No videofile CV3.1+Python3+Ubuntu14.04

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I have problem with writing video to file. This small program:

import numpy as np
import cv2
import time

cap = cv2.VideoCapture(0)

time.sleep(0.1)

# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc('X','2','6','4')
out = cv2.VideoWriter('output.avi',fourcc, 25, (640,480))

while(cap.isOpened()):
    ret, frame = cap.read()
    if ret==True:

        out.write(frame)
        cv2.imshow('frame',frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    else:
        break

# Release everything if job is finished
cap.release()
out.release()
cv2.destroyAllWindows()

I see the frames in the window but no outputfile are generated. Nor any errors shown. What am I doing wrong?