Proposal + request for feedback: navigator.enumUserMedia

Hi everyone,

I the course of playing around with navigator.getUserMedia, I bumped into
some limitations both on the spec and its implementation in browsers.
 TL;DR: I wanted to see what stands in the way to create a DAW (Digital
Audio Workstation) in the browser.

While I started with audio, this problem can be further generalized to
video as well. Here's a bunch of use cases that are difficult/impossible
with navigator.getUserMedia as it stands:

1) Populating a dropdown list with available audio inputs;
2) Switching between front and back cameras on a mobile phone;
3) Programmatically select a specific media source.

I've drafted an initial/incomplete spec + example usage, which can be read
at https://github.com/ruidlopes/enumUserMedia

Feedback & contributions are welcome!


Cheers,
Rui