AVI vs WMV: Comparing Two Legacy Video Formats
AVI and WMV both predate the current video landscape by a couple of decades, and both carry real limitations that modern formats like MP4 were built specifically to address. Understanding what those limitations actually are explains why you'll still run into old AVI and WMV files today, and why converting them is usually worth doing rather than leaving them as-is.
AVI: a flexible but dated container
AVI (Audio Video Interleave), developed by Microsoft in 1992, is a container format — meaning it can technically hold video encoded with a range of different codecs inside it. In practice, that flexibility became a real liability: not every piece of software supports every codec that might be packed inside an AVI file, so a given AVI's actual playability depends heavily on exactly which codec was used to encode it, which isn't always obvious from the file itself. AVI files are also frequently much larger than modern equivalents for the same visual quality, since older, less efficient codecs are commonly used with it.
WMV: Microsoft's more consistent proprietary answer
WMV (Windows Media Video), also from Microsoft, provides better compression than typical AVI setups and doesn't have the same codec-lottery problem, since WMV specifically implies Microsoft's own compression technology. Its real limitation is being far more strongly tied to the Windows and Microsoft software ecosystem — playback and editing support on non-Windows platforms has historically been noticeably weaker than for more universal formats.
Why you still encounter these formats today
Old home videos, archived work files, and content created or exported by older software frequently still exist as AVI or WMV, simply because those were the standard formats at the time they were made. There's nothing broken about these files — they play fine in software that supports their specific codec — but they represent an older, generally less efficient and less broadly compatible generation of video technology compared to what's standard today.
Why converting to MP4 is usually the right move
MP4 with modern video codecs (like H.264) generally achieves noticeably better compression than either AVI or WMV typically manage, meaning a smaller file at the same visual quality, and MP4 enjoys close to universal playback support across virtually every device, platform, and piece of software in current use — a level of compatibility neither AVI nor WMV can really match today. For an old AVI or WMV file you want to keep using, sharing, or editing going forward, converting to MP4 is usually a straightforward upgrade with no real downside.
A practical way to decide
If you're holding onto old AVI or WMV files purely for archival purposes and never open them, there's no urgent need to convert. The moment you want to actually share, edit, or reliably play one of these files on a modern device, converting to MP4 removes both the codec-compatibility uncertainty AVI carries and the platform-tied limitations of WMV, typically shrinking the file in the process.
AVI to MP4 and the video converter handle bringing old AVI and WMV files into MP4 directly in your browser, giving them modern compatibility and typically a smaller file size in one step.