AudioFlinger(AF)是一个服务,具体的启动代码在av\media\mediaserver\Main_mediaserver.cpp中：
int main(int argc, char** argv)
{
signal(SIGPIPE, SIG_IGN);
char value[PROPERTY_VALUE_MAX];
bool doLog = (property_get("ro.test_harness", value, "") > ) && (atoi(value) == );
pid_t childPid;
// FIXME The advantage of making the process containing media.log service the parent process of
// the process that contains all the other real services, is that it allows us to collect more
// detailed information such as signal numbers, stop and continue, resource usage, etc.
// But it is also more complex. Consider replacing this by independent processes, and using
// binder on death notification instead.
if (doLog && (childPid = fork()) != ) {
// media.log service
//prctl(PR_SET_NAME, (unsigned long) "media.log", 0, 0, 0);
// unfortunately ps ignores PR_SET_NAME for the main thread, so use this ugly hack
strcpy(argv[], "media.log");
sp<ProcessState> proc(ProcessState::self());
MediaLogService::instantiate();
ProcessState::self()->startThreadPool();
......
sp<ProcessState> proc(ProcessState::self());
sp<IServiceManager> sm = defaultServiceManager();
ALOGI("ServiceManager: %p", sm.get());
AudioFlinger::instantiate();
MediaPlayerService::instantiate();
CameraService::instantiate();
AudioPolicyService::instantiate();
registerExtensions();
ProcessState::self()->startThreadPool();
IPCThreadState::self()->joinThreadPool();
}
}
追踪AudioFlinger::instantiate()函数的实现可到native\include\binder\BinderService.h中的
static status_t publish(bool allowIsolated = false) {
sp<IServiceManager> sm(defaultServiceManager());
return sm->addService(
String16(SERVICE::getServiceName()),
new SERVICE(), allowIsolated);
}
static void instantiate() { publish(); }
然后再往哪儿追踪代码就不知道了，没那个时间，不要在意细节，继续看AudioFlinger的构造函数：
AudioFlinger::AudioFlinger()
: BnAudioFlinger(),//初始化基类
mPrimaryHardwareDev(NULL),
mHardwareStatus(AUDIO_HW_IDLE),
mMasterVolume(1.0f),
mMasterMute(false),
mNextUniqueId(),
mMode(AUDIO_MODE_INVALID),
mBtNrecIsOff(false),
mIsLowRamDevice(true),
mIsDeviceTypeKnown(false),
mGlobalEffectEnableTime()
{
getpid_cached = getpid();
char value[PROPERTY_VALUE_MAX];
bool doLog = (property_get("ro.test_harness", value, "") > ) && (atoi(value) == );
if (doLog) {
mLogMemoryDealer = new MemoryDealer(kLogMemorySize, "LogWriters");
}
#ifdef TEE_SINK
(void) property_get("ro.debuggable", value, "");
int debuggable = atoi(value);
int teeEnabled = ;
if (debuggable) {
(void) property_get("af.tee", value, "");
teeEnabled = atoi(value);
}
if (teeEnabled & )
mTeeSinkInputEnabled = true;
if (teeEnabled & )
mTeeSinkOutputEnabled = true;
if (teeEnabled & )
mTeeSinkTrackEnabled = true;
#endif
}
设置硬件的各种属性状态。