QMediaPlayer - Playing BGM Continuously in Qt - qt

Question

I am new to Qt. I want to make a game with many different screens (e.g. Main Screen, Loading Screen...), but in a single window, switched by index in a QstackWidget. When switching to the Main Screen, it should play a background music continuously. Searching the web, I found QMediaPlayer with QMediaPlayerlist can do the trick. So I tried like this (using a basic QMainWindow to simplify the code):
QtWidgetApplication1.h
#pragma once
#include <QtWidgets/QMainWindow>
#include <QMediaPlayer>
#include <QMediaPlaylist>
class QtWidgetsApplication1 : public QMainWindow
{
Q_OBJECT
public:
QtWidgetsApplication1(QWidget *parent = Q_NULLPTR);
void playAudio();
void stopAudio();
private:
QMediaPlayer* player;
QMediaPlaylist* playList;
};
QtWidgetApplication1.cpp
#include "QtWidgetsApplication1.h"
QtWidgetsApplication1::QtWidgetsApplication1(QWidget* parent)
: QMainWindow(parent)
{
playAudio();
}
void QtWidgetsApplication1::playAudio() {
player = new QMediaPlayer();
playList = new QMediaPlaylist();
playList->addMedia(QUrl::fromLocalFile("main_theme.mp3"));
playList->setPlaybackMode(QMediaPlaylist::CurrentItemInLoop);
player->setPlaylist(playList);
player->play();
}
void QtWidgetsApplication1::stopAudio() {
player->stop();
delete player;
delete playList;
player = Q_NULLPTR;
playList = Q_NULLPTR;
}
main.cpp
#include "QtWidgetsApplication1.h"
#include <QtWidgets/QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QtWidgetsApplication1 w;
w.show();
return a.exec();
}
Error:
It only plays the audio once, and shows an error message
QObject::startTimer: Timers can only be used with threads started with
QThread
Note:
I've tried (1.) using QMediaPlayer only and detecting QMediaPlayer::endOfMedia signal, (2.) QSound with a .wav file. First approach cannot get QMediaPlayer::endOfMedia signal but get QMediaPlayer::pauseState signal, however, I still fail to replay the audio. Second approach doesn't even play the audio and shows a QEventLoop error.
Enviroment:
Windows 10
Qt 5.15.2 MSVC2019 X64
Visual Studio 2019

Answer 1

Instead of adding QT += multimedia in the .pro file, which the projects in VS doesn't have, I tried to include those .lib to the project settings (Refer to How to add Qt libraries to visual studio). Actually, the best way to include QtMultiMedia is: go to
Extensions (in VS) > Qt VS tools > Qt Project Settings > General > Qt Modules and select the modules you want to include. By including the right modules, the problem I have faced has gone.