...(http)
0xff 0xd8   --|
[jpeg data]   |--this part is extracted and decoded
0xff 0xd9   --|
...(http)
0xff 0xd8   --|
[jpeg data]   |--this part is extracted and decoded
0xff 0xd9   --|
...(http)

import cv2
cap = cv2.VideoCapture('http://localhost:8080/frame.mjpg')
 
while True:
 ret, frame = cap.read()
 print(frame)
 if ret == True:
  cv2.imshow('Video', frame)
 
  if cv2.waitKey(1) == 27:
   exit(0)

import cv2
import requests
import numpy as np
 
r = requests.get('http://192.168.1.xx/mjpeg.cgi', auth=('user', 'password'), stream=True)
if(r.status_code == 200):
  bytes = bytes()
  for chunk in r.iter_content(chunk_size=1024):
    bytes += chunk
    a = bytes.find(b'\xff\xd8')
    b = bytes.find(b'\xff\xd9')
    if a != -1 and b != -1:
      jpg = bytes[a:b+2]
      bytes = bytes[b+2:]
      i = cv2.imdecode(np.fromstring(jpg, dtype=np.uint8), cv2.IMREAD_COLOR)
      cv2.imshow('i', i)
      if cv2.waitKey(1) == 27:
        exit(0)
else:
  print("Received unexpected status code {}".format(r.status_code))