Most comments are in favour of the former, but we've been trained by every media player UI to understand that a button with a pause symbol means that the media is currently playing.
I think it's also worth noting that it is usually very obvious what state a media player is in, so it makes sense we would have different expectations from that UI vs one where we aren't sure of the current state.
It was easier to have "stop" be mechanics to disengage head, "play" to engage head" and "pause" being just on/off switch for the motor than trying to merge play/pause into 1.
> Most of us were trained to expect that before contemporary media players started showing up.
CD players started getting play/pause precisely because they didn't need to. Most VCRs also had digital controls (coz moving mechanisms via push of button would be harder with big tapes and heads) and they also did often have play/pause integrated.
Some opted for copying tape 1:1, some merged play/pause into one button, it certainly wasnt that all of them had separate pause.
Anecdotally (in UK&EU) every old tape, CD, or VCR player I ever had combined play and pause on a single button, even devices where there was no screen to show current state it was just the norm that the same button toggles the current state.
A media player can be in the "user wants to play" state and not be playing, because buffering is taking place. This is a very common state, yet all the media players I've seen have an ambiguous or confusing display during this state.
Except when it isn't playing. It get confusing/frustrating when dealing with low volume, buggy software like the Iphone Podcasts app or Bluetooth. Then you think, oh, maybe it's in a paused state.