qmediaplayer是QT5的播放视频的一个模块。它在很多时候还是要基于第三方的解码器。这里以Ubuntu系统为例，记录其用法及进度条qslider的控制。

首先，制作一个简单的界面文件mainwindow.ui：

然后，下载一个mp4或其他格式视频（比如mkv），基于以上UI进行播放控制操作。

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow)
{timer = new QTimer();ui->setupUi(this);player = new QMediaPlayer;list = new QMediaPlaylist(player);//list->addMedia(QUrl::fromLocalFile("/home/m30.mp4"));//list->addMedia(QUrl::fromLocalFile("/home/share/2023.mkv"));list->addMedia(QUrl::fromLocalFile("/home/share/50.mp4"));list->setCurrentIndex(0);list->setPlaybackMode(QMediaPlaylist::Loop);player->setPlaylist(list);ui->widget->setAspectRatioMode(Qt::IgnoreAspectRatio);long time = player->duration();printf("duration: %lld\n", player->duration());player->setVideoOutput(ui->widget);timer->setInterval(5000);connect(timer, SIGNAL(timeout()), this, SLOT(onTimeout()));timer->start();ui->horizontalSlider->setValue(0);connect(player, &QMediaPlayer::durationChanged, ui->horizontalSlider, &QSlider::setMaximum);connect(player, &QMediaPlayer::positionChanged, ui->horizontalSlider, &QSlider::setValue);connect(ui->horizontalSlider, &QSlider::sliderMoved, this, [this](int value){printf("slide: %d\n", value);player->setPosition(value);});player->setVolume(100);player->play();//player->setPosition();
}
void MainWindow::onTimeout()
{printf("timeout\n");player->setPosition(30*1000);
}
MainWindow::~MainWindow()
{delete ui;player->stop();if (player)delete player;if(list)delete list;
}

代码集成了两种控制方式：1.定时5秒循环让进度跳到某个30秒位置；2.手动拖动进度条控制播放进度。

友好期间，顺道贴上mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <QMediaPlayer>
#include <QVideoWidget>
#include <QMediaPlaylist>
#include <QTimer>
#include <QSlider>namespace Ui {
class MainWindow;
}class MainWindow : public QMainWindow
{Q_OBJECTpublic:explicit MainWindow(QWidget *parent = 0);~MainWindow();private:Ui::MainWindow *ui;QMediaPlayer *player;QVideoWidget * videoWidget;QMediaPlaylist * list;QTimer* timer;QSlider* slid;
public slots:void onTimeout();
};#endif // MAINWINDOW_H

另外，如果遇到运行时闪退报找不到合适的解码器的错误的话，需要先安装解码器:

sudo apt install gstreamer1.0-libav -y