为什么我添加mp3文件后，文件的时长已经加载出来了

void MainWindow::on_btnAdd_clicked()
{
    QString curPath = QDir::homePath();
    QString dlgTitle = "选择音频文件";
    QString filter = "音频文件(*.mp3 *.wav *.wma);;mp3文件(*.mp3);;wav文件(*.wav);;wma文件(*.wma);;所有文件(*.*)";
    QStringList fileList = QFileDialog::getOpenFileNames(this, dlgTitle, curPath, filter);
    if (fileList.count() < 1)
        return;
    for (int i = 0; i < fileList.count(); i++)
    {
        QString aFile = fileList.at(i);
        QFileInfo fileInfo(aFile);
        QString fileName = fileInfo.fileName();
        QString filePath = fileInfo.absoluteFilePath();
        QString dirPath = fileInfo.absolutePath();  // 该文件所在目录的路径

    
        qDebug() << "添加音频文件：" << fileName << ", 路径：" << filePath << ", 目录：" << dirPath;

        ui.listWidget->addItem(fileName);
    }
    if (player->playbackState() != QMediaPlayer::PlayingState)
        ui.listWidget->setCurrentRow(0);
    QString url = ui.listWidget->currentItem()->text();
    qDebug() << "当前选中文件的URL：" << url;
    QDir Dir(url);
    QString Url = Dir.absolutePath();
    qDebug() << "选中文件所在目录的路径：" << Url;  
    player->setSource(QUrl::fromLocalFile(Url));
    player->play();
}
为什么我添加mp3文件后，文件的时长已经加载出来了，可就是不会播放