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Veo 3.1 Fast Video to Video

fal-ai/veo3.1/fast/extend-video
Extend Veo-Created Videos up to 30 seconds
Inference
Commercial use
Partner
Schema
LLMs
PlaygroundAPI

About

Extend a video using Google's Veo 3.1 Fast model.

This endpoint takes an existing video and extends it based on a text prompt. The prompt should describe how the video should continue or be extended.

Include in your prompt:

  • Action: What should happen next in the video
  • Style: Maintain or transition to a specific visual style
  • Camera motion (optional): How the camera should move
  • Ambiance (optional): Desired mood and atmosphere

More details are available in our prompting guide.

The model supports:

  • Input videos up to 8 seconds in length
  • 720p or 1080p resolution
  • 16:9 or 9:16 aspect ratio
  • Natural motion continuation

Note: Video extension is only supported via Vertex AI.

Safety filters are applied to both input videos and generated content.

1. Calling the API#

Install the client#

The client provides a convenient way to interact with the model API.

npm install --save @fal-ai/client

Setup your API Key#

Set FAL_KEY as an environment variable in your runtime.

export FAL_KEY="YOUR_API_KEY"

Submit a request#

The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.

import { fal } from "@fal-ai/client";

const result = await fal.subscribe("fal-ai/veo3.1/fast/extend-video", {
  input: {
    prompt: "Continue the scene naturally, maintaining the same style and motion.",
    video_url: "https://v3b.fal.media/files/b/0a8670fe/pY8UGl4_C452wOm9XUBYO_9ae04df8771c4f3f979fa5cabeca6ada.mp4"
  },
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});
console.log(result.data);
console.log(result.requestId);

2. Authentication#

The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.

API Key#

In case your app is running in an environment where you cannot set environment variables, you can set the API Key manually as a client configuration.
import { fal } from "@fal-ai/client";

fal.config({
  credentials: "YOUR_FAL_KEY"
});

3. Queue#

Submit a request#

The client API provides a convenient way to submit requests to the model.

import { fal } from "@fal-ai/client";

const { request_id } = await fal.queue.submit("fal-ai/veo3.1/fast/extend-video", {
  input: {
    prompt: "Continue the scene naturally, maintaining the same style and motion.",
    video_url: "https://v3b.fal.media/files/b/0a8670fe/pY8UGl4_C452wOm9XUBYO_9ae04df8771c4f3f979fa5cabeca6ada.mp4"
  },
  webhookUrl: "https://optional.webhook.url/for/results",
});

Fetch request status#

You can fetch the status of a request to check if it is completed or still in progress.

import { fal } from "@fal-ai/client";

const status = await fal.queue.status("fal-ai/veo3.1/fast/extend-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
  logs: true,
});

Get the result#

Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.

import { fal } from "@fal-ai/client";

const result = await fal.queue.result("fal-ai/veo3.1/fast/extend-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);

4. Files#

Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.

Data URI (base64)#

You can pass a Base64 data URI as a file input. The API will handle the file decoding for you. Keep in mind that for large files, this alternative although convenient can impact the request performance.

Hosted files (URL)#

You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.

Uploading files#

We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.

import { fal } from "@fal-ai/client";

const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);

Read more about file handling in our file upload guide.

5. Schema#

Input#

prompt string* required

The text prompt describing how the video should be extended

aspect_ratio AspectRatioEnum

The aspect ratio of the generated video. Default value: "auto"

Possible enum values: auto, 16:9, 9:16

duration DurationEnum

The duration of the generated video. Default value: "7s"

Possible enum values: 7s

resolution ResolutionEnum

The resolution of the generated video. Default value: "720p"

Possible enum values: 720p

generate_audio boolean

Whether to generate audio for the video. Default value: true

auto_fix boolean

Whether to automatically attempt to fix prompts that fail content policy or other validation checks by rewriting them.

video_url string* required

URL of the video to extend. The video should be 720p or 1080p resolution in 16:9 or 9:16 aspect ratio.

{
  "prompt": "Continue the scene naturally, maintaining the same style and motion.",
  "aspect_ratio": "auto",
  "duration": "7s",
  "resolution": "720p",
  "generate_audio": true,
  "video_url": "https://v3b.fal.media/files/b/0a8670fe/pY8UGl4_C452wOm9XUBYO_9ae04df8771c4f3f979fa5cabeca6ada.mp4"
}

Output#

video File* required

The extended video.

{
  "video": {
    "url": "https://v3b.fal.media/files/b/0a86711b/B_Z96VS4X9Dfd4M5ArB4H_c666e63f729f4a8fa1145c6727cef97d.mp4"
  }
}

Other types#

File#

url string* required

The URL where the file can be downloaded from.

content_type string

The mime type of the file.

file_name string

The name of the file. It will be auto-generated if not provided.

file_size integer

The size of the file in bytes.

file_data string

File data

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