Receive video stream into Rails 7 via websocket

Question

I have a very simple nodejs application that receives a video stream and shows it in a player.

Here´s the part of the code that listens, receives the video stream and sends it to the player.

app.set('port', 3000);
app.set('ipaddr', '127.0.0.1');

var http_server = app.listen(app.get('port'), app.get('ipaddr'), function() {
  console.log('Express server listening on port ' + http_server.address().port);
});

var ws = new WebSocket.Server({server: http_server, perMessageDeflate: false});

app.post('/', function (req, res) {
    req.on('data', function(data) {
        ws.broadcast(data);
    });
});

ws.broadcast = function(data) {
    ws.clients.forEach(function each(client) {
        if (client.readyState === WebSocket.OPEN) {
            client.send(data);
        }
    });
};

I use JSMpeg to display the video.

var stream_url = 'ws://127.0.0.1:3000/'
var player = new JSMpeg.Player(stream_url, {canvas: $("#canvas_id"), videoBufferSize: 1024*1024});

Currently I´m sending the video from the camera using a Python script on my Mac like this:

output = Popen("ffmpeg -f avfoundation -framerate 20 -video_size 640x480 -pix_fmt uyvy422 -i '0' -f mpegts -codec:v mpeg1video -s 640x480 -b:v 1000k -bf 0 -", stdout=PIPE, stderr=sys.stdout, shell=True)
res = requests.post('127.0.0.1:3000', data=output.stdout, stream=True)

This is working, the video is posted to the nodejs app and the player shows it.

BUT I want to do the same with a Rails 7 application.

I have checked some tutorials to find out about action cable and so, which is new for me. And I have created a POST route to receive the stream from the Python script, but it is not receiving anything. Or it is not receiving the data correctly with:

requests.post('127.0.0.1:3000', data=output.stdout, stream=True)

Because if I try:

requests.post('127.0.0.1:3000', data="SOMETHING", stream=True)

I can see in the Rails app logs:

{"SOMETHING"=>nil, "controller"=>"home", "action"=>"input"}

Any hints to get what I have working with a simple nodejs app with a Rails 7 app?

UPDATE 1

Maybe my question should be simplified and reformulated...

With JSMpeg you can receive a video stream in this way:

var player = new JSMpeg.Player(stream_url, {canvas: $("#canvas_id"), videoBufferSize: 1024*1024});

So the question should be:

How can you create such endpoint, the stream_url, with Rails 7?