Android中初始化Codec2的具体流程

sp<MediaCodec> MediaCodec::CreateByType(
        const sp<ALooper> &looper, const AString &mime, bool encoder, status_t *err, pid_t pid,
        uid_t uid) {
    sp<AMessage> format;
    return CreateByType(looper, mime, encoder, err, pid, uid, format);
}

sp<MediaCodec> MediaCodec::CreateByType(
        const sp<ALooper> &looper, const AString &mime, bool encoder, status_t *err, pid_t pid,
        uid_t uid, sp<AMessage> format) {
    Vector<AString> matchingCodecs;

    MediaCodecList::findMatchingCodecs(
            mime.c_str(),
            encoder,
            0,
            format,
            &matchingCodecs);

    if (err != NULL) {
        *err = NAME_NOT_FOUND;
    }
    for (size_t i = 0; i < matchingCodecs.size(); ++i) {
        sp<MediaCodec> codec = new MediaCodec(looper, pid, uid);
        AString componentName = matchingCodecs[i];
        status_t ret = codec->init(componentName);
        if (err != NULL) {
            *err = ret;
        }
        if (ret == OK) {
            return codec;
        }
        ALOGD("Allocating component '%s' failed (%d), try next one.",
                componentName.c_str(), ret);
    }
    return NULL;
}

CreateByType(
        const sp<ALooper> &looper, const AString &mime, bool encoder, status_t *err, pid_t pid,
        uid_t uid, sp<AMessage> format)

status_t MediaCodec::init(const AString &name) {
    mResourceManagerProxy->init();
    mInitName = name;
    mCodecInfo.clear();
    bool secureCodec = false;
    const char *owner = "";
    mCodec = mGetCodecBase(name, owner);
    
    if (mIsVideo) {
        if (mCodecLooper == NULL) {
            mCodecLooper = new ALooper;
            mCodecLooper->setName("CodecLooper");
            mCodecLooper->start(false, false, ANDROID_PRIORITY_AUDIO);
        }
        mCodecLooper->registerHandler(mCodec);
    } else {
        mLooper->registerHandler(mCodec);
    }

    mLooper->registerHandler(this);

    mCodec->setCallback(
            std::unique_ptr<CodecBase::CodecCallback>(
                    new CodecCallback(new AMessage(kWhatCodecNotify, this))));
    mBufferChannel = mCodec->getBufferChannel();
    mBufferChannel->setCallback(
            std::unique_ptr<CodecBase::BufferCallback>(
                    new BufferCallback(new AMessage(kWhatCodecNotify, this))));

    sp<AMessage> msg = new AMessage(kWhatInit, this);
    if (mCodecInfo) {
        msg->setObject("codecInfo", mCodecInfo);
        // name may be different from mCodecInfo->getCodecName() if we stripped
        // ".secure"
    }
    msg->setString("name", name);
}

sp<CodecBase> MediaCodec::GetCodecBase(const AString &name, const char *owner) {
    if (owner) {
        if (strcmp(owner, "default") == 0) {
            return new ACodec;
        } else if (strncmp(owner, "codec2", 6) == 0) {
            return CreateCCodec();
        }
    }

    if (name.startsWithIgnoreCase("c2.")) {
        return CreateCCodec();
    } else if (name.startsWithIgnoreCase("omx.")) {
        // at this time only ACodec specifies a mime type.
        return new ACodec;
    } else if (name.startsWithIgnoreCase("android.filter.")) {
        return new MediaFilter;
    } else {
        return NULL;
    }
}

static CodecBase *CreateCCodec() {
    return new CCodec;
}

// CCodec
CCodec::CCodec()
    : mChannel(new CCodecBufferChannel(std::make_shared<CCodecCallbackImpl>(this))),
      mConfig(new CCodecConfig) {
}

class CCodecBufferChannel : public BufferChannelBase;

std::shared_ptr<BufferChannelBase> CCodec::getBufferChannel() {
    return mChannel;
}

mCodec->setCallback(
            std::unique_ptr<CodecBase::CodecCallback>(
                    new CodecCallback(new AMessage(kWhatCodecNotify, this))));

struct CodecBase : public AHandler{
    void setCallback(std::unique_ptr<CodecCallback> &&callback) {
        mCallback = std::move(callback);
    }
protected:
    std::unique_ptr<CodecCallback> mCallback;
}

mBufferChannel->setCallback(
            std::unique_ptr<CodecBase::BufferCallback>(
                    new BufferCallback(new AMessage(kWhatCodecNotify, this))));

class BufferChannelBase {
public:
    void setCallback(std::unique_ptr<CodecBase::BufferCallback> &&callback) {
        mCallback = std::move(callback);
    }
protected:
    std::unique_ptr<CodecBase::BufferCallback> mCallback;
};

frameworks/av/media/codec2

//CCodec.h
class CCodec : public CodecBase {
Mutexed<std::unique_ptr<CCodecConfig>> mConfig;
std::shared_ptr<CCodecBufferChannel> mChannel;
}
//CCodec.cpp
CCodec::CCodec()
: mChannel(new CCodecBufferChannel(std::make_shared<CCodecCallbackImpl>(this))),
    mConfig(new CCodecConfig){}

//Codec2Client::Component : public Codec2Client::Configurable
status_t CCodecConfig::initialize(
            const std::shared_ptr<C2ParamReflector> &client,
            const std::shared_ptr<Codec2Client::Configurable> &configurable);
//具体CCodec::allocate的调用逻辑如下(删除不必要语句):
void CCodec::allocate(const sp<MediaCodecInfo> &codecInfo) {
    if (codecInfo == nullptr) {
        mCallback->onError(UNKNOWN_ERROR, ACTION_CODE_FATAL);
        return;
    }
    ALOGD("allocate(%s)", codecInfo->getCodecName());
    mClientListener.reset(new ClientListener(this));
    AString componentName = codecInfo->getCodecName();
    std::shared_ptr<Codec2Client> client;
    // set up preferred component store to access vendor store parameters
    client = Codec2Client::CreateFromService("default");
    if (client) {
        ALOGI("setting up '%s' as default (vendor) store", client->getServiceName().c_str());
        SetPreferredCodec2ComponentStore(std::make_shared<Codec2ClientInterfaceWrapper>(client));
    }

    std::shared_ptr<Codec2Client::Component> comp;
    c2_status_t status = Codec2Client::CreateComponentByName(
            componentName.c_str(),
            mClientListener,
            &comp,
            &client);
    ALOGI("Created component [%s]", componentName.c_str());
    mChannel->setComponent(comp);
    Mutexed<std::unique_ptr<Config>>::Locked configLocked(mConfig);
    const std::unique_ptr<Config> &config = *configLocked;
    status_t err = config->initialize(mClient->getParamReflector(), comp);
    config->queryConfiguration(comp);
    mCallback->onComponentAllocated(componentName.c_str());
}