happyhorse-1.1-i2v API

Use the exact model ID happyhorse-1.1-i2v. The model field must match this page exactly.

Sample outputhappyhorse-1.1-i2vPOST /v1/videos5.2s

Parameters: duration=5resolution=1080pratio=16:9Input image

Prompt: One continuous take, no cuts. The braided steam keeps thickening until the ribbons lock into one coral and ultraviolet serpent that uncoils along the ceiling, drops down past the stools and pours out through the open door into the rain, the cook in the orange jacket stepping back to let it pass. The camera holds at counter height, then tracks with the serpent to the doorway and tilts to watch it leave. One hard tungsten bulb overhead stays the only warm source. Real weight and inertia, visible density in the steam, no text.

Request that produced this sample, with the input media URL replaced

{
  "model": "happyhorse-1.1-i2v",
  "prompt": "One continuous take, no cuts. The braided steam keeps thickening until the ribbons lock into one coral and ultraviolet serpent that uncoils along the ceiling, drops down past the stools and pours out through the open door into the rain, the cook in the orange jacket stepping back to let it pass. The camera holds at counter height, then tracks with the serpent to the doorway and tilts to watch it leave. One hard tungsten bulb overhead stays the only warm source. Real weight and inertia, visible density in the steam, no text.",
  "seconds": "5",
  "duration": 5,
  "resolution": "1080p",
  "ratio": "16:9",
  "aspect_ratio": "16:9",
  "image": "https://example.com/input-image.png"
}

Authentication and endpoint

Use a Modelflare API key with https://modelflare.dev/v1. The gateway entry point is POST /v1/videos.

HTTP

Authorization: Bearer YOUR_MODELFLARE_API_KEY

Create a task

bash

curl https://modelflare.dev/v1/videos \
  -H "Authorization: Bearer YOUR_MODELFLARE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "happyhorse-1.1-i2v",
    "input": {"prompt": "The cat runs across the grass as the camera follows smoothly.", "media": [{"type": "first_frame", "url": "https://example.com/cat.png"}]},
    "parameters": {"resolution": "1080P", "duration": 5, "watermark": false}
  }'

Poll and download

Save the task ID. Poll GET /v1/videos/{task_id} and download with GET /v1/videos/{task_id}/content. Result URLs may expire, so transfer the file promptly.

bash

curl https://modelflare.dev/v1/videos/TASK_ID \
  -H "Authorization: Bearer YOUR_MODELFLARE_API_KEY"

Request notes

HappyHorse uses input.prompt; choose the input.media shape that matches the t2v, i2v, or r2v model ID.

Request parameters

HappyHorse I2V places one first_frame image in input.media.

Field	Required	Notes
model	Yes	happyhorse-1.1-i2v
input.prompt	No	Optional motion and camera description, up to 5,000 non-Chinese or 2,500 Chinese characters
input.media[]	Yes	Exactly one first_frame; public URL or Base64 data URL, under 20 MB, minimum 300px sides, and 1:2.5–2.5:1 aspect ratio
parameters.resolution	No	720P / 1080P, default 1080P
parameters.ratio	No	Not supported; output follows the first-frame image ratio
parameters.duration	No	3–15 seconds, default 5
parameters.watermark	No	Whether to add the HappyHorse watermark
parameters.seed	No	Optional seed from 0 to 2,147,483,647

Input and output limits

I2V uses one first_frame image; accept a public URL or Base64 data URL under 20 MB with 300px minimum sides and a 1:2.5–2.5:1 aspect ratio, and approximately preserve the input ratio.

Errors and failed tasks

Invalid model parameters return a 4xx with a request ID. An asynchronous task can also enter failed after creation succeeds; use error_code and error_message from the poll response as the final task reason. Do not retry the same request with a different JSON shape.

Supported scope

This page covers Modelflare model generation and editing calls. Search or map enrichment, voice management, and element-library management are resource APIs outside this public model-call surface and are not required request fields.

Pricing and billing

This model uses per-second video billing. See the model pricing page for the current customer price, reference list price, and complete specification.

Note

This page documents Modelflare’s public interface; the fields and limits shown here are the current contract.