# Happy Horse 1.1 - Core.Today AI API

> Alibaba's Happy Horse 1.1 generates videos from text, animates a single image, or builds a video from multiple reference images. Supports 720p and 1080p, 3-15 second durations, and five aspect ratios.

- **Provider**: Alibaba
- **Model ID**: alibaba/happyhorse-1.1
- **Category**: Video Generation
- **Credits**: 2090 per 5s 1080p video — billed per second (720p 326/s, 1080p 419/s)
- **Speed**: Medium
- **Quality**: High

## Features
- Three modes in one model: text-to-video, image-to-video, reference-to-video
- Reference-to-video with up to 9 images — keeps subjects and scenes consistent
- 720p and 1080p output at 3-15 second durations
- Five aspect ratios: 16:9, 9:16, 1:1, 4:3, 3:4
- Seed support for reproducible generation

## Use Cases
- Animating a still image as the opening frame of a video
- Character-consistent scenes built from multiple reference images
- Short-form vertical (9:16) content for social media
- Product showcase videos combining reference shots
- Cinematic text-to-video clips up to 15 seconds

## API Endpoint

Base URL: https://api.core.today/v1
Create Prediction: POST /predictions
Get Status: GET /predictions/{job_id}

## Authentication
Header: X-API-Key: YOUR_API_KEY

## Input Parameters

### Optional
- **prompt**: string - Text prompt (up to 2,500 chars). Optional with a single image; required for text-to-video and reference-to-video. Refer to reference images as [Image 1], [Image 2], etc.
- **images**: array (default: []) - No images for text-to-video, one image to animate it (image-to-video), or up to 9 for reference-to-video. jpg/png/bmp/webp, ≤10MB each, each side ≥300px
- **resolution**: string (default: 1080p) - Output resolution. 720p bills 210 credits/sec, 1080p bills 270 credits/sec
  Options: 720p, 1080p
- **aspect_ratio**: string (default: 16:9) - Aspect ratio for text-to-video and reference-to-video. Ignored with a single input image (its ratio is used)
  Options: 16:9, 9:16, 1:1, 4:3, 3:4
- **duration**: integer (default: 5) - Video duration in seconds (3-15). Billed per second of output
  Options: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
- **seed**: integer - Random seed for reproducible generation (0-2147483647)

## Examples

### Image-to-Video Animation
Animate a still image as the first frame of a video
```json
{
  "model": "alibaba/happyhorse-1.1",
  "input": {
    "prompt": "The animal prances across the branch",
    "images": [
      "https://example.com/animal.png"
    ],
    "duration": 5,
    "resolution": "1080p"
  }
}
```

### Cinematic Text-to-Video
Generate a video from a text description alone
```json
{
  "model": "alibaba/happyhorse-1.1",
  "input": {
    "prompt": "A majestic white horse gallops along a black-sand beach at golden hour, mane flowing in the wind, waves crashing in slow motion, cinematic tracking shot",
    "resolution": "1080p",
    "aspect_ratio": "16:9",
    "duration": 5
  }
}
```

## Response Format
```json
{
  "job_id": "abc123",
  "status": "pending | processing | completed | failed",
  "result": "URL or data (when completed)"
}
```

## Usage Flow
1. POST /predictions with model and input -> receive job_id
2. GET /predictions/{job_id} -> poll until status is completed or failed
3. Result contains output URL(s)

## Tips
- Billing is per second of output — iterate at 720p and 5 seconds, then switch to 1080p for the final render
- With multiple reference images, label them in the prompt: 'The character from [Image 1] walks through the scene in [Image 2]'
- A single input image locks the output to that image's aspect ratio — crop the image first if you need a different shape
- Input images must have an aspect ratio between 1:2.5 and 2.5:1 with each side at least 300px
- Use the seed parameter to reproduce a result you like while tweaking the prompt

## Documentation
https://replicate.com/alibaba/happyhorse-1.1