Stagefright中增加Codec支持

方法1：注册Plugin

device/qcom/common/media/media_codecs.xml

<MediaCodecs>
<Encoders>
<!-- Audio Hardware  -->

<MediaCodec name="OMX.google.aac.encoder" type="audio/mp4a-latm" />

<MediaCodec name="OMX.qcom.audio.encoder.aac" type="audio/mp4a-latm" />

...

</Encoders>
<Decoders>

<!-- Audio Hardware  -->
<MediaCodec name="OMX.qcom.audio.decoder.Qcelp13Hw" type="audio/qcelp" >
<Quirk name="requires-global-flush" />
</MediaCodec>
<MediaCodec name="OMX.qcom.audio.decoder.evrchw" type="audio/evrc" >
<Quirk name="requires-global-flush" />
</MediaCodec>

如果是Decoder则在xml文件的Decoder部分加一行描述新加Codec的信息，注意Codec名称必须以OMX.开头：

<MediaCodec name="OMX.my.aac" type="audio/mp4a-latm" />

如果Codec需要初始化，则可以在OMXCodec::configureCodec中加入codec相关的初始化代码：

status_t OMXCodec::configureCodec(const sp<MetaData> &meta) {
...
} else if (meta->findData(kKeyAVCC, &type, &data, &size)) {
// Parse the AVCDecoderConfigurationRecord

unsigned profile, level;
status_t err;
if ((err = parseAVCCodecSpecificData(
data, size, &profile, &level)) != OK) {
ALOGE("Malformed AVC codec specific data.");
return err;
}

QCOMXCodec::checkIfInterlaced((const uint8_t *)data, meta);

实现Plugin并编译成libstagefright_my.so:
OMXMaster.cpp

OMXMaster::OMXMaster()
: mVendorLibHandle(NULL) {
addVendorPlugin();
addPlugin(new SoftOMXPlugin);
}
void OMXMaster::addVendorPlugin() {
addPlugin("libstagefrighthw.so");
}
void OMXMaster::addPlugin(const char *libname) {
mVendorLibHandle = dlopen(libname, RTLD_NOW);

if (mVendorLibHandle == NULL) {
return;
}

typedef OMXPluginBase *(*CreateOMXPluginFunc)();
CreateOMXPluginFunc createOMXPlugin =
(CreateOMXPluginFunc)dlsym(
mVendorLibHandle, "createOMXPlugin");
if (!createOMXPlugin)
createOMXPlugin = (CreateOMXPluginFunc)dlsym(
mVendorLibHandle, "_ZN7android15createOMXPluginEv");

if (createOMXPlugin) {
addPlugin((*createOMXPlugin)());
}
}

void OMXMaster::addPlugin(OMXPluginBase *plugin) {
Mutex::Autolock autoLock(mLock);

mPlugins.push_back(plugin);

OMX_U32 index = 0;

char name[128];
OMX_ERRORTYPE err;
while ((err = plugin->enumerateComponents(
name, sizeof(name), index++)) == OMX_ErrorNone) {
String8 name8(name);

if (mPluginByComponentName.indexOfKey(name8) >= 0) {
ALOGE("A component of name '%s' already exists, ignoring this one.",
name8.string());

continue;
}

mPluginByComponentName.add(name8, plugin);
}

if (err != OMX_ErrorNoMore) {
ALOGE("OMX plugin failed w/ error 0x%08x after registering %d "
"components", err, mPluginByComponentName.size());
}
}

OMX_ERRORTYPE OMXMaster::makeComponentInstance(
const char *name,
const OMX_CALLBACKTYPE *callbacks,
OMX_PTR appData,
OMX_COMPONENTTYPE **component) {
Mutex::Autolock autoLock(mLock);

*component = NULL;

ssize_t index = mPluginByComponentName.indexOfKey(String8(name));

if (index < 0) {
return OMX_ErrorInvalidComponentName;
}

OMXPluginBase *plugin = mPluginByComponentName.valueAt(index);
OMX_ERRORTYPE err =
plugin->makeComponentInstance(name, callbacks, appData, component);

if (err != OMX_ErrorNone) {
return err;
}

mPluginByInstance.add(*component, plugin);

return err;
}

在SoftOMXPlugin.cpp中，增加一行

static const struct {
const char *mName;
const char *mLibNameSuffix;
const char *mRole;

} kComponents[] = {
{ "OMX.google.aac.decoder", "aacdec", "audio_decoder.aac" },
{ "OMX.my.aac", "aac_my", "audio/mp4a-latm" },

然后实现库文件libstagefright_aac_my.so,在其中实现接口函数SoftOMXComponent *(*CreateSoftOMXComponentFunc)(const char *, const OMX_CALLBACKTYPE *, OMX_PTR, OMX_COMPONENTTYPE **);。

方法2：

实现OMXPluginBase接口及函数OMXPluginBase *(*CreateOMXPluginFunc)()，并在media_codecs.xml中加入对应描述。

struct OMXPluginBase {
OMXPluginBase() {}
virtual ~OMXPluginBase() {}

virtual OMX_ERRORTYPE makeComponentInstance(
const char *name,
const OMX_CALLBACKTYPE *callbacks,
OMX_PTR appData,
OMX_COMPONENTTYPE **component) = 0;

virtual OMX_ERRORTYPE destroyComponentInstance(
OMX_COMPONENTTYPE *component) = 0;

virtual OMX_ERRORTYPE enumerateComponents(
OMX_STRING name,
size_t size,
OMX_U32 index) = 0;

virtual OMX_ERRORTYPE getRolesOfComponent(
const char *name,
Vector<String8> *roles) = 0;

private:
OMXPluginBase(const OMXPluginBase &);
OMXPluginBase &operator=(const OMXPluginBase &);
};

方法3：

实现一整套NuPlayer机制+OMX Codec