gdb调试RTSPClient，分析流程之一

注意如果想让某程序可以被gdb调试，编译的时候就必须加上 gcc 或者g++ -g 命令

live555有专门配置为gdb的配置文件！只需配置即可

gdb binFile 调试某个可执行文件

liqinghan@ubuntu:~/work/live/testProgs$ gdb ./testRTSPClient

run/r argv参数 运行程序

(gdb) run rtsp://192.168.1.2:8554/11.mkv

break/b class::func(type,type,..) 设置某个类的函数断点

(gdb) break DummySink::afterGettingFrame(void*,unsigned , unsigned,struct timeval,unsigned)

(gdb) info b

Num Type Disp Enb Address What

1 breakpoint keep y <PENDING> DummySink::afterGettingFrame(void*,unsigned , unsigned,struct timeval,unsigned)

break func 设置函数断点

info break查看断点

watch expr当expr变化时，停止运行。

continue/c 继续执行

p 查看变量值

s 单步调试（进入函数）

n 单步调试（不进函数）

d 删除指定编号的某个断点（使用info列出的断点）

如下：

(gdb) info break

Num Type Disp Enb Address What

2 hw watchpoint keep y DummySink::afterGettingFrame(void*,unsigned,unsigned,struct timeval,unsigned)

3 breakpoint keep y <PENDING> DummySink::afterGettingFrame(void*,unsigned,unsigned,struct timeval,unsigned)

4 breakpoint keep y 0x0804954e in DummySink::continuePlaying()

at testRTSPClient.cpp:523

那么Num就是编号

break lineNum也可以，执行到当前文件的行号

break 491

9 breakpoint keep y 0x08049ff4 in DummySink::afterGettingFrame(void*, unsigned int, unsigned int, timeval, unsigned int) at testRTSPClient.cpp:491

break 500

10 breakpoint keep y 0x08049e3a in DummySink::afterGettingFrame(unsigned int, unsigned int, timeval, unsigned int) at testRTSPClient.cpp:500

bt 查看函数堆栈

finish 退出函数

typedef void (afterGettingFunc)(void* clientData, unsigned frameSize,

unsigned numTruncatedBytes,

struct timeval presentationTime,

unsigned durationInMicroseconds);

经过调试可以知道RTSPClinet的执行顺序：

1、DummySink::afterGettingFrame(void*, unsigned int, unsigned int, timeval, unsigned int)

2、DummySink::afterGettingFrame(unsigned int, unsigned int, timeval, unsigned int)

//已经得到下一帧数据，用户自己要做的事情，比如调用函数输出视频帧，以及帧信息。用户可以在启动RTSP Client的时候注册一个函数，然后在这个里面调用这个函数，输出这视频帧，即可！

3、DummySink::continuePlaying()

continuPlaying注册afterGettingFrame(void*, unsigned int, unsigned int, timeval, unsigned int)函数，

fSource->getNextFrame(fReceiveBuffer, DUMMY_SINK_RECEIVE_BUFFER_SIZE,

afterGettingFrame, this,

onSourceClosure, this); //获取下一帧数据

void FramedSource::getNextFrame(unsigned char* to, unsigned maxSize,

afterGettingFunc* afterGettingFunc,

void* afterGettingClientData,

onCloseFunc* onCloseFunc,

void* onCloseClientData) {

doGetNextFrame();//MultiFramedRTPSource::doGetNextFrame

}

void MultiFramedRTPSource::doGetNextFrame() {

if (!fAreDoingNetworkReads) {

// Turn on background read handling of incoming packets:

fAreDoingNetworkReads = True;

TaskScheduler::BackgroundHandlerProc* handler

= (TaskScheduler::BackgroundHandlerProc*)&networkReadHandler;

fRTPInterface.startNetworkReading(handler);

}

fSavedTo = fTo;

fSavedMaxSize = fMaxSize;

fFrameSize = 0; // for now

fNeedDelivery = True;

doGetNextFrame1();

}

void MultiFramedRTPSource::doGetNextFrame1() {

...

nextPacket->use(fTo, fMaxSize, frameSize, fNumTruncatedBytes,

fCurPacketRTPSeqNum, fCurPacketRTPTimestamp,

fPresentationTime, fCurPacketHasBeenSynchronizedUsingRTCP,

fCurPacketMarkerBit);

...

}

类继承关系如下图所示