You are currently browsing the category archive for the ‘Code & Development’ category.

Oh wow…talk about a throwback. I just discovered this video of me at the first ReCon in 2005 talking about IDS and Security Data Visualization Theory and Practice. It’s all still completely valid.  Enjoy!!!

Per previous posts, I am making some free software available here (although it’s somewhat niche): A Mac OS X Distributed Objects server for the Neurosky brain wave reading Mindset and a Quartz Composer plug-in client for the server. (If you have neither OS X nor the Mindset, you might want to wait for a future post where I talk more about how the brain wave art project is coming.)

This post will also serve as a brief introduction to what it would take for you to write your own Cocoa client for the server. But, If you just want the software, you can get it here:


  • To install the client for Quartz Composer, close QC and copy the .plugin file to: “/Library/Graphics/Quartz Composer Plugins”. When you next open QC, you should find it in your Patch Library listed as “MindSetQCClient”.  Usage of the patch should be obvious,
  • The server shouldn’t need to start first as long as the client periodically checks for a vended object, but when troubleshooting it’s probably a good idea to start the server, then the client.
  • The server needs the Thinkgear bundle in same directory as the server app. (I’m not including the Thinkgear bundle, it’s available from the Neurosky website for free as part of their developer stuff.
  • Neurosky documentation has instructions for how to figure out what serial port your mindset is on, iirc.  The default for the server is the one I use.
  • I’ve borrowed so heavily from a hodge-podge of tutorials and examples, that I’m not going to include a license for the code. Use it as you will.


So, onward to the tutorial/implementation details:


Distributed Object Mindset Server and Client

This server is intended to be a little easier to use than some of the connection methods Neurosky provides (at least in my mind). It grabs data from the Mindset and provides it to Cocoa client applications (such as my Quartz Composer plug-in) by using Objective-C / Cocoa’s Distributed Objects interprocess messaging capability.

To access the Mindset data, the client must create an NSConnection to “JacksMindsetServer”. This gives it access to a vended object which supports the following very simple protocol (this protocol will have to be included in your client header file):

@protocol PassingMindData

-(int) getDataCount;

-(NSArray *)getOldestData;



Creating the connection to the vended object which uses that protocol is simple and requires only a short bit of code:

if (!sharedObject)


NSString *_host = nil;

sharedObject = (id <PassingMindData>)[[NSConnection rootProxyForConnectionWithRegisteredName:@”JacksMindsetServer” host:_host] retain];


You should now have an object called “sharedObject” which allows all of the methods specified by the “PassingMindData” protocol created above and which will pass the data from the mindset server to your code. To do so, the primary method is “getOldestData”. Calling this method will return an array of the oldest line of values from the Mindset and getDataCount returns the number of lines currently queued.

The returned array contains ordered NSNumbers representing each type of value available from the mindset. The array elements can always be accessed in the following order:

  • Attention (0)
  • Meditation (1)
  • Raw (2)
  • Delta (3)
  • Theta (4)
  • Alpha1 (5)
  • Alpha2 (6)
  • Beta1 (7)
  • Beta2 (8)
  • Gamma (9)
  • Gamma2 (10)
  • SignalQuality (11)

The client is left to access these elements as it pleases from the NSArray object returned by getOldestData. The server also relies on the client to remove the original data from the server as soon as it grabs it by calling “removeOldestData” on “sharedObject”.  (If the client does not call this, there is no auto-cleanup by the server until it’s stopped or exits and the client will not be able to access new data.)

If multiple lines of data are queued, getOldestData and removeOldestData should be executed repeatedly. A simple example would be:

if ([sharedObject getDataCount] > 0)


mindDataLine = [NSArray arrayWithArray:[sharedObject getOldestData]];

[self setOutputAttention:[[mindDataLine objectAtIndex:0] doubleValue]];

[sharedObject removeOldestData];


That’s really it.  How to write a server is out of the scope of this post, but Neurosky has some great documentation and have provided examples from which I have –heavily–  borrowed.

Let me know if you have questions or need further explanation. I’m going to continue to work on the art project with this stuff and will post more about that later.

Longer, more detailed post to follow – with free code and everything – but I wanted to post a video of art being made with my brainwaves:

In this demo (which is a significant step further than my last), my project selects between a series of images, merges them, moves them, and adds various visual effects based only on input from my brain waves (as measured by a Neurosky Mindset). All images – both drawings and photos – were made by me.  Depending on when I run this, the images selected and how they’re merged vary significantly. In this case, only a small subset were selected. Other times, there is a wider variety. It’s important to note that often, this has created pairings and mergings that are fantastically cool looking.  The Next step, creating a self portrait video of me sleeping with a curved screen over top of me projecting what my mind does with this while I sleep.

All –

I finally decided to put the Xcode project and associated source for pkviz up for free download and license it under GPL v3.

I’ve created a google code page for it HERE.

You can grab a stand alone zip of the source/project HERE.

(I’ve never used SVN before, so what’s up at the google code page might periodically be fubared, so you might want to start with the zip)

Feel free to download, comment, and please -contribute-. This was my first Objective-C app and first Xcode project, so if it’s a mess…well…deal or help? :)

Just remember the google code page if you want to post some updates or questions.

I’ve also made some haphazard notes to help people understand the code:


The aquireData class handles reading the tcpdump text file. It uses Core Data to store the data. If I had to do it over, I wouldn’t have used Core Data…but it is what it is.  You can find the data model by double-clicking pkviz_DataModel under the Models folder in the project in Xcode.

pkGraphView is a subclass of NSView that I use to handle the layers, which are done in Core Animation (easy enough to understand). The view has a delegate function (drawLayer) which I handle in the layerDelegate class to deal with drawing the paths for each layer.

Everything else is handled by transformData – it’s pretty much my controller.

Rough flow:

the Load button tells aquireData to parse tcpdump and store in a core data context

The launch button kicks off transform data, which pulls in the data from the core data context, sticks it into an array, launches a thread to pop out individual packets, and then tells the view when it’s read to display another packet.  Everything else stops, starts, adjusts the current packet referenced, or aids this animation loop process.

The main array of packets in transformData is bytepakposSet.  It is an array of packet arrays. packet arrays contain arrays of bytes with 2 values in them: bytevalue, and byteposition

so, if you wanted to access the third packet in bytepakposSet and see what the byte value of the first byte stored is, you’d do:

[[[[bytepakposSet objectAtIndex:2] objectAtIndex:0] objectAtIndex:0] intValue];

if you wanted to get the byte value and position returned in an array:

[[bytepakposSet objectAtIndex:2] objectAtIndex:0]

Core Data doesnt return objects in order, so you dont know ahead of time what order the bytes are in the packet, youll have to sort them by position in packet first. You can find position:

[[[[bytepakposSet objectAtIndex:2] objectAtIndex:0] objectAtIndex:1] intValue];

Follow me on Twitter

My Art / Misc. Photo Stream

phoenixhike - 4

phoenixhike - 3

phoenixhike - 2

phoenixhike - 1

phoenixhike - 7

More Photos