What is Lip Sync?
AI capability that synchronizes character lip movements with audio dialogue. Essential for talking-head videos and any content featuring speech.
How it works
Lip sync technology matches character mouth movements to audio input. In AI video, this means generating or modifying video so that a character appears to naturally speak given dialogue. There are two approaches: generation-time lip sync, where the AI creates lip-synced video from scratch (as in Veo 3.1 and HeyGen), and post-generation lip sync, where existing video is modified to match new audio. Generation-time lip sync produces more natural results but requires tools that support it natively. Post-generation lip sync is more flexible but can produce uncanny artifacts. For professional talking-head content, HeyGen and Synthesia are purpose-built solutions, while Veo 3.1 offers lip sync as part of its generative video output.
Tools that use lip sync
Related terms
Frequently asked questions
What does lip sync mean in AI video?▾
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