SubStation Alpha (or Sub Station Alpha), abbreviated SSA, is a subtitle

file format A file format is a Computer standard, standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary format, pr ...

created by CS Low (also known as Kotus) that allows for more advanced subtitles than the conventional

SRT SRT may refer to: Automotive * SRT, (Speed & Racing Technology) American high-performance automobile group associated with Dodge, Chrysler and Jeep. * Suter Racing Technology, a Swiss Moto2 constructor * Selleslagh Racing Team, Belgium * Swiss ...

and similar formats. It is also the name of the popular, now discontinued tool used to edit subtitles. This subtitle format is frequently used in anime

fansub A fansub (short for fan-subtitled) is a version of a foreign film or foreign television program, typically anime or dorama which has been translated by fans (as opposed to an officially licensed translation done by paid professionals) and subtitl ...

s, either to overlay subtitles onto video while it is being encoded ( hardsubbing), or to store subtitle data alongside video data, often in a

Matroska Matroska is a project to create a container format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file. The Matroska Multimedia Container is similar in concept to other containers like AVI, MP4, or Advan ...

(MKV) container (softsubbing). It's not commonly used professionally except by Crunchyroll. The current version of SSA is v4.00. There are many freeware and open source subtitling applications that support the SSA format.

Principal sections in an SSA subtitle

A basic SSA subtitle:

 cript Info; This is a Sub Station Alpha v4 script.
; For Sub Station Alpha info and downloads,
; go to http://www.eswat.demon.co.uk/
Title: Neon Genesis Evangelion - Episode 26 (neutral Spanish)
Original Script: RoRo
Script Updated By: version 2.8.01
ScriptType: v4.00
Collisions: Normal
PlayResY: 600
PlayDepth: 0
Timer: 100,0000
 
 4 StylesFormat: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
Style: DefaultVCD, Arial,28,11861244,11861244,11861244,-2147483640,-1,0,1,1,2,2,30,30,30,0,0
 
vents 
Vent or vents may refer to:

 Science and technology Biology
*Vent, the  cloaca region of an animal
* Vent DNA polymerase, a thermostable DNA polymerase
 Geology
* Hydrothermal vent, a fissure in a planet's surface from which geothermally heated wa ...
Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: Marked=0,0:00:01.18,0:00:06.85,DefaultVCD, NTP,0000,0000,0000,,Like an angel with pity on nobody

Advanced SubStation Alpha

Advanced SubStation Alpha (ASS) is a script for more advanced subtitles than SSA. It is technically SSA v4+. It is able to produce anything from simple texts to manual graphic editing used in karaoke. There are few programs designed to create these scripts. The main feature of ASS is it has more specifications than normal SSA, like in styles programming. For example, the above script changed into ASS:

 cript Info; Script generated by Aegisub
; http://www.aegisub.org
Title: Neon Genesis Evangelion - Episode 26 (neutral Spanish)
Original Script: RoRo
Script Updated By: version 2.8.01
ScriptType: v4.00+
Collisions: Normal
PlayResY: 600
PlayDepth: 0
Timer: 100,0000
Video Aspect Ratio: 0
Video Zoom: 6
Video Position: 0
 
4+ Styles 



4 (four) is a  number,  numeral and digit. It is the  natural number following  3 and preceding  5. It is the smallest  semiprime and  composite number, and is  considered unlucky in many East Asian cultures.
 In mathematics 
Four is the smalles ...
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: DefaultVCD, Arial,28,&H00B4FCFC,&H00B4FCFC,&H00000008,&H80000008,-1,0,0,0,100,100,0.00,0.00,1,1.00,2.00,2,30,30,30,0
 
vents 
Vent or vents may refer to:

 Science and technology Biology
*Vent, the  cloaca region of an animal
* Vent DNA polymerase, a thermostable DNA polymerase
 Geology
* Hydrothermal vent, a fissure in a planet's surface from which geothermally heated wa ...
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:01.18,0:00:06.85,DefaultVCD, NTP,0000,0000,0000,,Like an Angel with pity on nobody\NThe second line in subtitle

Software support

Authoring software

Subtitle encoding software

Software tools to encode subtitle files into video containers (mkv, mp4, mov, ...):

Players and renderers

References

{{DEFAULTSORT:Substation Alpha Subtitle file formats