TTML
Timed Text Markup Language
An XML-based subtitle format used by streaming services and broadcast workflows. Powerful styling and positioning, but verbose.
In depth
TTML (Timed Text Markup Language) is a W3C XML standard for timed text. Each cue is a <p> element with begin and end attributes inside a <body><div> structure. TTML supports inline styling, positioning, regions, and timing expressions far beyond SRT or VTT. The IMSC profile (TTML 1.1 / IMSC 1.2) is the format Netflix, Hulu, Disney+, and most modern streamers ingest internally; .dfxp and .xml files are usually TTML.
When to use it
Use TTML when delivering subtitles to a streaming platform, OTT service, or broadcast workflow that requires it. Don't pick it for personal projects — SRT or VTT covers the same job in 1/10 the file size.
Example
<tt xmlns="http://www.w3.org/ns/ttml">
<body>
<div>
<p begin="00:00:01.000" end="00:00:03.500">Hello world.</p>
</div>
</body>
</tt>Frequently asked
What's the difference between TTML, IMSC, and DFXP?+
TTML is the W3C standard. IMSC is a constrained profile of TTML built for the broadcast / streaming use case. DFXP (Distribution Format Exchange Profile) is an older Netflix-era profile of TTML; .dfxp files are TTML XML.
Can a video editor open TTML directly?+
DaVinci Resolve, Premiere Pro, and Final Cut Pro all import TTML/IMSC. CapCut and most consumer tools don't — convert to SRT first.
Does TTML support karaoke timing?+
Yes — TTML defines <span> with timing attributes, which is how IMSC encodes word-level highlights. SRT and VTT can't do this natively at the file-format level.
An older subtitle profile of TTML used by Netflix and Adobe Flash. Internally just TTML XML with a .dfxp extension.
The W3C web standard for subtitles. Used by HTML5 <track> elements. Like SRT but with dot-separated milliseconds and styling support.
The most common subtitle file format. Plain text with numbered cues and HH:MM:SS,mmm timestamps.