SRT, ASS, VTT and PGS explained

Four subtitle formats, doing the same job in different ways. Which one you have decides how much control you get over the look.

SRT — text and timing

A text file of timings and lines, nothing more. AIX can apply its subtitle size, colour and outline controls to SRT text. AIX supports SRT text subtitles.

ASS — styled and positioned

Advanced SubStation Alpha carries its own fonts, colours, positions and even simple animation. Used heavily for anime and fan subtitles. Style override is on by default, so your own size, colour and outline settings replace the file’s; switch it off to see the subtitles as the author intended.

VTT and PGS

VTT is the web standard, close to SRT with light styling, and what you get from browser-based sources. PGS is different in kind — it is found inside disc rips and holds subtitles as images rather than text, so the typeface, size and colour are fixed, and the style controls do not apply to them.

Which format to choose when a site offers several

Take the SRT unless you have a reason not to. AIX’s styling controls can adjust SRT text; compatibility elsewhere depends on the receiving player. Choose ASS when the subtitles are doing something the plain format cannot — positioned signs, karaoke, styled captions in animation — and switch style override off so it looks as its author intended. Every format AIX Player opens is listed on the subtitles page.

Why image-based subtitles behave differently

PGS subtitles from disc rips are pictures of text rather than text itself. AIX’s text-style controls do not recolour or change the typeface of picture subtitles. VobSub from DVDs and DVB from TV recordings are picture-based too, and all three decode in AIX Player. They still show on the TV when you cast, but if you want control over how subtitles look, a text-based file for the same film gives you it.

Encoding, and why characters sometimes break

A subtitle file is plain text, and plain text has to be saved in a particular character encoding. Files made for one language and read as another turn accented and non-Latin characters into boxes or question marks. AIX Player reads subtitle files saved as UTF-8, or as UTF-16 with a byte-order mark. A file saved in an older regional encoding can show the wrong characters; saving it again as UTF-8 in a text editor, or downloading a UTF-8 copy, fixes it.

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