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Editorial Team
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Asked: 2026-06-17T19:56:52+00:00

I have trouble with accessing webcam using opencv 2.4.3. My System: Hp Probook 4530s

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I have trouble with accessing webcam using opencv 2.4.3.

My System:

Hp Probook 4530s – HP Fixed HD Webcam

Ubuntu 12.10

OpenCV 2.4.3

İf I want to capture my built-in camera i get ERROR: capture is NULL

I’m using http://opencv.willowgarage.com/wiki/CameraCapture sample code.

Sample code is:

#include "cv.h" 
#include "highgui.h" 
#include <stdio.h>  
// A Simple Camera Capture Framework 
int main() {
CvCapture* capture = cvCaptureFromCAM( CV_CAP_ANY );
if ( !capture ) {
 fprintf( stderr, "ERROR: capture is NULL \n" );
 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* frame = cvQueryFrame( capture );
 if ( !frame ) {
   fprintf( stderr, "ERROR: frame is null...\n" );
   getchar();
   break;
 }
 cvShowImage( "mywindow", frame );
 // 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( &capture );
cvDestroyWindow( "mywindow" );
return 0;
}

I also tried with xawtv -hwscan using typing terminal. I get this output:

looking for available devices
port 129-144

type : Xvideo, image scaler
name : Intel(R) Textured Video`


/dev/video0: OK    
             [ -device /dev/video0 ]
type : libv4l

name : HP HD Webcam [Fixed]

flags:  capture

then I can access my webcam typing xawtv video0. I think I have no trouble with my webcam.
I have trouble with opencv.

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1 Answer

  1. Editorial Team

    I solved my problem few minutes ago. And I decided share my solution for people who handling similar error.

    First I didnt install some of below packets ( I dont remember which of them, so I paste all of them)

    libjpeg62-dev

    libtiff4-dev

    zlib1g-dev

    libjasper-dev

    libavcodec-dev

    libdc1394-22-dev

    libgstreamer0.10-dev

    libgstreamer-plugins-base0.10-dev

    libavformat-dev

    libv4l-dev

    libswscale-dev

    Then You should configure your cmake process with this code

    cmake -D CMAKE_BULD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_PYTHON_SUPPORT=ON USE_V4L=ON WITH_TBB=ON -D BUILD_NEW_PYTHON_SUPPORT=ON USE_GStreamer=ON ..

    Please notice USE_V4L=ON this code..

    I hope you solve after reading my solution.

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