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