Qt5: how to design a translucent GUI using an image file

designed a translucent background image on GIMP, loaded the png file on qresource and using some Qt attributes was able to make the original window transparent,
the output result looks like this

//main.cpp
#include "dialog.h"

#include <QApplication>

int main(int argc, char *argv[])

{

    QApplication a(argc, argv);

    Dialog w;

    w.show();

    return a.exec();

}

//dialog.h
#ifndef DIALOG_H

#define DIALOG_H

#include <QDialog>

#include <QMediaPlayer>

#include <QPainter>

namespace Ui {

class Dialog;

}

class Dialog : public QDialog

{

    Q_OBJECT

public:

    explicit Dialog(QWidget *parent = 0);

    ~Dialog();

protected:

    void paintEvent(QPaintEvent *);

private:

    Ui::Dialog *ui;

    QMediaPlayer *player;

};

#endif // DIALOG_H

//dialog.cpp
#include "dialog.h"

#include "ui_dialog.h"

Dialog::Dialog(QWidget *parent) :

    QDialog(parent, Qt::FramelessWindowHint),

    ui(new Ui::Dialog)

{

    ui->setupUi(this);

    setAttribute(Qt::WA_TranslucentBackground);

    player = new QMediaPlayer(this);

    player->setMedia(QUrl::fromLocalFile("joke.flv"));

    player->setVolume(50);

    player->play();

}

Dialog::~Dialog()

{

    delete ui;

}

void Dialog::paintEvent(QPaintEvent *)

{

    QPainter painter(this);

    painter.drawImage(QRectF(0, 0, 400, 400), QImage(":/img.png"));

}

//player.pro

QT       += core gui multimedia
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = player
TEMPLATE = app
SOURCES += main.cpp\
        dialog.cpp
HEADERS  += dialog.h
FORMS    += dialog.ui
RESOURCES += \
    images.qrc