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Air scratching: Let’s track turntable movement by affixing an iPhone to a vinyl record

Instead of using your iPhone and a specialized DJ app like Algoriddim’s djay for iPhone, clever minds have come up with a novel idea based on sensing a performer’s movement to alter the playback of digital audio in real-time. They call it Mopho DJ and it doesn’t require dedicated hardware or time-coded vinyl, explains Nick Brian, a researcher with the Center for Computer Research, Music and Acoustics at Stanford University. How does it work?

It’s based on an ordinary analog turntable which doubles as a physical interface to manipulate the playback of digital audio by placing an iPhone on a turntable. The handset is attached to a modified vinyl record in order to track turntable movement. The magic involves sensing a performer’s body movement via accelerometer and gyroscope sensors. This data is then applied to digitally scratch the recording in real-time. Other perks include real-time graphical display, multi-touch interaction and untethered performance. Oh yes, and they call it air-scratching.