Convert SUP to SRT online
Turn Blu-ray PGS subtitle files into text-based SRT in seconds. OCR runs entirely in your browser — your files never leave your device.
Drag & drop a .sup file, or browse
Processed locally in your browser — nothing is uploaded.
Features of the SUP to SRT converter
100% Private
Every step — PGS frame extraction, image thresholding, and OCR — runs in your browser. Your subtitle files never leave your device.
No signup, no limits
Free forever with no daily caps, no queues, no watermarks, and no account. Drop a file, pick a language, and download an SRT.
60+ languages
Powered by LSTM OCR training data — recognise English, Spanish, French, Chinese, Japanese, Arabic, and dozens more.
Highly accurate
Adaptive image processing and an LSTM OCR engine turn each Blu-ray subtitle frame into clean, well-timed subtitle cues.
How it works
- 1
Upload your .sup file
Drag and drop a Blu-ray PGS (.sup) subtitle file onto the converter. Files are read locally — nothing is uploaded.
- 2
Choose an OCR language
Pick the language spoken in the video. The OCR engine downloads the right trained data and recognises each subtitle frame.
- 3
Download your SRT
Frames are decoded, binarised, and recognised into text, then assembled into a standard SRT file ready to use.
Frequently asked questions
How accurate is the OCR?
Accuracy depends heavily on the source image quality and the selected language. Clear, high-contrast Blu-ray subtitles typically recognise very well. Italic or stylised fonts may reduce accuracy. The most common mistake that results in high inaccuracy is selecting the wrong OCR language. You may want to proofread the output SRT.
Are my subtitle files uploaded to a server?
No. The entire conversion — PGS frame extraction, image thresholding, and OCR — runs in your browser. Your files never leave your device. We have zero visibility of your source SUP files and output SRT files.
What is a SUP / PGS file?
SUP files contain Presentation Graphic Stream (PGS) subtitles used on Blu-ray discs. They store subtitle frames as bitmap images with unique RLE encoding, so a specialised extractor and an OCR engine are required to produce a text-based SRT file.
What can I do if the output has mistakes?
Double-check if the correct OCR language is selected — this is the most common fix. Stylised fonts can also increase the number of mistakes. You can also open the SRT in any text editor and correct timestamps or spelling manually.
What browsers are supported?
A modern browser is required — Chrome 111+, Edge 111+, Firefox 113+, or Safari 16.4+. The converter uses WebAssembly and SharedArrayBuffer for the OCR engine, so older browsers such as Internet Explorer, legacy Edge, or Safari 15 and below are not supported.
How do I get .sup files from my Blu-ray?
Use a tool like MKVToolNix, MakeMKV or eac3to to extract the PGS subtitle track from your Blu-ray disc. These tools can save the subtitle stream as a standalone .sup file that you can then convert here.
Which languages are supported?
Over 60 languages are supported through the OCR engine training data, including English, Spanish, French, German, Chinese, Japanese, Korean, Arabic, and more.
Why does the first conversion take longer to start?
The OCR engine downloads its WebAssembly binary and language training data on first use. These are cached by your browser, so subsequent conversions of the same language start much faster. Larger SUP files with many captions will also take longer to process.
What output format do I get?
You get a standard .srt (SubRip) file — the most widely supported subtitle format. It works with VLC, Plex, HandBrake, YouTube, and virtually every media player and video editor.
Need more subtitle tools?
This converter handles one file at a time. Need to convert several at once? subtitleone.cc supports batch processing of up to 10 subtitles simultaneously — plus source image preview and inspection, editing, resync, time shift, adjustment, cleaning and translation tools.