> ## Documentation Index > Fetch the complete documentation index at: https://docs.evolink.ai/llms.txt > Use this file to discover all available pages before exploring further. # Veo3.1-Fast Video Generation > - Veo 3.1 Fast Generate Preview supports text-to-video, first-frame image-to-video and more - Async processing, use returned task ID to [query status](/en/api-manual/task-management/get-task-detail) - Generated video links are valid for 24 hours, please save promptly ## OpenAPI ````yaml /en/api-manual/video-series/veo3.1/veo-3.1-fast-generate-preview-generate.json POST /v1/videos/generations openapi: 3.1.0 info: title: Veo-3.1-Fast-Generate-Preview API description: >- Create video generation tasks using AI models, supporting text-to-video, image-to-video and more license: name: MIT version: 1.0.0 servers: - url: https://api.evolink.ai description: Production security: - bearerAuth: [] tags: - name: Video Generation description: AI video generation APIs paths: /v1/videos/generations: post: tags: - Video Generation summary: Veo-3.1-Fast-Generate-Preview API description: >- - Veo 3.1 Fast Generate Preview supports text-to-video, first-frame image-to-video and more - Async processing, use returned task ID to [query status](/en/api-manual/task-management/get-task-detail) - Generated video links are valid for 24 hours, please save promptly operationId: createVideoGeneration requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/VideoGenerationRequest' examples: text_to_video: summary: Text-to-Video value: model: veo-3.1-fast-generate-preview prompt: A cat playing piano responses: '200': description: Video generation task created successfully content: application/json: schema: $ref: '#/components/schemas/VideoGenerationResponse' '400': description: Invalid request parameters content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: invalid_request message: Invalid request parameters type: invalid_request_error '401': description: Unauthenticated, invalid or expired token content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: unauthorized message: Invalid or expired token type: authentication_error '402': description: Insufficient quota, recharge required content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: insufficient_quota message: Insufficient quota. Please top up your account. type: insufficient_quota '403': description: Access denied content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: model_access_denied message: >- Token does not have access to model: veo-3.1-fast-generate-preview type: invalid_request_error '429': description: Rate limit exceeded content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: rate_limit_exceeded message: Too many requests, please try again later type: rate_limit_error '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: internal_error message: Internal server error type: api_error components: schemas: VideoGenerationRequest: type: object required: - model - prompt properties: model: type: string default: veo-3.1-fast-generate-preview example: veo-3.1-fast-generate-preview prompt: type: string description: Prompt describing the video, max 2000 tokens example: A cat playing piano maxLength: 2000 image_urls: type: array description: >- Reference image URLs, max 3 images (FIRST&LAST mode supports 1-2, REFERENCE mode supports up to 3), max 10MB each items: type: string format: uri maxItems: 3 generation_type: type: string description: >- Generation mode: - `TEXT`: Text-to-video - `FIRST&LAST`: First-last frame, 1-2 images - `REFERENCE`: Reference image, max 3 images, duration fixed at 8s, aspect ratio fixed at 16:9, except `generate_audio`, other advanced params not supported enum: - TEXT - FIRST&LAST - REFERENCE aspect_ratio: type: string description: >- Video aspect ratio. When set to `auto`: image-to-video will automatically select based on the input image ratio, text-to-video will automatically select based on the prompt content enum: - auto - '16:9' - '9:16' generate_audio: type: boolean description: Generate audio (extra cost), default `true` duration: type: integer description: Duration (seconds), default `4` enum: - 4 - 6 - 8 'n': type: integer description: Number of videos, default `1` minimum: 1 maximum: 4 quality: type: string description: Resolution, default `720p` enum: - 720p - 1080p - 4k seed: type: integer minimum: 1 maximum: 4294967295 negative_prompt: type: string person_generation: type: string description: Person generation control, default `allow_adult` enum: - allow_adult - dont_allow resize_mode: type: string description: Resize mode (I2V only), default `pad` enum: - pad - crop callback_url: type: string format: uri VideoGenerationResponse: type: object properties: created: type: integer example: 1757169743 id: type: string example: task-unified-1757169743-7cvnl5zw model: type: string example: veo-3.1-fast-generate-preview status: type: string enum: - pending - processing - completed - failed ErrorResponse: type: object properties: error: type: object properties: code: type: string description: Error code identifier message: type: string description: Error description type: type: string description: Error type securitySchemes: bearerAuth: type: http scheme: bearer description: >- ##All APIs require Bearer Token authentication## **Get API Key:** Visit [API Key Management Page](https://evolink.ai/dashboard/keys) to get your API Key **Add to request header:** ``` Authorization: Bearer YOUR_API_KEY ``` ````