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Last updated September 7, 2026

Submit an async task for minimax/minimax-h3 through the unified entry point. Flat request body.

Submit a minimax/minimax-h3 video task through the unified entry point. The body is flat: prompt, material and parameters all at the top level.

POSThttps://gateway.amux.ai/v1/tasks

Authorization

header
AuthorizationstringRequired

Bearer <your Amux key> Your Amux API key.

Request

application/json
modelstringRequired

Always minimax/minimax-h3. The manufacturer-free minimax-h3 works too, case-insensitively.

promptstringRequired

What to generate. Required, up to 7000 characters.

mediaarray<object>

Input material; each item states its purpose via type. This model accepts: first_frame / last_frame / reference_image / reference_video / reference_audio. Public https URLs only.

›mediaarray<object>
type"first_frame" | "last_frame" | "reference_image" | "reference_video" | "reference_audio"Required

What this material is for.

urlstringRequired

A public https URL. The model fetches it; Amux never does.

resolution"768P" | "2K"Default "768P"

Output resolution tier. This is a pricing dimension -- the per-second rate follows it. This model has only 768P / 2K. The upstream marks it required, so when you omit it we send 768P and say so in the task's notes.

durationintegerDefault 4

Output length in seconds, an integer from 4 to 15. This model has no automatic duration (-1). The upstream marks it required, so when you omit it we send 5 and note it.

aspect_ratio"adaptive" | "21:9" | "16:9" | "4:3" | "1:1" | "3:4" | "9:16"

Aspect ratio. adaptive cannot be used for text-only generation (no material to follow); when omitted we send 16:9 and note it.

watermarkbooleanDefault false

Whether to stamp an AIGC watermark on the output.

webhook_urlstring

Called back when the task reaches a terminal state. This is the same thing as Amux's webhook_url — only the name differs; the payload matches the unified endpoint exactly. Must be a deliverable public https URL.

Response

200response

Accepted. Take id to GET /v1/tasks/{id} and poll.

400response

Invalid parameters, a missing prompt, or a material role this model does not accept.

402response

Available balance does not cover the reservation.

503response

No provider can currently serve this model.

Relationship to the native shape

Billing, routing and reservation are identical; only the wire format differs:

Native shapeThis one
Prompt and materialone content[] arrayprompt plus media[]
Material purposerolemedia[].type
Material URLnested image_url.urlflat media[].url
Ratio parameterratioaspect_ratio
Usage and cost on retrievalabsentpresent

Accepted values

ParameterThis model
resolution768P / 2K
durationan integer from 4 to 15
aspect_ratioadaptive (needs material) / 21:9 / 16:9 / 4:3 / 1:1 / 3:4 / 9:16
media[].typeone first frame, one last frame, nine reference images, three reference videos and three reference audio clips

Note that prompt is required, and text-only generation needs a concrete aspect_ratio — when you omit it we send 16:9 and say so in notes.

Billing

This model bills for input material: reference images per image and reference video by its input duration (at the output tier's rate); reference audio is free.

The cost in the example (0.36) is the price of 768P x 4s plus one reference image.

Submitting returns a task ID

Take id to the retrieval endpoint and poll. Ten minutes or more is normal for a video — do not hold an HTTP connection open for it.

cURL
curl https://gateway.amux.ai/v1/tasks \
  -H "Authorization: Bearer $AMUX_API_KEY" \
  -d '{
    "model": "minimax/minimax-h3",
    "prompt": "A ginger cat running through fresh snow, slow motion",
    "resolution": "768P",
    "duration": 4,
    "aspect_ratio": "16:9"
  }'
{
  "id": "task_01M1VD9E8WRYVBR7ES10SNQQQT",
  "status": "queued",
  "model": "minimax/minimax-h3",
  "created_at": "<string>",
  "output": {
    "images": [
      {}
    ],
    "videos": [
      {
        "index": 0,
        "url": "<string>"
      }
    ]
  },
  "usage": {
    "input_tokens": 0,
    "output_tokens": 0,
    "total_tokens": 0,
    "output_video_seconds": 0
  },
  "cost": "0.36",
  "notes": [
    "<string>"
  ],
  "error": {
    "message": "<string>",
    "code": "<string>"
  }
}