The best MIDI controller is the one that you have with you. Double Decker transforms an ordinary Bluetooth keyboard into a sophisticated MIDI controller, giving you a much bigger playing surface, while still being portable. The app is designed to work with US/English keyboards; the key arrangement for other languages may not be compatible.
On iOS, an app can only receive keystrokes from a QWERTY keyboard when it is in the foreground. For this reason, Double Decker must be in the foreground to work; this is a limitation of iOS, and there is no way that we can work around it. The app is designed to send MIDI notes to other apps (running in the background), or MIDI to apps running in the foreground on other devices.
The iOS operating system only makes key press information available to apps, and not key release. For this reason, Double Decker cannot make a QWERTY keyboard operate like a typical (piano) keyboard.
Press a key on the Bluetooth keyboard to trigger a note. When you touch another key, the first note is silenced as the next note is played.
Tapping the space bar will silence all sounding notes. While it would obviously be better if lifting up on a key silenced a note, iOS does not provide this functionality for app developers.
The app features a state-of-the-art Soundfont engine, advanced MIDI routing capability, support for Apollo MIDI over Bluetooth, and even Audiobus!
The keys are arranged with the two middle rows in a piano-style formation. Play a second instrument using the bottom row of keys, and two more instruments using the number keys and punctuation. Each key can be configured to trigger either a single note or a chord.
A second arrangement of the keyboard divides things into four grids, four-by-four each. This is great for finger drumming, and triggering samples and sequences.
Double Decker supports Soundfonts, opening up a world of different tones. The app also has full support for MIDI, giving almost unlimited sonic potential. Using the MIDI Learn feature in apps such as Loopy and Genome, you can start and stop recording, play synthesizers, and switch tracks, all with a Bluetooth keyboard.
If you have multiple iOS devices, you can link them together using the low latency connection provided by Apollo MIDI over Bluetooth. Run Double Decker in the foreground on one device to catch keystrokes, and then send MIDI to a second device, which can have a synthesizer or sequencer app in the foreground.
Key features of the app are the following:
* Innovative use of an external keyboard to trigger notes.
* Keyboard arranged into two groups, each with four different playing regions.
* Each region can be assigned a Soundfont patch, a set of MIDI destinations, or both.
* Soundfonts can be added using “open in” or iTunes file sharing.
* Each key in each region is configurable as either a note or a chord, with independent velocity control.
* Key configurations can be saved as presets, shared through email, or downloaded from the web.
* The app supports the Audiobus “input” slot.
* Built-in support as a Apollo MIDI over Bluetooth “A” endpoint.
Double Decker is available for $4.99