Example: hwdrivers_capture_video_ffmpeg

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/CDisplayWindow3D.h>
#include <mrpt/hwdrivers/CFFMPEG_InputStream.h>
#include <mrpt/system/CTicTac.h>
#include <mrpt/system/os.h>  // pause()

#include <iostream>
#include <thread>

using namespace mrpt::gui;
using namespace mrpt::hwdrivers;
using namespace mrpt::system;
using namespace mrpt::img;
using namespace std;

// ------------------------------------------------------
//                  Test_FFMPEG_CaptureCamera
// ------------------------------------------------------
void Test_FFMPEG_CaptureCamera(const std::string& video_url)
{
    CFFMPEG_InputStream in_video;

    if (!in_video.openURL(
            video_url, false /*grayscale*/, true /* verbose */,
            {{"rtsp_transport", "tcp"}}))
        return;

    CDisplayWindow3D win("Video");

    CTicTac tictac;
    tictac.Tic();
    unsigned int nFrames = 0;

    std::cout << "Close the window to end program.\n";

    CImage img;
    for (;;)
    {
        if (!win.isOpen())
        {
            std::cout << "Window closed. Quitting.\n";
            break;
        }
        if (!in_video.retrieveFrame(img))
        {
            std::cout << "Video stream ended. Quitting.\n";
            break;
        }

        double fps = ++nFrames / tictac.Tac();

        // decimate for easier viewing:
        while (img.getWidth() > 1024)
            img = img.scaleHalf(mrpt::img::IMG_INTERP_LINEAR);

        img.textOut(
            5, 5, mrpt::format("%.02f fps", fps), TColor(0x80, 0x80, 0x80));
        if (nFrames > 100)
        {
            tictac.Tic();
            nFrames = 0;
        }

        if (nFrames == 1)
            cout << "Video FPS: " << in_video.getVideoFPS() << endl;

        {
            auto& scene = win.get3DSceneAndLock();
            scene->getViewport()->setImageView(std::move(img));
            win.unlockAccess3DScene();
            win.repaint();
        }
        std::this_thread::sleep_for(1ms);
    }

    in_video.close();
    mrpt::system::pause();
}

int main(int argc, char** argv)
{
    try
    {
        if (argc != 2)
        {
            cout << "Usage: " << endl;
            cout << " Open a video file: " << argv[0] << " <VIDEOFILE>" << endl;
            cout << " Open an IP camera: " << argv[0]
                 << " rtsp://a.b.c.d/live.sdp" << endl;
            cout << endl;
            return 1;
        }

        Test_FFMPEG_CaptureCamera(argv[1]);

        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;
    }
}