {
- 26 return new AudioPolicyManagerDefault(clientInterface);
- 27 }
- 25 class AudioPolicyManagerDefault: public AudioPolicyManagerBase
- 26 {
- 28 public:
- 29 AudioPolicyManagerDefault(AudioPolicyClientInterface *clientInterface)
- 30 : AudioPolicyManagerBase(clientInterface) {}
- 31
- 32 virtual ~AudioPolicyManagerDefault() {}
- 33
- 34 };
在AudioPolicyManagerBase.cpp中：
953 status_t AudioPolicyManagerBase::setStreamVolumeIndex(AudioSystem::stream_type stream, int index, audio_devices_t device)
- 956 {
- 958 if ((index < mStreams[stream].mIndexMin) || (index > mStreams[stream].mIndexMax)) {
- 959 return BAD_VALUE;
- 960 }
- 961 if (!audio_is_output_device(device)) {
- 962 return BAD_VALUE;
- 963 }
- 965 // Force max volume if stream cannot be muted
- 966 if (!mStreams[stream].mCanBeMuted) index = mStreams[stream].mIndexMax;
- 971 // if device is AUDIO_DEVICE_OUT_DEFAULT set default value and
- 972 // clear all device specific values
- 973 if (device == AUDIO_DEVICE_OUT_DEFAULT) {
- 974 mStreams[stream].mIndexCur.clear();
- 975 }
- 976 mStreams[stream].mIndexCur.add(device, index);
- 978 // compute and apply stream volume on all outputs according to connected device
- 979 status_t status = NO_ERROR;
- 980 for (size_t i = 0; i < mOutputs.size(); i++) {
- 981 audio_devices_t curDevice =
- 982 getDeviceForVolume((audio_devices_t)mOutputs.valueAt(i)->device());
- 983 if (device == curDevice) {
- 984 status_t volStatus = checkAndSetVolume(stream, index, mOutputs.keyAt(i), curDevice);
- 985 if (volStatus != NO_ERROR) {
- 986 status = volStatus;
- 987 }
- 988 }
- 989 }
- 990 return status;
- 991 }
- 2683 status_t AudioPolicyManagerBase::checkAndSetVolume(int stream,
- 2684 int index,
- 2685 audio_io_handle_t output,
- 2686 audio_devices_t device,
- 2687 int delayMs,
- 2688 bool force)
- 2689 {
- ....................
- 2722 if (stream == AudioSystem::BLUETOOTH_SCO) {
- 2723 mpClientInterface->setStreamVolume(AudioSystem::VOICE_CALL, volume, output, delayMs);
- 2724 }
- 2725 }
- 2726
- 2727 mpClientInterface->setStreamVolume((AudioSystem::stream_type)stream, volume, output, delayMs);
- ...................
- 2747 }
- 120 status_t AudioPolicyCompatClient::setStreamVolume(
- 121 AudioSystem::stream_type stream,
- 122 float volume,
- 123 audio_io_handle_t output,
- 124 int delayMs)
- 125 {
- 126 return mServiceOps->set_stream_volume(mService, (audio_stream_type_t)stream,
- 127 volume, output, delayMs);
- 128 }
- 32 class AudioPolicyCompatClient : public AudioPolicyClientInterface {
- 33 public:
- 34 AudioPolicyCompatClient(struct audio_policy_service_ops *serviceOps,
- 35 void *service) :
- 36 mServiceOps(serviceOps) ,
- mService(service) {}
frameworks/av/services/audioflinger/AudioPolicyService.cpp中：
- 1538 struct audio_policy_service_ops aps_ops = {
- 1539 open_output : aps_open_output,
- 1540 open_duplicate_output : aps_open_dup_output,
- 1541 close_output : aps_close_output,
- 1542 suspend_output : aps_suspend_output,
- 1543 restore_output : aps_restore_output,
- 1544 open_input : aps_open_input,
- 1545 close_input : aps_close_input,
- 1546 set_stream_volume : aps_set_stream_volume,
- 1547 set_stream_output : aps_set_stream_output,
- 1548 set_parameters : aps_set_parameters,
- 1549 get_parameters : aps_get_parameters,
- 1550 start_tone : aps_start_tone,
- 1551 stop_tone : aps_stop_tone,
- 1552 set_voice_volume : aps_set_voice_volume,
- 1553 move_effects : aps_move_effects,
- 1554 load_hw_module : aps_load_hw_module,
- 1555 open_output_on_module : aps_open_output_on_module,
- 1556 open_input_on_module : aps_open_input_on_module,
- 1557 };
- 1503 static int aps_set_stream_volume(void *service, audio_stream_type_t stream,
- 1504 float volume, audio_io_handle_t output,
- 1505 int delay_ms)
- 1506 {
- 1507 AudioPolicyService *audioPolicyService = (AudioPolicyService *)service;
- 1508
- 1509 return audioPolicyService->setStreamVolume(stream, volume, output,
- 1510 delay_ms);
- 1511 }
的setStreamVolume，噢，My Lady GaGa!
看看setStreamVolume的实现：
- 1006 int AudioPolicyService::setStreamVolume(audio_stream_type_t stream,
- 1007 float volume,
- 1008 audio_io_handle_t output,
- 1009 int delayMs)
- 1010 {
- 1011 return (int)mAudioCommandThread->volumeCommand(stream, volume,
- 1012 output, delayMs);
- 1013 }
- 800 status_t AudioPolicyService::AudioCommandThread::volumeCommand(audio_stream_type_t stream,
- 801 float volume,
- 802 audio_io_handle_t output,
- 803 int delayMs)
- 804 {
- 805 status_t status = NO_ERROR;
- 806
- 807 AudioCommand *command = new AudioCommand();
- 808 command->mCommand = SET_VOLUME;
- 809 VolumeData *data = new VolumeData();
- 810 data->mStream = stream;
- 811 data->mVolume = volume;
- 812 data->mIO = output;
- 813 command->mParam = data;
- 814 if (delayMs == 0) {
- 815 command->mWaitStatus = true;
- 816 } else {
- 817 command->mWaitStatus = false;
- 818 }
- 819 Mutex::Autolock _l(mLock);
- 820 insertCommand_l(command, delayMs);
- 821 ALOGV("AudioCommandThread() adding set volume stream %d, volume %f, output %d",
- 822 stream, volume, output);
- 823 mWaitWorkCV.signal();
- 824 if (command->mWaitStatus) {
- 825 command->mCond.wait(mLock);
- 826 status = command->mStatus;
- 827 mWaitWorkCV.signal();
- 828 }
- 829 return status;
- 830 }
- bool AudioPolicyService::AudioCommandThread::threadLoop()
- {
- 681 case SET_VOLUME: {
- 682 VolumeData *data = (VolumeData *)command->mParam;
- 683 ALOGV("AudioCommandThread() processing set volume stream %d, \
- 684 volume %f, output %d", data->mStream, data->mVolume, data->mIO);
- 685 command->mStatus = AudioSystem::setStreamVolume(data->mStream,
- 686 data->mVolume,
- 687 data->mIO);
- 688 if (command->mWaitStatus) {
- 689 command->mCond.signal();
- 690 mWaitWorkCV.wait(mLock);
- 691 }
- 692 delete data;
- 693 }break;
- }
- 123 status_t AudioSystem::setStreamVolume(audio_stream_type_t stream, float value,
- 124 audio_io_handle_t output)
- 125 {
- 126 if (uint32_t(stream) >= AUDIO_STREAM_CNT) return BAD_VALUE;
- 127 const sp<IAudioFlinger>& af = AudioSystem::get_audio_flinger();
- 128 if (af == 0) return PERMISSION_DENIED;
- 129 af->setStreamVolume(stream, value, output);
- 130 return NO_ERROR;
- 131 }
- 49 const sp<IAudioFlinger>& AudioSystem::get_audio_flinger()
- 50 {
- 51 Mutex::Autolock _l(gLock);
- 52 if (gAudioFlinger == 0) {
- 53 sp<IServiceManager> sm = defaultServiceManager();
- 54 sp<IBinder> binder;
- 55 do {
- 56 binder = sm->getService(String16("media.audio_flinger"));
- 57 if (binder != 0)
- 58 break;
- 59 ALOGW("AudioFlinger not published, waiting...");
- 60 usleep(500000); // 0.5 s
- 61 } while (true);
- 62 if (gAudioFlingerClient == NULL) {
- 63 gAudioFlingerClient = new AudioFlingerClient();
- 64 } else {
- 65 if (gAudioErrorCallback) {
- 66 gAudioErrorCallback(NO_ERROR);
- 67 }
- 68 }
- 69 binder->linkToDeath(gAudioFlingerClient);
- 70 gAudioFlinger = interface_cast<IAudioFlinger>(binder);
- 71 gAudioFlinger->registerClient(gAudioFlingerClient);
- 72 }
- 73 ALOGE_IF(gAudioFlinger==0, "no AudioFlinger!?");
- 74
- 75 return gAudioFlinger;
- 76 }
- 255 virtual status_t setStreamVolume(audio_stream_type_t stream, float value,
- 256 audio_io_handle_t output)
- 257 {
- 258 Parcel data, reply;
- 259 data.writeInterfaceToken(IAudioFlinger::getInterfaceDescriptor());
- 260 data.writeInt32((int32_t) stream);
- 261 data.writeFloat(value);
- 262 data.writeInt32((int32_t) output);
- 263 remote()->transact(SET_STREAM_VOLUME, data, &reply);
- 264 return reply.readInt32();
- 265 }
BnAudioFlinger::onTransact函数：
- 780 case SET_STREAM_VOLUME: {
- 781 CHECK_INTERFACE(IAudioFlinger, data, reply);
- 782 int stream = data.readInt32();
- 783 float volume = data.readFloat();
- 784 audio_io_handle_t output = (audio_io_handle_t) data.readInt32();
- 785 reply->writeInt32( setStreamVolume((audio_stream_type_t) stream, volume, output) );
- 786 return NO_ERROR;
- 761 status_t AudioFlinger::setStreamVolume(audio_stream_type_t stream, float value,
- 762 audio_io_handle_t output)
- 763 {
- 764 // check calling permissions
- 765 if (!settingsAllowed()) {
- 766 return PERMISSION_DENIED;
- 767 }
- 769 if (uint32_t(stream) >= AUDIO_STREAM_CNT) {//定义在system/core/include/system/audio.h
- 771 return BAD_VALUE;
- 772 }
- 774 AutoMutex lock(mLock);
- 775 PlaybackThread *thread = NULL;
- 776 if (output) {
- 777 thread = checkPlaybackThread_l(output);
- 778 if (thread == NULL) {
- 779 return BAD_VALUE;
- 780 }
- 781 }
- 783 mStreamTypes[stream].volume = value;
- 785 if (thread == NULL) {
- 786 for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
- 787 mPlaybackThreads.valueAt(i)->setStreamVolume(stream, value);
- 788 }
- 789 } else {
- 790 thread->setStreamVolume(stream, value);
- 791 }
- 793 return NO_ERROR;
- 794 }
这篇关于android audio音量控制流程的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
