Convert SRT to SMI Online

Convert SRT to SMI (SAMI) Online

This tool converts a SubRip .srt subtitle file into SMI — Microsoft's SAMI caption format, the HTML-like markup that legacy Windows Media Player builds and many classic Korean media players expect. The conversion runs entirely in your browser: the file is parsed and rewritten on your own device, never uploaded to a server, so it is instant and private. Every cue's text and timing carries over; only the surrounding syntax changes from SRT's numbered timecode blocks to SAMI's <SYNC> markup.

How to Convert SRT to SMI

1. Add Your SRT File: Upload the .srt or paste its contents straight into the input panel — either way the cues appear immediately.
2. Pick SMI as the Output Format: Set the "To format" dropdown to SMI. The converter reads each numbered SRT cue and rewrites it as a SAMI <SYNC> block with millisecond start times.
3. Convert: Click Convert and the SMI markup appears in the output panel.
4. Copy or Download: Copy the result to the clipboard or download it as an .smi file, then drop it next to your video with a matching filename.

SRT vs SMI at a Glance

Property	SRT (SubRip)	SMI (SAMI)
Origin	SubRip ripping tool, early 2000s de-facto standard	Microsoft, late 1990s (Synchronized Accessible Media Interchange)
Syntax	Numbered plain-text cues with 00:00:01,500 --> 00:00:04,000 timecodes	HTML-like markup: <SYNC Start=1500> blocks inside a <SAMI> document
Cue end times	Explicit per cue	Implicit — a cue displays until the next <SYNC> replaces it
Styling	Minimal (basic tags at most)	CSS-like classes in the header, commonly used for multi-language tracks
Plays in	Practically everything: VLC, YouTube, editors, TVs	Legacy Windows Media Player and classic Korean players (PotPlayer, GOM lineage)
Best use today	The universal default	Feeding a player or workflow that specifically asks for .smi

How SRT Timecodes Map to SAMI Sync Points

In the SRT	In the generated SMI	Meaning
00:00:01,500 --> 00:00:04,000	<SYNC Start=1500>	Cue text appears at 1.5 seconds
(the cue's end time, 00:00:04,000)	<SYNC Start=4000> with a clearing block	Text is removed at 4 seconds if a gap follows
00:01:15,250 --> ...	<SYNC Start=75250>	Minutes and hours collapse into one millisecond count

Why SMI Still Comes Up

SAMI is a legacy format, but it refuses to die in two places. First, older Windows software — Windows Media Player above all — loads .smi sidecar files natively where it ignores other formats. Second, SMI became the standard subtitle format of the Korean media ecosystem, so classic players and older subtitle archives from that world are full of .smi files and tools that expect them. If a player, device, or collection specifically wants SMI, this conversion is the bridge; for everything modern, SRT remains the safer format, and the SMI to SRT converter takes you back the other way.

What Changes in the Conversion

• Timing: each SRT start time becomes a SAMI Start value in milliseconds. SAMI has no explicit end times, so a cue runs until the next one begins — where your SRT had a silent gap between cues, an empty sync point is what clears the text.
• Text: the dialogue carries over as-is, including line breaks within a cue. UTF-8 characters — accents, Cyrillic, CJK — survive the rewrite.
• Styling: SRT carries essentially no styling, so the SMI is written with a default class rather than invented colors or fonts. If you need styled SAMI classes, add them afterward in a text editor — the format is plain markup.

Frequently Asked Questions

Is my subtitle file uploaded to a server?

No. This is a client-side converter: the SRT is parsed and rewritten entirely in your browser, and the file never leaves your device. That's also why it's instant — there is no upload or queue, even for a feature-length subtitle track.

Why does my player need SMI instead of SRT?

Because it predates SRT's dominance or comes from the SAMI ecosystem. Legacy Windows Media Player reads .smi sidecars natively, and many classic Korean players and subtitle archives standardized on SAMI. If your player's documentation or an existing subtitle collection says .smi, matching it beats fighting it.

Do the timings stay accurate?

Yes — each cue's start time converts exactly, expressed as milliseconds in the <SYNC Start=...> attribute. The one structural difference is end times: SRT states them explicitly, while SAMI ends a cue when the next sync point arrives, so gaps between cues are handled with clearing sync points rather than an end timestamp.

Will my SRT's italics or formatting carry over?

SRT carries very little formatting to begin with, and the conversion doesn't invent any — the output uses a default SAMI class so every player renders it predictably. SAMI does support CSS-like styling in its header; if you want colored or styled captions, edit the generated .smi in any text editor afterward.

How do I get the SMI file to load with my video?

Save it in the same folder as the video with the same base filename — movie.smi next to movie.avi — and players that support SAMI pick it up automatically. Some players also offer a manual "load subtitle" option if the names differ.

Can I convert SMI back to SRT later?

Yes — SMI to SRT reverses the trip, and because both directions preserve text and timing, a round-trip loses nothing meaningful. Keeping an SRT master is still good practice, since it's the format every modern tool accepts.

What if I need a different subtitle format instead?

The SRT converter hub goes from SRT to the full set — VTT for web video, ASS/SSA for styled subs, and more. If you just want a readable transcript with no timing at all, SRT to TXT strips the timecodes.

Does this work with non-English subtitles?

Yes. The converter treats the text as UTF-8, so accented characters, Cyrillic, and CJK scripts pass through intact — relevant for SMI especially, given its Korean-ecosystem history. If a legacy player shows garbled text, that player may expect a legacy encoding; re-saving the file in the encoding the player's documentation names usually resolves it.