API reference · Google

google/veo3.1/fast/video-extend

Integrate this model through SandBase's unified API, with production-ready schemas and examples.

VIDEOAsyncOpen model

Production endpoint

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OpenAI-compatible endpoint with unified authentication and usage tracking.

POSThttps://api.sandbase.ai/v1/run

Model IDgoogle/veo3.1/fast/video-extend

Input Schema

8 parameters · 2 required · 6 optional

Parameter	Type	Required	Description
`video`	string	Required	Video to extend: MP4 at 24 fps, 720p (for example a Veo output). Veo appends the requested duration to it.
`prompt`	string	Required	The text prompt describing how the video should be extended · Max length: 20000
`seed`	integer	Optional	Random seed for more reproducible results. · Min: 0 · Max: 4294967295
`duration`	integer	Optional	Length of the generated extension in seconds. · Options: 7 · Default: 7 7
`resolution`	string	Optional	Output resolution. Extensions are generated at 720p. · Options: 720p · Default: "720p" 720p
`aspect_ratio`	string	Optional	Output aspect ratio. `auto` follows the input. · Options: auto, 16:9, 9:16 · Default: "auto" auto16:99:16
`generate_audio`	boolean	Optional	Generate synchronized audio. Videos without audio are cheaper. · Default: true
`negative_prompt`	string	Optional	What to avoid in the video.

Output Schema

Field	Type	Description
`id`	string	Unique identifier for the generation task
`status`	string	Task status: pending, running, completed, failed, timeout
`model`	string	Model used for the generation
`outputs`	array	Array of output items
`outputs[].url`	string	URL of the generated artifact
`outputs[].content_type`	string	MIME type (e.g. image/png, video/mp4)
`error`	object \| null	Error details if failed, null on success
`error.type`	string	Machine-readable error type code
`error.message`	string	Human-readable error description

Async Workflow

This model uses asynchronous execution. Submit a request and poll for the result.

Submit — POST to /v1/run, receive an id
Poll — GET /v1/run/{id} until status is completed, failed, or timeout
Retrieve — Read outputs from the completed response

Code Examples

Ready-to-run snippets

const apiKey = process.env.SANDBASE_API_KEY;
const response = await fetch("https://api.sandbase.ai/v1/run", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "google/veo3.1/fast/video-extend",
    "prompt": "Continue the scene naturally, maintaining the same style and motion.",
    "duration": 7,
    "resolution": "720p",
    "aspect_ratio": "auto",
    "generate_audio": true
  }),
});

if (!response.ok) throw new Error(await response.text());
let result = await response.json();
for (let attempt = 0; attempt < 120 && !["completed", "failed", "timeout"].includes(result.status); attempt++) {
  await new Promise((resolve) => setTimeout(resolve, 2_000));
  const poll = await fetch(`https://api.sandbase.ai/v1/run/${result.id}`, {
    headers: { Authorization: `Bearer ${apiKey}` },
  });
  if (!poll.ok) throw new Error(await poll.text());
  result = await poll.json();
}
if (result.status !== "completed") throw new Error(`Generation ended: ${result.status}`);
console.log(result);

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