# Convert WMV to MP4

> Convert WMV to MP4 online free: old Windows Movie Maker videos are re-encoded to H.264 MP4 that plays on every phone and TV. Many at once, no upload.

URL: https://nibbo.org/en/wmv-to-mp4/

## WMV

WMV (Windows Media Video) came with Windows Movie Maker and old Windows phones and cameras. The picture is WMV or VC-1, the sound WMA.

Macs, iPhones, Android and browsers don’t play Windows Media, so every frame has to be re-encoded to H.264.

## WMV to MP4: remux or re-encode

WMV can’t become MP4 without re-encoding: its picture codec isn’t one MP4 players read, so every frame is decoded and encoded again as H.264, with AAC sound.

WMV files are often large for what they show; at the Balanced preset a 1080p minute comes out around 30 MB. Files up to 3 GB are converted, and the FFmpeg path keeps the result in memory, so very long videos need a desktop browser.

## How it works

1. Drop one or more WMV files: MP4 is already selected. Quality, maximum resolution and sound can be changed before you start.
2. Streams that fit MP4 are copied; anything else is re-encoded with WebCodecs, or FFmpeg compiled to WebAssembly when the browser can’t.
3. Download each file, or all of them as one ZIP.

## Questions

### Are my videos uploaded?

No. Reading, remuxing and encoding all run in this browser tab. Open DevTools and watch the Network tab while a file converts: no request carries it.

### Why is one file done in seconds and another takes minutes?

A remux only copies the streams, so it runs at disk speed. A re-encode decodes and encodes every frame; FFmpeg in WebAssembly, used when the browser can’t, is slower still.

### How large can a video be?

Up to 3 GB per file for free, and as many files as you like. Remuxes and WebCodecs re-encodes stream from the disk; the FFmpeg path holds the result in memory.

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