Camera is not recognized

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My problem is that the camera is not recognized.

I have tested Kamara with Chese and the program runs with videos. I have already googled and found nothing that fits

Sorry for my bad English

#include <opencv2/opencv.hpp>
#include <opencv2/tracking.hpp>
#include <opencv2/core/ocl.hpp>
#include <opencv2/tracking/tracker.hpp>
#include <opencv2/tracking/tldDataset.hpp>
#include <iostream>
#include <stdio.h>
using namespace cv;
using namespace std;

// Convert to string
#define SSTR( x ) static_cast< std::ostringstream & >( \
( std::ostringstream() << std::dec << x ) ).str()

int main(int argc, char **argv)
{ // List of tracker types in OpenCV 3.4.1
string trackerTypes[8] = {"BOOSTING", "MIL", "KCF", "TLD","MEDIANFLOW", "GOTURN", "MOSSE", "CSRT"};
// vector <string> trackerTypes(types, std::end(types));

// Create a tracker
string trackerType = trackerTypes[2];

Ptr<Tracker> tracker;

if (CV_MINOR_VERSION < 3)
{
    tracker = TrackerMIL::create();//        tracker = Tracker::create(trackerType);

}
else
{
    if (trackerType == "BOOSTING")
        tracker = TrackerBoosting::create();
    if (trackerType == "MIL")
        tracker = TrackerMIL::create();
    if (trackerType == "KCF")
        tracker = TrackerKCF::create();
    if (trackerType == "TLD")
        tracker = TrackerTLD::create();
    if (trackerType == "MEDIANFLOW")
        tracker = TrackerMedianFlow::create();
    if (trackerType == "GOTURN")
        tracker = TrackerGOTURN::create();
    if (trackerType == "MOSSE")
        tracker = TrackerMOSSE::create();
    if (trackerType == "CSRT")
        tracker = TrackerCSRT::create();
}


// Read video
VideoCapture video ;
video.open(-1);//video.open( "/dev/video0");

    cout << "OpenCV version : " << getBuildInformation()  << endl;
// Exit if video is not opened
if(!video.isOpened())
{
    cout << "Could not read video file" << endl; 
cout << "OpenCV version : " << CV_VERSION << endl;
    cout << "Major version : " << CV_MAJOR_VERSION << endl;
    cout << "Minor version : " << CV_MINOR_VERSION << endl;
    cout << "Subminor version : " << CV_SUBMINOR_VERSION << endl;
    return 1; 
} 

// Read first frame 
Mat frame; 
bool ok = video.read(frame); 

// Define initial bounding box 
Rect2d bbox(287, 23, 86, 320); 

// Uncomment the line below to select a different bounding box 
// bbox = selectROI(frame, false); 
// Display bounding box. 
rectangle(frame, bbox, Scalar( 255, 0, 0 ), 2, 1 ); 

imshow("Tracking", frame); 
tracker->init(frame, bbox);

while(video.read(frame))
{     
    // Start timer
    double timer = (double)getTickCount();

    // Update the tracking result
    bool ok = tracker->update(frame, bbox);

    // Calculate Frames per second (FPS)
    float fps = getTickFrequency() / ((double)getTickCount() - timer);

    if (ok)
    {
        // Tracking success : Draw the tracked object
        rectangle(frame, bbox, Scalar( 255, 0, 0 ), 2, 1 );
    }
    else
    {
        // Tracking failure detected.
        putText(frame, "Tracking failure detected", Point(100,80), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(0,0,255),2);
    }

    // Display tracker type on frame
    putText(frame, trackerType + " Tracker", Point(100,20), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(50,170,50),2);

    // Display FPS on frame
    putText(frame, "FPS : " + SSTR(int(fps)), Point(100,50), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(50,170,50), 2);

    // Display frame.
    imshow("Tracking", frame);

    // Exit if ESC pressed.
    int k = waitKey(1);
    if(k == 27)
    {
        break;
    }

}
video.release();
destroyAllWindows();
}

OpenCV version : 
General configuration for OpenCV 4.0.0-pre =====================================
  Version control:               4.0.0-beta-41-geb981cc7d

  Extra modules:
    Location (extra):            /opt/opencv_contrib/modules
    Version control (extra):     4.0.0-beta-4-gfd63e177

  Platform:
    Timestamp:                   2018-10-26T08:48:21Z
    Host:                        Linux 4.15.0-36-generic x86_64
    CMake:                       3.10.2
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/make
    Configuration:               RELEASE

  CPU/HW features:
    Baseline:                    SSE ...