AudioPolicyService負責音頻策略處理，包括根據手機的各種狀態和器件的存在、插拔狀態、用戶使能狀態，給不同的audio stream選擇不同的輸入輸出設備，控制不同設備的增益等。
代碼層面，該類則主要是維護3個線程looper，通過不同的輔助類，向client提供服務。
AudioPolicyService的相關類關係如下，
同AudioFlinger，APS在audioServer裏啓動。AudioPolicyService有兩種實現方案，由USE_LEGACY_AUDIO_POLICY控制，
如果是LEGACY方法，使用一個ops函數集操作接口，類似驅動模塊的寫法，在AudioPolicyClientImplLegacy.cpp實現所有函數功能，這些函數實際上就是對AF的功能封裝，在其構造函數中初始，這種方法以及廢棄，我們就不具體分析。
另外一種方法，在AudioPolicyService的onFirstRef中，創建瞭如下幾個重要的線程和實例。
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void AudioPolicyService::onFirstRef() {
// start tone playback thread mTonePlaybackThread = new AudioCommandThread(String8("ApmTone"), this); // start audio commands thread mAudioCommandThread = new AudioCommandThread(String8("ApmAudio"), this); // start output activity command thread mOutputCommandThread = new AudioCommandThread(String8("ApmOutput"), this);
mAudioPolicyClient = new AudioPolicyClient(this); mAudioPolicyManager = createAudioPolicyManager(mAudioPolicyClient);
sp<AudioPolicyEffects>audioPolicyEffects = new AudioPolicyEffects(); } |
AudioCommandThread是AudioPolicyService的內部類，繼承自Thread，在其onFirstRef啓動線程，
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void AudioPolicyService::AudioCommandThread::onFirstRef() { run(mName.string(), ANDROID_PRIORITY_AUDIO); } |
它對外提供各種接口，如startOutputCommand，向其隊列發消息，如START_OUTPUT，然後由其threadLoop處理這些消息，這樣的好處是避免消息擁塞，避免調用棧過長，阻塞系統等，代碼結構清晰，系統耦合性也低。
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bool AudioPolicyService::AudioCommandThread::threadLoop() { nsecs_t waitTime = -1;
mLock.lock(); while (!exitPending()) { sp<AudioPolicyService> svc; while (!mAudioCommands.isEmpty() && !exitPending()) { nsecs_t curTime = systemTime(); // commands are sorted by increasing time stamp: execute them from index 0 and up if (mAudioCommands[0]->mTime <= curTime) { sp<AudioCommand> command = mAudioCommands[0]; mAudioCommands.removeAt(0); mLastCommand = command;
switch (command->mCommand) { … case START_OUTPUT: { StartOutputData *data = (StartOutputData *)command->mParam.get(); ALOGV("AudioCommandThread() processing start output %d", data->mIO); svc = mService.promote(); if (svc == 0) { command->mStatus = UNKNOWN_ERROR; break; } mLock.unlock(); command->mStatus = svc->doStartOutput(data->mIO, data->mStream, data->mSession); mLock.lock(); …
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threadLoop主要調用ToneGenerator，AudioSystem，AF,還有自身的功能實現函數AudioPolicyIntefaceImpl來完成相應的消息處理。實際上，APII也只是封裝了對APM（AudioPolicyManager）的調用而已。
AudioPolicyService還有一個NotificationClient子類，提供接口registerClient讓客戶端註冊，貌似只有AS一個客戶，和AF類似。
AudioSystem.cpp(frameworks\av\media\libmedia): af->registerClient(afc);
AudioSystem.cpp(frameworks\av\media\libmedia): ap->registerClient(apc);
AudioSystem.cpp(frameworks\av\media\libmedia): af->registerClient(afc);
I
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void AudioPolicyService::registerClient(const sp<IAudioPolicyServiceClient>& client) {
sp<NotificationClient> notificationClient = new NotificationClient(this, client, uid); ALOGV("registerClient() client %p, uid %d", client.get(), uid);
mNotificationClients.add(uid, notificationClient);
} |
AudioPolicyClient : publicAudioPolicyClientInterface，代碼實現在AudioPolicyClientImpl.cpp，這個類也只是一個功能封裝類，調用了AF，AudioSystem，APS的接口。在APS的構造函數中作爲APM的構造參數傳入，所以它是APM調用AF，AudioSystem，APS的橋樑。
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mAudioPolicyClient = new AudioPolicyClient(this); mAudioPolicyManager = createAudioPolicyManager(mAudioPolicyClient); |
對於APM類，
APS創建了它的實例，自己的文件不怎麼使用它，但通過looper，使用APII來調用APM的功能。我們先分析這些表面的調用關係，之後要思考其背後的設計意圖。
通過後面分析APM，會發現前面圍繞APS講了一堆的策略、架構、彙報關係的東西，其實真正幹活的只有APM，它就是APS架構裏面的碼農，幹了個體力活還不顯眼，畢竟大家喜歡看架構和策略方面的東西。
APM還是有些技能的，首先他有幾個工具，他把他們交給AudioPolicyConfig去管理（在AudioPolicyConfig.h中），
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HwModuleCollection &mHwModules; DeviceVector &mAvailableOutputDevices; DeviceVector &mAvailableInputDevices; sp<DeviceDescriptor> &mDefaultOutputDevices; VolumeCurvesCollection *mVolumeCurves; |
在APM的構造函數裏，
首先從/system/etc/audio_policy_configuration.xml加載相關配置信息，並序列化、以及初始，不再使用/system/etc/audio_policy.conf文件，這裏會用到PolicySerializer和EngineInstance。
後面就是圍繞AudioPolicyConfig管理的幾個類，根據配置文件進行初始化，如，代碼太多，不一一細化。
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AudioPolicyManager::AudioPolicyManager(AudioPolicyClientInterface *clientInterface) {
1.加載配置信息 #ifdef USE_XML_AUDIO_POLICY_CONF mVolumeCurves = new VolumeCurvesCollection(); AudioPolicyConfig config(mHwModules, mAvailableOutputDevices, mAvailableInputDevices, mDefaultOutputDevice, speakerDrcEnabled, static_cast<VolumeCurvesCollection *>(mVolumeCurves)); PolicySerializer serializer; if (serializer.deserialize(AUDIO_POLICY_XML_CONFIG_FILE, config) != NO_ERROR) { config.setDefault(); } #endif
audio_policy::EngineInstance *engineInstance = audio_policy::EngineInstance::getInstance(); mEngine = engineInstance->queryInterface<AudioPolicyManagerInterface>(); mEngine->setObserver(this); status_t status = mEngine->initCheck(); … 2. 加載配置文件裏的模塊，並一一初始化 for (size_t i = 0; i < mHwModules.size(); i++) { mHwModules[i]->mHandle = mpClientInterface->loadHwModule(mHwModules[i]->getName());
2.1 打開輸出流設備 for (size_t j = 0; j < mHwModules[i]->mOutputProfiles.size(); j++) { const sp<IOProfile> outProfile = mHwModules[i]->mOutputProfiles[j]; sp<SwAudioOutputDescriptor> outputDesc = new SwAudioOutputDescriptor(outProfile, mpClientInterface); audio_io_handle_t output = AUDIO_IO_HANDLE_NONE; status_t status = mpClientInterface->openOutput(outProfile->getModuleHandle(), &output, &config, &outputDesc->mDevice, address, &outputDesc->mLatency, outputDesc->mFlags); addOutput(output, outputDesc); setOutputDevice(outputDesc, outputDesc->mDevice, true, 0, NULL, address.string()); } 2.2 打開輸入流設備 for (size_t j = 0; j < mHwModules[i]->mInputProfiles.size(); j++) { const sp<IOProfile> inProfile = mHwModules[i]->mInputProfiles[j]; sp<AudioInputDescriptor> inputDesc = new AudioInputDescriptor(inProfile); audio_io_handle_t input = AUDIO_IO_HANDLE_NONE; status_t status = mpClientInterface->openInput(inProfile->getModuleHandle(), &input, &config, &inputDesc->mDevice, address, AUDIO_SOURCE_MIC, AUDIO_INPUT_FLAG_NONE); }
3.設置輸入輸出狀態和設備使能專題 // make sure all attached devices have been allocated a unique ID for (size_t i = 0; i < mAvailableOutputDevices.size();) { if (!mAvailableOutputDevices[i]->isAttached()) { ALOGW("Output device %08x unreachable", mAvailableOutputDevices[i]->type()); mAvailableOutputDevices.remove(mAvailableOutputDevices[i]); continue; } // The device is now validated and can be appended to the available devices of the engine mEngine->setDeviceConnectionState(mAvailableOutputDevices[i], AUDIO_POLICY_DEVICE_STATE_AVAILABLE); i++; } for (size_t i = 0; i < mAvailableInputDevices.size();) { if (!mAvailableInputDevices[i]->isAttached()) { ALOGW("Input device %08x unreachable", mAvailableInputDevices[i]->type()); mAvailableInputDevices.remove(mAvailableInputDevices[i]); continue; } // The device is now validated and can be appended to the available devices of the engine mEngine->setDeviceConnectionState(mAvailableInputDevices[i], AUDIO_POLICY_DEVICE_STATE_AVAILABLE); i++; }
updateDevicesAndOutputs(); } |
一份完整的audio_policy_configuration.xml如下，可對照這個配置分解來分析APM的構造過程，
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<audioPolicyConfiguration version="1.0" xmlns:xi="http://www.w3.org/2001/XInclude"> <!-- version section contains a “version” tag in the form “major.minor” e.g version=”1.0” -->
<!-- Global configuration Decalaration --> <globalConfiguration speaker_drc_enabled="true"/> <modules> <!-- Primary Audio HAL --> <module name="primary" halVersion="2.0"> <attachedDevices> <item>Earpiece</item> <item>Speaker</item> <item>Telephony Tx</item> <item>Built-In Mic</item> <item>Built-In Back Mic</item> <item>FM Tuner</item> <item>Telephony Rx</item> </attachedDevices> <defaultOutputDevice>Speaker</defaultOutputDevice> <mixPorts> <mixPort name="primary output" role="source" flags="AUDIO_OUTPUT_FLAG_FAST|AUDIO_OUTPUT_FLAG_PRIMARY"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/> </mixPort> <mixPort name="raw" role="source" flags="AUDIO_OUTPUT_FLAG_FAST|AUDIO_OUTPUT_FLAG_RAW"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/> </mixPort> <mixPort name="deep_buffer" role="source" flags="AUDIO_OUTPUT_FLAG_DEEP_BUFFER"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/> </mixPort> <mixPort name="multichannel" role="source" flags="AUDIO_OUTPUT_FLAG_DIRECT"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,16000,22050,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="dynamic"/> </mixPort> <mixPort name="direct_pcm" role="source" flags="AUDIO_OUTPUT_FLAG_DIRECT|AUDIO_OUTPUT_FLAG_DIRECT_PCM"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_2POINT1,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_PENTA,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_6POINT1,AUDIO_CHANNEL_OUT_7POINT1"/> <profile name="" format="AUDIO_FORMAT_PCM_8_24_BIT" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_2POINT1,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_PENTA,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_6POINT1,AUDIO_CHANNEL_OUT_7POINT1"/> <profile name="" format="AUDIO_FORMAT_PCM_24_BIT_PACKED" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_2POINT1,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_PENTA,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_6POINT1,AUDIO_CHANNEL_OUT_7POINT1"/> </mixPort> <mixPort name="compressed_offload" role="source" flags="AUDIO_OUTPUT_FLAG_DIRECT|AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD|AUDIO_OUTPUT_FLAG_NON_BLOCKING"> <profile name="" format="AUDIO_FORMAT_MP3" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_FLAC" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_ALAC" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_2POINT1,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_PENTA,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_6POINT1,AUDIO_CHANNEL_OUT_7POINT1"/> <profile name="" format="AUDIO_FORMAT_APE" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_AAC_LC" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_AAC_HE_V1" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_AAC_HE_V2" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_WMA" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_2POINT1,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_PENTA,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_6POINT1,AUDIO_CHANNEL_OUT_7POINT1"/> <profile name="" format="AUDIO_FORMAT_WMA_PRO" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_2POINT1,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_PENTA,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_6POINT1,AUDIO_CHANNEL_OUT_7POINT1"/> <profile name="" format="AUDIO_FORMAT_VORBIS" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_AAC_ADTS_LC" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_AAC_ADTS_HE_V1" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> <profile name="" format="AUDIO_FORMAT_AAC_ADTS_HE_V2" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000,64000,88200,96000" channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/> </mixPort> <mixPort name="voice_tx" role="source"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000,48000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO"/> </mixPort> <mixPort name="voip_rx" role="source" flags="AUDIO_OUTPUT_FLAG_DIRECT|AUDIO_OUTPUT_FLAG_VOIP_RX"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/> </mixPort>
<mixPort name="primary input" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000" channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/> </mixPort> <mixPort name="surround_sound" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000" channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK,AUDIO_CHANNEL_INDEX_MASK_3,AUDIO_CHANNEL_INDEX_MASK_4,AUDIO_CHANNEL_IN_5POINT1"/> </mixPort> <mixPort name="voice_rx" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000,48000" channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO"/> </mixPort> </mixPorts>
<devicePorts> <!-- Output devices declaration, i.e. Sink DEVICE PORT --> <devicePort tagName="Earpiece" type="AUDIO_DEVICE_OUT_EARPIECE" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_IN_MONO"/> </devicePort> <devicePort tagName="Speaker" role="sink" type="AUDIO_DEVICE_OUT_SPEAKER" address=""> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/> </devicePort> <devicePort tagName="Wired Headset" type="AUDIO_DEVICE_OUT_WIRED_HEADSET" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/> </devicePort> <devicePort tagName="Wired Headphones" type="AUDIO_DEVICE_OUT_WIRED_HEADPHONE" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/> </devicePort> <devicePort tagName="Line" type="AUDIO_DEVICE_OUT_LINE" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/> </devicePort> <devicePort tagName="BT SCO" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/> </devicePort> <devicePort tagName="BT SCO Headset" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO_HEADSET" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/> </devicePort> <devicePort tagName="BT SCO Car Kit" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO_CARKIT" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/> </devicePort> <devicePort tagName="BT SCO All" type="AUDIO_DEVICE_OUT_ALL_SCO" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/> </devicePort> <devicePort tagName="Telephony Tx" type="AUDIO_DEVICE_OUT_TELEPHONY_TX" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO"/> </devicePort> <devicePort tagName="HDMI" type="AUDIO_DEVICE_OUT_AUX_DIGITAL" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,16000,22050,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="dynamic"/> </devicePort> <devicePort tagName="Proxy" type="AUDIO_DEVICE_OUT_PROXY" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,16000,22050,32000,44100,48000,64000,88200,96000,128000,176400,192000" channelMasks="dynamic"/> </devicePort> <devicePort tagName="FM" type="AUDIO_DEVICE_OUT_FM" role="sink"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_MONO,AUDIO_CHANNEL_OUT_STEREO"/> </devicePort>
<devicePort tagName="Built-In Mic" type="AUDIO_DEVICE_IN_BUILTIN_MIC" role="source"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000" channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/> </devicePort> <devicePort tagName="Built-In Back Mic" type="AUDIO_DEVICE_IN_BACK_MIC" role="source"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000" channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/> </devicePort> <devicePort tagName="FM Tuner" type="AUDIO_DEVICE_IN_FM_TUNER" role="source"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000" channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO"/> </devicePort> <devicePort tagName="Wired Headset Mic" type="AUDIO_DEVICE_IN_WIRED_HEADSET" role="source"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000" channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/> </devicePort> <devicePort tagName="BT SCO Headset Mic" type="AUDIO_DEVICE_IN_BLUETOOTH_SCO_HEADSET" role="source"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_IN_MONO"/> </devicePort> <devicePort tagName="Telephony Rx" type="AUDIO_DEVICE_IN_TELEPHONY_RX" role="source"> <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="8000,16000,48000" channelMasks="AUDIO_CHANNEL_IN_MONO"/> </devicePort> </devicePorts> <!-- route declaration, i.e. list all available sources for a given sink --> <routes> <route type="mix" sink="Earpiece" sources="primary output,raw,deep_buffer,direct_pcm,compressed_offload,voip_rx"/> <route type="mix" sink="Speaker" sources="primary output,raw,deep_buffer,direct_pcm,compressed_offload,voip_rx"/> <route type="mix" sink="Wired Headset" sources="primary output,raw,deep_buffer,direct_pcm,compressed_offload,voip_rx"/> <route type="mix" sink="Wired Headphones" sources="primary output,raw,deep_buffer,direct_pcm,compressed_offload,voip_rx"/> <route type="mix" sink="Line" sources="primary output,raw,deep_buffer,direct_pcm,compressed_offload,voip_rx"/> <route type="mix" sink="HDMI" sources="primary output,raw,deep_buffer,multichannel,direct_pcm,compressed_offload"/> <route type="mix" sink="Proxy" sources="primary output,raw,deep_buffer,multichannel,direct_pcm,compressed_offload"/> <route type="mix" sink="FM" sources="primary output"/> <route type="mix" sink="BT SCO All" sources="primary output,raw,deep_buffer,direct_pcm,compressed_offload,voip_rx"/> <route type="mix" sink="Telephony Tx" sources="voice_tx"/> <route type="mix" sink="primary input" sources="Wired Headset Mic,BT SCO Headset Mic,FM Tuner,Telephony Rx"/> <route type="mix" sink="surround_sound" sources="Built-In Mic,Built-In Back Mic"/> <route type="mix" sink="voice_rx" sources="Telephony Rx"/> </routes>
</module>
<!-- A2dp Audio HAL --> <xi:include href="a2dp_audio_policy_configuration.xml"/>
<!-- Usb Audio HAL --> <xi:include href="usb_audio_policy_configuration.xml"/>
<!-- Remote Submix Audio HAL --> <xi:include href="r_submix_audio_policy_configuration.xml"/>
</modules> <!-- End of Modules section -->
<!-- Volume section -->
<xi:include href="audio_policy_volumes.xml"/> <xi:include href="default_volume_tables.xml"/>
<!-- End of Volume section -->
</audioPolicyConfiguration> |
APM類的繼承關係：
AudioPolicyInterface—AudioPolicyManagerBase—AudioPolicyManagerDefault
AudioPolicyInterface—AudioPolicyManager-- AudioPolicyManagerCustom
AudioPolicyClientInterface--
AudioPolicyManagerBase
getDeviceForStrategy 根據路由策略，按一定優先順序選取不同的設備類型，對應用來講，不用關心手機的各種狀態和器件的存在、插拔狀態、用戶使能狀態。
mAvailableOutputDevices表明了當前device能支持哪些輸出設備，在AudioPolicyManagerBase構造時初始，在setDeviceConnectionState中更新。
mAvailableInputDevices表明了當前device能支持哪些輸入設備，在defaultAudioPolicyConfig時初始，在setDeviceConnectionState中更新。
代碼裏還有這樣一套APM,應該是legacy的，被廢棄了，
AudioPolicyManager.cpp(hardware\qcom\audio\policy_hal)
AudioPolicyInterface.h (hardware\libhardware_legacy\include\hardware_legacy)
Audio_policy_hal.cpp (hardware\libhardware_legacy\audio)
AudioPolicyManagerCustom
APS裏各種元素的對應關係（一對一或一對多的關係）：
System -- audiointerfaces
Audiointerface -- outputs
Output -- devices
Stream Type -- PlaybackThread --device
APS的概述分析就到這裏，細節部分要結合具體的調用流程分析。
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