Debug Assertion Failed (unsigned)(c+1) <= 256 (in VideoCapture::open [Qt Creator])

I've been trying to use cv::VideoCapture:: open("< path to video file >") in QtCreator (opencv added). Even though the program runs without errors in "bebug mode" (debug build), it gives below runtime error in "release mode" (release build).

Quote:

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Debug Assertion Failed File: f:/dd/vctools/crt_bld/self_x86/src/isctype.c Line: 56 Expression: (unsigned)(c+1) <= 256

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It is a simple program which uses only cv::VideoCapture:: open() [for testing purposes]

Below is the .pro file

Code:

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QT       += core gui
 
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = untitled
TEMPLATE = app
SOURCES += main.cpp\
        mainwindow.cpp   
HEADERS  += mainwindow.h   
FORMS    += mainwindow.ui   
 
INCLUDEPATH += C:/C/opencv/build/include
INCLUDEPATH += C:/C/opencv/build/include/opencv  
 
LIBS += C:/C/opencv/build/x86/vc10/lib/opencv_highgui240d.lib
LIBS += C:/C/opencv/build/x86/vc10/lib/opencv_highgui240.lib
 
 
LIBS += C:/C/opencv/build/x86/vc10/bin/opencv_highgui240d.dll
LIBS += C:/C/opencv/build/x86/vc10/bin/opencv_highgui240.dll

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Below is the Header file

Code:

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#include <QMainWindow>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/core/core.hpp>
 
namespace Ui {
class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
private:
    Ui::MainWindow *ui;
    cv::VideoCapture vcap;
};

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Below is the .cpp file

Code:

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#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    vcap.open("C:/Users/ANURUDDHA/pedestrians/ThreePastShop2cor.mpg");
}
 
MainWindow::~MainWindow()
{
    delete ui;
}

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When I pass an int as the argument to cv::VideoCapture:: open() [eg: vcap.open(0)] it runs without errors in both debug and release build and opens webcam successfully. Problem comes only when I pass a String to arguments.

Someone please shed some light on this. Really appreciated.