Android audio切换设备通道流程

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Android audio切换设备通道流程
1.frameworks/base/media/java/android/media/AudioManager.java
public void setMode(int mode) {
IAudioService service = getService();
try {
service.setMode(mode, mICallBack, mApplicationContext.getOpPackageName());
} catch (RemoteException e) {
Log.e(TAG, "Dead object in setMode", e);
}
}

2.frameworks/base/services/core/java/com/android/server/audio/AudioService.java
<1>.public void setMode(int mode, IBinder cb, String callingPackage) {
newModeOwnerPid = setModeInt(mode, cb, Binder.getCallingPid(), callingPackage);
}
<2>.private int setModeInt(int mode, IBinder cb, int pid, String caller) {
status = AudioSystem.setPhoneState(mode);
}

3.frameworks/base/media/java/android/media/AudioSystem.java
public static native int setPhoneState(int state);

4.frameworks/base/core/jni/android_media_AudioSystem.cpp
<1>.static JNINativeMethod gMethods[] = {
{"setPhoneState", "(I)I", (void *)android_media_AudioSystem_setPhoneState},
};
<2>.static jint android_media_AudioSystem_setPhoneState(JNIEnv *env, jobject thiz, jint state){
return (jint) check_AudioSystem_Command(AudioSystem::setPhoneState((audio_mode_t) state));
}

5.frameworks/av/media/libmedia/AudioSystem.cpp
status_t AudioSystem::setPhoneState(audio_mode_t state)
{
if (uint32_t(state) >= AUDIO_MODE_CNT) return BAD_VALUE;
const sp<IAudioPolicyService>& aps = AudioSystem::get_audio_policy_service();
if (aps == 0) return PERMISSION_DENIED;

return aps->setPhoneState(state);
}

6.frameworks/av/include/media/IAudioPolicyService.h
class IAudioPolicyService : public IInterface{
public:
DECLARE_META_INTERFACE(AudioPolicyService);
};

7.frameworks/native/include/binder/IInterface.h:
#include <media/IAudioPolicyServiceClient.h>

#define DECLARE_META_INTERFACE(INTERFACE) \
static const android::String16 descriptor; \
static android::sp<I##INTERFACE> asInterface( \
const android::sp<android::IBinder>& obj); \
virtual const android::String16& getInterfaceDescriptor() const; \
I##INTERFACE(); \
virtual ~I##INTERFACE();
8.frameworks/av/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp
#include "AudioPolicyService.h"
status_t AudioPolicyService::setPhoneState(audio_mode_t state){
AudioSystem::setMode(state);
mpAudioPolicy->set_phone_state(mpAudioPolicy, state);//给毁掉函数传state值
mPhoneState = state;
}
9.定义和使用
<1>.hardware/libhardware/include/hardware/audio_policy.h
//定义回调
void (*set_phone_state)(struct audio_policy *pol, audio_mode_t state);

<2>hardware/libhardware/modules/audio/audio_policy.c
static int create_legacy_ap(const struct audio_policy_device *device,
struct audio_policy_service_ops *aps_ops,
void *service,
struct audio_policy **ap)
{
lap->policy.set_phone_state = ap_set_phone_state;//回调
}

static void ap_set_phone_state(struct audio_policy *pol, audio_mode_t state)
{
struct legacy_audio_policy *lap = to_lap(pol);
// as this is the legacy API, don't change it to use audio_mode_t instead of int
lap->apm->setPhoneState((int) state);
}

10.定义和使用
<1>.hardware/qcom/audio/policy_hal/AudioPolicyManager.h
virtual void setPhoneState(audio_mode_t state);

<2>.hardware/libhardware_legacy/include/hardware_legacy/AudioPolicyManagerBase.h
enum routing_strategy {
STRATEGY_MEDIA,
STRATEGY_PHONE,
STRATEGY_SONIFICATION,
STRATEGY_SONIFICATION_RESPECTFUL,
STRATEGY_DTMF,
STRATEGY_ENFORCED_AUDIBLE,
NUM_STRATEGIES
};

<3>.hardware/qcom/audio/policy_hal/AudioPolicyManager.cpp
（1）void AudioPolicyManagerCustom::setPhoneState(audio_mode_t state){

setStrategyMute(STRATEGY_MEDIA, true, mOutputs.keyAt(i));
setStrategyMute(STRATEGY_MEDIA, false, mOutputs.keyAt(i), MUTE_TIME_MS, getDeviceForStrategy(STRATEGY_MEDIA, true /*fromCache*/));
setStrategyMute(STRATEGY_SONIFICATION, true, mOutputs.keyAt(i));
setStrategyMute(STRATEGY_SONIFICATION, false, mOutputs.keyAt(i), MUTE_TIME_MS,getDeviceForStrategy(STRATEGY_SONIFICATION, true /*fromCache*/));
}
（2）audio_devices_t AudioPolicyManagerBase::getDeviceForStrategy(routing_strategy strategy,bool fromCache)
{
case STRATEGY_SONIFICATION:

// If incall, just select the STRATEGY_PHONE device: The rest of the behavior is handled by
// handleIncallSonification().
if (isInCall()) {
device = getDeviceForStrategy(STRATEGY_PHONE, false /*fromCache*/);
break;
}
}

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