Live streams in FastAPI

One person presents live to everyone watching: the picture, a chat beside it, reactions, and the count of who watches. The host goes live from the browser, a phone or OBS. Viewers may be signed in or not.

Who is who

Your server declares streams beside its rooms and calls, by pattern. The rule says who each person is in the stream:

# app.py: the show of the shop, show:mugs. Ann presents it, and everyone else watches and writes in its chat, signed in or not.
def show_role(user, p):
    if p["id"] != "mugs":
        return False
    return "host" if user == ANN else "viewer"

realtime.streams("show:{id}", show_role, reactions=True)

• The answer: False, "host" or "viewer", or a dict: role, info (what others see of them), chat (write or read), mod (keeps the chat), src and quality (what the host sends).
• A visitor who is not signed in comes with user None, and may only be a viewer.
• The settings of the stream, keyword arguments: reactions, people and chat (offline, links, fresh), each a value or a function of the parts of the name (live streams in depth).

The calls route (/api/realtime/calls) is already among the answers of wr.router(), for streams too.

The page

const calls = await rt.calls();
const show = await calls.stream( 'show:mugs' );

show.watch( document.querySelector( '#show video' ) );      // the picture and its sound
show.on( 'state', ( state ) => draw( state ) );            // idle, live, ended
show.on( 'viewers', ( n ) => ( count.textContent = `${ n } watching` ) );
show.on( 'message', ( m ) => addLine( m.from.name, m.text ) );
await show.chat.send( 'Hello!' );

if ( show.role === 'host' ) {
    await show.preview();    // the camera, shown in the same video
    await show.goLive();
}

The show card of the Example Shop does exactly this, in showCard() of its page.

More

Reactions, keeping the chat, OBS, and the refusals: live streams in depth.