AVI
Thirty years old, still on every external drive, and opened by almost nothing.
AVI is a container Microsoft published in 1992. Neither iOS nor current macOS opens one — Apple removed the last of its support years ago — and what is usually inside, DivX or XviD video with MP3 audio, is just as obsolete. The files still work perfectly; the systems around them moved on.
30 July 2026
Opened without help by
Older Macs could open some AVI files through QuickTime 7 and Perian, both long gone. On anything current the file opens as a document with no preview, which is what a system saying "I have never heard of this" looks like.
The facts
| Full name | Audio Video Interleave |
|---|---|
| Kind | Container |
| Extensions | .avi, .divx |
| Published | 1992, Microsoft, built on the RIFF structure |
| Video usually inside | DivX and XviD (both MPEG-4 Part 2), sometimes MJPEG, occasionally H.264 |
| Audio usually inside | MP3, AC-3, or uncompressed PCM |
| Subtitles inside | None — AVI has no subtitle track, which is why .srt files sit next to them |
| Multiple audio tracks | Possible in theory, unreliable in practice |
| File size limit | Original AVI stops at 2 GB; the OpenDML extension raised it, with mixed support |
A container from before streaming existed
AVI was designed for playback from a hard disk on a desktop computer in the early nineties, and it shows. It has no concept of streaming, no proper way to describe a subtitle track, no place to put chapters, and a variable-bitrate audio problem that produced a decade of files where the sound drifts out of sync as the film goes on.
None of that mattered at the time and all of it matters now. Every container that came afterwards — MP4, Matroska, WebM — exists partly because of what AVI could not do.
What it did have was ubiquity. For roughly fifteen years, a video file meant an AVI file, which is why they are still the bulk of what turns up on old external drives, in long-forgotten download folders, and on the DVDs people burned before there were streaming services.
Why Apple stopped
Apple never supported AVI enthusiastically — QuickTime could open some of them, given the right component installed. The component ecosystem died with QuickTime 7, and modern macOS ships no AVI demuxer at all. iOS never had one.
The second half of the problem is the codec. Even a system willing to read the container would find DivX or XviD inside, and Apple ships no decoder for MPEG-4 Part 2 either. So an AVI fails twice over, which is why nothing short of a full software decoding stack opens one.
That is also why converting an AVI is usually slow. Unlike an MKV, where the streams inside are typically already MP4-compatible and can simply be re-labelled, an AVI's video genuinely has to be decoded and re-encoded. Expect a real wait, and a small quality loss.
What to do with a folder of them
- Play them as they are
A player with its own decoders opens AVI, XviD and DivX without touching the files. For an archive you dip into occasionally, this is the whole answer: no conversion, no second copy, no waiting.
- Convert the few you actually watch
If a handful of these are films you return to, re-encoding them to H.264 in an MP4 makes them play everywhere and usually makes them smaller. Do it for the handful, not the folder.
- Keep the subtitle files with them
An AVI cannot hold subtitles, so its subtitles are a separate .srt sitting alongside, matched by filename. Move the video without the .srt and the subtitles are gone — this is the single most common way people lose them.
The two classic AVI faults
A file written with variable-bitrate MP3 audio, which AVI cannot describe properly. It starts aligned and is a second out by the end. Re-encoding fixes it; nothing at playback time really can.
The original specification could not address past 2 GB. A recording that ran long was silently truncated there, and the missing half was never written.
Questions about this format
Nearby formats
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