How to choose input video device for webrtc?

Question

I am studying webRTC application.

My reference is this software

apprtc https://code.google.com/p/webrtc/source/browse/trunk/samples/js/apprtc/

demo https://apprtc.appspot.com/

My computer has bult-in video device and apprtc uses this video device . However I want to use USB-video camera instead.

I am searching the way to change input video devices. But I couldn't find any clue in source files.

does anyone has information?

Answer 1

On Chrome:

chrome://settings/content/camera chrome://settings/content/microphone 

On Firefox: media.navigator.permission.disabled=false