SRT, ASS, VTT and PGS explained

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

SRT — plain and universal

A text file of timings and lines, nothing more. It carries no styling at all, which is exactly why it works everywhere and why your own size, colour and outline settings apply cleanly to it. The safest format to look for.

ASS — styled and positioned

Advanced SubStation Alpha carries its own fonts, colours, positions and even simple animation. Used heavily for anime and fan subtitles. It looks as the author intended, but if you would rather it matched your own settings, turn on style override.

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 is fixed and cannot be restyled, only resized and repositioned.

Which format to choose when a site offers several

Take the SRT unless you have a reason not to. It carries no styling of its own, which means your size, colour and outline settings apply cleanly, and it works everywhere. Choose ASS when the subtitles are doing something the plain format cannot — positioned signs, karaoke, styled captions in animation — and accept that it will look as its author intended rather than as you set it.

Why image-based subtitles behave differently

PGS subtitles from disc rips are pictures of text rather than text itself. Nothing can recolour or re-font them, because there is no font involved — only an image per line. They can still be resized and repositioned, and they cast to a television perfectly well, 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 the common encodings, so files that looked broken elsewhere usually display correctly — and where one is genuinely unusual, another file for the same film will load cleanly.

Worth knowing