Question

im detecting coloured balls in a video feed using opencv. i am recording the circles centre points. when the white ball moves i would like to do a detection for 10 seconds while displaying the video feed. after the 10 seconds i would like the next piece of code to run. im having trouble with this. code follows

while(1) 
{
    img = cvQueryFrame( capture );

    CvSeq* circles = cvHoughCircles(gray, storage, CV_HOUGH_GRADIENT, 1, 7, 45, 40,0,25);

    float* p;
    CvScalar s,t;
    int num_red = 15;


    for (int i = 0; i < circles->total; i++)
    {
         // round the floats to an int
         p = (float*)cvGetSeqElem(circles, i);
         cv::Point center(cvRound(p[0]), cvRound(p[1]));
         int radius = cvRound(p[2]);

         //uchar* ptr;
         //ptr = cvPtr2D(img, center.y, center.x, NULL);
         //printf("B: %d G: %d R: %d\n", ptr[0],ptr[1],ptr[2]);


         s = cvGet2D(img,center.y-6, center.x);
         t = cvGet2D(img,center.y, center.x);//colour of circle
        printf("\nB: %f G: %f R: %f\n",s.val[0],s.val[1],s.val[2]);

        if (s.val[2]<50 && s.val[1]<50 && s.val[0] <50)
        {
            printf("Black Ball\n");

        }
        else if(s.val[2]>200 && s.val[1]>200 && s.val[0]>200)
        {
            printf("White Ball\n"); 
            xpos=center.x;
            ypos=center.y;
        }
        else if(s.val[2]>=250 && s.val[1]>=250 && s.val[0] <200)
            printf("Yellow Ball\n");
        else if(s.val[2]<70 && s.val[1]>80 && s.val[0] <70)
            printf("Green Ball\n");
        else if(s.val[2]>100 && s.val[1]<100 && s.val[0] <100)
            printf("Brown Ball\n");
        else if(s.val[2]<100 && s.val[1]<100 && s.val[0] >100)
            printf("Blue Ball\n");
        else if(s.val[2]>=250 && s.val[1]<250 && s.val[0] >=250)
            printf("Pink Ball\n");
        else if (s.val[2]<=255 && s.val[2]>=0 && s.val[1]<=255 && s.val[1]>=0 && s.val[0] <=255 && s.val[0]>=0)
        {
            printf("Red Ball\n");
            //num_red++;
        }

         // draw the circle center
         cvCircle(img, center, 3, CV_RGB(0,255,0), -1, 8, 0 );

         // draw the circle outline
         cvCircle(img, center, radius+1, CV_RGB(0,0,255), 2, 8, 0 );

         //display coordinates
         printf("x: %d y: %d r: %d\n",center.x,center.y, radius);
    }

    printf("\nDetected %d balls\n", circles->total);

    if (xpos >= oldx + 10 || xpos<= oldx - 10 //wait for white ball movement here.
        && ypos >= oldy + 10 || ypos<= oldy - 10)
    {
        oldx = xpos;
        oldy = ypos;
        printf("White Ball Moving");

        //start 10second counter where balls are tracked and video displayed
        //after 10 seconds next code runs 
    }

    {
        //code to be run after 10 seconds counter but ony then
    }

}//end of while there is frame incoming

cvShowImage( "Vid", img );

Answer 1

Tip: if you are going to share code, make sure it works. The idea is to always share a minimal example that reproduces the problem you are facing. This makes it easier for us to help you.

Since your code is incomplete I had to fill the missing pieces.

The code below retrieves frames from the camera, but I imagine your original code was reading from a video file. Anyway, the program below starts a 2nd thread (using pthreads) when a white ball is detected. It writes “White Ball detected” for 10 seconds and when the timer is done it writes “10sec passed”.

Due to the lack of information, the timer will only be fired once during the lifetime of the application (after the the FIRST white ball is detected). I tried to make this procedure as simple as possible so you can change it if you want it.

#include <stdio.h>
#include "cv.h"
#include "highgui.h"

// global variable manipulated by the 2nd thread
bool wait10sec = false;

void* timer_thread(void* arg)
{
    wait10sec = true;
    sleep(10);
    wait10sec = false;
}

int main(int argc, char** argv)
{
    CvCapture *capture = 0;
    capture = cvCaptureFromCAM(-1);
    if (!capture)
    {
      fprintf(stderr, "!!! Cannot initialize webcam!\n" );
      return -1;
    }

    cvNamedWindow("result", CV_WINDOW_AUTOSIZE);

    IplImage* img = NULL;
    IplImage* gray = NULL;
    CvMemStorage* storage = cvCreateMemStorage(0);

    int xpos = 0;
    int ypos = 0;
    int oldy = 0;
    int oldx = 0;

    // Variables used to control the timer
    bool white_ball_moved = false;
    pthread_t thread_id;

    // Variables used to write text over the image
    CvFont font;
    double hScale=1.0;
    double vScale=1.0;
    int    lineWidth=1;
    cvInitFont(&font,CV_FONT_HERSHEY_SIMPLEX|CV_FONT_ITALIC, hScale,vScale,0,lineWidth);

    char key = 0;
    while (key != 27) // ESC quits the application
    {
        img = cvQueryFrame(capture);
        if (!img)
        {
            fprintf(stderr, "!!! Failed to retrive frame!\n" );
            break;
        }

        cvShowImage("result", gray);

        if (!gray)
        {
            gray = cvCreateImage(cvGetSize(img), IPL_DEPTH_8U, 1);
            if (!img)
            {
                fprintf(stderr, "!!! Failed to allocate gray frame!\n" );
                break;
            }
        }

        cvCvtColor(img, gray, CV_BGR2GRAY);

        CvSeq* circles = cvHoughCircles(gray, storage, CV_HOUGH_GRADIENT, 1, 7, 45, 40,0,25);


        float* p;
        CvScalar s,t;
        int num_red = 15;


        for (int i = 0; i < circles->total; i++)
        {
            // round the floats to an int
            p = (float*)cvGetSeqElem(circles, i);
            cv::Point center(cvRound(p[0]), cvRound(p[1]));
            int radius = cvRound(p[2]);

            s = cvGet2D(img,center.y-6, center.x);
            t = cvGet2D(img,center.y, center.x);//colour of circle
            printf("\nB: %f G: %f R: %f\n",s.val[0],s.val[1],s.val[2]);

            if (s.val[2]<50 && s.val[1]<50 && s.val[0] <50)
            {
                printf("Black Ball\n");
            }
            else if(s.val[2]>200 && s.val[1]>200 && s.val[0]>200)
            {
                printf("White Ball\n");
                xpos=center.x;
                ypos=center.y;
            }
            else if(s.val[2]>=250 && s.val[1]>=250 && s.val[0] <200)
            {
                printf("Yellow Ball\n");
            }
            else if(s.val[2]<70 && s.val[1]>80 && s.val[0] <70)
            {
                printf("Green Ball\n");
            }
            else if(s.val[2]>100 && s.val[1]<100 && s.val[0] <100)
            {
                printf("Brown Ball\n");
            }
            else if(s.val[2]<100 && s.val[1]<100 && s.val[0] >100)
            {
                printf("Blue Ball\n");
            }
            else if(s.val[2]>=250 && s.val[1]<250 && s.val[0] >=250)
            {
                printf("Pink Ball\n");
            }
            else if (s.val[2]<=255 && s.val[2]>=0 && s.val[1]<=255 && s.val[1]>=0 && s.val[0] <=255 && s.val[0]>=0)
            {
                printf("Red Ball\n");
                //num_red++;
            }

            // draw the circle center
            cvCircle(img, center, 3, CV_RGB(0,255,0), -1, 8, 0 );

            // draw the circle outline
            cvCircle(img, center, radius+1, CV_RGB(0,0,255), 2, 8, 0 );

            //display coordinates
            printf("x: %d y: %d r: %d\n",center.x,center.y, radius);
        }

        printf("\nDetected %d balls\n", circles->total);

        if (white_ball_moved && wait10sec)
        {
            // white ball detected: execute this code for the next 10 seconds

            cvPutText (img, "White Ball detected", cvPoint(200,400), &font, cvScalar(255,255,0));
        }
        else if (white_ball_moved && !wait10sec)
        {
            // white ball was detected and 10 seconds have passed
            cvPutText (img, "10sec passed", cvPoint(200,400), &font, cvScalar(255,255,0));
        }

        if (!white_ball_moved)
        {
            if (xpos >= oldx + 10 || xpos<= oldx - 10 //wait for white ball movement here.
                && ypos >= oldy + 10 || ypos<= oldy - 10)
            {
                oldx = xpos;
                oldy = ypos;
                printf("White Ball Moving");

                white_ball_moved = true;

                // start 2nd thread to do the counting
                pthread_create(&thread_id, NULL, timer_thread, NULL);
            }
        }

        cvShowImage("result", img);
        key = cvWaitKey(33);
    } // end of while, no more frames will be retrieved

    pthread_join(thread_id, NULL);
    pthread_exit(NULL);

    return 0;
}

Compiled with:

g++ balls.cpp -o balls -I/usr/local/include/opencv -I/usr/local/include -L/usr/local/lib -lopencv_core -lopencv_imgproc -lopencv_highgui -lpthread

EDIT:

Windows version:

#include <process.h>
#include <stdio.h>

#include <cv.h>
#include <highgui.h>

// global variable manipulated by the 2nd thread
bool wait10sec = false;

void timer_thread(void* arg)
{
    wait10sec = true;
    Sleep(10000); // 10s
    wait10sec = false;
}

int main(int argc, char** argv)
{
    CvCapture *capture = 0;
    capture = cvCaptureFromCAM(-1);
    if (!capture)
    {
      fprintf(stderr, "!!! Cannot initialize webcam!\n" );
      return -1;
    }

    cvNamedWindow("result", CV_WINDOW_AUTOSIZE);

    IplImage* img = NULL;
    IplImage* gray = NULL;
    CvMemStorage* storage = cvCreateMemStorage(0);

    int xpos = 0;
    int ypos = 0;
    int oldy = 0;
    int oldx = 0;

    // Variables used to control the timer
    bool white_ball_moved = false;

    // Variables used to write text over the image
    CvFont font;
    double hScale=1.0;
    double vScale=1.0;
    int    lineWidth=1;
    cvInitFont(&font,CV_FONT_HERSHEY_SIMPLEX|CV_FONT_ITALIC, hScale,vScale,0,lineWidth);

    char key = 0;
    while (key != 27) // ESC quits the application
    {
        img = cvQueryFrame(capture);
        if (!img)
        {
            fprintf(stderr, "!!! Failed to retrive frame!\n" );
            break;
        }

        cvShowImage("result", gray);

        if (!gray)
        {
            gray = cvCreateImage(cvGetSize(img), IPL_DEPTH_8U, 1);
            if (!img)
            {
                fprintf(stderr, "!!! Failed to allocate gray frame!\n" );
                break;
            }
        }

        cvCvtColor(img, gray, CV_BGR2GRAY);

        CvSeq* circles = cvHoughCircles(gray, storage, CV_HOUGH_GRADIENT, 1, 7, 45, 40,0,25);


        float* p;
        CvScalar s,t;
        int num_red = 15;


        for (int i = 0; i < circles->total; i++)
        {
            // round the floats to an int
            p = (float*)cvGetSeqElem(circles, i);
            cv::Point center(cvRound(p[0]), cvRound(p[1]));
            int radius = cvRound(p[2]);

            s = cvGet2D(img,center.y-6, center.x);
            t = cvGet2D(img,center.y, center.x);//colour of circle
            printf("\nB: %f G: %f R: %f\n",s.val[0],s.val[1],s.val[2]);

            if (s.val[2]<50 && s.val[1]<50 && s.val[0] <50)
            {
                printf("Black Ball\n");
            }
            else if(s.val[2]>200 && s.val[1]>200 && s.val[0]>200)
            {
                printf("White Ball\n");
                xpos=center.x;
                ypos=center.y;
            }
            else if(s.val[2]>=250 && s.val[1]>=250 && s.val[0] <200)
            {
                printf("Yellow Ball\n");
            }
            else if(s.val[2]<70 && s.val[1]>80 && s.val[0] <70)
            {
                printf("Green Ball\n");
            }
            else if(s.val[2]>100 && s.val[1]<100 && s.val[0] <100)
            {
                printf("Brown Ball\n");
            }
            else if(s.val[2]<100 && s.val[1]<100 && s.val[0] >100)
            {
                printf("Blue Ball\n");
            }
            else if(s.val[2]>=250 && s.val[1]<250 && s.val[0] >=250)
            {
                printf("Pink Ball\n");
            }
            else if (s.val[2]<=255 && s.val[2]>=0 && s.val[1]<=255 && s.val[1]>=0 && s.val[0] <=255 && s.val[0]>=0)
            {
                printf("Red Ball\n");
                //num_red++;               
            }

            // draw the circle center
            cvCircle(img, center, 3, CV_RGB(0,255,0), -1, 8, 0 );

            // draw the circle outline
            cvCircle(img, center, radius+1, CV_RGB(0,0,255), 2, 8, 0 );

            //display coordinates
            printf("x: %d y: %d r: %d\n",center.x,center.y, radius);
        }

        printf("\nDetected %d balls\n", circles->total);

        if (white_ball_moved && wait10sec)
        {
            // white ball detected: execute this code for the next 10 seconds

            cvPutText (img, "White Ball detected", cvPoint(50,50), &font, cvScalar(255,255,0));
        }
        else if (white_ball_moved && !wait10sec)
        {
            // white ball was detected and 10 seconds have passed
            cvPutText (img, "10sec passed", cvPoint(50,50), &font, cvScalar(255,255,0));
        }

        if (!white_ball_moved)
        {
            if (xpos >= oldx + 10 || xpos<= oldx - 10 //wait for white ball movement here.
                && ypos >= oldy + 10 || ypos<= oldy - 10)
            {
                oldx = xpos;
                oldy = ypos;
                printf("White Ball Moving");

                white_ball_moved = true;

                // start 2nd thread to do the counting
                _beginthread(timer_thread, 0, NULL);
            }
        }

        cvShowImage("result", img);
        key = cvWaitKey(33);
    } // end of while, no more frames will be retrieved

    return 0;
}