Stream the screen of your Android device to a Chromecast using only free software!

.gitignore

.mypy_cache

README.md

aosp2chromecast

Stream the screen of your Android device to a Chromecast using only free software!

tl;dr: This is just glue code combining ScreenStream, pychromecast and DashCast.

What you'll need

1. an Android device (obviously)
2. the app ScreenStream installed on this device
3. a device with Python 3 installed - can be the same as your Android device (with eg. Termux) or your laptop or something
4. pychromecast and this script installed on this device
5. a Chromecast (obviously)
6. a single network where all these devices are placed in (and are able to see one another - Zeroconf)

What you'll need to do

1. open ScreenStream on your Android device
2. start this script with python3 aosp2chromecast.py - if you're running this on a different device, you'll need to pass --url <the URL ScreenStream is displaying>
3. press the play button in ScreenStream (you could have done this in the first step already)

More options are available (see -h), but this should be enough to get you started.

Be aware that your screen content is transmitted over the network without any encryption - only use this if you trust the network or don't have any sensitive content on your screen.

aosp2chromecast.py

#!/usr/bin/env python3

from argparse import ArgumentParser, Namespace
import socket
from time import sleep
from typing import List, Optional, Type, TypeVar
from urllib.parse import urljoin

import pychromecast
from pychromecast.controllers.dashcast import DashCastController

T = TypeVar("T")

def parse_args() -> Namespace:
    parser = ArgumentParser(description="stream the screen of your Android device to a Chromecast")
    parser.add_argument("--url", type=str, help="the URL ScreenStream is displaying (only needed when the app is running on a different device than this script)")  # TODO: type=url?
    parser.add_argument("--pin", type=int, help="the PIN ScreenStream is displaying (if you do not specify this, you will be asked for it)")
    parser.add_argument("--cast_name", type=str, help="the name of your Chromecast (if you do not specify this, you will be presented a list of available devices to select from)")
    # TODO: --cast_ip?
    args = parser.parse_args()
    return args


def ask(what: str, choose_from: Optional[List] = None, type: Type[T] = int) -> T:
    if choose_from is None:
        while True:
            inp = input(f"Please enter {what}: ")
            try:
                return type(inp)
            except ValueError:
                print(f"'{inp}' is not a valid {type.__name__}.")
    else:  # TODO: selection via arrow keys
        assert type == int
        print(f"Please select a {what} from the following options: (0-{len(choose_from)})")
        for idx, name in enumerate(choose_from):
            print(f"{idx}. {name}")
        while True:
            inp = input("> ")
            try:
                idx = int(inp)
            except ValueError:
                print(f"'{inp}' is not a valid int.")
            else:
                if 0 <= idx < len(choose_from):
                    return idx  # correct, but mypy didn't notice
                else:
                    print(f"'{inp}' is not in the range [0, {len(choose_from)-1}].")


def determine_url() -> str:
    # Try to find our primary IP address.
    # That is of course the one with which we would connect to Google.
    # Also, just do IPv4 here.
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.connect(("8.8.8.8", 1))  # This doesn't have to work.
    ip = sock.getsockname()[0]
    sock.close()
    # Just assume that ScreenStream listens on port 8080.
    return f"http://{ip}:8080/"


def find_chromecast(name: Optional[str] = None) -> pychromecast.Chromecast:
    casts = pychromecast.get_chromecasts()
    if name:
        for cc in casts:
            if name == cc.device.friendly_name:
                return cc
        else:
            print(f"Device {name} not found.")
    return casts[ask("Chromecast", [cc.device.friendly_name for cc in casts])]


if __name__ == "__main__":
    args = parse_args()
    
    pin = args.pin or ask("PIN", type=int)
    url_to_device = args.url or determine_url()
    url = urljoin(url_to_device, f"/?pin={pin}")
    cast = find_chromecast(args.cast_name)
    print(f"Going to open {url} on {cast.device.friendly_name}.")
    # TODO: Check whether this URL actually works.
    
    cast.wait()  # wait for connection
    dc = DashCastController()
    cast.register_handler(dc)
    dc.load_url(url)
    try:
        while True:
            sleep(1000)
    except KeyboardInterrupt:
        cast.quit_app()