SubStation Alpha

SubStation Alpha

Screenshot of SubStation Alpha Tool for edit subtitles
Filename extension	.ssa, .ass
Developed by	Kotus
Initial release	Before 23 November 1996 (1996-11-23)
Type of format	Timed text
Open format?	Yes

SubStation Alpha (or Sub Station Alpha), abbreviated SSA, is a subtitle file format created by CS Low (also known as Kotus) that allows for more advanced subtitles than the conventional SRT 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 fansubs, either to overlay subtitles onto video while it is being encoded (hardsubbing), or to store subtitle data alongside video data, often in a Matroska (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:

[Script 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
 
[V4 Styles]
Format: 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
 
[Events]
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,,{\pos(400,570)}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:

[Script 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
 
[V4+ Styles]
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
 
[Events]
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,,{\pos(400,570)}Like an Angel with pity on nobody\NThe second line in subtitle

Software support

Authoring software

Title	Platform	License	Notes
Aegisub	Windows, Linux, FreeBSD, Mac OS X	Free and open-source	Focused mostly on typesetting.
Gaupol	Linux and Windows	Free and open-source	Has partial support for Sub Station Alpha and Advanced Sub Station Alpha subtitles.
Gnome Subtitles	Linux	Free and open-source	Built-in video preview, times synchronization/shifting, translation, spellcheck, subtitle merge/split.
Jubler	Java	Free and open-source	Splitting, joining, time shifting, translation mode, styles (in SubStation or SRT formats)
Kainote	Windows	Free and open-source	Translation mode, subtitle comparison, audio spectrum / waveform with karaoke autosplitting tool
Sabbu	Windows, Mac OS X, Linux and BSD	Free and open-source	Focused mostly on timing. Abandoned since 2013.
Sub Station Alpha	Windows	Freeware	Outdated and no longer developed.
Subtitle Composer	Linux	Free and open-source	Supports SSA/ASSA formats, text style and colors, unsupported SSA styles are ignored.
Subtitle Edit	Linux and Windows	Free and open-source	Supports 250+ subtitle formats, translation, audio waveform preview
Subtitle Processor	Windows	Free and open-source	Unicode is supported from version 7.7, UTF-8 is preferred, other encodings are internally converted to UTF-8.
Subtitle Workshop	Windows	Freeware	Apparently abandoned. Not recommended because it is not a fully dedicated SSA/ASS editor, because it doesn't follow the strict rules about SSA subtitles, and it erases any style put in with another program.
VisualSubSync-Enhanced	Windows	Free and open-source	Forked from VisualSubSync, which was abandoned in 2013.
Subtitled Pro	Android	Non-free	A mobile subtitle editor app that supports importing, exporting, converting, editing, and hardsubbing of SSA/ASS files and other formats.

Subtitle encoding software

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

Title	Platform	License	Notes
FFmpeg	Windows, Linux, Mac OS	Free and open-source	FFmpeg can also encode and convert subtitles in video containers including 'Subtitles Character Encoding Conversion' for plaintext files and special characters
iSubtitle	MacOS	Freeware	Encoding of soft subtitled movies for Apple gears
HandBrake	Windows, Linux, Mac OS	Free and open-source	HandBrake is an open-source, GPL-licensed, multiplatform video transcoder
MKVToolNix	Windows, Linux, Mac OS, BSD, OpenIndiana	Free and open-source	MKVToolNix is a collection of tools for the Matroska media container format. See also MKVMerge, a part of MKVToolNix, which is often used to attach/merge subtitle and/or audio files to a video file.
XMedia Recode	Windows	Freeware	XMedia Recode is a free All-In-One video converter and audio converter tool
Subler	Mac OS	Free and open-source	Subler is an open-source GPL-licensed for the MP4 media container format. It is used to attach/merge subtitle and/or audio files to a video file.

Players and renderers

Title	Description
Avidemux	Open-source video editing and processing software product
DirectVobSub	a DirectShow codec for displaying SSA subtitles in Windows Media Player or other Directshow player (there is also a fork of it called xy-VSFilter).
DivX	The proprietary DivX Plus software supports this subtitle format
GStreamer	Open-source multimedia framework that supports SSA subtitles through its plugin architecture
HandBrake	Open-source video transcoder (video converter) that can process SSA subtitles (either soft-subbing or hard-subbing them, depending on the user's preference)
KooRaRoo Media	A media server and organizer for Windows. Supports rendering external subtitles as SSA on devices that don't support external or embedded subtitles.
libass	Open-source library used by Aegisub, Avidemux, GStreamer, HandBrake, MPlayer, Totem, VLC media player, XBMC, and many other open-source programs to render/process SSA subtitles
Media Player Classic Home Cinema	Open-source self-contained media player for Windows
MPlayer	Open-source media player that runs on Windows, Mac OS X, Linux, *BSD, Solaris, BeOS, Syllable, AmigaOS and MorphOS
mpv	Open-source media player that runs on Windows, Mac OS X, Linux, and *BSD; originally forked from MPlayer.
PS3 Media Server	Media server that works with PlayStation 3 systems (has some bugs with some effects)
Totem	GNOME's default media player that can render SSA subtitles via GStreamer
Universal Media Server	Media server that works with DLNA, UPnP and HTTP/S-capable devices
VideoPad	Video editing program from NCH Software that support .ssa subtitles
VirtualDub with the subtitler or textsub filters	Open-source video capture/processing utility for 32-bit and 64-bit Windows platforms
VLC media player	Open-source media player for Windows, Mac OS X, Linux, FreeBSD, OpenBSD, Solaris, BeOS and Syllable
PotPlayer	Media player for Windows, with a huge number of features and customizations, allowing screen recording, podcasts, and many user friendly shortcuts including global hotkeys
Kodi (formerly XBMC)	Open-source cross-platform Media Center program
xy-VSFilter	a DirectShow codec for displaying SSA subtitles in Windows Media Player or other Directshow player, included in the Combined Community Codec Pack and the K-Lite Codec Pack (it is a fork of DirectVobSub)

Further reading

• "SSA/ASS Subtitles". Matroska.org. CoreCodec, Inc. https://www.matroska.org/technical/subtitles.html#ssaass-subtitles. Retrieved 8 October 2020. 
• Kotus (18 February 2002). "Sub Station Alpha v4.00+ Script Format" (Microsoft Word Document). http://www.perlfu.co.uk/projects/asa/ass-specs.doc. Retrieved 11 July 2010. 
  • moodub.free.fr Mirror
• "ASS Tags". Aegisub Manual. aegisub.org. http://docs.aegisub.org/3.1/ASS_Tags/. Retrieved 25 March 2014.