How to open a subtitle file online
Three steps, a few seconds, no software.
Open your .SMI file
Drop it on the box, choose it from your device, or paste its text straight in.
View every line
See the start, end, duration and reading speed of each line, with any problems flagged.
Preview, fix, convert
Play the lines over your video, shift the timing, then download in the format you need.
What is a .SMI file?
Timed text that appears on top of a video.
A SMI file is usually a SAMI caption file, Microsoft's HTML-like subtitle format for video, introduced in 1998. To watch it with a video, give the .smi the same base name as the video and open both in VLC or PotPlayer; the subtitle loads automatically. To convert to the more universal .srt, open the .smi in Subtitle Edit and save as SubRip.
Programs that open .SMI files
| Full name | SAMI Captioning File |
|---|---|
| Developer | Microsoft |
| First released | 1998 (Microsoft SAMI 1.0, alongside Windows Media) |
| Category | Text & Code |
| MIME type | application/smil |
Related viewers
Every viewer is free to use.
Frequently asked questions
Is my .SMI file uploaded?
No. The file is read by your browser. If you preview with a video, the video is also played locally.
My .SMI file is out of sync. Can I fix it?
Yes. If they're early or late by a fixed amount, enter the difference in milliseconds and click Shift. If they drift more and more over time, the frame rate is wrong: use Change FPS (for example 25 → 23.976).
Why are some characters broken (é, ł)?
Older subtitles are often saved in a regional encoding like Windows-1250. We detect it automatically and every download is saved as UTF-8, which works everywhere.
What do the warnings mean?
Overlap: two lines on screen at once. Too fast: more than 20 characters per second. Too short: under 0.83 s. Long line: over 42 characters. 3+ lines: too much text at once.
Can I convert ASS to SRT?
Yes. Italic, bold and underline are kept; positioning and karaoke effects are dropped because SRT can't store them.
Was this tool helpful?
Your rating helps us decide which tools to improve next.