.SMI File Extension

A .SMI file is a Self-Mounting Disk Image, created by Apple.

Open with Apple Disk Utility (Included with OS). Available for Mac.

What is a .SMI file?

The .SMI file extension refers to two different types of files, each used for distinct purposes. 1. **Self-Mounting Disk Image**: This type of .SMI file is primarily associated with older Macintosh systems, specifically Mac OS Classic (Mac OS 9 or earlier). It is a disk image file that was created using software like Aladdin ShrinkWrap or Apple Disk Copy. When you open this type of .SMI file on a compatible Mac system, it automatically mounts as if it were a physical disk, appearing on the desktop. This allows you to access the contents as though you were accessing a real disk drive. To open these files, you can use programs such as Apple Disk Utility (included with the Mac OS), Apple Disk Copy, or Aladdin ShrinkWrap.

2. **SAMI (Synchronized Accessible Media Interchange) Subtitles**: This type of .SMI file is used for storing subtitles for video playback and is developed by Microsoft. It is an extension of HTML and includes specific tags like at the beginning of the file. The subtitles within the file are formatted with tags that define the start time of each subtitle line in milliseconds, the text alignment, font, color, and margins. For example, a subtitle line that appears 3400 milliseconds into a video would be tagged with . These files can be viewed and edited in text editors like GitHub Atom. If you need to convert these .SMI subtitle files into the more commonly used .SRT format, you can use online tools such as or

In summary, the .SMI extension can refer to either a self-mounting disk image for older Mac systems or a subtitle file format used in videos. The appropriate software or tool to open or convert these files depends on the specific type of .SMI file you are dealing with.


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