Pulseaudio Audio Stream Info

Hi all, I’m considering writing an extension that would expose an mpris api for video and audio elements. The functionality I want to implement it to allow a user to play/pause videos and to click on something outside the browser to activate the window and switch to the tab. Most of this I think should be doable, but one part I really want is some way of knowing which pulseaudio stream belongs to with video element. The reason being that an application might want to show a volume control for a stream that doesn’t implement mpris, while hiding it when it does.

Does anybody know of any API that would allow one to add metadata to a pulse audio stream, or even just read info so I could put it into the mpris metadata?

I know this is a kinda odd request, so I really appreciate any help/advice people can give.