German startup Algoriddim today announced the launch of Djay 2 for iOS, a completely re-engineered version of its immensely popular DJ app. Its most impressive feature, HD Waveform, analyzes every song in your library and color codes important parts of each song so it's simple to hop between chorus and verse as you're mixing. As with with Traktor DJ for iOS, you can drag, scratch, and tap on the waveforms for different effects. If you look closely, you'll notice that the actual waveforms are mapped onto the surface of the vinyl as well. "Skeuomorphism can be a design element — here it provides a tangible benefit," says Algoriddim CEO Karim Morsy.

Djay, which has been the top-selling music app in most countries (aside from Apple's GarageBand) since it launched, has come a long way. What was once freeware for the average DJ back in 2006 has now been used by Prodigy to play shows in front of 50,000 people, and Algoriddim's engineering reflects that. The HD Waveform functionality, for example, was built to help anyone see the exact point in "Evacuate The Dance Floor" by Cascada where Eminem starts rapping.

Other new features include a sampler that lets you record samples of the track you're currently spinning, slip mode (for scratching without interrupting your track), and slice mode — which cuts up tracks into tiny chunks so you can tap to replay a moment in a song over and over again. "Slice mode turns the song into a drum machine," says Morsy, as he taps on his iPad and re-orders the opening bloops of "Kids" by MGMT.

While Djay isn't built for Tiesto and Avicii, Morsy increasingly finds himself bowing to the will of professionals asking for certain features. "All the pros were yelling at us about being in the club and pestering their eyes with our bright Library screen," he says, "So, we added Night Mode."