c++ - cannot convert 'cv::VideoCapture' to 'CvCapture*' -

i have simple program takes video , plays (though image processing on video). video can retrieved dialog box result, or directly giving path of file. when use cv::cvcapture capture1, properties capture1.isopen(), capture1.get(cv_cap_prop_frame_count) etc. when use cvcapture* capture2 weird errors.

i want use cv::cvcapture capture1 because of functions in accordance capture1. or there way use both types kind of conversion between them type casting or else.

actually had 2 programs, functions of program1 cv::cvcapture , functions of program2 cvcapture*. mean 2 programs read video file in different manners.

i merged these 2 programs use functions program1 , functions program2. can't convert cv::cvcapture cvcapture*.

i using opencv qt creator.

my code long post here have simplified code make smaller , understandable. code may not compile correctly because modified make simpler.

any appreciated. in advance :)

void mainwindow::on_pushbutton_clicked() {   std::string filename = qfiledialog::getopenfilename(this,tr("open video"), ".",tr("video files (*.mp4 *.avi)")).tostdstring();  cv::videocapture  capture1(filename);       // when use cv::videocapture capture gives  error  //error: cannot convert 'cv::videocapture' 'cvcapture*' argument '1' 'iplimage* cvqueryframe(cvcapture*)     //cvcapture* capture2 = cvcapturefromcam(-1);     // when use cvcapture* capture2, not recognize capture2.isopend() , capture2.get(cv_cap_prop_frame_count) etc. don't work.     // there way convert videocapture cvcapture*?     if (!capture.isopened())         {             qmessagebox msgbox;             msgbox.exec(); // messagebox message. not important         }  cvnamedwindow( name );  iplimage* ximage = cvqueryframe(capture);  if (!ximage)    {      qmessagebox msgbox;      msgbox.exec();     }   double rate= capture.get(cv_cap_prop_fps);  int frames=(int)capture.get(cv_cap_prop_frame_count); int frameno=(int)capture.get(cv_cap_prop_pos_frames);  bool stop(false);   capture.read(imgsize);   cv::mat out(imgsize.rows,imgsize.cols,cv_8sc1);  cv::mat out2(imgsize.rows,imgsize.cols,cv_8sc1);         //i print frame numbers , total frames on  label.             ui->label_3->settext(qstring::number(frameno/1000)+" / "+qstring::number(frames/1000));              ui->label->setscaledcontents(true);              ui->label->setpixmap(qpixmap::fromimage(img1)); // here show frames on label.   } 

cv::videocapture c++ interface of opencv, , can used capture camera device , file on disk

cv::videocapture  capture1(filename);  if (!capture.isopened()) {     // failed, print error message } 

and cvcapturefromcam() function c interface of opencv used capture camera device:

cvcapture* capture2 = cvcapturefromcam(-1); if (!capture2) {     // failed, print error message } 

don't mix/merge interfaces together, pick 1 , stick it.

if want use c interface capture video file, use cvcapturefromfile() instead:

cvcapture* capture  = cvcapturefromfile(filename); if (!capture) {     // print error, quit application } 

check these examples:

• camera capture using c interface
• camera capture using c++ interface