Techniques & Methods
AI Lip Sync in plain English.
Also known as: lip syncing,talking-head sync,audio-driven animation
The one-sentence version
Making a face in a video move its mouth to match a new audio track, used for dubbing, avatars, and translated videos.
AI lip sync alters the mouth and lower face of a person in a video so that it matches a different audio track, whether a translation, a cloned voice, or a completely new script. Earlier tools produced obviously wrong mouths; current models generate the jaw, lips, teeth, and subtle cheek motion frame by frame and blend them into the original footage. It is the technology behind HeyGen's video translation, Synthesia's avatars, Argil's creator clones, and the dubbing features in ElevenLabs and Captions. Combined with voice cloning it makes a speaker appear to say anything fluently in dozens of languages, which is both the commercial promise and the deepfake risk. Reputable tools require consent checks for cloning a real person and add content credentials or watermarks. Quality varies with lighting, head angle, and how much the face moves; static talking-head footage works best. Full-body gesture generation, which several avatar tools now add, is a separate and harder problem.