RjDj – Pure (Data) Love…

I’ve been enamored with the RjDj iPhone application after Corey mentioned it on the list. At first I was turned off by the developers talk about it being a “digital drug” but got hooked when the documentation indicated that it was Pd (pure data) ported to the iPhone.

At the risk of providing a terrible description, Pd is a (free) visual programming language, similar to Cycling ’74’s Max/MSP. I’ve had a heck of a time wrapping my head around the development environment…I’m used to writing out code, classes and such, but with these visual languages you create various objects on the canvas and wire them together. Anyway, RjDj has provided a reason for me to finally dive in.

The library that RjDj provides gives access to the iPhone’s accelerometer, touchscreen and microphone. Super cool. Also, the dev has provided a Pd patch to receive these inputs from the phone on a desktop computer – mainly for testing / debugging – but that could be a neat extended use for non-mobile applications.

So, I tried out the scene provided by the free version of RjDj and found myself humming and whistling while walking around Greenpoint…which sounded really interesting through the headphones, but then realized that everyone around me was staring because I was, well, humming and whistling to myself. Trippy, indeed.

Below is a quick video of the first scene I’ve written for RjDj. It’s based on the Echolon scene provided with the app, but uses accelerometer data to pitch shift the incoming sound. The pitch is low if the phone is stationary, but gets high when the phone is moved quickly. Fun.

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And here is the RjDj scene / Pd patch. If you want to try it on your computer you’ll have to substitute adc~ and dac~ for soundinput and soundoutput respectively. Also, unless you get accelerometer data the pitch shift will remain constant (although the echo will work fine).






2 responses to “RjDj – Pure (Data) Love…”

  1. nick Avatar

    this makes me wanna buy an iphone. i think that smile at the end really makes this video!

  2. Rutger Muller Avatar

    Nice article and thanks for the code. I will be making an RJDJ scene soon :).

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