Sup files are subtitle files that contain pictures of text.
These types are subtitles are commonly called subpictures.
Subpictures are great for televisions, they can simply displays the pictures without having to worry about text encoding or exotic languages.
The downside of subpictures is that the text is hard to change, and that most computers can't properly display them.
This converter reads the text from the pictures, and turns them into a normal srt file. Three types of sup formats are supported: bluray, hddvd and normal dvd.
If you have a lot of sup files and you want to convert them all at once, you can take a look at the sup batch tool.
Optical character recognition (OCR) is used to convert the sup file to srt. Sup files always contain one stream of subtitles, but it does not contain any information about what language the subtitles are. Because of this, you have to manually select the language after you upload your file. A language is required to achieve the best OCR result.