OpenCV can't find my USB webcam
I am trying to create an OpenCV application on my MacBook with built-in iSight camera. I grabbed some very simple code off the internet and ran it with no trouble. OpenCV automatically discovered the built-in webcam and ran properly but I can't get it to work with my USB webcam.
#include <stdio.h>
#include <opencv.hpp>
int main( int argc, char **argv )
{
CvCapture *capture = 0;
IplImage *frame = 0;
int key = 0;
/* initialize camera */
capture = cvCaptureFromCAM(0);
/* always check */
if ( !capture ) {
fprintf( stderr, "Cannot open initialize webcam!n" );
return 1;
}
/* create a window for the video */
cvNamedWindow( "Test", CV_WINDOW_AUTOSIZE );
while( key != 'q' ) {
/* get a frame */
frame = cvQueryFrame( capture );
/* always check */
if( !frame ) break;
/* display current frame */
cvShowImage( "Test", frame );
/* exit if user press 'q' */
key = cvWaitKey( 1 );
}
/* free memory */
cvDestroyWindow( "Test" );
cvReleaseCapture( &capture );
return 0;
}
I compiled this with:
g++ webcam.c -o webcam -I/opt/local/include/opencv2 -I/opt/local/include -L/opt/local/lib -lopencv_core -lopencv_highgui
According to the documentation, by changing the line capture = cvCaptureFromCAM(0);
to capture = cvCaptureFromCAM(1);
I should be able to access the other webcam that I have plugged in but running the program gives me the error message: Warning: Max Camera Num is 0; Using camera 0
Warning: Max Camera Num is 0; Using camera 0
What steps can I take to get OpenCV to recognize that I have another camera connected to my USB drive?
This is based on windows experience, but I believe the main issue to be the same. (To get input from a logitech USB-camera on my laptop.)
As far as I recall; OpenCV does not support multiple cameras, and thereby not the choice of camera. I am guessing that you can easily run your build-in camera with the code you've shown. My solution to a similar problem was deactivating the build-in camera. Giving the USB camera the only "availavle" slot for your cvCaptureFromCAM(0) function.
I hope this can solve your problem, even though the solution is a little 'clunky'.
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