> ## Documentation Index
> Fetch the complete documentation index at: https://api-docs.voicecheap.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# How lip sync works

> Understand what VoiceCheap changes in the frame, how audio drives mouth movement, and where lip sync fits into the dubbing workflow.

# How lip sync works

Lip sync takes a source video and a new audio track, then updates the speaker’s mouth movements so they better match the translated speech.

## What changes and what stays the same

VoiceCheap focuses on the speaking face region. In practice:

* the mouth and lower-face motion are updated
* the target audio drives the new mouth movement
* the rest of the frame stays as intact as possible

## The high-level pipeline

<Steps>
  <Step title="Detect the face">
    VoiceCheap identifies the speaking face and tracks the relevant facial landmarks around the mouth and lower face.
  </Step>

  <Step title="Analyze the translated audio">
    The system listens to the target audio and computes the mouth shapes needed to match the speech.
  </Step>

  <Step title="Generate new lip movement">
    The speaking region is regenerated frame by frame to match the translated audio more closely.
  </Step>

  <Step title="Blend the result back into the video">
    The generated mouth region is composited back into the original frame so the result stays visually coherent.
  </Step>
</Steps>

## Where lip sync fits in the workflow

Lip sync is not the first quality step. The usual order is:

1. get the transcript right
2. choose the voice strategy
3. make sure the dubbed audio sounds natural
4. add lip sync if the project benefits from it

If the translated voice or timing still sounds wrong, fix that first. Lip sync works best when the audio is already in good shape.

## Limitations to expect

* strong profile views are harder than front-facing shots
* heavy obstructions around the mouth reduce quality
* shaky footage reduces face-tracking reliability
* noisy or overlapping audio can reduce the naturalness of the final result

## Related pages

* [Lip sync overview](/docs/lip-sync/overview)
* [Best practices](/docs/lip-sync/best-practices)