Caption conversion

Convert PAC to EBU-STL

Screen Systems PAC (Poliscript) to EBU-STL (EBU Subtitling Data Exchange Format). Convert in the web app, automate with the REST API, or run it offline with the CLI.

Convert PAC to EBU-STL free How to convert

Converting PAC to EBU-STL moves subtitles from Screen Systems’ native binary format into the EBU Tech 3264 exchange format that most European broadcasters and playout systems ingest. Both formats are binary and frame-based, so timing transfers cleanly. Most of the work is in character sets and header metadata.

What carries over

Subtitle text and line breaks
Frame-accurate timing (25 fps PAC to STL25.01)
Vertical position and alignment, mapped to STL rows and justification
Italics where the target display standard supports them

What changes

The PAC code page is mapped to an STL character code table, for example PAC Arabic to STL Latin/Arabic
PAC files carry little programme metadata, so the STL GSI header fields come from the encoding options
Text in scripts that STL tables do not cover cannot be stored

How to convert PAC to EBU-STL

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 .pac file and select ScreenSystems Poliscript as the source profile.
Select EBU STL as the target profile.
Review the recommended settings for this conversion.
Run the conversion and download your .stl file.

With the API

POST /jobs

curl -X POST https://api.closedcaptionconverter.com/jobs \
  -H "x-api-key: YOUR_API_KEY" \
  -F "source=@input.pac" \
  -F 'config={
    "job_type": "convert",
    "source_profile": "ScreenSystems Poliscript",
    "target_profile": "EBU STL",
    "default_frameRate": 25,
    "encoding_options": [
      {
        "name": "Language Code",
        "selected": "Arabic"
      }
    ]
  }'

See API Getting Started for authentication and response handling.

With the CLI

Command line

ccconverter \
  --source input.pac \
  --target output.stl \
  --source_profile "ScreenSystems Poliscript" \
  --target_profile "EBU STL" \
  --source_frameRate 25 \
  --target_frameRate 25

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

Recommended settings

PAC Code Page	Leave on auto, or set it to the file’s language if characters decode incorrectly.
EBU-STL GSI options	Language Code, Country of Origin, Programme Title and display standard.
Frame rate	25 fps unless the source was authored at 30.

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

PAC to EBU-STL questions

Set the PAC Code Page decoding option to Arabic instead of auto. PAC files do not always identify their code page reliably.

Yes, when the PAC code page is decoded correctly and the STL uses the Latin/Arabic or Latin/Hebrew character table.

Yes. Any readable format can be converted to any writable format. Choose SRT as the target to get a plain-text file in UTF-8.

Learn more about these formats

Source

Screen Systems PAC (Poliscript)

What a PAC (.pac) subtitle file is, how the Screen Systems binary format stores text, timecode and code pages, and how to convert PAC to EBU-STL, SRT and more.

Target

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.

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