Fix Audio & Video Sync
Move a video’s audio earlier or later without changing picture timing. Adjust the offset in milliseconds, preview the alignment, and export an MP4 with the first audio track shifted. Processing stays on your device.Read more ↓Show less ↑
Free to use · No account or login required · No ads
Your media stays private: processed in your browser, never uploaded to our servers.
Frequently asked questions
Should I use a positive or negative audio offset?
Positive values delay audio: use them when sound happens too early. Negative values advance audio: use them when sound happens too late. For example, +250 delays sound by a quarter of a second. Preview a clear clap or spoken consonant, then verify the export.
Does this fix audio that gradually drifts out of sync?
This version applies a constant offset up to five seconds in either direction. It does not time-stretch audio or repair gradual drift. Browser preview uses separate audio/video playback and is approximate; exported offsets are applied during audio processing.
What happens to the beginning and end of the audio?
Delaying adds silence at the beginning. Advancing removes the corresponding audio from the start. The remaining tail is padded or trimmed to the video length. MP4/MOV picture streams are copied when compatible; other inputs are encoded to H.264. Only the first video and audio streams are exported. Choose a file under 300 MB.
