Open Source
denoting software for which the original source code is made freely available and may be redistributed and modified.
Now look at the security industry and how it is run now. You think Avigilon is going to Open source their analytic's and other software that they sue every one else to use?
You think the Chicoms are going to let you engineer software that they cant control without a Government approval ?
You think all the VMS platforms that reap their income on yearly license fees are going to give that up that power for free?
It is in most cases a single function software: get the best quality images/video to a medium for later retrieval in case something happens. You are doing work on the hardware for used for video surveillance, you cannot game on the hardware for video surveillance, You can not check your twitter on a surveillance system.
There is also not enough Hardware diversity on the camera end for open source to be feasible. they are all made by the same handful of manufacturers for a whole host of name brand and knock off companies across the world.
Besides if you really wan to roll out own you can buy your Dev kits:
http://www.latticesemi.com/hdr60
https://www.ambarella.com/products/security-ip-cameras
https://www.leopardimaging.com/Thermal_IP_Camera_Dev_Ki.html
These companies regardless of what you think of them are paying for Development on these cameras, they have been paying on them for a while. When Dev Kits are as affordable and plentiful as Raspberry Pi kits (~$100) then you may see some open source Development come though otherwise I would dare say it will be same old same old till the Chicom's force all the other Manufacturers out of business.
Then you will have a whole new animal to deal with.