Video extend

Video extend takes a clip you already have and continues it. The result is your clip followed by the new seconds, as one MP4.

Model	Endpoint	Resolutions	Added duration	Audio
Video Fast Extend 1.1	`POST /v1/video-fast/v1.1/video-extend`	480p, 720p, 1080p	3–30 s	`generate_audio`

Create a task

curl https://api.fiveapi.ai/v1/video-fast/v1.1/video-extend \
  -H "Authorization: Bearer $FIVEAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://assets.example.com/inputs/clip.mp4",
    "prompt": "the camera keeps panning right across the skyline as the city lights come on",
    "duration": 5,
    "resolution": "720p",
    "generate_audio": true,
    "webhook_url": "https://hooks.example.com/fiveapi"
  }'

import os
import requests

task = requests.post(
    "https://api.fiveapi.ai/v1/video-fast/v1.1/video-extend",
    headers={"Authorization": f"Bearer {os.environ['FIVEAPI_API_KEY']}"},
    json={
        "video_url": "https://assets.example.com/inputs/clip.mp4",
        "prompt": "the camera keeps panning right across the skyline as the city lights come on",
        "duration": 5,
        "resolution": "720p",
        "generate_audio": True,
        "webhook_url": "https://hooks.example.com/fiveapi",
    },
    timeout=30,
).json()
print(task["id"], task["status"])

const res = await fetch("https://api.fiveapi.ai/v1/video-fast/v1.1/video-extend", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.FIVEAPI_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    video_url: "https://assets.example.com/inputs/clip.mp4",
    prompt: "the camera keeps panning right across the skyline as the city lights come on",
    duration: 5,
    resolution: "720p",
    generate_audio: true,
    webhook_url: "https://hooks.example.com/fiveapi",
  }),
});
const task = await res.json();
console.log(task.id, task.status);

Parameters

Field	Required	Description
`video_url`	yes	Public HTTPS URL of an MP4 or MOV clip: 360–2,000 px per side, at most 500 MB.
`prompt`	yes	How the video continues, up to 2,000 characters.
`duration`	yes	Seconds to add after the clip, 3–30.
`resolution`	yes	`480p`, `720p` or `1080p`.
`start_time`, `end_time`	no	A window of the clip to continue from, in seconds. Send both or neither; `end_time` must be greater than `start_time`. Default: the whole clip.
`generate_audio`	no	`true` generates audio for the new part that matches the clip. Default `false`.
`prompt_expansion`	no	`none`, `basic` or `advanced` (default).
`webhook_url`, `metadata`	no	See Webhooks and Tasks.

Duration rules

The clip, or the window you select with start_time and end_time, must be 2–30 seconds long.
The clip plus the added seconds may not exceed 30 seconds. For example, a 10-second clip can be extended by at most 20 seconds.
The result contains the clip followed by the continuation, so output.video.duration is at least duration.

Use a window to continue from a specific part of a longer video:

{
  "video_url": "https://assets.example.com/inputs/long-take.mp4",
  "start_time": 12,
  "end_time": 20,
  "prompt": "the runner crosses the finish line and raises both arms",
  "duration": 6,
  "resolution": "720p"
}

Tips for good results

Continue the action that is already happening. The best extensions follow the motion and camera movement at the end of the clip.
End the window on a clean frame. A frame without motion blur or a scene cut gives the model a stable start.

Get started

Core concepts

Guides

Build with AI

Resources

Create a task

Parameters

Duration rules

Tips for good results

​Create a task

​Parameters

​Duration rules

​Tips for good results

Create a task

Parameters

Duration rules

Tips for good results