在上一节中,我们讲解了如何使用QWidget渲染每一帧视频数据。
由于我们不停的生成的是QImage对象,因此对 CPU 负荷较高。其实在绘制这块我们可以使用 OpenGL去绘制,利用 GPU 减轻 CPU 计算负荷,本节讲解使用OpenGL来绘制每一帧视频数据。
libVLC 提取视频帧使用QWidget渲染-CSDN博客
以下是操作流程:
1.初始化 libVLC 实例。
cpp
vlc_base = libvlc_new(0, NULL);
2.创建一个媒体播放器。
cpp
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;
}
3.设置视频回调。
cpp
libvlc_video_set_format_callbacks(vlc_mediaPlayer, setup, NULL);
// 设置自定义视频输出
libvlc_video_set_callbacks(vlc_mediaPlayer, lock, unlock, display, NULL);
4.提取视频帧数据,回调给OpenGL显示。
cpp
static void unlock(void *opaque, void *picture, void *const *planes) {
// 这里可以释放视频帧的锁
uint8_t *buffer = (uint8_t *)*planes; //planes即为帧数据
//QImage image((unsigned char*)buffer, g_frame->width, g_frame->height, QImage::Format_ARGB32);
m_this->m_videoFunc(buffer);
g_frame->mutex.unlock();
}
声明了两个OpenGL接口回调。
cpp
//视频每一帧数据回调
typedef std::function<void(uint8_t*)> VideoDataFunc;
//视频宽、高。回调
typedef std::function<void(int, int)> VideoInfoFunc;
设置回调。
cpp
//视频数据
m_videoFunc = std::bind(&WOpenGLWidget::slotReceiveVideoData, ui.openGLWidget,
std::placeholders::_1);
//视频信息
m_videoInfoFunc = std::bind(&WOpenGLWidget::slotOpenVideo, ui.openGLWidget,
std::placeholders::_1, std::placeholders::_2);
使用回调。
cpp
static void unlock(void *opaque, void *picture, void *const *planes) {
// 这里可以释放视频帧的锁
uint8_t *buffer = (uint8_t *)*planes; //planes即为帧数据
//QImage image((unsigned char*)buffer, g_frame->width, g_frame->height, QImage::Format_ARGB32);
m_this->m_videoFunc(buffer);
g_frame->mutex.unlock();
}
static unsigned setup(void **opaque, char *chroma,
unsigned *width, unsigned *height,
unsigned *pitches,
unsigned *lines)
{
qDebug() << "chroma:" << QString(chroma) << "width:" << *width << ", height:" << *height;
/* 开辟存放图像数据的内存块 */
if (g_frame)
{
if (g_frame->pixels)
{
delete[] g_frame->pixels;
g_frame->pixels = NULL;
}
delete g_frame;
g_frame = NULL;
}
int w = *width;
int h = *height;
g_frame = new Frame;
g_frame->pixels = new uchar[w * h * 4]; // 申请大小也为4通道的像素
memset(g_frame->pixels, 0, w * h * 4);
memcpy(chroma, "RV32", 4);
g_frame->width = w;
g_frame->height = h;
*pitches = w * 4;
*lines = h;
m_this->m_videoInfoFunc(w, h);
return 1;
}
opengl完全没有基础的同学,请先学习以下的几篇文章,我们只需要了解2D图像如何渲染就行。
首先继承QOpenGLWidget类,重写paintGL()、resizeGL()、initializeGL()方法。
本示例演示使用opengles2来渲染,渲染rgba的数据。
以下是封装好的WOpenGLWidget类,使用提升的方式,提升为以下这个类就行了。
cpp
#ifndef WOPENGLWIDGET_H
#define WOPENGLWIDGET_H
#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QOpenGLTexture>
#include <QImage>
#include <QOpenGLShaderProgram>
#include <QOpenGLShader>
#include <QDebug>
#include <QImage>
#include <QMouseEvent>
#include <QSet>
#include <QPainter>
#include <QMutex>
#include <QOpenGLBuffer>
class OpenGLDisplayImpl
{
public:
OpenGLDisplayImpl()
{
texture = NULL;
videoW = 0;
videoH = 0;
}
unsigned char *buffer = {0};
QOpenGLTexture* texture;
GLsizei videoW, videoH;
};
class WOpenGLWidget : public QOpenGLWidget,public QOpenGLFunctions
{
Q_OBJECT
public:
WOpenGLWidget(QWidget* parent = Q_NULLPTR);
~WOpenGLWidget();
public:
void slotOpenVideo(int width,int height);
void slotReceiveVideoData(uint8_t* buffer);
void clear();
void deleteBuffer();
protected:
virtual void initializeGL();
virtual void paintGL();
virtual void resizeGL(int w, int h);
private:
QOpenGLShaderProgram *m_program = nullptr; //着色器程序
QOpenGLBuffer VBO, EBO;
OpenGLDisplayImpl *m_impl = nullptr;
bool m_isShowVideo = false;
QMutex m_mux;
};
#endif // WOPENGLWIDGET_H
#include "WOpenGLWidget.h"
#include <QDebug>
#include <QTimer>
#include <QElapsedTimer>
static float vertices[] = {
// ---- 位置 ---- - 纹理坐标 -
1.0f, 1.0f, 0.0f, 1.0f, 1.0f, // 右上
1.0f, -1.0f, 0.0f, 1.0f, 0.0f, // 右下
-1.0f, -1.0f, 0.0f, 0.0f, 0.0f, // 左下
-1.0f, 1.0f, 0.0f, 0.0f, 1.0f // 左上
};
static unsigned int indices[] = {
0, 1, 3,
1, 2, 3
};
WOpenGLWidget::WOpenGLWidget(QWidget* parent)
: QOpenGLWidget(parent)
, m_impl(new OpenGLDisplayImpl)
, EBO(QOpenGLBuffer::IndexBuffer)
{
}
WOpenGLWidget::~WOpenGLWidget()
{
clear();
if (m_impl->texture)
{
m_impl->texture->destroy();
}
delete m_impl;
m_impl = nullptr;
}
void WOpenGLWidget::slotOpenVideo(int width, int height)
{
qDebug() << "slotOpenVideo";
m_mux.lock();
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClear(GL_COLOR_BUFFER_BIT);
m_isShowVideo = false;
m_impl->videoW = width;
m_impl->videoH = height;
deleteBuffer();
resize(this->width(), this->height());
m_isShowVideo = true;
m_mux.unlock();
}
void WOpenGLWidget::slotReceiveVideoData(uint8_t* yuvBuffer)
{
if (!m_impl)
return;
m_mux.lock();
if(!m_impl->buffer)
m_impl->buffer = new unsigned char[m_impl->videoW * m_impl->videoH * 4];//y
memcpy(m_impl->buffer, yuvBuffer, m_impl->videoW * m_impl->videoH * 4);
update();
m_mux.unlock();
}
void WOpenGLWidget::clear()
{
m_mux.lock();
deleteBuffer();
m_isShowVideo = false;
m_mux.unlock();
}
void WOpenGLWidget::deleteBuffer()
{
if (m_impl)
{
if (m_impl->buffer) {
delete m_impl->buffer;
m_impl->buffer= nullptr;
}
}
}
void WOpenGLWidget::initializeGL()
{
m_mux.lock();
initializeOpenGLFunctions();
m_program = new QOpenGLShaderProgram();
m_program->addShaderFromSourceFile(QOpenGLShader::Vertex,":/shaders/shaders/shapes.vert");
m_program->addShaderFromSourceFile(QOpenGLShader::Fragment,":/shaders/shaders/shapes.frag");
bool success = m_program->link();
if (!success)
qDebug() << "ERR:" << m_program->log();
VBO.create();
EBO.create();
VBO.bind();
EBO.bind();
VBO.allocate(vertices, 20 * sizeof(float));
EBO.allocate(indices, 6 * sizeof(unsigned int));
m_impl->texture = new QOpenGLTexture(QOpenGLTexture::Target2D);
m_impl->texture->create();
m_impl->texture->setMinificationFilter(QOpenGLTexture::Nearest);
m_impl->texture->setMinificationFilter(QOpenGLTexture::Linear);
m_impl->texture->setWrapMode(QOpenGLTexture::ClampToEdge);
m_mux.unlock();
// 启动定时器
QTimer *ti = new QTimer(this);
connect(ti, &QTimer::timeout, this, [=] {
update();
});
ti->start(100);
}
void WOpenGLWidget::paintGL()
{
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
m_mux.lock();
if (m_isShowVideo)
{
VBO.bind();
EBO.bind();
m_program->bind();
m_impl->texture->bind(0);
m_program->setUniformValue("texture", 0);
int vertexLocation = m_program->attributeLocation("position");
m_program->enableAttributeArray(vertexLocation);
m_program->setAttributeBuffer(vertexLocation, GL_FLOAT, 0, 3, 5 * sizeof(float));
int texcoordLocation = m_program->attributeLocation("texCoord");
m_program->enableAttributeArray(texcoordLocation);
m_program->setAttributeBuffer(texcoordLocation, GL_FLOAT, 3 * sizeof(float), 2, 5 * sizeof(float));
//激活纹理单元0
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, m_impl->texture->textureId());
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_impl->videoW,
m_impl->videoH, 0, GL_BGRA, GL_UNSIGNED_BYTE, m_impl->buffer);
//设置纹理环绕方式
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glDrawElements(GL_TRIANGLES,6, GL_UNSIGNED_INT,0);
if(m_impl->texture)
m_impl->texture->release();
m_program->release();
}
m_mux.unlock();
}
void WOpenGLWidget::resizeGL(int w, int h)
{
// 设置视口
//glViewport(0, 0, w, h);
}
着色器如下所示。
cpp
//shapes.vert
#ifdef GL_ES
precision mediump int;
precision mediump float;
#endif
attribute vec3 position;
attribute vec2 texCoord;
varying vec2 outTexCoord;
void main()
{
gl_Position = vec4(position,1.0);
outTexCoord = vec2(texCoord.x, 1.0 - texCoord.y);
}
//shapes.frag
#ifdef GL_ES
// Set default precision to medium
precision mediump int;
precision mediump float;
#endif
uniform sampler2D texture;
varying vec2 outTexCoord;
void main()
{
vec3 rgb = texture2D(texture, outTexCoord);
gl_FragColor = vec4(rgb, 1);
}
ui界面如下图所示。
运行截图:
完整代码:
cpp
#pragma once
#include <QtWidgets/QWidget>
#include "ui_showWidget.h"
#include <QMenu>
#include <QActionGroup>
#include <vlc/vlc.h>
#include <QDebug>
#include <QFileDialog>
#include <QThread>
#include <QMouseEvent>
#include <QKeyEvent>
//视频每一帧数据回调
typedef std::function<void(uint8_t*)> VideoDataFunc;
//视频宽、高。回调
typedef std::function<void(int, int)> VideoInfoFunc;
enum Rate
{
Rate2X,
Rate1_5X,
Rate1_25X,
Rate1_0X,
Rate0_75X,
Rate0_5X
};
class showWidget : public QWidget
{
Q_OBJECT
public:
showWidget(QWidget *parent = nullptr);
~showWidget();
public:
VideoDataFunc m_videoFunc;
VideoInfoFunc m_videoInfoFunc;
private slots:
void slotOpenFile();
void slotPlay();
void slotPause();
void slotStop();
void slotValueChanged(int value);
void slotCurrentIndexChanged(int index);
private:
//事件处理回调
static void vlcEvents(const libvlc_event_t *ev, void *param);
private:
Ui::showWidgetClass ui;
private:
libvlc_instance_t *vlc_base = nullptr;
libvlc_media_t *vlc_media = nullptr;
libvlc_media_player_t *vlc_mediaPlayer = nullptr;
QList<float> m_lstRate;
QList<QString> m_lstAudioDevice;
};
//=====================================================
#include "showWidget.h"
#include <QTimer>
#include <QTime>
#include <QMutex>
#include <stdlib.h>
#pragma execution_character_set("utf-8")
static showWidget* m_this = nullptr;
struct Frame
{
int width;
int height;
uchar * pixels;
QMutex mutex;
};
static Frame *g_frame = nullptr;
// 自定义视频输出模块的回调函数
static void *lock(void *opaque, void **planes) {
g_frame->mutex.lock();
*planes = g_frame->pixels;
return 0;
}
static void unlock(void *opaque, void *picture, void *const *planes) {
// 这里可以释放视频帧的锁
uint8_t *buffer = (uint8_t *)*planes; //planes即为帧数据
//QImage image((unsigned char*)buffer, g_frame->width, g_frame->height, QImage::Format_ARGB32);
m_this->m_videoFunc(buffer);
g_frame->mutex.unlock();
}
static void display(void *opaque, void *picture) {
// 这里可以进行视频帧的显示或其他处理
(void)opaque;
}
static unsigned setup(void **opaque, char *chroma,
unsigned *width, unsigned *height,
unsigned *pitches,
unsigned *lines)
{
qDebug() << "chroma:" << QString(chroma) << "width:" << *width << ", height:" << *height;
/* 开辟存放图像数据的内存块 */
if (g_frame)
{
if (g_frame->pixels)
{
delete[] g_frame->pixels;
g_frame->pixels = NULL;
}
delete g_frame;
g_frame = NULL;
}
int w = *width;
int h = *height;
g_frame = new Frame;
g_frame->pixels = new uchar[w * h * 4]; // 申请大小也为4通道的像素
memset(g_frame->pixels, 0, w * h * 4);
memcpy(chroma, "RV32", 4);
g_frame->width = w;
g_frame->height = h;
*pitches = w * 4;
*lines = h;
m_this->m_videoInfoFunc(w, h);
return 1;
}
showWidget::showWidget(QWidget *parent)
: QWidget(parent)
{
ui.setupUi(this);
m_this = this;
this->setWindowTitle("视频播放器");
vlc_base = libvlc_new(0, NULL);
ui.cbxRate->setCurrentIndex(Rate1_0X);
m_lstRate << 2.0 << 1.5 << 1.25 << 1.0 << 0.75 << 0.5;
ui.btnOpen->setFocusPolicy(Qt::NoFocus);
ui.btnPlay->setFocusPolicy(Qt::NoFocus);
ui.btnPause->setFocusPolicy(Qt::NoFocus);
ui.btnStop->setFocusPolicy(Qt::NoFocus);
ui.hSliderVolumn->setFocusPolicy(Qt::NoFocus);
ui.cbxRate->setFocusPolicy(Qt::NoFocus);
//视频数据
m_videoFunc = std::bind(&WOpenGLWidget::slotReceiveVideoData, ui.openGLWidget,
std::placeholders::_1);
//视频信息
m_videoInfoFunc = std::bind(&WOpenGLWidget::slotOpenVideo, ui.openGLWidget,
std::placeholders::_1, std::placeholders::_2);
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::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_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;
}
libvlc_video_set_format_callbacks(vlc_mediaPlayer, setup, NULL);
// 设置自定义视频输出
libvlc_video_set_callbacks(vlc_mediaPlayer, lock, unlock, display, NULL);
// 等待元数据加载完成
libvlc_media_parse(vlc_media);
// 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
}
}
//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);
QTimer::singleShot(1000, this, &showWidget::slotPlay);
libvlc_video_filter_list_get(vlc_base);
}
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]);
}
//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:
Qt+FFmpeg+opengl从零制作视频播放器-7.OpenGL播放视频_qt opengl视频播放器-CSDN博客