python - OpenCV cv2.VideoCapture(0) is not working well with webcam -

i trying use usb webcam computer vision project on raspberry pi outputs diminations of moving object. installed opencv , tried python code worked perfect on pc, when ran in raspberry pi b+ , output unexpected took video output cv2.imshow("video output", frame) see whats going on , saw thing strange. video flickering part red , part blue.

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although code worked perfect in pc maybe can help, here code:

import argparse import datetime import imutils import time import cv2 import numpy np  ap = argparse.argumentparser() ap.add_argument("-v", "--video", help="path video") ap.add_argument("-a", "--min-area", type=int, default = 200, help="min area") args=vars(ap.parse_args())  if args.get("video", none) none:     camera = cv2.videocapture(0)     camera.set(cv2.cv.cv_cap_prop_fps,2)     camera.set(cv2.cv.cv_cap_prop_frame_width,640)     camera.set(cv2.cv.cv_cap_prop_frame_height,480)     time.sleep(2.5) else:     camera = cv2.videocapture(args["video"])  while true:     (grabbed, frame) = camera.read()     if not grabbed:         break     frame = imutils.resize(frame, width=500)     cv2.imshow("testing",frame)     key = cv2.waitkey(1) & 0xff     if key == ord("q"):         break  camera.release() cv2.destroyallwindows() 

it turns out problem video source. webcam not compatible opencv although worked other computer video input package well