Can I add styling to the TTML output?

The converter produces structurally valid TTML with default styling. You can edit the output in a text or XML editor to add tts: styling attributes (color, fontFamily, fontSize, origin, extent, textAlign) to individual elements or define styles in the section.

Is this converter free?

Yes, completely free with no sign-up, no watermarks, and no file size limits. All processing happens in your browser. No subtitle files are ever uploaded to a server.

What file extension should I use?

TTML files can use .ttml or .xml extensions. For Netflix delivery, .itt (Interactive Timed Text) is sometimes used. The converter produces a .ttml file, which can be renamed as needed for your delivery platform.

Can I convert SRT to TTML for Apple TV?

Yes. Apple TV uses a TTML-derived format called ITV. The TTML output from this converter is compatible with Apple TV delivery after verification against Apple's specific ITV profile requirements.

How does TTML differ from IMSC?

IMSC (IMSC1 or IMSC1.1) is a specific profile of TTML used by Netflix and other streaming platforms. TTML is the base format; IMSC constrains it to a specific subset of features. This converter produces standard TTML, which is compatible with IMSC profiles.

Are timestamps frame-accurate after conversion?

SRT timestamps are millisecond-based, and the converter preserves this precision in the TTML output. TTML also supports frame-based time expressions (e.g., 1f, 24fps), but the converter uses time-based expressions matching the SRT source.

Can I batch convert multiple SRT files to TTML?

This page converts one file at a time. For batch processing, use the Workspace feature to load multiple SRT files and convert them sequentially through the pipeline.

Is my subtitle data private?

Absolutely. All conversion happens client-side in your browser. No subtitle data, file contents, or metadata is ever transmitted to a server.

What happens to non-standard SRT tags like or ?

Some SRT files include HTML-like tags (italic, bold). The converter passes these through as XML elements in the TTML output, wrapping text in or similar styling elements where appropriate.

Does the output include language metadata?

The TTML output can include xml:lang attributes for language identification. You can specify the target language when configuring the conversion, and the output will include the appropriate language code in the document structure.

How large are TTML files compared to SRT?

TTML files are typically 2-3x larger than the equivalent SRT due to XML structure, namespace declarations, and element tags. A 50 KB SRT file will produce a roughly 100-150 KB TTML file.

Can I edit TTML files in subtitle editors?

Yes. Professional subtitle editors like Subtitle Edit, OOONA, and EZTitles support TTML editing. You can also edit TTML in any text or XML editor since it is plain XML text.

What if my SRT file has overlapping or negative timestamps?

The converter handles overlapping timestamps by converting each cue independently. Negative timestamps (which are invalid) are sanitized. The output preserves the original timing relationships from the SRT source.

SRT to TTML Converter

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SRT

1
00:00:01,000 --> 00:00:04,000
Hello, world!
 
2
00:00:04,500 --> 00:00:08,000
This is a subtitle file.
 
3
00:00:08,500 --> 00:00:12,000
Converted locally!

TTML

<?xml version="1.0" encoding="UTF-8"?>
<tt xml:lang="en" xmlns="http://www.w3.org/ns/ttml">
  <body>
    <div>
      <p begin="1.000s" end="4.000s">Hello, world!</p>
      <p begin="4.500s" end="8.000s">This is a subtitle file.</p>
      <p begin="8.500s" end="12.000s">Converted locally!</p>
    </div>
  </body>
</tt>

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How It Works

Upload SRT File

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About SRT to TTML

This converter transforms SubRip (SRT) subtitle files into TTML (Timed Text Markup Language) format. TTML is an XML-based subtitle standard developed by the W3C and adopted by Netflix, Apple TV, Amazon Prime Video, and broadcast organizations worldwide. While SRT is a simple plain-text format perfect for consumer use, TTML provides the structured XML, styling capabilities, and metadata required by professional streaming platforms and broadcast delivery workflows.

Input Format

SRT

SRT (SubRip) is a plain-text subtitle format with sequentially numbered cues, HH:MM:SS,mmm timestamps, and simple text lines. It is the universal interchange format that most subtitle editing tools (Aegisub, Subtitle Edit, Jubler) export by default. SRT contains no styling, positioning, or metadata capabilities.

Output Format

TTML

TTML (Timed Text Markup Language) is a W3C XML-based subtitle format used by Netflix (as IMSC/ITT), Apple TV (as ITV), Amazon Prime Video, and broadcast systems (as EBU-TT-D). TTML supports inline styling, text positioning, language metadata, forced narratives, and complex multi-region layouts that professional delivery requires.

Features

Converts SRT comma-separated timestamps to TTML begin/end time expressions automatically

Generates valid TTML XML with proper namespace declarations (tt, ttm, tts, ittp)

Wraps subtitle text in <p> elements within <body> and <div> containers

Converts SRT newlines to <br/> tags for proper line breaks in TTML

Escapes XML special characters (ampersand, angle brackets) for valid output

Produces Netflix-compatible ITT structure when used for streaming delivery

Supports frame-rate-based timing expressions for broadcast workflows

100% client-side processing, no uploads, complete privacy

Why Convert?

Netflix requires TTML-based IMSC (Interactive Media Subtitling and Captions) format for all subtitle delivery, and will reject SRT files submitted through the partner portal.

Apple TV and iTunes use TTML-derived ITV format for subtitles, which requires XML source files rather than plain-text SRT.

EBU-TT broadcast delivery standards (used by European broadcasters) are built on TTML and mandate XML subtitle files for compliance.

Amazon Prime Video requires TTML for subtitle delivery to its platform, rejecting SRT uploads from content partners.

Professional captioning vendors and localization studios work in TTML internally and require XML deliverables rather than SRT.

TTML supports forced narratives (forced subtitles for foreign-language dialogue) as a metadata flag, which SRT cannot represent.

TTML allows per-cue styling (font, color, positioning, alignment) that SRT completely lacks, essential for accessibility-compliant delivery.

Format Differences

SRT uses comma-separated timestamps (00:01:30,500). TTML uses XML attributes like begin="00:01:30.500" end="00:01:35.000" with dot separators.

SRT is a flat plain-text file with numbered entries. TTML is a structured XML document with <tt> root, <head>, <styling>, <body>, <div>, and <p> elements.

SRT has zero styling support. TTML supports inline styling via tts: attributes (fontFamily, fontSize, color, backgroundColor, textAlign, origin).

SRT uses literal newline characters for line breaks within cues. TTML uses <br/> self-closing tags for explicit line breaks.

SRT has no metadata capabilities. TTML supports language declarations (xml:lang), region definitions, role attributes, and forced narrative flags.

SRT files are 1-3 KB per minute. TTML files are 3-6 KB per minute due to XML overhead, namespace declarations, and structure.

Common Use Cases

Netflix Content Delivery

Netflix requires IMSC/TTML format for all subtitle submissions through their partner portal. Convert your SRT subtitles to TTML before delivering to Netflix for series, films, or documentaries.

Apple TV and iTunes Subtitles

Apple TV and iTunes use TTML-derived ITV format for subtitles. Convert SRT to TTML as the first step in Apple TV subtitle delivery preparation.

Broadcast EBU-TT Compliance

European broadcasters using EBU-TT standards require XML-based subtitle files. Convert SRT to TTML as the foundation for EBU-TT broadcast delivery compliance.

Amazon Prime Video Delivery

Amazon Prime Video requires TTML for subtitle delivery from content partners. Convert your SRT subtitles to TTML before uploading to the Amazon Video Direct portal.

Professional Captioning Workflows

Captioning vendors and localization studios work in TTML internally. Deliver TTML rather than SRT for professional captioning, localization, and accessibility compliance projects.

Related Formats

VTT

WebVTT - the modern web standard. Use VTT instead of TTML when delivering to HTML5 web video and browsers.

SRT

SubRip - the input format for this converter. The universal plain-text subtitle format.

ASS

Advanced SubStation Alpha - another styled subtitle format. Use ASS for anime and karaoke, TTML for streaming platform delivery.

Frequently Asked Questions

What is TTML and why do I need it instead of SRT?

TTML (Timed Text Markup Language) is a W3C XML-based subtitle format required by Netflix, Apple TV, Amazon Prime Video, and broadcast organizations. If you are delivering subtitles to a major streaming platform or broadcast partner, they will likely require TTML (or its variants IMSC, ITV, EBU-TT-D) rather than plain-text SRT.

How are SRT timestamps converted to TTML?

SRT uses HH:MM:SS,mmm format with commas (e.g., 00:01:30,500). TTML uses begin and end attributes with dot-separated time expressions (e.g., begin="00:01:30.500" end="00:01:35.000"). The converter handles this conversion automatically for every cue.

How are multi-line SRT cues handled?

SRT cues with multiple lines (separated by newlines) are converted to TTML <p> elements with <br/> tags between lines. This preserves the line break structure while producing valid XML. For example, two lines of dialogue become: <p>Line one<br/>Line two</p>.

Does this converter produce Netflix-compatible TTML?

Yes. The converter produces TTML XML with proper namespace declarations and structure that is compatible with Netflix IMSC/ITT requirements. However, Netflix may have additional specific requirements for frame rates, aspect ratios, and styling that you should verify against their delivery specifications.

What XML namespaces does the output include?

The output TTML includes standard namespaces: xmlns:tt (timed text), xmlns:ttm (metadata), and xmlns:tts (styling). For Netflix/IMSC compatibility, additional namespaces like ittp (profile) may be included. The structure follows the TTML 1.0 specification.

Does the converter escape XML special characters?

Yes. Characters like ampersand (&), less-than (<), greater-than (>), and quotes are automatically escaped to their XML entities (&, <, >, ") in the output. This ensures the TTML file is valid XML and can be parsed by any XML processor.

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Related Resources

What is SRT?What is TTML?