HappyHorse 1.0 Reference to Video: Image-to-Video

Happy Horse 1.0 Reference to Video generates video from 1-9 reference images, with selectable 720p/1080p resolution. Happy Horse 1.0 Reference to Video - generate expressive video clips conditioned on 1-9 reference images plus a text prompt. Selectable output resolution (720p/1080p) - price scales with the resolution chosen.

Interactive model controls

Happy Horse 1.0 Reference to Video - generate expressive video clips conditioned on 1-9 reference images plus a text prompt. Selectable output resolution (720p/1080p) - price scales with the resolution chosen.

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Overview

About this model

Updated Sep 11, 2026

Happy Horse 1.0 Reference to Video generates expressive video clips conditioned on 1-9 reference images plus a text prompt, at your choice of 720p or 1080p output resolution. Reference multiple images in your prompt (e.g. "@image1 riding @image2") to compose scenes that combine characters, objects, and settings from separate source images.

A single resolution parameter lets you draft cheaply at 720p and switch to 1080p for final output on the same endpoint.

1Multi-subject composition: combine a character and an object/vehicle from separate reference images into one scene

2Character-consistent video: keep a character's appearance consistent across a generated video using a reference photo

3Product-in-scene video: place a product reference image into a generated environment

4Concept mashups: blend visual elements from multiple references into a single coherent video

5Marketing creative: generate branded video content referencing product/character assets

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Pricing & Value

Cost analysis

Provider	Cost	Notes
muapiapp	$0.21–$0.42/sec (720p–1080p)	Simple per-second, resolution-scaled pricing with no subscriptions. Pick 720p for cost-effective drafts or 1080p for premium output, on the same endpoint.

muapiapp$0.21–$0.42/sec (720p–1080p)

Simple per-second, resolution-scaled pricing with no subscriptions. Pick 720p for cost-effective drafts or 1080p for premium output, on the same endpoint.

** Competitor pricing is estimated based on similar model architectures and usage tiers.

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Technical Details

Configuration schema

Parameter	Type	Description	Default
Prompt	string	Text description of the desired video. Up to 5,000 non-Chinese (or 2,500 Chinese) characters.	`Use @image1 riding inside @image2 at extreme speed through a massive supermarket. The rocket cart blasts through aisles, launches over checkout counters, and sends products exploding everywhere while the camera chases closely behind through the chaos.`
Resolution	Enum (2 options)	Output resolution. Price scales with resolution: 720p is cheaper, 1080p is more expensive.	`720p`
Reference Images	array	1-9 reference image URLs. JPEG/PNG/WEBP, >=400px shortest side, <=10 MB each.	`https://d3adwkbyhxyrtq.cloudfront.net/webassets/videomodels/happy-horse-1-reference-to-video-720p-1.jpg`
Aspect Ratio	Enum (5 options)	Output video aspect ratio.	`16:9`
Duration (seconds)	int	Video duration in seconds.	`5`
Seed	int	Optional random seed for reproducibility (0-2147483647).	`0`

Promptstring

Text description of the desired video. Up to 5,000 non-Chinese (or 2,500 Chinese) characters.

Default Value

Use @image1 riding inside @image2 at extreme speed through a massive supermarket. The rocket cart blasts through aisles, launches over checkout counters, and sends products exploding everywhere while the camera chases closely behind through the chaos.

ResolutionEnum (2 options)

Output resolution. Price scales with resolution: 720p is cheaper, 1080p is more expensive.

Default Value720p

Reference Imagesarray

1-9 reference image URLs. JPEG/PNG/WEBP, >=400px shortest side, <=10 MB each.

Default Valuehttps://d3adwkbyhxyrtq.cloudfront.net/webassets/videomodels/happy-horse-1-reference-to-video-720p-1.jpg

Aspect RatioEnum (5 options)

Output video aspect ratio.

Default Value16:9

Duration (seconds)int

Video duration in seconds.

Default Value5

Seedint

Optional random seed for reproducibility (0-2147483647).

Default Value0

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Implementation Guide

Developer documentation

Provide 1-9 reference image URLs in images_list (JPEG/PNG/WEBP, ≥400px shortest side, ≤10MB each).
Write a prompt referencing the images by position (e.g. "@image1 riding @image2 through a city").
Set resolution to "720p" (cheaper, default) or "1080p" (premium output).
Select aspect ratio, duration (3-15s), and optional seed for reproducibility.
Submit your request—the model composes a video from your references at the selected resolution.

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Common Questions

Frequently asked

What is the cost of Happy Horse 1.0 Reference to Video?

Happy Horse 1.0 Reference to Video costs $0.21/sec at 720p (default) or $0.42/sec at 1080p on muapi. A 5-second 720p clip costs $1.05; the same clip at 1080p costs $2.10.

How do I choose the resolution?

Pass `resolution: "720p"` (default) or `resolution: "1080p"` in your request body — both are served by the same endpoint.

How many reference images can I use?

1 to 9 images. Reference each one in your prompt via @image1 through @image9, matching the order in `images_list`.

Can I use a fixed seed for reproducibility?

Yes, pass an integer `seed` (0-2147483647) to get more consistent results across runs with the same prompt/references.

What happened to the dedicated 720p/1080p endpoints?

They still work exactly as before, unchanged, for existing integrations. This unified endpoint is the new recommended way to access both resolutions through one integration.