> these standards explicitly prohibited their use in implementing any open source implementation of the standards

Is that legally enforceable? IANAL, but that feels dubious to me. Feels like there should be a way around that.

If you make a thing and copyright it, you get to dictate terms. But the legal alternative would be a clean room implementation. The implementation team never saw the standard, so it's not being used.

Yeah, clean room implementation is the only way - and the route chosen by the aravis project that builds a FOSS implementation (which is a really great piece of software, way nicer to work with and easier to debug than the terrible vendor SDKs).

probably enforceable via patents.