rtmpdump代码分析转

weixin_30642869

65人浏览 · 2014-06-13 17:34:00

weixin_30642869 · 2014-06-13 17:34:00 发布

RTMPdump 源代码分析 1： main()函数

rtmpdump 是一个用来处理 RTMP 流媒体的工具包，支持 rtmp://, rtmpt://, rtmpe://, rtmpte://, and rtmps:// 等。

之前在学习RTMP协议的时候，发现没有讲它源代码的，只好自己分析，现在打算把自己学习的成果写出来，可能结果不一定都对，

先暂且记录一下。

使用RTMPdump下载一个流媒体的大致流程是这样的：

RTMP_Init(); //初始化结构体

InitSockets(); //初始化Socket

RTMP_ParseURL(); //解析输入URL

RTMP_SetupStream(); //一些设置

fopen(); //打开文件，准备写入

RTMP_Connect(); //建立NetConnection

RTMP_ConnectStream(); //建立NetStream

Download(); //下载函数

RTMP_Close(); //关闭连接

fclose(); //关闭文件

CleanupSockets(); //清理Socket

其中Download()主要是使用RTMP_Read()进行下载的。

注：可以参考：RTMP流媒体播放过程

下面贴上自己注释的RTMPDump源代码。注意以下几点：

1.此RTMPDump已经被移植进VC 2010 的 MFC的工程，所以main()函数已经被改名为rtmpdump()，而且参数也改了，传进来一个MFC窗口的句柄。

不过功能没怎么改（控制台程序移植到MFC以后，main()就不是程序的入口了，所以main()名字改成什么是无所谓的）

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。

int rtmpdump(LPVOID lpParam,int argc,char **argv)

{

extern char *optarg;

//一定要设置，否则只能运行一次

extern int optind;

optind=0;

int nStatus = RD_SUCCESS;

double percent = 0;

double duration = 0.0;

int nSkipKeyFrames = DEF_SKIPFRM; // skip this number of keyframes when resuming

int bOverrideBufferTime = FALSE; // if the user specifies a buffer time override this is true

int bStdoutMode = TRUE; // if true print the stream directly to stdout, messages go to stderr

int bResume = FALSE; // true in resume mode

uint32_t dSeek = 0; // seek position in resume mode, 0 otherwise

uint32_t bufferTime = DEF_BUFTIME;

// meta header and initial frame for the resume mode (they are read from the file and compared with

// the stream we are trying to continue

char *metaHeader = 0;

uint32_t nMetaHeaderSize = 0;

// video keyframe for matching

char *initialFrame = 0;

uint32_t nInitialFrameSize = 0;

int initialFrameType = 0; // tye: audio or video

AVal hostname = { 0, 0 };

AVal playpath = { 0, 0 };

AVal subscribepath = { 0, 0 };

int port = -1;

int protocol = RTMP_PROTOCOL_UNDEFINED;

int retries = 0;

int bLiveStream = FALSE; // 是直播流吗? then we can't seek/resume

int bHashes = FALSE; // display byte counters not hashes by default

long int timeout = DEF_TIMEOUT; // timeout connection after 120 seconds

uint32_t dStartOffset = 0; // 非直播流搜寻点seek position in non-live mode

uint32_t dStopOffset = 0;

RTMP rtmp = { 0 };

AVal swfUrl = { 0, 0 };

AVal tcUrl = { 0, 0 };

AVal pageUrl = { 0, 0 };

AVal app = { 0, 0 };

AVal auth = { 0, 0 };

AVal swfHash = { 0, 0 };

uint32_t swfSize = 0;

AVal flashVer = { 0, 0 };

AVal sockshost = { 0, 0 };

#ifdef CRYPTO

int swfAge = 30; /* 30 days for SWF cache by default */

int swfVfy = 0;

unsigned char hash[RTMP_SWF_HASHLEN];

#endif

char *flvFile = 0;

signal(SIGINT, sigIntHandler);

signal(SIGTERM, sigIntHandler);

#ifndef WIN32

signal(SIGHUP, sigIntHandler);

signal(SIGPIPE, sigIntHandler);

signal(SIGQUIT, sigIntHandler);

#endif

RTMP_debuglevel = RTMP_LOGINFO;

//首先搜寻“ --quiet”选项

int index = 0;

while (index < argc)

{

if (strcmp(argv[index], "--quiet") == 0

|| strcmp(argv[index], "-q") == 0)

RTMP_debuglevel = RTMP_LOGCRIT;

index++;

}

#define RTMPDUMP_VERSION "1.0"

RTMP_LogPrintf("RTMP流媒体下载 %s\n", RTMPDUMP_VERSION);

RTMP_LogPrintf

("2012 雷霄骅中国传媒大学/信息工程学院/通信与信息系统/数字电视技术\n");

//RTMP_LogPrintf("输入 -h 获取命令选项\n");

RTMP_Init(&rtmp);



//句柄-----------------------------

rtmp.dlg=(CSpecialPRTMPDlg *)lpParam;

//---------------------------------



//----------------------

rtmp.dlg->AppendCInfo("开始初始化Socket...");

//-----------------------------

if (!InitSockets())

{

//----------------------

rtmp.dlg->AppendCInfo("初始化Socket失败！");

//-----------------------------

RTMP_Log(RTMP_LOGERROR, "Couldn't load sockets support on your platform, exiting!");

return RD_FAILED;

}



//----------------------

rtmp.dlg->AppendCInfo("成功初始化Socket");

//-----------------------------

/* sleep(30); */

int opt;

/* struct option longopts[] = {

{"help", 0, NULL, 'h'},

{"host", 1, NULL, 'n'},

{"port", 1, NULL, 'c'},

{"socks", 1, NULL, 'S'},

{"protocol", 1, NULL, 'l'},

{"playpath", 1, NULL, 'y'},

{"playlist", 0, NULL, 'Y'},

{"rtmp", 1, NULL, 'r'},

{"swfUrl", 1, NULL, 's'},

{"tcUrl", 1, NULL, 't'},

{"pageUrl", 1, NULL, 'p'},

{"app", 1, NULL, 'a'},

{"auth", 1, NULL, 'u'},

{"conn", 1, NULL, 'C'},

#ifdef CRYPTO

{"swfhash", 1, NULL, 'w'},

{"swfsize", 1, NULL, 'x'},

{"swfVfy", 1, NULL, 'W'},

{"swfAge", 1, NULL, 'X'},

#endif

{"flashVer", 1, NULL, 'f'},

{"live", 0, NULL, 'v'},

{"flv", 1, NULL, 'o'},

{"resume", 0, NULL, 'e'},

{"timeout", 1, NULL, 'm'},

{"buffer", 1, NULL, 'b'},

{"skip", 1, NULL, 'k'},

{"subscribe", 1, NULL, 'd'},

{"start", 1, NULL, 'A'},

{"stop", 1, NULL, 'B'},

{"token", 1, NULL, 'T'},

{"hashes", 0, NULL, '#'},

{"debug", 0, NULL, 'z'},

{"quiet", 0, NULL, 'q'},

{"verbose", 0, NULL, 'V'},

{0, 0, 0, 0}

};*/

//分析命令行参数，注意用法。

//选项都是一个字母，后面有冒号的代表该选项还有相关参数

//一直循环直到获取所有的opt

while ((opt =

getopt/*_long*/(argc, argv,

"hVveqzr:s:t:p:a:b:f:o:u:C:n:c:l:y:Ym:k:d:A:B:T:w:x:W:X:S:#"/*,

longopts, NULL*/)) != -1)

{

//不同的选项做不同的处理

switch (opt)

{

case 'h':

usage(argv[0]);

return RD_SUCCESS;

#ifdef CRYPTO

case 'w':

{

int res = hex2bin(optarg, &swfHash.av_val);

if (res != RTMP_SWF_HASHLEN)

{

swfHash.av_val = NULL;

RTMP_Log(RTMP_LOGWARNING,

"Couldn't parse swf hash hex string, not hexstring or not %d bytes, ignoring!", RTMP_SWF_HASHLEN);

}

swfHash.av_len = RTMP_SWF_HASHLEN;

break;

}

case 'x':

{

int size = atoi(optarg);

if (size <= 0)

{

RTMP_Log(RTMP_LOGERROR, "SWF Size must be at least 1, ignoring\n");

}

else

{

swfSize = size;

}

break;

}

case 'W':

STR2AVAL(swfUrl, optarg);

swfVfy = 1;

break;

case 'X':

{

int num = atoi(optarg);

if (num < 0)

{

RTMP_Log(RTMP_LOGERROR, "SWF Age must be non-negative, ignoring\n");

}

else

{

swfAge = num;

}

}

break;

#endif

case 'k':

nSkipKeyFrames = atoi(optarg);

if (nSkipKeyFrames < 0)

{

RTMP_Log(RTMP_LOGERROR,

"Number of keyframes skipped must be greater or equal zero, using zero!");

nSkipKeyFrames = 0;

}

else

{

RTMP_Log(RTMP_LOGDEBUG, "Number of skipped key frames for resume: %d",nSkipKeyFrames);

}

break;

case 'b':

{

int32_t bt = atol(optarg);

if (bt < 0)

{

RTMP_Log(RTMP_LOGERROR,

"Buffer time must be greater than zero, ignoring the specified value %d!",

bt);

}

else

{

bufferTime = bt;

bOverrideBufferTime = TRUE;

}

break;

}

//直播流

case 'v':

//----------------

rtmp.dlg->AppendCInfo("该RTMP的URL是一个直播流");

//----------------

bLiveStream = TRUE; // no seeking or resuming possible!

break;

case 'd':

STR2AVAL(subscribepath, optarg);

break;

case 'n':

STR2AVAL(hostname, optarg);

break;

case 'c':

port = atoi(optarg);

break;

case 'l':

protocol = atoi(optarg);

if (protocol < RTMP_PROTOCOL_RTMP || protocol > RTMP_PROTOCOL_RTMPTS)

{

RTMP_Log(RTMP_LOGERROR, "Unknown protocol specified: %d", protocol);

return RD_FAILED;

}

break;

case 'y':

STR2AVAL(playpath, optarg);

break;

case 'Y':

RTMP_SetOpt(&rtmp, &av_playlist, (AVal *)&av_true);

break;

//路径参数-r

case 'r':

{

AVal parsedHost, parsedApp, parsedPlaypath;

unsigned int parsedPort = 0;

int parsedProtocol = RTMP_PROTOCOL_UNDEFINED;

//解析URL。注optarg指向参数（URL）

RTMP_LogPrintf("RTMP URL : %s\n",optarg);

//----------------

rtmp.dlg->AppendCInfo("解析RTMP的URL...");

//----------------

if (!RTMP_ParseURL

(optarg, &parsedProtocol, &parsedHost, &parsedPort,

&parsedPlaypath, &parsedApp))

{

//----------------

rtmp.dlg->AppendCInfo("解析RTMP的URL失败！");

//----------------

RTMP_Log(RTMP_LOGWARNING, "无法解析 url (%s)!",optarg);

}

else

{

//----------------

rtmp.dlg->AppendCInfo("解析RTMP的URL成功");

//----------------

//把解析出来的数据赋值

if (!hostname.av_len)

hostname = parsedHost;

if (port == -1)

port = parsedPort;

if (playpath.av_len == 0 && parsedPlaypath.av_len)

{

playpath = parsedPlaypath;

}

if (protocol == RTMP_PROTOCOL_UNDEFINED)

protocol = parsedProtocol;

if (app.av_len == 0 && parsedApp.av_len)

{

app = parsedApp;

}

}

break;

}

case 's':

STR2AVAL(swfUrl, optarg);

break;

case 't':

STR2AVAL(tcUrl, optarg);

break;

case 'p':

STR2AVAL(pageUrl, optarg);

break;

case 'a':

STR2AVAL(app, optarg);

break;

case 'f':

STR2AVAL(flashVer, optarg);

break;

//指定输出文件

case 'o':

flvFile = optarg;

if (strcmp(flvFile, "-"))

bStdoutMode = FALSE;

break;

case 'e':

bResume = TRUE;

break;

case 'u':

STR2AVAL(auth, optarg);

break;

case 'C': {

AVal av;

STR2AVAL(av, optarg);

if (!RTMP_SetOpt(&rtmp, &av_conn, &av))

{

RTMP_Log(RTMP_LOGERROR, "Invalid AMF parameter: %s", optarg);

return RD_FAILED;

}

}

break;

case 'm':

timeout = atoi(optarg);

break;

case 'A':

dStartOffset = (int) (atof(optarg) * 1000.0);

break;

case 'B':

dStopOffset = (int) (atof(optarg) * 1000.0);

break;

case 'T': {

AVal token;

STR2AVAL(token, optarg);

RTMP_SetOpt(&rtmp, &av_token, &token);

}

break;

case '#':

bHashes = TRUE;

break;

case 'q':

RTMP_debuglevel = RTMP_LOGCRIT;

break;

case 'V':

RTMP_debuglevel = RTMP_LOGDEBUG;

break;

case 'z':

RTMP_debuglevel = RTMP_LOGALL;

break;

case 'S':

STR2AVAL(sockshost, optarg);

break;

default:

RTMP_LogPrintf("unknown option: %c\n", opt);

usage(argv[0]);

return RD_FAILED;

break;

}

}

if (!hostname.av_len)

{

RTMP_Log(RTMP_LOGERROR,

"您必须指定主机名(hostname) (--host) 或 url (-r \"rtmp://host[:port]/playpath\") 包含 a hostname");

return RD_FAILED;

}

if (playpath.av_len == 0)

{

RTMP_Log(RTMP_LOGERROR,

"您必须指定播放路径(playpath) (--playpath) 或 url (-r \"rtmp://host[:port]/playpath\") 包含 a playpath");

return RD_FAILED;

}

if (protocol == RTMP_PROTOCOL_UNDEFINED)

{

RTMP_Log(RTMP_LOGWARNING,

"您没有指定协议(protocol) (--protocol) 或 rtmp url (-r), 默认协议 RTMP");

protocol = RTMP_PROTOCOL_RTMP;

}

if (port == -1)

{

RTMP_Log(RTMP_LOGWARNING,"您没有指定端口(port) (--port) 或 rtmp url (-r), 默认端口 1935");

port = 0;

}

if (port == 0)

{

if (protocol & RTMP_FEATURE_SSL)

port = 443;

else if (protocol & RTMP_FEATURE_HTTP)

port = 80;

else

port = 1935;

}

if (flvFile == 0)

{

RTMP_Log(RTMP_LOGWARNING,

"请指定一个输出文件 (-o filename), using stdout");

bStdoutMode = TRUE;

}

if (bStdoutMode && bResume)

{

RTMP_Log(RTMP_LOGWARNING,

"Can't resume in stdout mode, ignoring --resume option");

bResume = FALSE;

}

if (bLiveStream && bResume)

{

RTMP_Log(RTMP_LOGWARNING, "Can't resume live stream, ignoring --resume option");

bResume = FALSE;

}

#ifdef CRYPTO

if (swfVfy)

{

if (RTMP_HashSWF(swfUrl.av_val, (unsigned int *)&swfSize, hash, swfAge) == 0)

{

swfHash.av_val = (char *)hash;

swfHash.av_len = RTMP_SWF_HASHLEN;

}

}

if (swfHash.av_len == 0 && swfSize > 0)

{

RTMP_Log(RTMP_LOGWARNING,

"Ignoring SWF size, supply also the hash with --swfhash");

swfSize = 0;

}

if (swfHash.av_len != 0 && swfSize == 0)

{

RTMP_Log(RTMP_LOGWARNING,

"Ignoring SWF hash, supply also the swf size with --swfsize");

swfHash.av_len = 0;

swfHash.av_val = NULL;

}

#endif

if (tcUrl.av_len == 0)

{

char str[512] = { 0 };

tcUrl.av_len = snprintf(str, 511, "%s://%.*s:%d/%.*s",

RTMPProtocolStringsLower[protocol], hostname.av_len,

hostname.av_val, port, app.av_len, app.av_val);

tcUrl.av_val = (char *) malloc(tcUrl.av_len + 1);

strcpy(tcUrl.av_val, str);

}

int first = 1;

// User defined seek offset

if (dStartOffset > 0)

{

//直播流

if (bLiveStream)

{

RTMP_Log(RTMP_LOGWARNING,"Can't seek in a live stream, ignoring --start option");

dStartOffset = 0;

}

}

//----------------

rtmp.dlg->AppendCInfo("开始初始化RTMP连接的参数...");

//----------------

//设置

RTMP_SetupStream(&rtmp, protocol, &hostname, port, &sockshost, &playpath,

&tcUrl, &swfUrl, &pageUrl, &app, &auth, &swfHash, swfSize,

&flashVer, &subscribepath, dSeek, dStopOffset, bLiveStream, timeout);

//此处设置参数-----------------

rtmp.dlg->AppendCInfo("成功初始化RTMP连接的参数");

//-----------------------------

char *temp=(char *)malloc(MAX_URL_LENGTH);

memcpy(temp,rtmp.Link.hostname.av_val,rtmp.Link.hostname.av_len);

temp[rtmp.Link.hostname.av_len]='\0';

rtmp.dlg->AppendB_R_L_Info("主机名",temp);

itoa(rtmp.Link.port,temp,10);

rtmp.dlg->AppendB_R_L_Info("端口号",temp);

memcpy(temp,rtmp.Link.app.av_val,rtmp.Link.app.av_len);

temp[rtmp.Link.app.av_len]='\0';

rtmp.dlg->AppendB_R_L_Info("应用程序",temp);

memcpy(temp,rtmp.Link.playpath.av_val,rtmp.Link.playpath.av_len);

temp[rtmp.Link.playpath.av_len]='\0';

rtmp.dlg->AppendB_R_L_Info("路径",temp);

//-----------------------------

/* Try to keep the stream moving if it pauses on us */

if (!bLiveStream && !(protocol & RTMP_FEATURE_HTTP))

rtmp.Link.lFlags |= RTMP_LF_BUFX;

off_t size = 0;

// ok,我们必须获得timestamp of the last keyframe (only keyframes are seekable) / last audio frame (audio only streams)

if (bResume)

{

//打开文件，输出的文件(Resume)

nStatus =OpenResumeFile(flvFile, &file, &size, &metaHeader, &nMetaHeaderSize,

&duration);

if (nStatus == RD_FAILED)

goto clean;

if (!file)

{

// file does not exist, so go back into normal mode

bResume = FALSE; // we are back in fresh file mode (otherwise finalizing file won't be done)

}

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;

}

其中InitSocket()代码很简单，初始化了Socket，如下：

// 初始化 sockets

int InitSockets()

{

#ifdef WIN32

WORD version;

WSADATA wsaData;

version = MAKEWORD(1, 1);

return (WSAStartup(version, &wsaData) == 0);

#else

return TRUE;

#endif

}

CleanupSockets()则更简单：

inline void CleanupSockets()

{

#ifdef WIN32

WSACleanup();

#endif

}

Download()函数则比较复杂：

int Download(RTMP * rtmp, // connected RTMP object

FILE * file, uint32_t dSeek, uint32_t dStopOffset, double duration, int bResume, char *metaHeader,

uint32_t nMetaHeaderSize, char *initialFrame, int initialFrameType, uint32_t nInitialFrameSize,

int nSkipKeyFrames, int bStdoutMode, int bLiveStream, int bHashes, int bOverrideBufferTime,

uint32_t bufferTime, double *percent) // percentage downloaded [out]

{

int32_t now, lastUpdate;

int bufferSize = 64 * 1024;

char *buffer = (char *) malloc(bufferSize);

int nRead = 0;

//long ftell(FILE *stream);

//返回当前文件指针

RTMP_LogPrintf("开始下载！\n");

off_t size = ftello(file);

unsigned long lastPercent = 0;

//时间戳

rtmp->m_read.timestamp = dSeek;

*percent = 0.0;

if (rtmp->m_read.timestamp)

{

RTMP_Log(RTMP_LOGDEBUG, "Continuing at TS: %d ms\n", rtmp->m_read.timestamp);

}

//是直播

if (bLiveStream)

{

RTMP_LogPrintf("直播流\n");

}

else

{

// print initial status

// Workaround to exit with 0 if the file is fully (> 99.9%) downloaded

if (duration > 0)

{

if ((double) rtmp->m_read.timestamp >= (double) duration * 999.0)

{

RTMP_LogPrintf("Already Completed at: %.3f sec Duration=%.3f sec\n",

(double) rtmp->m_read.timestamp / 1000.0,

(double) duration / 1000.0);

return RD_SUCCESS;

}

else

{

*percent = ((double) rtmp->m_read.timestamp) / (duration * 1000.0) * 100.0;

*percent = ((double) (int) (*percent * 10.0)) / 10.0;

RTMP_LogPrintf("%s download at: %.3f kB / %.3f sec (%.1f%%)\n",

bResume ? "Resuming" : "Starting",

(double) size / 1024.0, (double) rtmp->m_read.timestamp / 1000.0,

*percent);

}

}

else

{

RTMP_LogPrintf("%s download at: %.3f kB\n",

bResume ? "Resuming" : "Starting", (double) size / 1024.0);

}

}

if (dStopOffset > 0)

RTMP_LogPrintf("For duration: %.3f sec\n", (double) (dStopOffset - dSeek) / 1000.0);

//各种设置参数到rtmp连接

if (bResume && nInitialFrameSize > 0)

rtmp->m_read.flags |= RTMP_READ_RESUME;

rtmp->m_read.initialFrameType = initialFrameType;

rtmp->m_read.nResumeTS = dSeek;

rtmp->m_read.metaHeader = metaHeader;

rtmp->m_read.initialFrame = initialFrame;

rtmp->m_read.nMetaHeaderSize = nMetaHeaderSize;

rtmp->m_read.nInitialFrameSize = nInitialFrameSize;

now = RTMP_GetTime();

lastUpdate = now - 1000;

do{

//从rtmp中把bufferSize（64k）个数据读入buffer

nRead = RTMP_Read(rtmp, buffer, bufferSize);

//RTMP_LogPrintf("nRead: %d\n", nRead);

if (nRead > 0)

{

//函数：size_t fwrite(const void* buffer,size_t size,size_t count,FILE* stream);

//向文件读入写入一个数据块。返回值：返回实际写入的数据块数目

//（1）buffer：是一个指针，对fwrite来说，是要输出数据的地址。

//（2）size：要写入内容的单字节数；　　

//（3）count:要进行写入size字节的数据项的个数；　　

//（4）stream:目标文件指针。　　

//（5）返回实际写入的数据项个数count。

//关键。把buffer里面的数据写成文件

if (fwrite(buffer, sizeof(unsigned char), nRead, file) != (size_t) nRead)

{

RTMP_Log(RTMP_LOGERROR, "%s: Failed writing, exiting!", __FUNCTION__);

free(buffer);

return RD_FAILED;

}

//记录已经写入的字节数

size += nRead;

//RTMP_LogPrintf("write %dbytes (%.1f kB)\n", nRead, nRead/1024.0);

if (duration <= 0) // if duration unknown try to get it from the stream (onMetaData)

duration = RTMP_GetDuration(rtmp);

if (duration > 0)

{

// make sure we claim to have enough buffer time!

if (!bOverrideBufferTime && bufferTime < (duration * 1000.0))

{

bufferTime = (uint32_t) (duration * 1000.0) + 5000; // 再加5s以确保buffertime足够长

RTMP_Log(RTMP_LOGDEBUG,

"Detected that buffer time is less than duration, resetting to: %dms",

bufferTime);

//重设Buffer长度

RTMP_SetBufferMS(rtmp, bufferTime);

//给服务器发送UserControl消息通知Buffer改变

RTMP_UpdateBufferMS(rtmp);

}

//计算百分比

*percent = ((double) rtmp->m_read.timestamp) / (duration * 1000.0) * 100.0;

*percent = ((double) (int) (*percent * 10.0)) / 10.0;

if (bHashes)

{

if (lastPercent + 1 <= *percent)

{

RTMP_LogStatus("#");

lastPercent = (unsigned long) *percent;

}

}

else

{

//设置显示数据的更新间隔200ms

now = RTMP_GetTime();

if (abs(now - lastUpdate) > 200)

{

RTMP_LogStatus("\r%.3f kB / %.2f sec (%.1f%%)",

(double) size / 1024.0,

(double) (rtmp->m_read.timestamp) / 1000.0, *percent);

lastUpdate = now;

}

}

}

else

{

//现在距离开机的毫秒数

now = RTMP_GetTime();

//每间隔200ms刷新一次数据

if (abs(now - lastUpdate) > 200)

{

if (bHashes)

RTMP_LogStatus("#");

else

//size为已写入文件的字节数

RTMP_LogStatus("\r%.3f kB / %.2f sec", (double) size / 1024.0,

(double) (rtmp->m_read.timestamp) / 1000.0);

lastUpdate = now;

}

}

}

#ifdef _DEBUG

else

{

RTMP_Log(RTMP_LOGDEBUG, "zero read!");

}

#endif

} while (!RTMP_ctrlC && nRead > -1 && RTMP_IsConnected(rtmp) && !RTMP_IsTimedout(rtmp));



free(buffer);

if (nRead < 0) //nRead是读取情况

nRead = rtmp->m_read.status;

/* Final status update */

if (!bHashes)

{

if (duration > 0)

{

*percent = ((double) rtmp->m_read.timestamp) / (duration * 1000.0) * 100.0;

*percent = ((double) (int) (*percent * 10.0)) / 10.0;

//输出

RTMP_LogStatus("\r%.3f kB / %.2f sec (%.1f%%)",

(double) size / 1024.0,

(double) (rtmp->m_read.timestamp) / 1000.0, *percent);

}

else

{

RTMP_LogStatus("\r%.3f kB / %.2f sec", (double) size / 1024.0,

(double) (rtmp->m_read.timestamp) / 1000.0);

}

}

RTMP_Log(RTMP_LOGDEBUG, "RTMP_Read returned: %d", nRead);

//读取错误

if (bResume && nRead == -2)

{

RTMP_LogPrintf("Couldn't resume FLV file, try --skip %d\n\n",

nSkipKeyFrames + 1);

return RD_FAILED;

}

//读取正确

if (nRead == -3)

return RD_SUCCESS;

//没读完...

if ((duration > 0 && *percent < 99.9) || RTMP_ctrlC || nRead < 0

|| RTMP_IsTimedout(rtmp))

{

return RD_INCOMPLETE;

}

return RD_SUCCESS;

}

以上内容是我能理解到的rtmpdump.c里面的内容。

原文链接:

http://blog.csdn.net/leixiaohua1020/article/details/12952977