I have been looking for ages for a camera that I could install at my front door and that would fit all my requirements, and finally I found one that does. It is very open source friendly, and the manufacturers are very responsive if you need any help or if you have any request.
The doorbell cam works with an app which allows you to see and talk to the person in front of your door. But in addition, you can record all video directly to your nas, you can use the domoticz camera function to get a picture of the person in front of your door, and the doorbell chime works via 433mhz, so you can receive this signal via your rfxcom (I needed custom firmware for this, but also the manufacturer of RFXCOM is very helpfull).
Just to be clear, I dont have any stocks or something in this company. Just a happy customer that found a product that others might enjoy as well
https://www.dbell.ca/
Domoticz cam settings
IP address : IP camera IP Address (e.g. 192.168.1.11)
Port : 81
Username : empty
Password : empty
ImageURL : /snapshot.cgi?loginuse=<IP cam Username>&loginpas=<IP cam Password>