What is TTML and why do streaming networks require it?

Timed Text Markup Language (TTML) is an XML-based subtitle specification developed by the W3C. Major streaming broadcasters including Netflix, Amazon Prime Video, the BBC, and Disney+ require TTML or DFXP XML delivery packages because it supports rich positioning, color styling, and exact SMPTE frame rates.

How does SubPreflight handle SMPTE frame rates (24, 25, 29.97, 30 fps)?

SubPreflight inspects the root XML parameters such as ttp:frameRate or frameRate attributes. When cues use frame notation (for example 00:01:10:15), the parser computes millisecond offsets according to that exact frame cadence, preventing audio drift.

Can I convert standard SRT or WebVTT files into TTML XML?

Yes. Switch the conversion direction toggle to "Subtitles to TTML XML". Drop your SRT or WebVTT file to generate a fully compliant W3C TTML 1.0 XML file ready for video broadcast packaging.

How are nested formatting tags like span and br handled?

The parser converts inline line break tags (such as or ) into standard newline breaks, decodes XML character entities, and extracts dialogue cleanly without broken XML fragments.

Are my broadcast subtitle files uploaded to an external server?

No. SubPreflight executes 100% locally in your web browser. No script files, dialogue text, or metadata are ever transmitted across the internet.

.TTML.DFXP.XML.SRT.VTT

TTML to SRT Converter

Convert broadcast TTML, DFXP, and XML subtitles to SRT or WebVTT, or export SRT files into TTML XML. Free, private, and client-side.

100% In-Browser · Zero Upload

Zero latency · Client-side Web Worker

Conversion Direction

TTML / DFXP XML to Subtitles (SRT / VTT)Subtitles to TTML XML

Drop your TTML, DFXP, XML, or Subtitle (SRT, VTT) file here

Parses Netflix, BBC, and SMPTE-TT XML timecodes with zero upload

ReadyConversion Preview0 items30 fps

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Frequently Asked Questions

What is TTML and why do streaming networks require it?: Timed Text Markup Language (TTML) is an XML-based subtitle specification developed by the W3C. Major streaming broadcasters including Netflix, Amazon Prime Video, the BBC, and Disney+ require TTML or DFXP XML delivery packages because it supports rich positioning, color styling, and exact SMPTE frame rates.
How does SubPreflight handle SMPTE frame rates (24, 25, 29.97, 30 fps)?: SubPreflight inspects the root XML parameters such as ttp:frameRate or frameRate attributes. When cues use frame notation (for example 00:01:10:15), the parser computes millisecond offsets according to that exact frame cadence, preventing audio drift.
Can I convert standard SRT or WebVTT files into TTML XML?: Yes. Switch the conversion direction toggle to "Subtitles to TTML XML". Drop your SRT or WebVTT file to generate a fully compliant W3C TTML 1.0 XML file ready for video broadcast packaging.
How are nested formatting tags like span and br handled?: The parser converts inline line break tags (such as <br/> or <tt:br/>) into standard newline breaks, decodes XML character entities, and extracts dialogue cleanly without broken XML fragments.
Are my broadcast subtitle files uploaded to an external server?: No. SubPreflight executes 100% locally in your web browser. No script files, dialogue text, or metadata are ever transmitted across the internet.