SBV is understood mainly by YouTube and a few caption tools. SCC is what broadcasters, DVD authoring tools and video editors accept as closed captions. SBV is at home in uploading and downloading YouTube captions; SCC is the usual choice for closed captions for US and Canadian broadcast, DVD and some streaming deliveries.
The text is read as UTF-8 or UTF-16, whichever the file is. An older file in another code page is read using the charset it declares, or as Windows-1252 if it declares none, so accented letters in an unlabelled legacy file can come out wrong. A file that is not text, such as the picture-based subtitles of a DVD, is refused instead of being converted to nonsense. Of the styling, only italic, bold, underline and the position on screen (top, middle or bottom, left, centre or right) travel between formats; fonts, colours, outlines and effects do not. Captions are written as CEA-608 pop-on captions on channel CC1 at 29.97 fps drop-frame: lines are wrapped to 32 characters and at most four rows, characters the standard has no code for become the nearest plain letter or a question mark, and colours are not kept. A caption needs a moment to load, so cues closer together than that are painted on as they are typed or appear a few frames late. Input denser than the channel can carry (a byte pair a frame) loses the captions that could not start within two seconds of their time, and a cue that starts while another is showing cuts that one short.