Android 11 Audio音频系统配置文件解析

2024-05-28 20:20
文章标签 android 解析 配置文件 audio 音频系统

本文主要是介绍Android 11 Audio音频系统配置文件解析，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

在AudioPolicyService的启动过程中，会去创建AudioPolicyManager对象，进而去解析配置文件

//frameworks/av/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
AudioPolicyManager::AudioPolicyManager(AudioPolicyClientInterface *clientInterface): AudioPolicyManager(clientInterface, false /*forTesting*/)
{loadConfig();
}

loadConfig

//frameworks/av/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
void AudioPolicyManager::loadConfig() {if (deserializeAudioPolicyXmlConfig(getConfig()) != NO_ERROR) {ALOGE("could not load audio policy configuration file, setting defaults");getConfig().setDefault();}
}

deserializeAudioPolicyXmlConfig

//frameworks/av/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
static status_t deserializeAudioPolicyXmlConfig(AudioPolicyConfig &config) {char audioPolicyXmlConfigFile[AUDIO_POLICY_XML_CONFIG_FILE_PATH_MAX_LENGTH];std::vector<const char*> fileNames;status_t ret;//省略fileNames.push_back(AUDIO_POLICY_XML_CONFIG_FILE_NAME);//AUDIO_POLICY_XML_CONFIG_FILE_NAME:audio_policy_configuration.xmlfor (const char* fileName : fileNames) {for (const auto& path : audio_get_configuration_paths()) {snprintf(audioPolicyXmlConfigFile, sizeof(audioPolicyXmlConfigFile),"%s/%s", path.c_str(), fileName);ret = deserializeAudioPolicyFile(audioPolicyXmlConfigFile, &config);//1if (ret == NO_ERROR) {config.setSource(audioPolicyXmlConfigFile);return ret;}}}return ret;
}

audio_get_configuration_paths返回的路径为“/odm/etc”， “/vendor/etc”，“/system/etc” 。然后遍历这些路径，找到audio_policy_configuration.xml文件，然后调用注释1处的deserializeAudioPolicyFile来解析这个文件

deserializeAudioPolicyFile

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/Serializer.cpp
status_t deserializeAudioPolicyFile(const char *fileName, AudioPolicyConfig *config)
{PolicySerializer serializer;return serializer.deserialize(fileName, config);
}

PolicySerializer::deserialize

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/Serializer.cpp
status_t PolicySerializer::deserialize(const char *configFile, AudioPolicyConfig *config)
{auto doc = make_xmlUnique(xmlParseFile(configFile));xmlNodePtr root = xmlDocGetRootElement(doc.get());//省略：对文件的合法性进行效验// Lets deserialize children// ModulesModuleTraits::Collection modules;status_t status = deserializeCollection<ModuleTraits>(root, &modules, config);//1if (status != NO_ERROR) {return status;}//设置mHwModulesconfig->setHwModules(modules);//省略return android::OK;
}

注释1处，开始解析配置文件中的modules标签。注意modules类型为 ModuleTraits::Collection

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/Serializer.cpp
template <class Trait>
status_t deserializeCollection(const xmlNode *cur,typename Trait::Collection *collection,typename Trait::PtrSerializingCtx serializingContext)
{for (cur = cur->xmlChildrenNode; cur != NULL; cur = cur->next) {const xmlNode *child = NULL;if (!xmlStrcmp(cur->name, reinterpret_cast<const xmlChar*>(Trait::collectionTag))) {child = cur->xmlChildrenNode;} else if (!xmlStrcmp(cur->name, reinterpret_cast<const xmlChar*>(Trait::tag))) {child = cur;}for (; child != NULL; child = child->next) {if (!xmlStrcmp(child->name, reinterpret_cast<const xmlChar*>(Trait::tag))) {auto element = Trait::deserialize(child, serializingContext);//1if (element.isOk()) {status_t status = Trait::addElementToCollection(element, collection);//添加元素} else {return BAD_VALUE;}}}}return NO_ERROR;
}

注释1处，针对不同的Trait类型，就调用不同的子类的deserialize处理。对于modules标签，调用ModuleTraits的deserialize处理。

ModuleTraits::deserialize

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/Serializer.cpp
Return<ModuleTraits::Element> ModuleTraits::deserialize(const xmlNode *cur, PtrSerializingCtx ctx)
{std::string name = getXmlAttribute(cur, Attributes::name);//得到名字,如：primaryElement module = new HwModule(name.c_str(), versionMajor, versionMinor);//创建HwModule对象//开始解析mixPorts标签MixPortTraits::Collection mixPorts;status_t status = deserializeCollection<MixPortTraits>(cur, &mixPorts, NULL);module->setProfiles(mixPorts);//开始解析devicePorts标签DevicePortTraits::Collection devicePorts;status = deserializeCollection<DevicePortTraits>(cur, &devicePorts, NULL);module->setDeclaredDevices(devicePorts);//开始解析routes标签RouteTraits::Collection routes;status = deserializeCollection<RouteTraits>(cur, &routes, module.get());module->setRoutes(routes);//开始解析attachedDevices标签for (const xmlNode *children = cur->xmlChildrenNode; children != NULL;children = children->next) {if (!xmlStrcmp(children->name, reinterpret_cast<const xmlChar*>(childAttachedDevicesTag))) {for (const xmlNode *child = children->xmlChildrenNode; child != NULL;child = child->next) {if (!xmlStrcmp(child->name, reinterpret_cast<const xmlChar*>(childAttachedDeviceTag))) {auto attachedDevice = make_xmlUnique(xmlNodeListGetString(child->doc, child->xmlChildrenNode, 1));if (attachedDevice != nullptr) {sp<DeviceDescriptor> device = module->getDeclaredDevices().getDeviceFromTagName(std::string(reinterpret_cast<const char*>(attachedDevice.get())));ctx->addDevice(device);}}}}//开始解析defaultOutputDevice标签if (!xmlStrcmp(children->name,reinterpret_cast<const xmlChar*>(childDefaultOutputDeviceTag))) {auto defaultOutputDevice = make_xmlUnique(xmlNodeListGetString(children->doc, children->xmlChildrenNode, 1));if (defaultOutputDevice != nullptr) {sp<DeviceDescriptor> device = module->getDeclaredDevices().getDeviceFromTagName(std::string(reinterpret_cast<const char*>(defaultOutputDevice.get())));if (device != 0 && ctx->getDefaultOutputDevice() == 0) {ctx->setDefaultOutputDevice(device);}}}
}

解析mixPorts标签

//vendor/etc/audio_policy_configuration.xml
<mixPorts><mixPort name="primary output" role="source" flags="AUDIO_OUTPUT_FLAG_PRIMARY"><profile name="" format="AUDIO_FORMAT_PCM_16_BIT"samplingRates="44100,48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/></mixPort><mixPort name="spdif_passthrough" role="source" flags="AUDIO_OUTPUT_FLAG_DIRECT"><profile name="" format="AUDIO_FORMAT_PCM_16_BIT"samplingRates="32000,44100,48000"channelMasks="AUDIO_CHANNEL_OUT_STEREO"/><profile name="" format="AUDIO_FORMAT_IEC61937"samplingRates="32000,44100,48000"channelMasks="AUDIO_CHANNEL_OUT_STEREO"/></mixPort><mixPort name="hdmi" role="source" flags="AUDIO_OUTPUT_FLAG_DIRECT"><profile name="" format="AUDIO_FORMAT_PCM_16_BIT"samplingRates="32000,44100,48000,96000,176400,192000"channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_7POINT1"/><profile name="" format="AUDIO_FORMAT_IEC61937"samplingRates="32000,44100,48000,96000,176400,192000"channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_QUAD,AUDIO_CHANNEL_OUT_5POINT1,AUDIO_CHANNEL_OUT_7POINT1"/><profile name=""/></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"/></mixPort></mixPorts>

对于mixPorts标签，会循环调用MixPortTraits的deserialize方法解析其子标签，也就是mixPort

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/Serializer.cpp
Return<MixPortTraits::Element> MixPortTraits::deserialize(const xmlNode *child,PtrSerializingCtx /*serializingContext*/)
{std::string name = getXmlAttribute(child, Attributes::name);//得到名字：primary output，spdif_passthrough，hdmi,primary inputstd::string role = getXmlAttribute(child, Attributes::role);//sink或者sourceaudio_port_role_t portRole = (role == Attributes::roleSource) ?AUDIO_PORT_ROLE_SOURCE : AUDIO_PORT_ROLE_SINK;Element mixPort = new IOProfile(name, portRole);//创建IOProfile对象AudioProfileTraits::Collection profiles;status_t status = deserializeCollection<AudioProfileTraits>(child, &profiles, NULL);//解析mixPort标签下的profile// The audio profiles are in order of listed in audio policy configuration file.// Sort audio profiles accroding to the format.sortAudioProfiles(profiles);mixPort->setAudioProfiles(profiles);//添加到mProfiles链表中//省略

根据解析mixPort得到的name和role 创建IOProfile对象，然后开始解析mixPort标签下的profile ，最后将解析结果添加到mProfiles链表中。来看一下profile 的解析

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/Serializer.cpp
Return<AudioProfileTraits::Element> AudioProfileTraits::deserialize(const xmlNode *cur,PtrSerializingCtx /*serializingContext*/)
{std::string samplingRates = getXmlAttribute(cur, Attributes::samplingRates);//采样率std::string format = getXmlAttribute(cur, Attributes::format);//采样位数std::string channels = getXmlAttribute(cur, Attributes::channelMasks);//通道Element profile = new AudioProfile(formatFromString(format, gDynamicFormat),channelMasksFromString(channels, ","),samplingRatesFromString(samplingRates, ","));//创建AudioProfile对象profile->setDynamicFormat(profile->getFormat() == gDynamicFormat);profile->setDynamicChannels(profile->getChannels().empty());profile->setDynamicRate(profile->getSampleRates().empty());return profile;
}

该部分解析完成后，可得到以下结果：每个mixPort标签都会转化成IOProfile对象，mixPort标签下的profile，都会转化成AudioProfile对象，并将该对象添加到对应IOProfile的mProfiles链表。
回到modules的解析方法中，mixPorts标签解析完成后，调用HwModule的setProfiles保存解析的结果

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/HwModule.cpp
void HwModule::setProfiles(const IOProfileCollection &profiles)
{for (size_t i = 0; i < profiles.size(); i++) {//遍历得到的IOProfileaddProfile(profiles[i]);}
}status_t HwModule::addProfile(const sp<IOProfile> &profile)
{switch (profile->getRole()) {case AUDIO_PORT_ROLE_SOURCE:return addOutputProfile(profile);case AUDIO_PORT_ROLE_SINK:return addInputProfile(profile);case AUDIO_PORT_ROLE_NONE:return BAD_VALUE;}return BAD_VALUE;
}

可以看出，对于role为sink的IOProfile，则添加到HwModule的mInputProfiles中，比如上面场景的primary input。对于role为source的IOProfile，则是添加到mOutputProfiles中，比如上面场景的primary output，hdmi等。比如针对上面的场景，经过解析之后可以得到以下信息
在这里插入图片描述
解析devicePorts标签

<devicePorts><devicePort tagName="Speaker" type="AUDIO_DEVICE_OUT_SPEAKER" role="sink"></devicePort><devicePort tagName="Wired Headset" type="AUDIO_DEVICE_OUT_WIRED_HEADSET" role="sink"></devicePort><devicePort tagName="Wired Headphones" type="AUDIO_DEVICE_OUT_WIRED_HEADPHONE" role="sink"></devicePort><devicePort tagName="BT SCO" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO" role="sink"></devicePort><devicePort tagName="BT SCO Headset" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO_HEADSET" role="sink"></devicePort><devicePort tagName="BT SCO Car Kit" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO_CARKIT" role="sink"></devicePort><devicePort tagName="HDMI Out" type="AUDIO_DEVICE_OUT_AUX_DIGITAL" role="sink"></devicePort><devicePort tagName="SPDIF Out" type="AUDIO_DEVICE_OUT_SPDIF" role="sink"></devicePort><devicePort tagName="Built-In Mic" type="AUDIO_DEVICE_IN_BUILTIN_MIC" role="source"></devicePort><devicePort tagName="Wired Headset Mic" type="AUDIO_DEVICE_IN_WIRED_HEADSET" role="source"></devicePort><devicePort tagName="BT SCO Headset Mic" type="AUDIO_DEVICE_IN_BLUETOOTH_SCO_HEADSET" role="source"></devicePort><devicePort tagName="HDMIIn" type="AUDIO_DEVICE_IN_HDMI" role="source"></devicePort></devicePorts>

对于devicePorts标签，循环调用DevicePortTraits的deserialize来解析其子标签

Return<DevicePortTraits::Element> DevicePortTraits::deserialize(const xmlNode *cur,PtrSerializingCtx /*serializingContext*/)
{std::string name = getXmlAttribute(cur, Attributes::tagName);//得到名字：Speaker，Wired Headset等std::string typeName = getXmlAttribute(cur, Attributes::type);//得到类型std::string role = getXmlAttribute(cur, Attributes::role);//sink或者sourceaudio_port_role_t portRole = (role == Attributes::roleSource) ?AUDIO_PORT_ROLE_SOURCE : AUDIO_PORT_ROLE_SINK;//省略Element deviceDesc = new DeviceDescriptor(type, name, address, encodedFormats);//创建DeviceDescriptor对象AudioProfileTraits::Collection profiles;status_t status = deserializeCollection<AudioProfileTraits>(cur, &profiles, NULL);//解析devicePort标签下的profile标签// The audio profiles are in order of listed in audio policy configuration file.// Sort audio profiles accroding to the format.sortAudioProfiles(profiles);deviceDesc->setAudioProfiles(profiles);//省略

首先解析得到name和type，然后创建DeviceDescriptor对象，最后也是解析profile标签并将得到的AudioProfile添加到对应的DeviceDescriptor对象的mProfiles链表中。解析完成后，回到ModuleTraits::deserialize函数中，调用HwModule的setDeclaredDevices保存解析的结果

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/HwModule.cpp
void HwModule::setDeclaredDevices(const DeviceVector &devices)
{mDeclaredDevices = devices;//保存到mDeclaredDevices中for (size_t i = 0; i < devices.size(); i++) {mPorts.add(devices[i]);//保存到mPorts中}
}

最后将结果保存在HwModule的mDeclaredDevices和mPorts中。针对上面的场景，可以得到以下解析结果
在这里插入图片描述
解析routes标签

<routes><route type="mix" sink="Speaker"sources="primary output"/><route type="mix" sink="Wired Headset"sources="primary output"/><route type="mix" sink="Wired Headphones"sources="primary output"/><route type="mix" sink="BT SCO"sources="primary output"/><route type="mix" sink="BT SCO Headset"sources="primary output"/><route type="mix" sink="BT SCO Car Kit"sources="primary output"/><route type="mix" sink="HDMI Out"sources="primary output,hdmi"/><route type="mix" sink="SPDIF Out"sources="primary output,spdif_passthrough"/><route type="mix" sink="primary input"sources="Built-In Mic,Wired Headset Mic,BT SCO Headset Mic,HDMIIn"/></routes>

对于routes下的子标签，调用RouteTraits的deserialize解析处理

Return<RouteTraits::Element> RouteTraits::deserialize(const xmlNode *cur, PtrSerializingCtx ctx)
{std::string type = getXmlAttribute(cur, Attributes::type);//解析typeaudio_route_type_t routeType = (type == Attributes::typeMix) ?AUDIO_ROUTE_MIX : AUDIO_ROUTE_MUX;Element route = new AudioRoute(routeType);//创建AudioRoute对象std::string sinkAttr = getXmlAttribute(cur, Attributes::sink);//解析sinksp<PolicyAudioPort> sink = ctx->findPortByTagName(sinkAttr);//根据解析得到的sink的名字，从ports链表中找到DeviceDescriptorroute->setSink(sink);//将找到的DeviceDescriptor添加到AudioRoute的mSink中std::string sourcesAttr = getXmlAttribute(cur, Attributes::sources);//解析sourcesPolicyAudioPortVector sources;std::unique_ptr<char[]> sourcesLiteral{strndup(sourcesAttr.c_str(), strlen(sourcesAttr.c_str()))};char *devTag = strtok(sourcesLiteral.get(), ",");while (devTag != NULL) {if (strlen(devTag) != 0) {sp<PolicyAudioPort> source = ctx->findPortByTagName(devTag);//根据source，可以找到对应的IOProfilesources.add(source);}devTag = strtok(NULL, ",");}sink->addRoute(route);//将该route添加到sink的mRoutes链表中for (size_t i = 0; i < sources.size(); i++) {sp<PolicyAudioPort> source = sources.itemAt(i);source->addRoute(route);//将该route添加到source的mRoutes链表中}route->setSources(sources);//将source添加到AudioRoute的mSources中return route;}

该方法主要是解析sink和source，然后根据其名字，分别找到对应的PolicyAudioPort，设置AudioRoute的mSink和mSources。回到ModuleTraits::deserialize函数中，调用HwModule的setRoutes保存解析的结果

//frameworks/av/services/audiopolicy/common/managerdefinitions/src/HwModule.cpp
void HwModule::setRoutes(const AudioRouteVector &routes)
{mRoutes = routes;//将结果保存在mRoutes 中// Now updating the streams (aka IOProfile until now) supported devicesrefreshSupportedDevices();
}

主要是将解析的结果，保存在HwModule的mRoutes 中。针对以上场景，可以得到如下结果
在这里插入图片描述
解析attachedDevices标签

<attachedDevices><item>Speaker</item><item>Built-In Mic</item><item>HDMIIn</item>
</attachedDevices>

attachedDevices标签的解析，就在ModuleTraits::deserialize函数中

for (const xmlNode *children = cur->xmlChildrenNode; children != NULL;children = children->next) {if (!xmlStrcmp(children->name, reinterpret_cast<const xmlChar*>(childAttachedDevicesTag))) {ALOGV("%s: %s %s found", __func__, tag, childAttachedDevicesTag);for (const xmlNode *child = children->xmlChildrenNode; child != NULL;child = child->next) {if (!xmlStrcmp(child->name,reinterpret_cast<const xmlChar*>(childAttachedDeviceTag))) {auto attachedDevice = make_xmlUnique(xmlNodeListGetString(child->doc, child->xmlChildrenNode, 1));if (attachedDevice != nullptr) {sp<DeviceDescriptor> device = module->getDeclaredDevices().getDeviceFromTagName(std::string(reinterpret_cast<const char*>(attachedDevice.get())));//从mDeclaredDevices 链表中根据名字找到DeviceDescriptorctx->addDevice(device);//更加type类型，分别添加到AudioPolicyConfig的mOutputDevices和mInputDevices中}}}}

来看一下addDevice方法

///frameworks/av/services/audiopolicy/common/managerdefinitions/include/AudioPolicyConfig.hvoid addDevice(const sp<DeviceDescriptor> &device){if (audio_is_output_device(device->type())) {mOutputDevices.add(device);} else if (audio_is_input_device(device->type())) {mInputDevices.add(device);}}

解析defaultOutputDevice标签

<defaultOutputDevice>Speaker</defaultOutputDevice>

对于该标签的解析比较简单，主要从mDeclaredDevices 链表中根据名字找到对应的DeviceDescriptor，然后将其赋值给AudioPolicyConfig的mDefaultOutputDevice成员

回到PolicySerializer::deserialize方法，当moudles解析完成后，会将解析得到的HwModule保存在AudioPolicyConfig的mHwModules中

//frameworks/av/services/audiopolicy/common/managerdefinitions/include/AudioPolicyConfig.hvoid setHwModules(const HwModuleCollection &hwModules){mHwModules = hwModules;}

总结

  1. 解析mixPorts标签，每个mixPort子项，都会构建一个IOProfile对象，对于mixPort标签下的每个profile项，都会构建一个AudioProfile对象，并将AudioProfile对象放到对应IOProfile对象的mProfiles中。最后这些IOProfile对象，根据type类型，分别添加到HwModule的mOutputProfiles和mInputProfiles中。并且这些IOProfile也会添加到HwModule的mPorts中
  2. 解析devicePorts标签，每个devicePort都会创建DeviceDescriptor对象，最后这些DeviceDescriptor都会添加到HwModule的mDeclaredDevices和mPorts中
  3. 解析routes标签，对每个route，都会创建AudioRoute对象。分别根据sink和source的名字，从前面得到的mPorts中找到对应项，设置AudioRoute的mSink和mSource，最后将这些AudioRoute添加到HwModule的mRoutes中
  4. AudioPolicyConfig 有几个成员
HwModuleCollection &mHwModules; /**< Collection of Module, with Profiles, i.e. Mix Ports. */
DeviceVector &mOutputDevices;
DeviceVector &mInputDevices;
sp<DeviceDescriptor> &mDefaultOutputDevice;

其中mHwModules保存的是modules标签下的每个HwModule，解析attachedDevices标签时，会根据其名字找到对应的DeviceDescriptor，然后根据这些DeviceDescriptor的type，分别放入mOutputDevices和mInputDevices中。解析defaultOutputDevice标签时，根据名字找到对应的DeviceDescriptor，然后保存在mDefaultOutputDevice中

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