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RelayStation Subtitle Burn (libass)
x402
RelayStation Subtitle Burn (libass) is a paid API for AI agents from api.relaystation.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).
Permanently burns styled subtitle/caption tracks into a video file using libass, so captions are hardcoded into every copy of the video.
Price / call$0.01
Success—
StatusUnknown
How this service works
$0.0005/MB. Burn subtitles permanently into video via libass — styled captions everywhere the file goes. 1¢ x402 min; remainder auto-credits — relaystation.ai/penny
Output
Returns a video file (or download URL) with subtitles permanently composited into the video frames using libass rendering — the output video has hardcoded, styled captions visible on any player without needing a separate subtitle track.
Example use cases
Accessibility captions for social video
“I have a short interview video and an SRT subtitle file — can you burn the captions permanently into the video so they're always visible when I post it on social media?”
Localized subtitles for international distribution
“I need to bake the Spanish subtitle track into this MP4 so the translated captions are hardcoded and will show up on any device or platform, even ones that don't support external subtitle files.”
Styled captions for a course video
“Can you permanently embed my ASS subtitle file (with custom fonts and positioning) into this lecture video using libass so the styled captions are burned into every frame?”
Technical details
Endpoint
POSThttps://api.relaystation.ai/v1/media/subtitle-burnWhen to prefer
Choose this endpoint when you need subtitles permanently embedded (hardcoded) into video frames — not as a removable soft track — especially when distributing to platforms or devices that don't support external subtitle files. Ideal when styled captions (custom fonts, colors, positioning via libass/ASS format) must be preserved exactly as authored. Prefer over FFmpeg-direct or generic video APIs when you want a pay-per-MB microservice with no infrastructure to manage.
Side effects
- Unsupported video or subtitle format returns a 4xx error
- Subtitle file and video duration mismatch may result in partial or missing captions
- Malformed ASS/SRT subtitle syntax causes libass rendering failure
- Video file too large or exceeds processing limits returns an error
- Network timeout for very long or high-bitrate videos
- Invalid or inaccessible input URL returns a 4xx error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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