"Are you talking to me?"
Translation:Ĉu vi parolas al mi?
"Mi" is the indirect object so it's not in the accusative. Whenever there's a preposition before the object it's an indirect object, for example: to me, for whom, at her.
I hope this helps.
I think you can still substitute accusative to a preposition when context is clear enough, can't you?
I don't think you can in Esperanto; because that would be something like "Are you talking me?" It's the kind of thing that could probably happen naturally in a traditional language, but I think they try to avoid it in Esperanto.
Yeah, it's just that I'd read in an Esperanto textbook you could in certain cases, for example
mi restis dum du monatoj en Londono -- mi restis du monatojn en Londono,
mi iris al Parizo -- mi iris Parizon
li obeas al sia patro -- li obeas sian patron
But I get your point that it doesn't work with paroli al.
In the first examples you've listed, they aren't indirect objects, they're two more uses for the accusative - to indicate a period of time and to indicate direction. Indicating the direct object is only one of several uses we have for -n.
What are the differences in usage between «paroli» and «diri»? Specifically, would «diras» be appropriate in this sentence?
i think parolas is like speaking, whereas diras is saying. i speak(parolas) to you, i say (diras) hello.