OpenCV compiling issues

Question

With compiling this project I have several issues:

---

1. Due to "file not found" I had to change header from:

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

to:

#include <opencv.hpp>
#include <highgui.hpp>

that solved Include issues but compiling give several more faults:

What I'm doing wrong? Below whole code:

#include <stdio.h>
#include <unistd.h>
#include <opencv.hpp>
#include <highgui.hpp>

int main(int argc, char **argv)
{
    // get command line parameters
    if(argc < 6)
    {
        printf("Usage: %s <video> <vga window x> <vga window y> <vga width> <vga height>\n", argv[0]);
        printf("Usage: %s <camera id> <vga window x> <vga window y> <vga width> <vga height>\n", argv[0]);
        exit(0);
    }
    const char *filename = argv[1];
    int vgaX = atoi(argv[2]);
    int vgaY = atoi(argv[3]);
    int vgaWidth = atoi(argv[4]);
    int vgaHeight = atoi(argv[5]);
    int outputPixelCount = vgaWidth * vgaHeight;

    // opencv initializations
    CvCapture* cap = cvCaptureFromFile(filename);
    int isVideoFile = cap != 0;
    if (!cap)
        cap = cvCaptureFromCAM(atoi(filename));
    if (!cap)
    {
        printf("Could not open file/camera!\n");
        exit(1);
    }
    IplImage* frame = cvQueryFrame(cap); // get first frame for size
    if (!frame)
    {
        printf("The Video is empty!\n");
        cvReleaseCapture(&cap);
        exit(1);
    }
    IplImage* edges = cvCreateImage(cvGetSize(frame), IPL_DEPTH_8U, 1);
    IplImage* lines = cvCreateImage(cvGetSize(frame), IPL_DEPTH_8U, 3);
    IplImage* out = cvCreateImage(cvSize(vgaWidth, vgaHeight), IPL_DEPTH_8U, 3);
    int outStep = out->widthStep;
    int outChannels = out->nChannels;
    unsigned char *outData = (unsigned char*)out->imageData;

    // position windows // TODO: make debug output windows optional?
    cvNamedWindow("frame", CV_WINDOW_AUTOSIZE);
    cvMoveWindow("frame", 0, 32);
    cvNamedWindow("edges", CV_WINDOW_AUTOSIZE);
    cvMoveWindow("edges", frame->width, 32);
    cvNamedWindow("lines", CV_WINDOW_AUTOSIZE);
    cvMoveWindow("lines", 2 * frame->width, 32);
    cvNamedWindow("out", CV_WINDOW_AUTOSIZE);
    cvMoveWindow("out", vgaX, vgaY);

    while (42)
    {
        frame = cvQueryFrame(cap);
        if (!frame || (cvWaitKey(1) & 0xff) == 'q')
            break;
        cvShowImage("frame", frame);

        // edge detection
        cvCanny(frame, edges, 128.0, 130.0, 3); // TODO: tweakable parameters?
        cvShowImage("edges", edges);

        // get contours
        CvMemStorage *storage = cvCreateMemStorage(0);
        CvSeq *contours;
        int contourCount = cvFindContours(
            edges, storage, &contours, sizeof(CvContour),
            CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE, cvPoint(0, 0));
        cvZero(lines);
        cvDrawContours(lines, contours, cvScalar(32, 255, 32, 255), cvScalarAll(0), 100, 1, 8, cvPoint(0, 0));
        cvShowImage("lines", lines);

        // calculate total length over all contours
        float contourLengthSum = 0.0f;
        for(CvSeq *c = contours; c; c = c->h_next)
        {
            for(int i = 0; i < c->total - 1; i++)
            {
                CvPoint *p0 = CV_GET_SEQ_ELEM(CvPoint, c, i);
                CvPoint *p1 = CV_GET_SEQ_ELEM(CvPoint, c, i + 1);
                int dx = p1->x - p0->x;
                int dy = p1->y - p0->y;
                contourLengthSum += sqrtf(dx * dx + dy * dy);
            }
        }
        float factor = (float)outputPixelCount / contourLengthSum;

        // write output image
        int cx = 0, cy = 0;
        float xScale = 255.0f / frame->width;
        float yScale = 255.0f / frame->height;
        unsigned char *dp = &outData[1];
        for(CvSeq *c = contours; c; c = c->h_next)
        {
            CvPoint *p0 = CV_GET_SEQ_ELEM(CvPoint, c, 0);
            for(int i = 1; i < c->total; i++)
            {
                CvPoint *p1 = CV_GET_SEQ_ELEM(CvPoint, c, i);
                float x0x1 = p1->x - p0->x;
                float y0y1 = p1->y - p0->y;
                int n = (int)(sqrtf(x0x1 * x0x1 + y0y1 * y0y1) * factor);
                float x =          (float)p0->x * xScale;
                float y = 255.0f - (float)p0->y * yScale;
                float dt = 1.0f / (float)(n - 1);
                float dx = dt *  x0x1 * xScale;
                float dy = dt * -y0y1 * yScale;
                for (int j = 0; j < n; j++)
                {
                    dp[0] = (unsigned char)x;
                    dp[1] = (unsigned char)y;
                    x += dx;
                    y += dy;
                    dp += outChannels;
                    if (++cx == vgaWidth)
                    {
                        cx = 0;
                        dp = &outData[++cy * outStep + 1];
                        if (cy == vgaHeight)
                            goto full;
                    }
                }
                p0 = p1;
            }
        }

        // fill last few pixels with last pixel value, if there are any left
        for (; cy < vgaHeight; cy++)
        {
            for (;cx < vgaWidth; cx++)
            {
                outData[cy * outStep + cx * outChannels + 1] = 0;
                outData[cy * outStep + cx * outChannels + 2] = 0;
            }
            cx = 0;
        }

        full:
        cvReleaseMemStorage(&storage);
        cvShowImage("out", out);

        //if (isVideoFile)
        //  usleep(8000); // TODO: proper synchronization
    }
    cvReleaseImage(&out);
    cvReleaseImage(&lines);
    cvReleaseImage(&edges);
    cvReleaseCapture(&cap);
    return 0;
}

Answer 1

Looks like you are using old OpenCV API. They are replaced with new methods. Your code does not work with recent OpenCV 4.3.0. cvCaptureFromFile, cvCaptureFromCAM and some others exists in 4.0.0-rc of OpenCV docs.

https://docs.opencv.org/4.0.0-rc/dd/d01/group__videoio__c.html

After 4.0.0-rc of OpenCV the documentation points to videoio.

https://docs.opencv.org/master/dd/de7/group__videoio.html

Further Reference:

https://answers.opencv.org/question/55344/undeclared-indentifier-opencv-cvcapturefromcam-and-cvqueryframe/

Also if you have include problems in new OpenCV version try,

#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>