Does a longer window, a lower gamma or a delay prior fix the period aliasing and early-start failures of GCC audio sync on real clips?

What it found

Follow-up to capture-residgate section D. On ten real LibreOffice gallery clips (0 dB white noise, 0.8 s offset, 432 windows per clip and cell), the share of delay estimates over 2 ms off on the four failing clips falls from 97% at a 1 s window to 38% at 2 s and 16% at 3 s (gamma 0.25), because two cameras with a 0.8 s offset share only W−0.8 s of audio. Gamma moves 2 s results between 38% and 76% (PHAT worst). A tone clip (space2) is not helped by more audio (52–70% aliased at 2 and 3 s); only a delay prior tighter than its 12 ms period works (oracle ±10 ms: 0% wrong; ±50 ms: 65% still aliased). The early-start failures of untie and soft (59–77% wrong when the window starts in the clip's first half second, 0% later) are partly a short shared segment; the shared audio is only 2–5 dB quieter in wrong windows, so loudness is a weak explanation. Limits: ten clips, white noise at one SNR, 3 s windows barely vary their start (one draw of content per clip), the prior is an oracle ceiling.

Paper, code and results

• README and method
• Experiments and results
• Code
• Tests

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Other research topics

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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.