Hello Richard,
have a look at rtl_tcp.
You would need users to run rtl_tcp and then you should
be able to get the data from the network with your own
proprietary software.
I have no experience with rtl_tcp, but it it would not
do precisely what you want you can modify it and make
your modified version available with an opensource license.
As I understand things: Once the data is on your local
network it has left the world of open source and you
should be free to process it whatever way you want.
Regards
Leif
If I write software that uses the rtlsdr library that
is already installed
on the computer, does my software also have to be opensource?
Thanks,
Richard