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.
01What does lip sync mean in AI video?+
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