初学ffmpeg，想把视频的图片（帧）显示在Qt的界面上，参考网上例子，新建项目，目录：

代码：

//CVideoPlayer.h
#ifndef CVIDEOPLAYER_H
#define CVIDEOPLAYER_H
 
#include <QThread>
#include <QImage>
 
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavdevice/avdevice.h"
}
 
class CVideoPlayer: public QThread
{
    Q_OBJECT
 
public:
    CVideoPlayer();
    void videoDecode();
 
protected:
    void run();
 
signals:
    void signalGetOneFrame(QImage image);
    void signalDecodeError(int error);
 
};
 
#endif // CVIDEOPLAYER_H

//CVideoPlayer.cpp
#include "CVideoPlayer.h"
#include <QDebug>
 
CVideoPlayer::CVideoPlayer()
{
 
}
 
void CVideoPlayer::run()
{
    videoDecode();
}
 
void CVideoPlayer::videoDecode()
{
    char *filePath = "F:\\github\\QtPlayLearn\\win\\mp4\\lasa.mp4";
    AVFormatContext *pFormatCtx;
    AVCodecContext *pCodecCtx;
    AVCodec *pCodec;
    AVFrame *pFrame, *pFrameRGB;
    AVPacket *packet;
    uint8_t *outBuffer;
 
    static struct SwsContext *img_convert_ctx;
    unsigned int i;
    int videoStream, numBytes;
    int ret, got_picture;
    av_register_all();//初始化ffmpeg 调用了这个才能正常适用编码器和解码器
    //Allocate an AVFormatContext.
    pFormatCtx = avformat_alloc_context();
    if(0 != avformat_open_input(&pFormatCtx, filePath, nullptr, nullptr))
    {
        emit signalDecodeError(-1);
        return;
    }
 
    if(avformat_find_stream_info(pFormatCtx, nullptr))
    {
        emit signalDecodeError(-2);
        return;
    }
    videoStream = -1;
    //循环查找视频中包含的流信息，直到找到视频类型的流
    //便将其记录下来 保存到videoStream变量中
    //这里我们现在只处理视频流  音频流先不管他
    for(i = 0; i < pFormatCtx->nb_streams; ++i)
    {
        qDebug() << "pFormatCtx->streams[" << i << "]->codec->codec_type = " << pFormatCtx->streams[i]->codec->codec_type << endl;
        //0:视频类型 1:音频类型
        if(pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
            videoStream = i;
    }
    qDebug() << "videoStream===========" << videoStream << "  pFormatCtx->nb_streams==" << pFormatCtx->nb_streams << endl;
    //如果videoStream为-1 说明没有找到视频流
    if(videoStream == -1)
    {
        emit signalDecodeError(-3);
        return;
    }
    //查找解码器
    pCodecCtx = pFormatCtx->streams[videoStream]->codec;
    qDebug() << "pCodecCtx->codec_id===========" << pCodecCtx->codec_id << endl;
    //测试时这个值为27，查到枚举值对应的是AV_CODEC_ID_H264 ，即是H264压缩格式的文件。
    pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
    if(nullptr == pCodec)
    {
        emit signalDecodeError(-4);
        return;
    }
 
    //打开解码器
    if(avcodec_open2(pCodecCtx, pCodec, nullptr) < 0)
    {
        emit signalDecodeError(-5);
        return;
    }
 
    pFrame = av_frame_alloc();
    pFrameRGB = av_frame_alloc();
    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, \
                                     pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, \
                                     AV_PIX_FMT_RGB32, SWS_BICUBIC, nullptr, nullptr, nullptr);
 
    numBytes = avpicture_get_size(AV_PIX_FMT_RGB32, pCodecCtx->width, pCodecCtx->height);
    outBuffer = (uint8_t *)av_malloc(numBytes * sizeof(uint8_t));
    avpicture_fill((AVPicture *)pFrameRGB, outBuffer, AV_PIX_FMT_RGB32, pCodecCtx->width, pCodecCtx->height);
    int y_size = pCodecCtx->width * pCodecCtx->height;
    packet = (AVPacket *)malloc(sizeof(AVPacket));//分配一个packet
    av_new_packet(packet, y_size);//分配packet的数据
    av_dump_format(pFormatCtx, 0,  filePath, 0);//输出视频信息
 
    int index = 0;
    while (1)
    {
        if(av_read_frame(pFormatCtx, packet) < 0)
        {
            qDebug() << "index===============" << index;
            break;//这里认为视频读取完了
        }
        if(packet->stream_index == videoStream)
        {
            ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
            if(ret < 0)
            {
                emit signalDecodeError(-6);
                return;
            }
            if(got_picture)
            {
                sws_scale(img_convert_ctx, (uint8_t const * const *)pFrame->data,
                          pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
                ++index;
                //把这个RGB数据 用QImage加载
                QImage tempImage((uchar*)outBuffer, pCodecCtx->width, pCodecCtx->height, QImage::Format_RGB32);
                QImage image = tempImage.copy();//把图像复制一份 传递给界面显示
                qDebug() << "image.width==" << image.width() << "image.height==" << image.height();
                emit signalGetOneFrame(image);
                //if (index > 10)
                //    return; //这里我们就保存10张图片
            }
        }
        av_free_packet(packet);
    }
    av_free(outBuffer);
    av_free(pFrameRGB);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);
 
}

//mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include "CVideoPlayer.h"
#include <QImage>
 
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
    void initView();
    void initData();
 
public slots:
    void slotDecodeError(int error);
    void slotGetOneFrame(QImage image);
 
protected:
    void paintEvent(QPaintEvent *event);
 
private:
    Ui::MainWindow *ui;
    CVideoPlayer *m_pVideoPlayer;
    QImage m_Image;
};
#endif // MAINWINDOW_H

//mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <QPainter>
 
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    initView();
    initData();
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
 
void MainWindow::initView()
{
 
}
 
void MainWindow::initData()
{
    m_pVideoPlayer = new CVideoPlayer();
    connect(m_pVideoPlayer, SIGNAL(signalDecodeError(int)), this, SLOT(slotDecodeError(int)));
    connect(m_pVideoPlayer, SIGNAL(signalGetOneFrame(QImage)), this, SLOT(slotGetOneFrame(QImage)));
    m_pVideoPlayer->start();
}
 
void MainWindow::slotDecodeError(int error)
{
    qDebug() << "slotDecodeError======error====" << error;
}
 
void MainWindow::slotGetOneFrame(QImage image)
{
    m_Image = image;
    update();//调用update将执行 paintEvent函数
}
 
void MainWindow::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setBrush(Qt::black);
    painter.drawRect(0, 0, this->width(), this->height());//先画成黑色
    if(m_Image.size().width() <= 0)
        return;
    //将图像按比例缩放成和窗口一样大小
    QImage img = m_Image.scaled(this->size(), Qt::KeepAspectRatio);
    int x = this->width() - img.width();
    int y = this->height() - img.height();
    x /=  2;
    y /= 2;
    painter.drawImage(QPoint(x, y), img);
}

//main.cpp
#include "mainwindow.h"
 
#include <QApplication>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

 运行后即可播放视频：

现在只是播放出来， 播放的速度比原视频快，还需要同步：

https://blog.csdn.net/qq_40015157/article/details/122496675

源码下载 ： QtFFmpegPlayer.rar-其它文档类资源-CSDN下载

参考文档： 03Qt+ffmpeg视频播放之显示图片_chenyijun的专栏-CSDN博客_ffmpeg显示图片