About TTML Validator

Our TTML Validator is a powerful, free online tool that ensures your TTML (Timed Text Markup Language) files meet proper XML structure and W3C standards. TTML is the industry standard for professional broadcasting, streaming services, and accessibility compliance. Our validator checks XML syntax, namespace declarations, timing attributes, and provides detailed feedback to help you create standards-compliant subtitle files.

What is TTML Format?

TTML (Timed Text Markup Language) is a W3C standard for representing timed text media. Based on XML, TTML provides a rich framework for describing the content, timing, layout, and styling of subtitle and caption content. It's widely adopted by broadcasters, streaming platforms, and content distributors for professional subtitle delivery and accessibility compliance.

TTML Format Structure

Basic TTML Structure:

<?xml version="1.0" encoding="UTF-8"?>
<tt xmlns="http://www.w3.org/ns/ttml" xml:lang="en">
  <head>
    <styling>
      <style xml:id="style1" tts:fontSize="16px"/>
    </styling>
  </head>
  <body>
    <div>
      <p begin="00:00:00.000s" end="00:00:03.000s">
        Subtitle text here
      </p>
    </div>
  </body>
</tt>

TTML Validation Features

XML Well-formedness: Validates proper XML syntax and structure
Namespace Validation: Checks required TTML namespace declaration
Root Element: Ensures proper <tt> root element
Document Structure: Validates <head> and <body> organization
Timing Attributes: Checks begin/end timing format and values
Style Validation: Verifies styling elements and CSS properties

TTML Core Elements

<tt>: Root element containing the entire TTML document.

<head>: Document metadata including styles and layout.

<body>: Content container with timing and presentation.

<div>: Logical grouping of subtitle content.

<p>: Paragraph-level subtitle with timing.

<span>: Inline text with optional styling.

TTML Timing Models

Clock Time

• Format: HH:MM:SS.mmms
• Hours: 00-99
• Minutes/Seconds: 00-59
• Milliseconds: 000-999
• Example: 00:01:30.500s

Offset Time

• Seconds: 123.456s
• Milliseconds: 123456ms
• Frames: 123f (with frameRate)
• Ticks: 123t (with tickRate)
• Example: 90.5s

TTML Styling System

CSS Integration: Uses CSS properties with tts: namespace prefix.

Style Elements: Reusable styles defined in <head> section.

Inline Styling: Direct style attributes on content elements.

Inheritance: Cascading style properties from parent elements.

Layout Control: Region-based positioning and sizing.

Typography: Font family, size, weight, decoration, and spacing.

Common TTML Issues

XML Syntax Errors: Malformed XML, unclosed tags, or invalid characters.

Missing Namespace: TTML namespace not declared or incorrect URI.

Invalid Root: Missing or incorrect <tt> root element.

Timing Format: Incorrect time format or missing time units.

Style References: Undefined style IDs or incorrect references.

Character Encoding: Encoding declaration doesn't match actual encoding.

TTML Namespaces

Standard TTML Namespaces:

• Default: http://www.w3.org/ns/ttml (TTML elements)
• tts: http://www.w3.org/ns/ttml#styling (styling attributes)
• ttp: http://www.w3.org/ns/ttml#parameter (parameters)
• ttm: http://www.w3.org/ns/ttml#metadata (metadata)
• xml: http://www.w3.org/XML/1998/namespace (XML attributes)

Why Use TTML Format?

TTML provides the most comprehensive and standardized approach to subtitle and caption delivery. It's required by many broadcasters and streaming platforms for professional content distribution. TTML ensures accessibility compliance, supports advanced styling and positioning, and provides metadata capabilities essential for professional media workflows.

TTML Applications & Support

Broadcasting: BBC, ITV, ARD, France Télévisions, PBS

Streaming: Netflix, Amazon Prime, Hulu, Disney+

Authoring Tools: EBU-TT Live Toolkit, CaptionHub, Subtitle Edit

Players: DASH.js, Shaka Player, ExoPlayer, VLC

Standards: EBU-TT, IMSC, SMPTE-TT, CTA-608/708

TTML Best Practices

Always include XML declaration with UTF-8 encoding
Declare all required namespaces in the root element
Use consistent timing format throughout the document
Define reusable styles in the head section
Validate against TTML schema for standards compliance
Include xml:lang attribute for language identification
Use semantic structure with div and p elements
Test with target players and delivery platforms

TTML Validator

TTML Input

Validation Results