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 SBV
Converting a .smi file to .sbv 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 YouTube SBV subtitles
Converting a .smi file to .sbv 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.
A .sbv file is a SubViewer-style caption document used by YouTube's caption editor: each cue is a single line of start,end timings followed by the caption text on the next lines, separated by a blank line. It carries the same timed dialogue as SubRip but divides the two timestamps with a comma instead of an arrow. For this route the practical draw is accepted directly by YouTube's caption workflow and simpler than SubRip, with no index numbers to renumber after edits — balanced against almost no desktop or browser player plays .sbv directly, so conversion is usually required, which is worth knowing before you commit a large batch.
Why convert SMI to SBV?
The practical trigger for this conversion is usually a mismatch: with .smi, never formally standardised, so real-world files vary in structure. Switching to .sbv buys you accepted directly by YouTube's caption workflow, which is why it is the better fit for downloading and re-uploading captions through YouTube's caption editor. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
SMI vs SBV at a glance
| Aspect | SAMI captions (.smi) | YouTube SBV subtitles (.sbv) |
|---|---|---|
| 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 | each cue is a timing line H:MM:SS.mmm,H:MM:SS.mmm followed by one or more text lines and a blank separator |
| Strongest at | captioning legacy Windows Media and Silverlight content | downloading and re-uploading captions through YouTube's caption editor |
| Weak spot | never formally standardised, so real-world files vary in structure | almost no desktop or browser player plays .sbv directly, so conversion is usually required |
Pick SBV as the output
Select .sbv in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if SBV 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 SBV file. Outputs keep the original filename with the .sbv extension.
SMI to SBV questions, answered
Will converting SMI to SBV lose quality?
There is no visual quality to lose — smi is text-oriented and sbv 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 SBV file work?
YouTube's caption tools import and export .sbv directly, but most desktop and browser players expect SubRip or WebVTT, so .sbv is typically converted to .srt or .vtt for playback. Any text editor can open and edit it.
Will the SBV file be bigger or smaller than my SMI?
It depends on the content: each cue is a timing line H:MM:SS.mmm,H:MM:SS.mmm followed by one or more text lines and a blank separator. 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 SBV back to SMI?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .smi → .sbv → .smi is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.