Source video and target audio
- Input requires one video URL and one audio URL.
- Video files can be MP4, QuickTime or Matroska-style containers up to 500MB.
- Audio files can be MP3, WAV, AAC, MP4 or OGG style formats up to 10MB.
UlazAI - AI Image & Video Tools
Video-to-video voice sync
AI video lip sync generator
Turn an existing talking clip into a synced version with a new voice, translation, narration or vocal track. This route does not create a new face or scene; it uses your source video and drives the visible mouth movement from the target audio.
8 credits/s. Final output length follows the target audio.
Localizing creator videos, lessons and product explainers without regenerating the whole scene.
Replacing a rough voice take with a clean final recording.
Matching a presenter clip to a translated script or a new narration pass.
Repurposing existing talking-head footage into new campaign variants.
Model video
Input, sample and route in one launch clip
Use this as the quick model check before generating: accepted input, generated output and the clearest route in Video Studio.
Input Pick the route from the asset you already have.
Sample Watch generated clips before you spend credits.
Route Clear prompt, clear pricing, clear next step.
Generated sample
Presenter clip with replaced voice
Input: one public presenter video URL plus one public voiceover MP3.
Prompt
Source presenter video keeps its framing while the spoken line is replaced by the UlazAI launch voiceover.
What the lip sync route controls
This is a video-to-video workflow. The better the source face visibility and target vocal track, the stronger the sync.
Mode choices that matter
- Lite mode is the fastest option for direct replacement and alignment workflows.
- Basic mode is better when scene segmentation or speaker handling is needed.
- Vocal separation can suppress background noise when the audio track is not perfectly clean.
Audio alignment
- If the audio is shorter, the visual source can be trimmed to the audio length.
- If the audio is longer, lite mode can loop the video forward or backward to fill the track.
- Use a clean vocal file when mouth shape precision matters.
Where it fits
| Duration | 720p / base | 1080p |
|---|---|---|
| 5s | 40 credits | - |
| 10s | 80 credits | - |
| 30s | 240 credits | - |
| 60s | 480 credits | - |
Production uses
Use lip sync when the original performer, face, framing or product demo already works and only the spoken track needs to change.
Course and training localization
Keep the same lesson video and align the presenter to a translated voice track.
Product demo revisions
Replace outdated narration in a demo video while keeping the screen recording or presenter framing intact.
Creator reposts
Turn one talking-head clip into multiple language or script variants without rebuilding the scene.
Campaign voice swaps
Test new spoken hooks, offers or localized lines against the same visual performance.
Studio routes
Video to Video Lip Sync
video_lip_sync
Estimated from selected length; output follows audio duration
Requires one source video URL and one target audio URL.
Open routeHow it differs from text-to-video
Lip sync does not invent a new scene from a prompt. It uses your existing video as the visual source and uses the audio URL to drive the mouth timing.
Production workflow
- Prepare a source video where the mouth is visible and not blocked by fast cuts.
- Export the target audio as clean vocal speech with the final script and no long silence.
- Paste both public URLs in Video Studio and choose the mode that matches the footage.
- Use alignment settings when the audio is longer or shorter than the source video.
- Review mouth timing before cutting the result into an ad, lesson or social edit.
FAQ
What input does AI Video Lip Sync need?
One public source video URL and one public target audio URL.
How is the final duration decided?
The final output follows the audio duration. A longer source can be trimmed; a shorter source can be looped when alignment is enabled.
Which video formats are accepted?
Use MP4, QuickTime or Matroska-style video files up to 500MB.
Which audio formats are accepted?
Use MP3, WAV, AAC, MP4 or OGG style audio files up to 10MB. A clean vocal track usually gives the best result.
What is the difference between lite and basic mode?
Lite is the faster alignment route. Basic is better when scene segmentation or speaker handling is needed.
What does it cost?
The route costs 8 credits per output second.
When should I not use lip sync?
Do not use it when you need a new person, a new scene or a fully generated video from a prompt. Use a text-to-video or image-to-video model instead.