example of auto sorting devices by serial no:

gistfile1.txt

//---------------------------------------------------------------------------
bool ofxKinectContext::init() {
    if(freenect_init(&kinectContext, NULL) < 0) {
        ofLog(OF_LOG_ERROR, "ofxKinect: freenect_init failed");
        return false;
    }
	
	//NEW:
	freenect_device_attributes * devAttrib; 
	int numDevices = freenect_list_device_attributes(kinectContext, &devAttrib);

	int id = 0;
	devicesList.clear();
	for(int i = 0; i < numDevices; i++){
		indexPair dl;
		dl.id = id;
		dl.serial = devAttrib->camera_serial; 
		devicesList.push_back( dl );
		id++;
		devAttrib = devAttrib->next;
	}
	
	freenect_free_device_attributes(devAttrib);
	
	cout << "numDevices is " << numDevices << endl;
	cout << "order is: " << endl; 	
	for(int i = 0; i < devicesList.size(); i++){
		cout << "["<<devicesList[i].id<<"] " << devicesList[i].serial <<endl;
	}
	
	sort( devicesList.begin(), devicesList.end(), sortIndex); 
	
	cout << "order is now: " << endl; 
	for(int i = 0; i < devicesList.size(); i++){
		cout << "["<<devicesList[i].id<<"] " << devicesList[i].serial <<endl;
	}	
	
    ofLog(OF_LOG_VERBOSE, "ofxKinect: Context inited");
    return true;
}


bool ofxKinectContext::open(ofxKinect& kinect, int id) {

    if(numConnected() >= numTotal()) {
        ofLog(OF_LOG_WARNING, "ofxKinect Cannot open any more devices");
        return false;
    }
    
	//NEW:
	if( id < devicesList.size() ){
		id = devicesList[id].id; 
	}
	
.....




//NEW:
class indexPair{
	public:
		string serial;
		int id;
};


/// \class ofxKinect
///
/// wrapper for the freenect context
///
/// do not use this directly
///
class ofxKinectContext {

    public:
        
        ofxKinectContext();
        ~ofxKinectContext();
        
        /// \section Main
        
        /// init the freenect context
        bool init();
        
        /// clear the freenect context
        /// closes all currently connected devices
        void clear();
        
        /// is the context inited?
        bool isInited();
        
        /// open a kinect device
        /// an id of -1 will open the first available
        bool open(ofxKinect& kinect, int id=-1);
        
        /// close a kinect device
        void close(ofxKinect& kinect);
        
        /// closes all currently connected kinects
        void closeAll();
        
        /// \section Util
        
        /// get the total number of devices
        int numTotal();
        
        /// get the number of available devices (not connected)
        int numAvailable();
        
        /// get the number of currently connected devices
        int numConnected();
        
        /// get the device id of a kinect object
        /// returns index or -1 if not connected
        int getId(ofxKinect& kinect);
        
        /// get the kinect object from a device pointer
        /// returns NULL if not found
        ofxKinect* getKinect(freenect_device* dev);
        
        /// is the an id already connected?
        bool isConnected(int id);
        
        /// get the id of the next available device,
        /// returns -1 if nothing found
        int nextAvailableId();
        
        /// get the raw pointer
        freenect_context* getContext() {return kinectContext;}
        
    private:

	//NEW: 
        vector <indexPair> devicesList;

        freenect_context *	kinectContext;  // kinect context handle
        std::map<int,ofxKinect*> kinects;   // the connected kinects
};