QT 5.2 / OpenCV 2.4.8 - Can't open video files via VideoCapture

Zamahra

Hello Guys!

I have a big problem that i can't solve by myself. OpenCV itself works fine, but i'm not able to load videos. Here's my code:

PRO- File
@QT += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = videoredux
TEMPLATE = app

INCLUDEPATH += C:/OpenCV/opencv_bin/install/include
LIBS += -LC:\OpenCV\opencv_bin\bin
libopencv_core248d
libopencv_highgui248d
libopencv_imgproc248d
libopencv_features2d248d
libopencv_calib3d248d
libopencv_video248d \

SOURCES += main.cpp
mainwindow.cpp

HEADERS += mainwindow.h

FORMS += mainwindow.ui@

and the MainWindow Class:
@#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QFileDialog>
#include <iostream>
#include <qdebug.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv/cv.h>

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
ui->videoStatusLabel->setText("Kein Video geladen.");

// SIGNALS & SLOTS

QObject::connect(ui->chooseVideoButton,SIGNAL(clicked()),
                 this,SLOT(chooseVideo()));
QObject::connect(ui->startButton,SIGNAL(clicked()),
                 this,SLOT(startProcess()));

}

void MainWindow::chooseVideo(){

QString fileName = QFileDialog::getOpenFileName(this,
     tr("Open Video"), "/home", tr("Video Files (*.avi *.mp4 *.mpeg *.mpg)"));
qDebug() << "Path:" << fileName;
ui->videoStatusLabel->setText(fileName);

}

void MainWindow::startProcess(){
QString videoPath = ui->videoStatusLabel->text();
QFileInfo video(videoPath);
if(video.exists()){
const std::string path = videoPath.toUtf8().constData();
cv::VideoCapture capture(path);
cv::Mat frame;

    if(!capture.isOpened()){
        qDebug() << "Error, video not loaded";
    }

    cv::namedWindow("window",1);
    while(true)
    {
        bool success = capture.read(frame);
        if(success == false){
            break;
        }
        cv::imshow("window",frame);
        cv::waitKey(20);
    }
    cv::waitKey(0);
}
else{
    qDebug() << "Error, File doesn't exist";
}

}@

The paths are correct, I tried many different video formats but he never loads the videos. I'm running Qt on a Windows 8 machine and i have "K-Lite Codec Pack 10.2.0 Basic" and ffmpeg installed. The videos are playing properly with my video players. Does anyone know how to solve this problem?

Thank you very much!

Nadine

SGaist

Hi,

I would say that the path you give to OpenCV is invalid. Qt uses Unix style path internally on all platforms but not OpenCV.

Use QDir::toNativeSeparators and it should work better.