How to use the WMV to MP4 converter
- Drop the Windows Media clips (.wmv or .asf) onto the page.
- Choose a quality, or a lower resolution under More settings for lighter files.
- Hit Convert to MP4, then download.
Which Windows Media files work
ffmpeg decodes WMV1, WMV2, WMV3 (Windows Media Video 9) and VC-1 picture, as well as WMA and WMA Pro sound. Everything is encoded fresh as H.264 and AAC, and the MP4 is normally clearly smaller than the WMV at a similar look.
Files locked with Windows Media DRM cannot be decoded, and the queue will show an error for them.
No extra software on a Mac or Chromebook
On a Mac, WMV usually shows up as an email attachment that QuickTime will not play. Safari, Chrome or Firefox can convert it here without installing VLC or old plug-ins, because the decoder comes with the page as WebAssembly. Chromebooks work the same way.
The engine uses a single CPU core, so a half-hour WMV can need several minutes. Leave the tab open until the Download button shows.
Movie Maker exports and old screen captures
Finished videos exported from Windows Movie Maker or Windows Live Movie Maker convert cleanly. Their .wlmp or .mswmm project files are not videos, though; export a WMV from Movie Maker before converting.
Captures made with the old Windows Media Encoder use a screen codec that ffmpeg can also read.
Questions
Why did the file get smaller?
H.264 packs a picture into fewer bits than WMV2 or WMV3 do, so the same look needs less space.
Can I go the other way, MP4 to WMV?
Yes. Open the video converter and pick WMV as the output.
Can I make the MP4 smaller still?
Choose Small file, or pick 720p or 480p under More settings. Lower resolutions are only applied to videos taller than the setting.
Are the videos uploaded?
No. Decoding and encoding both run locally in the tab.