Filip Rooms

Camera related

For a firewire camera to work on linux, make sure that both /dev/video1394 and /dev/raw1394 are writable for the system!!
Coriander is a very nice tool to configure firewire cameras under linux.
OpenCV camera capturing and machine vision library (official docs); another API reference and yet another one.
Unicap / UCIL provides a uniform interface to video capture devices. More capturing possibilities than openCV.

OpenCV

When using a live videostream in a Qt application, make sure that you allow events of the GUI to be processed that happened during repainting the video in the GUI by adding
```
qApp->processEvents()
```
When using
```
cvShowImage()
```
in a computation loop, also add
```
cvWaitKey()
```
to allow the window to update the changed content.

From OpenCV. Let's save this code as SimpleCapture.cpp

#include "cv.h"
#include "highgui.h"
#include <iostream>
#include <cstdio>

using namespace std;

// A Simple Camera Capture Framework
int main()
{
  CvCapture* pCapture = cvCaptureFromCAM( CV_CAP_ANY );
  if( !pCapture ) 
  {
    cerr << "ERROR: capture is NULL!!" << endl << flush;
    getchar();
    return -1;
  }

  // Create a window in which the captured images will be presented
  cvNamedWindow( "mywindow", CV_WINDOW_AUTOSIZE );

  // Show the image captured from the camera in the window and repeat
  while( 1 ) 
  {
    // Get one frame
    IplImage* pFrame = cvQueryFrame( pCapture );
    if( !pFrame )
    {
      cerr << "ERROR: frame is null..." << endl << flush;
      getchar();
      break;
    }

    cvShowImage( "mywindow", pFrame );
    // Do not release the frame!

    //If ESC key pressed, Key=0x10001B under OpenCV 0.9.7(linux version),
    //remove higher bits using AND operator
    if( (cvWaitKey(10) & 255) == 27 ) break;
  }

  // Release the capture device housekeeping
  cvReleaseCapture( &pCapture );
  cvDestroyWindow( "mywindow" );
  return 0;
}

Compile under linux with:

g++ SimpleCapture.cpp -lcv -lhighgui -I/usr/include/opencv -o SimpleCapture