.ASS

Introduction

SubStation Alpha (.ssa) was a Windows subtitle editor of the 1990s, and its file format added styles, fonts, colours and positioning to subtitles. Advanced SubStation Alpha (.ass), version 4+ of the format, extended it further and is now the more common of the two.

ASS can do far more than plain subtitles: karaoke timing, rotation, movement, drawing and animated effects. It is widely used for fan-subtitled anime, and Matroska files often carry ASS tracks together with the fonts they need.

Structure

The file is text, divided into sections like an INI file. [Script Info] holds settings such as ScriptType: v4.00+ and the resolution the script was written for. [V4+ Styles] ([V4 Styles] in SSA) defines named styles. [Events] holds the subtitles themselves.

The styles and events sections each start with a Format: line naming the fields, then one line per item in that order. Each subtitle is a Dialogue: line with a layer, start and end times as h:mm:ss.cc (hundredths of a second), the style, and finally the text. Override tags in braces, such as {\i1} for italics or {\pos(x,y)} for a position, change the look of the text.

[Script Info]
ScriptType: v4.00+
PlayResX: 1920
PlayResY: 1080

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, Bold, Italic, Alignment, MarginV
Style: Default,Arial,64,&H00FFFFFF,0,0,2,40

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:01.00,0:00:03.50,Default,,0,0,0,,Where are we going?
Dialogue: 0,0:00:04.00,0:00:06.25,Default,,0,0,0,,{\i1}Somewhere we have never been.{\i0}

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