First determine whether the sound has a fixed offset or progressively drifts. Variable-frame-rate media is one possible contributor, not an explanation for every sync problem. Changing a clip’s interpreted frame rate can change duration and make a timing problem worse.
On this page
Classify the symptom
| Pattern | Useful first investigation |
|---|---|
| Same offset throughout | Start alignment, recording offset or synchronization step |
| Drift grows over time | Duration, timestamp, sample-rate or clock differences |
| Sudden jump at one point | A cut, missing section, edit or localized source problem |
Use visible events with audible counterparts, such as a clap or a hard object contact. Check near the beginning, middle and end. Do not rely on a single waveform peak when room reflections or unrelated sounds can obscure the reference.
Keep source timing separate from playback labels
A video’s displayed frame-rate label can be rounded or averaged. A variable-rate recording can carry frame timestamps that are not uniformly spaced. The application’s handling of those timestamps matters more than simply reading “30 fps” from one property panel.
Try a duration-preserving sample conversion
- Duplicate the source and project before changing anything.
- Record the original duration and examine a short section with a clear sync reference.
- If the editor or vendor documents a timing issue, test a conversion that preserves duration and uses an explicit constant-rate output.
- Keep the originals. Check the converted sample’s picture, audio layout and timing.
- Replace or relink only in the duplicate project and inspect the beginning, middle and end again.
- Process the long recording only after the sample workflow is reliable.
Do not confuse conversion with reinterpretation
A clip containing 2,400 frames lasts 100 seconds at 24 fps. Reinterpreting those same frames at 25 fps produces 96 seconds. A duration-preserving conversion instead needs 2,500 output frames, with a deliberate duplicate/drop/interpolation policy. Try the frame-rate tool for the arithmetic.
If the drift remains
Investigate the audio recording path, clock and sample-rate handling, edits, and whether the problem exists in the source or only after export. Note the exact application version; a beta feature or forum comment is not evidence for the installed release. See bounded troubleshooting.
Sources and scope
The timing figures are arithmetic examples. This guide does not claim that all variable-rate files fail or that a conversion repairs every audio-sync issue. Sources checked October 6, 2026.