TTMLDFXP

TTML DFXP, short for Timed Text Markup Language Distribution Format Exchange Profile, is a profile of TTML that defines a constrained subset of the language for the exchange of timed text data, such as subtitles and captions. It was developed under the auspices of the W3C to promote interoperability between authoring tools, encoders, and playback systems across broadcast and streaming environments.

A DFXP document typically includes a TTML root element, a head with style and region declarations, and a body containing a sequence of cues with begin and end times. The profile standardizes a set of semantics to describe layout, timing, and basic text formatting. It relies on CSS-like styling via style elements and region settings to control placement, size, and appearance, while limiting the use of more advanced TTML features to ensure compatibility across platforms.

Impact and usage: TTML DFXP served as a practical interoperability format in digital subtitle workflows and has influenced subsequent TTML profiles. It is commonly used in streaming manifests and broadcast subtitling contexts, sometimes in conjunction with MP4 or MPEG-DASH containers carrying TTML tracks.

Relationship: It is one of several TTML profiles that address different distribution scenarios. See also TTML, TTML2, DFXP.