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Choose the delay, preview the new timing, then export.
When sound arrives before the picture — a common result of screen recording, Bluetooth capture and some conversions — the fix is to push the soundtrack later. This tool inserts silence at the head of the audio by an exact number of milliseconds or by a count of source frames, then plays the corrected timing back so you can confirm it before exporting.
Milliseconds are absolute and portable, which makes them right when you are matching a known device latency — Bluetooth headphones and wireless speakers often sit in the 100–200 ms range. Frames are relative to the video, which makes them right when you are working from an editor’s report or matching another clip in a 30 or 60 fps project. At 30 fps one frame is about 33 ms, and at 60 fps about 17 ms, so a “two frames late” note translates cleanly either way.
Audio arriving after the picture is the more forgiving direction — the brain is used to sound taking time to travel — but the tolerance is not large. Beyond roughly 50 ms most viewers start to sense that something is off, even if they cannot name it, and beyond 100 ms it reads plainly as bad sync. Adjust in small steps and re-watch continuous speech rather than a single word, because one word can look right by accident while the sentence around it does not.
When sound arrives before the picture — you hear a word before the mouth moves. Screen recordings and Bluetooth capture cause this frequently.
Start with the device latency if you know it — Bluetooth is often 100–200 ms. Otherwise adjust in 20 ms steps and preview continuous speech until it locks in.
Milliseconds for device latency, frames when matching an editing timeline. One frame is about 33 ms at 30 fps and 17 ms at 60 fps.
The picture keeps its original length. Silence is added at the head of the audio, so the soundtrack ends slightly earlier relative to the last frames.
Use the advance tool, which trims the head of the audio to pull it earlier — the mirror image of this operation.
