import cv2
import numpy
capture = cv2.VideoCapture(0)
i=0
while True:
    ret, new_frame = capture.read()
    if ret:
        cv2.imwrite('frame_%d.jpg' % i, new_frame)
        diff = frame - last_frame
        percent_motion = numpy.count_nonzero(diff) / float(frame.size)
        print 'percent motion seems to be %.2f' % (percent_motion)
        i += 1
    else:
        print 'seems like we\'re at the end of the file'
        break