1 #include "opencv2/opencv.hpp"
2 #include <stdio.h>
3
4 using namespace std;
5 using namespace cv;
6
7 const int MAX_FEATURES = 500;
8 const int MAX_MOVEMENT = 100;
9
0 int move_test(Mat& oframe, Mat& frame) {
1     // Select features for optical flow
2   vector<Point2f> ofeatures;
3   goodFeaturesToTrack(oframe,
4     ofeatures, MAX_FEATURES, 0.1, 0.2 );
5
6     // Parameters for LK
7   vector<Point2f> new_features;
8   vector<uchar> status;
9   vector<float> err;
0   TermCriteria criteria(TermCriteria::COUNT
1       | TermCriteria::EPS, 20, 0.03);
2   Size window(10,10);
3   int max_level   = 3;
4   int flags       = 0;
5   double min_eigT = 0.004;
6
7     // Lucas-Kanade method
8   calcOpticalFlowPyrLK(oframe, frame,
9     ofeatures, new_features, status, err,
0     window, max_level, criteria, flags,
1     min_eigT );
2
3   double max_move = 0;
4   double movement = 0;
5   for(int i=0; i<ofeatures.size(); i++) {
6     Point pointA
7       (ofeatures[i].x, ofeatures[i].y);
8     Point pointB
9       (new_features[i].x, new_features[i].y);
0
1     movement = norm(pointA-pointB);
2     if(movement > max_move)
3         max_move = movement;
4   }
5   return max_move > MAX_MOVEMENT;
6 }
7
8 int frames_skip( VideoCapture vid, int n, int *i ) {
9     for( int c = 0; c < n; c++ ) {
0       if (!vid.grab())
1         break;
2       (*i)++;
3     }
4 }
5
6 int main(int argc, char *argv[]) {
7   int i = 0;
8   Mat frame;
9   Mat cframe;
0   Mat oframe;
1
2   if (argc != 2) {
3     cout << "USAGE: <cmd> <file_in>\n";
4     return -1;
5   }
6
7   VideoCapture vid(argv[1]);
8   if (!vid.isOpened()) {
9     cout << "Video corrupt\n";
0     return -1;
1   }
2
3   int fps = (int)vid.get(CV_CAP_PROP_FPS);
4
5   i++;
6   if(!vid.read(oframe)) return 1;
7
8   cvtColor(oframe, oframe, COLOR_BGR2GRAY);
9
0   while (1) {
1     if (!vid.read(frame))
2       break;
3     i++;
4
5     int movie_second = i / fps;
6
7     cframe = frame.clone();
8     cvtColor(frame,frame,COLOR_BGR2GRAY);
9     if(move_test(oframe, frame)) {
0       cout << movie_second << "\n";
1
2      char filename[80];
3      sprintf( filename, "%04d.jpg", i/fps );
4      imwrite( filename, cframe );
5
6       frames_skip( vid, 2*fps, &i );
7     } else {
8         // fast-forward to next 1/2 sec
9       frames_skip( vid, fps/2, &i );
0     }
1
2     oframe = frame;
3   }
4
5   return 0;
6 }