Two Microsoft formats, two different ages
AVI (Audio Video Interleave) was introduced by Microsoft in 1992, years before WMV. Both come from Windows, but they were built for different things. WMV was designed for streaming and small downloads. AVI is a simple container that became the standard for home video on PCs in the DivX and Xvid era. Because it is so simple, many devices that were built before MP4 became common can read AVI and nothing else.
Who still needs AVI
- DVD and media players with a DivX or USB port that refuse WMV files.
- Older video editing and presentation programs that only import AVI.
- Car entertainment systems, digital photo frames and portable players from the 2000s.
- Lab, school or industrial software that expects AVI input.
If none of these apply, MP4 is usually the better target. It produces smaller files and plays on modern phones and Macs, which AVI often does not. See WMV to MP4.
How the conversion is done
When you convert WMV to AVI here, both formats are handled by the built-in converter engine that runs in the browser, because browsers cannot read or write either one natively. Every frame is decoded from the Windows Media codec and encoded again, and the WMA sound is converted to an audio codec that AVI players understand. This is not instant: plan a few minutes for a long video. Since your files never leave your computer, a slow internet connection does not matter. You can add a whole batch of WMV files, leave the tab open and collect all the AVI files as one ZIP when they are done.
Size and quality
AVI files are often bigger than the WMV they came from, because the codecs used in AVI are older and less efficient. If the result is too big, choose a smaller resolution such as 480p or a lower quality preset, or shrink it later with the AVI Compressor. To go the other way, use AVI to WMV.