         
         // 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;
        

        
        return nsString.substringWithRange(result!.rangeAtIndex(1))
    }
    
}