AVI is one of the oldest video container formats still in circulation — a Microsoft format from 1992 that interleaves audio and video data in alternating chunks.
Safe format
Type Video
By Microsoft
MIMEvideo/x-msvideo
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AVI is one of the oldest video container formats still in circulation — a Microsoft format from 1992 that interleaves audio and video data in alternating chunks. The Nokia 3310 of video formats. Indestructible, outdated, and somehow still everywhere. It works, but it lacks modern features like streaming support, variable frame rates, and efficient metadata. AVI files tend to be enormous because the format predates modern compression. You will encounter them in old video archives, security camera footage, and files ripped from DVDs in the mid-2000s. For anything new, MP4 is better in every measurable way.
Technical details
Full Name
Audio Video Interleave
MIME Type
video/x-msvideo
Developer
Microsoft
Magic Bytes
52 49 46 46 ?? ?? ?? ?? 41 56 49 20
Safety
.avi is a known, safe format.
What opens it
VLC
FREEAll
Windows Media Player
FREEWindows
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FAQ
What is the difference between AVI and MP4?
MP4 is the modern standard — smaller files, better compression, streaming support, and universal compatibility. AVI is a legacy format from 1992 with none of those advantages. The only reason to keep a file as AVI is if you are preserving an old archive exactly as-is.
How do I play an AVI file?
VLC (free, all platforms) plays virtually every AVI file regardless of codec. Windows Media Player handles some AVI files but may need additional codecs. If you want to modernise the file, convert it to MP4 with <a href="https://fwip.app/tools/avi-to-mp4/">fwip's AVI to MP4 converter</a>.
Why are AVI files so large?
AVI often uses older, less efficient codecs (like DivX, Xvid, or even uncompressed video). The container itself also lacks modern compression metadata. Converting to MP4 with H.264 can reduce file size by 50–80% with no visible quality loss.
How do I convert AVI to MP4?
Use <a href="https://fwip.app/tools/avi-to-mp4/">fwip's AVI to MP4 converter</a> for quick browser-based conversion. For batch jobs or fine-tuned settings, HandBrake (free) is the go-to tool.