Music Toys

The plan named aubio and Essentia, the standard open-source audio libraries. Both are GPL-licensed, which doesn't sit well with a closed-source app on the stores.

So we wrote three detection engines in pure Dart, one each for tempo, key and pitch, and released them under the MIT licence. Heavy analysis runs off the UI thread; when three parallel jobs copied roughly 90 MB of audio and froze Android, we folded them into a single background worker.

The classic tempo mistake is landing on half or double the real speed. Instead of hiding that, the result card always shows the half and double values and the top candidates, one tap from being chosen.

A second pipeline handles melodic material like piano and vocals. If both come up empty, the app sends you to Manual mode to mark beats on the waveform instead of showing a dead-end error.

A tuner that's accurate but twitchy is useless on a gig. In one day of testing the smoothing went from three samples to five, the lock window from ±3 to ±5 cents, the hold time from 500 to 380 ms and the meter range from ±25 to ±50 cents.

It detects which string you're playing, locks when it's steady, gives a haptic tap and celebrates when all six are in tune.