I am trying to run openCV in C and capture the camera input.

The program looks like this:

#include <iostream>
#include <sstream>
#include <new>
#include <string>
#include <sstream>

#include <opencv2/opencv.hpp>
#include <opencv2/core.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>

#define INPUT_WIDTH 3264
#define INPUT_HEIGHT 2464

#define DISPLAY_WIDTH 640
#define DISPLAY_HEIGHT 480

#define CAMERA_FRAMERATE 21/1
#define FLIP 2

void DisplayVersion()
{
    std::cout << "OpenCV version: " << cv::getVersionMajor() << "." << cv::getVersionMinor() << "." << cv::getVersionRevision() << std::endl;
}

int main(int argc, const char** argv)
{
    DisplayVersion();

    std::stringstream ss;

    ss << "nvarguscamerasrc !  video/x-raw(memory:NVMM), width=3264, height=2464, format=NV12, framerate=21/1 ! nvvidconv flip-method=2 ! video/x-raw, width=480, height=680, format=BGRx ! videoconvert ! video/x-raw, format=BGR ! appsink";

    //ss << "nvarguscamerasrc !  video/x-raw(memory:NVMM), width=" << INPUT_WIDTH <<
    //", height=" << INPUT_HEIGHT <<
    //", format=NV12, framerate=" << CAMERA_FRAMERATE <<
    //" ! nvvidconv flip-method=" << FLIP <<
    //" ! video/x-raw, width=" << DISPLAY_WIDTH <<
    //", height=" << DISPLAY_HEIGHT <<
    //", format=BGRx ! videoconvert ! video/x-raw, format=BGR ! appsink";

    cv::VideoCapture video;

    video.open(ss.str());

    if (!video.isOpened())
    {
        std::cout << "Unable to get video from the camera!" << std::endl;

        return -1;
    }

    std::cout << "Got here!" << std::endl;

    cv::Mat frame;

    while (video.read(frame))
    {
        cv::imshow("Video feed", frame);

        if (cv::waitKey(25) >= 0)
        {
            break;
        }
   }

    std::cout << "Finished!" << std::endl;

    return 0;
}

When running this code I get the following outout:

OpenCV version: 4.6.0
nvbuf_utils: Could not get EGL display connection
Error generated. /dvs/git/dirty/git-master_linux/multimedia/nvgstreamer/gst-nvarguscamera/gstnvarguscamerasrc.cpp, execute:751 Failed to create CaptureSession
[ WARN:[email protected]] global /tmp/build_opencv/opencv/modules/videoio/src/cap_gstreamer.cpp (1405) open OpenCV | GStreamer warning: Cannot query video position: status=0, value=-1, duration=-1
Got here!
Finished!

If I run the other commented command to video.open() I get this output:

OpenCV version: 4.6.0
nvbuf_utils: Could not get EGL display connection
Error generated. /dvs/git/dirty/git-master_linux/multimedia/nvgstreamer/gst-nvarguscamera/gstnvarguscamerasrc.cpp, execute:751 Failed to create CaptureSession

I'm currently running this from headless mode on a jetson nano.

I also know that OpenCV and xlaunch works because I can use mjpeg streamer from my laptop and successfully stream my laptop camera output to my jetson nano by using video.open(http://laptop-ip:laptop-port/); and that works correctly (OpenCV is able to display a live video feed using xlaunch just fine).

I think this command is telling me my camera is successfully installed:

$ v4l2-ctl -d /dev/video0 --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
        Index       : 0
        Type        : Video Capture
        Pixel Format: 'RG10'
        Name        : 10-bit Bayer RGRG/GBGB
                Size: Discrete 3264x2464
                        Interval: Discrete 0.048s (21.000 fps)
                Size: Discrete 3264x1848
                        Interval: Discrete 0.036s (28.000 fps)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.033s (30.000 fps)
                Size: Discrete 1640x1232
                        Interval: Discrete 0.033s (30.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.017s (60.000 fps)

Any help would be much appreciated

CodePudding user response：

The warning seems to be stating that you cannot use egl, ie OpenGL when in headless mode (because there is no screen)

If you run in headless mode. Would in not make more sense to not try to open a window do display?

        cv::imshow("Video feed", frame);

        if (cv::waitKey(25) >= 0)
        {
            break;
        }

Remove this code and instead use cv::imwrite to write to a file, or whatever you want to do with the data.

Or if you run ssh. Run ssh with -X option to show the windows on your client computer instead. Could be slow, but if you really want to use cv::imshow it could be a option.

CodePudding user response：

Well I fixed it by rebooting. I already did do a reboot but I also now have some errors whenever I run the program. I did recompile the dlib library but so I do think that when you update the gstreamer library you need to reboot your machine to successfully use it.