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

//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();
  }
}