源码下载地址:https://github.com/EasyDarwin orwww.easydarwin.org
在博客 在Darwin进行实时视频转发的两种模式 中,我们描述了流媒体服务器对源端音视频转发的两种模式,其中一种#拉模式# 转发,在我们通常的项目中经常会用到,比如在传统视频监控行业,IP摄像机部署在监控内网的各个地点,我们需要将他们进行集中式的管理,并且对外发布,这时候我们就需要用到一台流媒体服务器,能够拉取所需的摄像机的音视频流,并做转化(如RTMP、HTTP等),作为监控内网与公网的中转,提供转发服务。
#转发模块设计
拉模式转发中,转发服务器一方面作为RTSP客户端的角色,向源端摄像机获取音视频数据,另一方面作为服务器的角色,将拉取到的音视频数据,重新作为数据源,分发给正在请求的客户端。这样,我们在设计中需要考虑到以下几点:
QTSS_Error DoDescribe(QTSS_StandardRTSP_Params* inParams) { char* theUriStr = NULL; QTSS_Error err = QTSS_GetValueAsString(inParams->inRTSPRequest, qtssRTSPReqFileName, 0, &theUriStr); Assert(err == QTSS_NoErr); if(err != QTSS_NoErr) return QTSSModuleUtils::SendErrorResponse(inParams->inRTSPRequest, qtssClientBadRequest, 0); QTSSCharArrayDeleter theUriStrDeleter(theUriStr); // 查找配置表,获取摄像机信息结构体 DeviceInfo* pDeviceInfo = parseDevice->GetDeviceInfoByIdName(theUriStr); if(pDeviceInfo == NULL) { // 映射表中没有查到相关信息,返回,RTSP请求交给其他模块处理 return QTSS_RequestFailed; } // 映射信息存在rtsp://218.204.223.237:554/live/1/66251FC11353191F/e7ooqwcfbqjoo80j.sdp RTSPClientSession* clientSes = NULL; // 首先查找RTSPClientSession Hash表是否已经建立了对应摄像机的RTSPClientSession StrPtrLen streamName(theUriStr); OSRef* clientSesRef = sClientSessionMap->Resolve(&streamName); if(clientSesRef != NULL) { clientSes = (RTSPClientSession*)clientSesRef->GetObject(); } else { // 初次建立服务器与摄像机间的交互RTSPClientSession clientSes = NEW RTSPClientSession( SocketUtils::ConvertStringToAddr(pDeviceInfo->m_szIP), pDeviceInfo->m_nPort, pDeviceInfo->m_szSourceUrl, 1, rtcpInterval, 0, theReadInterval, sockRcvBuf, speed, packetPlayHeader, overbufferwindowInK, sendOptions, pDeviceInfo->m_szUser, pDeviceInfo->m_szPassword, theUriStr); // 向摄像机源端发送Describe请求 OS_Error theErr = clientSes->SendDescribe(); if(theErr == QTSS_NoErr){ // 将成功建立的RTSPClientSession注册到sClientSessionMap表中 OS_Error theErr = sClientSessionMap->Register(clientSes->GetRef()); Assert(theErr == QTSS_NoErr); } else{ clientSes->Signal(Task::kKillEvent); return QTSSModuleUtils::SendErrorResponse(inParams->inRTSPRequest, qtssClientNotFound, 0); } //增加一次对RTSPClientSession的无效引用,后面会统一释放 OSRef* debug = sClientSessionMap->Resolve(&streamName); Assert(debug == clientSes->GetRef()); } // 建立转发所用的ReflectorSession,后续流程与QTSSReflectorModule类似 ReflectorSession* theSession = SetupProxySession(inParams, clientSes); if (theSession == NULL) { sClientSessionMap->Release(clientSes->GetRef()); return QTSSModuleUtils::SendErrorResponse(inParams->inRTSPRequest, qtssServerNotImplemented, 0); } }
void RemoveOutput(ReflectorOutput* inOutput, ReflectorSession* inSession, Bool16 killClients) { // 从ReflectorSession中移除RTSPSession Assert(inSession); if (inSession != NULL) { if (inOutput != NULL) inSession->RemoveOutput(inOutput,true); OSMutexLocker locker (sSessionMap->GetMutex()); OSRef* theSessionRef = inSession->GetRef(); if (theSessionRef != NULL) { if (theSessionRef->GetRefCount() == 0) { // 当引用客户端数量为0的时候,通知RTSPClientSession断开与摄像机的连接 RTSPClientSession* proxySession = (RTSPClientSession*)inSession->GetRelaySession(); if(proxySession != NULL) { proxySession->SetReflectorSession(NULL); sClientSessionMap->UnRegister(proxySession->GetRef()); proxySession->Signal(Task::kKillEvent); } inSession->SetRelaySession(NULL); sSessionMap->UnRegister(theSessionRef); delete inSession; } else { qtss_printf("QTSSReflector.cpp:RemoveOutput Release SESSION=%lu RefCount=%d\n",(UInt32)inSession,theSessionRef->GetRefCount()); sSessionMap->Release(theSessionRef); } } } delete inOutput; }
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