My $0.02
Please recognize that real-time video encoding is VERY computationally demanding. A GPU with video encode/decode offload saves the CPU from having to do all the work (or needing a more powerful CPU). And laptops are more prone to thermal-throttling. So a dedicated circuit like NVENC will help. AMD has a reputation for poor software support, and especially in regards to H.264 encoding. Intel's latest GPUs are a bit of an unknown when it comes performance, especially with OBS. Personally, I'm curious to see what will happen with the new Alchemist GPUs and AV1 encoding.. but I won't be surprised if it takes a couple of years to mature to something where CDN start to switch over (and I'll be pleased if progress happens sooner).
OBS, being free, open-source software, isn't likely to be using proprietary/patented libraries for highly optimized encoding (like WebEx, Zoom, Teams, etc use). OBS provides lots of flexibility and power for a wide range of use cases. Personally, I don't expect OBS Studio project team to have a large budget and focus on optimizing for low-end hardware. Note: I'm just a fellow user, so I could be very wrong..
First, recognize the requirements of OBS (in the Help section) meaning some level of graphics support is required, but most modern x86 systems will meet that. So a basic laptop, with Intel CPU integrate GPU will likely suffice for lower resolution, low frate rate, lower overall CPU utilization (and yes, it means you may have to be careful... doable, but may require going beyond basic consumer understanding of how Operating System and OBS operate, and learn to optimize both... it depends..)
Unfortunately, the short answer is
- spend more money and lower risk of hardware resource contention (ie too demanding a workload for the computer)
OR
- with lower expectation on frame rate and resolution, time learning and/or money spent on others for optimizations at OS and OBS levels, then you should be able to get a lower-end system to work. [Why do I mention OS? MacOS and latest Windows OS learn towards functionality and eye-candy vs performance, so if Performance is you target you need to adjust default settings ... and lots of YouTube advice (and similar) is simply stupid/wrong. so not always easy for a newbie to determine most appropriate adjustments]
That said, if I read you post correctly, you are talking about 2 or 3 separate incoming video streams (I'm not sure if just laptop integrated webcam and USB webcam, or also something else??), and presuming you want to easily do Picture-in-Picture and swap between them means a computer capable of decoding all 2 (or 3) videos inputs simultaneously, and then encode for livestream. That is NOT a small ask
Could you get this to work on a really cheap lower-end consumer laptop? probably.. with time spent becoming technically proficient at multiple technologies. or paying consulting to help you out (cheaper to get more powerful laptop upfront, most likely). In my mind, it comes down to a clearer technical understanding of your requirements (a whole level deeper than you posted) and your budget/expectations, vs time availability and interest to pick up subject matter expertise in multiple tech areas (OS, OBS, etc).
Hopefully someone else will reply who has a similar need/requirement as you have and comment on performance requirements.
