Video converter · runs 100% in your browser
WMV to MKV Converter
Convert WMV video to MKV in your browser. WMV is Windows Media Video container, native on Windows; MKV is open Matroska container, supports many codecs and subtitle tracks. The re-encoding runs through a WebAssembly FFmpeg build — no cloud render farm, no upload bar, no privacy worries.
How to use
- Drop your WMV video onto the page.
- FFmpeg.wasm boots locally on first use — give it a moment, it caches for the rest of your session.
- Re-encoding to MKV happens entirely in your browser; your video never uploads.
- Download the MKV file when conversion finishes — large videos take a few minutes.
FAQ
Why is the first WMV to MKV conversion slow to start?
The first audio or video conversion of your session downloads the FFmpeg.wasm runtime (~25 MB). Subsequent conversions skip that step. After it loads, WMV → MKV re-encoding starts immediately.
Does the converter re-encode or just remux?
It re-encodes both video and audio so that the resulting MKV file is widely compatible. Pure remuxing is a future option but is not yet exposed in the UI.
What codec does the MKV output use?
H.264 video and AAC audio. Quality and bitrate are tuned for a sensible default.
Does video really not upload?
Correct. The conversion runs locally via FFmpeg.wasm. You can verify in DevTools: no outbound traffic carrying your file.