Using Python and Raspberry and nobile network for live webcam streaming wihtout bigger lags?

Question

is it possible to write in python a webcam stream script for mobile networks. The biggest requirement is that it shall be realtime as possible without bigger lags and delay. I have tried some standard examples I found on google via UDP. While beeing in my private Wifi it works perfect for a 320x240 resolution.

But as soon I switch to my LTE Surfstick where I have a about 3-4 Mbits of upload, the picture is lagging extremly. It has a big delay and lot of frame drops.

I wonder why, because 3 Mbits should be enough...

So my guess is that I need some kind of compresssion? Or I'm missing something essential here and its even not possible without buffering a lot, which would make realtime impossible?

Here is the code i use vor the raspberry:

import socket
import cv2 as cv


addr = ('myserver.xx', 1331)
buf = 512
width = 320
height = 240
cap = cv.VideoCapture(0)
cap.set(3, width)
cap.set(4, height)
cap.set(cv.CAP_PROP_FPS, 25)
cap.set(cv.CAP_PROP_FOURCC, cv.VideoWriter.fourcc('M','J','P','G'))

code = 'start'
code = ('start' + (buf - len(code)) * 'a').encode('utf-8')


if __name__ == '__main__':
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    while(cap.isOpened()):
        ret, frame = cap.read()
        #frame = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
        if ret:
            s.sendto(code, addr)
            data = frame.tostring()
            for i in range(0, len(data), buf):
                s.sendto(data[i:i+buf], addr)
            # cv.imshow('send', frame)
            # if cv.waitKey(1) & 0xFF == ord('q'):
                # break
        else:
            break
    # s.close()
    # cap.release()
    # cv.destroyAllWindows()