Python 3 streaming video using requests: where is the loop?

Question

Varun Chatterji posted how to use requests to stream video from an IP (ethernet) camera that requires a login and password. This is exactly what I needed and the only thing that works for my camera in python 3.4 on windows 7.

However, where is the loop in his code? When I run this code it runs infinitely while showing video in a cv2 window. However, the code lacks a "while True:" statement and I'm not finding any help in my searches. I'd like to move the loop to higher level module, but I don't know where the loop is.

Said another way, can someone refactor this code so there there is a "while True:" line somewhere? That would let me see what is inside the loop and what is not. I'm finding the requests documentation very hard to follow.

Varun's code for reference:

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))

The motivation for this is that I want to move the stuff "inside the loop" into a subroutine, call it ProcessOneVideoFrame() and then be able to put into a larger program:

while True:
    ProcessOneVideoFrame()       
    CheckForInput()
    DoOtherStuff()
    ...

Answer 1

However, where is the loop in his code?

At this line:

for chunk in r.iter_content(chunk_size=1024):

iter_content is a generator which makes for looping until the stream is empty.

Some doc here: http://docs.python-requests.org/en/latest/api/#requests.Response.iter_content