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TTML to SMI Subtitle Converter

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100% local processing in your browser. No upload. No waiting.

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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>
SMI
<SAMI>
<BODY>
<SYNC Start=1000><P Class=ENCC>Hello, world!</P>
<SYNC Start=4000><P Class=ENCC>&nbsp;</P>
<SYNC Start=4500><P Class=ENCC>This is a subtitle file.</P>
<SYNC Start=8000><P Class=ENCC>&nbsp;</P>
<SYNC Start=8500><P Class=ENCC>Converted locally!</P>
<SYNC Start=12000><P Class=ENCC>&nbsp;</P>
</BODY>
</SAMI>

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Supports .ttml, .itt, .xml files up to 50 MB

100% LocalNo UploadSecureInstant

How It Works

1

Upload TTML File

Drag & drop or select your .ttml file

2

Convert Instantly

We process it locally in your browser

3

Download SMI

Get your .smi file immediately

Why Choose AllSubConverter?

Your Privacy Matters

Everything runs in your browser. Your files are never uploaded.

Lightning Fast

Optimized processing engine converts files in seconds.

Free & Local

Each file can be up to 50 MB. Batches can contain up to 200 files or 1 GB total.

Works Everywhere

Works on Windows, Mac, Linux, iOS, Android - any modern browser.

Free Online TTML to SMI Converter

This converter reads <p> cues from a TTML document and writes a SAMI document. Cue starts become millisecond <SYNC Start> values, line breaks become <br> tags, HTML special characters are escaped, and each cue end is marked with a blank <SYNC> entry. The output uses one default ENCC language class.

Input Format

TTML

TTML (Timed Text Markup Language) is an XML subtitle format. This converter looks for <p> elements with begin and end, or begin and dur, timing attributes, and accepts second-based or clock-valued timing. Cues without a begin attribute are skipped.

Output Format

SMI

SMI (SAMI, Synchronized Accessible Media Interchange) is an HTML-like subtitle format using <SYNC> elements with millisecond Start times. This converter emits a single-language document with one default ENCC class; it does not create multiple language tracks.

Features

Reads TTML <p> cues with begin/end or begin/dur timing
Writes millisecond <SYNC Start> values
Converts line breaks to <br> tags
Escapes HTML special characters
Marks cue ends with blank <SYNC> entries
Processes files locally in your browser

Why Convert?

SAMI is useful for legacy playback environments that expect its HTML-like structure.
The output retains explicit start and end timing through paired <SYNC> entries.
HTML escaping keeps cue text safe inside the SAMI document.
A single default language class keeps the generated document predictable.

Format Differences

TTML stores cues in XML <p> elements; SAMI uses <SYNC> and <p> elements.
TTML timing attributes are converted to SAMI millisecond Start values.
TTML line breaks become <br> tags.
TTML source styling is not mapped; the output uses one default ENCC class.

Common Use Cases

Legacy Caption Format

Create a SAMI document for an older workflow that accepts SMI captions.

Timing Conversion

Move TTML begin and end values into paired SAMI <SYNC> entries.

Text Safety

Escape ampersands and angle brackets while retaining cue line breaks.

Related Formats

Frequently Asked Questions

No. It creates one single-language SAMI document with one default ENCC class.

TTML line breaks are written as <br> tags in the SAMI output.

Yes. There is no registration or watermark, and conversion happens in your browser.

Each cue is followed by a blank <SYNC> entry at the cue end time.

Yes. Ampersands, less-than signs, and greater-than signs are escaped for the HTML-like SAMI document.

No. Processing stays in your browser and the subtitle file is not uploaded.

Ready to convert your subtitles?

Drop your TTML file here and convert to SMI instantly.