> ## Documentation Index > Fetch the complete documentation index at: https://docs.modellix.ai/llms.txt > Use this file to discover all available pages before exploring further. # Vidu Lip Sync > [Core Function] Vidu Lip Sync is a video-to-video audio synchronization model. [Strengths] It excels at reanimating lip movements in an existing video to precisely match a new replacement audio track, while preserving the original face identity. [Best For] Highly recommended for: dubbing videos into different languages, correcting spoken dialogue post-production, and creating realistic digital avatars. [Limitations] Do NOT use this model if you need to change body movements or generate a new video from scratch. It requires a pre-existing video and a clear audio track. [Routing] Use this model specifically when the user wants to change what a person in a video is saying. If the user wants to transfer body movements, use Vidu Motion Sync instead. ## OpenAPI ````yaml /model-api/vidu/vidu-v2v.json post /vidu/lip-sync openapi: 3.1.0 info: description: >- The video-to-video models API from Vidu. Includes motion sync, lip sync, and one-click trending replicate. version: 1.0.0 contact: name: Modellix Support email: support@modellix.ai title: Vidu Video-to-Video Models API servers: - url: https://api.modellix.ai/api/v1 description: The video-to-video models API from Vidu. security: - bearerAuth: [] paths: /vidu/lip-sync: post: summary: Vidu Lip Sync description: >- [Core Function] Vidu Lip Sync is a video-to-video audio synchronization model. [Strengths] It excels at reanimating lip movements in an existing video to precisely match a new replacement audio track, while preserving the original face identity. [Best For] Highly recommended for: dubbing videos into different languages, correcting spoken dialogue post-production, and creating realistic digital avatars. [Limitations] Do NOT use this model if you need to change body movements or generate a new video from scratch. It requires a pre-existing video and a clear audio track. [Routing] Use this model specifically when the user wants to change what a person in a video is saying. If the user wants to transfer body movements, use Vidu Motion Sync instead. operationId: viduLipSyncAsync requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ViduLipSyncRequest' examples: with_audio: summary: Replace audio track value: video_url: https://example.com/presenter-video.mp4 audio_url: https://example.com/new-voiceover.mp3 with_reference_face: summary: With reference face for identity value: video_url: https://example.com/video.mp4 audio_url: https://example.com/audio.mp3 reference_face_image_url: https://example.com/face-reference.jpg responses: '200': description: Task submitted successfully content: application/json: schema: $ref: '#/components/schemas/AsyncTaskResponse' example: code: 0 message: success data: status: pending task_id: task-vidu-lsync-001 model_id: vidu/lip-sync get_result: method: GET url: https://api.modellix.ai/api/v1/tasks/task-vidu-lsync-001 '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalServerError' components: schemas: ViduLipSyncRequest: type: object required: - video_url description: >- Vidu lip sync request. Synchronizes lip movements in the source video to match the provided audio track. properties: video_url: type: string minLength: 1 description: Source video URL containing the face to reanimate. example: https://example.com/talking-head.mp4 audio_url: type: string minLength: 1 description: >- Replacement audio track URL. The model will reanimate the speaker's lips to match this audio. example: https://example.com/new-voiceover.mp3 reference_face_image_url: type: string minLength: 1 description: >- Reference face image URL. When provided, the model uses this face to preserve identity consistency throughout the video. example: https://example.com/face-reference.jpg AsyncTaskResponse: type: object required: - code - message - data properties: code: type: integer description: Response code, 0 indicates success example: 0 message: type: string description: Response message example: success data: type: object required: - status - task_id - model_id properties: status: type: string enum: - pending - processing description: Task status example: pending task_id: type: string description: Unique task identifier for polling example: task-abc123 model_id: type: string description: Model ID in `provider/model` format example: vidu/viduq3-mix-r2v get_result: type: object description: API information to query the task result properties: method: type: string example: GET url: type: string example: https://api.modellix.ai/api/v1/tasks/task-abc123 description: Detailed data about the submitted asynchronous task. ErrorResponse: type: object required: - code - message properties: code: type: integer example: 400 message: type: string example: 'Invalid parameters: parameter ''reference_images'' is required' responses: BadRequest: description: Invalid request parameters content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 400 message: 'Invalid parameters: parameter ''reference_images'' is required' Unauthorized: description: Unauthorized - Invalid or missing API Key content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 401 message: 'Authentication failed: invalid API key' TooManyRequests: description: Too many requests - Rate limit exceeded headers: X-RateLimit-Limit: description: Maximum requests per minute schema: type: integer example: 100 X-RateLimit-Remaining: description: Remaining quota in current window schema: type: integer example: 0 X-RateLimit-Reset: description: Rate limit window reset time (Unix timestamp) schema: type: integer example: 1704067260 content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 429 message: >- Rate limit exceeded: 100 requests per minute, retry after 60 seconds InternalServerError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 500 message: Internal server error securitySchemes: bearerAuth: type: http scheme: bearer description: 'API Key authentication. Format: `Bearer YOUR_API_KEY`.' ````