Which FLOSS software for DIY CCTV / video surveillance ?

Hi,

I would like to build myself a DIY DVR

Here what I'm targeting

1. The software is FLOSS

2. Have a community/free/gratis version that can handle >= 16 cameras and it's usable (meaning not crazy restricted)
   or
   is paying, but not crazy scheme (like subscription etc..) So you pay once, and you can use that version forever for unlimited number of cameras.

3. Lightweight on resources ( can run on a Single-board computer )

4. Can handle Hardware compression.

5. Can handle Passthrough recording (IP camera)

6. Have a HTTP server User interface.

7. Can record audio, when the camera provide it.

8. Motion detection (possible to enable at certain times)

9. extra: Written in Python

10. can record in H265

Thanks.

If you have any reference or any good (recent) article I'm all ears :)