Does holding a fitted clock slope between audio re-syncs let free-running cameras go longer without a refresh?
research/capture-syncslope
Does holding a fitted clock slope between audio re-syncs help? At 40 ppm it cuts out-of-tolerance time from 44% to 3.7% at 1800 s intervals, but an assumed rate wobble makes a strict line gate lock out. Synthetic audio; also corrects capture-syncbudget.
What it found
Follow-up to capture-syncbudget on synthetic speech-like audio (capture-audiosync's GCC-PHAT, window cut with the current correction so only the residual is searched). With a steady 40 ppm clock error, holding a fitted line instead of the last offset cuts the share of a 6 h shoot beyond 40 ms (EBU R37 lead limit, a stand-in for a cut threshold) from 44% to 3.7% at one re-sync per 1800 s and from 72% to 12% at 3600 s; the remainder is the first interval. With an assumed 10 to 30 ppm rate wobble a strict line gate locks out true estimates (69–88% bad at 300 and 900 s); resetting after two rejections fixes 300 s but at 900 s and 30 ppm the plain offset hold wins (13% vs 27%). Also corrects capture-syncbudget, whose raw-window correlation let the delay outgrow the 2 s window. Wobble amplitudes are swept, not measured; no real recording.
Paper, code and results
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.