RTCMultiConnection & Mute/UnMute

// if local or remote stream is muted 
connection.onmute = function(e) { 
    e.mediaElement.setAttribute('poster', '//www.webrtc-experiment.com/images/muted.png'); 
};

// if local or remote stream is unmuted 
connection.onunmute = function(e) { 
     e.mediaElement.removeAttribute('poster'); 
};