Is TTML the same as DFXP?

DFXP was an earlier name for a distribution profile of TTML, and the term still appears in older specifications and tools. Treat them as the same family and confirm the exact profile.

Can TTML be converted to SRT?

Yes, with loss. Positioning, styling and region information have no equivalent in SRT, so what survives is the text and the timings.

Why was my valid TTML file rejected?

Almost always a profile mismatch: the file uses a feature the recipient profile forbids, or omits one it requires.

Does TTML support multiple languages in one file?

The format allows language attributes on content, but most distribution profiles expect one language per file. Follow the profile rather than the format’s capability.

Definition

What Is TTML?

VideoText editorial team. Updated September 13, 2026.

Direct definition

TTML (Timed Text Markup Language) is a W3C XML format for timed text. Streaming and broadcast pipelines often use a constrained profile such as IMSC rather than unrestricted TTML.

The sections below explain how TTML is used in transcription and subtitle work, what people often mix up, and which VideoText workflow applies when the next step is a file or review pass.

Key takeaways

TTML is XML, not a numbered plain-text cue list.
Ask which profile (IMSC, EBU-TT) a platform requires.
VideoText’s browser tool can convert TTML to SRT; that is conversion, not a claim that VideoText authors native IMSC packages.

Why profiles exist

Full TTML is large. Netflix, IMSC, and EBU profiles limit features so players can interoperate. Delivering “a TTML file” without the profile name is incomplete.

An XML format built for broadcast interchange

Timed Text Markup Language describes captions in XML, with separate regions for layout, styles for presentation, and timed content that references them. This separation is what lets TTML express positioning and styling far more precisely than a line-based format.

It is a standard rather than a single file shape, which is why files that are all validly TTML can still be unusable by a given system.

Why profiles matter more than the format name

Distributors define profiles — constrained subsets with required and forbidden features — so that both sides know exactly what a file may contain. IMSC is the widely used family for subtitles and captions.

Being told to deliver TTML is therefore incomplete as a specification. The profile, the frame rate and the permitted styling all have to be stated, or the file will validate as XML and still be rejected on ingest.

Frequently asked questions

Is TTML the same as DFXP?: DFXP was an earlier name for a distribution profile of TTML, and the term still appears in older specifications and tools. Treat them as the same family and confirm the exact profile.
Can TTML be converted to SRT?: Yes, with loss. Positioning, styling and region information have no equivalent in SRT, so what survives is the text and the timings.
Why was my valid TTML file rejected?: Almost always a profile mismatch: the file uses a feature the recipient profile forbids, or omits one it requires.
Does TTML support multiple languages in one file?: The format allows language attributes on content, but most distribution profiles expect one language per file. Follow the profile rather than the format’s capability.

Related terms

Sources

W3C: Timed Text Markup Language 2 (TTML2)