To get good quality at a low file size, you would need to do a lot of compression which uses a ton of CPU. And when you re encode you will lose the compression anyway.
These settings are great but they do have a large file size.
https://obsproject.com/forum/resour...lity-recording-and-multiple-audio-tracks.221/
If you use NVENC on VBR around 50000 for 1080p60 you should have fairly good quality. (that would be like 7.5 GB for 20 min) If you go for 720p30 and use VBR of around 25000 which would be about 4 GB for 20 min.
You wont be able to get better quality at a lower file size on a PC like that.
To get the file size you want you would need a bitrate of around 1000 which would give terrible quality at HD resolution even if you were to record extremely compressed (even on a top of the line CPU).
Why do you need such low file sizes anyway?
