简介

使用QT的QMediaPlayer类播放MP4格式的视频。

代码示例

头文件

Ui::MainWindow *ui;
QMediaPlaylist *playlist;
QMediaPlayer *player;
QVideoWidget *videoWidget;

方式一

应用窗体外播放视频。

.cpp文件

 playlist = new QMediaPlaylist;
 playlist->addMedia(QUrl("qrc:/video/sample5s.mp4"));
 playlist->addMedia(QUrl("qrc:/video/SampleVideo1mb.mp4"));
 playlist->setCurrentIndex(0);

 player = new QMediaPlayer;
 player->setPlaylist(playlist);

 videoWidget = new QVideoWidget;
 videoWidget->setFixedSize(1366,768); //设置video窗体大小
 videoWidget->setWindowFlag(Qt::FramelessWindowHint); //设置无边框
 player->setVideoOutput(videoWidget);
 videoWidget->show();

 player->play();

效果如下

在这里插入图片描述

方式二

UI设计器界面拖拽一个Widget，右键提升为QVideoWidget，窗体内播放视频；

.cpp文件

player = new QMediaPlayer;
playlist = new QMediaPlaylist(player);

playlist->addMedia(QUrl("qrc:/video/sample5s.mp4"));
playlist->addMedia(QUrl("qrc:/video/SampleVideo1mb.mp4"));
playlist->setCurrentIndex(0);
playlist->setPlaybackMode(QMediaPlaylist::Loop);//循环播放
player->setPlaylist(playlist);

ui->videowidget->setAspectRatioMode(Qt::IgnoreAspectRatio);//自适应铺满界面
//ui->videowidget->setFullScreen(true);  //全屏
player->setVideoOutput(ui->videowidget);
player->play();

效果如下**

在这里插入图片描述

QMediaPlayer播放视频常见信号处理

常用信号及其绑定

//播放进度
connect(player,&QMediaPlayer::positionChanged,this,&MainWindow::updatePosition);

//媒体状态
connect(player, &QMediaPlayer::mediaStatusChanged, this, &MainWindow::mediaStatusChanged);

//播放错误状态捕获
connect(player, static_cast<void(QMediaPlayer::*)(QMediaPlayer::Error)>
        (&QMediaPlayer::error), this, &MainWindow::showError);

//播放状态
connect(player, &QMediaPlayer::stateChanged, this, &MainWindow::stateChanged);

//获取元数据
connect(player, &QMediaPlayer::metaDataAvailableChanged,
           this, &MainWindow::metaDataAvailableChanged);

对应槽函数处理方法

//position 为当前播放时长，不播放则为0
//player->duration() 为视频的总时长，但当视频还没有加载完成时返回为0
void MainWindow::updatePosition(qint64 position)
{
    if(position > 0)
    {
        ui->videowidget->setVisible(true);
    }

    //不使用QMediaPlaylist时，实现循环播放
    if(position == player->duration())
    {
        if(player->duration() != 0)
        {
            player->play();
        }
    }
}

void MainWindow::mediaStatusChanged(QMediaPlayer::MediaStatus status)
{
    switch (status) {
    case QMediaPlayer::UnknownMediaStatus:
        ui->label->setText(tr("媒体未知状况！"));
        break;
    case QMediaPlayer::NoMedia:
        ui->label->setText(tr("没有媒体文件！"));
        break;
    case QMediaPlayer::BufferingMedia:
        ui->label->setText(tr("正在缓冲媒体文件！"));
        break;
    case QMediaPlayer::BufferedMedia:
        ui->label->setText(tr("媒体文件缓冲完成！"));
        break;
    case QMediaPlayer::LoadingMedia:
        ui->label->setText(tr("正在加载媒体！"));
        break;
    case QMediaPlayer::StalledMedia:
        ui->label->setText(tr("播放停滞！"));
        break;
    case QMediaPlayer::EndOfMedia:
        ui->label->setText(tr("播放结束！"));
        break;
    case QMediaPlayer::LoadedMedia:
        ui->label->setText(tr("媒体加载完成！"));
        break;
    case QMediaPlayer::InvalidMedia:
        ui->label->setText(tr("不可用的媒体文件！"));
        break;
    default: break;
    }
}

void MainWindow::stateChanged(QMediaPlayer::State state)
{
    switch (state) {
    case QMediaPlayer::StoppedState:
        ui->label_2->setText(tr("停止状态！"));
        break;
    case QMediaPlayer::PlayingState:
        ui->label_2->setText(tr("播放状态！"));
        break;
    case QMediaPlayer::PausedState:
        ui->label_2->setText(tr("暂停状态！"));
        break;
    default: break;
    }
}

void MainWindow::showError(QMediaPlayer::Error error)
{
    switch (error) {
    case QMediaPlayer::NoError:
        ui->label_3->setText(tr("没有错误！"));
        break;
    case QMediaPlayer::ResourceError:
        ui->label_3->setText(tr("媒体资源无法被解析！"));
        break;
    case QMediaPlayer::FormatError:
        ui->label_3->setText(tr("不支持该媒体格式！"));
        break;
    case QMediaPlayer::NetworkError:
        ui->label_3->setText(tr("发生了一个网络错误！"));
        break;
    case QMediaPlayer::AccessDeniedError:
        ui->label_3->setText(tr("没有播放权限！"));
        break;
    case QMediaPlayer::ServiceMissingError:
        ui->label_3->setText(tr("没有发现有效的播放服务！"));
        break;
    default:
        ui->label_3->setText(tr("未知错误码！"));
        break;
    }
}

// 获取元数据
void MainWindow::metaDataAvailableChanged(bool available)
{
    if(available)
    {
        QString title = player->metaData("Title").toString();
        QString author = player->metaData("Author").toString();
        setWindowTitle(title + "-" + author);
    }
}