Example: hwdrivers_capture_video_opencv

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2021, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include <mrpt/gui/CDisplayWindow.h>
#include <mrpt/hwdrivers/CImageGrabber_OpenCV.h>
#include <mrpt/io/CFileGZOutputStream.h>
#include <mrpt/serialization/CArchive.h>
#include <mrpt/system/CTicTac.h>

#include <iostream>

using namespace mrpt::hwdrivers;
using namespace mrpt::gui;
using namespace mrpt::obs;
using namespace mrpt::system;
using namespace mrpt::io;
using namespace mrpt::serialization;
using namespace std;

// ------------------------------------------------------
//              TestCaptureOpenCV
// ------------------------------------------------------
bool LIVE_CAM = true;
int N_CAM_TO_OPEN = 0;
std::string AVI_TO_OPEN;

void TestCapture_OpenCV()
{
    CImageGrabber_OpenCV* capture = nullptr;

    if (LIVE_CAM)
    {
#if 0  // test: Select the desired resolution
        mrpt::vision::TCaptureCVOptions opts;
        opts.frame_width = 320;
        opts.frame_height = 240;
        capture = new CImageGrabber_OpenCV( 0, CAMERA_CV_AUTODETECT, opts );
#else
        capture = new CImageGrabber_OpenCV(N_CAM_TO_OPEN, CAMERA_CV_AUTODETECT);
#endif
    }
    else
    {
        capture = new CImageGrabber_OpenCV(AVI_TO_OPEN);
    }

    CTicTac tictac;

    cout << "Press any key to stop capture to 'capture.rawlog'..." << endl;

    CFileGZOutputStream fil("./capture.rawlog");

    CDisplayWindow win("Capturing...");

    int cnt = 0;

    while (!mrpt::system::os::kbhit())
    {
        if ((cnt++ % 20) == 0)
        {
            if (cnt > 0)
            {
                double t = tictac.Tac();
                double FPS = 20 / t;
                printf("\n %f FPS\n", FPS);
            }
            tictac.Tic();
        }

        CObservationImage::Ptr obs =
            CObservationImage::Create();  // Memory will be
        // freed by
        // SF destructor in each
        // loop.
        if (!capture->getObservation(*obs))
        {
            cerr << "Error retrieving images!" << endl;
            break;
        }

        archiveFrom(fil) << obs;

        cout << ".";
        cout.flush();
        if (win.isOpen()) win.showImage(obs->image);
    }

    delete capture;
}

int main(int argc, char** argv)
{
    try
    {
        if (argc > 1)
        {
            if (!strstr(argv[1], ".avi"))
            {
                LIVE_CAM = true;
                N_CAM_TO_OPEN = atoi(argv[1]);
            }
            else
            {
                LIVE_CAM = false;
                AVI_TO_OPEN = argv[1];
            }
        }

        TestCapture_OpenCV();

        return 0;
    }
    catch (const std::exception& e)
    {
        std::cerr << "MRPT error: " << mrpt::exception_to_str(e) << std::endl;
        return -1;
    }
    catch (...)
    {
        printf("Another exception!!");
        return -1;
    }
}