Webcam de la bibliothèque en C sous Linux?

Beaucoup d'entre nous utilisent OpenCV (croix-plate-forme de Vision par Ordinateur de la bibliothèque, actuellement sur la v2.1)

L'extrait de code suivant à l'accaparement des images de la caméra, les convertit en niveaux de gris et affiche sur l'écran:

#include <stdio.h>
#include "cv.h"
#include "highgui.h"
typedef IplImage* (*callback_prototype)(IplImage*);
/* 
* make_it_gray: custom callback to convert a colored frame to its grayscale version.
* Remember that you must deallocate the returned IplImage* yourself after calling this function.
*/
IplImage* make_it_gray(IplImage* frame)
{
//Allocate space for a new image
IplImage* gray_frame = 0;
gray_frame = cvCreateImage(cvSize(frame->width, frame->height), frame->depth, 1);
if (!gray_frame)
{
fprintf(stderr, "!!! cvCreateImage failed!\n" );
return NULL;
}
cvCvtColor(frame, gray_frame, CV_RGB2GRAY);
return gray_frame; 
}
/*
* process_video: retrieves frames from camera and executes a callback to do individual frame processing.
* Keep in mind that if your callback takes too much time to execute, you might loose a few frames from 
* the camera.
*/
void process_video(callback_prototype custom_cb)
{           
//Initialize camera
CvCapture *capture = 0;
capture = cvCaptureFromCAM(-1);
if (!capture) 
{
fprintf(stderr, "!!! Cannot open initialize webcam!\n" );
return;
}
//Create a window for the video 
cvNamedWindow("result", CV_WINDOW_AUTOSIZE);
IplImage* frame = 0;
char key = 0;
while (key != 27) //ESC
{    
frame = cvQueryFrame(capture);
if(!frame) 
{
fprintf( stderr, "!!! cvQueryFrame failed!\n" );
break;
}
//Execute callback on each frame
IplImage* processed_frame = (*custom_cb)(frame);
//Display processed frame
cvShowImage("result", processed_frame);
//Release resources
cvReleaseImage(&processed_frame);
//Exit when user press ESC
key = cvWaitKey(10);
}
//Free memory
cvDestroyWindow("result");
cvReleaseCapture(&capture);
}
int main( int argc, char **argv )
{
process_video(make_it_gray);
return 0;
}