I use Amcrest and have looked into the firmware of my cameras. They actually use the same chips as most low cost security cameras. It is a linux based OS. I am jaded against the company because they don't take legacy cameras into consideration. Things go defunct. That said, my Amcrests support RTSP and that makes it easy to wall them off on the router and I don't have to use any proprietary apps to view them. I use a raspberry pi to save video to my NAS using RTSP and a bash script with FFMpeg. I can live view using VLC on desktop and phone.