How to Convert SRT to TTML
Learn how to convert SRT to TTML for professional streaming and broadcast delivery workflows.
SRT is the subtitle format you find almost everywhere, but professional streaming and broadcast workflows often use TTML-family profiles for caption delivery. If your destination specifies TTML or IMSC, converting SRT to TTML is usually the first step. This guide explains how TTML preserves structure during conversion and how to convert SRT to TTML in seconds.
Why Streaming Platforms Use TTML
TTML (Timed Text Markup Language) is an XML-based subtitle format standardized by the W3C and SMPTE. Unlike SRT, which is plain text with no styling, TTML carries structured metadata: timing, regions, fonts, colors, positioning, and language. That structure is what lets a single subtitle file render consistently across a smart TV, a phone, and a set-top box.
Netflix, Apple, and broadcast suppliers commonly use TTML-family profiles because these formats can carry placement, styling, language, and workflow metadata beyond plain text. IMSC is a widely used constrained TTML profile for internet-media subtitles; the recipient's delivery specification defines the exact profile and metadata required.
The short version: SRT is great for playback, but TTML is the language of professional subtitle delivery.
What Changes When You Convert SRT to TTML
Converting between these formats is not a simple text swap. The converter does three things for you:
1. Timestamps are rewritten. SRT uses HH:MM:SS,mmm with a comma before the milliseconds. TTML expresses timing as begin and end attributes, either in seconds (1.500s) or clock format (00:00:01.500). Both hold millisecond precision, so no timing detail is lost.
2. The file is wrapped in XML. A TTML file is a valid XML document. Each subtitle becomes a <p> element inside a <body>, with a <head> section for styling and metadata. The sequential numbers SRT uses disappear because TTML identifies cues by their attributes, not by a counter.
3. Plain text gains structure. Line breaks become <br/> tags, and the text is placed inside named elements so a player can apply styling and positioning. Because SRT has no styling to begin with, the converted TTML starts unstyled, which you can then enrich in a subtitle editor.
How to Convert SRT to TTML
The fastest way is to use our free SRT to TTML converter. Paste or upload your SRT file, and the tool produces a valid TTML document with the timing, text, and line breaks preserved. Because both formats support millisecond precision, the converted timing is exact.
If your downstream workflow requires an IMSC or EBU-TT profile, the converted TTML is a clean starting point. You can then open it in a subtitle editor to add regions, styling, and language metadata before delivery.
Frequently Asked Questions
Does converting SRT to TTML lose timing accuracy?
No. Both formats support millisecond precision, so the converted TTML holds the exact start and end times of every cue. No rounding is needed.
Is TTML the same as IMSC?
IMSC is a constrained profile of TTML. Every IMSC file is valid TTML, but not every TTML file meets IMSC's stricter rules. Converting SRT to TTML gives you the base structure. Check your recipient's IMSC profile and delivery specification, because additional metadata or styling constraints may apply.
Can I convert TTML back to SRT?
Yes. Use the TTML to SRT converter to extract plain text and timing from a TTML file. Styling and positioning that SRT cannot represent are dropped, but the text and timing remain accurate.