转载请注明：https://www.jianshu.com/p/0cb16c896c36
以RK3399为例
相关数据结构：
中心主题.png
OMX::allocateNode -> new OMXNodeInstance
-> OMXMaster::makeComponentInstance -> 从名称插件map中查到名字对应的插件 OMXPluginBase *plugin = mPluginByComponentName.valueAt(index) -> plugin->makeComponentInstance
-> RKOMXPlugin::makeComponentInstance 如果用到了插件libstagefrighthw.so
->对Vector mCores循环 mCores存着编码器和解码器各一
-> 调用core->mGetHandle句柄
-> Rockchip_OMX_Core: RKOMX_GetHandle(pHandle, cComponentName, pAppData, pCallBacks)
创建ROCKCHIP_OMX_COMPONENT *loadComponent 对象,
loadComponent->libName = "libomxvpu_enc.so", loadComponent->componentName = "rk.omx_enc"
-> Rockchip_OMX_Component_Register: Rockchip_OMX_ComponentLoad(loadComponent)
-> dlopen(libomxvpu_enc.so) -> dlsym("Rockchip_OMX_ComponentConstructor") 对应代码位于hardware_rockchip\omx_il\component\video\enc
-> Rkvpu_OMX_Venc: Rockchip_OMX_ComponentConstructor
-> Rockchip_OMX_Basecomponent: Rockchip_OMX_BaseComponent_Constructor(OMX_HANDLETYPE hComponent)
->构建变量ROCKCHIP_OMX_BASECOMPONENT *pRockchipComponent, pOMXComponent->pComponentPrivate=pRockchipComponent
->创建互斥量：Rockchip_OSAL_SemaphoreCreate(&pRockchipComponent->msgSemaphoreHandle)，
Rockchip_OSAL_MutexCreate(&pRockchipComponent->compMutex)，
Rockchip_OSAL_SignalCreate(&pRockchipComponent->abendStateEvent)
->Rockchip_OSAL_QueueCreate(&pRockchipComponent->messageQ, MAX_QUEUE_ELEMENTS);创建消息队列
-> Rockchip_OSAL_ThreadCreate(&pRockchipComponent->hMessageHandler, Rockchip_OMX_MessageHandlerThread, pOMXComponent); 创建消息处理线程Rockchip_OMX_MessageHandlerThread
-> 设置几个函数指针
pOMXComponent->GetComponentVersion = &Rockchip_OMX_GetComponentVersion;
pOMXComponent->SendCommand = &Rockchip_OMX_SendCommand; //用于给消息队列发送指令
pOMXComponent->GetState = &Rockchip_OMX_GetState;
pOMXComponent->SetCallbacks = &Rockchip_OMX_SetCallbacks;
pOMXComponent->UseEGLImage = &Rockchip_OMX_UseEGLImage;
->>>>>>Rockchip_OMX_Basecomponent: Rockchip_OMX_BaseComponent_Constructor end
->Rockchip_OMX_Baseport: Rockchip_OMX_Port_Constructor(pOMXComponent)
-> pRockchipComponent = (ROCKCHIP_OMX_BASECOMPONENT *)pOMXComponent->pComponentPrivate
-> 设置版本号，port数量为ALL_PORT_NUM = 2， INPUT_PORT_INDEX = 1
INIT_SET_SIZE_VERSION(&pRockchipComponent->portParam, OMX_PORT_PARAM_TYPE);
pRockchipComponent->portParam.nPorts = ALL_PORT_NUM;
pRockchipComponent->portParam.nStartPortNumber = INPUT_PORT_INDEX;
pRockchipPort = Rockchip_OSAL_Malloc(sizeof(ROCKCHIP_OMX_BASEPORT) * ALL_PORT_NUM);
-> 构建input port: pRockchipInputPort
pRockchipComponent->pRockchipPort = pRockchipPort; 利用中间变量创建两个队列
pRockchipInputPort = &pRockchipPort[INPUT_PORT_INDEX];
Rockchip_OSAL_QueueCreate(&pRockchipInputPort->bufferQ, MAX_QUEUE_ELEMENTS);
Rockchip_OSAL_QueueCreate(&pRockchipInputPort->securebufferQ, MAX_QUEUE_ELEMENTS);
pRockchipInputPort->extendBufferHeader = Rockchip_OSAL_Malloc(sizeof(ROCKCHIP_OMX_BUFFERHEADERTYPE) * MAX_BUFFER_NUM);
...
-> 构建output buffer : pRockchipOutputPort
-> 给返回参数设置函数指针
pOMXComponent->EmptyThisBuffer = &Rockchip_OMX_EmptyThisBuffer;
pOMXComponent->FillThisBuffer = &Rockchip_OMX_FillThisBuffer;
->>>>>> Rockchip_OMX_Baseport: Rockchip_OMX_Port_Constructor end
->构建对象 RKVPU_OMX_VIDEOENC_COMPONENT *pVideoEnc
->pVideoEnc->hSharedMemory 这个字段存着"/dev/ion" 这个文件的句柄
->设置 pRockchipComponent 的各种版本信息
pRockchipComponent->hComponentHandle = pVideoEnc(把上一步的共享内存句柄赋值到这里)
pRockchipComponent->bMultiThreadProcess = OMX_TRUE;
pRockchipComponent->codecType = HW_VIDEO_ENC_CODEC;
-> 设置pVideoEnc的信息
pVideoEnc->bFirstFrame = OMX_TRUE;
pVideoEnc->bFirstInput = OMX_TRUE;
pVideoEnc->bFirstOutput = OMX_TRUE;
pVideoEnc->configChange = OMX_FALSE;
pVideoEnc->bStoreMetaData = OMX_FALSE;
pVideoEnc->bPrependSpsPpsToIdr = OMX_FALSE;
pVideoEnc->bRkWFD = OMX_FALSE;
pVideoEnc->quantization.nQpI = 4; // I frame quantization parameter
pVideoEnc->quantization.nQpP = 5; // P frame quantization parameter
pVideoEnc->quantization.nQpB = 5; // B frame quantization parameter
//add by xlm for use mpp or vpuapi
pVideoEnc->bIsUseMpp = OMX_FALSE;
pVideoEnc->bIsNewVpu = OMX_TRUE;
-> 初始化input port: pRockchipComponent->pRockchipPort[INPUT_PORT_INDEX]
一堆赋值操作
-> 初始化output port: pRockchipComponent->pRockchipPort[OUTPUT_PORT_INDEX]
一堆赋值操作
-> pOMXComponent 设置一堆函数指针
pOMXComponent->UseBuffer = &Rkvpu_OMX_UseBuffer;
pOMXComponent->AllocateBuffer = &Rkvpu_OMX_AllocateBuffer;
pOMXComponent->FreeBuffer = &Rkvpu_OMX_FreeBuffer;
pOMXComponent->ComponentTunnelRequest = &Rkvpu_OMX_ComponentTunnelRequest;
pOMXComponent->GetParameter = &Rkvpu_OMX_GetParameter;
pOMXComponent->SetParameter = &Rkvpu_OMX_SetParameter;
pOMXComponent->GetConfig = &Rkvpu_OMX_GetConfig;
pOMXComponent->SetConfig = &Rkvpu_OMX_SetConfig;
pOMXComponent->GetExtensionIndex = &Rkvpu_OMX_GetExtensionIndex;
pOMXComponent->ComponentRoleEnum = &Rkvpu_OMX_ComponentRoleEnum;
pOMXComponent->ComponentDeInit = &Rockchip_OMX_ComponentDeInit;
-> pRockchipComponent设置一堆函数指针
pRockchipComponent->rockchip_codec_componentInit = &Rkvpu_Enc_ComponentInit;
pRockchipComponent->rockchip_codec_componentTerminate = &Rkvpu_Enc_Terminate;
pRockchipComponent->rockchip_AllocateTunnelBuffer = &Rkvpu_OMX_AllocateTunnelBuffer;
pRockchipComponent->rockchip_FreeTunnelBuffer = &Rkvpu_OMX_FreeTunnelBuffer;
pRockchipComponent->rockchip_BufferProcessCreate = &Rkvpu_OMX_BufferProcess_Create; //注意这个函数指针，会启动两个线程
pRockchipComponent->rockchip_BufferProcessTerminate = &Rkvpu_OMX_BufferProcess_Terminate;
pRockchipComponent->rockchip_BufferFlush = &Rkvpu_OMX_BufferFlush;
-> 为pVideoEnc中的AVCComponent数组设置参数，????这里比较可疑，没有生效
INIT_SET_SIZE_VERSION(&pVideoEnc->AVCComponent[i], OMX_VIDEO_PARAM_AVCTYPE);
pVideoEnc->AVCComponent[i].nPortIndex = i;
pVideoEnc->AVCComponent[i].eProfile = OMX_VIDEO_AVCProfileBaseline;
pVideoEnc->AVCComponent[i].eLevel = OMX_VIDEO_AVCLevel31;
pVideoEnc->AVCComponent[i].nPFrames = 20;
pVideoEnc->codecId = OMX_VIDEO_CodingAVC;
pRockchipPort->portDefinition.format.video.eCompressionFormat = OMX_VIDEO_CodingAVC;
->设置状态机： pRockchipComponent->currentState = OMX_StateLoaded;
->>>>>>Rkvpu_OMX_Venc: Rockchip_OMX_ComponentConstructor end
->>>>>>Rockchip_OMX_Component_Register: Rockchip_OMX_ComponentLoad(loadComponent) end
rockchip_component 就是调用者传进的参数loadComponent
rockchip_component->libHandle = libHandle;
rockchip_component->pOMXComponent = pOMXComponent;
rockchip_component->rkversion = OMX_COMPILE_INFO;
-> loadComponent->pOMXComponent->SetCallbacks(loadComponent->pOMXComponent, pCallBacks, pAppData)
这里会设置一个回调，回调函数是从OMX中创建的 OMXNodeInstance 对象的 kCallbacks
->>>>>> Rockchip_OMX_Core: RKOMX_GetHandle(pHandle, cComponentName, pAppData, pCallBacks) end
返回给调用者的 pHandle = loadComponent->pOMXComponent
-> 构建 RKOMXComponent comp
comp.mComponent = *component //这里的component就是上一步RKOMX_GetHandle的参数pHandle
comp.mCore = mCores[i];
-> mComponents.push_back(comp); 把组件加入队列
->>>> 循环结束
->>>> RKOMXPlugin::makeComponentInstance结束
-> instance->setHandle(handle) // instance是OMXNodeInstance对象，
这里把上面创建的OMX_COMPONENTTYPE *handle给赋值到OMXNodeInstance：mHandle
->>>> OMX::allocateNode结束