本文记录一个基于libRTMP的发布流媒体的程序。该程序可以将本地FLV文件发布到RTMP流媒体服务器。是最简单的基于libRTMP的流媒体发布示例。
RTMP流程图
使用librtmp发布RTMP流的可以使用两种API：RTMP_SendPacket()和RTMP_Write()。使用RTMP_SendPacket()发布流的时候的函数执行流程图如下图所示。使用RTMP_Write()发布流的时候的函数执行流程图相差不大。
流程图中关键函数的作用如下所列：
InitSockets()：初始化Socket
RTMP_Alloc()：为结构体“RTMP”分配内存。
RTMP_Init()：初始化结构体“RTMP”中的成员变量。
RTMP_SetupURL()：设置输入的RTMP连接的URL。
RTMP_EnableWrite()：发布流的时候必须要使用。如果不使用则代表接收流。
RTMP_Connect()：建立RTMP连接，创建一个RTMP协议规范中的NetConnection。
RTMP_ConnectStream()：创建一个RTMP协议规范中的NetStream。
Delay：发布流过程中的延时，保证按正常播放速度发送数据。
RTMP_SendPacket()：发送一个RTMP数据RTMPPacket。
RTMP_Close()：关闭RTMP连接。
RTMP_Free()：释放结构体“RTMP”。
CleanupSockets()：关闭Socket。
源代码
源代码中包含了使用两种API函数RTMP_SendPacket()和RTMP_Write()发布流媒体的源代码，如下所示。
/**
* Simplest Librtmp Send FLV
* 本程序用于将FLV格式的视音频文件使用RTMP推送至RTMP流媒体服务器。
* This program can send local flv file to net server as a rtmp live stream.
*/
#include
#include
#include
#include
#ifndef WIN32
#include
#endif
#include "librtmp/rtmp_sys.h"
#include "librtmp/log.h"
#define HTON16(x) ((x>>8&0xff)|(x<<8&0xff00))
#define HTON24(x) ((x>>16&0xff)|(x<<16&0xff0000)|(x&0xff00))
#define HTON32(x) ((x>>24&0xff)|(x>>8&0xff00)|\
(x<<8&0xff0000)|(x<<24&0xff000000))
#define HTONTIME(x) ((x>>16&0xff)|(x<<16&0xff0000)|(x&0xff00)|(x&0xff000000))
/*read 1 byte*/
int ReadU8(uint32_t *u8,FILE*fp){
if(fread(u8,1,1,fp)!=1)
return 0;
return 1;
}
/*read 2 byte*/
int ReadU16(uint32_t *u16,FILE*fp){
if(fread(u16,2,1,fp)!=1)
return 0;
*u16=HTON16(*u16);
return 1;
}
/*read 3 byte*/
int ReadU24(uint32_t *u24,FILE*fp){
if(fread(u24,3,1,fp)!=1)
return 0;
*u24=HTON24(*u24);
return 1;
}
/*read 4 byte*/
int ReadU32(uint32_t *u32,FILE*fp){
if(fread(u32,4,1,fp)!=1)
return 0;
*u32=HTON32(*u32);
return 1;
}
/*read 1 byte,and loopback 1 byte at once*/
int PeekU8(uint32_t *u8,FILE*fp){
if(fread(u8,1,1,fp)!=1)
return 0;
fseek(fp,-1,SEEK_CUR);
return 1;
}
/*read 4 byte and convert to time format*/
int ReadTime(uint32_t *utime,FILE*fp){
if(fread(utime,4,1,fp)!=1)
return 0;
*utime=HTONTIME(*utime);
return 1;
}
int InitSockets()
{
WORD version;
WSADATA wsaData;
version=MAKEWORD(2,2);
return (WSAStartup(version, &wsaData) == 0);
}
void CleanupSockets()
{
WSACleanup();
}
//Publish using RTMP_SendPacket()
int publish_using_packet(){
RTMP *rtmp=NULL;
RTMPPacket *packet=NULL;
uint32_t start_time=0;
uint32_t now_time=0;
//the timestamp of the previous frame
long pre_frame_time=0;
long lasttime=0;
int bNextIsKey=1;
uint32_t preTagsize=0;
//packet attributes
uint32_t type=0;
uint32_t datalength=0;
uint32_t timestamp=0;
uint32_t streamid=0;
FILE*fp=NULL;
fp=fopen("cuc_ieschool.flv","rb");
if (!fp){
RTMP_LogPrintf("Open File Error.\n");
CleanupSockets();
return -1;
}
/* set log level */
//RTMP_LogLevel loglvl=RTMP_LOGDEBUG;
//RTMP_LogSetLevel(loglvl);
if (!InitSockets()){
RTMP_LogPrintf("Init Socket Err\n");
return -1;
}
rtmp=RTMP_Alloc();
RTMP_Init(rtmp);
//set connection timeout,default 30s
rtmp->Link.timeout=5;
if(!RTMP_SetupURL(rtmp,"rtmp://localhost/publishlive/livestream"))
{
RTMP_Log(RTMP_LOGERROR,"SetupURL Err\n");
RTMP_Free(rtmp);
CleanupSockets();
return -1;
}
//if unable,the AMF command would be 'play' instead of 'publish'
RTMP_EnableWrite(rtmp);
if (!RTMP_Connect(rtmp,NULL)){
RTMP_Log(RTMP_LOGERROR,"Connect Err\n");
RTMP_Free(rtmp);
CleanupSockets();
return -1;
}
if (!RTMP_ConnectStream(rtmp,0)){
RTMP_Log(RTMP_LOGERROR,"ConnectStream Err\n");
RTMP_Close(rtmp);
RTMP_Free(rtmp);
CleanupSockets();
return -1;
}
packet=(RTMPPacket*)malloc(sizeof(RTMPPacket));
RTMPPacket_Alloc(packet,1024*64);
RTMPPacket_Reset(packet);
packet->m_hasAbsTimestamp = 0;
packet->m_nChannel = 0x04;
packet->m_nInfoField2 = rtmp->m_stream_id;
RTMP_LogPrintf("Start to send data ...\n");
//jump over FLV Header
fseek(fp,9,SEEK_SET);
//jump over previousTagSizen
fseek(fp,4,SEEK_CUR);
start_time=RTMP_GetTime();
while(1)
{
if((((now_time=RTMP_GetTime())-start_time)
<(pre_frame_time)) && bNextIsKey){
//wait for 1 sec if the send process is too fast
//this mechanism is not very good,need some improvement
if(pre_frame_time>lasttime){
RTMP_LogPrintf("TimeStamp:%8lu ms\n",pre_frame_time);
lasttime=pre_frame_time;
}
Sleep(1000);
continue;
}
//not quite the same as FLV spec
if(!ReadU8(&type,fp))
break;
if(!ReadU24(&datalength,fp))
break;
if(!ReadTime(×tamp,fp))
break;
if(!ReadU24(&streamid,fp))
break;
if (type!=0x08&&type!=0x09){
//jump over non_audio and non_video frame，
//jump over next previousTagSizen at the same time
fseek(fp,datalength+4,SEEK_CUR);
continue;
}
if(fread(packet->m_body,1,datalength,fp)!=datalength)
break;
packet->m_headerType = RTMP_PACKET_SIZE_LARGE;
packet->m_nTimeStamp = timestamp;
packet->m_packetType = type;
packet->m_nBodySize = datalength;
pre_frame_time=timestamp;
if (!RTMP_IsConnected(rtmp)){
RTMP_Log(RTMP_LOGERROR,"rtmp is not connect\n");
break;
}
if (!RTMP_SendPacket(rtmp,packet,0)){
RTMP_Log(RTMP_LOGERROR,"Send Error\n");
break;
}
if(!ReadU32(&preTagsize,fp))
break;
if(!PeekU8(&type,fp))
break;
if(type==0x09){
if(fseek(fp,11,SEEK_CUR)!=0)
break;
if(!PeekU8(&type,fp)){
break;
}
if(type==0x17)
bNextIsKey=1;
else
bNextIsKey=0;
fseek(fp,-11,SEEK_CUR);
}
}
RTMP_LogPrintf("\nSend Data Over\n");
if(fp)
fclose(fp);
if (rtmp!=NULL){
RTMP_Close(rtmp);
RTMP_Free(rtmp);
rtmp=NULL;
}
if (packet!=NULL){
RTMPPacket_Free(packet);
free(packet);
packet=NULL;
}
CleanupSockets();
return 0;
}
//Publish using RTMP_Write()
int publish_using_write(){
uint32_t start_time=0;
uint32_t now_time=0;
uint32_t pre_frame_time=0;
uint32_t lasttime=0;
int bNextIsKey=0;
char* pFileBuf=NULL;
//read from tag header
uint32_t type=0;
uint32_t datalength=0;
uint32_t timestamp=0;
RTMP *rtmp=NULL;
FILE*fp=NULL;
fp=fopen("cuc_ieschool.flv","rb");
if (!fp){
RTMP_LogPrintf("Open File Error.\n");
CleanupSockets();
return -1;
}
/* set log level */
//RTMP_LogLevel loglvl=RTMP_LOGDEBUG;
//RTMP_LogSetLevel(loglvl);
if (!InitSockets()){
RTMP_LogPrintf("Init Socket Err\n");
return -1;
}
rtmp=RTMP_Alloc();
RTMP_Init(rtmp);
//set connection timeout,default 30s
rtmp->Link.timeout=5;
if(!RTMP_SetupURL(rtmp,"rtmp://localhost/publishlive/livestream"))
{
RTMP_Log(RTMP_LOGERROR,"SetupURL Err\n");
RTMP_Free(rtmp);
CleanupSockets();
return -1;
}
RTMP_EnableWrite(rtmp);
//1hour
RTMP_SetBufferMS(rtmp, 3600*1000);
if (!RTMP_Connect(rtmp,NULL)){
RTMP_Log(RTMP_LOGERROR,"Connect Err\n");
RTMP_Free(rtmp);
CleanupSockets();
return -1;
}
if (!RTMP_ConnectStream(rtmp,0)){
RTMP_Log(RTMP_LOGERROR,"ConnectStream Err\n");
RTMP_Close(rtmp);
RTMP_Free(rtmp);
CleanupSockets();
return -1;
}
printf("Start to send data ...\n");
//jump over FLV Header
fseek(fp,9,SEEK_SET);
//jump over previousTagSizen
fseek(fp,4,SEEK_CUR);
start_time=RTMP_GetTime();
while(1)
{
if((((now_time=RTMP_GetTime())-start_time)
<(pre_frame_time)) && bNextIsKey){
//wait for 1 sec if the send process is too fast
//this mechanism is not very good,need some improvement
if(pre_frame_time>lasttime){
RTMP_LogPrintf("TimeStamp:%8lu ms\n",pre_frame_time);
lasttime=pre_frame_time;
}
Sleep(1000);
continue;
}
//jump over type
fseek(fp,1,SEEK_CUR);
if(!ReadU24(&datalength,fp))
break;
if(!ReadTime(×tamp,fp))
break;
//jump back
fseek(fp,-8,SEEK_CUR);
pFileBuf=(char*)malloc(11+datalength+4);
memset(pFileBuf,0,11+datalength+4);
if(fread(pFileBuf,1,11+datalength+4,fp)!=(11+datalength+4))
break;
pre_frame_time=timestamp;
if (!RTMP_IsConnected(rtmp)){
RTMP_Log(RTMP_LOGERROR,"rtmp is not connect\n");
break;
}
if (!RTMP_Write(rtmp,pFileBuf,11+datalength+4)){
RTMP_Log(RTMP_LOGERROR,"Rtmp Write Error\n");
break;
}
free(pFileBuf);
pFileBuf=NULL;
if(!PeekU8(&type,fp))
break;
if(type==0x09){
if(fseek(fp,11,SEEK_CUR)!=0)
break;
if(!PeekU8(&type,fp)){
break;
}
if(type==0x17)
bNextIsKey=1;
else
bNextIsKey=0;
fseek(fp,-11,SEEK_CUR);
}
}
RTMP_LogPrintf("\nSend Data Over\n");
if(fp)
fclose(fp);
if (rtmp!=NULL){
RTMP_Close(rtmp);
RTMP_Free(rtmp);
rtmp=NULL;
}
if(pFileBuf){
free(pFileBuf);
pFileBuf=NULL;
}
CleanupSockets();
return 0;
}
int main(int argc, char* argv[]){
//2 Methods:
publish_using_packet();
//publish_using_write();
return 0;
}
运行结果
程序运行后，会将“cuc_ieschool.flv”文件以直播流的形式发布到“rtmp://localhost/publishlive/livestream”的URL。修改文件名称和RTMP的URL可以实现将任意flv文件发布到任意RTMP的URL。