Metronome
A click you can
actually trust.
Not a timer callback. The Strofa metronome is built on AVAudioEngine — sample-accurate click sounds scheduled against the audio hardware clock. No drift, no compensation hacks.
Sample-accurate timing
The same timing you'd get from a hardware drum machine.
Most phone metronomes schedule their clicks using JavaScript timers or iOS display refresh callbacks. Both drift by 5–15 milliseconds over time. On a 160 BPM song that drift is audible within two bars, and compounds across a whole set.
The Strofa metronome is a native Swift module (strofa-metronome) built on AVAudioEngine + AVAudioPlayerNode.scheduleBuffer. Click sounds are synthesized in Swift and scheduled as sample-offset events against the audio hardware clock — the same approach used by Logic Pro and professional hardware metronomes. There is no drift.
The click itself is a short sine burst: 2 000 Hz accent on beat one, 1 500 Hz downbeat on beats two, three and four. Designed to cut through stage monitoring without harshness. Volume is adjustable independently of system volume.
- AVAudioEngine + scheduleBuffer — sample-level timing
- No drift over any duration
- Click volume independent of system volume
- Accent beat 1 · downbeats 2–4 at different pitch
- Runs concurrently with backing track playback
Long-press the ♩ icon to enter tap mode. Tap 4+ times to set tempo — Strofa averages the interval and updates the BPM immediately.
{tempo: 120 4/4}
Add this to any song and the metronome starts at 120 BPM in 4/4 the moment you open the song. No tapping needed.
In practice
Tap, flash, auto-start.
Tap the ♩ icon in the song header to start. Tap again to stop. The tempo comes from the song's stored BPM — or from the last tap tempo you set if no tempo is stored.
Tap tempo: long-press the ♩ icon to enter tap mode. Tap at least twice to set the tempo; Strofa averages the last four taps for stability. The BPM updates in real time as you tap. The result is stored on the song and used next time.
A red beat flash appears in the song header and in the iOS home indicator bar on every beat. It's visible in your peripheral vision while you read the chart — so you can feel the pulse without looking up.
Auto-start is the most useful live feature: add {tempo: 120 4/4} to a song and the metronome starts automatically at that tempo when you open the song. Five songs in a row, each with its own tempo — the click changes automatically with each switch.
Time signatures supported: 4/4, 3/4, 6/8, 5/4, 7/8. Set in the song editor or via the {time} directive.
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In time. Every time.
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