If you're modifying the picture at all, outside of what some single-purpose hardware in the phone might already be made to do, then it's probably best to not stream directly from the phone anymore, but to use the phone as a camera for OBS. Then OBS does whatever you need, and streams the result from there.
It might even use the same phone's hotspot for the internet connection, but be aware that cell networks are usually not reliable for streaming. Though if you can get the same encoding settings in OBS as what the phone uses, it shouldn't be any worse.
However!
Laptops are bad at this! Their specs only last a few minutes before they overheat and slow down. That kills the stream.
- If you can possibly use a desktop tower, DO!! Put it on a cart, build it into an existing rig, whatever you have to do to make a desktop streaming machine mobile.
- If you MUST use a laptop, look at the "Mobile Workstation" class of machines. They're thick and heavy, and somewhat expensive because there's not as much of a market for an ACTUAL COOLING SYSTEM that can keep up with a *continuous* load like live media production needs. I have one, from 2015, and it does just fine today. Mid 4-figures new. I would not expect "just any laptop" to do that, even if it were new today.
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To pedantically answer your question:
...without usb connection to the mobile phone...
there are several phone apps that stream the camera over WiFi. I like this one:
Turn your phone into a wireless camera!
play.google.com
No internet required at all, after installation of course, so you can set it up in the boonies and at least do "live to tape". It has ads, but only on the phone itself, never on the stream, and it doesn't disable itself if it can't get internet to retrieve the ads.
Set it up and start the server (don't forget that part!), then point a browser to it, and there it is! OBS's browser works just as well as any other, so now you have that camera in OBS.
(if you do forget to start the server, and so you don't get a picture, you'll need to refresh the browser after you correct the mistake - it does not auto-connect)
If you really must stream on a cell network, then you can use the same phone as a hotspot, as mentioned above. Raw camera goes over WiFi to OBS, and the finished stream goes back over WiFi to the same phone and up to the cell tower. But again as above, I would not rely on that unless I absolutely had to. Use a wired internet connection if at all possible: wired all the way, and not just to an "island" that itself connects over WiFi to something else.
