import cv2import numpy as np# https://github.com/Itseez/opencv/tree/master/data/haarcascadeface_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')videocapture = cv2.VideoCapture(0)scale_factor = 1.3while 1:    ret, pic = videocapture.read()    faces = face_cascade.detectMultiScale(pic, scale_factor, 5)    for(x, y, w, h) in faces:        cv2.rectangle(pic, (x, y), (x + w, y + h), (255, 0, 0), 2)        font = cv2.FONT_HERSHEY_SIMPLEX        cv2.putText(pic, 'Me', (x, y), font, 2, (255, 255, 255), 2, cv2.LINE_AA)        print("Number of faces found {} " .format(len(faces)))        cv2.imshow('faces', pic)        k = cv2.waitKey(30) & 0xff        if k == 2:            break            cv2.destroyAllWindows()[警告：0] 全局 C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-2y91i_7w\opencv\modules\videoio\src\cap_msmf.cpp (435) `anonymous-namespace':: SourceReaderCB::~SourceReaderCB 終止異步回調