我打算把opencv作为我项目的一部分。我想从网络摄像头获取图像并处理它们。所以我使用了videocapture（）。当我使用这个时，摄像头没有响应。我在visual studio和jupyter notbook中尝试了同一个程序。两个程序的结果都是一样的。代码如下：

import cv2 
import matplotlib.pyplot as plt
key = cv2. waitKey(1)
webcam = cv2.VideoCapture(-1)
while True:
    try:
        check, frame = webcam.read()
        print(check) #prints true as long as the webcam is running
        #print(frame) #prints matrix values of each framecd 
        cv2.imshow("Capturing", frame)
        key = cv2.waitKey(1)
        if key == ord('s'): 
            cv2.imwrite(filename='saved_img.jpg', img=frame)
            webcam.release()
            img_new = cv2.imread('saved_img.jpg', cv2.IMREAD_GRAYSCALE)
            img_new = cv2.imshow("Captured Image", img_new)
            cv2.waitKey(1650)
            cv2.destroyAllWindows()
            print("Processing image...")
            img_ = cv2.imread('saved_img.jpg', cv2.IMREAD_ANYCOLOR)
            print("Converting RGB image to grayscale...")
            gray = cv2.cvtColor(img_, cv2.COLOR_BGR2GRAY)
            print("Converted RGB image to grayscale...")
            print("Resizing image to 28x28 scale...")
            img_ = cv2.resize(gray,(28,28))
            print("Resized...")
            img_resized = cv2.imwrite(filename='saved_img-final.jpg', img=img_)
            print("Image saved!")
            plt.show()
            break
        elif key == ord('q'):
            print("Turning off camera.")
            webcam.release()
            print("Camera off.")
            print("Program ended.")
            cv2.destroyAllWindows()
            break
        
    except(KeyboardInterrupt):
        print("Turning off camera.")
        webcam.release()
        print("Camera off.")
        print("Program ended.")
        cv2.destroyAllWindows()
        break

的

print(check)
print(frame)

正在返回

False
None

我甚至尝试了videocapture（0）和videocapture（-1）是问题存在于我的系统或代码如何解决这个问题。