MKV to WebM

Both are Matroska containers underneath, but WebM restricts what is allowed inside, so the video and audio are re-encoded to VP9 and Opus rather than copied.

Runs in your browser // nothing is uploaded

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What survives the conversion

Derived from what each format is able to store, not from what the conversion promises.

Kept

Audio track
Metadata
Alpha channel, which MKV could not store

Lost

Chapters
Multiple tracks
Subtitle tracks

Settings used

VP9 at CRF 32, first audio track to Opus. Subtitle tracks are dropped.

When not to convert

Not if you want to keep the subtitle or alternate audio tracks.

About these formats

Video

What is a WebM file?

WebM is a royalty-free video container introduced by Google in 2010, normally carrying VP8, VP9 or AV1 video with Vorbis or Opus audio. At the same visual quality it is usually smaller than an H.264 MP4, and it supports true alpha transparency, which MP4 in practice does not.

Read the format guide

Common questions

Does converting MKV to WebM lose anything?

Yes. Chapters, Multiple tracks, Subtitle tracks cannot be carried into WebM and are dropped. Both are Matroska containers underneath, but WebM restricts what is allowed inside, so the video and audio are re-encoded to VP9 and Opus rather than copied.

Are my files uploaded when I convert MKV to WebM?

No. The conversion runs in your browser tab, so the file is never transmitted and the page works offline once loaded.

What settings does Filoven use for MKV to WebM?

VP9 at CRF 32, first audio track to Opus. Subtitle tracks are dropped.

When should I not convert MKV to WebM?

Not if you want to keep the subtitle or alternate audio tracks.