Under Unix, there would be no way for those spaces to be passed to the process unless, as you said, they were explicitly quoted. The shell will interpret what is to be the delineation between arguments and just hand those arguments to the process that's run. Now, I don't know how that all would work under Windows (I imagine it would be the same, but who knows?), but, given the fact that LAME is developed under Unix machines and 99% of the ports out there are just cramming that same code into Windows, I doubt that that is actually the case.

But don't quote me on that. I could be wrong.