Add Subtitles to Video via API

Burn subtitle files directly into your video for guaranteed display on any player. Supports SRT, ASS, and VTT formats with customizable font, size, and positioning.

Try it in your browser

Loading FFmpeg engine... (~31 MB)

Use the API

curl -X POST https://renderio.dev/v1/commands \
  -H "X-API-KEY: ffsk_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
  "ffmpeg_command": "-i {in_video} -vf subtitles={in_video} {out_video}",
  "input_files": {
    "in_video": "https://example.com/input.mp4"
  },
  "output_files": {
    "out_video": "output.mp4"
  }
}'

Need an API key? Get your free API key to start processing files programmatically.

Common Variations

Custom font and size

-i input.mp4 -vf "subtitles=subs.srt:force_style='FontSize=28,FontName=Arial'" output.mp4

ASS subtitle file

-i input.mp4 -vf ass=subs.ass output.mp4

Soft subtitles (selectable)

-i input.mp4 -i subs.srt -c copy -c:s mov_text output.mp4

With background box

-i input.mp4 -vf "subtitles=subs.srt:force_style='FontSize=24,BorderStyle=4,BackColour=&H80000000'" output.mp4

Related Operations

Add Watermark to Video via API | RenderIO Overlay Video via API | RenderIO Resize Video via API | RenderIO Convert MKV to MP4 via API | RenderIO

Need to process at scale?

Automate this with the RenderIO FFmpeg API. Process thousands of files programmatically or through no-code video automation.

Get your API key