Polyplayground for iPad has a synthesizer built in, with separate pitch bend for each finger, but is designed to be used as a MIDI controller via Camera Kit and MIDI interface. For live performance, the app takes MIDI input, allowing you to visualize what a jam partner is playing. You can also stream chords you have already played into the device so that you are never lost if you want to improvise.
This app is great for the producer, composer, music theorist, and student. It makes understanding music theory easier, because the spaces are ISOMORPHIC. This means that chords are the same in all keys. One only needs to learn a chord shape once to use it in any key.
You can press the Horizontal/Vertical buttons to change your pitch space.
Guitar/bass players can change the pitch space to 5:1 (fourths by chromatic) for their familiar layout, while cello players can use 7:1 (fifths by chromatic).
Other notable spaces are 4:7 (Longuet Higgins) and Gerald Balzano’s 4:3. In 4:7, a square is a major 7th. You can move this square one step at a time to the left to do a very John Coltrane like progression: transposing a major 7th down by major 3rds.
MIDI input allows one to visualize existing music in this space to understand it easier. One can jam along with another musician, or existing MIDI chords and never get lost- because you can see what is going on.
It also works wirelessly via OSC to allow for music theory lessons to be taught remotely, or notes to be sent across the stage.
Virtual MIDI is supported so you can now use Polyplayground to control other instruments on the same device.