I'm trying to capture the video stream off of my Logitech C920 in OpenCV. With Labview I can access an MJPG stream at 30fps 1080p. In opencv I am limited to either 5fps or 640x480.
Here is the code relevant to the camera settings:
this->camRef.set(CV_CAP_PROP_FRAME_WIDTH, 1920);
this->camRef.set(CV_CAP_PROP_FRAME_HEIGHT, 1080);
this->camRef.set(CV_CAP_PROP_FOURCC,CV_FOURCC('M','J','P','G'));
These all return 1, yet I get a 5fps stream of 1080p which corresponds to the YUY2 stream.
If I add the following line:
this->camRef.set(CV_CAP_PROP_FPS, 30);
This returns 0. I get a 30 fps stream at 640x480. To me it looks like the MJPG setting isn't be accepted but I don't know what to do or how to fix that.
EDIT: The following crashes the program.
this->camRef.read(this->image);
std::cout<< this->camRef.get(CV_CAP_PROP_FOURCC) << std::endl;
std::cout<< this->camRef.set(CV_CAP_PROP_FRAME_WIDTH, config.width) << std::endl;
std::cout<< this->camRef.set(CV_CAP_PROP_FRAME_HEIGHT, config.height) << std::endl;
std::cout<< this->camRef.set(CV_CAP_PROP_FOURCC,CV_FOURCC('M','J','P','G')) << std::endl;
std::cout<< this->camRef.get(CV_CAP_PROP_FOURCC) << std::endl;
Then in my run code I have the following:
void camera::run()
{
while(true)
{
if(this->camRef.read(this->image) == 0)
{
if(this->capture)
{
cv::imwrite(fileName,this->image);
this->count++;
}
}
msleep(15);
}
}
EDIT2: Solution is to set the fourCC codec before setting camera height and width.
As the author of the post already found the solution but didn't add it as an answer I will put the solution here.
You have to set the codec before you set the wanted resolution:
working with logitech c922, needed:
Try to get first frame from capture before setting anything:
and check whether it will work without setting MJPG. If it will work, try with MJPG.
For me it's a bit weird that you have to get first frame before setting anything, but it's the only way it's working for me (windows 7 32bit).
//edit:
Yo may try to use different API - see second part of my answer here: https://stackoverflow.com/a/14188280/1598485 OpenCV is trying to use the best API by default, but maybe in your case some other API will work better.