AI video interaction glossary
Lip sync means matching visible mouth movement to speech. In an AI avatar call, it helps the face appear to say the voice you hear. It is a visual timing capability: it does not establish how intelligently the character responds, whether you can interrupt it or whether it sees you.
Definition
Lip sync, short for lip synchronization, aligns the visible movement of a mouth with spoken audio. An avatar system may map sounds to mouth shapes or generate facial animation from the audio signal. Lip sync can be used in a prerecorded clip as well as a live conversation, so synchronized lips alone are not evidence of a two-way video call.
By the Prelulu editorial team · Updated
A documented example of converting audio into facial animation; it does not establish another app’s architecture or performance.
Watch a character say a short sentence with clear changes in sound, then listen and look together. Notice whether the mouth keeps moving after the audio ends or visibly lags behind it. This checks synchronization; it is not a test of the character’s memory or reasoning.
A mouth shape associated with a speech sound is often called a viseme. Expressions such as a smile or raised eyebrow may be controlled separately. A face can have good lip sync while using a limited set of gestures or emotional expressions.
An app offering lip sync might provide video messages, generated clips or an interactive call. To tell them apart, check whether you can speak during the experience and receive a new response to what you just said.
FAQ
No. Audio-driven mouth animation can be implemented with different visual representations. The result on screen does not by itself tell you whether the system used a 3D model, an image or generated video.
No. Lip sync aligns mouth movement with audio. Full duplex describes simultaneous audio in both directions. A prerecorded video can have excellent lip sync and no interaction at all.
Audio playback, animation generation and video delivery have to stay aligned. A timing mismatch anywhere in that chain can make the face lag. The precise cause depends on the implementation and connection.
Choose a character for conversation, roleplay or a live call. Check the current plans and available credits before calling.
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