Advanced Substation Alpha (ASS) is a subtitle format designed to replace the standard Substation Alpha format. It supports font and color choosing for subtitles, as well as advanced effects such as positioning, moving, 3D rotation, karaoke, and many others. As such, it is used for typesetting.
Softsubbed or hardsubbed
ASS is often hardsubbed onto the video due to its complexity and lack of good compatibility. However, as there are a number of reasons to use softsubs, it has been gaining popularity in softsubbed form too. Since MKV is the only container that supports embedded fonts, it is usually the one in which you will see softsubbed ASS. Regardless, ASS karaoke is still almost always hardsubbed.
Softsubbed ASS issues
As it is not trivial to parse and render this subtitle format, its support is, unfortunately, rather limited. Many players (such as VideoLan Client) will strip down the tags and render all the subs on top of each other, making portions of the video unwatchable. It is recommended that you don't try to use ASS format without proper support - in this case, if an alternate SRT track is provided, then consider using it instead.
Under Windows, the user has a choice of either installing a DirectShow compatible filter, or using a player that naively supports it. An installed filter is sufficient for normal playback under any DirectShow-aware player.
- VSFilter: Previously known as DirectVobSub or TextSub. This is included in the CCCP
You can play ASS softsubbed mkv (probably others as well) with MPlayer. You will need to specify the subtitle ID, though. It's usually 0, so just add the -sid 0 argument to MPlayer, so, it's
mplayer -sid 0 <filename>
You can see what subtitle alternatives there are by running mplayer -identify <filename>.
Same as Linux.
- Aegisub: THE replacement for Medusa, still under development.
- Medusa Subtitling Station: A discontinued program designed for typesetting and karaoke-making.
- Sabbu: A replacement for Medusa, under development.
- Substation Alpha: The program that gave birth to the format.