alibaba/happy-horse/reference-to-video

Run Happy Horse 1.0: Reference to Video API

Generate a 1080p video with synchronized native audio from a text prompt and 1–9 reference images. Subject consistency is maintained across the clip using character tokens in your prompt.

Model ID: alibaba/happy-horse/reference-to-video
Provider: fal.ai
Commercial rights: Full commercial rights on all outputs

How it works

Supply between 1 and 9 reference images via image_urls. In your prompt, refer to each subject as character1, character2, ... character9 — the order matches the order of your image_urls array.

For example, two reference images of people could be prompted as:

"A dance battle between character1 and character2, cinematic lighting, smooth camera movement."

Specifications

Pricing

A 10-second clip at 1080p costs $2.80.

Quickstart

Install

JavaScript:

bash
npm install @fal-ai/client

Python:

bash
pip install fal-client

Set your API key

bash
export FAL_KEY="YOUR_API_KEY"

Submit a request

JavaScript:

js
import { fal } from "@fal-ai/client";

const result = await fal.subscribe("alibaba/happy-horse/reference-to-video", {
  input: {
    prompt: "A dance battle between character1 and character2, cinematic lighting, smooth camera movement.",
    image_urls: [
      "https://example.com/person-a.jpg",
      "https://example.com/person-b.jpg",
    ],
    aspect_ratio: "16:9",
    resolution: "1080p",
    duration: 5,
  },
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});

console.log(result.data.video.url);

Python:

python
import fal_client

def on_queue_update(update):
    if isinstance(update, fal_client.InProgress):
        for log in update.logs:
            print(log["message"])

result = fal_client.subscribe(
    "alibaba/happy-horse/reference-to-video",
    arguments={
        "prompt": "A dance battle between character1 and character2, cinematic lighting, smooth camera movement.",
        "image_urls": [
            "https://example.com/person-a.jpg",
            "https://example.com/person-b.jpg",
        ],
        "aspect_ratio": "16:9",
        "resolution": "1080p",
        "duration": 5,
    },
    with_logs=True,
    on_queue_update=on_queue_update,
)

print(result["video"]["url"])

Note: Reference images must be publicly accessible URLs. Use the storage helpers below if you need to upload local files first.

Input parameters

Output

json
{
  "video": {
    "url": "https://...",
    "content_type": "video/mp4",
    "file_name": "output.mp4",
    "file_size": 4404019,
    "width": 1920,
    "height": 1080,
    "fps": 24,
    "duration": 5.0,
    "num_frames": 120
  },
  "seed": 1234567
}

Queue API (long-running requests)

For clips longer than a few seconds, use the queue API to avoid blocking.

JavaScript:

js
import { fal } from "@fal-ai/client";

// Submit
const { request_id } = await fal.queue.submit("alibaba/happy-horse/reference-to-video", {
  input: {
    prompt: "character1 walks through a sunlit forest, cinematic.",
    image_urls: ["https://example.com/person-a.jpg"],
    duration: 15,
    resolution: "1080p",
  },
  webhookUrl: "https://your-server.com/webhook",
});

// Poll status
const status = await fal.queue.status("alibaba/happy-horse/reference-to-video", {
  requestId: request_id,
  logs: true,
});

// Fetch result once complete
const result = await fal.queue.result("alibaba/happy-horse/reference-to-video", {
  requestId: request_id,
});

console.log(result.data.video.url);

Python:

python
import fal_client

# Submit
handler = fal_client.submit(
    "alibaba/happy-horse/reference-to-video",
    arguments={
        "prompt": "character1 walks through a sunlit forest, cinematic.",
        "image_urls": ["https://example.com/person-a.jpg"],
        "duration": 15,
        "resolution": "1080p",
    },
    webhook_url="https://your-server.com/webhook",
)

request_id = handler.request_id

# Poll status
status = fal_client.status("alibaba/happy-horse/reference-to-video", request_id, with_logs=True)

# Fetch result once complete
result = fal_client.result("alibaba/happy-horse/reference-to-video", request_id)

print(result["video"]["url"])

Uploading files

If your reference images aren't already hosted, upload them before submitting.

JavaScript:

js
import { fal } from "@fal-ai/client";

const file = new File([imageBuffer], "reference.jpg", { type: "image/jpeg" });
const url = await fal.storage.upload(file);

// Use `url` in your image_urls array

Python:

python
import fal_client

url = fal_client.upload_file("path/to/your/reference.jpg")

# Use `url` in your image_urls list

Client-side usage

Security: Never expose your FAL_KEY in browser or mobile code. Route requests through a server-side proxy: set FAL_KEY as a server environment variable and have your frontend call your own backend endpoint, which forwards the request to fal.

Links

• HappyHorse-1.0
• fal.ai documentation