I have a video engine2.avi that I want to read and show with openCV. Here's my code:
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
using namespace cv;
int main(int argc, char** argv)
{
string filename = "D:\\BMDvideos\\engine2.avi";
VideoCapture capture(filename);
Mat frame;
if( !capture.isOpened() )
throw "Error when reading steam_avi";
namedWindow("w", 1);
for( ; ; )
{
capture >> frame;
//if(!frame)
// break;
imshow("w", frame);
waitKey(20); // waits to display frame
}
waitKey(0);
}
This code doesn't work if my file has the codec YUV 4:2:2 (UYVY)
(I recorded the video using Direct-Show), but works when I use a video I grabbed whit openCV !!
Has anybody an Idea how this could work ?
UPDATE:
After reading some links, suggesting that catching exception will solve the problem, I modified my code. It didn't help, but here is the modified code:
cv::VideoCapture cap("d:\\BMDvideos\\engine2.avi");
cv::Mat frame;
try
{
cap >> frame;
}
catch(cv::Exception ex)
{
std::cout << ex.what() << std::endl;
}
catch(...)
{
std::cout << "Unknown exception" << std::endl;
}
The program crashes in cap>>frame
. I readed similar questions but they use a frame in YUV (4:2:0), while my video has UYVY (4:2:2). How can I convert this into RGB color model?
UPDATE 2:
After karlphillip's suggestion, I used OpenCV2.4.3, but I still got the same error using the code below:
#include <opencv2\core\core.hpp>
#include <opencv2\highgui\highgui.hpp>
#include <opencv2\opencv.hpp>
using namespace cv;
using namespace std;
int main(){
cv::Mat frame;
cv::VideoCapture cap("d:\\BMDvideos\\B\\Aufnahme.avi");
if(!cap.isOpened())
{
cout << "Error can't find the file"<<endl;
}
while(1){
if(!cap.read(frame))
imshow("",frame);
cv::waitKey(33);
}
return 0;
}
Here is a couple of links that might help you:
Edit:
I must clear something first: OpenCV is capable of reading YUV frames from a video file because it's the underlying library (FFmpeg/GStreamer) that does the job. OpenCV also supports converting between a specific type of YUV and RGB through cvCvtColor()
with CV_YCrCb2RGB
or CV_RGBYCrCb
.
Upon examining your question again, I noticed you didn't specify the kind of error that happened. You could do a better job at dealing with a possible failure from the capture interface by printing a message to the screen instead of throw
ing it.
I tested the video file you shared and I had no problems playing it on a window using the following code:
#include <cv.h>
#include <highgui.h>
#include <iostream>
int main(int argc, char* argv[])
{
cv::VideoCapture cap(argv[1]);
if (!cap.isOpened())
{
std::cout << "!!! Failed to open file: " << argv[1] << std::endl;
return -1;
}
cv::Mat frame;
for(;;)
{
if (!cap.read(frame))
break;
cv::imshow("window", frame);
char key = cvWaitKey(10);
if (key == 27) // ESC
break;
}
return 0;
}
If, for some reason, the capture interface fails to open the file it will quit the application immediately, instead of going further just to crash at cap.read(frame)
.
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