Python 3.x 屏幕记录时间与使用opencv的PyQt中的实际使用时间不一致

最近，我正在写一个关于屏幕记录器的代码。本程序使用Python3.5+PyQt+Opencv3.2。 我有个问题。当我使用该程序录制10秒的视频时，实际录制的文件视频只有5秒，移动速度看起来更快（可能快2倍）。 我不知道为什么。有人能帮我吗？多谢各位

该计划的主要思想是：

单击开始按钮后，开始计时

在功能

captureScreen

中，捕获屏幕，然后写入视频文件

单击停止按钮后，停止

计时器

源代码放在这里

ui.py

mainDialog.py

# -*- coding: utf-8 -*-

__author__ = '350187947@qq.com'

import sys

from PyQt5.QtWidgets import QApplication, QDialog
from PyQt5.QtCore import Qt, QTimer
from ui import *
from PIL import ImageGrab
import numpy as np
import cv2

class MainDialog(QDialog,Ui_mainDialog):

    def __init__(self,parent=None):
        super(MainDialog,self).__init__(parent)
        # UI properties
        self.setupUi(self)
        self.setWindowFlags(Qt.WindowCloseButtonHint)
        self.stopBtn.setEnabled(False)
        # video parameter
        self.__fps = 25.0
        self.__filename = "1stTest.avi"
        self.__codecs = cv2.VideoWriter_fourcc(*"XVID")
        im = ImageGrab.grab()  # capture the screen
        frame = np.array(im)  # change the frame from Image to np array

        self.__height, self.__width, self.__depth = frame.shape  # get the shape of the frame
        print(self.__height, self.__width, self.__depth)

        self.__timer = QTimer(self)
        self.__timer.timeout.connect(self.capturing)

    def capturing(self):
        # self.__timer.setInterval(1000.0 / self.__fps)
        frame = self.captureScreen()
        self.videoWrite(self.__video,frame)


    def setFps(self, fps=25.0):
        self.__fps = fps

    def setFilename(self, filename):
        self.__filename = filename

    # 1' create a videowriter
    # 2' set timer intervel
    # 3' start timer

    def startBtn_clicked(self):
        self.stopBtn.setEnabled(True)
        self.startBtn.setEnabled(False)
        self.__video = cv2.VideoWriter(self.__filename, self.__codecs, self.__fps, (self.__width, self.__height), True) # Make a video writer
        self.__timer.start(1000/self.__fps)

    def stopBtn_clicked(self):
        self.__timer.stop()
        self.__video.release()
        self.stopBtn.setEnabled(False)
        self.startBtn.setEnabled(True)

    def captureScreen(self):
        # capture the screen
        im = ImageGrab.grab()
        # change the frame from Image to nparray
        frame = np.array(im)
        # convert the color from BGR to RGB
        frame2 = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        return frame2

    def videoWrite(self,video,frame):
        if not type(video)==type(cv2.VideoWriter()):
            raise TypeError('video type ERROR')
        if not isinstance(frame,np.ndarray):
            raise TypeError('frame type ERROR')
        video.write(frame)

if __name__ == '__main__':
    '''
    main function
    '''

    app = QApplication(sys.argv)
    mainDialog = MainDialog()
    mainDialog.show()
    sys.exit(app.exec_())

---

听起来您的源FPS与输出FPS不同。也许捕获和保存图像所需的时间比FPS长（我希望如此），并且如果系统忙，QTimer不会进行任何调用。。。这听起来可能更难，但也许您可以使用回调调用抓取图像并将其放入队列中，由另一个线程处理？谢谢。如果我减少fps，那么时间可能是正确的？如果我想获得更高的fps视频，我需要照你说的做？另一个问题，我想写一个屏幕记录程序，最好的解决方案是什么？我认为它应该至少有两个线程，一个用来抓取并放入队列，另一个用来写，但一般来说，这并不清楚，因为如果抓取的线程比另一个线程快，那么这可能会在一段时间后消耗大量内存。非常感谢您。我试试看。

# -*- coding: utf-8 -*-

__author__ = '350187947@qq.com'

import sys

from PyQt5.QtWidgets import QApplication, QDialog
from PyQt5.QtCore import Qt, QTimer
from ui import *
from PIL import ImageGrab
import numpy as np
import cv2

class MainDialog(QDialog,Ui_mainDialog):

    def __init__(self,parent=None):
        super(MainDialog,self).__init__(parent)
        # UI properties
        self.setupUi(self)
        self.setWindowFlags(Qt.WindowCloseButtonHint)
        self.stopBtn.setEnabled(False)
        # video parameter
        self.__fps = 25.0
        self.__filename = "1stTest.avi"
        self.__codecs = cv2.VideoWriter_fourcc(*"XVID")
        im = ImageGrab.grab()  # capture the screen
        frame = np.array(im)  # change the frame from Image to np array

        self.__height, self.__width, self.__depth = frame.shape  # get the shape of the frame
        print(self.__height, self.__width, self.__depth)

        self.__timer = QTimer(self)
        self.__timer.timeout.connect(self.capturing)

    def capturing(self):
        # self.__timer.setInterval(1000.0 / self.__fps)
        frame = self.captureScreen()
        self.videoWrite(self.__video,frame)


    def setFps(self, fps=25.0):
        self.__fps = fps

    def setFilename(self, filename):
        self.__filename = filename

    # 1' create a videowriter
    # 2' set timer intervel
    # 3' start timer

    def startBtn_clicked(self):
        self.stopBtn.setEnabled(True)
        self.startBtn.setEnabled(False)
        self.__video = cv2.VideoWriter(self.__filename, self.__codecs, self.__fps, (self.__width, self.__height), True) # Make a video writer
        self.__timer.start(1000/self.__fps)

    def stopBtn_clicked(self):
        self.__timer.stop()
        self.__video.release()
        self.stopBtn.setEnabled(False)
        self.startBtn.setEnabled(True)

    def captureScreen(self):
        # capture the screen
        im = ImageGrab.grab()
        # change the frame from Image to nparray
        frame = np.array(im)
        # convert the color from BGR to RGB
        frame2 = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        return frame2

    def videoWrite(self,video,frame):
        if not type(video)==type(cv2.VideoWriter()):
            raise TypeError('video type ERROR')
        if not isinstance(frame,np.ndarray):
            raise TypeError('frame type ERROR')
        video.write(frame)

if __name__ == '__main__':
    '''
    main function
    '''

    app = QApplication(sys.argv)
    mainDialog = MainDialog()
    mainDialog.show()
    sys.exit(app.exec_())