"""

This is a simple program to play a video using Opencv. This actually demonstrate

some problems. For example, run this program on

/home/julien/work/cmu_data/data/S1_brownies/videos/videos/out6510211.avi

And play this file in VLC as well.

At the beginning, you'll notice that the opencv version skip some frames when

the light is turned on (if we actually write all frames to disk, it turns

out these frames are the last one fetched by opencv for some reason).

So OpenCV doesn't seem really reliable to play video...

"""

import sys

import os

import cv2

def main(videofile):

  print "Playing %s", videofile

  assert os.path.exists(videofile)

  capture = cv2.VideoCapture(videofile)

  # This is a CRUCIAL LINE. Without it, OpenCV will start playing at some random

  # position

  capture.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 0)

  (status, frame) = capture.read()

  while frame is not None:

    cv2.imshow("Frame", frame)

    key = cv2.waitKey()

    if key == 27:

      break

    (status, frame) = capture.read()

if __name__ == "__main__":

  main(sys.argv[1])