nvarguscamerasrc OpenCV (Solved)

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
44

works

import cv2
import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst

def read_cam():
     cap = cv2.VideoCapture("nvarguscamerasrc ! video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080,format=(string)NV12, framerate=(fraction)30/1 ! nvvidconv ! video/x-raw, format=(string)BGRx ! videoconvert ! video/x-raw, format=(string)BGR ! appsink")
     if cap.isOpened():
         cv2.namedWindow("demo", cv2.WINDOW_AUTOSIZE)
         while True:
             ret_val, img = cap.read();
             cv2.imshow('demo',img)
             if cv2.waitKey(1) == ord('q'):
                  break
     else:
         print ("camera open failed")

     cv2.destroyAllWindows()


if __name__ == '__main__':
     print(cv2.getBuildInformation())
     Gst.debug_set_active(True)
     Gst.debug_set_default_threshold(0)
     read_cam()

credits to @Honey_Patouceul code which works with the latest Jetpack 4.4 with the latest opencv 4.3.

#include <iostream>
#include <signal.h>

#include <opencv2/opencv.hpp>
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>


static cv::VideoCapture *capPtr=NULL;
void my_handler(int s){
           printf("Caught signal %d\n",s);
       if(capPtr)
        capPtr->release();
           exit(1); 
}

int main()
{
    /* Install handler for catching Ctrl-C and close camera so that Argus keeps ok */
    struct sigaction sigIntHandler;
    sigIntHandler.sa_handler = my_handler;
    sigemptyset(&sigIntHandler.sa_mask);
    sigIntHandler.sa_flags = 0;
    sigaction(SIGINT, &sigIntHandler, NULL);


    const char* gst =  "nvarguscamerasrc ! video/x-raw(memory:NVMM), width=640, height=480 !  nvvidconv ! video/x-raw,format=I420 ! appsink";
    capPtr = new cv::VideoCapture(gst, cv::CAP_GSTREAMER);
    if(!capPtr->isOpened()) {
    std::cout<<"Failed to open camera."<<std::endl;
    return (-1);
    }

    cv::namedWindow("MyCameraPreview", cv::WINDOW_AUTOSIZE);
    cv::Mat frame_in;
    while(1)
    {
        if (!capPtr->read(frame_in)) {
        std::cout<<"Capture read error"<<std::endl;
        break;
    }
    else  {
        cv::cvtColor(frame_in, frame_in, cv::COLOR_YUV2BGR_I420);
        cv::imshow("MyCameraPreview",frame_in);
        if((char)cv::waitKey(1) == (char)27)
            break;
    }    
    }

    capPtr->release();
    delete capPtr;
    return 0;
}

can be compiled e.g. with
g++ -std=c++11 -Wall -I/usr/include/opencv4/ -I/usr/local/cuda/targets/aarch64-linux/include simple_video.cpp -L/usr/lib -lopencv_core -lopencv_imgproc -lopencv_video -lopencv_videoio -lopencv_highgui -o simple_video