Caption conversion

Convert EBU-STL to SRT

EBU-STL (EBU Subtitling Data Exchange Format) to SubRip Subtitle (SRT). Convert in the web app, automate with the REST API, or run it offline with the CLI.

Convert EBU-STL to SRT free How to convert

Converting EBU-STL to SRT unlocks binary broadcast subtitles for web players, editors and translation tools. The text and timing come across cleanly. The main thing to watch is the timecode origin, because broadcast STL files are usually timed from a 10:00:00:00 programme start.

What carries over

Subtitle text, decoded from the STL character code table into Unicode
Line breaks and italics
Timing, converted from 25 fps frames to milliseconds (one frame is 40 ms)

What changes

GSI header metadata (titles, language, translator) is not stored, because SRT has no header
Teletext colors, double height and boxing are dropped
Vertical position and justification are lost
Timecodes stay relative to the programme start unless you apply an offset

How to convert EBU-STL to SRT

The same conversion engine powers all three, so a job you set up in the web app produces identical output from the API or CLI.

In the web app

Sign in to the web app, or start a free trial.
Upload your .stl file and select EBU STL as the source profile.
Select SubRip Video Subtitle Script as the target profile.
Review the recommended settings for this conversion.
Run the conversion and download your .srt file.

With the API

POST /jobs

curl -X POST https://api.closedcaptionconverter.com/jobs \
  -H "x-api-key: YOUR_API_KEY" \
  -F "source=@input.stl" \
  -F 'config={
    "job_type": "convert",
    "source_profile": "EBU STL",
    "target_profile": "SubRip Video Subtitle Script",
    "offset": "10:00:00:00",
    "offset_type": "subtract"
  }'

See API Getting Started for authentication and response handling.

With the CLI

Command line

ccconverter \
  --source input.stl \
  --target output.srt \
  --source_profile "EBU STL" \
  --target_profile "SubRip Video Subtitle Script" \
  --offset 10:00:00:00 \
  --offset_type subtract

The CLI runs fully offline on macOS, Windows and Linux. See the CLI docs for every flag.

Recommended settings

Timecode offset	Subtract the programme start (often `10:00:00:00`) so subtitles begin at zero for web video. Offset type auto can detect it.
Target encoding	UTF-8, so accented and non-Latin characters survive.

Format-specific options are covered in Encoding & Decoding Options and Profiles & Formats.

EBU-STL to SRT questions

Broadcast programmes typically start at timecode 10:00:00:00, and STL subtitles are timed to it. Apply a timecode offset (subtract 10:00:00:00, or use the auto offset type) to start at zero.

No. Make sure you choose the EBU STL source profile for binary EBU Tech 3264 files. Spruce STL is a different, text-based format with the same extension.

Not in SRT. If you need the programme metadata preserved, convert to EBU-TT instead.

Learn more about these formats

Source

EBU-STL (EBU Subtitling Data Exchange Format)

What an EBU-STL (.stl) subtitle file is, how the EBU Tech 3264 GSI header and TTI blocks work, frame rates and character tables, and how to convert STL files.

Target

SubRip Subtitle (SRT)

What an SRT (.srt) subtitle file is, its timing and numbering rules, supported tags and encoding, and how to convert SRT to SCC, WebVTT, EBU-STL and more.

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