SubStation Alpha

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SubStation Alpha (or Sub Station Alpha), abbreviated SSA, is a subtitle file format that allows for more advanced subtitles than the conventional SRT and similar formats. To render these subtitles on Microsoft Windows, VSFilter is needed in conjunction with a DirectShow-aware video player.

It is also the name of the popular, now discontinued, tool used to edit the subtitles. See below for more on SSA / ASS subtitle editors.

This subtitle format is frequently used by anime fansubs by overlaying the subtitles onto video while being encoded or in a Matroska (MKV) container. This first operation is irreversible, and it's called hardsubbing. Hardsubs don't need VSFilter or other special resources. The latter describes softsubs, which are possible to modify or turn off altogether, and certain containers may accommodate several different subtitle streams.

Contents

[edit] Principal sections in a SSA subtitle

The most basic SSA subtitle is one like this (modified version from an original script):

[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/
; or email kotus@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

That means:

  • Script Info: general information about the script:
    • Title
    • Original Script
    • Script Updated By
    • Script Type (useful for compatibility)
    • Collisions (determines the stacking direction of the subtitles when two or more are present with no specific position: if Normal, subtitles are stacked from down to up; if Reverse, they're stacked from up to down, and can leave spaces under them)
    • PlayResX & PlayResY (useful for graphics and subtitle positioning. If only one present, the other is calculated with real video proportions)
    • PlayDepth (determines number of colors)
    • Timer (all timing is multiplied by this percentage, always written with decimal point and four decimal signs. If smaller than 100.0000, subtitles appear faster and sooner than programmed. If greater, lower and later)
  • V4 Styles: a "Format:" line, that specifies the meaning of the "Style:" line Fields, and one or plus "Style" lines, specifing the color, position, margins, the "shape" of a normal subtitle when adjusted to a determinated style (see "Events" section below). All boolean options are written as 0 or 1 (0=false, 1=true). Strange features are:
    • PrimaryColour. Subtitle filling color
    • SecondaryColour. If subtitle has karaoke commands, will appear in this color, changing to PrimaryColour.
    • TertiaryColour (OutlineColour in ASS). Border color
    • BackColour. Shadow color
    • MarginL, MarginR. Minimum margins from subtitles to video limits.
    • MarginV. Minimum margin from subtitles to a video limit, that changes with alignment: if top, distances are from video top; if bottom, distances are from video bottom; if centered, this is unused. In all margin parameters, line is normally cut in \n & \N commands and in spaces, when necessary. An optional parameter in Script Info (only available in ASS), WrapStyle, can change this.
    • Outline. Subtitle can be defined with a border, a rectangle or nothing.
    • Shadow. Distance from shadow to subtitle.
    • AlphaLevel. Transparency (0 is null, 255 is total)
    • Encoding. Useful for writing other alphabet characters in ASCII. With Latin characters, this is set to zero. With Japanese characters, it can be set to 128 (ex: ‹ó displays Sora kanji)
  • Events: the section with the subtitles. Timing and text are here, and it's also able to put special effects and style modifications, with commands with the same syntax: {\letters invoking command(parameters separated by comma)}, like in {\move(80,80,200,200,150,300)}. Strange parameters:
    • Marked. Unused.
    • Effect. There are three available effects for text appearing, all of them substitutable for commands and others.

If there is an only parameter, brackets are not used (ex. {\kf89}).

Two exceptions:

  • Inside braces can be more than one command. Ex. {\bord8\be1}
  • \N and \n commands don't use braces.

[edit] Advanced SubStation Alpha

Advanced SubStation Alpha (ASS) is a script that lets you create even 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.net
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

[edit] Editing programs

  • Aegisub - Despite the fact that it's a relatively new editor, it's the most advanced, and is focused mostly on typesetting. It works in Windows NT, 2000 and XP, and, with limited functionality, on Linux, FreeBSD and Mac OSX as well. Since it has the most extensive and comprehensive manual (which includes tutorials on working with the subtitle format), it also appeals to new users. The only dedicated general-purpose ASS/SSA editor that is still under active development. UTF-8 is properly supported, but beware that not all programs accepting ASS/SSA files can read UTF-8.
  • subtitleeditor - A tool to edit subtitles for GNU/Linux. (ASS,SSA,SubRip,MicroDVD,MPL2,MPsub,SubViewer 2.0)
  • Sabbu - An advanced SSA/ASS editor, focused mostly on timing. It runs in Windows and Linux. This program is a suitable replacement for the original Substation Alpha, as it is basically a more modern version of it. No longer developed.
  • Sub Station Alpha tool - Freeware, the original tool, which is very outdated and no longer developed, but still a favorite of some.
  • Subtitle Workshop - Freeware. It is not advised 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.
  • Subtitle Processor - Open Source hosted at SourceForge. It is feature rich general subtitle editor with good SSA/ASS support. Only major drawback is that it does not support Unicode.
  • Notepad, TextEdit, or other plain text editor - Despite not being the most efficient way to go about it, since ASS/SSA scripts are plain-text, they can be edited directly in any plain text editor.

[edit] External links

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