Audio Sync Fix

Most lip-sync problems come from the recording chain, not the file itself. Screen recorders, capture cards and Bluetooth audio each add their own latency: the picture takes one path through the hardware, the sound takes another, and they arrive a few hundred milliseconds apart. Because that delay is the same for the whole recording, one constant offset fixes it completely — shift the audio by minus the delay and every lip matches again. This is the case this tool handles, and it covers the large majority of "my recording is out of sync" complaints.

The harder case is drift: in sync at the start, noticeably off ten minutes later. That happens when the audio and video clocks run at slightly different rates — say the audio was captured at 44.1 kHz but stamped as 48 kHz — so the gap grows linearly with time. No single offset can fix drift; you need to re-time-stretch the audio, which is what desktop tools like UniConverter sell and what VLC deliberately does not do (VLC only shifts playback, never the file). If your video drifts, the honest fix is to note the offset at the start and at the end, compute the rate difference, and re-encode with ffmpeg's atempo filter — a desktop job this browser tool doesn't attempt.

A final note on the export: browsers can only write WebM, so the corrected file is a real-time re-encode — the video plays through once while the shifted audio is captured. That means export takes as long as the clip, and the video track is re-compressed (a generation of quality loss, usually invisible at these bitrates). The audio, though, is captured straight from the shifted playback with no extra processing. Keep the tab focused during export, and for clips over 15 minutes consider splitting first — a crashed tab loses the whole pass.