---
title: Caption Burn-In
url: https://docs.kaltura.com/docs/rich-media-cms-apis/content-management/video-editing-caption-burn-in
---

## Caption Burn-In


Render caption text permanently into the video frame. Useful for social media distribution where players may not support subtitle tracks.

### KalturaRenderCaptionAttributes

| Parameter | Type | Description |
|-----------|------|-------------|
| `objectType` | string | `KalturaRenderCaptionAttributes` |
| `captionAssetId` | string | ID of the captionAsset to burn in (required) |
| `fontSize` | int | Font size in pixels |
| `fontColor` | string | Text color in ASS format: `&HBBGGRR&` |
| `fontName` | string | Font family name |
| `positionX` | int | Horizontal position (pixels from left) |
| `positionY` | int | Vertical position (pixels from top) |
| `borderStyle` | int | 1=OUTLINE, 3=OPAQUE_BOX |
| `borderColor` | string | Border/box color in ASS format |
| `bold` | int | Bold weight (0=normal, 1=bold) |
| `italic` | int | Italic (0=normal, 1=italic) |

### ASS Color Format

Colors use `&HBBGGRR&` (hex, blue-green-red reversed from RGB):

| Color | ASS Value |
|-------|-----------|
| White | `&H00FFFFFF&` |
| Black | `&H00000000&` |
| Yellow | `&H0000FFFF&` |
| Red | `&H000000FF&` |

### Burn-In Example


```bash
curl -X POST "$KALTURA_SERVICE_URL/service/media/action/addContent" \
  -d "ks=$KALTURA_KS" \
  -d "format=1" \
  -d "entryId=$KALTURA_ENTRY_ID" \
  -d "resource[objectType]=KalturaOperationResource" \
  -d "resource[resource][objectType]=KalturaEntryResource" \
  -d "resource[resource][entryId]=$KALTURA_SOURCE_ENTRY_ID" \
  -d "resource[resource][flavorParamsId]=0" \
  -d "resource[operationAttributes][0][objectType]=KalturaClipAttributes" \
  -d "resource[operationAttributes][0][offset]=0" \
  -d "resource[operationAttributes][0][duration]=60000" \
  -d "resource[operationAttributes][0][captionAttributes][objectType]=KalturaRenderCaptionAttributes" \
  -d "resource[operationAttributes][0][captionAttributes][captionAssetId]=$KALTURA_CAPTION_ASSET_ID" \
  -d "resource[operationAttributes][0][captionAttributes][fontSize]=24" \
  -d "resource[operationAttributes][0][captionAttributes][fontColor]=&H00FFFFFF&" \
  -d "resource[operationAttributes][0][captionAttributes][borderStyle]=1" \
  -d "resource[operationAttributes][0][captionAttributes][borderColor]=&H00000000&"
```