读取摄像头内容，然后保存一段十秒钟的视频。

import cv2
cameraCapture = cv2.VideoCapture(0)
fps = 30 # an assumption
size = (int(cameraCapture.get(cv2.cv.CV_CAP_PROP_FRAME_WIDTH)),int(cameraCapture.get(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT)))
videoWriter = cv2.VideoWriter('MyOutputVid.avi', cv2.cv.CV_FOURCC('I','4','2','0'), fps, size)
success, frame = cameraCapture.read()
numFramesRemaining = 10 * fps - 1
while success and numFramesRemaining > 0:
    videoWriter.write(frame)
    success, frame = cameraCapture.read()
    numFramesRemaining -= 1