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.xml
for (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);//1
if (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
// Modules
ModuleTraits::Collection modules;
status_t status = deserializeCollection<ModuleTraits>(root, &modules, config);//1
if (status != NO_ERROR) {
return status;
}
//设置mHwModules
config->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);//1
if (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:primary
Element 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 input
std::string role = getXmlAttribute(child, Attributes::role);//sink或者source
audio_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IOProfile
addProfile(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
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source
audio_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
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type
audio_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sink
sp<PolicyAudioPort> sink = ctx->findPortByTagName(sinkAttr);//根据解析得到的sink的名字,从ports链表中找到DeviceDescriptor
route->setSink(sink);//将找到的DeviceDescriptor添加到AudioRoute的mSink中
std::string sourcesAttr = getXmlAttribute(cur, Attributes::sources);//解析sources
PolicyAudioPortVector 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IOProfile
sources.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 devices
refreshSupportedDevices();
}
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
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DeviceDescriptor
ctx->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.h
void 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.h
void setHwModules(const HwModuleCollection &hwModules)
{
mHwModules = hwModules;
}
总结
- 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
- 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
- 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
- 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