Python+Opencv 调用USB摄像头（一）

一.最简单的调用笔记本内置相机

import cv2
#引入库
cap = cv2.VideoCapture(0)
while True:
    ret, frame = cap.read()
    cv2.imshow("Video", frame)
#读取内容
    if cv2.waitKey(10) == ord("q"):
        break
        
#随时准备按q退出
cap.release()
cv2.destroyAllWindows()
#停止调用，关闭窗口

import cv2
import os
#引入库

print("=============================================")
print("=  热键(请在摄像头的窗口使用)：             =")
print("=  z: 更改存储目录                          =")
print("=  x: 拍摄图片                              =")
print("=  q: 退出                                  =")
print("=============================================")
#提醒用户操作字典

class_name = input("请输入存储目录：")
while os.path.exists(class_name):
    class_name = input("目录已存在！请输入存储目录：")
os.mkdir(class_name)
#存储

index = 1
cap = cv2.VideoCapture(0)
width = 640
height = 480
w = 360
cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
crop_w_start = (width-w)//2
crop_h_start = (height-w)//2
print(width, height)
#设置特定值

while True:
    ret, frame = cap.read()
   
    frame = frame[crop_h_start:crop_h_start+w, crop_w_start:crop_w_start+w]
    #没理解？

    frame = cv2.flip(frame,1,dst=None)
    #镜像显示
    cv2.imshow("capture", f