Cadentia

Cadentia splits any song into four stems (vocals, bass, drums and the rest) inside the iPhone itself, with nothing uploaded to a server. Remove the vocals and sing over it as karaoke, isolate the bass to learn it by ear, or practise over what is left. Free, no account, no ads. In the same app: tuner, metronome, drums, piano, tablature and a multitrack recorder, all working with the phone in airplane mode.

STEM SEPARATION ON THE DEVICE
Pick a song from your library and Cadentia splits it into four tracks with a Core ML model that runs on your iPhone. Mute the vocals and you have a backing track; mute the rest and you have just the bass or just the drums. The karaoke apps that do this send the song to the cloud and charge a subscription. Here nothing leaves the device, and it costs nothing.

A TUNER THAT DOESN'T WOBBLE
Pitch detection through the YIN algorithm, accurate to about one cent. The ring runs red, amber, green; the note sits in the middle and the deviation in cents just above it. Reference pitch goes from 415 to 466 Hz, for orchestra players and period instruments. There is also Analyse tuning: play for up to a minute and see how much of it you spent in tune.

A METRONOME THAT DOESN'T DRIFT
The click is scheduled on the audio clock, not the screen clock, so it still lands where it should after ten minutes. Time signatures from 2/4 to 7/8, subdivisions, polyrhythm, tap tempo, a microphone BPM detector and a practice timer. It plays through the silent switch, which is half the reason to build a metronome natively.

REAL DRUMS AND A REAL PIANO
The pads and the keys don't fire samples: the sound is synthesised as you play, with Bessel-mode membranes on the drums and true inharmonicity on the piano. In practice: how hard you hit changes the timbre, not just the volume. Sixteen-step sequencer, 25 ready grooves, a vertical multitouch keyboard, 77 chords and 144 scales.

TABLATURE WITH A BAND BEHIND IT
Open and edit multitrack tablature with bass, drums and 48 backing tracks. It is the same .rostab file you write in RoqueOS in the browser: back and forth, nothing to convert.

MULTITRACK RECORDER
Play over what you already recorded, with Apple's echo cancellation and noise reduction. The timeline actually edits: trim, split, fade, pan, undo. Export the mix as M4A when you're done.

YOUR LIBRARY, IF YOU WANT IT
If you use RoqueOS, you can pair Cadentia with your account using a short code and play the music already there. It is the only part of the app that uses the internet, and it is optional: without pairing, everything else works the same.

No ads, no charge, no in-app purchases. In 10 languages.