软解码节点的创建和调用

来源：互联网发布：大数据项目需求分析编辑：程序博客网时间：2024/06/01 09:42

android多媒体框架中，SoftOMXPlugin用来添加和解码节点，用简单的创建流程说明：

1.struct SoftOMXPlugin:public OMXPluginBse{

makeComponentInstance()

{

dlopen("libstagefright_soft_xxx");//必须按照此标准

dlsym("SoftOMXComponent"); //此函数创建解码类

}

};

2. OMXMaster.cpp:: addPlugin(new SoftOMXPlugin);//添加到mPluginByComponentName中

3. OMX.cpp::mMaster(new OMXMaster);

4. MediaPlayerService.cpp::getOMX(){ mOMX = new OMX; }

调用过程：

1. awesomeplayer.cpp::initVideoDecoder()

{

mVideoSource = OMXCodec::Create(,mClient.interface, ); // OMXClient mClient;

}

2. class OMXClient{

public:

status_t connect()

{

sp<IServiceManager> sm = defaultServiceManager();

sp<IBiner> binder = sm->getService(String16("media.player"));

sp<IMediaPlayerService> service = interface_caset<IMediaPlayerService>(binder);

mOMX = service->getOMX();

}

sp<IOMX> interface(){ return mOMX; }

private:

sp<IOMX> mOMX;

};

3. OMXCodec.cpp::create()

{

omx->allocateNode();

}

4. OMX.cpp::allocateNode()

{

mMaster->makeComponentInstance(); //mMaster(new OMXMaster);

}

5. OMXMaster.cpp::makeComponentInstance()

{

OMXPluginBase *plugin = mPluginByComponentName.valueAt(index);

plugin->makeComponentInstance();//调用的是SoftOMXPlugin.cpp

}

两个重要的基类OMXPluginBase.cpp（调用者）和SimpleSoftOMXComponent.cpp（解码节点）

其中struct SimpleSoftOMXComponent: public SoftOMXComponent

例如：

struct SoftFFmpegVideo: public SimpleSoftOMXComponent{

protected:

virtual void onQueueFilled(OMX_U32 portIndex);

xxxx

};

android::SoftOMXComponent *createSoftOMXComponent(const char *name, const OMX_CALLBACKTYPE *callbacks,

OMX_PTR appData, OMX_COMPONENTTYPE **component ){

return new android::SoftFFmpegVideo(name, callbacks, appData, component);

} //实现上述类并被plugin调用

SoftFFmpegVideo.cpp如果想作为plugin添加到以上的流程中，需要编译成libstagefright_soft_ffmpegvdec.so

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