浅析live555媒体库之实现实时码流预览

前面已经介绍了，通过live555来实现媒体文件的播放。这篇主要和大家说一下实时流的通过live555的播放。

相对之前的文件流，这里实时流只需要多实现一个子类：通过继承RTSPServer类来实现一些自己的相关操作。

如：有客户端请求过来的时候，需要先通过lookupServerMediaSession找到对应的session，这里可以定义自己的streamName，也就是url后面按个串，。如果没有找到，则新建生成自己需要的不同的session，还有填充自己的SDP信息等等操作。

继承RTSPServer的子类实现如下：具体的一些实现可以参考RTSPServer的实现，只需要修改填充自己的session的即可。

#include "DemoH264RTSPServer.h"#include "DemoH264Interface.h"#include "DemoH264MediaSubsession.h"DemoH264RTSPServer* DemoH264RTSPServer::createNew(UsageEnvironment& env,  Port rtspPort, UserAuthenticationDatabase* authDatabase, unsigned reclamationTestSeconds){int rtspSock = -1;rtspSock = setUpOurSocket(env, rtspPort);if(rtspSock == -1 ){DBG_LIVE555_PRINT("setUpOurSocket failed\n");return NULL;}return new DemoH264RTSPServer(env, rtspSock, rtspPort, authDatabase, reclamationTestSeconds);}DemoH264RTSPServer::DemoH264RTSPServer(UsageEnvironment& env, int ourSock, Port rtspPort, UserAuthenticationDatabase* authDatabase,unsigned reclamationTestSeconds):RTSPServer(env, ourSock, rtspPort, authDatabase, reclamationTestSeconds), fRTSPServerState(true){ DBG_LIVE555_PRINT("create DemoH264RTSPServer \n");}DemoH264RTSPServer::~DemoH264RTSPServer(){}ServerMediaSession* DemoH264RTSPServer::lookupServerMediaSession(const char* streamName){// streamName, 为URL地址后面的字符串 如 // rtsp://10.0.2.15/streamNameCH00StreamType00, 则streamName = "streamNameCH00StreamType00";// 当客户端发来url请求时，可以解析streamName来判断请求那个通道的哪种码流// 1 解析url 我这里不处理，可以自己回调接口进来处理int channelNO   = 0;  // 通道号int streamType  = 0;  // 码流类型int videoType   = 1;  // 视频 or 音频int requestType = 0;  // 请求类型 实时预览 or 回放ServerMediaSession* sms = NULL;switch(requestType){case 0:  // realtime sms = RTSPServer::lookupServerMediaSession(streamName);if ( NULL == sms ){sms = ServerMediaSession::createNew(envir(), streamName, NULL, NULL);DemoH264MediaSubsession *session = DemoH264MediaSubsession::createNew(envir(), streamType, videoType, channelNO, false);sms->addSubsession(session);}break;case 1:// play backDBG_LIVE555_PRINT("play back request !\n");break;default:DBG_LIVE555_PRINT("unknown  request type!\n");break;}this->addServerMediaSession(sms);return sms;}DemoH264RTSPServer::DemoH264RTSPClientSession* DemoH264RTSPServer::createNewClientSession(unsigned clientSessionID, int clientSocket, struct sockaddr_in clientAddr){DemoH264RTSPServer::DemoH264RTSPClientSession* client = new DemoH264RTSPClientSession(*this, clientSessionID, clientSocket, clientAddr);fClientSessionList.push_back(client);DBG_LIVE555_PRINT("add client session success!\n");return client;}int DemoH264RTSPServer::stopDemoH264RTSPServer(){// 删除所有的客户端的sessionstd::list<DemoH264RTSPServer::DemoH264RTSPClientSession*> ::iterator pos =this->fClientSessionList.begin();for(pos; pos != this->fClientSessionList.end(); pos ++ ){DemoH264RTSPServer::DemoH264RTSPClientSession* tmp = *pos;delete tmp;}delete this; //return 0;}DemoH264RTSPServer::DemoH264RTSPClientSession::DemoH264RTSPClientSession(DemoH264RTSPServer& rtspServer,unsigned clietnSessionID, int clientSocket, struct sockaddr_in clientAddr):RTSPServer::RTSPClientSession(rtspServer, clietnSessionID, clientSocket, clientAddr){}DemoH264RTSPServer::DemoH264RTSPClientSession::~DemoH264RTSPClientSession(){/*std::list<DemoH264RTSPServer::DemoH264RTSPClientSession*> ::iterator pos =((DemoH264RTSPServer&)fOurServer).fClientSessionList.begin();for(pos; pos != ((DemoH264RTSPServer&)fOurServer).fClientSessionList.end(); pos ++ ){if ((*pos)->fOurSessionId == this->fOurSessionId) {((DemoH264RTSPServer&)fOurServer).fClientSessionList.erase(pos);DBG_LIVE555_PRINT("client session has been delete !\n");break ;}}*/}

因为这些实现，就要请求不同的码流类型，主次码流，或者音频视频这些，所以Source和Session的子类实现也得作相应的修改：

#include "DemoH264FrameSource.h"#include "DemoH264Interface.h"DemoH264FrameSource::DemoH264FrameSource(UsageEnvironment& env, long sourceHandle, int sourceType):FramedSource(env), fSourceHandle(sourceHandle), fLastBufSize(0), fLeftDataSize(0), fSourceType(sourceType), fFirstFrame(1){// 打开流媒体文件，在实时流时，这里就是开始传送流之前的一些准备工作fDataBuf = (char*)malloc(2*1024*1024);if(fDataBuf == NULL ){DBG_LIVE555_PRINT(" create source data buf failed!\n");}}DemoH264FrameSource::~DemoH264FrameSource(){if(fDataBuf){free(fDataBuf);fDataBuf = NULL;}}DemoH264FrameSource* DemoH264FrameSource::createNew(UsageEnvironment& env, int streamType, int channelNO, int sourceType){//通过streamType和channelNO来创建source，向前端请求对应的码流//  long sourceHandle = openStreamHandle(channelNO, streamType);if(sourceHandle == 0){DBG_LIVE555_PRINT("open the source stream failed!\n");return NULL;}DBG_LIVE555_PRINT("create H264FrameSource !\n");return new DemoH264FrameSource(env, sourceHandle, sourceType);}/* 获取需要读取文件的总长度，live555对每次数据的发送有长度限制 */long filesize(FILE *stream){long curpos, length;curpos = ftell(stream);fseek(stream, 0L, SEEK_END);length = ftell(stream);fseek(stream, curpos, SEEK_SET);return length;}void DemoH264FrameSource::doGetNextFrame(){int ret = 0;//调用设备接口获取一帧数据if (fLeftDataSize == 0){ret = getStreamData(fSourceHandle, fDataBuf,&fLastBufSize, &fLeftDataSize,fSourceType);if (ret <= 0){DBG_LIVE555_PRINT("getStreamData failed!\n");return;}}int fNewFrameSize = fLeftDataSize;if(fNewFrameSize > fMaxSize){ // the fMaxSize data fFrameSize = fMaxSize;fNumTruncatedBytes = fNewFrameSize - fMaxSize;fLeftDataSize = fNewFrameSize - fMaxSize;// 注意memmove函数的用法，允许内存空间叠加的memmove(fTo, fDataBuf, fFrameSize); memmove(fDataBuf, fDataBuf+fMaxSize, fLeftDataSize);} else { //all the data fFrameSize = fNewFrameSize;fLeftDataSize = 0;         memmove(fTo, fDataBuf, fFrameSize);}gettimeofday(&fPresentationTime, NULL);if (fFirstFrame){fDurationInMicroseconds = 40000;nextTask() = envir().taskScheduler().scheduleDelayedTask(100000, (TaskFunc*)FramedSource::afterGetting, this);fFirstFrame = 0;}else{FramedSource::afterGetting(this);}}void DemoH264FrameSource::doStopGetFrame(){closeStreamHandle(fSourceHandle);}

session的子类实现

#include "DemoH264MediaSubsession.h"#include "DemoH264FrameSource.h"#include "DemoH264Interface.h"#include "H264VideoStreamFramer.hh"#include "H264VideoRTPSink.hh"DemoH264MediaSubsession::DemoH264MediaSubsession(UsageEnvironment& env, int streamType, int videoType, int channelNO, bool reuseFirstSource, portNumBits initalNumPort):OnDemandServerMediaSubsession(env, reuseFirstSource), fStreamType(streamType), fVideoType(videoType), fChannelNO(channelNO){}DemoH264MediaSubsession::~DemoH264MediaSubsession(){}DemoH264MediaSubsession* DemoH264MediaSubsession::createNew(UsageEnvironment& env, int streamType, int videoType, int channelNO, bool reuseFirstSource, portNumBits initalNumPort){DemoH264MediaSubsession* sms = new DemoH264MediaSubsession(env, streamType, videoType, channelNO, reuseFirstSource, initalNumPort);return sms;}FramedSource* DemoH264MediaSubsession::createNewStreamSource(unsigned clientsessionId, unsigned& estBitrate){DBG_LIVE555_PRINT("create new stream source !\n");//这里根据实际请求的类型创建不同的source对象if(fVideoType == 0x01){ // H264 video estBitrate = 2000; // kbps DemoH264FrameSource * source = DemoH264FrameSource::createNew(envir(), fStreamType, fChannelNO, 0);if ( source == NULL ){DBG_LIVE555_PRINT("create source failed videoType:%d!\n", fVideoType );return NULL;}return H264VideoStreamFramer::createNew(envir(), source);}else if ( fVideoType == 0x2) {// Mpeg-4 video  }else if( fVideoType == 0x04){ // G711 audio estBitrate = 128; // kbps DemoH264FrameSource * source = DemoH264FrameSource::createNew(envir(), fStreamType, fChannelNO, 1);if ( source == NULL ){DBG_LIVE555_PRINT("create source failed videoType:%d!\n", fVideoType );return NULL;}return source;}else { // unknow type}return NULL;}RTPSink* DemoH264MediaSubsession::createNewRTPSink(Groupsock* rtpGroupsock, unsigned char rtpPayloadTypeIfDynamic, FramedSource* inputSource){// 这里可以根据类型的不同创建不同sink // 根据实际开发需要，继承不同的子类DBG_LIVE555_PRINT("createNewRTPnk videoType:%d!\n", fVideoType );if( fVideoType == 0x01){return H264VideoRTPSink::createNew(envir(), rtpGroupsock, rtpPayloadTypeIfDynamic);}else if( fVideoType == 0x02){ //  Mpeg-4}else if(fVideoType == 0x04){// G711 audio}else { // unknow type ;return NULL;}}/* 根据开发实际情况填写SDP信息 *//*char const* DemoH264MediaSubsession::sdpLines(){// create sdp info return  fSDPLines;}*/

最后一个Interface的类，主要是封装一些live555的处理操作以及实时获取码流数据的接口(自己可以根据实际情况写成回调或者其他，看怎么实现方便)，方便其他地方的调用。

#include "DemoH264Interface.h"#include "DemoH264RTSPServer.h"/*打开实时码流句柄*/long openStreamHandle(int channelNO, int streamType){//开始实时流的一些准备工作:获取此类型实时码流的句柄，方便后面直接get码流// 我这里测试，所以还是用自己定义的文件码流来读，不过每次都是读一帧数据// 文件流格式为 FrameHeader_S + H264 + FrameHeader_S + H264 ...FILE* fp = fopen("stream264file.h264", "rb+");if (NULL == fp ){DBG_LIVE555_PRINT("open streamhandle failed!\n");return -1;}return (long)fp;}/*实时获取一帧数据*/int getStreamData(long lHandle, char* buf, unsigned* bufsize, unsigned* leftbufsize, int sourcetype){if(lHandle <= 0){DBG_LIVE555_PRINT(" lHandle error !\n");return -1;}FrameHead_S stFrameHead;memset(&stFrameHead, 0, sizeof(FrameHead_S));FILE* fp = (FILE*)lHandle;int readlen = 0;// 1、先读取一帧数据的头信息readlen = fread(&stFrameHead, 1, sizeof(FrameHead_S), fp);if( readlen != sizeof(FrameHead_S)){DBG_LIVE555_PRINT(" read Frame Header Failed !\n");return -1;}//2、获取一帧H264实时数据if(stFrameHead.FrameLen > 2*1024*1024) // 在source中databuf指分配了2M{DBG_LIVE555_PRINT("data is too long:framlen=%d\n", stFrameHead.FrameLen);//重新分配内存处理return 0;}readlen = fread(buf, 1, stFrameHead.FrameLen, fp);if(readlen != stFrameHead.FrameLen){DBG_LIVE555_PRINT("read Frame rawdata Failed!\n");return -1;}return stFrameHead.FrameLen;}/*关闭码流句柄*/void closeStreamHandle(long lHandle){//一些关闭码流的清理工作fclose((FILE*)lHandle);}DemoH264Interface* DemoH264Interface::m_Instance = NULL;DemoH264Interface* DemoH264Interface::createNew(){if(NULL == m_Instance){m_Instance = new DemoH264Interface();}return m_Instance;}DemoH264Interface::DemoH264Interface(){m_liveServerFlag = false;}DemoH264Interface::~DemoH264Interface(){}void DemoH264Interface::InitLive555(void *param){//初始化DBG_LIVE555_PRINT(" ~~~~Init live555 stream\n");// Begin by setting up the live555 usage environment m_scheduler = BasicTaskScheduler::createNew();m_env = BasicUsageEnvironment::createNew(*m_scheduler);#if ACCESS_CONTROL   // 认证m_authDB = new UserAuthenticationDatabase;m_authDB->addUserRecord("username", "password");#endif m_rtspServer = NULL;m_rtspServerPortNum = 554; // 可以修改m_liveServerFlag = true;}int DemoH264Interface::startLive555(){if( !m_liveServerFlag){DBG_LIVE555_PRINT("Not Init the live server !\n");return -1; }DBG_LIVE555_PRINT(" ~~~~Start live555 stream\n");// 建立RTSP服务m_rtspServer = DemoH264RTSPServer::createNew(*m_env, m_rtspServerPortNum, m_authDB);if( m_rtspServer == NULL){// *m_env << " create RTSPServer Failed:" << m_env->getResultMsg() << "\n";DBG_LIVE555_PRINT("create RTSPServer Failed:%s\n", m_env->getResultMsg());return -1;}// loop and not come back~m_env->taskScheduler().doEventLoop();return 0;}int DemoH264Interface::stopLive555(){DBG_LIVE555_PRINT(" ~~~~stop live555 stream\n");if(m_liveServerFlag){if(m_rtspServer)m_rtspServer->stopDemoH264RTSPServer();m_liveServerFlag = false;}}

最后相当于一个demo调用程序：

#include <stdio.h>#include "DemoH264Interface.h"int main(int argc, char* argv[]){// Init// 添加一些需要设置的rtsp服务信息，如用户名，密码 端口等，通过参数传递void* param = NULL;DemoH264Interface::createNew()->InitLive555(param);// start if( -1 == DemoH264Interface::createNew()->startLive555()){DBG_LIVE555_PRINT(" start live555 moudle failed!\n");return 0;}//stop DemoH264Interface::createNew()->stopLive555();return 0;}

完成这些操作后，我在Windows下测试是能正常预览的j结果如下：

但是在linux系统下貌似不行，出了问题，错误如下：

未找到stream，排查了几天也没查出来原因，在网上看了其他网友的的解惑，貌似说trackId不对，但是我此处ID只有一个，应该不会引起这个问题的，估计病因不在这里，

因为没有研究源码的实现，所以暂时未能定位到问题，希望有遇到的知道缘由的大侠能留言告诉我，我将万分感谢。

上面代码的完整路径可以到这里下载：live555完整代码