RastAnother Song Transformer

Chord detection, beat tracking, source separation, and real-time pitch & speed — analyze any recording and practice along with it.

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Chord detection

CREMA neural network identifies chords frame-by-frame. Edit them by hand with a hover-through chord picker, ripple editing, undo/redo.

Modal scale detection

Eleven modes including non-Western flavours like Hidjaz, Nikriz, Sabah, and Niavent — disambiguated from chord context plus weighted chroma matching, where Western tools just round to major or minor.

Beat tracking

beat_this DBN finds beats and downbeats. A built-in metronome clicks through the bar grid for practice.

Source separation

Pull vocals out of the mix with Spleeter or Demucs. Mix stems independently while you practice along.

Real-time pitch & speed

Transpose ±12 semitones or slow down to 50% with no pitch artifacts, via SoundTouch in a WebAudio worklet.

Local-first

Tauri desktop app. Audio, models, and analysis all live on your machine. No telemetry, no cloud round-trips.

Support development ☕

Rast is free — no ads, no telemetry, no cloud, no subscription. Built by one person in their spare time. If it replaced a paid tool or saved you a practice session, a small tip keeps development going.

Buy me a coffee ☕