Android 8 AudioPolicy 分析 _Android

关山初度尘未洗，策马扬鞭再奋蹄！这篇文章主要讲述Android 8 AudioPolicy 分析相关的知识，希望能为你提供帮助。
AudioTrack最终会调用AudioPolicyManager::getOutput();

frameworksavservicesaudiopolicymanagerdefaultAudioPolicyManager.cpp audio_io_handle_t AudioPolicyManager::getOutput(audio_stream_type_t stream, uint32_t samplingRate, audio_format_t format, audio_channel_mask_t channelMask, audio_output_flags_t flags, const audio_offload_info_t *offloadInfo) { //APM_AudioPolicyManager: getOutput() device 2, stream 1, samplingRate 0, format 0, channelMask 3, flags 0 // stream = 1, AUDIO_STREAM_SYSTEM, 得到的strategy = STRATEGY_MEDIA routing_strategy strategy = getStrategy(stream); // AUDIO_DEVICE_NONE & AUDIO_DEVICE_OUT_SPEAKER audio_devices_t device = getDeviceForStrategy(strategy, false /*fromCache*/); //APM_AudioPolicyManager: getOutput() device 2, stream 1, samplingRate 0, format 0, channelMask 3, flags 0 ALOGV(" getOutput() device %d, stream %d, samplingRate %d, format %x, channelMask %x, flags %x" , device, stream, samplingRate, format, channelMask, flags); ALOGE(" Liutao getOutput() device %d, stream %d, samplingRate %d, format %x, channelMask %x, flags %x" , device, stream, samplingRate, format, channelMask, flags); return getOutputForDevice(device, AUDIO_SESSION_ALLOCATE, stream, samplingRate, format, channelMask, flags, offloadInfo); }

根据stream获取strategy【Android 8 AudioPolicy 分析】StreamType指PCM的生成类型。是播放电影产生的？还是通话产生的？
STRATEGY指针对某一中stream,该采用的策略。在策略里面，会根据其他信息来具体选定某一个具体的Audio Devices

routing_strategy AudioPolicyManager::getStrategy(audio_stream_type_t stream) const { ALOG_ASSERT(stream != AUDIO_STREAM_PATCH," getStrategy() called for AUDIO_STREAM_PATCH" ); return mEngine-> getStrategyForStream(stream); }// 不同的stream类型对应的stragegy，播放音乐，系统铃声，stream = 1, AUDIO_STREAM_SYSTEM = 1, frameworksavservicesaudiopolicyenginedefaultsrcEngine.cpp routing_strategy Engine::getStrategyForStream(audio_stream_type_t stream) { // stream to strategy mapping switch (stream) { case AUDIO_STREAM_VOICE_CALL: case AUDIO_STREAM_BLUETOOTH_SCO: return STRATEGY_PHONE; case AUDIO_STREAM_RING: case AUDIO_STREAM_ALARM: return STRATEGY_SONIFICATION; case AUDIO_STREAM_NOTIFICATION: return STRATEGY_SONIFICATION_RESPECTFUL; case AUDIO_STREAM_DTMF: return STRATEGY_DTMF; default: ALOGE(" unknown stream type %d" , stream); case AUDIO_STREAM_SYSTEM: // NOTE: SYSTEM stream uses MEDIA strategy because muting music and switching outputs // while key clicks are played produces a poor result case AUDIO_STREAM_MUSIC: return STRATEGY_MEDIA; case AUDIO_STREAM_ENFORCED_AUDIBLE: return STRATEGY_ENFORCED_AUDIBLE; case AUDIO_STREAM_TTS: return STRATEGY_TRANSMITTED_THROUGH_SPEAKER; case AUDIO_STREAM_ACCESSIBILITY: return STRATEGY_ACCESSIBILITY; case AUDIO_STREAM_REROUTING: return STRATEGY_REROUTING; } }frameworksavservicesaudiopolicycommonincludeRoutingStrategy.h enum routing_strategy { STRATEGY_MEDIA, STRATEGY_PHONE, STRATEGY_SONIFICATION, STRATEGY_SONIFICATION_RESPECTFUL, STRATEGY_DTMF, STRATEGY_ENFORCED_AUDIBLE, STRATEGY_TRANSMITTED_THROUGH_SPEAKER, STRATEGY_ACCESSIBILITY, STRATEGY_REROUTING, NUM_STRATEGIES }; // STREAM类型定义 typedef enum { AUDIO_STREAM_DEFAULT = -1, // (-1) AUDIO_STREAM_MIN = 0, AUDIO_STREAM_VOICE_CALL = 0, AUDIO_STREAM_SYSTEM = 1, AUDIO_STREAM_RING = 2, AUDIO_STREAM_MUSIC = 3, AUDIO_STREAM_ALARM = 4, AUDIO_STREAM_NOTIFICATION = 5, AUDIO_STREAM_BLUETOOTH_SCO = 6, AUDIO_STREAM_ENFORCED_AUDIBLE = 7, AUDIO_STREAM_DTMF = 8, AUDIO_STREAM_TTS = 9, AUDIO_STREAM_ACCESSIBILITY = 10, AUDIO_STREAM_REROUTING = 11, AUDIO_STREAM_PATCH = 12, AUDIO_STREAM_PUBLIC_CNT = 11, // (ACCESSIBILITY + 1) AUDIO_STREAM_FOR_POLICY_CNT = 12, // PATCH AUDIO_STREAM_CNT = 13, // (PATCH + 1) } audio_stream_type_t;

根据Strategy获取device

audio_devices_t AudioPolicyManager::getDeviceForStrategy(routing_strategy strategy, bool fromCache) { // Routing // see if we have an explicit route // scan the whole RouteMap, for each entry, convert the stream type to a strategy // (getStrategy(stream)). // if the strategy from the stream type in the RouteMap is the same as the argument above, // and activity count is non-zero and the device in the route descriptor is available // then select this device. for (size_t routeIndex = 0; routeIndex < mOutputRoutes.size(); routeIndex++) { sp< SessionRoute> route = mOutputRoutes.valueAt(routeIndex); routing_strategy routeStrategy = getStrategy(route-> mStreamType); // 判断输入的STRAGEGY是否在系统支持的mOutputRoutes列表里面 if ((routeStrategy == strategy) & & route-> isActive() & & (mAvailableOutputDevices.indexOf(route-> mDeviceDescriptor) > = 0)) { return route-> mDeviceDescriptor-> type(); } }if (fromCache) { ALOGVV(" getDeviceForStrategy() from cache strategy %d, device %x" , strategy, mDeviceForStrategy[strategy]); return mDeviceForStrategy[strategy]; } // 传入的stragegy = STRATEGY_MEDIA return mEngine-> getDeviceForStrategy(strategy); }audio_devices_t Engine::getDeviceForStrategy(routing_strategy strategy) const { DeviceVector availableOutputDevices = mApmObserver-> getAvailableOutputDevices(); DeviceVector availableInputDevices = mApmObserver-> getAvailableInputDevices(); const SwAudioOutputCollection & outputs = mApmObserver-> getOutputs(); return getDeviceForStrategyInt(strategy, availableOutputDevices, availableInputDevices, outputs); }frameworksavservicesaudiopolicyenginedefaultsrcEngine.cpp audio_devices_t Engine::getDeviceForStrategyInt(routing_strategy strategy, DeviceVector availableOutputDevices, DeviceVector availableInputDevices, const SwAudioOutputCollection & outputs) const { uint32_t device = AUDIO_DEVICE_NONE; uint32_t availableOutputDevicesType = availableOutputDevices.types(); bool isFmA2dpConcurrencyOn = property_get_bool(" vendor.fm.a2dp.conc.disabled" , false); // Do not support a2dp device when FM is active based on concurrency property if (isFmA2dpConcurrencyOn & & (availableOutputDevicesType & AUDIO_DEVICE_OUT_FM)) { ALOGV(" FM a2dp concurrency is set, not considering a2dp for device selection" ); availableOutputDevicesType = availableOutputDevicesType & ~AUDIO_DEVICE_OUT_ALL_A2DP; }// 传入的stragegy = STRATEGY_MEDIA = 0 switch (strategy) { // FIXME: STRATEGY_REROUTING follow STRATEGY_MEDIA for now case STRATEGY_REROUTING: case STRATEGY_MEDIA: { uint32_t device2 = AUDIO_DEVICE_NONE; // 是否在打电话 if (isInCall() & & (device == AUDIO_DEVICE_NONE)) { // when in call, get the device for Phone strategy device = getDeviceForStrategy(STRATEGY_PHONE); break; }if (strategy != STRATEGY_SONIFICATION) { // no sonification on remote submix (e.g. WFD) // 查看是否有远程设备 if (availableOutputDevices.getDevice(AUDIO_DEVICE_OUT_REMOTE_SUBMIX, String8(" 0" )) != 0) { device2 = availableOutputDevices.types() & AUDIO_DEVICE_OUT_REMOTE_SUBMIX; } } // 打电话, 并且播放音乐还有系统铃声时的处理 if (isInCall() & & (strategy == STRATEGY_MEDIA)) { device = getDeviceForStrategyInt( STRATEGY_PHONE, availableOutputDevices, availableInputDevices, outputs); break; } // 蓝牙耳机 if ((device2 == AUDIO_DEVICE_NONE) & & (mForceUse[AUDIO_POLICY_FORCE_FOR_MEDIA] != AUDIO_POLICY_FORCE_NO_BT_A2DP) & & (outputs.isA2dpOnPrimary() || (outputs.getA2dpOutput() != 0))) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_BLUETOOTH_A2DP; if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES; } if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER; } } // SPEAKER if ((device2 == AUDIO_DEVICE_NONE) & & (mForceUse[AUDIO_POLICY_FORCE_FOR_MEDIA] == AUDIO_POLICY_FORCE_SPEAKER)) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_SPEAKER; } // 听筒 if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_WIRED_HEADPHONE; } if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_LINE; } // 有线耳机 if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_WIRED_HEADSET; } // USB耳机 if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_USB_HEADSET; } if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_USB_ACCESSORY; } if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_USB_DEVICE; } if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_DGTL_DOCK_HEADSET; } if ((device2 == AUDIO_DEVICE_NONE) & & (strategy != STRATEGY_SONIFICATION) & & (device == AUDIO_DEVICE_NONE)) { // no sonification on aux digital (e.g. HDMI) device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_AUX_DIGITAL; } if ((device2 == AUDIO_DEVICE_NONE) & & (strategy != STRATEGY_SONIFICATION) & & (mForceUse[AUDIO_POLICY_FORCE_FOR_DOCK] == AUDIO_POLICY_FORCE_ANALOG_DOCK)) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_ANLG_DOCK_HEADSET; } if ((device2 == AUDIO_DEVICE_NONE) & & (strategy != STRATEGY_SONIFICATION) & & (device == AUDIO_DEVICE_NONE)) { // no sonification on WFD sink device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_PROXY; } if (device2 == AUDIO_DEVICE_NONE) { device2 = availableOutputDevicesType & AUDIO_DEVICE_OUT_SPEAKER; } int device3 = AUDIO_DEVICE_NONE; // 几个设备同时输出 if (strategy == STRATEGY_MEDIA) { // ARC, SPDIF and AUX_LINE can co-exist with others. device3 = availableOutputDevicesType & AUDIO_DEVICE_OUT_HDMI_ARC; device3 |= (availableOutputDevicesType & AUDIO_DEVICE_OUT_SPDIF); device3 |= (availableOutputDevicesType & AUDIO_DEVICE_OUT_AUX_LINE); }device2 |= device3; // device is DEVICE_OUT_SPEAKER if we come from case STRATEGY_SONIFICATION or // STRATEGY_ENFORCED_AUDIBLE, AUDIO_DEVICE_NONE otherwise device |= device2; // If hdmi system audio mode is on, remove speaker out of output list. if ((strategy == STRATEGY_MEDIA) & & (mForceUse[AUDIO_POLICY_FORCE_FOR_HDMI_SYSTEM_AUDIO] == AUDIO_POLICY_FORCE_HDMI_SYSTEM_AUDIO_ENFORCED)) { device & = ~AUDIO_DEVICE_OUT_SPEAKER; }// for STRATEGY_SONIFICATION: // if SPEAKER was selected, and SPEAKER_SAFE is available, use SPEAKER_SAFE instead if ((strategy == STRATEGY_SONIFICATION) & & (device & AUDIO_DEVICE_OUT_SPEAKER) & & (availableOutputDevicesType & AUDIO_DEVICE_OUT_SPEAKER_SAFE)) { device |= AUDIO_DEVICE_OUT_SPEAKER_SAFE; device & = ~AUDIO_DEVICE_OUT_SPEAKER; } } break; default: ALOGW(" getDeviceForStrategy() unknown strategy: %d" , strategy); break; }if (device == AUDIO_DEVICE_NONE) { ALOGV(" getDeviceForStrategy() no device found for strategy %d" , strategy); device = mApmObserver-> getDefaultOutputDevice()-> type(); ALOGE_IF(device == AUDIO_DEVICE_NONE, " getDeviceForStrategy() no default device defined" ); } ALOGVV(" getDeviceForStrategy() strategy %d, device %x" , strategy, device); return device; }

为设备选择的输出通道// APM_AudioPolicyManager: getOutput() device 2, stream 1, samplingRate 0, format 0, channelMask 3, flags 0

audio_io_handle_t AudioPolicyManager::getOutputForDevice( audio_devices_t device, audio_session_t session, audio_stream_type_t stream, uint32_t samplingRate, audio_format_t format, audio_channel_mask_t channelMask, audio_output_flags_t flags, const audio_offload_info_t *offloadInfo)hardwareqcomaudiohalmsm8916platform.c static int msm_device_to_be_id_internal_codec [][NO_COLS] = { {AUDIO_DEVICE_OUT_EARPIECE,34}, {AUDIO_DEVICE_OUT_SPEAKER,34}, {AUDIO_DEVICE_OUT_WIRED_HEADSET,34}, {AUDIO_DEVICE_OUT_WIRED_HEADPHONE,34}, {AUDIO_DEVICE_OUT_BLUETOOTH_SCO,11}, {AUDIO_DEVICE_OUT_BLUETOOTH_SCO_HEADSET,11}, {AUDIO_DEVICE_OUT_BLUETOOTH_SCO_CARKIT,11}, {AUDIO_DEVICE_OUT_BLUETOOTH_A2DP,-1}, {AUDIO_DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES,-1}, {AUDIO_DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER,-1}, {AUDIO_DEVICE_OUT_AUX_DIGITAL,4}, {AUDIO_DEVICE_OUT_ANLG_DOCK_HEADSET,9}, {AUDIO_DEVICE_OUT_DGTL_DOCK_HEADSET,9}, {AUDIO_DEVICE_OUT_USB_ACCESSORY,-1}, {AUDIO_DEVICE_OUT_USB_DEVICE,-1}, {AUDIO_DEVICE_OUT_USB_HEADSET,-1}, {AUDIO_DEVICE_OUT_REMOTE_SUBMIX,9}, {AUDIO_DEVICE_OUT_PROXY,9}, {AUDIO_DEVICE_OUT_FM,7}, {AUDIO_DEVICE_OUT_FM_TX,8}, {AUDIO_DEVICE_OUT_ALL,-1}, {AUDIO_DEVICE_NONE,-1}, {AUDIO_DEVICE_OUT_DEFAULT,-1}, }; static int msm_device_to_be_id_external_codec [][NO_COLS] = { {AUDIO_DEVICE_OUT_EARPIECE,2}, {AUDIO_DEVICE_OUT_SPEAKER,2}, {AUDIO_DEVICE_OUT_WIRED_HEADSET,41}, {AUDIO_DEVICE_OUT_WIRED_HEADPHONE,41}, {AUDIO_DEVICE_OUT_BLUETOOTH_SCO,11}, {AUDIO_DEVICE_OUT_BLUETOOTH_SCO_HEADSET,11}, {AUDIO_DEVICE_OUT_BLUETOOTH_SCO_CARKIT,11}, {AUDIO_DEVICE_OUT_BLUETOOTH_A2DP,-1}, {AUDIO_DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES,-1}, {AUDIO_DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER,-1}, {AUDIO_DEVICE_OUT_AUX_DIGITAL,4}, {AUDIO_DEVICE_OUT_ANLG_DOCK_HEADSET,9}, {AUDIO_DEVICE_OUT_DGTL_DOCK_HEADSET,9}, {AUDIO_DEVICE_OUT_USB_ACCESSORY,-1}, {AUDIO_DEVICE_OUT_USB_DEVICE,-1}, {AUDIO_DEVICE_OUT_USB_HEADSET,-1}, {AUDIO_DEVICE_OUT_REMOTE_SUBMIX,9}, {AUDIO_DEVICE_OUT_PROXY,9}, {AUDIO_DEVICE_OUT_FM,7}, {AUDIO_DEVICE_OUT_FM_TX,8}, {AUDIO_DEVICE_OUT_ALL,-1}, {AUDIO_DEVICE_NONE,-1}, {AUDIO_DEVICE_OUT_DEFAULT,-1}, };