WMV to MP4 Converter
Convert WMV to MP4 so old Windows Media videos, ASF files and Windows Movie Maker exports play on a Mac, an iPhone, Android phones and smart TVs. ProMedia decodes WMV, VC-1 and WMA with its built-in FFmpeg engine and writes H.264 video with AAC audio, all inside your browser. Once the engine has loaded it also works offline, and nothing is uploaded.
- Runs on your device
- FFmpeg
- WebCodecs · GPU
- Works offline
Updated
Drop your videos here
How to convert WMV to MP4
Step 1: Drop your WMV or ASF files on the box above.
Step 2: On first use the FFmpeg engine (about 31 MB) downloads and is cached.
Step 3: Press Convert; Balanced quality suits most clips.
Step 4: Download the MP4 files, or a ZIP of all of them.
Good to know
Settings explained
- Quality
- Only used when a stream has to be re-encoded. Compatible streams are copied with no quality loss.
- Faster: Smaller file, quickest export
- Balanced: Good quality at a sensible size
- Best quality: Largest file, slowest export
- Video codec
- Automatic copies the original video stream when the new format can hold it, so there is no quality loss.
- Automatic: Best codec the format and your device support
- H.264 (AVC): Plays everywhere
- H.265 (HEVC): About 35% smaller, newer devices
- VP9: Web / WebM
- AV1: Smallest files, slowest to encode
- Always re-encode
- Off: compatible streams are copied instantly and losslessly. On: every stream is re-encoded, which can fix playback glitches.
Formats
Batch-friendly: add many files and they are processed one after another — if one fails, the rest still finish.
How it runs
- FFmpeg (when needed)
- Older formats and a few filters use FFmpeg compiled to WebAssembly. It downloads once (about 31 MB) the first time it is needed and is cached for offline use.
- Hardware video engine
- Video is decoded and encoded by your device’s media hardware through WebCodecs — usually several times faster than real time.
WMV vs MP4: quality and file size
Quality depends on bitrate, not on the extension, but WMV’s codecs are older and less efficient than H.264. Re-encoding a WMV to H.264 at a constant-quality setting usually keeps a similar-looking picture in a similar or smaller file, and that file plays far more widely.
| Feature | WMV (Windows Media Video) | MP4 |
|---|---|---|
| Made by | Microsoft | MPEG, published as an ISO standard |
| Video codecs | WMV7, WMV8, WMV9 / VC-1 | H.264, HEVC, AV1 |
| Audio | WMA | AAC |
| Plays on Mac, iPhone and Android | Not without extra apps | Yes |
| Bits for the same picture | More (older codecs) | Fewer with H.264 |
What is a WMV file?
A WMV file is Windows Media Video: Microsoft’s codec family, stored in the ASF (Advanced Systems Format) container with WMA audio. It was the default export of Windows Movie Maker and common on Windows PCs through the 2000s. Macs, iPhones and Android phones ship without a WMV decoder, which is why these files will not play there.
Does converting WMV to MP4 lose quality?
A little, in theory: every frame is decoded and encoded again with x264, because MP4 players do not accept WMV or VC-1 video. In practice the constant-quality setting (CRF 27 at Balanced, 23 at Best quality) keeps the change hard to see on typical WMV footage, which was rarely very sharp to begin with.
Why WMV files won’t play on a Mac
macOS and QuickTime never included Windows Media codecs, and Microsoft stopped offering Windows Media Player for Mac many years ago. Instead of hunting for a player plug-in, convert once: the MP4 opens in QuickTime, Photos, iMovie and every browser.
Tips & troubleshooting
Windows Media Player plays WMV but has no way to save it as MP4; this page covers that step. Only want to watch the file on a Mac or Chromebook? The online video player plays WMV right in the browser.
Need the MP4 under an upload limit as well? Run it through the video compressor afterwards.
Old 320×240 clip looks dull after converting? That is the source, not the conversion; video color correction can lift contrast and colour.
Have AVI or FLV files from the same era? AVI to MP4 and FLV to MP4 work the same way.
WMV to MP4 Converter FAQ
How do I convert WMV to MP4 on Windows 10?
Open this page in Edge or Chrome, drag the WMV files from File Explorer onto the drop zone and press Convert. The MP4s are saved to Downloads. No codec pack or extra software is needed, because the decoder runs inside the browser.
How do I convert WMV to MP4 on Mac?
Open the page in Safari or Chrome and drop the WMV files there. ProMedia decodes Windows Media on the Mac itself with FFmpeg, then saves an H.264 MP4 that QuickTime and iMovie open.
WMV vs MP4: which is smaller?
For the same visual quality, MP4 with H.264 is usually smaller, because H.264 is a newer, more efficient codec than WMV7 to WMV9. A WMV that was saved at a very low bitrate may not shrink further, since the encoder keeps the detail that is there.
Can I convert WMV to MP4 for free?
Yes. There is no sign-up, no watermark and no daily limit, and the file is never uploaded. The only download is the FFmpeg engine itself, once, which the browser then keeps for offline use.
Is your video uploaded anywhere?
No. Your video is processed by your own browser on your own device. There is no server that receives files, so nothing is uploaded, stored or shared. You can even switch to airplane mode once the page has loaded.