转载 ADROID 2.1 架构解析 十 声音

转载 ADROID 2.1 架构解析 10 声音
10 声音
10.1 音频管理
文件： frameworks/base/media/java/android/media/AudioManager.java

10.1.1 音量控制

/**  @hide Default volume index values for audio streams */     public static final int[] DEFAULT_STREAM_VOLUME = new int[] {         4,  // STREAM_VOICE_CALL          7,  // STREAM_SYSTEM         5,  // STREAM_RING         11, // STREAM_MUSIC         6,  // STREAM_ALARM         5,  // STREAM_NOTIFICATION         7,  // STREAM_BLUETOOTH_SCO         7,  // STREAM_SYSTEM_ENFORCED         11, // STREAM_DTMF         11  // STREAM_TTS }; 

以上结构定义了默认音量。

public void adjustStreamVolume(int streamType, int direction, int flags) {         IAudioService service = getService();         try {             service.adjustStreamVolume(streamType, direction, flags);         } catch (RemoteException e) {             Log.e(TAG, "Dead object in adjustStreamVolume", e);         } } public void setStreamVolume(int streamType, int index, int flags) {         IAudioService service = getService();         try {             service.setStreamVolume(streamType, index, flags);         } catch (RemoteException e) {             Log.e(TAG, "Dead object in setStreamVolume", e);         }     } 

将音量控制参数转给音频服务去处理。

10.1.2 播放控制

@Deprecated public void setParameter(String key, String value) {         setParameters(key+"="+value);     }       /**      * Sets a variable number of parameter values to audio hardware.      *      * @param keyValuePairs list of parameters key value pairs in the form:      *    key1=value1;key2=value2;...      *      */     public void setParameters(String keyValuePairs) {         AudioSystem.setParameters(keyValuePairs); } 

cupcake 的播放控制采用的是 setrouting() 方式进行， eclaire 的播放控制改用 setParameter 方式，用参数设置的方式进行。

以上代码的功能是：将参数传给音频系统去进行处理。

10.2 音频服务
文件： frameworks/base/media/java/android/media/AudioService.java

10.2.1 音效

 private static final String SOUND_EFFECTS_PATH = "/media/audio/ui/";     private static final String[] SOUND_EFFECT_FILES = new String[] {         "Effect_Tick.ogg",         "KeypressStandard.ogg",         "KeypressSpacebar.ogg",         "KeypressDelete.ogg",         "KeypressReturn.ogg" }; public boolean loadSoundEffects() {         ... String filePath = Environment.getRootDirectory() + SOUND_EFFECTS_PATH + SOUND_EFFECT_FILES[SOUND_EFFECT_FILES_MAP[effect][0]];               ...         return true; } 

音效文件放在： /system/media/audio/ui/ 目录下。

10.2.2 音量

public void setStreamVolume(int streamType, int index, int flags) {         ensureValidStreamType(streamType);         index = rescaleIndex(index * 10, streamType, STREAM_VOLUME_ALIAS[streamType]);         setStreamVolumeInt(STREAM_VOLUME_ALIAS[streamType], index, false, true);           // UI, etc.         mVolumePanel.postVolumeChanged(streamType, flags);         // Broadcast Intent         sendVolumeUpdate(streamType); } private void setStreamVolumeInt(int streamType, int index, boolean force, boolean lastAudible) {         VolumeStreamState streamState = mStreamStates[streamType];         if (streamState.setIndex(index, lastAudible) || force) {             // Post message to set system volume (it in turn will post a message             // to persist). Do not change volume if stream is muted.             if (streamState.muteCount() == 0) {                  sendMsg(mAudioHandler, MSG_SET_SYSTEM_VOLUME, streamType, SENDMSG_NOOP, 0, 0,                         streamState, 0);             }         } } private class AudioHandler extends Handler { private void setStreamVolumeIndex(int stream, int index) {          AudioSystem.setStreamVolumeIndex(s tream, (index + 5)/10); }           private void setSystemVolume(VolumeStreamState streamState) {               // Adjust volume             setStreamVolumeIndex (streamState.mStreamType, streamState.mIndex); ...          } public void handleMessage(Message msg) {             int baseMsgWhat = getMsgBase(msg.what);               switch (baseMsgWhat) {                   case MSG_SET_SYSTEM_VOLUME:                     setSystemVolume((VolumeStreamState) msg.obj);                      break; ... 

音量设置通过消息发给消息处理，然后再转向音频系统进行处理：

AudioSystem.setStreamVolumeIndex

10.3 音频系统
文件： frameworks/base/media/java/android/media/AudioSystem.java

10.3.1 音频类型

/* The audio stream for phone calls */     public static final int STREAM_VOICE_CALL = 0;      /* The audio stream for system sounds */     public static final int STREAM_SYSTEM = 1;     /* The audio stream for the phone ring and message alerts */     public static final int STREAM_RING = 2;     /* The audio stream for music playback */     public static final int STREAM_MUSIC = 3;     /* The audio stream for alarms */     public static final int STREAM_ALARM = 4;     /* The audio stream for notifications */     public static final int STREAM_NOTIFICATION = 5;     /* @hide The audio stream for phone calls when connected on bluetooth */     public static final int STREAM_BLUETOOTH_SCO = 6;     /* @hide The audio stream for enforced system sounds in certain countries (e.g camera in Japan) */     public static final int STREAM_SYSTEM_ENFORCED = 7;     /* @hide The audio stream for DTMF tones */      public static final int STREAM_DTMF = 8;     /* @hide The audio stream for text to speech (TTS) */ public static final int STREAM_TTS = 9; 

10.3.2 输入输出设备

// output devices     public static final int DEVICE_OUT_EARPIECE = 0x1;     public static final int DEVICE_OUT_SPEAKER = 0x2;     public static final int DEVICE_OUT_WIRED_HEADSET = 0x4;     public static final int DEVICE_OUT_WIRED_HEADPHONE = 0x8;     public static final int DEVICE_OUT_BLUETOOTH_SCO = 0x10;      public static final int DEVICE_OUT_BLUETOOTH_SCO_HEADSET = 0x20;     public static final int DEVICE_OUT_BLUETOOTH_SCO_CARKIT = 0x40;     public static final int DEVICE_OUT_BLUETOOTH_A2DP = 0x80;     public static final int DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES = 0x100;     public static final int DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER = 0x200;     public static final int DEVICE_OUT_AUX_DIGITAL = 0x400;     public static final int DEVICE_OUT_DEFAULT = 0x8000;     // input devices     public static final int DEVICE_IN_COMMUNICATION = 0x10000;     public static final int DEVICE_IN_AMBIENT = 0x20000;     public static final int DEVICE_IN_BUILTIN_MIC1 = 0x40000;     public static final int DEVICE_IN_BUILTIN_MIC2 = 0x80000;     public static final int DEVICE_IN_MIC_ARRAY = 0x100000;     public static final int DEVICE_IN_BLUETOOTH_SCO_HEADSET = 0x200000;     public static final int DEVICE_IN_WIRED_HEADSET = 0x400000;     public static final int DEVICE_IN_AUX_DIGITAL = 0x800000; public static final int DEVICE_IN_DEFAULT = 0x80000000; 

10.3.3 转向底层处理

public static native int setParameters(String keyValuePairs); public static native int setStreamVolumeIndex(int stream, int index); 

对于参数设置和音量设置都转向 C/C++ 文件进行处理。

10.4 音频系统底层处理
文件： frameworks/base/media/libmedia/AudioSystem.cpp

10.4.1 音量设置

const sp<IAudioPolicyService>& AudioSystem::get_audio_policy_service() {     ...         sp<IServiceManager> sm = defaultServiceManager();               ...         binder = sm->getService(String16("media.audio_policy"));            ... } status_t AudioSystem::setStreamVolumeIndex(stream_type stream, int index) {     const sp<IAudioPolicyService>& aps = AudioSystem::get_audio_policy_service();     if (aps == 0) return PERMISSION_DENIED;      return aps->setStreamVolumeIndex(stream, index); } 

将参数传给音频策略进行处理。

10.4.1 参数设置

const sp<IAudioFlinger>& AudioSystem::get_audio_flinger() {     ...         sp<IServiceManager> sm = defaultServiceManager();        ..             binder = sm->getService(String16("media.audio_flinger"));         ... } status_t AudioSystem::setParameters(audio_io_handle_t ioHandle, const String8& keyValuePairs) {     const sp<IAudioFlinger>& af = AudioSystem::get_audio_flinger();     if (af == 0) return PERMISSION_DENIED;     return af->setParameters(ioHandle, keyValuePairs); } 

将参数传给音频投掷进行处理。

主参数：

const char *AudioParameter::keyRouting = "routing"; const char *AudioParameter::keySamplingRate = "sampling_rate"; const char *AudioParameter::keyFormat = "format"; const char *AudioParameter::keyChannels = "channels"; const char *AudioParameter::keyFrameCount = "frame_count"; 

10.5 音频策略
文件： frameworks/base/libs/audioflinger/AudioPolicyService.cpp

void AudioPolicyService::instantiate() {     defaultServiceManager()->addService(             String16("media.audio_policy"), new AudioPolicyService()); } 

注册名为 media.audio_policy 的服务。

AudioPolicyService::AudioPolicyService()     : BnAudioPolicyService() , mpPolicyManager(NULL) {     ...         mpPolicyManager = createAudioPolicyManager(this);     ... } 

调用音频策略管理器。

status_t AudioPolicyService::setStreamVolumeIndex(AudioSystem::stream_type stream, int index) {     ...       return mpPolicyManager->setStreamVolumeIndex(stream, index); } 

将音量控制参数传给音频策略管理器。

10.6 音频投掷
文件： frameworks/base/libs/audioflinger/AudioFlinger.cpp

void AudioFlinger::instantiate() {     defaultServiceManager()->addService(             String16("media.audio_flinger"), new AudioFlinger()); } 

注册名为 media.audio_flinger 的服务

AudioFlinger::AudioFlinger()     : BnAudioFlinger(),         mAudioHardware(0), mMasterVolume(1.0f), mMasterMute(false), mNextThreadId(0) {     ... mAudioHardware = AudioHardwareInterface::create(); ... } status_t AudioFlinger::setParameters(int ioHandle, const String8& keyValuePairs) {     ...         result = mAudioHardware->setParameters(keyValuePairs);     ... } 

将参数转向硬件接口去进行处理。

10.6.1 硬件接口
文件： frameworks/base/libs/audioflinger/AudioHardwareInterface.cpp

AudioHardwareInterface* AudioHardwareInterface::create() {    ...    hw = createAudioHardware();    ... } 

调用音频设备。

10.7 音频策略管理器
文件： hardware/msm7k/libaudio/AudioPolicyManager.cpp

extern "C" AudioPolicyInterface* createAudioPolicyManager(AudioPolicyClientInterface *clientInterface) {     return new AudioPolicyManager(clientInterface); } status_t AudioPolicyManager::setStreamVolumeIndex(AudioSystem::stream_type stream, int index) {      ...     for (size_t i = 0; i < mOutputs.size(); i++) {          status_t volStatus = checkAndSetVolume(stream, index, mOutputs.keyAt(i), mOutputs.valueAt(i)->device());         if (volStatus != NO_ERROR) {             status = volStatus;         }     }     return status; } 

设置音量。

10.8 音频设备
文件： hardware/msm7k/libaudio/AudioHardware.cpp

extern "C" AudioHardwareInterface* createAudioHardware (void) {     return new AudioHardware(); } status_t AudioHardware::setParameters(const String8& keyValuePairs) {     AudioParameter param = AudioParameter(keyValuePairs);     String8 value;     String8 key; ...     key = String8(BT_NAME_KEY);     if (param.get(key, value) == NO_ERROR) {        ...     }     return NO_ERROR; } 

处理 setParameters 参数。

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