# How to Play ASS, SSA and PGS Subtitles on Mac | Stoic

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## Key takeaways

* ASS and SSA are text with styling instructions: fonts, colours, position, animation. PGS is a bitmap from a Blu-ray.
* QuickTime Player does not open MKV, where these subtitles usually live, so you need another player either way.
* ASS needs a renderer such as libass to look right. PGS only needs to be drawn, but cannot be restyled or searched.
* ffprobe tells you which format a track is in a few seconds.

Subtitle trouble on a Mac usually starts the same way. The film opens, the sound is fine, and the subtitles are missing, plain, or sitting in the wrong place. Before changing anything, it helps to know which of two very different things you are dealing with.

## ASS and SSA: text plus a style sheet

SSA (SubStation Alpha) and its successor ASS (Advanced SubStation Alpha) are text formats. Each line of dialogue is stored as words, and a style section says how to draw them: which font, what size and colour, where on the screen, whether they fade, move or rotate. Fansub groups use this heavily for on-screen signs, karaoke and typeset titles.

The catch is that the file is only a script. A player has to interpret it. Players with a proper ASS renderer (most use libass) draw the styles as written. Players without one fall back to plain text and throw the styling away, which is why a typeset sign turns into a line of white text at the bottom of the picture. Fonts matter too: ASS files often attach their own fonts inside the MKV, and a player that ignores them substitutes something else.

## PGS: a picture of the words

PGS (Presentation Graphic Stream) is the subtitle format on Blu-ray discs, and it survives in MKV rips as `hdmv_pgs_subtitle`. There are no words in it. Each subtitle is a small bitmap with timing and a position. VobSub, from DVDs, works the same way. For a player the job is simpler, just draw the picture at the right moment, so PGS support is common.

The trade is flexibility. You cannot change the font or size of a PGS subtitle because there is no font. You cannot search it, because there is nothing to search. If it is too small or too low, the only real fixes are scaling the whole picture or moving the position, or converting it to text by optical character recognition, which is a tool job and never perfect.

## See which one you have

List the subtitle tracks with ffprobe:

```
ffprobe -v error -select_streams s \
  -show_entries stream=index,codec_name:stream_tags=language,title \
  -of default=noprint_wrappers=1 file.mkv
```

We ran this on a test file and got `codec_name=ass` for a styled text track. You will see `hdmv_pgs_subtitle` for Blu-ray bitmaps, `dvd_subtitle` for DVD ones and `subrip` for plain SRT. Our [free browser tools](https://www.stoicplayer.com/tools) can also read the track list without a Terminal.

## Why QuickTime is not the answer

These subtitles almost always travel inside Matroska files, and QuickTime Player does not open MKV. If your goal is to play the original file with its subtitles intact, start with [how to play MKV on Mac without converting](https://www.stoicplayer.com/blog/how-to-play-mkv-on-mac). Remuxing to MP4 is possible, but MP4 cannot hold ASS styling or PGS the way MKV does, so converting is where subtitles get lost.

## What to look for in a player

* A real ASS renderer, not a text fallback. The test is a file with typeset signs: do they stay in place and keep their style?
* Support for fonts attached to the file, and for fonts you install yourself.
* PGS drawn at the right size and position on your display.
* A timing offset, for the day the subtitles run a second early.

## How Stoic handles each

Stoic renders ASS and SSA through libass, with the file's attached fonts first and system fonts after, and it does not override the author's styling, because overriding it would break the typesetting. PGS and VobSub are drawn as the bitmaps they are. That has one visible consequence we show rather than hide: the transcript search works on text tracks only, and when you pick a PGS track the panel tells you there is no text to search.

Subtitle files beside the film are picked up automatically, and the full list of supported subtitle formats is on the [formats page](https://www.stoicplayer.com/formats). If subtitles sit too close to the bottom edge, Settings has a distance-from-bottom control that also moves styled subtitles.

## Subtitles drawn the way they were made

Stoic plays ASS, SSA, PGS and more on Apple silicon Macs running macOS 26 or later. One purchase covers up to three Macs.

[Buy now](https://checkout.dodopayments.com/buy/pdt%5F0NoFF3ULkfeucBnMycGW2?quantity=1&redirect%5Furl=https%3A%2F%2Fwww.stoicplayer.com%2Factivate&paymentCurrency=USD&showCurrencySelector=true)

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> ASS and SSA are styled text, PGS is a picture. Why the difference decides what you can change, how to tell which you have, and which Mac players render them.

Source: https://www.stoicplayer.com/blog/ass-ssa-pgs-subtitles-on-mac