         
         // create a media stream and add audio and/or video tracks
         var mediaStream = peerConnectionFactory.mediaStreamWithLabel("ARDAMS")
-        mediaStream.addAudioTrack(peerConnectionFactory.audioTrackWithID("ARDAMSa0"))
+        
+        if self.config.streams.audio {
+            mediaStream.addAudioTrack(peerConnectionFactory.audioTrackWithID("ARDAMSa0"))
+        }
         
         self.peerConnection.addStream(mediaStream, constraints: self.constraints)
         

        }
        
        let origMLineParts = lines[mLineIndex].componentsSeparatedByString(" ")

        var newMLine: [String] = []
        var origPartIndex = 0;
        

            let mid: String = data?.objectForKey("id") as NSString
            let sdpLineIndex: Int = (data?.objectForKey("label") as NSNumber).integerValue
            let sdp: String = data?.objectForKey("candidate") as NSString
            
            let candidate = RTCICECandidate(
                mid: mid,
                index: sdpLineIndex,
