Hi and thanks for the PR!

What should happen when a RCS user attempts to start recording with no streams selected?

1. Returns an error message
2. Selects all streams (preserves prior behavior) and records

Thanks for the quick reply @cboulay ,

I would go for an error message.

I speak for my specific use of the software that may run on a university network where other amplifiers and HMD devices can pop on anytime and disrupt measurements.

I would be ok with a select all being triggered after the gui/cli opens, to preserve a little bit of consistency with prior work.
The way it was designed: start = select all + start it left no choice for a rcs client to actually pick the desired streams, not even after transmitting a config file or using select none. Also I added select <str_search> and regexselect <str_pattern> for covering the missing functionnality.

@lokinou , there really isn't a perfect solution because preserving existing behaviour is also contrary to how the (much more commonly used) GUI works. if we're going to change default behaviour then we might as well align with the GUI. So, I'd be OK with leaving the streams unselected at startup (unless specified by config file) then raising an error if trying to record without any streams selected. (Selected and not-yet-available should be allowed).

Would you be willing to modify your PR in that way?

Linking to #83