> ## 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. # HappyHorse 1.0 Image-to-Video > - HappyHorse 1.0 image-to-video, generates video from a single first-frame image - `prompt` is optional (when omitted, the first frame drives free interpretation) - Output aspect ratio is auto-determined by the first frame; **does not support** `aspect_ratio` - Asynchronous processing mode, use the returned task ID to [query status](/en/api-manual/task-management/get-task-detail) - Generated video links are valid for 24 hours, please save them promptly ## OpenAPI ````yaml /en/api-manual/video-series/happyhorse1.0/happyhorse-1.0-image-to-video.json POST /v1/videos/generations openapi: 3.1.0 info: title: HappyHorse 1.0 Image-to-Video API description: >- HappyHorse 1.0 image-to-video API, generates video from a single first-frame image 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 endpoints paths: /v1/videos/generations: post: tags: - Video Generation summary: HappyHorse 1.0 Image-to-Video description: >- - HappyHorse 1.0 image-to-video, generates video from a single first-frame image - `prompt` is optional (when omitted, the first frame drives free interpretation) - Output aspect ratio is auto-determined by the first frame; **does not support** `aspect_ratio` - Asynchronous processing mode, use the returned task ID to [query status](/en/api-manual/task-management/get-task-detail) - Generated video links are valid for 24 hours, please save them promptly operationId: createHappyHorse10ImageToVideo requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/VideoGenerationRequest' examples: basic: summary: Basic image-to-video value: model: happyhorse-1.0-image-to-video prompt: Make the cat in the picture run on the grass image_urls: - https://cdn.example.com/cat.png quality: 720p duration: 5 no_prompt: summary: Free interpretation from first frame (no prompt) value: model: happyhorse-1.0-image-to-video image_urls: - https://cdn.example.com/landscape.jpg quality: 1080p duration: 5 seed: 12345 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, token invalid or expired content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: unauthorized message: Invalid or expired token type: authentication_error '402': description: Insufficient quota, top-up 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: happyhorse-1.0-image-to-video 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 - image_urls properties: model: type: string description: Video generation model name enum: - happyhorse-1.0-image-to-video default: happyhorse-1.0-image-to-video example: happyhorse-1.0-image-to-video prompt: type: string description: >- Text prompt, **optional** (when omitted, the first frame drives free interpretation) **Length limits:** - Chinese: up to `2500` characters - Non-Chinese: up to `5000` characters - Excess content is automatically truncated example: Make the cat in the picture run on the grass image_urls: type: array description: >- First-frame image URL, **required** (the first item of the array is taken as the first frame) **Image requirements:** - Supported formats: JPEG, JPG, PNG, WEBP - Resolution: width and height ≥ `300` px - Aspect ratio: `1:2.5` ~ `2.5:1` - File size: ≤ `10MB` - Image URLs must be **publicly accessible (HTTP or HTTPS)**; private OSS, intranet, or authenticated links are not supported items: type: string format: uri minItems: 1 maxItems: 1 example: - https://cdn.example.com/cat.png quality: type: string description: |- Video resolution tier, defaults to `720p` **Options:** - `720p`: Standard clarity, this is the default - `1080p`: HD clarity **Billing note:** Resolution tier directly affects billing enum: - 720p - 1080p default: 720p example: 720p duration: type: integer description: |- Video duration (seconds), defaults to `5` seconds **Range:** - Integer `3` ~ `15` - Duration directly affects billing default: 5 minimum: 3 maximum: 15 example: 5 seed: type: integer description: >- Random seed, default is random **Details:** - Range: `1` ~ `2147483647` - A fixed seed reduces parameter-induced variation when iterating on prompts and improves reproducibility minimum: 1 maximum: 2147483647 example: 42 callback_url: type: string description: >- HTTPS callback URL for task completion **Callback timing:** - Triggered when the task is completed, failed, or cancelled - Sent after billing confirmation is complete **Security restrictions:** - Only HTTPS protocol is supported - Callbacks to private IP addresses are prohibited (127.0.0.1, 10.x.x.x, 172.16-31.x.x, 192.168.x.x, etc.) - URL length must not exceed `2048` characters **Callback mechanism:** - Timeout: `10` seconds - Up to `3` retries after failure (at `1`/`2`/`4` seconds after failure respectively) - Callback response body format is consistent with the task query endpoint response format - A 2xx status code is considered successful; other status codes trigger retries format: uri example: https://your-domain.com/webhooks/video-task-completed VideoGenerationResponse: type: object properties: created: type: integer description: Task creation timestamp example: 1761313744 id: type: string description: Task ID example: task-unified-1761313744-h1i2vcd9 model: type: string description: Actual model name used example: happyhorse-1.0-image-to-video object: type: string enum: - video.generation.task description: Specific type of the task progress: type: integer description: Task progress percentage (0-100) minimum: 0 maximum: 100 example: 0 status: type: string description: Task status enum: - pending - processing - completed - failed - cancelled example: pending task_info: $ref: '#/components/schemas/VideoTaskInfo' description: Video task details type: type: string enum: - text - image - audio - video description: Output type of the task example: video usage: $ref: '#/components/schemas/VideoUsage' description: Usage and billing information ErrorResponse: type: object properties: error: type: object properties: code: type: string description: Error code identifier message: type: string description: Error description message type: type: string description: Error type VideoTaskInfo: type: object properties: can_cancel: type: boolean description: Whether the task can be cancelled example: true estimated_time: type: integer description: Estimated completion time (seconds) minimum: 0 example: 2400 video_duration: type: integer description: Video duration (seconds) example: 5 VideoUsage: type: object description: Usage and billing information properties: billing_rule: type: string description: Billing rule enum: - per_call - per_token - per_second example: per_second credits_reserved: type: number description: Estimated credits consumed minimum: 0 example: 607500 user_group: type: string description: User group category example: default securitySchemes: bearerAuth: type: http scheme: bearer description: >- ##All endpoints require Bearer Token authentication## **Get API Key:** Visit the [API Key Management Page](https://evolink.ai/dashboard/keys) to obtain your API Key **Add to request header:** ``` Authorization: Bearer YOUR_API_KEY ``` ````