Veo3.1 Fast Video Extend | AI Video Extension API

Veo 3.1 — Video Extend (Fast)

Veo 3.1 Video Extend (Fast) lets you quickly append a 7-second continuation to an existing Veo-generated video. You pass the previous output as video plus a new prompt, and the model returns one merged clip containing both the original segment and the new extension—optimised for low latency and faster iteration.

⚡ What makes the Fast endpoint different

Optimised for speed: Same continuation logic as standard Video Extend, but tuned for faster turnaround so you can iterate more quickly.
True continuation, not regeneration: Works only with Veo 3.1 outputs, preserving look, motion style, and aspect ratio.
Fixed extension block: Each call adds +7 seconds, and you can chain extensions up to 20 times.
Single merged deliverable: The API always returns one video file (input + extension) with a maximum length of 148 seconds.

🎯 Designed For

Rapid story development: Test different “next beats” on top of a strong base shot without re-generating the whole sequence.
Ad and social variations: Quickly create extended cuts, alternate endings, or extra moments for trailers, promos, and Shorts/Reels.
Fast production feedback loops: Respond to review notes by extending just the part that needs more room.

🧩 Input / Output Constraints

Input must be Veo-generated: Upload only videos that were created by Veo 3.1 (text-to-video or image-to-video).
Input limits:
Maximum input duration: 141 seconds
Supported aspect ratios: 16:9 or 9:16
Supported resolutions: 720p or 1080p
Extension limits:
Each run adds +7 seconds
Up to 20 extensions in a chain
Maximum final length (original + extensions): 148 seconds

Output: a single MP4 video at the same resolution and aspect ratio as the input clip.

🚀 How to Use

Generate a base clip with Veo 3.1 text-to-video or image-to-video.
Call Veo 3.1 — Video Extend (Fast) and pass that clip as video.
Write an extension prompt describing what should happen next:

Action (what characters or objects do)
Camera behaviour (pan, zoom, dolly, cut feel)
Mood and visual style (lighting, atmosphere, pacing)

Submit the job and download the merged extended video.
To continue the story, feed the new output back into the same endpoint (respecting the 148s cap).

✍️ Prompt Tips

Think of the prompt as a “next shot” or “next beat”:

action + camera + mood + continuity anchors

Example: “Continue from previous shot, camera slowly cranes up, the character walks toward the glowing city skyline, warm cinematic lighting, smooth motion.”

Mention what should stay consistent:
Main character, wardrobe, time of day, general colour palette.
If audio continuity matters, ensure the last second of the input clip has usable audio; the extension will build from that context.
Plan your narrative around:
7-second extension blocks, and
the 141s input / 148s total hard limits.

💰 Pricing

Flat, simple pricing:

$1.05 per run

Each run appends one 7-second fast extension to your clip and returns a new merged video.

Approximate cost per 7-second block:

≈ $0.15 per second of added footage.

🔁 More Model Options

/wan-2.5/video-extend Extend WAN 2.5 AI videos with smooth, style-consistent continuations, perfect for story-driven ads, trailers, and long-form generative video workflows.
google/veo3.1/video-extend Google Veo 3.1 Fast video extend rapidly adds high-quality extra segments to Veo-generated clips, ideal for Shorts, Reels, and other fast-turnaround AI video content.

Veo3.1 Fast Video Extend API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/google/veo3.1-fast/video-extend with your input as JSON. The endpoint returns a prediction id; poll the prediction endpoint until status flips to completed, then read the output URL from data.outputs[0]. Examples for Veo3.1 Fast Video Extend below.

HTTP example

# Submit the prediction
curl -X POST "https://api.wavespeed.ai/api/v3/google/veo3.1-fast/video-extend" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY" \
  -d '{
    "video": "https://example.com/your-input.mp4",
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "resolution": "1080p",
    "negative_prompt": "blurry, low quality, distorted",
    "seed": 0
}'

# Response includes a prediction id. Poll for the result:
curl -X GET "https://api.wavespeed.ai/api/v3/predictions/{request_id}/result" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY"

# When status is "completed", read the output from data.outputs[0].

Node.js example

// npm install wavespeed
const WaveSpeed = require('wavespeed');

const client = new WaveSpeed(); // reads WAVESPEED_API_KEY from env

const result = await client.run("google/veo3.1-fast/video-extend", {
        "video": "https://example.com/your-input.mp4",
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "resolution": "1080p",
        "negative_prompt": "blurry, low quality, distorted",
        "seed": 0
});

console.log(result.outputs[0]); // → URL of the generated output

Python example

# pip install wavespeed
import wavespeed

output = wavespeed.run(
    "google/veo3.1-fast/video-extend",
    {
    "video": "https://example.com/your-input.mp4",
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "resolution": "1080p",
    "negative_prompt": "blurry, low quality, distorted",
    "seed": 0
}
)

print(output["outputs"][0])  # → URL of the generated output

Veo3.1 Fast Video Extend API — Frequently asked questions

What is the Veo3.1 Fast Video Extend API?

Veo3.1 Fast Video Extend is a Google model for video extension, exposed as a REST API on WaveSpeedAI. Extend Veo 3.1 videos in 7-second steps with the Fast endpoint—quick, coherent continuation that preserves style and motion, output as a single merged clip. Ready-to-use REST inference API, best performance, no coldstarts, affordable pricing. You can call it programmatically or try it from the playground above.

How do I call the Veo3.1 Fast Video Extend API?

POST your input parameters to the model's REST endpoint (shown in the API tab of this playground) with your WaveSpeedAI API key in the Authorization header. Submission returns a prediction ID; poll the prediction endpoint until status flips to "completed", then read the output URL from the result. The playground generates a ready-to-paste code sample in Python, JavaScript, or cURL for whatever inputs you've set. Full request/response shape is documented at https://wavespeed.ai/docs/docs-api/google/google-veo3.1-fast-video-extend.

How much does Veo3.1 Fast Video Extend cost per run?

Veo3.1 Fast Video Extend starts at $1.05 per run. That figure is the base price — the final charge scales with the parameters you set in the form (output size, length, count, references, or whatever knobs this model exposes), so a higher-quality or larger output costs more than a minimal one. The exact cost for your current input is shown live next to the Generate button before you submit, and the actual per-call charge is recorded on the prediction afterwards.

What inputs does Veo3.1 Fast Video Extend accept?

Key inputs: `prompt`, `video`, `resolution`, `seed`, `negative_prompt`. The full JSON schema (types, defaults, allowed values) is rendered above the Generate button and mirrored in the API reference at https://wavespeed.ai/docs/docs-api/google/google-veo3.1-fast-video-extend.

How long does Veo3.1 Fast Video Extend take to generate?

Average end-to-end generation time on WaveSpeedAI is around 177 seconds per request — measured across recent runs. Queue time scales with global demand; live status is visible in the prediction record.

Can I use Veo3.1 Fast Video Extend outputs commercially?

Commercial usage rights depend on the model's license, set by its provider (Google). The license summary appears on the model card above; see WaveSpeedAI's Terms of Service for platform-level conditions.

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