extract gif

gif_animated.cc

#include "cv.h"
#include "highgui.h"

#include <iostream>
#include <string>
using namespace std;

void help(const string& exec_name) {
    cout << exec_name << " src tgt w h" << endl;
}

int main(int argc, char ** argv)
{
    string src = "";
    string tgt = "";
    int w;
    int h;

    if (argc != 5) return 0;
    src = argv[1];
    tgt = argv[2];
    stringstream(string(argv[3])) >> w;
    stringstream(string(argv[4])) >> h;
    if (src == "" || tgt == "") {
        help(argv[0]);
        return 0;
    }
    
    auto capture = cvCreateFileCapture(src.c_str());
    auto ix = 0;
    if (capture == nullptr) return -2;
    while (true) {
        if (cvGrabFrame(capture) == 0) break;
        auto frame = cvRetrieveFrame(capture);
        if (frame == nullptr) break;

        auto outf = ostringstream();
        outf << tgt << "_" << ix << ".png";

        auto h2 = w * ((float)frame->height / frame->width);
        auto w2 = h * ((float)frame->width / frame->height);
        auto s = h2 <= h ? CvSize(w, h2) : CvSize(w2, h);

        auto o = cvCreateImage(s, frame->depth, frame->nChannels);
        cvResize(frame, o, CV_INTER_AREA);
        cvSaveImage(outf.str().c_str(), o);
        cvReleaseImage(&o);

        ix++;
    }

    cvReleaseCapture(&capture);

    return 0;
}