An analog-style strobe tuner for guitar, in your terminal.
Tune your guitar by eye, the way an analog strobe tuner does. A selected note spins a virtual reference wheel, your guitar drives a virtual lamp, and the interaction between them paints a pattern that:
- holds still when the string is in tune,
- drifts one way when you're sharp, the other when you're flat.
There's no pitch detection in the display — no cents readout, no "in-tune" light, just the drift, exactly like a real disc-and-lamp strobe.
brew install cshamrick/tap/strobetuneOr tap first, then install by name:
brew tap cshamrick/tap
brew install strobetunecargo install --git https://github.com/cshamrick/strobetuneYou'll need an audio input (built-in mic, interface, …) and ideally a truecolor terminal for the smoothest colours. On macOS, the first run asks for microphone permission.
strobetunePick the string you're tuning — or just play, and strobetune detects it — then watch the pattern. Still means in tune; drifting means off. Colour reinforces it: a steady band reads teal and warms toward blue the faster it drifts.
1-6 select string a toggle auto string detect
t/T next / prev tuning [ ] transpose ∓ semitone
0 reset transpose q quit
Auto-detect is on by default — play any string and it's selected for you.
Press 1–6 to take over manually.
| Preset | Strings 1–6 |
|---|---|
| Standard | E2 A2 D3 G3 B3 E4 |
| Drop D | D2 A2 D3 G3 B3 E4 |
| Open G | D2 G2 D3 G3 B3 D4 |
Transpose shifts every string by 2^(semitones / 12), and the displayed name
follows along (e.g. Standard E♭, Open A).
audio in → mono → band-pass @ reference → half-wave rectify → virtual lamp
selected tuning + string + transpose → active reference frequency → wheel phase
fold(lamp, wheel phase) → accumulate with persistence → strobe image → ratatui
The trick: the accumulator is indexed by reference wheel phase, not by time. Each audio sample's lamp brightness lands in the bin for the wheel's current phase. When the played period matches the wheel's, the bright moments always fall in the same bin — a still band. When it's off, that coincidence point precesses at the beat frequency and the band slides. No frequency is ever measured; the drift is emergent.
The one place a real pitch algorithm appears is auto string detection, which uses a YIN (autocorrelation) estimate to pick which string you're playing — robust to the harmonic coincidences that fool simpler approaches. It only selects the string; the display itself never sees a pitch.
Build steps, the module map, tests, and the release process live in CONTRIBUTING.md. Issues and PRs welcome.
MIT — free to use, modify, and distribute without restriction.
strobetune models the general analog strobe-tuner principle. It isn't affiliated with, compatible with, or equivalent to any commercial tuner product, and uses original naming and visual design.