The first clap is only one observation
An owned video and separately recorded soundtrack can align at the beginning while disagreeing later. Record at least two recognisable events on both timelines. Keep the measured differences and the observation method; a single opening adjustment cannot describe a changing relationship.
Suppose an imagined clap near the start matches, but another near the end is half a second apart. That suggests investigating rates, capture-clock relationships, edits or interruptions. It does not yet establish which recorder was wrong, and it is not evidence that a fixed delay control is broken.
Check whether either asset has been trimmed, sped up, resampled or converted since capture. Preserve the earliest available versions and the processing history. A later export may have introduced the difference even if both originals were suitable.
Choose a correction that matches the evidence
A constant offset correction moves the whole soundtrack equally. A duration or rate correction changes the relationship over time. Several cuts or a recording restart can require local editing instead of either global choice. Plot a few events before selecting a transformation.
Use a short candidate with a clear explanation of what remains fixed and what changes. Review voice pitch and programme duration if the audio timing is adjusted. A visually aligned endpoint is not enough if the correction makes the performance sound wrong.
Digital audio concepts by Mozilla Contributors is available under CC-BY-SA 2.5 or later. The two-event method here is original production reasoning. Accept the final picture-and-sound package at several points, and retain the correction note rather than describing an unmeasured cause as proven clock drift.
Questions answered
Will one delay value fix a steadily growing mismatch?
A fixed delay changes offset, not the changing rate relationship.
Do two mismatched events prove which recorder caused it?
No. They bound the symptom; provenance and processing history are still needed.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.