cap = cv2.VideoCapture(video)
width  = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))


B = None

T =  10
while(cap.isOpened()):
    ret, frame = cap.read()
    if not ret:
        break

    I = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    I = I.astype(np.float32)
    I = cv2.GaussianBlur(I, (3, 3), 0)

    # initialisation avec la première frame
    if B is None:
        B = I.copy()

    # mise à jour du fond
    actifs =np.abs(I-B)>=T
    diff = (actifs)*255
    maj = B < I
    B[maj] +=1
    B[~maj] -= 1

    imshows([I,diff])

    if cv2.waitKey(10) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()