Convert ASS to TTML Online Free
Convert ASS subtitle files to W3C TTML XML format for professional broadcast and streaming platform delivery. ChangeThisFile handles the conversion server-side and auto-deletes your file.
By ChangeThisFile Team · Last updated: March 2026
ChangeThisFile converts ASS to TTML on a secure server. Upload your ASS subtitle file and it is converted to W3C TTML XML with proper namespaces and begin/end attributes. Files are auto-deleted after conversion. Free with no signup required.
Convert ASS to TTML
Drop your ASS file here to convert it instantly
Drag & drop your .ass file here, or click to browse
Convert to TTML instantly
ASS vs TTML: Format Comparison
Key differences between the two formats
| Feature | ASS | TTML |
|---|---|---|
| Structure | Plain text with [Script Info] and [Events] blocks | XML with namespace declarations |
| Styling | Inline style tags with \b, \i, \c syntax | XML tts:* attributes in style elements |
| Positioning | \pos(x,y) coordinates | Named region elements with tts:origin |
| Broadcast compatibility | Consumer players only | Professional broadcast and streaming |
| Karaoke support | Full syllable-level timing | No native karaoke support |
| File size | Compact | Larger due to XML overhead |
| Best for | Anime and styled consumer video | Netflix, Amazon, broadcast delivery |
When to Convert
Common scenarios where this conversion is useful
Submitting to broadcast and streaming platforms
Netflix, Amazon Prime, and Disney+ require TTML-based subtitle formats for professional delivery. Converting ASS to TTML is the first step toward meeting professional subtitle specifications.
Integrating with NLE broadcast workflows
Professional non-linear editors and broadcast subtitle systems like EZTitles and Cavena work with TTML. Converting ASS to TTML allows fansub-quality timing to be imported into professional toolchains.
MPEG-DASH and HLS streaming
Adaptive streaming formats like MPEG-DASH support TTML as a subtitle sidecar. Converting ASS to TTML enables subtitle delivery alongside fragmented video streams.
How to Convert ASS to TTML
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1
Upload your ASS file
Drag and drop your ASS subtitle file onto the converter, or click browse to select it. The file is transferred over an encrypted connection.
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2
Server-side conversion
The server parses each ASS dialogue line, converts timestamps to TTML's HH:MM:SS.mmm format, strips ASS styling tags, and produces a well-formed TTML XML document.
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3
Download the TTML
Save your converted TTML file. The server copy is automatically deleted after processing.
Frequently Asked Questions
TTML (Timed Text Markup Language) is the W3C standard for subtitle interchange. It is used by Netflix, Amazon, Disney+, BBC, and broadcast networks for professional subtitle delivery and accessibility compliance.
Basic timing and text content are preserved. ASS-specific styling (\b, \i, \c, \pos) is stripped during conversion. The resulting TTML uses plain text p elements without tts styling attributes.
Yes. The output conforms to W3C TTML 1.0 with standard tt, head, body, div, and p elements and xmlns namespace declarations.
Karaoke syllable timing (\k, \K) is dropped. TTML does not support karaoke. Only cue-level begin and end attributes are preserved.
Netflix (IMSC-1) and Amazon use strict TTML profiles requiring specific region and styling attributes. The basic TTML output from this converter may need additional editing to meet exact delivery specs.
Yes. Files are transferred over HTTPS and automatically deleted from the server after the TTML is ready for download.
TTML uses HH:MM:SS.mmm format for begin and end attributes on each p element, e.g. begin="00:01:23.456" end="00:01:26.789".
Subtitle files are plain text. The 50 MB server limit is not a concern for ASS files.
Yes. ChangeThisFile supports TTML to ASS conversion for round-tripping between formats.
Yes. The XML output is well-formed and can be validated with any XML parser. For TTML-specific compliance, use the W3C TTML validator.
Related Conversions
Need to convert programmatically?
Use the ChangeThisFile API to convert ASS to TTML in your app. No rate limits, up to 500MB files, simple REST endpoint.
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