1. 안드로이드의 모든것 분석과 포팅 정리
Android Audio System
(AudioPolicyService)
박철희
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2. 1.Audiopolicyservice 위치 및 역활 안드로이드의 모든것 분석과 포팅 정리
Application 역할:
Framework
1.현재 입출력 디바이스의
연결 상태 파악 및
routing을 위한 조건 check
Native
Framework 2.중간 다리 역활
HAL
Kernel
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3. 2.AudiopolicyService class 구조 안드로이드의 모든것 분석과 포팅 정리
IInterface
IaudioPolicyService
BnAudioPolicyService AudioPolicyClientInterface IBinder::DeathRecipient
AudiopolicyService
AudioPolicyInterface
AudioPolicyManagerBase
AudiopolicyManager
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4. 3.AudioPolicyService의 초기화 안드로이드의 모든것 분석과 포팅 정리
Main_mediaserver.cpp
int main(int argc, char** argv)
{
AudioFlinger::instantiate();
MediaPlayerService::instantiate();
CameraService::instantiate();
AudioPolicyService::instantiate();
ProcessState::self()->startThreadPool();
IPCThreadState::self()->joinThreadPool();
}
bool AudioPolicyService::
AudioCommandThread::threadLoop()
AudioPolicyService.cpp {
void AudioPolicyService::instantiate() { case START_TONE,
defaultServiceManager()->addService( case STOP_TONE:
String16("media.audio_policy"), new AudioPolicyService());  mTonePlaybackThread 처리
} case SET_VOLUME:
case SET_PARAMETERS:
case SET_VOICE_VOLUME:
AudioPolicyService::AudioPolicyService() case SET_FM_VOLUME:
: BnAudioPolicyService() , mpPolicyManager(NULL)  mAudioCommandThread 처리
{
// start tone playback thread(START_TONE,STOP_TONE) }
mTonePlaybackThread = new AudioCommandThread(String8(""));
// start audio commands thread(SET_VOLUME, SET_PARAMETERS, SET_VOICE_VOLUME, SET_FM_VOLUME)
mAudioCommandThread = new AudioCommandThread(String8("ApmCommandThread"));
mpPolicyManager = createAudioPolicyManager(this);
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5. 3.AudioPolicyService의 초기화 안드로이드의 모든것 분석과 포팅 정리
Hardware/msm7k/libaudio-msm7x30/audiopolicymanager.cpp
extern "C" AudioPolicyInterface* createAudioPolicyManager(AudioPolicyClientInterface *clientInterface)
{
return new AudioPolicyManager(clientInterface);
}
Android.mk(AudioFlinger) Hardware/msm7k/libaudio-msm7x30/Android.mk
LOCAL_SRC_FILES := AudioPolicyManager.cpp
libAudio libaudioPolicy LOCAL_SHARED_LIBRARIES := libcutils
LOCAL_SHARED_LIBRARIES += libutils
LOCAL_SHARED_LIBRARIES += libmedia
LOCAL_MODULE := libaudiopolicy
class AudioPolicyManager: public AudioPolicyManagerBase
{ AudioPolicyInterface
public:
AudioPolicyManager(AudioPolicyClientInterface *clientInterface)
: AudioPolicyManagerBase(clientInterface) {
mLPADecodeOutput = -1; AudioPolicyManagerBase
mLPAMuted = false; AudioPolicyService
mLPAStreamType = AudioSystem::DEFAULT;
}
AudiopolicyManager
…
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6. 3.AudioPolicyService의 초기화 안드로이드의 모든것 분석과 포팅 정리
Ex)Audiopolicyservice의 getoutput method를 호출할 경우
audiopolicymanager.cpp에는 이 함수가 없다. 대신 상속받은 AudioPolicyManagerBase.cpp에 존재 함.
AudioPolicyService.cpp
audio_io_handle_t AudioPolicyService::getOutput
{
return mpPolicyManager->getOutput(stream, samplingRate, format, channels, flags);
}
AudioPolicyManagerBase.cpp
audio_io_handle_t AudioPolicyManagerBase::getOutput(…)
{
…
mpClientInterface->openOutput(&outputDesc->mDevice,
&outputDesc->mSamplingRate,
&outputDesc->mFormat,
&outputDesc->mChannels,
AudioPolicyService
&outputDesc->mLatency,
outputDesc->mFlags);
}
audio_io_handle_t AudioPolicyService::openOutput
{
af->openOutput(pDevices ,…);
}
Audioflinger
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7. 3.AudioPolicyService의 초기화 안드로이드의 모든것 분석과 포팅 정리
int AudioFlinger::openOutput
{
AudioStreamOut *output = mAudioHardware->openOutputStream(*pDevices,
(int *)&format,
&channels,
&samplingRate,
&status);
// notify client processes of the new output creation
thread->audioConfigChanged_l(AudioSystem::OUTPUT_OPENED);
}
void AudioFlinger::PlaybackThread::audioConfigChanged_l
{
mAudioFlinger->audioConfigChanged_l(event, param, NULL);
}
void AudioFlinger::audioConfigChanged_l
{
mNotificationClients.valueAt(i)->client()->ioConfigChanged(event, ioHandle, param2);
}
AudioSystem::AudioFlingerClient
아래와 같은 함수들에서 현재 output stream의
정보를 구할 때 gOutputs 가 사용된다.
void AudioSystem::AudioFlingerClient::ioConfigChanged
getOutputSamplingRate
{
getOutputFrameCount
gOutputs.add(ioHandle, outputDesc);
getOutputLatency
}
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8. 4.AudioPolicyManager의 초기화 안드로이드의 모든것 분석과 포팅 정리
class AudioPolicyManager: public AudioPolicyManagerBase
{
public:
AudioPolicyManager(AudioPolicyClientInterface *clientInterface)
: AudioPolicyManagerBase(clientInterface) {
mLPADecodeOutput = -1;
mLPAMuted = false;
mLPAStreamType = AudioSystem::DEFAULT;
}
AudioPolicyService
AudioPolicyManagerBase::AudioPolicyManagerBase(AudioPolicyClientInterface *clientInterface)
{
//audiopolicyservice를 변수에 저장한다.
mpClientInterface = clientInterface;
uint32_t defaultDevice = (uint32_t) AudioSystem::DEVICE_OUT_SPEAKER;
mHardwareOutput = mpClientInterface->openOutput(&outputDesc->mDevice,
&outputDesc->mSamplingRate,
&outputDesc->mFormat,
&outputDesc->mChannels,
&outputDesc->mLatency,
outputDesc->mFlags);
mHardwareOutput 는 playbackthread의 id
setOutputDevice(mHardwareOutput, defaultDevice, true);
}
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9. 4.AudioPolicyManager의 초기화 안드로이드의 모든것 분석과 포팅 정리
void AudioPolicyManagerBase::setOutputDevice
{
…
// do the routing
//mHardwareOutput:playbackthread의 id
//device: AudioSystem::DEVICE_OUT_SPEAKER
AudioParameter param = AudioParameter();
param.addInt(String8(AudioParameter::keyRouting), (int)device);
mpClientInterface->setParameters(mHardwareOutput, param.toString(), delayMs);
}
void AudioPolicyService::setParameters
{
mAudioCommandThread->parametersCommand((int)ioHandle, keyValuePairs, delayMs);
// mAudioCommandThread 는 AudioPolicyService 생성자에서 생성된 thread
}
status_t AudioPolicyService::AudioCommandThread::parametersCommand
{
insertCommand_l(command, delayMs);
 SET_PARAMETERS command를 mAudioCommands에 insert한다.
}
Threadloop으로 돌고 있는 AudioCommandThread 에서 처리한다.
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10. 4.AudioPolicyManager의 초기화 안드로이드의 모든것 분석과 포팅 정리
bool AudioPolicyService::AudioCommandThread::threadLoop()
{
…
case SET_PARAMETERS:
command->mStatus = AudioSystem::setParameters(data->mIO, data->mKeyValuePairs);
}
AudioSystem.cpp
status_t AudioSystem::setParameters
{
return af->setParameters(ioHandle, keyValuePairs);
}
AudioFlinger.cpp
status_t AudioFlinger::setParameters
{
//현재 설정된 palybackthread의 parent class인 threadbase의 setParameters를 호출함.
result = thread->setParameters(keyValuePairs);
}
status_t AudioFlinger::ThreadBase::setParameters
{
mNewParameters.add(keyValuePairs);
}
bool AudioFlinger::MixerThread::threadLoop()
{
checkForNewParameters_l()
}
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11. 4.AudioPolicyManager의 초기화 안드로이드의 모든것 분석과 포팅 정리
bool AudioFlinger::MixerThread::checkForNewParameters_l()
{
sendConfigEvent_l(AudioSystem::OUTPUT_CONFIG_CHANGED);
}
void AudioFlinger::ThreadBase::sendConfigEvent_l(int event, int param)
{
mConfigEvents.add(configEvent);
}
bool AudioFlinger::MixerThread::threadLoop()
{
processConfigEvents();
}
void AudioFlinger::ThreadBase::processConfigEvents()
{
audioConfigChanged_l(configEvent->mEvent, configEvent->mParam);
}
void AudioFlinger::audioConfigChanged_l
{
mNotificationClients.valueAt(i)->client()->ioConfigChanged(event, ioHandle, param2);
}
void AudioSystem::AudioFlingerClient::ioConfigChanged
{
case OUTPUT_CONFIG_CHANGED:
gOutputs.replaceValueFor(ioHandle, outputDesc);
}
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