How to convert SUP (Blu-ray PGS) subtitles to SRT
Blu-ray subtitles are stored as PGS (Presentation Graphic Stream) — literally pictures of text saved in a .sup file. To edit, translate or use them on devices that only accept text subtitles, they must be OCR-converted to SRT. AI Subtitle Studio handles both steps with no external software: extract the track, then run the built-in OCR converter.
What is a SUP file?
A .sup file contains bitmap images of each subtitle line together with the timestamps for showing and hiding them (codec id: hdmv_pgs_subtitle). Because there is no text inside — only pixels — you cannot open a SUP in a text editor, load it into most translation tools, or restyle it. Many streaming boxes and TVs will not render SUP files at all.
Converting to SRT requires OCR (Optical Character Recognition): software reads each image and turns it back into text with the original timing.
How AI Subtitle Studio converts SUP to SRT
Extracting a PGS track (on the Extract screen) gives you the raw .sup file — extraction on its own does not produce text, so this is not the finished subtitle yet. Take that .sup to the Convert screen and click Convert: the app's own bundled OCR engine (on the graphics card through DirectML on Windows when available, on the CPU otherwise, including on Macs) reads the images and writes out a clean, fully timed .srt. No external OCR software is needed, and after a one-time download of the recognition model no internet connection is either. Common OCR mistakes — confused characters like l/I, stray SDH tags, broken line breaks — can be fixed afterwards with the built-in Clean Up tool's Fix OCR errors option, a local pattern-based pass that runs instantly offline (no AI model needed).
Convert SUP to SRT step by step
- Load the video or the .sup file Open Extract and drop your MKV/Blu-ray rip on the window. Embedded PGS tracks are listed with their language and format. If you already have a standalone .sup file, skip to the Convert step.
- Extract the PGS track Tick the PGS subtitle track and click Extract. This saves a .sup file, not yet an .srt.
- Convert it to SRT on the Convert screen Click Convert next to the finished track (or open Convert and add the .sup file), then click Convert. The built-in OCR engine processes the images into text with the original timestamps, producing an editable .srt file.
- Clean up and save Optionally open it in Tools → Clean Up with Fix OCR errors on to correct misreads, then save — your Blu-ray subtitles are now universal SRT text.
Convert your Blu-ray subtitles to SRT
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