>No, because that is not a requirement of ours. I'm fully confident I could do all that with free software should I have the motivation and requirement to do so.
I can offer you $2000 (it's about the breakeven price for this task) for a solution that can utilize hardware not more expensive than in Windows, with similar features. It also should be done within a couple of weeks.
I have really checked it and there's nothing available for Linux - the only project is Zoneminder and it has extremely poor hardware support.
That's one typical task in Linux migration in the real world out there. And I have encountered tons of problems like that.