Turn your whistling into song with the tap of an app

Chordana Composer is a simple iOS app that can take snatches of melody and expand on them according to user preferences.

While the songs aren't exactly works of musical genius, the app is another example of how computers can emulate human creativity.

Designed for iPhone and iPad, Chordana Composer has a basic user interface with an abbreviated keyboard and simple editing tools. Users can input a melody by whistling, tapping the on-screen keyboard or manually entering the notes on a staff.

The next step is hitting the compose button, which lets you choose a genre (pop, dance, rock, jazz or world) and variables such as melodic tension. It then takes a few seconds for the app to produce a full song based on the melody, complete with sections such as introductions, verses and bridges. Chord changes appear above the notes on the staff as the song plays.

"Chordana Composer is the first app that lets users create a whole piece of original music from as little as a two-bar melody sung into the app, or as little as a one-bar melody when input via the app's on-screen keyboard," developer Junichi Minamitaka said after a demo in Tokyo this week.

While the auto-compose function only works with very brief melodies, the app can write relatively sophisticated jazz compositions, with dominant, suspended, seventh and ninth chords as well as walking basslines, solos and drum fills. The app can also link to MIDI synthesizers and the songs can be saved and shared.

Depending on the settings, the app-generated compositions can sound like a lot like a bland karaoke backing track or a generic thumping techno tune. But Composer can be a useful tool for songwriters struggling with a chord progression or an elusive bridge. It's also intriguing to hear how Casio's composition algorithms, which emulate structures used repeatedly in popular music, interpret the same melody in different genres.

Casio, which makes keyboards as well as watches and calculators, showed off another app at the demo. The recently released CZ app for iPad reproduces a vintage synth from 30 years ago, the Casio CZ-101. During the demo, a musician played a song on the actual keyboard while soloing on the app version, producing a convincing performance.

In addition to 36 waveforms from the CZ series of synths such as electric piano and jazz organ, the app has an envelope generator to modify tones, mixer functions and support for external MIDI instruments.

It isn't easy to play a melody on an iPad keyboard, let alone chords, but some musicians have welcomed app reincarnations of vintage synths including the Minimoog and the Korg MS-20.

The CZ app, however, has a unique feature called multiplay that not only allows up to four keyboards to be displayed so different tones can be played simultaneously, it can flip some of them so users on either side of the iPad can play together.

Chordana Composer and the CZ App for iPad are available on Apple's App Store for US$2.99 and $19.99 respectively.

Tim Hornyak covers Japan and emerging technologies for The IDG News Service. Follow Tim on Twitter at @robotopia.