If we don't have the same aspect ratio for the camera and the video output the result is not very pretty.
For this case, we can calculate the region we will scale. For example, if --cg is 640x480 and --vg is 480x480, we my calculate the region to be processed and set

cv::Rect crop_region(80, 0,480, 480);

and call

cv::resize(raw(crop_region), raw, cv::Size(vidGeo.value().first,vidGeo.value().second));

instead of

cv::resize(raw raw, cv::Size(vidGeo.value().first,vidGeo.value().second));

This allows to get a non distorted output.