Video editing · browser-local beat-to-frame planning · 2026 · Solo — product framing, test-first timing logic, interaction design, accessibility, responsive verification, production deployment
Tempo Register
A frame-accurate marker bench that keeps unavoidable beat rounding from accumulating down a video timeline.
The problem
Video editors cutting picture to music can calculate a beat interval in seconds, but a video edit must ultimately place every cut on an integer frame. When a pulse spans a fractional number of frames, repeatedly using one rounded interval creates cumulative drift; meanwhile, a raw list of timestamps hides which individual markers land early or late. Tempo Register keeps that narrow translation inspectable: set BPM, project frame rate, subdivision, marker count, and starting frame; generate each marker from its absolute ideal phase; inspect ideal pulse and snapped frame on one lattice; then copy the exact frame sequence with signed error. It provides nearest-frame planning guidance rather than audio analysis or an interchange file. Variable-frame-rate media, drop-frame timecode labels, playback latency, musical onset detection, and editorial judgment remain outside its boundary. Values stay in ephemeral browser state; there is no media upload, account, persistence, paid API, tracking SDK, outbound email, advertising, payment, or destructive operation. Production deployment dpl_8ikWfKwgB4zuJ8yntLDHZLeEUkZ7 reached READY before independent Foundry artifact, HTTPS marker, and six-step behavior checks passed at the stable alias.
Architecture
Key decisions
Round absolute phase, not the previous gap
Every marker starts from its ideal musical position before snapping to the nearest frame. The resulting short and long gaps distribute rounding instead of letting one rounded interval accumulate error.
Make phase disagreement the operating surface
The lattice is not decorative waveform art. Each red pulse and cyan frame target derives from the same tested marker, while selection connects that offset to frame, milliseconds, gap, and ledger row.
Keep the timing claim narrow
Tempo Register performs deterministic arithmetic only. It does not listen to audio, detect transients, label drop-frame timecode, inspect source frame cadence, or decide where an edit should cut.
Use a technical cutting bench without cloning a brand
Bone control stock, near-black inspection space, vermilion pulse marks, cyan frame targets, acid cadence type, Archivo Narrow, and IBM Plex Mono create a direct clock-to-lattice-to-ledger composition without gradients, blur, feature tiles, icon toppers, or decorative metrics.
Let the real browser harden the handoff
The first Golden Path exposed that a present-but-denied Clipboard API skipped the fallback. A failing browser check preceded the narrow permission fallback fix, after which local and production six-step paths passed.