TTML to SMI Subtitle Converter
Convert TTML cue timing and text into a single-language SAMI document.
Drag & drop your TTML file here
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Supports .ttml, .itt, .xml files up to 50 MB
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.
TTML to SMI Code Syntax & Structure Inspection
Side-by-side code inspection illustrating header definitions, timestamp syntax, and cue payload formatting
TTML vs SMI Technical Specifications
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.
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.
Format Differences
Conversion Troubleshooting & Gotchas
Practical solutions for player compatibility, character encoding, and timing synchronization
Subtitle timing drifts or appears out of sync on media players
Video files frequently differ in framerate (e.g., 23.976 fps vs 25 fps). If the timing drifts steadily, use our Subtitle Sync tool to adjust the global offset or framerate stretch.
Characters appear as garbled symbols or question marks (Mojibake)
Legacy files saved in Windows-1252, Shift-JIS, or GBK may render incorrectly. Our exporter standardizes output to clean UTF-8. Use our Subtitle Encoding Converter if the source file is corrupted.
Overlapping captions when multiple speakers talk simultaneously
Different formats handle overlapping dialogue differently. If your target player cannot render stacked cues cleanly, open the file in our Subtitle Editor to adjust individual cue timings.
Video editing software (Premiere, DaVinci, Final Cut) rejects the file
Professional NLE software enforces strict syntax rules. Our converter eliminates malformed line breaks and non-standard tags, producing clean, standardized files.
Features
Why Convert?
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
How It Works
- 1
Select or drop a TTML file.
- 2
The parser extracts <p> text and timing attributes.
- 3
Common inline TTML tags are removed and text entities are decoded.
- 4
Each cue is written to an ENCC paragraph with a millisecond start time.
- 5
A blank <SYNC> entry marks the cue end.
More Subtitle Tools
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.
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