RTMPdump 源代码分析 1： main()函数

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Ai_Yang 2021-07-12 15:24:22

文章标签 rtmp 文章分类 Java 后端开发

RTMPdump(libRTMP) 源代码分析系列文章：

RTMPdump (libRTMP) 源代码分析3： AMF编码

RTMPdump (libRTMP) 源代码分析6：建立一个流媒体连接 (NetStream部分 1)

RTMPdump (libRTMP) 源代码分析9：接收消息 (Message) (接收视音频数据)

函数调用结构图

使用RTMPdump下载一个流媒体的大致流程是这样的：

2.里面有很多提取信息的代码形如：rtmp.dlg->AppendCInfo("开始初始化Socket...");这些代码是我为了获取RTMP信息而自己加的，并不影响程序的执行。

}
else
{
//获取最后一个关键帧
nStatus = GetLastKeyframe(file, nSkipKeyFrames,
&dSeek, &initialFrame,
&initialFrameType, &nInitialFrameSize);
if (nStatus == RD_FAILED)
{
RTMP_Log(RTMP_LOGDEBUG, "Failed to get last keyframe.");
goto clean;
}
if (dSeek == 0)
{
RTMP_Log(RTMP_LOGDEBUG,
"Last keyframe is first frame in stream, switching from resume to normal mode!");
bResume = FALSE;
}
}
}
//如果输出文件不存在
if (!file)
{
if (bStdoutMode)
{
//直接输出到stdout
file = stdout;
SET_BINMODE(file);
}
else
{
//打开一个文件
//w+b 读写打开或建立一个二进制文件，允许读和写。
//-----------------
rtmp.dlg->AppendCInfo("创建输出文件...");
//-----------------------------
file = fopen(flvFile, "w+b");
if (file == 0)
{
//-----------------
rtmp.dlg->AppendCInfo("创建输出文件失败！");
//-----------------------------
RTMP_LogPrintf("Failed to open file! %s\n", flvFile);
return RD_FAILED;
}
rtmp.dlg->AppendCInfo("成功创建输出文件");
}
}
#ifdef _DEBUG
netstackdump = fopen("netstackdump", "wb");
netstackdump_read = fopen("netstackdump_read", "wb");
#endif
while (!RTMP_ctrlC)
{
RTMP_Log(RTMP_LOGDEBUG, "Setting buffer time to: %dms", bufferTime);
//设置Buffer时间
//-----------------
rtmp.dlg->AppendCInfo("设置缓冲(Buffer)的时间");
//-----------------------------
RTMP_SetBufferMS(&rtmp, bufferTime);
//第一次执行
if (first)
{
first = 0;
RTMP_LogPrintf("开始建立连接！\n");
//-----------------
rtmp.dlg->AppendCInfo("开始建立连接（NetConnection）...");
//-----------------------------
//建立连接(Connect)
if (!RTMP_Connect(&rtmp, NULL))
{
//-----------------
rtmp.dlg->AppendCInfo("建立连接（NetConnection）失败！");
//-----------------------------
nStatus = RD_FAILED;
break;
}
//-----------------
rtmp.dlg->AppendCInfo("成功建立连接（NetConnection）");
//-----------------------------
//RTMP_Log(RTMP_LOGINFO, "已链接...");
// User defined seek offset
if (dStartOffset > 0)
{
// Don't need the start offset if resuming an existing file
if (bResume)
{
RTMP_Log(RTMP_LOGWARNING,
"Can't seek a resumed stream, ignoring --start option");
dStartOffset = 0;
}
else
{
dSeek = dStartOffset;
}
}
// Calculate the length of the stream to still play
if (dStopOffset > 0)
{
// Quit if start seek is past required stop offset
if (dStopOffset <= dSeek)
{
RTMP_LogPrintf("Already Completed\n");
nStatus = RD_SUCCESS;
break;
}
}
//创建流(Stream)（发送connect命令消息后处理传来的数据）
itoa(rtmp.m_inChunkSize,temp,10);
rtmp.dlg->AppendB_R_Info("输入Chunk大小",temp);
itoa(rtmp.m_outChunkSize,temp,10);
rtmp.dlg->AppendB_R_Info("输出Chunk大小",temp);
itoa(rtmp.m_stream_id,temp,10);
rtmp.dlg->AppendB_R_Info("Stream ID",temp);
itoa(rtmp.m_nBufferMS,temp,10);
rtmp.dlg->AppendB_R_Info("Buffer时长（ms）",temp);
itoa(rtmp.m_nServerBW,temp,10);
rtmp.dlg->AppendB_R_Info("ServerBW",temp);
itoa(rtmp.m_nClientBW,temp,10);
rtmp.dlg->AppendB_R_Info("ClientBW",temp);
itoa((int)rtmp.m_fEncoding,temp,10);
rtmp.dlg->AppendB_R_Info("命令消息编码方法",temp);
itoa((int)rtmp.m_fDuration,temp,10);
rtmp.dlg->AppendB_R_Info("时长（s）",temp);
rtmp.dlg->ShowBInfo();
free(temp);
//-----------------
rtmp.dlg->AppendCInfo("开始建立网络流（NetStream）");
//-----------------------------
if (!RTMP_ConnectStream(&rtmp, dSeek))
{
//-----------------
rtmp.dlg->AppendCInfo("建立网络流（NetStream）失败！");
//-----------------
nStatus = RD_FAILED;
break;
}
//-----------------
rtmp.dlg->AppendCInfo("成功建立网络流（NetStream）！");
//-----------------
}
else
{
nInitialFrameSize = 0;
if (retries)
{
RTMP_Log(RTMP_LOGERROR, "Failed to resume the stream\n\n");
if (!RTMP_IsTimedout(&rtmp))
nStatus = RD_FAILED;
else
nStatus = RD_INCOMPLETE;
break;
}
RTMP_Log(RTMP_LOGINFO, "Connection timed out, trying to resume.\n\n");
/* Did we already try pausing, and it still didn't work? */
if (rtmp.m_pausing == 3)
{
/* Only one try at reconnecting... */
retries = 1;
dSeek = rtmp.m_pauseStamp;
if (dStopOffset > 0)
{
if (dStopOffset <= dSeek)
{
RTMP_LogPrintf("Already Completed\n");
nStatus = RD_SUCCESS;
break;
}
}
if (!RTMP_ReconnectStream(&rtmp, dSeek))
{
RTMP_Log(RTMP_LOGERROR, "Failed to resume the stream\n\n");
if (!RTMP_IsTimedout(&rtmp))
nStatus = RD_FAILED;
else
nStatus = RD_INCOMPLETE;
break;
}
}
else if (!RTMP_ToggleStream(&rtmp))
{
RTMP_Log(RTMP_LOGERROR, "Failed to resume the stream\n\n");
if (!RTMP_IsTimedout(&rtmp))
nStatus = RD_FAILED;
else
nStatus = RD_INCOMPLETE;
break;
}
bResume = TRUE;
}
//-----------------
//-----------------
rtmp.dlg->AppendCInfo("开始将媒体数据写入文件");
//-----------------
//下载,写入文件
nStatus = Download(&rtmp, file, dSeek, dStopOffset, duration, bResume,
metaHeader, nMetaHeaderSize, initialFrame,
initialFrameType, nInitialFrameSize,
nSkipKeyFrames, bStdoutMode, bLiveStream, bHashes,
bOverrideBufferTime, bufferTime, &percent);
free(initialFrame);
initialFrame = NULL;
/* If we succeeded, we're done.
*/
if (nStatus != RD_INCOMPLETE || !RTMP_IsTimedout(&rtmp) || bLiveStream)
break;
}
//当下载完的时候
if (nStatus == RD_SUCCESS)
{
//-----------------
rtmp.dlg->AppendCInfo("写入文件完成");
//-----------------
RTMP_LogPrintf("Download complete\n");
}
//没下载完的时候
else if (nStatus == RD_INCOMPLETE)
{
//-----------------
rtmp.dlg->AppendCInfo("写入文件可能不完整");
//-----------------
RTMP_LogPrintf
("Download may be incomplete (downloaded about %.2f%%), try resuming\n",
percent);
}
//后续清理工作
clean:
//-----------------
rtmp.dlg->AppendCInfo("关闭连接");
//-----------------
RTMP_Log(RTMP_LOGDEBUG, "Closing connection.\n");
RTMP_Close(&rtmp);
rtmp.dlg->AppendCInfo("关闭文件");
if (file != 0)
fclose(file);
rtmp.dlg->AppendCInfo("关闭Socket");
CleanupSockets();
#ifdef _DEBUG
if (netstackdump != 0)
fclose(netstackdump);
if (netstackdump_read != 0)
fclose(netstackdump_read);
#endif
return nStatus;
}