open a videowriter based on a videocapture

Several things are tricky about this one:
  • the get() function in opencv always returns a float, so we have to cast it to the appropriate values.
  • the get() function flags are defined in cv, and not cv2.
  • there is no Size() object in python, instead we need a tuple of ints
  • the size the video expects is in the order of width, height – so columns, rows
import cv import cv2 import sys samplecap = cv2.VideoCapture(filename) if not samplecap.isOpened(): print "Error: could not open capture " + filename + ".\n" sys.exit() framesize = (int(samplecap.get(cv.CV_CAP_PROP_FRAME_WIDTH)), int(samplecap.get(cv.CV_CAP_PROP_FRAME_HEIGHT))) samplewriter = cv2.VideoWriter(), int(samplecap.get(cv.CV_CAP_PROP_FOURCC)), int(samplecap.get(cv.CV_CAP_PROP_FPS)), framesize)