Lip sync
Also called lip-sync, lip syncing, AI lip sync
What is lip sync?
Lip sync is the matching of mouth movements to spoken or sung audio so they appear to happen together. It covers performers mouthing to a recording, as in classic TikTok lip-sync videos, the technical alignment of audio and picture in editing, and AI tools that animate a face in a video or photo to match a new voice track.
In editing, bad sync means the sound arrives before or after the mouth moves. Even a small offset is noticeable, so editors line up audio with a clap or waveform. AI lip sync is used for dubbing videos into other languages and for AI avatars that speak a script.
Realistic AI lip sync raises consent questions. Making a real person appear to say something they did not is a form of deepfake, and many platforms require labeling of altered or synthetic media.
Why lip sync matters
Out-of-sync audio makes video feel cheap and distracts from the message. For talking-head content, clean sync is part of basic quality.
AI lip sync can make localized versions of a video for new markets without reshooting. Done openly and with permission, it can cut costs; done without disclosure, it can damage trust.
How to fix lip sync in a video
- Find a clear sync point, such as a clap or a hard consonant like "p" or "b".
- Line up the audio waveform peak with the frame where the mouth closes or the hands meet.
- Nudge the audio a frame at a time until the mouth and sound match.
- Check sync at the start, middle and end, since drift can build over long clips.
- Export and check again on the device viewers will use.
Lip sync FAQ
What is AI lip sync?
AI lip sync uses a model to change or generate a person's mouth movements in video so they match a given audio track, often used for dubbing or AI avatars.
Why is my video audio out of sync?
Common causes are variable frame rate recordings (common on phones and screen recorders), mixed frame rates in one edit, or Bluetooth audio delay during playback. Converting to a constant frame rate usually fixes editing drift.
Related terms
A voiceover is narration recorded separately from the picture and laid over a video to explain, tell a story or guide the viewer.
An AI avatar is a computer-generated person or character that can speak a script on video, with lip movements synced to an AI or recorded voice.
A deepfake is AI-generated or AI-altered video, audio or images that realistically show a real person saying or doing something they did not.
A talking head video shows a person speaking directly to the camera, framed from the chest or shoulders up, often with captions and B-roll.
Text to speech (TTS) is technology that turns written text into spoken audio, used for voiceovers, accessibility and voice assistants.