To get an alternative video input from MediaDevices.getUserMedia, my understanding is that you need to pass in the deviceID as a constraint. But, in Safari, to get access to deviceIDs via enumerateDevices, I need to call getUserMedia and get permission from the browser first (maybe there's another way?). The problem is that this initial getUserMedia call only returns device info for devices I've given permission for, so I still don't have the deviceID of the alternative video input.
How can I get the deviceID for this video input?
In my case, I'm trying to find the deviceID for Snapchat's "Snap Camera". In Chrome, I'm able to find and stream this video input.