Example: hwdrivers_capture_video_opencv

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2024, 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;
  }
}