Subtitle file formats

Timed text that a player shows over a video: dialogue, translations and captions for people who cannot hear the sound. Most subtitle files are plain text, a list of cues each with a start time, an end time and the words to show. Disc formats store the subtitles as images instead.

Formats

.ASS

Advanced SubStation Alpha subtitles

Styled subtitles in INI-like sections: styles, then timed dialogue lines.

.IDX

VobSub subtitles

Ripped DVD subtitles: a text index pointing into a .sub file of images.

.SBV

YouTube SubViewer captions

YouTube’s plain text captions: a time range line, then the text.

.SRT

SubRip subtitles

Plain text subtitles: numbered cues, each with a time range and its text.

.SUB

MicroDVD subtitles

Text subtitles timed in frames: start frame, end frame and text on one line.

.SUP

Blu-ray PGS subtitles

Blu-ray subtitles as images: PG segments with palettes and bitmaps.

.TTML

Timed Text Markup Language

The W3C’s XML subtitle format, used by broadcasters and streaming services.

.VTT

WebVTT subtitles

The subtitle format of the web: UTF-8 cues with positioning and styling.