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:
More details are available in our prompting guide.
The model supports:
Note: Video extension is only supported via Vertex AI.
Safety filters are applied to both input videos and generated content.
The client provides a convenient way to interact with the model API.
npm install --save @fal-ai/clientThe @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.
Set FAL_KEY as an environment variable in your runtime.
export FAL_KEY="YOUR_API_KEY"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);The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.
import { fal } from "@fal-ai/client";
fal.config({
credentials: "YOUR_FAL_KEY"
});When running code on the client-side (e.g. in a browser, mobile app or GUI applications), make sure to not expose your FAL_KEY. Instead, use a server-side proxy to make requests to the API. For more information, check out our server-side integration guide.
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",
});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,
});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);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.
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.
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.
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);The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).
Read more about file handling in our file upload guide.
prompt string* requiredThe text prompt describing how the video should be extended
aspect_ratio AspectRatioEnumThe aspect ratio of the generated video. Default value: "auto"
Possible enum values: auto, 16:9, 9:16
duration stringThe duration of the generated video. Default value: "7s"
negative_prompt stringA negative prompt to guide the video generation.
resolution stringThe resolution of the generated video. Default value: "720p"
generate_audio booleanWhether to generate audio for the video. Default value: true
seed integerThe seed for the random number generator.
auto_fix booleanWhether to automatically attempt to fix prompts that fail content policy or other validation checks by rewriting them.
safety_tolerance SafetyToleranceEnumThe safety tolerance level for content moderation. 1 is the most strict (blocks most content), 6 is the least strict. Default value: "4"
Possible enum values: 1, 2, 3, 4, 5, 6
Note: This property is only available through API calls.
video_url string* requiredURL 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,
"safety_tolerance": "4",
"video_url": "https://v3b.fal.media/files/b/0a8670fe/pY8UGl4_C452wOm9XUBYO_9ae04df8771c4f3f979fa5cabeca6ada.mp4"
}The extended video.
{
"video": {
"url": "https://v3b.fal.media/files/b/0a86711b/B_Z96VS4X9Dfd4M5ArB4H_c666e63f729f4a8fa1145c6727cef97d.mp4"
}
}url string* requiredThe URL where the file can be downloaded from.
content_type stringThe mime type of the file.
file_name stringThe name of the file. It will be auto-generated if not provided.
file_size integerThe size of the file in bytes.