> ## 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. # Lip Sync > [Core Function] PixVerse Lip Sync drives a talking video so the subject's lips match given audio or text-to-speech. [Strengths] Accurate lip synchronization for talking-head videos; supports either an existing audio track or TTS from a chosen speaker voice. [Best For] Dubbing, virtual presenters, character dialogue, localizing spoken video. [Limitations] Do NOT use this to generate new motion or change content; it only re-times the subject's lips on an existing video. It requires an input video, and you must provide EITHER audio_url OR (speaker_id + tts_content), not both. [Routing] Use when the user has a video and wants the speaker's lips to match speech. Use audio_url for an existing voice track; use speaker_id (a named voice code) + tts_content (max 140 chars) to synthesize speech from text. ## OpenAPI ````yaml /model-api/pixverse/pixverse-v2v.json post /pixverse/lipsync openapi: 3.1.0 info: description: >- The video-to-video models API from PixVerse. Includes lip sync, restyle, extend, motion control (mimic), and upscale. Tasks are asynchronous: submit, then poll the task endpoint for the result. version: 1.0.0 contact: name: Modellix Support email: support@modellix.ai title: PixVerse Video-to-Video Models API servers: - url: https://api.modellix.ai/api/v1 description: The video-to-video models API from PixVerse. security: - bearerAuth: [] paths: /pixverse/lipsync: post: summary: Lip Sync description: >- [Core Function] PixVerse Lip Sync drives a talking video so the subject's lips match given audio or text-to-speech. [Strengths] Accurate lip synchronization for talking-head videos; supports either an existing audio track or TTS from a chosen speaker voice. [Best For] Dubbing, virtual presenters, character dialogue, localizing spoken video. [Limitations] Do NOT use this to generate new motion or change content; it only re-times the subject's lips on an existing video. It requires an input video, and you must provide EITHER audio_url OR (speaker_id + tts_content), not both. [Routing] Use when the user has a video and wants the speaker's lips to match speech. Use audio_url for an existing voice track; use speaker_id (a named voice code) + tts_content (max 140 chars) to synthesize speech from text. operationId: pixverseLipSyncAsync requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/PixverseLipSyncRequest' examples: audio: summary: Audio-driven value: video: https://example.com/talk.mp4 audio_url: https://example.com/voice.mp3 tts: summary: TTS-driven value: video: https://example.com/talk.mp4 speaker_id: emily tts_content: Hello, welcome to our product demo. 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-pixverse-lipsync-001 model_id: pixverse/lipsync get_result: method: GET url: >- https://api.modellix.ai/api/v1/tasks/task-pixverse-lipsync-001 '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalServerError' components: schemas: PixverseLipSyncRequest: type: object required: - video description: >- PixVerse lip sync request. Requires an input video plus a speech source: provide EITHER audio_url, OR speaker_id together with tts_content. audio_url and speaker_id are mutually exclusive; tts_content requires speaker_id. properties: video: type: string minLength: 1 description: Input talking video URL (publicly accessible). example: https://example.com/talk.mp4 audio_url: type: string description: >- Audio track URL to lipsync against. Mutually exclusive with speaker_id/tts_content. example: https://example.com/voice.mp3 speaker_id: type: string enum: - emily - james - isabella - liam - chloe - adrian - harper - ava - sophia - julia - mason - jack - oliver - ethan - auto description: >- TTS speaker voice (semantic code; as of 2026-06-26): emily, james, isabella, liam, chloe, adrian, harper, ava, sophia, julia, mason, jack, oliver, ethan, or auto (auto-select). Use together with tts_content. Mutually exclusive with audio_url. example: emily tts_content: type: string maxLength: 140 description: >- Text (<=140 chars) to synthesize into speech with speaker_id. Requires speaker_id. example: Hello, welcome to our product demo. 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: pixverse/lipsync 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 ''video'' is required' responses: BadRequest: description: Invalid request parameters content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 400 message: 'Invalid parameters: parameter ''video'' 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`.' ````