Veo 3.1 Fast

Use veo3.1-fast to create video output. This page contains the complete request needed for this model.

Model facts

Property	Value
Model ID	`veo3.1-fast`
Endpoint	`POST /api/v1/generation/create`
Output	Video
Modes	text-to-video, image-to-video
Pricing	View current pricing

Minimal request


curl -X POST https://api.api-stock.com/api/v1/generation/create \
  -H "Authorization: Bearer $API_STOCK_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "veo3.1-fast",
  "input": {
    "prompt": "A cinematic scene with soft natural light",
    "aspectRatio": "16:9"
  }
}'

The create response contains a task ID:


{
  "code": 200,
  "data": {
    "taskId": "019ca881-9503-7270-a560-f00fc2b15785",
    "status": "not_started",
    "createdAt": "2026-08-22T12:00:00.000Z"
  }
}

Parameters

Parameters belong inside the top-level input object. Unknown fields are rejected.

Parameter	Type	Required	Default	Description
`prompt`	string	Yes	—	User’s prompt
`aspectRatio`	“16:9” \| “9:16”	No	`"16:9"`	Aspect ratio
`urls`	string[]	No	—	Image URLs for video generation
`resolution`	“720p” \| “1080p” \| “4k”	No	`"1080p"`	Video resolution quality
`generationType`	“frame” \| “reference”	No	—	Generation type for VEO3 model

Modes

Minimal generation


{
  "model": "veo3.1-fast",
  "input": {
    "prompt": "A cinematic scene with soft natural light",
    "aspectRatio": "16:9"
  }
}

With urls


{
  "model": "veo3.1-fast",
  "input": {
    "prompt": "A cinematic scene with soft natural light",
    "aspectRatio": "16:9",
    "urls": [
      "https://example.com/input.jpg"
    ]
  }
}

Constraints

aspectRatio: allowed: 16:9, 9:16.
resolution: allowed: 720p, 1080p, 4k.
generationType: allowed: frame, reference.

Invalid types, unsupported enum values, out-of-range numbers, and missing required fields return HTTP 400 with error.code: "invalid_input". Correct the request rather than retrying it unchanged.

Result

Poll the task or provide a top-level webhook URL in the create request:


curl https://api.api-stock.com/api/v1/task/status/$TASK_ID \
  -H "Authorization: Bearer $API_STOCK_KEY"

A successful media task returns one or more files:


{
  "code": 200,
  "data": {
    "taskId": "019ca881-9503-7270-a560-f00fc2b15785",
    "status": "finished",
    "files": [
      {
        "fileUrl": "https://storage.api-stock.com/result.mp4",
        "fileType": "video"
      }
    ],
    "createdTime": "2026-08-22T12:00:00.000Z"
  }
}

See Tasks and webhooks for terminal statuses, retries and webhook delivery.