There example on the net and code given in Learn OpenCv,Orielly.
After many attempts the out.avi file is written with 0 bytes. I wonder where i went wrong.
The following are the code i used...
int main(int argc, char* argv[]) {
CvCapture* input = cvCaptureFromFile(argv[1]);
IplImage* image = cvRetrieveFrame(input);
if (!image) {
printf("Unable to read input");
return 0;
}
CvSize imgSize;
imgSize.width = image->width;
imgSize.height = image->height;
double fps = cvGetCaptureProperty(
input,
CV_CAP_PROP_FPS
);
CvVideoWriter *writer = cvCreateVideoWriter(
"out.avi",
CV_FOURCC('M', 'J', 'P', 'G'),
fps,
imgSize
);
IplImage* colourImage;
//Keep processing frames...
for (;;) {
//Get a frame from the input video.
colourImage = cvQueryFrame(input);
cvWriteFrame(writer, colourImage);
}
cvReleaseVideoWriter(&writer);
cvReleaseCapture(&input);
}
My bet is that cvCreateVideoWriter returns NULL. Just step through it to see if it's true. In that case, the problem is probably with CV_FOURCC(..) which doesnt find the codec and force a return 0;
you can try using -1 instead of CV_FOURCC. There is gonna be a prompt during runtime for you to chose the appropriate codec