GStreamer Pipline with OpenCV on Coral Dev Board - c++

Question

I am trying to access the CSI Camera on the Coral Dev Board via OpenCV and GStreamer in C++;
This is my pipline code that seems to work fine when testing with gst:
gst-launch-1.0 v4l2src device = /dev/video0 ! video/x-raw,format=YUY2,width=640,height=480,framerate=30/1 ! videoconvert ! video/x-raw,format=BGR ! appsink drop=1
But when trying to open it with OpenCV it doesnt seem to do the trick:
#include "opencv2/opencv.hpp"
#include <iostream>
int main() {
std::string pipline = "v4l2src device = /dev/video0 ! video/x-raw,format=YUY2,width=640,height=480,framerate=30/1 ! videoconvert ! video/x-raw,format=BGR ! appsink drop=1";
cv::VideoCapture capture(pipline, cv::CAP_GSTRAMER);
if (!_capture.isOpened()) {
std::cout << "Could not open Camera" << std::endl;
}
return 0;
}
Also, is there somehow a more detailed error message available via opencv? When running gst-launch-1.0 it tells me quite specifically what it didnt like about my pipline string. But in opencv it just seems to tell me that it didnt work.

Answer 1

OpenCv VideoCapture has 5 overloaded functions and all of them don't include this type implementation. You can use the followings as VideoCapture inputs:
video file or image file sequence
a capturing device index
IP video stream link
As I see in your command, your CSI camera locates on device = /dev/video0 so you can call it simply with the line:
cv::VideoCapture capture(0, cv::CAP_GSTREAMER);