如何使用 OpenCV 和 QThread 在 pyqt5 gui 中录制来自网络摄像头的视频？

Question

我正在尝试使 pyqt5 Gui 显示网络摄像头实时提要，同时记录提要，并在关闭时将其保存在本地。我设法在 pyqt gui 中使用 Timer(QTimer) 实现了这一点，但是当我尝试使用 Qthread（我真正需要的）实现它时，只有实时提要在工作。

每当我添加录制视频所需的代码和运行程序时，它会说 Python 已停止工作 并关闭。这是我的代码：

import cv2
import sys
from PyQt5.QtWidgets import QWidget, QLabel, QApplication, QVBoxLayout
from PyQt5.QtCore import QThread, Qt, pyqtSignal, pyqtSlot
from PyQt5.QtGui import QImage, QPixmap


class Thread(QThread):
    changePixmap = pyqtSignal(QImage)

    def run(self):
        self.cap = cv2.VideoCapture(0)

        self.width = int(self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        self.height = int(self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

        self.codec = cv2.VideoWriter_fourcc('X', 'V', 'I', 'D')
        self.writer = cv2.VideoWriter('output.avi', self.codec, 30.0, (self.width, self.height))

        while self.cap.isOpened():
            ret, self.frame = self.cap.read()
            if ret:
                self.frame = cv2.flip(self.frame, 1)
                rgbimage = cv2.cvtColor(self.frame, cv2.COLOR_BGR2RGB)
                h, w, ch = rgbimage.shape
                bytesPerLine = ch * w
                convertToQtFormat = QImage(rgbimage.data, w, h, bytesPerLine, QImage.Format_RGB888)
                p = convertToQtFormat.scaled(640, 480, Qt.KeepAspectRatio)
                self.changePixmap.emit(p)


class MyApp(QWidget):
    def __init__(self):
        super(MyApp, self).__init__()
        self.title = 'Camera'
        self.initUI()

    def initUI(self):
        self.label = QLabel(self)
        lay = QVBoxLayout()
        lay.addWidget(self.label)
        self.setLayout(lay)

        self.th = Thread()
        self.th.changePixmap.connect(self.setImage)
        self.th.start()
        self.show()

    @pyqtSlot(QImage)
    def setImage(self, image):
        self.label.setPixmap(QPixmap.fromImage(image))
        self.th.writer.write(image)


def main():
    app = QApplication(sys.argv)
    ex = MyApp()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

我也尝试将 .write() 放在 Thread class 的运行() 中，这也显示了同样的错误。你们能指出我做错了什么以及如何让它发挥作用吗？我是 python 和 pyqt 的新手。提前致谢。

Answer 1

您需要分离线程。第一个线程用于信号，第二个线程用于记录，主线程用于 GUI。试试下面的代码。有一个 start/stop 记录的按钮。

import sys
import cv2

from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QLabel, QVBoxLayout
from PyQt5.QtGui import QImage, QPixmap
from PyQt5.QtCore import QTimer, QThread, pyqtSignal, pyqtSlot
from PyQt5 import QtWidgets, QtCore, QtGui

#https://ru.whosebug.com/a/1150993/396441

class Thread1(QThread):
    changePixmap = pyqtSignal(QImage)
    
    def __init__(self, *args, **kwargs):
        super().__init__()

    def run(self):
        self.cap1 = cv2.VideoCapture(0, cv2.CAP_DSHOW)
        self.cap1.set(3,480)
        self.cap1.set(4,640)
        self.cap1.set(5,30)
        while True:
            ret1, image1 = self.cap1.read()
            if ret1:
                im1 = cv2.cvtColor(image1, cv2.COLOR_BGR2RGB)
                height1, width1, channel1 = im1.shape
                step1 = channel1 * width1
                qImg1 = QImage(im1.data, width1, height1, step1, QImage.Format_RGB888)
                self.changePixmap.emit(qImg1)

class Thread2(QThread):
    
    def __init__(self, *args, **kwargs):
        super().__init__()
        self.active = True

    def run(self):
        if self.active:            
            self.fourcc = cv2.VideoWriter_fourcc(*'XVID') 
            self.out1 = cv2.VideoWriter('output.avi', self.fourcc, 30, (640,480))
            self.cap1 = cv2.VideoCapture(0, cv2.CAP_DSHOW)
            self.cap1.set(3, 480)
            self.cap1.set(4, 640)
            self.cap1.set(5, 30)
            while self.active:                      
                ret1, image1 = self.cap1.read()
                if ret1:
                    self.out1.write(image1)     
                self.msleep(10)                      

    def stop(self):
        self.out1.release()

       
class MainWindow(QWidget):
    
    def __init__(self):
        super().__init__()
        self.resize(660, 520)
        self.control_bt = QPushButton('START')
        self.control_bt.clicked.connect(self.controlTimer)
        self.image_label = QLabel()
        self.saveTimer = QTimer()
        self.th1 = Thread1(self)
        self.th1.changePixmap.connect(self.setImage)
        self.th1.start()
        
        vlayout = QVBoxLayout(self)
        vlayout.addWidget(self.image_label)
        vlayout.addWidget(self.control_bt)   

    @QtCore.pyqtSlot(QImage)
    def setImage(self, qImg1):
        self.image_label.setPixmap(QPixmap.fromImage(qImg1))

    def controlTimer(self):
        if not self.saveTimer.isActive():
            # write video
            self.saveTimer.start()
            self.th2 = Thread2(self)
            self.th2.active = True                                
            self.th2.start()
            # update control_bt text
            self.control_bt.setText("STOP")
        else:
            # stop writing
            self.saveTimer.stop()
            self.th2.active = False                   
            self.th2.stop()                         
            self.th2.terminate()                    
            # update control_bt text
            self.control_bt.setText("START")

if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainWindow = MainWindow()
    mainWindow.show()
    sys.exit(app.exec_())

Answer 2

您将 .write() 放在线程的运行() 中 class 是正确的方法。

喜欢：

...
        while self.cap.isOpened():
            ret, self.frame = self.cap.read()
            if ret:
                self.frame = cv2.flip(self.frame, 1)
                rgbimage = cv2.cvtColor(self.frame, cv2.COLOR_BGR2RGB)
                h, w, ch = rgbimage.shape
                bytesPerLine = ch * w
                convertToQtFormat = QImage(
                    rgbimage.data, w, h, bytesPerLine, QImage.Format_RGB888)
                p = convertToQtFormat.scaled(640, 480, Qt.KeepAspectRatio)

                # put your writer() here, make sure your param is frame
                # not converted to QtImage format
                self.writer.write(rgbimage)

                self.changePixmap.emit(p)
...

如何使用 OpenCV 和 QThread 在 pyqt5 gui 中录制来自网络摄像头的视频？

How to record the video from a webcam in a pyqt5 gui using OpenCV and QThread?

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