Extract nth frames from video file using Python 3.6.1 and OpenCV

main.py

import os
import errno
import cv2

def extractFrames(videoFile, pathOut):
  # Create output directory:
    try:
        os.mkdir(pathOut)
    except OSError as exc:
        if exc.errno is not errno.EEXIST:
            raise
        pass

  # Open video file, create nth-frame counter at first frame (0), set video read to that frame, and read frame:
    cap = cv2.VideoCapture(videoFile)
    count = 0
    cap.set(1, count)
    ret, frame = cap.read()

  # Loop nth-frame counter until end of video file:
    while ret:
      # Console output for debugging:
        print('Read %d frame: ' % count, ret)
        
      # Write nth frame to file (frame_N_.jpg)
        cv2.imwrite(os.path.join(pathOut, "frame{:d}.jpg".format(count)), frame)
        
      # Set capture interval.  E.g. with a video at 30fps, count += 30 captures frames at 1-second intervals
        count += 30
        cap.set(1, count)
        ret, frame = cap.read()

  # End of loop; close video file; close image windows (which I didn't open, here):
    cap.release()
    cv2.destroyAllWindows()

def main():
  # Call frame-extraction method with filename and directory parameters:
    extractFrames('hw2.1.avi',
                  'Macro_temp')

if __name__=='__main__':
    main()