"RjDj" is a new iPhone application that mixes audio data from the iPhone's microphone in realtime and plays them back out your headphones to create an electronic musicish environment. Different "scenes" exist in lieu of proper songs, each of which use the open "Pd" descriptor language to define what to do with the sounds coming in through the microphone. Your voice might be remixed into a flanging loop in one scene; another might use increased volume to change the melody of a song.
It's easier to watch in the video than it is to explain — and even easier to understand if you just download it and play with it. I spent a couple of hours with my headphones in while working today and just let the environment integrate into the soundscape around me. It was hard not hum or whistle little tunes just to hear what they would do.
If you've ever consumed psychedelics, the auditory effects in some of the scenes are very similar to the time-slipping, inverse cascading repeats that can be provoked by some chemicals.
There are two versions: a $3 "Album" and a free "Single" with just one scene. I bought the "Album" and haven't felt at all ripped off, but the "Single" is a no-brainer download. I do hope there will be ways to add new scenes into the program without buying a whole different application.
I can't wait to see what else can be done with these sort of modern smartphone applications. (There's nothing RjDj does that couldn't be done on Android or any other OS, I think, sans the accelerometer interface.) Walking into different parts of town, tracked by GPS, might offer up a different set of samples, for instance. Someone could literally build an interactive, evolving soundtrack that emerges from the city as you walked around. You could add an ominous percussion track whenever two or more units were within close proximity.
Exclusive RjDj Interview: Interactive Music Listening, Everywhere You Go [CreateDigitalMusic.com]
RjDj Album [iTunes]
RjDj Single (Free) [iTunes]