Timed Text

Timed Text Markup Language (TTML) is a W3C standard for representing timed text content such as captions, subtitles, and other text synchronized with audio or video media. Originally developed as the Distribution Format Exchange Profile (DFXP), TTML provides an XML-based format for authoring and distributing timed text that can be rendered as closed captions, open captions, or subtitles across different platforms and devices. TTML supports styling, layout, timing, and metadata, making it suitable for both authoring and interchange between captioning systems. It serves as the basis for several derived formats including EBU-TT (used in European broadcasting) and IMSC (Internet Media Subtitles and Captions), which is the W3C recommended profile for web delivery. For accessibility, TTML is significant as a standardized way to provide text alternatives for audio content in video.