how to enable h264 in peerconnection?

Question

many media says firefox support h264 in webrtc, but I can't find any information.

How to enable h264 in webrtc?

This is my mediaConstraints

var mediaConstraints = {
    video: {
        mandatory: {
           maxWidth: 640,
           maxHeight: 480
        }
    },
    audio: true
};

Answer 1

As of right now I tested on Firefox 36.0.4 and I can see h264 lines in the SDP. An Example of what I see that indicates the support for H264:

....
m=video 9 RTP/SAVPF 120 126 97
....
a=rtpmap:97 H264/90000
....

97 is the dynamic payload type, used here for H264. I hope it helps.