[ros-users] cvCaptureFromAVI returns NULL

[Dejan Pangercic]

Hi beepbeep:-),

are you using openCV from ROS? In my case I had to enable "-D
WITH_FFMPEG=ON" in pkg's Makefile and recompile.

cheers,d.

On Mon, Sep 13, 2010 at 11:24 PM, beepbeep <mvharish14988 at gmail.com> wrote:
>
> Hello,
>
> I've been trying to get the following code working. It's a standard code to
> read AVI files from here:
> http://nashruddin.com/How_to_Play_AVI_Files_with_OpenCV
>
> Eventually, I want to send this to a camera display in Rviz.
>
> #include <ros/ros.h>
> #include "sensor_msgs/Image.h"
> #include "image_transport/image_transport.h"
> #include "cv_bridge/CvBridge.h"
> #include <opencv/cv.h>
> #include <opencv/highgui.h>
>
> int main( int argc, char** argv )
> {
>          IplImage  *frame;
>          int key;
>           //assert( argc == 2 );
>          CvCapture *capture =
> cvCaptureFromAVI("/home/harish/Desktop/movie.avi");
>          printf("Hello1");
>          if( !capture )
>          {
>          printf("Hello2");
>          return 1;
>          }
>          int fps = ( int )cvGetCaptureProperty( capture, CV_CAP_PROP_FPS );
>          cvNamedWindow( "video", 0 );
>          while( key != 'q' ) {
>              frame = cvQueryFrame( capture );
>              if( !frame ) break;
>              cvShowImage( "video", frame );
>              key = cvWaitKey( 1000 / fps );
>          }
>
>          cvReleaseCapture( &capture );
>          cvDestroyWindow( "video" );
>          return 0;
>      }
>
> For some reason, cvCaptureFromAVI returns NULL, because Hello2 is printed in
> the output.
> The file movie.avi is stored in the bin folder, src folder, and package
> folder as well. I've also tried an absolute path to my Desktop.
>
> The interesting thing is that the code executes perfectly if compiled using
> g++ in the regular way, independent of ROS. But using rosmake, or just make,
> something happens, and cvCaptureFromAVI returns NULL during execution.
>
> Any ideas? According to a friend, possibly something to do with rosmake or
> the makefiles is creating trouble..
>
> Thanks.
>
>
>
>
>
>
>
> --
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-- 
MSc. Dejan Pangercic
PhD Student/Researcher
Intelligent Autonomous Systems Group
Technische Universität München
Telephone: +49 (89) 289-26908
E-Mail: dejan.pangercic at cs.tum.edu
WWW: http://ias.cs.tum.edu/people/pangercic