Add your SMI file
Drop one or more .smi files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
SMI to ITT
Converting a .smi file to .itt extracts the document's content from its office package into a portable form. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop SMI files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting SAMI captions to iTunes Timed Text
Converting a .smi file to .itt extracts the document's content from its office package into a portable form. An .smi file is a SAMI caption document: HTML-like markup in which <SYNC Start=…> elements mark the millisecond at which a caption appears, and the caption runs until the next SYNC. Microsoft designed it as an accessibility format, so a single file can carry several languages selected by CSS class.
An .itt file is an iTunes Timed Text document: a constrained TTML profile that Apple defined for subtitle delivery to the iTunes Store and Apple TV. Its defining trait is timing — cues are addressed in SMPTE timecode (HH:MM:SS:FF) against a frame rate declared in the document header. For this route the practical draw is frame-accurate timing that lines up exactly with an edit timeline and a narrow, validatable profile with far fewer interoperability surprises than full TTML — balanced against frame timecodes are meaningless without the declared frame rate, so a mis-set header shifts every cue, which is worth knowing before you commit a large batch.
Why convert SMI to ITT?
The practical trigger for this conversion is usually a mismatch: with .smi, never formally standardised, so real-world files vary in structure. Switching to .itt buys you frame-accurate timing that lines up exactly with an edit timeline, which is why it is the better fit for delivering subtitles to Apple's ingest specifications. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
SMI vs ITT at a glance
| Aspect | SAMI captions (.smi) | iTunes Timed Text (.itt) |
|---|---|---|
| Format type | Text-based — characters and structure, so there is no visual quality loss | Text-based — characters and structure, so there is no visual quality loss |
| How it stores data | the document has an HTML shape: <SAMI> wrapping <HEAD> with a <STYLE> block and <BODY> with the SYNC elements | timing is frame-accurate: begin and end are HH:MM:SS:FF timecodes resolved against ttp:frameRate, optionally scaled by ttp:frameRateMultiplier for drop-frame rates such as 23.976 |
| Strongest at | captioning legacy Windows Media and Silverlight content | delivering subtitles to Apple's ingest specifications |
| Weak spot | never formally standardised, so real-world files vary in structure | frame timecodes are meaningless without the declared frame rate, so a mis-set header shifts every cue |
| Metadata | style-class and title information describes presentation and language selection, not the cues; conversion keeps timing and text | the frame-rate parameters are read because timing depends on them; styling attributes are dropped, since millisecond caption targets have nowhere to record them |
Pick ITT as the output
Select .itt in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if ITT is selectable, the route is real and validated.
Convert on your device
Press Convert. The package is unzipped in memory and its XML content parsed locally; nothing is uploaded.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid ITT file. Outputs keep the original filename with the .itt extension.
SMI to ITT questions, answered
Will converting SMI to ITT lose quality?
There is no visual quality to lose — smi is text-oriented and itt is text-oriented, so the question is structural fidelity. Text, ordering, and basic structure are preserved; complex layout, embedded objects, and styling beyond the target's model are simplified.
Is it private to convert SMI files here?
Yes — the .smi file is processed inside your browser tab and never uploaded. The package is unzipped in memory and its XML content parsed locally; nothing is uploaded. Close the tab and the file is gone from memory.
Where will the ITT file work?
Final Cut Pro, Compressor, and Apple's delivery pipelines read and write .itt, and Subtitle Edit imports it. Browsers and consumer players do not. Novus Convert resolves the SMPTE timecodes against the document's own ttp:frameRate and ttp:frameRateMultiplier — falling back to 30 fps only when neither is declared — and exports to any of the twelve timed-text targets.
Will the ITT file be bigger or smaller than my SMI?
It depends on the content: timing is frame-accurate: begin and end are HH:MM:SS:FF timecodes resolved against ttp:frameRate, optionally scaled by ttp:frameRateMultiplier for drop-frame rates such as 23.976. Convert one representative file first and compare before batch-processing a large set.
What happens to the metadata in my SMI file?
In .smi, style-class and title information describes presentation and language selection, not the cues; conversion keeps timing and text. Re-encoding through the browser pipeline does not carry embedded metadata into the output, which doubles as a privacy scrub — check the exported file if you specifically need tags preserved.
Can I convert ITT back to SMI?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .smi → .itt → .smi is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.