Cannot open camera with OpenCV in Linux - c++

Question

I am using OpenCV 2.4.3 on linux now. And in my /dev/ there is a device called video0 that is working fine with cheese.
Currently I am using the following code to try to access the camera. This code is written in qtcreator and compiled with qmake to include the necessary library. As for the OpenCV library, I downloaded the source code and compiled it according to the instruction on the website on my machine.
++main.cpp:
#include <iostream>
#include <opencv2/opencv.hpp>
#include <cstdlib>
int main(int argc, char** argv) {
int cameraNumber = 0;
if (argc>1)
cameraNumber = atoi(argv[1]);
cv::VideoCapture camera;
camera.open(cameraNumber);
if(!camera.isOpened()) {
std::cerr<<"Error opening camera"<<std::endl;
exit(1);
}
camera.set(CV_CAP_PROP_FRAME_WIDTH,640);
camera.set(CV_CAP_PROP_FRAME_HEIGHT,480);
while(true) {
cv::Mat cameraFrame;
camera>>cameraFrame;
if (cameraFrame.empty()){
std::cerr<<"No frame read from camera"<<std::endl;
exit(1);
}
imshow("Camera",cameraFrame);
char keypress = cv::waitKey(20);
if (keypress==27) {
break;
}
}
return 0;
}
++test.pro
TEMPLATE = app
CONFIG += console
CONFIG -= app_bundle
CONFIG -= qt
SOURCES += main.cpp
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/release/ -lopencv_core
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/debug/ -lopencv_core
else:unix: LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/ -lopencv_core
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/release/ -lopencv_highgui
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/debug/ -lopencv_highgui
else:unix: LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/ -lopencv_highgui
INCLUDEPATH += $$PWD/../../../../opt/OpenCV-2.4.3/include
DEPENDPATH += $$PWD/../../../../opt/OpenCV-2.4.3/include
However, when running the program it will output Error opening camera and exit, which means the camera is not opened successfully. I have been googled a while and didn't find any possible solutions to solve this issue. Could some one give me some advice on how to solve this problem? Thanks!

Answer 1

Perhaps you are missing some addition libraries that are required for linux.
According to OpenCV install guide, Extra Prerequisites, when using OpenCV on linux, you need to install these libraries: ffmpeg, libgstreamer, libv4l, libxine, unicap, libdc1394 2.x.
On Ubuntu 12.04 , installing the following packages worked for me (*sudo apt-get install __*):
python-opencv
libhighgui2.3
libhighgui-dev
ffmpeg
libgstreamer0.10-0
libv4l-0
libv4l-dev
libxine2
libunicap2
libdc1394-22
Good Luck!