eyescope program that crashes after 1 minute or so

# import the necessary packages
from imutils.video import VideoStream
from numpy import *
import datetime
import argparse
import imutils
import time
import cv2

def improc (src):
  p0 = cv2.cvtColor( src, cv2.COLOR_BGR2GRAY )
  p1 = cv2.blur( p0, (7,7) )
  cv2.equalizeHist( p1, p0 )
  return p0

def cpBigframe (i, frame):
  bigframe[ :, i*wd:(i+1)*wd] = frame[:,:]
  return

vs =  VideoStream(0).start()

# def parameters and init
ht,wd=360,480 # 600/400
#bigframe = zeros( (300, 800, 3), uint8 ) #[0:600, 0:400]
#bigframe = zeros( (ht, wd*2), uint8 ) #[0:600, 0:400]
bigframe = zeros( (ht, wd*3), uint8 ) #[0:600, 0:400]
template1 = template2 = zeros( (ht, wd), uint8 ) #[0:600, 0:400]

# loop over the frames from the video stream
tick = 0
while True:

  time.sleep(0.03)

  # grab the frame from the threaded video stream and resize it
  # to have a maximum width of 400 pixels

  try:
    frame = vs.read()
    frame = imutils.resize(frame, width=wd)
    cv2.imshow("Eye Scope", frame)

    processed = improc( frame ) # from color to b&w

    cpBigframe(0, processed)
    cpBigframe(1, template1)
    cpBigframe(2, template2)

    # draw the timestamp on the frame
    timestamp = datetime.datetime.now()
    ts = timestamp.strftime("%Y-%m-%d %a %H:%M:%S")
    cv2.putText(bigframe, ts, (10, bigframe.shape[0] - 10), cv2.FONT_HERSHEY_SIMPLEX,
      0.35, (0, 0, 255), 1)

    # show the frame
    cv2.imshow("Processed", bigframe)

    key = cv2.waitKey(1) & 0xFF

    if key == ord("1"):
      template1 = processed
    if key == ord("2"):
      template2 = processed

    # if the `q` key was pressed, break from the loop
    if key == ord("q"):
      break

  finally:
    """
    if ( tick ):
      tick = False
      print ( "\r-", end="", flush=True )
    else:
      tick = True
      print ( "\r|", end="", flush=True )
    """


# do a bit of cleanup
cv2.destroyAllWindows()
vs.stop()