TTML File Format (.ttml)
A TTML file is an XML document that marks up timed text with a <body> of styled, positioned regions and a series of <p> elements carrying start and end times, built to move captions between broadcast and streaming systems without losing formatting.
TTML at a glance#
| Full name | Timed Text Markup Language |
|---|---|
| File extension | .ttml |
| Category | Subtitles |
| Developer | World Wide Web Consortium (W3C) |
| First released | 2010 |
| MIME types | application/ttml+xml |
| Other extensions | .dfxp |
| Compression | Uncompressed |
| Specification | TTML2: Timed Text Markup Language 2 |
| FileFlip support | FileFlip writes this format but cannot open one |
What a .ttml file can hold#
These are the things a TTML file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Selectable text | Yes |
|---|---|
| Human readable | Yes |
| Schema or validation | Yes |
Strengths and limitations of TTML#
What TTML does well
- XML structure with a formal schema, so files can be validated for conformance rather than just eyeballed
- Styling and layout regions are defined precisely enough that captions render the same way across compliant players
- Backed by strict delivery profiles (SMPTE-TT, EBU-TT, IMSC) that broadcasters and streaming services standardize on
- Handles multiple languages and both left-to-right and right-to-left text within one file
Where TTML falls short
- Far more verbose than a plain-text format like SRT, since every caption is wrapped in XML markup
- Interoperability depends on both ends supporting the same profile; a file built for one profile can fail validation on a system expecting another
- Not something most people hand-author; it's produced by captioning tools and delivery pipelines rather than typed directly
Use TTML when delivering captions into a broadcast or streaming pipeline that expects it, such as Netflix's or the EBU's ingest specifications.
Convert TTML to SRT or VTT when the destination is a general video player rather than a broadcast or streaming delivery system, since those rarely parse TTML directly.
How to open a .ttml file#
A .ttml file opens in the programs below, grouped by the platform you are on.
| Platform | Programs that open it |
|---|---|
| Windows | Subtitle Edit |
| macOS | Subtitle Edit |
| Web | FileFlip |
TTML questions people ask#
What is a TTML file used for?
A TTML file carries styled, timed captions through broadcast and streaming delivery pipelines, the way Netflix, the EBU and other distributors specify for ingesting subtitles. It's built for interchange between systems, not for opening directly in a typical media player.
What's the difference between TTML and SRT?
TTML is XML with formal styling, regions and a validating schema, while SRT is plain numbered text with no styling at all. TTML is what a broadcast or streaming pipeline expects; SRT is what almost every consumer video player expects.
Is a DFXP file the same as TTML?
Yes. DFXP, Distribution Format Exchange Profile, was TTML's original name before the W3C renamed the standard TTML, and .dfxp files use the same XML structure as .ttml files.
Converting TTML files#
FileFlip cannot open a .ttml file, so there is nothing to convert it into here. It appears on the site as something other formats can be converted to.
Convert another format to TTML
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.