QT+Opencv实现视频流播放

1.简单流程

首先通过opencv打开视频流，获取到数据帧，然后将数据帧转换为QT可识别的图像，显示到QT界面上。

2.opencv解码线程源码

//DecodeOpencv.h
#pragma once
#include <QThread>
#include <QObject>
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
class DecodeOpencv : public QThread
{
    Q_OBJECT
Q_SIGNALS:
    void sigSendFrame(cv::Mat mat);
public:
    DecodeOpencv(QObject *parent = nullptr);
    ~DecodeOpencv();
public:
    void setUrl(QString url);
    void setStoped(bool stop);
protected:
    void run();
private:
    QString m_rtsp;
    bool m_isStop = false;
};
//DecodeOpencv.cpp
#include "DecodeOpencv.h"
#include <QDebug>
DecodeOpencv::DecodeOpencv(QObject *parent)
    : QThread(parent)
{
    qRegisterMetaType<cv::Mat>("cv::Mat");
}
DecodeOpencv::~DecodeOpencv()
{
    m_isStop = true;
}
void DecodeOpencv::setUrl(QString url)
{
    m_rtsp = url;
}
void DecodeOpencv::setStoped(bool stop)
{
    m_isStop = stop;
}
void DecodeOpencv::run()
{
    cv::VideoCapture cap;
    if (m_rtsp.isEmpty())
    {
        qDebug() << "未找到视频流地址";
        return;
    }
    bool suc = false;
    if (m_rtsp.contains("localhost:camera"))
    {
        suc = cap.open(0); //打开本地摄像头
    }
    else
    {
        suc = cap.open(m_rtsp.toStdString()); //打开网络流地址
    }
    if (!suc)
    {
        qDebug() << "播放失败";
        return;
    }
    while (true)
    {
        if (!m_isStop)
        {
            cv::Mat frame;
            cap >> frame;
            if (frame.empty())
            {
                qDebug() << "播放帧解析失败";
                continue;
            }
            emit sigSendFrame(frame);
        }
        else
        {
            qDebug() << "停止播放";
            break;
        }
    }
}

3.QT界面

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//ShowMatWidget.h
#pragma once
#include <QWidget>
#include "ui_ShowMatWidget.h"
#include "DecodeOpencv.h"
class ShowMatWidget : public QWidget
{
    Q_OBJECT
public:
    ShowMatWidget(QWidget *parent = Q_NULLPTR);
    ~ShowMatWidget();
private Q_SLOTS:
    void slotBtnConnected();
    void slotGetFrame(cv::Mat mat);
    QImage cvMat2QImage(const cv::Mat& mat);
private:
    Ui::ShowMatWidget ui;
    DecodeOpencv *m_thread = nullptr;
};
//ShowMatWidget.cpp
#include "ShowMatWidget.h"
#include <QDebug>
ShowMatWidget::ShowMatWidget(QWidget *parent)
    : QWidget(parent)
{
    ui.setupUi(this);
    m_thread = new DecodeOpencv(this);
    connect(m_thread, &DecodeOpencv::sigSendFrame, this, &ShowMatWidget::slotGetFrame);
    connect(ui.pushButton, &QPushButton::clicked, this, &ShowMatWidget::slotBtnConnected);
}
ShowMatWidget::~ShowMatWidget()
{
}
void ShowMatWidget::slotBtnConnected()
{
    m_thread->setUrl(ui.lineEdit->text());
    m_thread->start();
}
void ShowMatWidget::slotGetFrame(cv::Mat mat)
{
    QImage image = cvMat2QImage(mat);
    ui.label->setPixmap(QPixmap::fromImage(image));
}
QImage ShowMatWidget::cvMat2QImage(const cv::Mat& mat)
{
    //8位，通道数为1
    if (mat.type() == CV_8UC1)
    {
        QImage image(mat.cols, mat.rows, QImage::Format_Indexed8);
        image.setColorCount(256);
        for (int i = 0; i < 256; i++)
        {
            image.setColor(i, qRgb(i, i, i));
        }
        uchar *pSrc = mat.data;
        for (int row = 0; row < mat.rows; row++)
        {
            uchar *pDest = image.scanLine(row);
            memcpy(pDest, pSrc, mat.cols);
            pSrc += mat.step;
        }
        return image;
    }
    //8位，通道数为3
    else if (mat.type() == CV_8UC3)
    {
        const uchar *pSrc = (const uchar*)mat.data;
        QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_RGB888);
        return image.rgbSwapped();
    }
    //8位，通道数为4
    else if (mat.type() == CV_8UC4)
    {
        qDebug() << "CV_8UC4";
        const uchar *pSrc = (const uchar*)mat.data;
        QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_ARGB32);
        return image.copy();
    }
    //32位，通道数为3
    else if (mat.type() == CV_32FC3)
    {
        cv::Mat temp;
        mat.convertTo(temp, CV_8UC3);
        const uchar *pSrc = (const uchar*)temp.data;
        QImage image(pSrc, temp.cols, temp.rows, temp.step, QImage::Format_RGB888);
        return image.rgbSwapped();
    }
    else
    {
        qDebug() << "ERROR: Mat could not be converted to QImage.";
        return QImage();
    }
}