How do I burn subtitles into a video through an API?

To burn subtitles into a video through an API, you usually use a video processing service that supports subtitle embedding / hardcoding. The exact steps depend on the API provider, but the workflow is generally the same:

Typical workflow

1. Upload the video to the API or provide a video URL.
2. Upload the subtitle file (usually .srt, .vtt, or .ass) or provide subtitle text/URL.
3. Create a processing job that tells the service to:
   • overlay the subtitles on the video
   • optionally choose font, size, color, position
4. Poll job status or use a webhook callback.
5. Download the processed video once complete.

Common API approaches

1) FFmpeg-based API

Some services expose a job that is effectively equivalent to:

ffmpeg -i input.mp4 -vf "subtitles=subtitles.srt" -c:a copy output.mp4

That is what “burning in” means: the subtitles are rendered into the pixels of the video.

2) Cloud video processing APIs

Examples:

• AWS MediaConvert
• Mux
• Cloudinary
• Shotstack
• Dalet / Brightcove / Wowza-type systems

They usually accept a JSON payload like:

• input video URL
• subtitle asset URL or file
• output settings
• burn/hardcode flag

Example API pattern

A generic request might look like:

{
  "input_video_url": "https://example.com/video.mp4",
  "subtitle_url": "https://example.com/subtitles.srt",
  "burn_subtitles": true,
  "output_format": "mp4"
}

And the response might return a job ID:

{
  "job_id": "abc123",
  "status": "queued"
}

Then you check:

GET /jobs/abc123

Until it returns:

{
  "status": "completed",
  "output_url": "https://example.com/output.mp4"
}

Important notes

• Burned-in subtitles cannot be turned off later.
• If you want subtitles to remain optional, use soft subtitles instead of burning them in.
• For SRT/VTT subtitles, make sure the character encoding is UTF-8.
• If your subtitles need styling, ASS/SSA is often better than SRT.

If you’re using your own API

If you control the backend, you can:

• receive video + subtitle file uploads
• run FFmpeg on a server/container
• return the processed file

Example FFmpeg command:

ffmpeg -i input.mp4 -vf "subtitles=subtitles.srt" -c:a copy output.mp4

Or with ASS styling:

ffmpeg -i input.mp4 -vf "ass=subtitles.ass" -c:a copy output.mp4

If you want, I can help with:

• a specific API provider (AWS, Cloudinary, Mux, Shotstack, etc.)
• a Node.js/Python example
• a design for your own video-processing API