.SSA File Format

Introduction

SubStation Alpha was a Windows subtitle editor of the 1990s by Kotus, and version 4.00 of its script format is what most .ssa files use. Styles add fonts, colours and positioning to plain subtitles. Its successor, Advanced SubStation Alpha, replaced the style layout and added much more.

Modern renderers such as VSFilter and libass still read these files, and apply most of the newer tags to them.

Structure

The file is text in INI-like sections, with ScriptType: v4.00 in its [Script Info] section. The full reference is in the pages below.

• Script info – the header and its keys
• Styles – the named styles of [V4 Styles] and their 18 fields
• Events – dialogue, comments and effects in [Events]
• Override codes – codes inside subtitle text
• Fonts and graphics – embedded files and how they are encoded

[Script Info]
ScriptType: v4.00
Collisions: Normal

[V4 Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
Style: Default,Arial,28,65535,65535,65535,-2147483640,-1,0,1,3,0,2,30,30,30,0,0

[Events]
Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: Marked=0,0:00:01.00,0:00:03.50,Default,,0000,0000,0000,,Where are we going?

Variants

• SubStation Alpha v4.00 – the older .ssa scripts, with [V4 Styles] and legacy alignment codes
• Advanced SubStation Alpha v4.00+ – .ass scripts, with layers, alpha and numeric-keypad alignment

Links