What is .SUP file format?
The .sup file extension stands for subtitle bitmap image extracted from a Blu-ray movie; it contains subtitle text graphics that are displayed during movie playback. The .sup subtitles are encoded with PGS codec, and sometimes known as PGS subtitles. It can be used for adding DVD subtitles to movies with authoring programs such as IfoEdit.
Which players support .sup subtitles?
Blu-ray Players and some HD Media Players (e.g. WD TV Live Hub, Netgear NeoTV 550 Ultimate HD Media Player)
How to convert .sup subtitles when ripping a Blu-ray Disc?
ByteCopy is a by far the exclusive Blu-ray ripper that converts .sup subtitles to .sub when ripping Blu-ray to MKV.