libVLC 设置视频宽高比

宽高比是指视频图像的宽度和高度之间的比率。

投影屏幕尺寸一般都按照对角线的大小来定义的。根据图像制式不同，屏幕的长宽比例也有几种格式：

传统影视的宽高比是 4：3，宽屏幕电影的宽高比是 1.85：1，高清晰度电视是 16：9，全景式格式电影是 2.35：1。

以下是VLC播放器中使用的宽高比，我们仿照这个宽高比例做一个界面。

使用libvlc_video_set_aspect_ratio设置视频宽高比。

首先做一个菜单：

cpp 复制代码

	//.h
    QMenu *m_menu = nullptr;
	QAction *m_default = nullptr;
	QAction *m_16_9 = nullptr;
	QAction *m_4_3 = nullptr;
	QAction *m_1_1 = nullptr;
	QAction *m_16_10 = nullptr;
	QAction *m_2_21_1 = nullptr;
	QAction *m_2_35_1= nullptr;
	QAction *m_2_38_1 = nullptr;
	QAction *m_5_4 = nullptr;

	QActionGroup *m_group = nullptr;


    //.cpp
    m_menu = new QMenu(this);
	m_default = m_menu->addAction("默认");
	m_16_9 = m_menu->addAction("16:9");
	m_4_3 = m_menu->addAction("4:3");
	m_1_1 = m_menu->addAction("1:1");
	m_16_10 = m_menu->addAction("16:10");
	m_2_21_1 = m_menu->addAction("2.21:1");
	m_2_35_1 = m_menu->addAction("2.35:1");
	m_2_38_1 = m_menu->addAction("2.38:1");
	m_5_4 = m_menu->addAction("5:4");

	m_group = new QActionGroup(this);
	m_group->addAction(m_default);
	m_group->addAction(m_16_9);
	m_group->addAction(m_4_3);
	m_group->addAction(m_1_1);
	m_group->addAction(m_16_10);
	m_group->addAction(m_2_21_1);
	m_group->addAction(m_2_35_1);
	m_group->addAction(m_2_38_1);
	m_group->addAction(m_5_4);

	connect(m_group, &QActionGroup::triggered, this, &showWidget::slotActionTriggered);

接受槽函数的响应事件：

cpp 复制代码

void showWidget::slotActionTriggered(QAction *action)
{
	if (!vlc_mediaPlayer)
		return;

	if (action == m_default)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer,m_defalutRate);
	else if(action == m_16_9)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "16:9");
	else if (action == m_4_3)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "4:3");
	else if (action == m_1_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "1:1");
	else if (action == m_16_10)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "16:10");
	else if (action == m_2_21_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "221:100");
	else if (action == m_2_35_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "235:100");
	else if (action == m_2_38_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "238:100");
	else if (action == m_5_4)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "5:4");
}

设置鼠标右键弹出菜单：重写鼠标点击事件。

cpp 复制代码

void showWidget::mousePressEvent(QMouseEvent *event)
{
	switch (event->button())
	{
	case Qt::RightButton:
		//this->setWindowState(Qt::WindowMinimized);
		m_menu->exec(event->globalPos());
		break;
	default:
		QWidget::mousePressEvent(event);
	}
}

完整代码：

cpp 复制代码

#include "showWidget.h"
#include <QTimer>
#include <QTime>

#pragma execution_character_set("utf-8")

showWidget::showWidget(QWidget *parent)
    : QWidget(parent)
{
    ui.setupUi(this);

	this->setWindowTitle("视频播放器");

	ui.cbxRate->setCurrentIndex(Rate1_0X);

	m_lstRate << 2.0 << 1.5 << 1.25 << 1.0 << 0.75 << 0.5;

	m_menu = new QMenu(this);
	m_default = m_menu->addAction("默认");
	m_16_9 = m_menu->addAction("16:9");
	m_4_3 = m_menu->addAction("4:3");
	m_1_1 = m_menu->addAction("1:1");
	m_16_10 = m_menu->addAction("16:10");
	m_2_21_1 = m_menu->addAction("2.21:1");
	m_2_35_1 = m_menu->addAction("2.35:1");
	m_2_38_1 = m_menu->addAction("2.38:1");
	m_5_4 = m_menu->addAction("5:4");

	m_group = new QActionGroup(this);
	m_group->addAction(m_default);
	m_group->addAction(m_16_9);
	m_group->addAction(m_4_3);
	m_group->addAction(m_1_1);
	m_group->addAction(m_16_10);
	m_group->addAction(m_2_21_1);
	m_group->addAction(m_2_35_1);
	m_group->addAction(m_2_38_1);
	m_group->addAction(m_5_4);

	connect(m_group, &QActionGroup::triggered, this, &showWidget::slotActionTriggered);

	connect(ui.btnOpen, &QPushButton::clicked, this, &showWidget::slotOpenFile);
	connect(ui.btnPlay, &QPushButton::clicked, this, &showWidget::slotPlay);
	connect(ui.btnPause, &QPushButton::clicked, this, &showWidget::slotPause);
	connect(ui.btnStop, &QPushButton::clicked, this, &showWidget::slotStop);
	connect(ui.hSliderVolumn, &QSlider::valueChanged, this, &showWidget::slotValueChanged);
	connect(ui.cbxRate,SIGNAL(currentIndexChanged(int)), this, SLOT(slotCurrentIndexChanged(int)));
}

showWidget::~showWidget()
{
	libvlc_release(vlc_base); //减少libvlc实例的引用计数，并销毁
}

void showWidget::mousePressEvent(QMouseEvent *event)
{
	switch (event->button())
	{
	case Qt::RightButton:
		//this->setWindowState(Qt::WindowMinimized);
		m_menu->exec(event->globalPos());
		break;
	default:
		QWidget::mousePressEvent(event);
	}
}

void showWidget::slotOpenFile()
{
	/*选择文件*/
	QString filename = QFileDialog::getOpenFileName(this, "选择打开的文件", "D:/", tr("*.*"));
	std::replace(filename.begin(), filename.end(), QChar('/'), QChar('\\'));
	vlc_base = libvlc_new(0, NULL);
	vlc_media = libvlc_media_new_path(vlc_base, filename.toUtf8().data());
	if (!vlc_media) {
		return;
	}

	// 创建libvlc实例和媒体播放器
	vlc_mediaPlayer = libvlc_media_player_new_from_media(vlc_media);
	if (!vlc_mediaPlayer) {
		return;
	}

	// 等待元数据加载完成
	libvlc_media_parse(vlc_media);

	m_defalutRate = libvlc_video_get_aspect_ratio(vlc_mediaPlayer);

	// 获取各种元数据
	const char *title = libvlc_media_get_meta(vlc_media, libvlc_meta_Title);
	const char *artist = libvlc_media_get_meta(vlc_media, libvlc_meta_Artist);
	const char *album = libvlc_media_get_meta(vlc_media, libvlc_meta_Album);
	const char *url = libvlc_media_get_meta(vlc_media, libvlc_meta_URL);
	const char *date = libvlc_media_get_meta(vlc_media, libvlc_meta_Date);
	const char *lang = libvlc_media_get_meta(vlc_media, libvlc_meta_Language);
	int duration = libvlc_media_get_duration(vlc_media);  // 获取时长（单位：毫秒）

	qDebug("Title: %s", title ? title : "N/A");
	qDebug("Artist: %s", artist ? artist : "N/A");
	qDebug("Album: %s", album ? album : "N/A");
	qDebug("Duration: %d ms", duration);
	qDebug("url: %s", url ? url : "N/A");
	qDebug("date: %s", date ? date : "N/A");
	qDebug("lang: %s", lang ? lang : "N/A");
	
	libvlc_media_track_t **tracks;
	int track_count = libvlc_media_tracks_get(vlc_media,&tracks);
	for (unsigned i = 0; i < track_count; i++) 
	{
		libvlc_media_track_t* track = tracks[i];

		// 显示轨道信息
		printf("Track #%u: %s\n", i, track->psz_description);

		// 这里可以获取到每一个轨道的信息，比如轨道类型 track->i_type
		// 可能是 libvlc_track_video, libvlc_track_audio 或者 libvlc_track_text (字幕)

		if (track->i_type == libvlc_track_video) {
			// 处理视频轨道信息
			qDebug("width = %d",track->video->i_width);
			qDebug("height = %d", track->video->i_height);
			qDebug("rate_num = %d", track->video->i_frame_rate_num);
			qDebug("rate_den = %d", track->video->i_frame_rate_den);
		}
		else if (track->i_type == libvlc_track_audio) {
			// 处理音频轨道信息
			qDebug("channels = %d", track->audio->i_channels);
			qDebug("rate = %d", track->audio->i_rate);
		}
		else if (track->i_type == libvlc_track_text) {
			// 处理字幕轨道信息
		}
	}

	 设置 logo 叠加
	//libvlc_video_set_logo_int(vlc_mediaPlayer, libvlc_logo_enable, 1);
	//libvlc_video_set_logo_string(vlc_mediaPlayer, libvlc_logo_file, "D:\\2.png");
	libvlc_video_set_logo_int(vlc_mediaPlayer, libvlc_logo_position, libvlc_position_top_left);
	//libvlc_video_set_logo_int(vlc_mediaPlayer, libvlc_logo_x, 100);
	//libvlc_video_set_logo_int(vlc_mediaPlayer, libvlc_logo_y, 0);
	//libvlc_video_set_logo_int(vlc_mediaPlayer, libvlc_logo_opacity, 255);
	//libvlc_video_set_logo_int(vlc_mediaPlayer, libvlc_logo_repeat, 1);

	 创建并设置水印文本
	//libvlc_video_set_marquee_int(vlc_mediaPlayer, libvlc_marquee_Enable, 1);
	//libvlc_video_set_marquee_int(vlc_mediaPlayer, libvlc_marquee_Position, libvlc_position_center);
	//libvlc_video_set_marquee_int(vlc_mediaPlayer, libvlc_marquee_Refresh, 2000);
	//libvlc_video_set_marquee_int(vlc_mediaPlayer, libvlc_marquee_Size, 24);
	//libvlc_video_set_marquee_string(vlc_mediaPlayer, libvlc_marquee_Text, "这里是水印文本");
	libvlc_video_set_marquee_int(w->vlc_mediaPlayer, libvlc_marquee_Timeout, 5000);
	//libvlc_video_set_marquee_int(vlc_mediaPlayer, libvlc_marquee_Opacity, 255); // 不透明

	//获取事件管理器
	libvlc_event_manager_t *em = libvlc_media_player_event_manager(vlc_mediaPlayer);

	// 注册事件监听器
	libvlc_event_attach(em, libvlc_MediaPlayerTimeChanged, vlcEvents, this);
	libvlc_event_attach(em, libvlc_MediaPlayerEndReached, vlcEvents, this);
	libvlc_event_attach(em, libvlc_MediaPlayerStopped, vlcEvents, this);
	libvlc_event_attach(em, libvlc_MediaPlayerPlaying, vlcEvents, this);
	libvlc_event_attach(em, libvlc_MediaPlayerPaused, vlcEvents, this);

	libvlc_media_player_set_hwnd(vlc_mediaPlayer, (void *)ui.widgetShow->winId());

	QTimer::singleShot(1000, this, &showWidget::slotPlay);
}

void showWidget::slotPlay()
{
	if (vlc_mediaPlayer)
		libvlc_media_player_play(vlc_mediaPlayer);
}

void showWidget::slotPause()
{
	if (vlc_mediaPlayer)
		libvlc_media_player_pause(vlc_mediaPlayer);
}

void showWidget::slotStop()
{
	if (vlc_mediaPlayer)
		libvlc_media_player_stop(vlc_mediaPlayer);
}

void showWidget::slotValueChanged(int value)
{
	if (vlc_mediaPlayer)
		libvlc_audio_set_volume(vlc_mediaPlayer, value);
}

void showWidget::slotCurrentIndexChanged(int index)
{
	if (vlc_mediaPlayer)
		libvlc_media_player_set_rate(vlc_mediaPlayer, m_lstRate[index]);
}

void showWidget::slotActionTriggered(QAction *action)
{
	if (!vlc_mediaPlayer)
		return;

	if (action == m_default)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer,m_defalutRate);
	else if(action == m_16_9)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "16:9");
	else if (action == m_4_3)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "4:3");
	else if (action == m_1_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "1:1");
	else if (action == m_16_10)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "16:10");
	else if (action == m_2_21_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "221:100");
	else if (action == m_2_35_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "235:100");
	else if (action == m_2_38_1)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "238:100");
	else if (action == m_5_4)
		libvlc_video_set_aspect_ratio(vlc_mediaPlayer, "5:4");
}

//事件回调
void showWidget::vlcEvents(const libvlc_event_t *ev, void *param)
{
	showWidget *w = (showWidget*)param;
	//处理不同的事件
	switch (ev->type) {
	case libvlc_MediaPlayerTimeChanged:
	{
		//qDebug() << "VLC媒体播放器时间已更改";
		qint64 len = libvlc_media_player_get_time(w->vlc_mediaPlayer);
		libvlc_time_t lenSec = len / 1000;

		libvlc_time_t totalLen = libvlc_media_player_get_length(w->vlc_mediaPlayer);
		libvlc_time_t totalLenSec = totalLen / 1000;

		int thh, tmm, tss;
		thh = lenSec / 3600;
		tmm = (lenSec % 3600) / 60;
		tss = (lenSec % 60);
		QTime time(thh, tmm, tss);
		w->ui.lbCurTime->setText(time.toString("hh:mm:ss"));

		thh = totalLenSec / 3600;
		tmm = (totalLenSec % 3600) / 60;
		tss = (totalLenSec % 60);
		QTime TotalTime(thh, tmm, tss);
		w->ui.lbTotalTime->setText(TotalTime.toString("hh:mm:ss"));

		double pos = (double)lenSec / totalLenSec * 100;
		w->ui.horizontalSlider->setValue(pos);
	}
		break;
	case libvlc_MediaPlayerEndReached:
		qDebug() << "VLC播放完毕.";
		break;
	case libvlc_MediaPlayerStopped:
		qDebug() << "VLC停止播放";
		break;
	case libvlc_MediaPlayerPlaying:
		qDebug() << "VLC开始播放";
		break;
	case libvlc_MediaPlayerPaused:
		qDebug() << "VLC暂停播放";
		break;
	}
}

更多参考：

libVLC 事件机制-CSDN博客

libVLC windows开发环境搭建-CSDN博客

https://sunnnnnn666.blog.csdn.net/article/details/136854500

libVLC 元数据-CSDN博客

libVLC 添加图片和文本水印-CSDN博客