Python aio webrtc stream desktop into web browser

Question

I trying to do an server side code in python that will stream desktop stream and audio via WebRTC aiortc. My server code:

import asyncio
import json
import os
import ssl

import aiohttp_cors
from aiohttp import web
from aiortc import MediaStreamTrack, RTCPeerConnection, RTCSessionDescription
from aiortc.contrib.media import MediaPlayer

ROOT = os.path.dirname(__file__)

pcs = set()

async def offer(request):
    params = await request.json()
    offer = RTCSessionDescription(sdp=params["sdp"], type=params["type"])

    pc = RTCPeerConnection()
    pcs.add(pc)

    # prepare local media
    player = MediaPlayer(os.path.join(ROOT, "audio.wav"))
    player1 = MediaPlayer(os.path.join(ROOT, "video.mp4"))

    @pc.on("datachannel")
    def on_datachannel(channel):
        @channel.on("message")
        def on_message(message):
            if isinstance(message, str) and message.startswith("ping"):
                channel.send("pong" + message[4:])

    @pc.on("iceconnectionstatechange")
    async def on_iceconnectionstatechange():
        if pc.iceConnectionState == "failed":
            await pc.close()
            pcs.discard(pc)

    @pc.on("track")
    def on_track(track):

        if track.kind == "audio":
            pc.addTrack(player.audio)
        elif track.kind == "video":
            pc.addTrack(player1.video)

    # handle offer
    await pc.setRemoteDescription(offer)

    # send answer
    answer = await pc.createAnswer()
    await pc.setLocalDescription(answer)

    return web.Response(
        content_type="application/json",
        text=json.dumps(
            {"sdp": pc.localDescription.sdp, "type": pc.localDescription.type}
        ),
    )

async def on_shutdown(app):
    # close peer connections
    coros = [pc.close() for pc in pcs]
    await asyncio.gather(*coros)
    pcs.clear()


if __name__ == "__main__":
    if False:
        ssl_context = ssl.SSLContext()
        ssl_context.load_cert_chain("cert_file", "key_file")
    else:
        ssl_context = None

    app = web.Application()
    app.on_shutdown.append(on_shutdown)
    app.router.add_post("/offer", offer)

    cors = aiohttp_cors.setup(app, defaults={
    "*": aiohttp_cors.ResourceOptions(
            allow_credentials=True,
            expose_headers="*",
            allow_headers="*"
        )
    })

    for route in list(app.router.routes()):
        cors.add(route)

    web.run_app(
        app, access_log=None, host="0.0.0.0", port=8080, ssl_context=ssl_context
    )

In this code I have two files video and audio file that the server streams. But how I can implement desktop stream video and audio

I tried only load files and stream them and I expecting that the code will stream desktop video and desktop audio in real-time.