Opencv python thread problems

I meet a problem that I can not get image from the USB camera when I use the threading method in Nano.
Here is my code using python:

import threading
import cv2
class T1(threading.Thread):  
    def __init__(self):
        threading.Thread.__init__(self)
    def run(self): 
        t1()
class T2(threading.Thread):  
    def __init__(self):
        threading.Thread.__init__(self)
    def run(self): 
        t2()
def t1():
    print('t1')
def t2():
    print('t2')
thread1 = T1()
thread2 = T2()
thread1.start()
thread2.start()
cap = cv2.VideoCapture(0)
while(1):
    ret, frame = cap.read()
    print('3')

It could not print 3 in Nano but it can print 3 in common PC platform.
What should I do ?

Hi,

Would you mind to share what kind of error did you meet?

Usually, we open camera with GStreamer pipeline which requires users to build OpenCV from source.
Here is a tutorial for your reference: https://jkjung-avt.github.io/opencv-on-nano/

Thanks.