Convert TTML to ASS Online Free
Convert W3C TTML broadcast subtitle files to ASS format for use in desktop video players and subtitle editing software like Aegisub. ChangeThisFile processes server-side with auto-deletion.
By ChangeThisFile Team · Last updated: March 2026
ChangeThisFile converts TTML to ASS on a secure server. Upload your TTML broadcast subtitle file and it is converted to ASS format for desktop video players and subtitle editors. Files are auto-deleted after conversion. Free with no signup required.
Convert TTML to ASS
Drop your TTML file here to convert it instantly
Drag & drop your .ttml file here, or click to browse
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TTML vs ASS: Format Comparison
Key differences between the two formats
| Feature | TTML | ASS |
|---|---|---|
| Structure | XML with W3C namespace declarations | Plain text with style blocks |
| Primary use | Broadcast and streaming subtitle delivery | Desktop players and anime fansubs |
| Styling | XML-based tts:* attributes | Inline \b, \i, \c override tags |
| Positioning | Region elements with tts:origin | \pos(x,y) coordinate tags |
| Editability | XML editor required | Any plain text editor |
| Player support | Professional broadcast tools | VLC, MPC, mpv, Aegisub |
| Best for | Professional delivery | Desktop video playback and editing |
When to Convert
Common scenarios where this conversion is useful
Editing broadcast TTML subtitles in Aegisub
TTML files from broadcast deliverables can be converted to ASS for editing in Aegisub — the most popular open-source subtitle editor — for timing adjustments and styling refinements.
Playing broadcast subtitles in desktop video players
VLC, mpv, and MPC-HC support ASS natively but not TTML. Converting TTML to ASS lets you load broadcast subtitle files directly in desktop players without additional processing.
Archiving streaming platform subtitles in a universal format
TTML files from streaming platforms can be converted to ASS for local archiving alongside downloaded video files, ensuring compatibility with all mainstream media players.
How to Convert TTML to ASS
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1
Upload your TTML file
Drag and drop your TTML subtitle file onto the converter, or click browse to select it. The file is uploaded over an encrypted connection.
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2
Server-side conversion
The server parses the TTML XML, extracts cue timing and text from each p element, converts timestamps to ASS H:MM:SS.cc format, and writes an ASS file with standard Script Info and Events sections.
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3
Download the ASS
Save your converted ASS file. The server copy is automatically deleted after processing.
Frequently Asked Questions
TTML (Timed Text Markup Language) is the W3C standard for subtitle interchange used by Netflix, Amazon, Disney+, and broadcast networks. It is XML-based with rich styling and positioning support.
Basic timing and text are preserved. TTML tts:fontStyle, tts:color, and tts:textAlign attributes are stripped. Adding equivalent ASS styling requires manual work in Aegisub after conversion.
Yes. Aegisub opens ASS natively and provides a full graphical editor for timing, styling, and positioning. It is the standard tool for working with ASS subtitle files.
VLC, MPC-HC, MPC-BE, mpv, and PotPlayer all support ASS natively. Windows Media Player requires a codec pack like LAV Filters to play ASS subtitles.
Yes. Files are transferred over HTTPS and automatically deleted from the server after the ASS is ready for download.
ASS uses H:MM:SS.cc (centiseconds). TTML's HH:MM:SS.mmm millisecond timestamps are converted to centiseconds, rounding to the nearest 10ms.
TTML files are XML and slightly larger than plain-text formats, but still very compact. The 50 MB server limit is not a concern for subtitle files.
Yes. ChangeThisFile supports ASS to TTML conversion for round-tripping between formats.
Region references in TTML p elements are noted but simplified to a single default ASS style. To restore precise positioning, edit the \pos() coordinates in Aegisub after conversion.
The converter parses standard TTML XML and extracts p element timing and text. Most TTML 2.0 content in p elements converts correctly. TTML 2.0-specific animation and ruby elements are dropped.
Related Conversions
Need to convert programmatically?
Use the ChangeThisFile API to convert TTML to ASS in your app. No rate limits, up to 500MB files, simple REST endpoint.
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