Add Captions

Add Captions

curl --request POST \
  --url https://api.slidevid.ai/v1/project/create/add-captions \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "media": "media_abc123",
  "language": "en",
  "caption": {
    "preset": "beast",
    "alignment": "bottom"
  },
  "addStickers": true,
  "musicId": "upbeat_001"
}
'

import requests

url = "https://api.slidevid.ai/v1/project/create/add-captions"

payload = {
    "media": "media_abc123",
    "language": "en",
    "caption": {
        "preset": "beast",
        "alignment": "bottom"
    },
    "addStickers": True,
    "musicId": "upbeat_001"
}
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    media: 'media_abc123',
    language: 'en',
    caption: {preset: 'beast', alignment: 'bottom'},
    addStickers: true,
    musicId: 'upbeat_001'
  })
};

fetch('https://api.slidevid.ai/v1/project/create/add-captions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.slidevid.ai/v1/project/create/add-captions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'media' => 'media_abc123',
    'language' => 'en',
    'caption' => [
        'preset' => 'beast',
        'alignment' => 'bottom'
    ],
    'addStickers' => true,
    'musicId' => 'upbeat_001'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.slidevid.ai/v1/project/create/add-captions"

	payload := strings.NewReader("{\n  \"media\": \"media_abc123\",\n  \"language\": \"en\",\n  \"caption\": {\n    \"preset\": \"beast\",\n    \"alignment\": \"bottom\"\n  },\n  \"addStickers\": true,\n  \"musicId\": \"upbeat_001\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("x-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.slidevid.ai/v1/project/create/add-captions")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"media\": \"media_abc123\",\n  \"language\": \"en\",\n  \"caption\": {\n    \"preset\": \"beast\",\n    \"alignment\": \"bottom\"\n  },\n  \"addStickers\": true,\n  \"musicId\": \"upbeat_001\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.slidevid.ai/v1/project/create/add-captions")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"media\": \"media_abc123\",\n  \"language\": \"en\",\n  \"caption\": {\n    \"preset\": \"beast\",\n    \"alignment\": \"bottom\"\n  },\n  \"addStickers\": true,\n  \"musicId\": \"upbeat_001\"\n}"

response = http.request(request)
puts response.read_body

{
  "success": true,
  "data": {
    "videoId": "vid_caption_abc123xyz",
    "projectId": "proj_caption_abc123xyz",
    "status": "STARTED"
  }
}

{
  "success": false,
  "message": "media: Media ID is required"
}

{
  "success": false,
  "message": "media: Media not found"
}

{
  "success": false,
  "message": "musicId: Music \"invalid_music\" not found."
}

POST

project

create

add-captions

Add Captions

curl --request POST \
  --url https://api.slidevid.ai/v1/project/create/add-captions \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "media": "media_abc123",
  "language": "en",
  "caption": {
    "preset": "beast",
    "alignment": "bottom"
  },
  "addStickers": true,
  "musicId": "upbeat_001"
}
'

import requests

url = "https://api.slidevid.ai/v1/project/create/add-captions"

payload = {
    "media": "media_abc123",
    "language": "en",
    "caption": {
        "preset": "beast",
        "alignment": "bottom"
    },
    "addStickers": True,
    "musicId": "upbeat_001"
}
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    media: 'media_abc123',
    language: 'en',
    caption: {preset: 'beast', alignment: 'bottom'},
    addStickers: true,
    musicId: 'upbeat_001'
  })
};

fetch('https://api.slidevid.ai/v1/project/create/add-captions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.slidevid.ai/v1/project/create/add-captions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'media' => 'media_abc123',
    'language' => 'en',
    'caption' => [
        'preset' => 'beast',
        'alignment' => 'bottom'
    ],
    'addStickers' => true,
    'musicId' => 'upbeat_001'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.slidevid.ai/v1/project/create/add-captions"

	payload := strings.NewReader("{\n  \"media\": \"media_abc123\",\n  \"language\": \"en\",\n  \"caption\": {\n    \"preset\": \"beast\",\n    \"alignment\": \"bottom\"\n  },\n  \"addStickers\": true,\n  \"musicId\": \"upbeat_001\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("x-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.slidevid.ai/v1/project/create/add-captions")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"media\": \"media_abc123\",\n  \"language\": \"en\",\n  \"caption\": {\n    \"preset\": \"beast\",\n    \"alignment\": \"bottom\"\n  },\n  \"addStickers\": true,\n  \"musicId\": \"upbeat_001\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.slidevid.ai/v1/project/create/add-captions")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"media\": \"media_abc123\",\n  \"language\": \"en\",\n  \"caption\": {\n    \"preset\": \"beast\",\n    \"alignment\": \"bottom\"\n  },\n  \"addStickers\": true,\n  \"musicId\": \"upbeat_001\"\n}"

response = http.request(request)
puts response.read_body

{
  "success": true,
  "data": {
    "videoId": "vid_caption_abc123xyz",
    "projectId": "proj_caption_abc123xyz",
    "status": "STARTED"
  }
}

{
  "success": false,
  "message": "media: Media ID is required"
}

{
  "success": false,
  "message": "media: Media not found"
}

{
  "success": false,
  "message": "musicId: Music \"invalid_music\" not found."
}

Try it out! Use the API playground on the right to test the Add Captions endpoint directly.

Overview

Add Captions automatically transcribes your video and adds professional-looking captions with customizable styles. Perfect for:

Social media content (TikTok, Instagram Reels, YouTube Shorts)
Accessibility compliance
Increasing video engagement
Multi-language content
Educational videos

Captions are automatically synced with your video’s audio and support multiple styling presets.

Endpoint

POST /v1/project/create/add-captions

Required Fields

string

required

Media ID of the video to add captions to (as a string)

Optional Fields

string

Custom name for the project (max 100 characters). If not provided, a name will be auto-generated.

string

Background music ID from /v1/music/list (max 30 characters)

object

Caption settings for the video

Show Caption Object

string

default:"classic"

Caption preset style. Available presets: default, beast, umi, tiktok, wrap1, wrap2, ariel, hooked, classic, active, bubble, glass, comic, glow, pastel, neon, retroTV, red, marker, modern, blue, vivid.

string

default:"bottom"

Caption position on the video: top, middle, or bottom

string

default:"en"

Language code for the video (2 characters). Example: en, es

string

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

object

Custom metadata object (max 5KB JSON)

Request Examples

Basic Caption Addition

const response = await fetch('https://api.tryslidevid.ai/v1/project/create/add-captions', {
  method: 'POST',
  headers: {
    'x-api-key': process.env.SLIDEVID_API_KEY,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    media: 'media_abc123'
  })
});

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

Advanced with Custom Styling

const addCaptionsAdvanced = async () => {
  const response = await fetch('https://api.tryslidevid.ai/v1/project/create/add-captions', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.SLIDEVID_API_KEY,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      name: 'Social Media Captioned Video',
      media: 'media_xyz789',
      language: 'en',
      caption: {
        preset: 'modern',
        alignment: 'bottom'
      },
      addStickers: false,
      musicId: 'upbeat_background_001',
      webhook: 'https://yoursite.com/webhook',
      metadata: {
        campaignId: 'social-media-2024',
        platform: 'tiktok'
      }
    })
  });

  return await response.json();
};

With Background Music

const addCaptionsWithMusic = async () => {
  const response = await fetch('https://api.tryslidevid.ai/v1/project/create/add-captions', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.SLIDEVID_API_KEY,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      name: 'Product Demo with Captions',
      media: 'media_product_demo',
      language: 'en',
      addStickers: false,
      caption: {
        preset: 'modern',
        alignment: 'bottom'
      },
      musicId: 'calm_background_music'
    })
  });

  return await response.json();
};

Response

{
  "success": true,
  "data": {
    "videoId": "vid_caption_abc123xyz",
    "projectId": "proj_caption_abc123xyz",
    "status": "STARTED"
  }
}

{
  "success": false,
  "message": "media: Media ID is required"
}

{
  "success": false,
  "message": "media: Media not found"
}

{
  "success": false,
  "message": "musicId: Music \"invalid_music\" not found."
}

Webhook Notification

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

Webhook Payload

{
  "status": "COMPLETED",
  "data": {
    "videoId": "vid_caption_abc123xyz",
    "status": "COMPLETED",
    "url": "https://cdn.tryslidevid.ai/videos/abc123xyz.mp4",
    "shareUrl": "https://cdn.tryslidevid.ai/shared/abc123xyz.mp4",
    "metadata": {
      "projectId": "proj_caption_abc123xyz"
    }
  },
  "message": "Video completed"
}

Caption Presets

Available caption presets for the caption.preset field:

Preset	Description
`default`	Default caption style with bold text and shadow effects
`beast`	Bold uppercase style with Komika font
`umi`	Yellow glowing text style
`tiktok`	Viral & trendy style, perfect for social media
`wrap1`	Wrapped style with red background highlight
`wrap2`	Wrapped style with blue background highlight (uppercase)
`ariel`	Bold uppercase style with purple highlight
`hooked`	Brand style with purple background
`classic`	Clean, simple captions with black background (Default)
`active`	Green background with bold text
`bubble`	White background bubble style
`glass`	Glassmorphic transparency effect
`comic`	Comic Sans font with colorful style
`glow`	Pink and orange glow effects
`pastel`	Soft pastel pink background
`neon`	Green neon glow effect
`retroTV`	Retro TV style with cyan glow
`red`	Red glow effect with white text
`marker`	Yellow marker/highlighter style
`modern`	Contemporary white background style
`blue`	Blue background style
`vivid`	Vibrant pink background with uppercase text

Best Practices

Clear Audio

Ensure your video has clear audio for accurate transcription

Language Match

Set the correct language code for best transcription accuracy

Style Selection

Choose caption styles that match your content and brand

Positioning

Bottom alignment works best for most social media content

Error Handling

Error	Description	Solution
`media: Media ID is required`	Missing media ID	Provide a valid media ID string
`media: Media not found`	Invalid media ID	Ensure the media ID exists and is correct
`media: Media is not a video`	Media is not a video type	Ensure the media ID points to a video, not an image
`language: Language code too long`	Invalid language code	Use 2-character language code (e.g., “en”, “es”)
`musicId: Music "X" not found`	Invalid music ID	Use valid music ID from `/v1/music/list`
`caption.alignment: Invalid enum value`	Invalid alignment	Use `bottom`, `middle`, or `top`
`webhook: Must be a valid HTTPS URL`	Invalid webhook URL	Ensure webhook URL uses HTTPS
`Not enough credits`	Insufficient credits	Top up your account credits

Next Steps

List Videos

View all your created videos

Video Details

Check your video processing status

Music Library

Browse available background music

Webhooks Guide

Learn how to handle webhook notifications

Authorizations

x-api-key

string

header

required

Body

application/json

media

object[]

required

Array containing exactly one video file

Required array length: 1 element

Show child attributes

language

string

default:en

required

Language code for transcription (exactly 2 characters)

Required string length: 2

caption

object

required

Caption styling and positioning settings

Show child attributes

addStickers

boolean

default:false

Add AI-generated stickers to enhance video engagement

musicId

string

Background music ID from /v1/music/list

Maximum string length: 30

webhook

string

HTTPS URL for status notifications (max 500 characters)

Maximum string length: 500

metadata

object

Custom metadata object (max 5KB)

Response

Add Captions created successfully

success

boolean

data

object

Show child attributes

List Music Extend Video

Getting Started

Resources

Videos

Templates

Overview

Endpoint

Required Fields

Optional Fields

Request Examples

Basic Caption Addition

Advanced with Custom Styling

With Background Music

Response

Webhook Notification

Caption Presets

Best Practices

Clear Audio

Language Match

Style Selection

Positioning

Error Handling

Next Steps

List Videos

Video Details

Music Library

Webhooks Guide

Authorizations

Body

Response

​Overview

​Endpoint

​Required Fields

​Optional Fields

​Request Examples

​Basic Caption Addition

​Advanced with Custom Styling

​With Background Music

​Response

​Webhook Notification

​Caption Presets

​Best Practices

Clear Audio

Language Match

Style Selection

Positioning

​Error Handling

​Next Steps

List Videos

Video Details

Music Library

Webhooks Guide

Authorizations

Body

Response

Overview

Endpoint

Required Fields

Optional Fields

Request Examples

Basic Caption Addition

Advanced with Custom Styling

With Background Music

Response

Webhook Notification

Caption Presets

Best Practices

Error Handling

Next Steps