Burn captions into a video

The caption.burn job burns subtitles permanently into a video. Provide an SRT, VTT, or ASS file as the subtitles input, or omit it to auto-transcribe the audio. Style the text with web-hex colors, an outline, a background box, and a position.

Accepts: video · Type: caption.burn

Request

import { createClient, outputUrl } from "@rendobar/sdk";

const client = createClient({ apiKey: "rb_YOUR_KEY" });

const job = await client.jobs.create({
  type: "caption.burn",
  inputs: {
    source: "https://cdn.rendobar.com/assets/examples/sample.mp4",
    subtitles: "https://cdn.rendobar.com/assets/examples/sample.srt",
  },
  params: { fontFamily: "Inter", fontSize: 48, boxEnabled: true },
});

const result = await client.jobs.wait(job.id);
console.log(outputUrl(result));

import requests
res = requests.post(
    "https://api.rendobar.com/jobs",
    headers={"Authorization": "Bearer rb_live_YOUR_KEY"},
    json={
        "type": "caption.burn",
        "inputs": {
            "source": "https://cdn.rendobar.com/assets/examples/sample.mp4",
            "subtitles": "https://cdn.rendobar.com/assets/examples/sample.srt",
        },
        "params": {"fontFamily": "Inter", "fontSize": 48, "boxEnabled": True},
    },
)

curl -X POST https://api.rendobar.com/jobs \
  -H "Authorization: Bearer rb_live_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "type": "caption.burn",
    "inputs": {
      "source": "https://cdn.rendobar.com/assets/examples/sample.mp4",
      "subtitles": "https://cdn.rendobar.com/assets/examples/sample.srt"
    },
    "params": { "fontFamily": "Inter", "fontSize": 48, "boxEnabled": true }
  }'

Omit subtitles to auto-transcribe. The spoken language is detected by default (language: "auto"). Pass an ISO-639-1 code to skip detection.

What inputs does it take?

string

required

URL of the source video to caption.

string

URL of an SRT, VTT, or ASS subtitle file. A provided ASS file is burned as-is, preserving its own styling. Omit to auto-transcribe the audio.

string

URL of your own font file (TTF, OTF, TTC, WOFF, WOFF2). Captions render in it, and it takes priority over fontFamily, so you do not need to know the family name inside your own file. An uploaded asset’s content URL works here.

Parameters

enum

default:"auto"

Spoken language for the auto-transcribe path, as an ISO-639-1 code (e.g. en, es, ja) or auto to detect. English uses a faster model. Everything else routes to multilingual transcription. Ignored when a subtitle file is provided.

string

default:"Inter"

Font family, or a CSS fallback stack. Any Google Fonts family works by name and is fetched at render time. Seven are bundled and resolve instantly: Inter, Roboto, Montserrat, Poppins, Oswald, Anton, Bebas Neue. A stack falls through in order, so "Lato, Inter, sans-serif" tries each in turn. To render in your own file, pass its URL as the font input, which wins over this parameter.

string

deprecated

Deprecated alias for font. Still accepted so existing clients keep working. font wins when both are present.

integer

default:"48"

Font size in output pixels. Range 8–400.

string

default:"#FFFFFF"

Text fill color as web hex (#RRGGBB or #AARRGGBB, alpha first).

boolean

default:"true"

Render the text bold.

boolean

default:"false"

Render the text italic.

string

default:"#000000"

Outline (stroke) color as web hex.

number

default:"2"

Outline thickness in pixels. Range 0–20.

number

default:"1"

Drop-shadow depth in pixels. Range 0–20. 0 disables the shadow.

boolean

default:"false"

Draw a filled background box behind the text (the accessibility “subtitle bar”).

string

default:"#000000"

Background box color as web hex. Applies when boxEnabled is true.

number

default:"0.6"

Background box opacity, 0 (transparent) to 1 (opaque).

enum

default:"bottom"

Vertical placement. One of bottom, center, top.

enum

default:"center"

Horizontal alignment. One of left, center, right.

integer

default:"60"

Vertical margin in pixels. Range 0–2000.

integer

default:"40"

Horizontal margin in pixels. Range 0–2000. Also bounds the line-wrap width.

integer

Maximum characters per line on the auto-transcribe path. Range 10–80.

Like every job, this returns the standard response. See Job output for the shape and how to read the result. For animated word-level captions instead, see captions.animate.

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Burn captions into a video

Request

What inputs does it take?

Parameters

See also

​Request

​What inputs does it take?

​Parameters

​See also

Request

What inputs does it take?

Parameters

See also