visual-cadence

Static-gap measurement. Runs in the finishing phase right AFTER qc-clip passes, on the final clip. It is the union-of-all-visual-changes counterpart to the per-skill cut planners — jump-cut, zoom-punch, and b-roll each place cuts blind to one another, so only a post-render measure tells you what a viewer actually sees. It is the keystone signal for the "12 seconds without a pattern interrupt" retention leak diagnosed on the channel.

visual-cadence.sh <clip.mp4> [out.json=<clip>.cadence.json] [max_gap=5.0]

• How. ffmpeg ... -vf select='gt(scene,VCAD_SCENE)',showinfo flags frames whose scene-change score exceeds the threshold; the script parses their pts_time, treats [0, ...cuts..., dur] as boundaries, and reports the largest gap. Hard cuts (b-roll) and strong reframes (jump-cut) register; gradual zoom-punch pulses intentionally do not count as a "change."
• Output. {pass, duration, threshold, scene, n_changes, max_gap, gap_window:[a,b], changes:[...]}.
• Diagnostic only. Always exits 0 (usage/missing-input aside); it writes the verdict and logs a WARN when max_gap > MAX_STATIC_GAP, but never blocks the save. The real fix lives upstream in jump-cut coverage; this surfaces regressions.
• Idempotent via .vcadmeta. VISUAL_CADENCE=0 disables.

Knobs: VISUAL_CADENCE (0 disables), MAX_STATIC_GAP (default 5.0s), VCAD_SCENE (scene-detect threshold, default 0.3).