i am unable to play video from file. the code is given as follows:

edit

 import cv2
cap = cv2.VideoCapture("m.avi")
while(cap.isOpened()):
    ret, frame = cap.read()
    print cap.grab()
    cv2.imshow('frame',frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()