采用opencv读取视频并且显示和保存视频

    1. import cv2 as cv
    4. # 读取摄像头的视频
    5. def readVideo():
    6.     # 打开电脑摄像头
    7.     cap = cv.VideoCapture(0)
    8.     # 如果摄像头没有打开
    9.     if not cap.isOpened():
    10.         print("cannot open video")
    11.         exit()
    12.     while True:
    13.         # 逐桢播放 ret返回值true或者false  true表示读取到了  false表示未读取到
    14.         ret, frame = cap.read()
    15.         if not ret:
    16.             # 无法读取到
    17.             print("can't receive frame")
    18.             break
    19.         gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
    20.         cv.imshow("frame", gray)
    21.         # 输入q的时候进行停止
    22.         if cv.waitKey(1) == ord('q'):
    23.             break
    24.     cap.release()
    25.     cv.destroyAllWindows()
    28. # 读取摄像头的视频
    29. def writeVideo():
    30.     cap = cv.VideoCapture(0)
    31.     # 定义编解码器并创建VideoWriter对象
    32.     fourcc = cv.VideoWriter_fourcc(*'XVID')
    33.     out = cv.VideoWriter('output.avi', fourcc, 20.0, (640, 480))
    34.     while cap.isOpened():
    35.         ret, frame = cap.read()
    36.         if not ret:
    37.             print("Can't receive frame (stream end?). Exiting ...")
    38.             break
    39.         # 图像翻转
    40.         frame = cv.flip(frame, -1)
    41.         # 写翻转的框架
    42.         out.write(frame)
    43.         cv.imshow('frame', frame)
    44.         if cv.waitKey(1) == ord('q'):
    45.             break
    46.     # 完成工作后释放所有内容
    47.     cap.release()
    48.     out.release()
    49.     cv.destroyAllWindows()
    52. if __name__ == '__main__':
    53.     # readVideo()
    54.     writeVideo()