Add your SRT file
Drop one or more .srt 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.
SRT to SMI
Converting a .srt file to .smi 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 SRT 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 SubRip subtitles to SAMI captions
Converting a .srt file to .smi extracts the document's content from its office package into a portable form. A .srt file is a SubRip subtitle document: numbered cues with start and end timestamps and plain caption text. It is the most common caption sidecar for video players, editors, and streaming toolchains that need a simple, widely understood text format.
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. For this route the practical draw is several language tracks in one file, chosen by class and plain text and editable anywhere — balanced against never formally standardised, so real-world files vary in structure, which is worth knowing before you commit a large batch.
Why convert SRT to SMI?
The practical trigger for this conversion is usually a mismatch: with .srt, no standard support for advanced styling, voices, or regions. Switching to .smi buys you several language tracks in one file, chosen by class, which is why it is the better fit for captioning legacy Windows Media and Silverlight content. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
SRT vs SMI at a glance
| Aspect | SubRip subtitles (.srt) | SAMI captions (.smi) |
|---|---|---|
| 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 | cues are blocks of an index, a timecode arrow line (HH:MM:SS,mmm --> HH:MM:SS,mmm), one or more text lines, and a blank separator | the document has an HTML shape: <SAMI> wrapping <HEAD> with a <STYLE> block and <BODY> with the SYNC elements |
| Strongest at | delivering captions alongside MP4 or MKV downloads | captioning legacy Windows Media and Silverlight content |
| Weak spot | no standard support for advanced styling, voices, or regions | never formally standardised, so real-world files vary in structure |
Pick SMI as the output
Select .smi in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if SMI 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 SMI file. Outputs keep the original filename with the .smi extension.
SRT to SMI questions, answered
Will converting SRT to SMI lose quality?
There is no visual quality to lose — srt is text-oriented and smi 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 SRT files here?
Yes — the .srt 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 SMI file work?
Windows Media Player, VLC, PotPlayer, and MPC-HC read .smi, and Subtitle Edit converts it. Browsers do not. Novus Convert parses the SYNC blocks locally with document types and external entities refused and script and style content removed before any text is read, then writes any of the twelve timed-text targets.
Will the SMI file be bigger or smaller than my SRT?
It depends on the content: the document has an HTML shape: <SAMI> wrapping <HEAD> with a <STYLE> block and <BODY> with the SYNC elements. Convert one representative file first and compare before batch-processing a large set.
Can I convert SMI back to SRT?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .srt → .smi → .srt is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.