Extend Video - SlideVid API Documentation

Extend Video

curl --request POST \
  --url https://api.slidevid.ai/v1/project/create/extend-video \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "media": "media_video123",
  "prompt": "The camera slowly zooms out revealing a beautiful sunset over the ocean",
  "targetDuration": 4,
  "generateAudio": true
}
'

{
  "success": true,
  "data": {
    "videoId": "vid_extend_abc123xyz",
    "projectId": "proj_extend_abc123xyz",
    "status": "STARTED"
  }
}

POST

project

create

extend-video

Extend Video

curl --request POST \
  --url https://api.slidevid.ai/v1/project/create/extend-video \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "media": "media_video123",
  "prompt": "The camera slowly zooms out revealing a beautiful sunset over the ocean",
  "targetDuration": 4,
  "generateAudio": true
}
'

{
  "success": true,
  "data": {
    "videoId": "vid_extend_abc123xyz",
    "projectId": "proj_extend_abc123xyz",
    "status": "STARTED"
  }
}

Try it out! Use the API playground on the right to test the Extend Video endpoint directly.

Overview

Extend Video uses AI (Veo 3.1) to intelligently continue and extend your videos. Perfect for:

Creating longer content from short clips
Generating smooth video continuations
Extending storytelling sequences
Producing extended versions of marketing videos
Automating video length optimization

Extensions are generated in segments of 4-8 seconds each. The AI analyzes the last frame of your video and generates a seamless continuation based on your prompt.

Endpoint

POST /v1/project/create/extend-video

Required Fields

media

string

required

Media ID of the video to extend (as a string)

prompt

string

required

Describe how the AI should continue the video (1-2000 characters)Example: “The camera continues to zoom out, revealing a cityscape at sunset with birds flying across the sky”

Optional Fields

name

string

Custom name for the project (max 100 characters)

targetDuration

number

default:4

Total duration to extend in seconds (4-60 seconds, must be multiple of 4)

Minimum: 4 seconds
Maximum: 60 seconds
Default: 4 seconds

generateAudio

boolean

default:true

Whether to generate audio for the extended portion

webhook

string

Webhook URL for status notifications (max 500 characters, must be HTTPS)

metadata

object

Custom metadata object (max 5KB JSON)

Request Examples

Basic Video Extension

const response = await fetch('https://api.tryslidevid.ai/v1/project/create/extend-video', {
  method: 'POST',
  headers: {
    'x-api-key': process.env.SLIDEVID_API_KEY,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    media: 'media_video123',
    prompt: 'The camera slowly zooms out revealing a beautiful sunset over the ocean',
    targetDuration: 8,
    generateAudio: true
  })
});

const data = await response.json();
console.log('Video ID:', data.data.videoId);
console.log('Project ID:', data.data.projectId);

Extended Duration with Webhook

const extendVideoLonger = async () => {
  const response = await fetch('https://api.tryslidevid.ai/v1/project/create/extend-video', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.SLIDEVID_API_KEY,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      media: 'media_marketing_clip',
      prompt: 'The product rotates smoothly as the background transitions from blue to purple with subtle particle effects',
      targetDuration: 16, // 16 seconds extension
      generateAudio: true,
      webhook: 'https://yoursite.com/webhook',
      metadata: {
        campaignId: 'product-launch-2024',
        videoType: 'marketing'
      }
    })
  });

  return await response.json();
};

Multiple Extensions

const extendVideoMultiple = async () => {
  const response = await fetch('https://api.tryslidevid.ai/v1/project/create/extend-video', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.SLIDEVID_API_KEY,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      name: 'Extended Story Video',
      media: 'media_story_video',
      prompt: 'The scene continues with smooth camera movement, transitioning through different environments while maintaining visual consistency',
      targetDuration: 32, // Will be processed in 4 segments of 8 seconds each
      generateAudio: true
    })
  });

  return await response.json();
};

Response

{
  "success": true,
  "data": {
    "videoId": "vid_extend_abc123xyz",
    "projectId": "proj_extend_abc123xyz",
    "status": "STARTED"
  }
}

Webhook Notification

When your extended video is ready, we’ll POST to your webhook URL (if configured):

Webhook Payload

{
  "status": "COMPLETED",
  "data": {
    "videoId": "vid_extend_abc123xyz",
    "status": "COMPLETED",
    "url": "https://cdn.tryslidevid.ai/videos/abc123xyz.mp4",
    "shareUrl": "https://cdn.tryslidevid.ai/shared/abc123xyz.mp4",
    "metadata": {
      "projectId": "proj_extend_abc123xyz",
      "originalDuration": "5s",
      "extendedDuration": "13s"
    }
  },
  "message": "Video completed"
}

How It Works

Upload Source Video

Provide your source video that you want to extend

AI Analysis

Veo 3.1 analyzes the last frame and video motion patterns

Generate Extensions

AI generates extension segments (8 seconds each) based on your prompt

Seamless Concatenation

All segments are seamlessly concatenated with the source video

Final Output

Receive your extended video with smooth transitions

Best Practices

Clear Prompts

Describe the continuation clearly and specifically for best results

Match Style

Reference the visual style of your source video in the prompt

Realistic Durations

Start with 8-16 seconds to ensure quality, then scale up

Audio Consistency

Enable generateAudio for better continuity with the source

Prompt Writing Tips

Good Prompts

✅ “The camera continues to pan right, revealing a mountain range at golden hour with soft clouds drifting across the sky” ✅ “The dancer spins gracefully as the lighting shifts from warm orange to cool blue” ✅ “The product rotates smoothly on the pedestal while particles float upward in the background”

Avoid

❌ “Continue the video” (too vague) ❌ “Make it longer” (no direction) ❌ “Add random stuff” (unclear intent)

Error Handling

Error	Description	Solution
`media: A video is required`	Missing or invalid media ID	Provide a valid video media ID
`Media not found`	Media ID doesn’t exist	Check that the media ID is correct and exists
`Media is not a video`	Media is not a video type	Ensure the media ID points to a video, not an image
`prompt: Prompt is required`	Missing prompt	Provide a descriptive prompt for the extension
`targetDuration: Target duration must be at least 4 seconds`	Duration too short	Use minimum 4 seconds
`targetDuration: Target duration cannot exceed 60 seconds`	Duration too long	Use maximum 60 seconds
`aspectRatio: Invalid enum value`	Invalid aspect ratio	Use `ratio_9_16`, `ratio_16_9`, or `ratio_1_1`
`Not enough credits`	Insufficient credits	Top up your account credits

Processing Time

Extension processing time varies based on:

Target Duration: Longer extensions take more time (each 8-second segment ~2-3 minutes)
Audio Generation: Enabling audio adds processing time
Queue Load: Peak times may have longer waits

Typical processing times:

8 seconds: 2-3 minutes
16 seconds: 4-6 minutes
32 seconds: 8-12 minutes
60 seconds: 15-20 minutes

Next Steps

List Videos

View all your created videos

Video Details

Check your video processing status

Webhooks Guide

Learn how to handle webhook notifications

Examples

See more extend video examples

Authorizations

x-api-key

string

header

required

Body

application/json

media

string

required

Media ID from uploaded video

prompt

string

required

Describe how the AI should continue the video

Required string length: 1 - 2000

targetDuration

number

default:4

Total duration to extend in seconds (must be multiple of 4)

Required range: 4 <= x <= 60

generateAudio

boolean

default:true

Whether to generate audio for the extended portion

name

string

Custom name for the project

Maximum string length: 100

webhook

string

HTTPS URL for status notifications (max 500 characters)

Maximum string length: 500

metadata

object

Custom metadata object (max 5KB)

Response

Extend Video created successfully

success

boolean

data

object

Show child attributes

Add Captions Hook + Demo

​Overview

​Endpoint

​Required Fields

​Optional Fields

​Request Examples

​Basic Video Extension

​Extended Duration with Webhook

​Multiple Extensions

​Response

​Webhook Notification

​How It Works

​Best Practices

Clear Prompts

Match Style

Realistic Durations

Audio Consistency

​Prompt Writing Tips

​Good Prompts

​Avoid

​Error Handling

​Processing Time

​Next Steps

List Videos

Video Details

Webhooks Guide

Examples

Authorizations

Body

Response

Overview

Endpoint

Required Fields

Optional Fields

Request Examples

Basic Video Extension

Extended Duration with Webhook

Multiple Extensions

Response

Webhook Notification

How It Works

Best Practices

Prompt Writing Tips

Good Prompts

Avoid

Error Handling

Processing Time

Next Steps