In order to retrieve the list of possible microphone/camera sources to select from, you can use the MediaStreamTrack.getSources function after which you can set the selected camera id as a "sourceId" constraint on getUserMedia.
Please refer to our demo and source code for a working example
Note : The above sample uses Temasys's version of AdapterJS, a polyfill that wraps around each browser and provides a standard API to use. We recommend using the latest version of the Temasys WebRTC plugin with the latest version of AdapterJS.
Other Articles you may be interested in
Why are my Users not prompted to select a Media Input device?